Science.gov

Sample records for orbital population analysis

  1. NASA Orbital Debris Baseline Populations

    NASA Technical Reports Server (NTRS)

    Krisko, Paula H.; Vavrin, A. B.

    2013-01-01

    The NASA Orbital Debris Program Office has created high fidelity populations of the debris environment. The populations include objects of 1 cm and larger in Low Earth Orbit through Geosynchronous Transfer Orbit. They were designed for the purpose of assisting debris researchers and sensor developers in planning and testing. This environment is derived directly from the newest ORDEM model populations which include a background derived from LEGEND, as well as specific events such as the Chinese ASAT test, the Iridium 33/Cosmos 2251 accidental collision, the RORSAT sodium-potassium droplet releases, and other miscellaneous events. It is the most realistic ODPO debris population to date. In this paper we present the populations in chart form. We describe derivations of the background population and the specific populations added on. We validate our 1 cm and larger Low Earth Orbit population against SSN, Haystack, and HAX radar measurements.

  2. Orbit analysis

    SciTech Connect

    Michelotti, L.

    1995-01-01

    The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators.

  3. Crystal orbital Hamilton population (COHP) analysis as projected from plane-wave basis sets.

    PubMed

    Deringer, Volker L; Tchougréeff, Andrei L; Dronskowski, Richard

    2011-06-01

    Simple, yet predictive bonding models are essential achievements of chemistry. In the solid state, in particular, they often appear in the form of visual bonding indicators. Because the latter require the crystal orbitals to be constructed from local basis sets, the application of the most popular density-functional theory codes (namely, those based on plane waves and pseudopotentials) appears as being ill-fitted to retrieve the chemical bonding information. In this paper, we describe a way to re-extract Hamilton-weighted populations from plane-wave electronic-structure calculations to develop a tool analogous to the familiar crystal orbital Hamilton population (COHP) method. We derive the new technique, dubbed "projected COHP" (pCOHP), and demonstrate its viability using examples of covalent, ionic, and metallic crystals (diamond, GaAs, CsCl, and Na). For the first time, this chemical bonding information is directly extracted from the results of plane-wave calculations. PMID:21548594

  4. Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis

    NASA Technical Reports Server (NTRS)

    Slojkowski, Steven E.

    2014-01-01

    Results from operational OD produced by the NASA Goddard Flight Dynamics Facility for the LRO nominal and extended mission are presented. During the LRO nominal mission, when LRO flew in a low circular orbit, orbit determination requirements were met nearly 100% of the time. When the extended mission began, LRO returned to a more elliptical frozen orbit where gravity and other modeling errors caused numerous violations of mission accuracy requirements. Prediction accuracy is particularly challenged during periods when LRO is in full-Sun. A series of improvements to LRO orbit determination are presented, including implementation of new lunar gravity models, improved spacecraft solar radiation pressure modeling using a dynamic multi-plate area model, a shorter orbit determination arc length, and a constrained plane method for estimation. The analysis presented in this paper shows that updated lunar gravity models improved accuracy in the frozen orbit, and a multiplate dynamic area model improves prediction accuracy during full-Sun orbit periods. Implementation of a 36-hour tracking data arc and plane constraints during edge-on orbit geometry also provide benefits. A comparison of the operational solutions to precision orbit determination solutions shows agreement on a 100- to 250-meter level in definitive accuracy.

  5. Orbiter Autoland reliability analysis

    NASA Technical Reports Server (NTRS)

    Welch, D. Phillip

    1993-01-01

    The Space Shuttle Orbiter is the only space reentry vehicle in which the crew is seated upright. This position presents some physiological effects requiring countermeasures to prevent a crewmember from becoming incapacitated. This also introduces a potential need for automated vehicle landing capability. Autoland is a primary procedure that was identified as a requirement for landing following and extended duration orbiter mission. This report documents the results of the reliability analysis performed on the hardware required for an automated landing. A reliability block diagram was used to evaluate system reliability. The analysis considers the manual and automated landing modes currently available on the Orbiter. (Autoland is presently a backup system only.) Results of this study indicate a +/- 36 percent probability of successfully extending a nominal mission to 30 days. Enough variations were evaluated to verify that the reliability could be altered with missions planning and procedures. If the crew is modeled as being fully capable after 30 days, the probability of a successful manual landing is comparable to that of Autoland because much of the hardware is used for both manual and automated landing modes. The analysis indicates that the reliability for the manual mode is limited by the hardware and depends greatly on crew capability. Crew capability for a successful landing after 30 days has not been determined yet.

  6. Exploratory orbit analysis

    SciTech Connect

    Michelotti, L.

    1989-03-01

    Unlike the other documents in these proceedings, this paper is neither a scientific nor a technical report. It is, rather, a short personal essay which attempts to describe an Exploratory Orbit Analysis (EOA) environment. Analyzing the behavior of a four or six dimensional nonlinear dynamical system is at least as difficult as analyzing events in high-energy collisions; the consequences of doing it badly, or slowly, would be at least as devastating; and yet the level of effort and expenditure invested in the latter, the very attention paid to it by physicists at large, must be two orders of magnitude greater than that given to the former. It is difficult to choose the model which best explains the behavior of a physical device if one does not first understand the behavior of the available models. The time is ripe for the development of a functioning EOA environment, which I will try to describe in this paper to help us achieve this goal.

  7. Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis

    NASA Technical Reports Server (NTRS)

    Slojkowski, Steven E.

    2014-01-01

    LRO definitive and predictive accuracy requirements were easily met in the nominal mission orbit, using the LP150Q lunar gravity model. center dot Accuracy of the LP150Q model is poorer in the extended mission elliptical orbit. center dot Later lunar gravity models, in particular GSFC-GRAIL-270, improve OD accuracy in the extended mission. center dot Implementation of a constrained plane when the orbit is within 45 degrees of the Earth-Moon line improves cross-track accuracy. center dot Prediction accuracy is still challenged during full-Sun periods due to coarse spacecraft area modeling - Implementation of a multi-plate area model with definitive attitude input can eliminate prediction violations. - The FDF is evaluating using analytic and predicted attitude modeling to improve full-Sun prediction accuracy. center dot Comparison of FDF ephemeris file to high-precision ephemeris files provides gross confirmation that overlap compares properly assess orbit accuracy.

  8. Value analysis for orbital debris removal

    NASA Astrophysics Data System (ADS)

    Vance, Leonard; Mense, Allan

    2013-08-01

    This paper presents methods for deriving first order monetary benefits from removing individual debris objects in high value sun-synchronous orbits. These analyses are intended to serve as an economic metric by which competing debris removal methods can be evaluated. Orbital debris flux level estimates from NASA’s updated ORDEM2000 model are used to establish small debris population estimates. When combined with the replacement cost of satellites in sun-synchronous orbit, the present value of removing individual small (0.5 cm-2.0 cm) objects from orbit is derived. Large object removal value is more complicated due to the necessity of incorporating effects of impact fragmentation observed with any object about 10 cm or larger. Breakup models published by NASA (Johnson, N.L., Krisko, P.H., Liou, J.C., Anz-Meador, P.D. NASA’s new breakup model of evolve 4.0. Adv. Space Res. 28 (9), 1377-1384, 2001.) provide a basis for establishing fragmentation statistics. Assuming the current population of operational sun-synchronous satellites, removal value is then derived via present value analysis.

  9. Using GEO Optical Observations to Infer Orbit Populations

    NASA Technical Reports Server (NTRS)

    Matney, Mark; Africano, John

    2002-01-01

    NASA's Orbital Debris measurements program has a goal to characterize the small debris environment in the geosynchronous Earth-orbit (GEO) region using optical telescopes ("small" refers to objects too small to catalog and track with current systems). Traditionally, observations of GEO and near-GEO objects involve following the object with the telescope long enough to obtain an orbit. When observing very dim objects with small field-of-view telescopes, though, the observations are generally too short to obtain accurate orbital elements. However, it is possible to use such observations to statistically characterize the small object environment. A telescope pointed at a particular spot could potentially see objects in a number of different orbits. Inevitably, when looking at one region for certain types of orbits, there are objects in other types of orbits that cannot be seen. Observation campaigns are designed with these limitations in mind and are set up to span a number of regions of the sky, making it possible to sample all potential orbits under consideration. Each orbit is not seen with the same probability, however, so there are observation biases intrinsic to any observation campaign. Fortunately, it is possible to remove such biases and reconstruct a meaningful estimate of the statistical orbit populations of small objects in GEO. This information, in turn, can be used to investigate the nature of debris sources and to characterize the risk to GEO spacecraft. This paper describes these statistical tools and presents estimates of small object GEO populations.

  10. Independent Orbiter Assessment (IOA): Analysis of the orbital maneuvering system

    NASA Technical Reports Server (NTRS)

    Prust, C. D.; Paul, D. J.; Burkemper, V. J.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbital Maneuvering System (OMS) hardware are documented. The OMS provides the thrust to perform orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. The OMS is housed in two independent pods located one on each side of the tail and consists of the following subsystems: Helium Pressurization; Propellant Storage and Distribution; Orbital Maneuvering Engine; and Electrical Power Distribution and Control. The IOA analysis process utilized available OMS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluted and analyzed for possible failure modes and effects. Criticality was asigned based upon the severity of the effect for each failure mode.

  11. On-Orbit Software Analysis

    NASA Technical Reports Server (NTRS)

    Moran, Susanne I.

    2004-01-01

    The On-Orbit Software Analysis Research Infusion Project was done by Intrinsyx Technologies Corporation (Intrinsyx) at the National Aeronautics and Space Administration (NASA) Ames Research Center (ARC). The Project was a joint collaborative effort between NASA Codes IC and SL, Kestrel Technology (Kestrel), and Intrinsyx. The primary objectives of the Project were: Discovery and verification of software program properties and dependencies, Detection and isolation of software defects across different versions of software, and Compilation of historical data and technical expertise for future applications

  12. STATISTICAL ANALYSIS OF A DETERMINISTIC STOCHASTIC ORBIT

    SciTech Connect

    Kaufman, Allan N.; Abarbanel, Henry D.I.; Grebogi, Celso

    1980-05-01

    If the solution of a deterministic equation is stochastic (in the sense of orbital instability), it can be subjected to a statistical analysis. This is illustrated for a coded orbit of the Chirikov mapping. Statistical dependence and the Markov assumption are tested. The Kolmogorov-Sinai entropy is related to the probability distribution for the orbit.

  13. Collisional cascading - The limits of population growth in low earth orbit

    NASA Technical Reports Server (NTRS)

    Kessler, Donald J.

    1991-01-01

    Random collisions between made-made objects in earth orbit will lead to a significant source of orbital debris, but there are a number of uncertainties in these models, and additional analysis and data are required to fully characterize the future environment. However, the nature of these uncertainties are such that while the future environment is uncertain, the fact that collisions will control the future environment is less uncertain. The data that already exist is sufficient to show that cascading collisions will control the future debris environment with no, or very minor increases in the current low-earth-orbit population. Two populations control this process: explosion fragments and expended rocket bodies and payloads. Practices are already changing to limit explosions in low earth orbit; it is necessary to begin limiting the number of expended rocket bodies and payloads in orbit.

  14. Disentangling satellite galaxy populations using orbit tracking in simulations

    NASA Astrophysics Data System (ADS)

    Oman, Kyle A.; Hudson, Michael J.; Behroozi, Peter S.

    2013-05-01

    Physical processes regulating star formation in satellite galaxies represent an area of ongoing research, but the projected nature of observed coordinates makes separating different populations of satellites (with different processes at work) difficult. The orbital history of a satellite galaxy leads to its present-day phase space coordinates; we can also work backwards and use these coordinates to statistically infer information about the orbital history. We use merger trees from the MultiDark Run 1 N-body simulation to compile a catalogue of the orbits of satellite haloes in cluster environments. We parametrize the orbital history by the time since crossing within 2.5 rvir of the cluster centre and use our catalogue to estimate the probability density over a range of this parameter given a set of present-day projected (i.e. observable) phase space coordinates. We show that different populations of satellite haloes, e.g. infalling, backsplash and virialized, occupy distinct regions of phase space and semidistinct regions of projected phase space. This will allow us to probabilistically determine the time since infall of a large sample of observed satellite galaxies, and ultimately to study the effect of orbital history on star formation history (the topic of a future paper). We test the accuracy of our method and find that we can reliably recover this time within ±2.58 Gyr in 68 per cent of cases by using all available phase space coordinate information, compared to ±2.64 Gyr using only position coordinates and ±3.10 Gyr guessing `blindly', i.e. using no coordinate information, but with knowledge of the overall distribution of infall times. In some regions of phase space, the accuracy of the infall time estimate improves to ±1.85 Gyr. Although we focus on time since infall, our method is easily generalizable to other orbital parameters (e.g. pericentric distance and time).

  15. Orbital Analysis for Near-Earth Objects

    NASA Technical Reports Server (NTRS)

    Yeomans, D. K.; Chodas, P. W.

    1995-01-01

    For recently discovered Near-Earth Objects (NEO) two body computations can be used to determine the minimum distance between the object's orbit and that of the Earth. Determinations can then be made for potential near-term threats to the Earth. This preliminary orbit analysis must be followed with planetary perturbation computations of the object's future motion to predict actual close Earth approaches.

  16. Statistical Estimation of Orbital Debris Populations with a Spectrum of Object Size

    NASA Technical Reports Server (NTRS)

    Xu, Y. -l; Horstman, M.; Krisko, P. H.; Liou, J. -C; Matney, M.; Stansbery, E. G.; Stokely, C. L.; Whitlock, D.

    2008-01-01

    Orbital debris is a real concern for the safe operations of satellites. In general, the hazard of debris impact is a function of the size and spatial distributions of the debris populations. To describe and characterize the debris environment as reliably as possible, the current NASA Orbital Debris Engineering Model (ORDEM2000) is being upgraded to a new version based on new and better quality data. The data-driven ORDEM model covers a wide range of object sizes from 10 microns to greater than 1 meter. This paper reviews the statistical process for the estimation of the debris populations in the new ORDEM upgrade, and discusses the representation of large-size (greater than or equal to 1 m and greater than or equal to 10 cm) populations by SSN catalog objects and the validation of the statistical approach. Also, it presents results for the populations with sizes of greater than or equal to 3.3 cm, greater than or equal to 1 cm, greater than or equal to 100 micrometers, and greater than or equal to 10 micrometers. The orbital debris populations used in the new version of ORDEM are inferred from data based upon appropriate reference (or benchmark) populations instead of the binning of the multi-dimensional orbital-element space. This paper describes all of the major steps used in the population-inference procedure for each size-range. Detailed discussions on data analysis, parameter definition, the correlation between parameters and data, and uncertainty assessment are included.

  17. Space Shuttle Orbiter windshield bird impact analysis

    NASA Technical Reports Server (NTRS)

    Edelstein, Karen S.; Mccarty, Robert E.

    1988-01-01

    The NASA Space Shuttle Orbiter's windshield employs three glass panes separated by air gaps. The brittleness of the glass offers much less birdstrike energy-absorption capability than the laminated polycarbonate windshields of more conventional aircraft; attention must accordingly be given to the risk of catastrophic bird impact, and to methods of strike prevention that address bird populations around landing sites rather than the modification of the window's design. Bird populations' direct reduction, as well as careful scheduling of Orbiter landing times, are suggested as viable alternatives. The question of birdstrike-resistant glass windshield design for hypersonic aerospacecraft is discussed.

  18. Modeling of the Orbital Debris Population of RORSAT Sodium-Potassium Droplets

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Krisko, P. H.; Matney, Mark; Stansbery, E. G.

    2010-01-01

    A large population resident in the orbital debris environment is composed of eutectic sodium-potassium (NaK) droplets, released during the reactor core ejection of 16 nuclear-powered Radar Ocean Reconnaissance Satellites (RORSATs) launched in the 1980s by the former Soviet Union. These electrically conducting RORSAT debris objects are spherical in shape, generating highly polarized radar returns. Their diameters are mostly in the centimeter and millimeter size regimes. Since the Space Surveillance Network catalog is limited to objects greater than 5 cm in low Earth orbit, our current knowledge about this special class of orbital debris relies largely on the analysis of Haystack radar data. This paper elaborates the simulation of the RORSAT debris populations in the new NASA Orbital Debris Engineering Model ORDEM2010, which replaces ORDEM2000. The estimation of the NaK populations uses the NASA NaK-module as a benchmark. It follows the general statistical approach to developing all other ORDEM2010-required LEO populations (for various types of debris and across a wide range of object sizes). This paper describes, in detail, each major step in the NaK-population derivation, including a specific discussion on the conversion between Haystack-measured radar-cross-sections and object-size distribution for the NaK droplets. Modeling results show that the RORSAT debris population is stable for the time period under study and that Haystack data sets are fairly consistent over the observations of multiple years.

  19. Theoretical analysis (NBO, NPA, Mulliken Population Method) and molecular orbital studies (hardness, chemical potential, electrophilicity and Fukui function analysis) of (E)-2-((4-hydroxy-2-methylphenylimino)methyl)-3-methoxyphenol

    NASA Astrophysics Data System (ADS)

    Demircioğlu, Zeynep; Kaştaş, Çiğdem Albayrak; Büyükgüngör, Orhan

    2015-07-01

    The molecular structure and spectroscopic properties of (E)-2-((4-hydroxy-2-methylphenylimino)methyl)-3-methoxyphenol, were characterized by X-ray diffraction, FT-IR and UV-Vis spectroscopy. All of theoretical calculations and optimized geometric parameters have been calculated by using density functional theory (DFT) with hybrid method B3LYP by 6-31G(d,p) basis set. The title compound of C15H15N1O3 have been analyzed according to electronic and energetics behaviors for enol-imine and keto-amine tautomers. Both these tautomers engender six-membered ring due to intramolecular hydrogen bonded interactions. Two types of intramolecular hydrogen bonds (a) strong O-H⋯N interactions in enol-imine form and (b) N-H⋯O interactions in keto-amine form are compared particularly. The theoretical vibrational frequencies have been found in good agreement with the corresponding experimental data. A study on the electronic and optical properties, absorption wavelengths, excitation energy, dipole moment, molecular electrostatic potential (MEP) and frontier molecular orbital energies are performed using DFT method. Additionally, geometry optimizations in solvent media were performed with the same level of theory by the polarizable continuum model (PCM). The effect of solvents on the tautomeric stability has been investigated. Mulliken Population Method and natural population analysis (NPA) have been studied. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The local reactivity of the molecule has been studied using the Fukui function. NLO properties related to polarizability and hyperpolarizability are also discussed.

  20. Satellite orbits design using frequency analysis

    NASA Astrophysics Data System (ADS)

    Noullez, A.; Tsiganis, K.; Tzirti, S.

    2015-07-01

    We present here a new method for the efficient computation of periodic orbits, which are of particular interest for low-altitude satellite orbits design in high degree/order, non-axisymmetric gravity models. Our method consists of an iterative filtering scheme, that is itself based on 'Prony's method' of frequency analysis, and is independent of the complexity of the gravity model. Applying this method to the case of a low-altitude lunar orbiter, we show that it converges rapidly, in all models and for all values of altitude and initial inclination studied. Thus, as demonstrated below, one could use it to correct the initial conditions of a desired mission orbit - usually defined within the framework of a simplified model (e.g. the 'J2 problem') - ensuring minimal orbital eccentricity variations and, for very low altitudes, collision avoidance. At the same time, an accurate quasi-periodic decomposition of the orbit is computed, giving a measure of the periodic fluctuations of the orbital parameters.

  1. Parallel Computation of Orbit Determination for Space Debris Population

    NASA Astrophysics Data System (ADS)

    Olmedo, Estrella; Sanchez-Ortiz, Noelia; Ramos-Lerate, Mercedes

    2009-03-01

    In this work we present an algorithm for computing Orbit Determination for Space Debris population. The method presents a high degree of parallelism. That means that the number of available computers divides the computational effort. The context of this work and the later scope is to have the capability of cataloguing and correlating the Space Debris population. In this sense, as better the accuracy provided by the orbit determination is, more accurate will be the estimation of the state vectors corresponding to the debris objects and better will be the accuracy of the future catalogue of Space Debris. As more objects we can determinate the corresponding orbit, more complete will be the future catalogue. Therefore numerical tools for orbit determination are a key point in the development of a future ESSAS. The first time that a new object is observed, six measurements (these measurements may come from RADAR, Ground Based Telescope or Space Based Telescope) are required for computing an Initial Orbit Determination (IOD). After that, the Initial Estimated State Vector (IESV) is improved within the next-coming measurement. The idea of this method is the following. From six initial measurements, we compute the IOD following the same ideas of [1]. We compute also the initial knowledge covariance matrix (IKCM) corresponding to the IESV. In general, the numerical error of the IOD is too big for processing the following measurements with a conventional numerical filter (like the Square Root Information Filter (SRIF)). The problem is that the improvement of the accuracy in the IOD is not an easy task in those cases with large initial error. However the computed IKCM give a realistic approximation of the committed error in the IOD. The proposed algorithm uses the IKCM for generating a cloud of IESVs. All the IESV inside the cloud are processed with a new and much smaller IKCM by using SRIF. In such a way that the ones that are close enough to the real state vector (and thus

  2. James Webb Space Telescope Orbit Determination Analysis

    NASA Technical Reports Server (NTRS)

    Yoon, Sungpil; Rosales, Jose; Richon, Karen

    2014-01-01

    The James Webb Space Telescope (JWST) is designed to study and answer fundamental astrophysical questions from an orbit about the Sun-Earth/Moon L2 libration point, 1.5 million km away from Earth. This paper describes the results of an orbit determination (OD) analysis of the JWST mission emphasizing the challenges specific to this mission in various mission phases. Three mid-course correction (MCC) maneuvers during launch and early orbit phase and transfer orbit phase are required for the spacecraft to reach L2. These three MCC maneuvers are MCC-1a at Launch+12 hours, MCC-1b at L+2.5 days and MCC-2 at L+30 days. Accurate OD solutions are needed to support MCC maneuver planning. A preliminary analysis shows that OD performance with the given assumptions is adequate to support MCC maneuver planning. During the nominal science operations phase, the mission requires better than 2 cm/sec velocity estimation performance to support stationkeeping maneuver planning. The major challenge to accurate JWST OD during the nominal science phase results from the unusually large solar radiation pressure force acting on the huge sunshield. Other challenges are stationkeeping maneuvers at 21-day intervals to keep JWST in orbit around L2, frequent attitude reorientations to align the JWST telescope with its targets and frequent maneuvers to unload momentum accumulated in the reaction wheels. Monte Carlo analysis shows that the proposed OD approach can produce solutions that meet the mission requirements.

  3. Characterizing the population of Asteroids in Cometary Orbits (ACOs)

    NASA Astrophysics Data System (ADS)

    Tancredi, Gonzalo; Licandro, Javier; Alí-Lagoa, Victor; Martino, Silvia; Vieira Monteiro, Filipe; Silva, Jose Sergio; Lazzaro, Daniela

    2015-08-01

    The classification criterion between asteroids and comets has evolved in recent decades, but the main phenomenological distinction remains unchanged: comets are active objects as they present gas and dust ejection from the surface at some point of their orbits, while asteroids are inert objects as they do not show any kind of large scale gas and dust ejection.To identify the transitional objects several classification schemes based on the orbital elements have been used. They are usually based on the Tisserand’s parameter (TJ). Tancredi (2014) presents a much more restrictive criterion to identify ACOs that ensured that the objects have a dynamical evolution similar to the population of periodic comets. After applying the criteriaa to the sample of over half a million asteroids already discovered, we obtain 316 ACOs that are further classified in subclasses similar to the cometary classification: 203 objects belong to the Jupiter Family group; 72 objects are classified as Centaurs; and 56 objects have Halley Type Orbits (also known as Damocloids). These are the best-known extinct/dormant comets candidates from a dynamical point of view.We study the physical properties of this sample of ACOs. Two results will be presented:- We look for the ACOs detected by the NASA’s WISE and by fitting a thermal model to their observations, we derive: the effective diameter, beaming parameter and the visible geometric albedo, using the method described in Al-Lagoa et al (2013). We obtain these parameters for 37 of 203 ACOs in JFC orbits and 13 of 56 Damocloids. We also compute the Cumulative Size Distribution (CSDs) of these populations and compare them with the CSDs of JF Comets and Centaurs.- We have been monitoring the observable ACOs since 12/2014 up to 06/2015. Every other month we select all the ACOs with elongations >90deg and estimated magnitudes V<21. We try to observe them with the 1m IMPACTON telescope of the Observatório Astronômico do Sertão de Itaparica (OASI

  4. Stochastic Analysis of Orbital Lifetimes of Spacecraft

    NASA Technical Reports Server (NTRS)

    Sasamoto, Washito; Goodliff, Kandyce; Cornelius, David

    2008-01-01

    A document discusses (1) a Monte-Carlo-based methodology for probabilistic prediction and analysis of orbital lifetimes of spacecraft and (2) Orbital Lifetime Monte Carlo (OLMC)--a Fortran computer program, consisting of a previously developed long-term orbit-propagator integrated with a Monte Carlo engine. OLMC enables modeling of variances of key physical parameters that affect orbital lifetimes through the use of probability distributions. These parameters include altitude, speed, and flight-path angle at insertion into orbit; solar flux; and launch delays. The products of OLMC are predicted lifetimes (durations above specified minimum altitudes) for the number of user-specified cases. Histograms generated from such predictions can be used to determine the probabilities that spacecraft will satisfy lifetime requirements. The document discusses uncertainties that affect modeling of orbital lifetimes. Issues of repeatability, smoothness of distributions, and code run time are considered for the purpose of establishing values of code-specific parameters and number of Monte Carlo runs. Results from test cases are interpreted as demonstrating that solar-flux predictions are primary sources of variations in predicted lifetimes. Therefore, it is concluded, multiple sets of predictions should be utilized to fully characterize the lifetime range of a spacecraft.

  5. Orbital and Geodetic Error Analysis

    NASA Technical Reports Server (NTRS)

    Felsentreger, T.; Maresca, P.; Estes, R.

    1985-01-01

    Results that previously required several runs determined in more computer-efficient manner. Multiple runs performed only once with GEODYN and stored on tape. ERODYN then performs matrix partitioning and linear algebra required for each individual error-analysis run.

  6. James Webb Space Telescope Orbit Determination Analysis

    NASA Technical Reports Server (NTRS)

    Yoon, Sungpil; Rosales, Jose; Richon, Karen

    2014-01-01

    The James Webb Space Telescope (JWST) is designed to study and answer fundamental astrophysical questions from an orbit about the Sun-EarthMoon L2 libration point, 1.5 million km away from Earth. Three mid-course correction (MCC) maneuvers during launch and early orbit phase and transfer orbit phase are required for the spacecraft to reach L2. These three MCC maneuvers are MCC-1a at Launch+12 hours, MCC-1b at L+2.5 days and MCC-2 at L+30 days. Accurate orbit determination (OD) solutions are needed to support MCC maneuver planning. A preliminary analysis shows that OD performance with the given assumptions is adequate to support MCC maneuver planning. During the nominal science operations phase, the mission requires better than 2 cmsec velocity estimation performance to support stationkeeping maneuver planning. The major challenge to accurate JWST OD during the nominal science phase results from the unusually large solar radiation pressure force acting on the huge sunshield. Other challenges are stationkeeping maneuvers at 21-day intervals to keep JWST in orbit around L2, frequent attitude reorientations to align the JWST telescope with its targets and frequent maneuvers to unload momentum accumulated in the reaction wheels. Monte Carlo analysis shows that the proposed OD approach can produce solutions that meet the mission requirements.

  7. Subsatellite Orbital Analysis Program (SOAP) user's guide

    NASA Technical Reports Server (NTRS)

    Castle, K. G.; Voss, J. M.; Gibson, J. S.

    1981-01-01

    The features and use of the subsatellite operational analysis are examined. The model simulates several Earth-orbiting vehicles, their pilots, control systems, and interaction with the environment. The use of the program, input and output capabilities, executive structures, and properties of the vehicles and environmental effects which it models are described.

  8. Modeling of LEO Orbital Debris Populations in Centimeter and Millimeter Size Regimes

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Hill, . M.; Horstman, M.; Krisko, P. H.; Liou, J.-C.; Matney, M.; Stansbery, E. G.

    2010-01-01

    The building of the NASA Orbital Debris Engineering Model, whether ORDEM2000 or its recently updated version ORDEM2010, uses as its foundation a number of model debris populations, each truncated at a minimum object-size ranging from 10 micron to 1 m. This paper discusses the development of the ORDEM2010 model debris populations in LEO (low Earth orbit), focusing on centimeter (smaller than 10 cm) and millimeter size regimes. Primary data sets used in the statistical derivation of the cm- and mm-size model populations are from the Haystack radar operated in a staring mode. Unlike cataloged objects of sizes greater than approximately 10 cm, ground-based radars monitor smaller-size debris only in a statistical manner instead of tracking every piece. The mono-static Haystack radar can detect debris as small as approximately 5 mm at moderate LEO altitudes. Estimation of millimeter debris populations (for objects smaller than approximately 6 mm) rests largely on Goldstone radar measurements. The bi-static Goldstone radar can detect 2- to 3-mm objects. The modeling of the cm- and mm-debris populations follows the general approach to developing other ORDEM2010-required model populations for various components and types of debris. It relies on appropriate reference populations to provide necessary prior information on the orbital structures and other important characteristics of the debris objects. NASA's LEO-to-GEO Environment Debris (LEGEND) model is capable of furnishing such reference populations in the desired size range. A Bayesian statistical inference process, commonly adopted in ORDEM2010 model-population derivations, changes a priori distribution into a posteriori distribution and thus refines the reference populations in terms of data. This paper describes key elements and major steps in the statistical derivations of the cm- and mm-size debris populations and presents results. Due to lack of data for near 1-mm sizes, the model populations of 1- to 3.16-mm

  9. NGC1300 dynamics - III. Orbital analysis

    NASA Astrophysics Data System (ADS)

    Patsis, P. A.; Kalapotharakos, C.; Grosbøl, P.

    2010-10-01

    We present the orbital analysis of four response models that succeed in reproducing morphological features of NGC1300. Two of them assume a planar (2D) geometry with Ωp = 22 and 16kms-1kpc-1, respectively. The two others assume a cylindrical (thick) disc and rotate with the same pattern speeds as the 2D models. These response models reproduce most successfully main morphological features of NGC1300 among a large number of models, as became evident in a previous study. Our main result is the discovery of three new dynamical mechanisms that can support structures in a barred spiral grand design system. These mechanisms are presented in characteristic cases, where these dynamical phenomena take place. They refer first to the support of a strong bar, of ansae type, almost solely by chaotic orbits, then to the support of spirals by chaotic orbits that for a certain number of pattern revolutions follow an n:1 (n = 7,8) morphology, and finally to the support of spiral arms by a combination of orbits trapped around L4, 5 and sticky chaotic orbits with the same Jacobi constant. We have encountered these dynamical phenomena in a large fraction of the cases we studied as we varied the parameters of our general models, without forcing in some way their appearance. This suggests that they could be responsible for the observed morphologies of many barred spiral galaxies. Comparing our response models among themselves we find that the NGC1300 morphology is best described by a thick-disc model for the bar region and a 2D disc model for the spirals, with both components rotating with the same pattern speed Ωp = 16km s-1kpc-1. In such a case, the whole structure is included inside the corotation of the system. The bar is supported mainly by regular orbits, while the spirals are supported by chaotic orbits. Based on observations collected at the European Southern Observatory, Chile: programme ESO 69.A-0021. E-mail: patsis@academyofathens.gr (PAP); ckalapot@phys.uoa.gr (CK

  10. Orion Orbit Control Design and Analysis

    NASA Technical Reports Server (NTRS)

    Jackson, Mark; Gonzalez, Rodolfo; Sims, Christopher

    2007-01-01

    The analysis of candidate thruster configurations for the Crew Exploration Vehicle (CEV) is presented. Six candidate configurations were considered for the prime contractor baseline design. The analysis included analytical assessments of control authority, control precision, efficiency and robustness, as well as simulation assessments of control performance. The principles used in the analytic assessments of controllability, robustness and fuel performance are covered and results provided for the configurations assessed. Simulation analysis was conducted using a pulse width modulated, 6 DOF reaction system control law with a simplex-based thruster selection algorithm. Control laws were automatically derived from hardware configuration parameters including thruster locations, directions, magnitude and specific impulse, as well as vehicle mass properties. This parameterized controller allowed rapid assessment of multiple candidate layouts. Simulation results are presented for final phase rendezvous and docking, as well as low lunar orbit attitude hold. Finally, on-going analysis to consider alternate Service Module designs and to assess the pilot-ability of the baseline design are discussed to provide a status of orbit control design work to date.

  11. Populating Stellar Orbits inside a Rotating, Gaseous Bar

    NASA Astrophysics Data System (ADS)

    Barnes, Eric I.; Tohline, Joel E.

    2001-04-01

    In an effort to understand better the formation and evolution of barred galaxies, we have examined the properties of equatorial orbits in the effective potential of one specific model of a rapidly rotating, steady state gasdynamical bar that has been constructed via a self-consistent hydrodynamical simulation. At a given value of the Jacobi constant, roughly half of all test particles (stars) that are injected into the equatorial plane of this potential follow quasi-ergodic orbits; most regular prograde orbits have an overall ``bow tie'' shape; and some trace out trajectories that resemble the x4 family of regular, retrograde orbits. The bow tie orbits appear to be related to the 4/1 orbit family discussed by Contopoulous in 1988, but particles moving along a bow tie orbit pass very close to the center of the bar twice each orbit. Unlike the barlike configurations that previously have been constructed using dissipationless, N-body simulation techniques, the effective potential of our gasdynamical bar is very shallow and generally does not support the x1 family of orbits. If primordial galaxies evolve to a rapidly rotating barlike configuration before a significant amount of star formation has taken place and then stars form from the gas that makes up the bar, the initial stellar distribution function should consist of orbits that are (1) supported by the gaseous barlike potential and (2) restricted to have initial conditions dictated by the gasdynamics of the bar. With this ``restriction hypothesis'' in mind, we propose that stellar dynamical systems that form from gaseous bars will have characteristics that differ significantly from systems that form from a bisymmetric instability in an initially axisymmetric stellar system. Since bow tie orbits are preferred over x1 orbits, for example, such systems should have a more boxy or peanut shape when seen face-on there will be a mechanism for funneling material more directly into the center of the galaxy; and, near the

  12. Harmonic decomposition of orbit data for multipole analysis

    SciTech Connect

    Yang, M.-J.; /Fermilab

    2005-05-01

    This paper describes a simple analysis procedure that transforms a set of beamline orbit data into a set of harmonic orbits of first, second, and third order or higher. Each harmonic orbit can be studied individually to identify errors of the specific order with minimum interference from other orders. Effectively these are orbits caused by kicks, due to harmonic errors, propagated through linear lattice. Examples from accelerator study will be presented. The application and inherent limitations of this analysis procedure are discussed.

  13. Reentry analysis for low Earth orbiting spacecraft

    NASA Astrophysics Data System (ADS)

    Newman, Lauri Kraft; Folta, David C.; Ross, Brian P.; Bouslog, Stanley A.

    As a result of recent National Aeronautics and Space Administration (NASA) Management Instruction (NMI), NASA spacecraft programs must limit orbital debris by design and/or by operational procedures. To fulfill this requirement, spacecraft may be required to be removed from their operational orbit after mission completion. Spacecraft disposal by atmospheric reentry is a means to accomplish this task. To assess the risk to man, an analysis must be done to determine which parts of the spacecraft are likely to survive a reentry of the Earth's atmosphere and where those parts will land. These issues are currently being examined for the Earth Observing System (EOS-AM1). The Johnson Space Center (JSC) Aeroscience Branch, supported by the Lockheed Engineering and Sciences Co., has developed a tool which permits the analysis of the thermal effects of reentry on individual spacecraft components to determine which components are expected to survive reentry. This paper presents an examination of the burnup and reentry of EOS-AM1 and describes a method for other spacecraft to use in analyzing similar reentry issues.

  14. Mars Reconnaissance Orbiter Uplink Analysis Tool

    NASA Technical Reports Server (NTRS)

    Khanampompan, Teerapat; Gladden, Roy; Fisher, Forest; Hwang, Pauline

    2008-01-01

    This software analyzes Mars Reconnaissance Orbiter (MRO) orbital geometry with respect to Mars Exploration Rover (MER) contact windows, and is the first tool of its kind designed specifically to support MRO-MER interface coordination. Prior to this automated tool, this analysis was done manually with Excel and the UNIX command line. In total, the process would take approximately 30 minutes for each analysis. The current automated analysis takes less than 30 seconds. This tool resides on the flight machine and uses a PHP interface that does the entire analysis of the input files and takes into account one-way light time from another input file. Input flies are copied over to the proper directories and are dynamically read into the tool s interface. The user can then choose the corresponding input files based on the time frame desired for analysis. After submission of the Web form, the tool merges the two files into a single, time-ordered listing of events for both spacecraft. The times are converted to the same reference time (Earth Transmit Time) by reading in a light time file and performing the calculations necessary to shift the time formats. The program also has the ability to vary the size of the keep-out window on the main page of the analysis tool by inputting a custom time for padding each MRO event time. The parameters on the form are read in and passed to the second page for analysis. Everything is fully coded in PHP and can be accessed by anyone with access to the machine via Web page. This uplink tool will continue to be used for the duration of the MER mission's needs for X-band uplinks. Future missions also can use the tools to check overflight times as well as potential site observation times. Adaptation of the input files to the proper format, and the window keep-out times, would allow for other analyses. Any operations task that uses the idea of keep-out windows will have a use for this program.

  15. A finite-element analysis model of orbital biomechanics.

    PubMed

    Schutte, Sander; van den Bedem, Sven P W; van Keulen, Fred; van der Helm, Frans C T; Simonsz, Huibert J

    2006-05-01

    To reach a better understanding of the suspension of the eye in the orbit, an orbital mechanics model based upon finite-element analysis (FEA) has been developed. The FEA model developed contains few prior assumptions or constraints (e.g., the position of the eye in the orbit), allowing modeling of complex three-dimensional tissue interactions; unlike most current models of eye motility. Active eye movements and forced ductions were simulated and showed that the supporting action of the orbital fat plays an important role in the suspension of the eye in the orbit and in stabilization of rectus muscle paths. PMID:16413594

  16. Ionospheric refraction effects on orbit determination using the orbit determination error analysis system

    NASA Technical Reports Server (NTRS)

    Yee, C. P.; Kelbel, D. A.; Lee, T.; Dunham, J. B.; Mistretta, G. D.

    1990-01-01

    The influence of ionospheric refraction on orbit determination was studied through the use of the Orbit Determination Error Analysis System (ODEAS). The results of a study of the orbital state estimate errors due to the ionospheric refraction corrections, particularly for measurements involving spacecraft-to-spacecraft tracking links, are presented. In current operational practice at the Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF), the ionospheric refraction effects on the tracking measurements are modeled in the Goddard Trajectory Determination System (GTDS) using the Bent ionospheric model. While GTDS has the capability of incorporating the ionospheric refraction effects for measurements involving ground-to-spacecraft tracking links, such as those generated by the Ground Spaceflight Tracking and Data Network (GSTDN), it does not have the capability to incorporate the refraction effects for spacecraft-to-spacecraft tracking links for measurements generated by the Tracking and Data Relay Satellite System (TDRSS). The lack of this particular capability in GTDS raised some concern about the achievable accuracy of the estimated orbit for certain classes of spacecraft missions that require high-precision orbits. Using an enhanced research version of GTDS, some efforts have already been made to assess the importance of the spacecraft-to-spacecraft ionospheric refraction corrections in an orbit determination process. While these studies were performed using simulated data or real tracking data in definitive orbit determination modes, the study results presented here were obtained by means of covariance analysis simulating the weighted least-squares method used in orbit determination.

  17. Orbit analysis for coastal zone oceanography observations.

    NASA Technical Reports Server (NTRS)

    Harrison, E. F.; Green, R. N.

    1973-01-01

    A study has been performed to define the orbital characteristics of a satellite dedicated to monitoring the coastal zones of the United States. The primary area of coverage is the east coast with secondary coverage of the west coast. Since no one orbital inclination fits both coasts, the inclination was determined by the east coast to be 63 deg. This inclination was found to give better coverage of the east coast than either its retrograde counterpart or a sun synchronous orbit. The two coasts require quite different orbits to maximize the coverage. The use of a small propulsive maneuver could be used to compromise the coverage between the two coastlines and change from one type orbit to the other.

  18. NASA Orbital Debris Large-Object Baseline Population in ORDEM 3.0

    NASA Technical Reports Server (NTRS)

    Krisco, Paula H.; Vavrin, A. B.; Anz-Meador, P. D.

    2013-01-01

    The NASA Orbital Debris Program Office (ODPO) has created and validated high fidelity populations of the debris environment for the latest Orbital Debris Engineering Model (ORDEM 3.0). Though the model includes fluxes of objects 10 um and larger, this paper considers particle fluxes for 1 cm and larger debris objects from low Earth orbit (LEO) through Geosynchronous Transfer Orbit (GTO). These are validated by several reliable radar observations through the Space Surveillance Network (SSN), Haystack, and HAX radars. ORDEM 3.0 populations were designed for the purpose of assisting, debris researchers and sensor developers in planning and testing. This environment includes a background derived from the LEO-to-GEO ENvironment Debris evolutionary model (LEGEND) with a Bayesian rescaling as well as specific events such as the FY-1C anti-satellite test, the Iridium 33/Cosmos 2251 accidental collision, and the Soviet/Russian Radar Ocean Reconnaissance Satellite (RORSAT) sodium-potassium droplet releases. The environment described in this paper is the most realistic orbital debris population larger than 1 cm, to date. We describe derivations of the background population and added specific populations. We present sample validation charts of our 1 cm and larger LEO population against Space Surveillance Network (SSN), Haystack, and HAX radar measurements.

  19. Population Analysis: Communicating in Context

    NASA Technical Reports Server (NTRS)

    Rajulu, Sudhakar; Thaxton, Sherry

    2008-01-01

    Providing accommodation to a widely varying user population presents a challenge to engineers and designers. It is often even difficult to quantify who is accommodated and who is not accommodated by designs, especially for equipment with multiple critical anthropometric dimensions. An approach to communicating levels of accommodation referred to as population analysis applies existing human factors techniques in novel ways. This paper discusses the definition of population analysis as well as major applications and case studies. The major applications of population analysis consist of providing accommodation information for multivariate problems and enhancing the value of feedback from human-in-the-loop testing. The results of these analyses range from the provision of specific accommodation percentages of the user population to recommendations of design specifications based on quantitative data. Such feedback is invaluable to designers and results in the design of products that accommodate the intended user population.

  20. Asteroid orbital error analysis: Theory and application

    NASA Technical Reports Server (NTRS)

    Muinonen, K.; Bowell, Edward

    1992-01-01

    We present a rigorous Bayesian theory for asteroid orbital error estimation in which the probability density of the orbital elements is derived from the noise statistics of the observations. For Gaussian noise in a linearized approximation the probability density is also Gaussian, and the errors of the orbital elements at a given epoch are fully described by the covariance matrix. The law of error propagation can then be applied to calculate past and future positional uncertainty ellipsoids (Cappellari et al. 1976, Yeomans et al. 1987, Whipple et al. 1991). To our knowledge, this is the first time a Bayesian approach has been formulated for orbital element estimation. In contrast to the classical Fisherian school of statistics, the Bayesian school allows a priori information to be formally present in the final estimation. However, Bayesian estimation does give the same results as Fisherian estimation when no priori information is assumed (Lehtinen 1988, and reference therein).

  1. Orbit Determination Analysis Utilizing Radiometric and Laser Ranging Measurements for GPS Orbit

    NASA Technical Reports Server (NTRS)

    Welch, Bryan W.

    2007-01-01

    While navigation systems for the determination of the orbit of the Global Position System (GPS) have proven to be very effective, the current issues involve lowering the error in the GPS satellite ephemerides below their current level. In this document, the results of an orbit determination covariance assessment are provided. The analysis is intended to be the baseline orbit determination study comparing the benefits of adding laser ranging measurements from various numbers of ground stations. Results are shown for two starting longitude assumptions of the satellite location and for nine initial covariance cases for the GPS satellite state vector.

  2. Effects of Orbital Lifetime Reduction on the Long-Term Earth Satellite Population as Modeled by EVOLVE 4.0

    NASA Technical Reports Server (NTRS)

    Krisko, Paula H.; Opiela, John N.; Liou, Jer-Chyi; Anz-Meador, Phillip D.; Theall, Jeffrey R.

    1999-01-01

    The latest update of the NASA orbital debris environment model, EVOLVE 4.0, has been used to study the effect of various proposed debris mitigation measures, including the NASA 25-year guideline. EVOLVE 4.0, which includes updates of the NASA breakup, solar activity, and the orbit propagator models, a GEO analysis option, and non-fragmentation debris source models, allows for the statistical modeling and predicted growth of the particle population >1 mm in characteristic length in LEO and GEO orbits. The initial implementation of this &odel has been to study the sensitivity of the overall LEO debris environment to mitigation measures designed to limit the lifetime of intact objects in LEO orbits. The mitigation measures test matrix for this study included several commonly accepted testing schemes, i.e., the variance of the maximum LEO lifetime from 10 to 50 years, the date of the initial implementation of this policy, the shut off of all explosions at some specified date, and the inclusion of disposal orbits. All are timely studies in that all scenarios have been suggested by researchers and satellite operators as options for the removal of debris from LEO orbits.

  3. Feasibility analysis of cislunar flight using the Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Haynes, Davy A.

    1991-01-01

    A first order orbital mechanics analysis was conducted to examine the possibility of utilizing the Space Shuttle Orbiter to perform payload delivery missions to lunar orbit. In the analysis, the earth orbit of departure was constrained to be that of Space Station Freedom. Furthermore, no enhancements of the Orbiter's thermal protection system were assumed. Therefore, earth orbit insertion maneuvers were constrained to be all propulsive. Only minimal constraints were placed on the lunar orbits and no consideration was given to possible landing sites for lunar surface payloads. The various phases and maneuvers of the mission are discussed for both a conventional (Apollo type) and an unconventional mission profile. The velocity impulses needed, and the propellant masses required are presented for all of the mission maneuvers. Maximum payload capabilities were determined for both of the mission profiles examined. In addition, other issues relating to the feasibility of such lunar shuttle missions are discussed. The results of the analysis indicate that the Shuttle Orbiter would be a poor vehicle for payload delivery missions to lunar orbit.

  4. Resolving LDEF's flux distribution: Orbital (debris?) and natural meteoroid populations

    NASA Technical Reports Server (NTRS)

    Mcdonnell, J. A. M.

    1993-01-01

    A consistent methodology for the collation of data from both penetration and perforation experiments and from data in the Meteoroid and Debris Special Investigator Group (M-D SIG) data-base has led to the derivation of the average impact flux over LDEF's exposure history 1984-1990. Data are first presented for LDEF's N,S,E,W and Space faces ('offset' by 8 deg and 'tilted' by 1 deg respectively). A model fit is derived for ballistic limits of penetration from 1 micron to 1mm of aluminium target, corresponding to impactor masses from 10(exp -18) kg (for rho sub p = 2g/cu cm) to 10(exp -10) kg (for rho sub p = 1g/cu cm). A second order harmonic function is fitted to the N,S,E, and W fluxes to establish the angular distribution at regular size intervals; this fit is then used to provide 'corrected' data corresponding to fluxes applicable to true N,S,E,W and Space directions for a LEO 28.5 degree inclination orbit at a mean altitude of 465 km.

  5. Resolving LDEF's flux distribution: Orbital (debris?) and natural meteoroid populations

    NASA Astrophysics Data System (ADS)

    McDonnell, J. A. M.

    1993-03-01

    A consistent methodology for the collation of data from both penetration and perforation experiments and from data in the Meteoroid and Debris Special Investigator Group (M-D SIG) data-base has led to the derivation of the average impact flux over LDEF's exposure history 1984-1990. Data are first presented for LDEF's N,S,E,W and Space faces ('offset' by 8 deg and 'tilted' by 1 deg respectively). A model fit is derived for ballistic limits of penetration from 1 micron to 1mm of aluminium target, corresponding to impactor masses from 10-18 kg (for rhop = 2g/cu cm) to 10-10 kg (for rhop = 1g/cu cm). A second order harmonic function is fitted to the N,S,E, and W fluxes to establish the angular distribution at regular size intervals; this fit is then used to provide 'corrected' data corresponding to fluxes applicable to true N,S,E,W and Space directions for a LEO 28.5 degree inclination orbit at a mean altitude of 465 km.

  6. Instability of the Current Space Debris Population in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Maniwa, Kazuaki; Hanada, Toshiya; Kawamoto, Satomi

    Since the launch of Sputnik, orbital debris population continues to increase due to ongoing space activities, on-orbit explosions, and accidental collisions. In the future, it is expected that a great deal of fragments will be created by explosions and collisions. Thus, the number of space debris may increase exponentially (Kessler Syndrome). This paper analyzes the Kessler Syndrome using the Low Earth Orbital Debris Environmental Evolutionary Model (LEODEEM) developed at Kyushu University with collaboration from JAXA. The purpose of the study aims at understanding the issues related to space environment conservation. The results provide effective conditions of Active Debris Removal which is one of the space debris mitigation procedures.

  7. A clinical analysis of bilateral orbital fracture.

    PubMed

    Roh, Joon Ho; Jung, Jee Woong; Chi, Mijung

    2014-03-01

    Although bilateral orbital fracture can cause serious eyeball and facial skeletal problems, few reports have been issued on the topic. We analyzed the clinical features of bilateral orbital fracture by reviewing the medical records of 147 patients and compared bilateral and unilateral fractures by reviewing the literature.Bilateral orbital fracture was most common in men aged between 50 and 59 years. A traffic accident was the leading cause of trauma, and average time between trauma and surgery was 12.2 days. Bilateral medial fracture accompanied by nasal fracture accounted for the overwhelming majority, and impure blowout fracture in at least 1 eye occurred in 69.4% of the 147 patients. Associated ocular injuries seemed to be similar for bilateral and unilateral fracture. Thirty-five patients (23.8%) had other multiple traumas affecting other than the eyes, and this significantly increased the need for surgery (P < 0.05). Of the 48 patients who underwent surgery, including 4 cases of bilateral surgery, 21 patients who had ocular motility restriction with central diplopia within 30 degrees almost completely recovered. No significant relation between the timing of surgery and improvement was found. Although unilateral surgery was performed in most cases, facial asymmetry related to enophthalmos was unclear at 6 months postoperatively.In summary, bilateral orbital fracture was found to be clinically distinguishable from unilateral fracture in several aspects. We hope these findings provide a reference guide to the approach and management of bilateral orbital fracture. PMID:24514894

  8. Simulation of Micron-Sized Debris Populations in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Xu, Yu-Lin; Matney, Mark; Liou, J.-C.; Hyde, James; Prior, Thomas G.

    The update of ORDEM2000, the NASA Orbital Debris Engineering Model, to its new version -ORDEM2010, is nearly complete. As a part of the ORDEM upgrade, this paper addresses the simulation of micro-debris (greater than 10 µm and smaller than 1 mm in size) populations in low Earth orbit. The principal data used in the modeling of the micron-sized debris popu-lations are in-situ hypervelocity impact records, accumulated in post-flight damage surveys on the space-exposed surfaces of returned spacecrafts. The development of the micro-debris model populations follows the general approach to deriving other ORDEM2010-required input popu-lations for various components and types of debris. This paper describes the key elements and major steps in the statistical inference of the ORDEM2010 micro-debris populations. A crucial step is the construction of a degradation/ejecta source model to provide prior information on the micron-sized objects (such as orbital and object-size distributions). Another critical step is to link model populations with data, which is rather involved. It demands detailed information on area-time/directionality for all the space-exposed elements of a shuttle orbiter and damage laws, which relate impact damage with the physical properties of a projectile and impact con-ditions such as impact angle and velocity. Also needed are model-predicted debris fluxes as a function of object size and impact velocity from all possible directions. In spite of the very limited quantity of the available shuttle impact data, the population-derivation process is satis-factorily stable. Final modeling results obtained from shuttle window and radiator impact data are reasonably convergent and consistent, especially for the debris populations with object-size thresholds at 10 and 100 µm.

  9. Simulation of Micron-Sized Debris Populations in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Hyde, J. L.; Prior, T.; Matney, Mark

    2010-01-01

    The update of ORDEM2000, the NASA Orbital Debris Engineering Model, to its new version ORDEM2010, is nearly complete. As a part of the ORDEM upgrade, this paper addresses the simulation of micro-debris (greater than 10 m and smaller than 1 mm in size) populations in low Earth orbit. The principal data used in the modeling of the micron-sized debris populations are in-situ hypervelocity impact records, accumulated in post-flight damage surveys on the space-exposed surfaces of returned spacecrafts. The development of the micro-debris model populations follows the general approach to deriving other ORDEM2010-required input populations for various components and types of debris. This paper describes the key elements and major steps in the statistical inference of the ORDEM2010 micro-debris populations. A crucial step is the construction of a degradation/ejecta source model to provide prior information on the micron-sized objects (such as orbital and object-size distributions). Another critical step is to link model populations with data, which is rather involved. It demands detailed information on area-time/directionality for all the space-exposed elements of a shuttle orbiter and damage laws, which relate impact damage with the physical properties of a projectile and impact conditions such as impact angle and velocity. Also needed are model-predicted debris fluxes as a function of object size and impact velocity from all possible directions. In spite of the very limited quantity of the available shuttle impact data, the population-derivation process is satisfactorily stable. Final modeling results obtained from shuttle window and radiator impact data are reasonably convergent and consistent, especially for the debris populations with object-size thresholds at 10 and 100 m.

  10. Simulation of Micron-Sized Debris Populations in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Matney, M.; Liou, J.-C.; Hyde, J. L.; Prior, T. G.

    2010-01-01

    The update of ORDEM2000, the NASA Orbital Debris Engineering Model, to its new version . ORDEM2010, is nearly complete. As a part of the ORDEM upgrade, this paper addresses the simulation of micro-debris (greater than 10 micron and smaller than 1 mm in size) populations in low Earth orbit. The principal data used in the modeling of the micron-sized debris populations are in-situ hypervelocity impact records, accumulated in post-flight damage surveys on the space-exposed surfaces of returned spacecrafts. The development of the micro-debris model populations follows the general approach to deriving other ORDEM2010-required input populations for various components and types of debris. This paper describes the key elements and major steps in the statistical inference of the ORDEM2010 micro-debris populations. A crucial step is the construction of a degradation/ejecta source model to provide prior information on the micron-sized objects (such as orbital and object-size distributions). Another critical step is to link model populations with data, which is rather involved. It demands detailed information on area-time/directionality for all the space-exposed elements of a shuttle orbiter and damage laws, which relate impact damage with the physical properties of a projectile and impact conditions such as impact angle and velocity. Also needed are model-predicted debris fluxes as a function of object size and impact velocity from all possible directions. In spite of the very limited quantity of the available shuttle impact data, the population-derivation process is satisfactorily stable. Final modeling results obtained from shuttle window and radiator impact data are reasonably convergent and consistent, especially for the debris populations with object-size thresholds at 10 and 100 micron.

  11. Jason-2 systematic error analysis in the GPS derived orbits

    NASA Astrophysics Data System (ADS)

    Melachroinos, S.; Lemoine, F. G.; Zelensky, N. P.; Rowlands, D. D.; Luthcke, S. B.; Chinn, D. S.

    2011-12-01

    Several results related to global or regional sea level changes still too often rely on the assumption that orbit errors coming from station coordinates adoption can be neglected in the total error budget (Ceri et al. 2010). In particular Instantaneous crust-fixed coordinates are obtained by adding to the linear ITRF model the geophysical high-frequency variations. In principle, geocenter motion should also be included in this computation, in order to reference these coordinates to the center of mass of the whole Earth. This correction is currently not applied when computing GDR orbits. Cerri et al. (2010) performed an analysis of systematic errors common to all coordinates along the North/South direction, as this type of bias, also known as Z-shift, has a clear impact on MSL estimates due to the unequal distribution of continental surface in the northern and southern hemispheres. The goal of this paper is to specifically study the main source of errors which comes from the current imprecision in the Z-axis realization of the frame. We focus here on the time variability of this Z-shift, which we can decompose in a drift and a periodic component due to the presumably omitted geocenter motion. A series of Jason-2 GPS-only orbits have been computed at NASA GSFC, using both IGS05 and IGS08. These orbits have been shown to agree radially at less than 1 cm RMS vs our SLR/DORIS std0905 and std1007 reduced-dynamic orbits and in comparison with orbits produced by other analysis centers (Melachroinos et al. 2011). Our GPS-only JASON-2 orbit accuracy is assessed using a number of tests including analysis of independent SLR and altimeter crossover residuals, orbit overlap differences, and direct comparison to orbits generated at GSFC using SLR and DORIS tracking, and to orbits generated externally at other centers. Tests based on SLR-crossover residuals provide the best performance indicator for independent validation of the NASA/GSFC GPS-only reduced dynamic orbits. Reduced

  12. Orbiter CCTV video signal noise analysis

    NASA Technical Reports Server (NTRS)

    Lawton, R. M.; Blanke, L. R.; Pannett, R. F.

    1977-01-01

    The amount of steady state and transient noise which will couple to orbiter CCTV video signal wiring is predicted. The primary emphasis is on the interim system, however, some predictions are made concerning the operational system wiring in the cabin area. Noise sources considered are RF fields from on board transmitters, precipitation static, induced lightning currents, and induced noise from adjacent wiring. The most significant source is noise coupled to video circuits from associated circuits in common connectors. Video signal crosstalk is the primary cause of steady state interference, and mechanically switched control functions cause the largest induced transients.

  13. Economic analysis requirements in support of orbital debris regulatory policy

    NASA Astrophysics Data System (ADS)

    Greenberg, Joel S.

    1996-10-01

    As the number of Earth orbiting objects increases so does the potential for generating orbital debris with the consequent increase in the likelihood of impacting and damaging operating satellites. Various debris remediation approaches are being considered that encompass both in-orbit and return-to-Earth schema and have varying degrees of operations, cost, international competitiveness, and safety implications. Because of the diversity of issues, concerns and long-term impacts, there is a clear need for the setting of government policies that will lead to an orderly abatement of the potential orbital debris hazards. These policies may require the establishment of a supportive regulatory regime. The Department of Transportation is likely to have regulatory responsibilities relating to orbital debris stemming from its charge to protect the public health and safety, safety of property, and national security interests and foreign policy interests of the United States. This paper describes DOT's potential regulatory role relating to orbital debris remediation, the myriad of issues concerning the need for establishing government policies relating to orbital debris remediation and their regulatory implications, the proposed technological solutions and their economic and safety implications. Particular emphasis is placed upon addressing cost-effectiveness and economic analyses as they relate to economic impact analysis in support of regulatory impact analysis.

  14. On-orbit analysis of radiation shielding

    NASA Astrophysics Data System (ADS)

    Shavers, M. R.; Cucinotta, F. A.; Golightly, M. J.; Zapp, N.; Petrov, V.; Wilson, J. W.; Nealy, J. E.; Miller, J.; Zeitlin, C.; Heilbronn, L.

    Ground- and space-based experiments have validated the selection of polyethylene as an effective shield for radiation protection of humans from cosmic radiation exposure during spaceflight. Theoretical models that describe the physical interactions and transport of energetic ions through matter first identified the superior shielding performance of hydrogenous materials. Analytical transport models of space-like particle beams predicted that water would out-perform materials with higher effective charge, and plastics with low effective charge, particularly polyethylene (CH2), appeared to be even more promising. Experiments with accelerated particle beams confirmed the analytical predictions, and experimental measurements continue to provide validation of the use of polyethylene and other proposed shield materials for radiation protection during spaceflight. Due to the anisotropic radiation environment in low Earth orbit, vector flux models of incident radiation field and careful measurements on-orbit are required to definitively assess the effectiveness of polyethylene to protect the skin, eyes, and deeper tissues in that setting. An experiment is proposed herein in which operational and scientific detectors already aboard the ISS can be used to characterize the effectiveness of polyethylene as a radiation shield for reducing risks from geomagnetically trapped protons, cosmic ions, and albedo neutrons. Results are necessary for optimization of retrofit shield design, ab initio design of spacecraft, and development of analytical tools used in these activities and other operational aspects of radiation health and protection for human spaceflight.

  15. Orbital analysis for atmospheric trace molecule spectroscopy (ATMOS) Shuttle missions

    NASA Technical Reports Server (NTRS)

    Harrison, Edwin F.; Denn, Frederick M.; Gibson, Gary G.

    1988-01-01

    An orbital analysis was carried out to define the geographical coverage capabilities of an ATMOS solar occultation experiment on Space Shuttle/Spacelab missions. Particular attention was given to the effects of launch time, orbit inclination, altitude, and season on latitude-longitude coverage. It is shown that the widest band of latitude coverage in the tropics and temperate zones can be achieved with a midinclined orbit and a midmorning or late-night launch time. The use of ATMOS Shuttle underflights to provide coincident measurements with a solar occultation experiment on the Upper Atmospheric Research Satellite is also examined.

  16. Investigation of Orbital Debris: Mitigation, Removal, and Modeling the Debris Population

    NASA Astrophysics Data System (ADS)

    Slotten, Joel

    The population of objects in orbit around Earth has grown since the late 1950s. Today there are over 21,000 objects over 10 cm in length in orbit, and an estimated 500,000 more between 1 and 10 cm. Only a small fraction of these objects are operational satellites. The rest are debris: old derelict spacecraft or rocket bodies, fragments created as the result of explosions or collisions, discarded objects, slag from solid rockets, or even flaked off paint. Traveling at up to 7 km/s, a collision with even a 1 cm piece of debris could severely damage or destroy a satellite. This dissertation examines three aspects of orbital debris. First, the concept of a self-consuming satellite is explored. This nanosatellite would use its own external structure as propellant to execute a deorbit maneuver at the end of its operational life, thus allowing it to meet current debris mitigation standards. Results from lab experiments examining potential materials for this concept have shown favorable results. Second, Particle in Cell techniques are modified and used to model the plasma plume from a micro-cathode arc thruster. This model is then applied to the concept of an ion beam shepherd satellite. This satellite would use its plasma plume to deorbit another derelict satellite. Results from these simulations indicate the micro-cathode arc thruster could potentially deorbit a derelict CubeSat in a matter of a few weeks. Finally, the orbital debris population at geosynchronous orbit is examined, focusing on variations in the density of the population as a function of longitude. New insights are revealed demonstrating that the variation in population density is slightly less than previously reported.

  17. Independent Orbiter Assessment (IOA): Analysis of the Orbiter Experiment (OEX) subsystem

    NASA Technical Reports Server (NTRS)

    Compton, J. M.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Experiments hardware. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. The Orbiter Experiments (OEX) Program consists of a multiple set of experiments for the purpose of gathering environmental and aerodynamic data to develop more accurate ground models for Shuttle performance and to facilitate the design of future spacecraft. This assessment only addresses currently manifested experiments and their support systems. Specifically this list consists of: Shuttle Entry Air Data System (SEADS); Shuttle Upper Atmosphere Mass Spectrometer (SUMS); Forward Fuselage Support System for OEX (FFSSO); Shuttle Infrared Laced Temperature Sensor (SILTS); Aerodynamic Coefficient Identification Package (ACIP); and Support System for OEX (SSO). There are only two potential critical items for the OEX, since the experiments only gather data for analysis post mission and are totally independent systems except for power. Failure of any experiment component usually only causes a loss of experiment data and in no way jeopardizes the crew or mission.

  18. Independent Orbiter Assessment (IOA): Analysis of the orbiter main propulsion system

    NASA Technical Reports Server (NTRS)

    Mcnicoll, W. J.; Mcneely, M.; Holden, K. A.; Emmons, T. E.; Lowery, H. J.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Main Propulsion System (MPS) hardware are documented. The Orbiter MPS consists of two subsystems: the Propellant Management Subsystem (PMS) and the Helium Subsystem. The PMS is a system of manifolds, distribution lines and valves by which the liquid propellants pass from the External Tank (ET) to the Space Shuttle Main Engines (SSMEs) and gaseous propellants pass from the SSMEs to the ET. The Helium Subsystem consists of a series of helium supply tanks and their associated regulators, check valves, distribution lines, and control valves. The Helium Subsystem supplies helium that is used within the SSMEs for inflight purges and provides pressure for actuation of SSME valves during emergency pneumatic shutdowns. The balance of the helium is used to provide pressure to operate the pneumatically actuated valves within the PMS. Each component was evaluated and analyzed for possible failure modes and effects. Criticalities were assigned based on the worst possible effect of each failure mode. Of the 690 failure modes analyzed, 349 were determined to be PCIs.

  19. An Analysis of the Orbital Distribution of Solid Rocket Motor Slag

    NASA Technical Reports Server (NTRS)

    Horstman, Matthew F.; Mulrooney, Mark

    2007-01-01

    The contribution made by orbiting solid rocket motors (SRMs) to the orbital debris environment is both potentially significant and insufficiently studied. A combination of rocket motor design and the mechanisms of the combustion process can lead to the emission of sufficiently large and numerous by-products to warrant assessment of their contribution to the orbital debris environment. These particles are formed during SRM tail-off, or the termination of burn, by the rapid expansion, dissemination, and solidification of the molten Al2O3 slag pool accumulated during the main burn phase of SRMs utilizing immersion-type nozzles. Though the usage of SRMs is low compared to the usage of liquid fueled motors, the propensity of SRMs to generate particles in the 100 m and larger size regime has caused concern regarding their contributing to the debris environment. Particle sizes as large as 1 cm have been witnessed in ground tests conducted under vacuum conditions and comparable sizes have been estimated via ground-based telescopic and in-situ observations of sub-orbital SRM tail-off events. Using sub-orbital and post recovery observations, a simplistic number-size-velocity distribution of slag from on-orbit SRM firings was postulated. In this paper we have developed more elaborate distributions and emission scenarios and modeled the resultant orbital population and its time evolution by incorporating a historical database of SRM launches, propellant masses, and likely location and time of particulate deposition. From this analysis a more comprehensive understanding has been obtained of the role of SRM ejecta in the orbital debris environment, indicating that SRM slag is a significant component of the current and future population.

  20. Independent Orbiter Assessment (IOA): Weibull analysis report

    NASA Technical Reports Server (NTRS)

    Raffaelli, Gary G.

    1987-01-01

    The Auxiliary Power Unit (APU) and Hydraulic Power Unit (HPU) Space Shuttle Subsystems were reviewed as candidates for demonstrating the Weibull analysis methodology. Three hardware components were identified as analysis candidates: the turbine wheel, the gearbox, and the gas generator. Detailed review of subsystem level wearout and failure history revealed the lack of actual component failure data. In addition, component wearout data were not readily available or would require a separate data accumulation effort by the vendor. Without adequate component history data being available, the Weibull analysis methodology application to the APU and HPU subsystem group was terminated.

  1. Extensive Radiation Shielding Analysis for Different Spacecraft Orbits

    NASA Astrophysics Data System (ADS)

    Çay, Yiǧit; Kaymaz, Zerefsan

    2016-07-01

    Radiation environment around Earth poses a great danger for spacecraft and causes immature de-orbiting or loss of the spacecraft in near Earth space environment. In this study, a student project has been designed to build a CubeSat, PolarBeeSail (PBS), with an orbit having inclination of 80°, 4 Re in perigee and 20 Re in apogee to study the polar magnetospheric environment. An extensive radiation dose analyses were carried out for PBS orbit, and integral and differential fluxes were calculated using SPENVIS tools. A shielding analysis was performed and an optimum Aluminum thickness, 3 mm, was obtained. These results for PBS were then compared for other orbits at different altitudes both for polar and equatorial orbits. For this purpose, orbital characteristics of POES-19 and GOES-15 were used. The resulting proton flux analyses, TID analyses, and further shielding studies were conducted; comparisons and recommendations were made for future design of spacecraft that will use these environments.

  2. Numerical Analysis of Orbital Perturbation Effects on Inclined Geosynchronous SAR.

    PubMed

    Dong, Xichao; Hu, Cheng; Long, Teng; Li, Yuanhao

    2016-01-01

    The geosynchronous synthetic aperture radar (GEO SAR) is susceptible to orbit perturbations, leading to orbit drifts and variations. The influences behave very differently from those in low Earth orbit (LEO) SAR. In this paper, the impacts of perturbations on GEO SAR orbital elements are modelled based on the perturbed dynamic equations, and then, the focusing is analyzed theoretically and numerically by using the Systems Tool Kit (STK) software. The accurate GEO SAR slant range histories can be calculated according to the perturbed orbit positions in STK. The perturbed slant range errors are mainly the first and second derivatives, leading to image drifts and defocusing. Simulations of the point target imaging are performed to validate the aforementioned analysis. In the GEO SAR with an inclination of 53° and an argument of perigee of 90°, the Doppler parameters and the integration time are different and dependent on the geometry configurations. Thus, the influences are varying at different orbit positions: at the equator, the first-order phase errors should be mainly considered; at the perigee and apogee, the second-order phase errors should be mainly considered; at other positions, first-order and second-order exist simultaneously. PMID:27598168

  3. Independent Orbiter Assessment (IOA): Analysis of the auxiliary power unit

    NASA Technical Reports Server (NTRS)

    Barnes, J. E.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Auxiliary Power Unit (APU). The APUs are required to provide power to the Orbiter hydraulics systems during ascent and entry flight phases for aerosurface actuation, main engine gimballing, landing gear extension, and other vital functions. For analysis purposes, the APU system was broken down into ten functional subsystems. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. A preponderance of 1/1 criticality items were related to failures that allowed the hydrazine fuel to escape into the Orbiter aft compartment, creating a severe fire hazard, and failures that caused loss of the gas generator injector cooling system.

  4. Independent Orbiter Assessment (IOA): Analysis of the crew equipment subsystem

    NASA Technical Reports Server (NTRS)

    Sinclair, Susan; Graham, L.; Richard, Bill; Saxon, H.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical (PCIs) items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results coresponding to the Orbiter crew equipment hardware are documented. The IOA analysis process utilized available crew equipment hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 352 failure modes analyzed, 78 were determined to be PCIs.

  5. Independent Orbiter Assessment (IOA): Analysis of the pyrotechnics subsystem

    NASA Technical Reports Server (NTRS)

    Robinson, W. W.

    1988-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Pyrotechnics hardware. The IOA analysis process utilized available pyrotechnics hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  6. Probing the population of the spin-orbit split levels in the actinide 5f states

    SciTech Connect

    Moore, K; der Laan, G v; Tobin, J; Chung, B; Wall, M; Schwartz, A

    2004-07-14

    Spin-orbit interaction in the 5f states is believed to strongly influence exotic behaviors observed in actinides metals and compounds. Understanding these interactions and how they relate to the actinide series is of considerable importance. To address this issue, the branching ratio of the white-line peaks of the N4,5 edges for the light actinide metals, {alpha}-Th, {alpha}-U, and {alpha}-Pu were recorded using electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM) and synchrotron-radiation-based x-ray absorption spectroscopy (XAS). Using the spin-orbit sum rule and the branching ratios from both experimental spectra and many-electron atomic spectral calculations, accurate values of the spin-orbit interaction, and thus the relative occupation of the j = 5/2 and 7/2 levels, are determined for the actinide 5f states. Results show that the spin-orbit sum rule works very well with both EELS and XAS spectra, needing little or no correction. This is important, since the high spatial resolution of a TEM can be used to overcome the problems of single crystal growth often encountered with actinide metals, allowing acquisition of EELS spectra, and subsequent spin-orbit analysis, from nm-sized regions. The relative occupation numbers obtained by our method have been compared with recent theoretical results and show a good agreement in their trend.

  7. Analysis of differences between seating positions in simulators and orbiters

    NASA Technical Reports Server (NTRS)

    Mongan, Philip T.

    1993-01-01

    Crew comments indicate that Space Shuttle simulator seats place crewmembers in a position different from that of the actual Orbiter seats. The crew feel that they launch in a different position, and with a different reach and visibility, from that in which they had trained. This study examined three factors in differences between training and flight positions. Key dimensions, which were considered important to spatial orientation, were compared in the Orbiters and simulators. These were dimensions such as seat back to glare shield and seat pan to overhead. The differences between flight and training crew equipment, and how these differences may contribute to the problem were discussed with engineers and technicians responsible for the equipment. Eye position measurements were taken on subjects to assess any differences that could be attributed to different ingress methods in the Orbiters and the simulators. This report presents the data, analysis, and recommendations.

  8. Atmospheric gravitational influence on geodetic satellite orbits - Starlette analysis

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Chan, Joseph C.

    1992-01-01

    The atmosphere is constantly in motion. The changing gravitational force due to the air mass movement will slightly perturb the orbit of a satellite. As the instrument accuracy for geodetic satellites improves, failure to model this perturbation can result in significant systematic errors in the orbit determination. The latter, in turn, will degrade the Earth's gravity solutions. A direct modeling technique to analyze the atmospheric gravitational influence on geodetic satellite is developed. We use the global surface pressure data from the ECMWF Initial Analysis Database to compute the gravitational force due to atmospheric perturbation exerted on given satellite as a function of time during selected orbital arcs. Satellite Laser Ranging (SLR) tracking data for selected Starlette (altitude 900 km) orbital arcs are used to test the computed force model. Although only a slight reduction in the rms residuals is observed when the atmospheric gravitational perturbation is included in the force model for data reduction of the SLR data, significant improvement is obtained in the predictability of the satellite orbit. Comprehensive studies involving more definitive test criteria and more refined models are still needed.

  9. Analysis on high-altitude earth Orbit Satellite Determination

    NASA Astrophysics Data System (ADS)

    He, J.; Hou, Y. W.; Yang, L.

    2016-02-01

    The difference is introduced between approx circular apogee orbit and approx circular perigee one by error transmitting at first. Then the characteristic of secant compensation is analysed when radar tracking object with high elevation. And two kinds of orbit force be pressed to, their perturbation influence and their earth-core angles are explained. And then the series of emulation results are shown including error data emulated with Monte Carlo method, the influence of the velocity increment from the ejecting force of spring while satellite-rocket separating and their perturbation influence and the length of influence of the data arc. Then decision analysis of Wald method and Bayesian statistics rule and the results from the two rule are introduced. So the suitable orbit determination decision is put forward from the decision method. Finally the result is tested reasonable and feasible via the real data. In the end it is useful to reference to make orbit decision in short injection of circular orbit far from the earth for calculating concurrently precise and timely.

  10. Solar Thermal : Solar Electric Propulsion Hybrid Orbit Transfer Analysis

    NASA Astrophysics Data System (ADS)

    McFall, Keith A.

    2000-07-01

    This effort examined the payoffs associated with the joint application of solar thermal propulsion (STP) and electric propulsion (EP) for orbit raising. The combined use of STP (800 second specific impulse) and EP (1800 second specific impulse) for a single orbit transfer mission is motivated by the desire to leverage the higher thrust of STP with the higher specific impulse of EP to maximize mission capability. The primary objectives of this analysis were to quantify the payload, mission duration, and hydrogen propellant to payload mass ratio for a range of combined STP and EP orbit transfer missions to geosynchronous Earth orbit (GEO), and contrast them to results for STP only. For STP, the hydrogen propellant to payload mass ratio is of particular interest due to payload fairing size constraints and the relatively low density of liquid hydrogen, which limit the mass of the STP propellant, and therefore the amount of payload that can be delivered. The results of the analysis include an 18% payload improvement associated with STP-EP hybrid propulsion over STP alone. The trip time needed for the STP-EP transfer varied from 101 to 143 days, compared to 41 days for the Solar only case. In addition, the amount of hydrogen propellant needed to accomplish the orbit raising to GEO per unit mass of payload decreased by 29% when the Solar Thermal - Solar Electric hybrid was used. While comprehensive comparisons of STP-EP to chemical propulsion (CP) only and to CP with EP orbit topping were also of interest, they were beyond the scope of this effort. However, a comparison of reference missions was performed. In comparison to the reference CP (328 second specific impulse) and CP-EP missions the STP-EP system provided 67% and 39% payload increases. respectively. The trip time for the CP-EP cases varied from 55 to 106 days.

  11. Automated Orbit Determination System (AODS) requirements definition and analysis

    NASA Technical Reports Server (NTRS)

    Waligora, S. R.; Goorevich, C. E.; Teles, J.; Pajerski, R. S.

    1980-01-01

    The requirements definition for the prototype version of the automated orbit determination system (AODS) is presented including the AODS requirements at all levels, the functional model as determined through the structured analysis performed during requirements definition, and the results of the requirements analysis. Also specified are the implementation strategy for AODS and the AODS-required external support software system (ADEPT), input and output message formats, and procedures for modifying the requirements.

  12. SWSextantis stars: the dominant population of cataclysmic variables with orbital periods between 3 and 4h

    NASA Astrophysics Data System (ADS)

    Rodríguez-Gil, P.; Gänsicke, B. T.; Hagen, H.-J.; Araujo-Betancor, S.; Aungwerojwit, A.; Allende Prieto, C.; Boyd, D.; Casares, J.; Engels, D.; Giannakis, O.; Harlaftis, E. T.; Kube, J.; Lehto, H.; Martínez-Pais, I. G.; Schwarz, R.; Skidmore, W.; Staude, A.; Torres, M. A. P.

    2007-06-01

    We present time-series optical photometry of five new cataclysmic variables (CVs) identified by the Hamburg Quasar Survey (HQS). The deep eclipses observed in HS 0129+2933 (= TT Tri), HS 0220+0603 and HS 0455+8315 provided very accurate orbital periods of 3.35129827(65), 3.58098501(34) and 3.56937674(26) h, respectively. HS 0805+3822 shows grazing eclipses and has a likely orbital period of 3.2169(2) h. Time-resolved optical spectroscopy of the new CVs (with the exception of HS 0805+3822) is also presented. Radial velocity studies of the Balmer emission lines provided an orbital period of 3.55 h for HS 1813+6122, which allowed us to identify the observed photometric signal at 3.39 h as a negative superhump wave. The spectroscopic behaviour exhibited by all the systems clearly identifies them as new SW Sextantis (SW Sex) stars. HS 0220+0603 shows unusual NII and SiII emission lines suggesting that the donor star may have experienced nuclear evolution via the CNO cycle. These five new additions to the class increase the number of known SW Sex stars to 35. Almost 40 per cent of the total SW Sex population do not show eclipses, invalidating the requirement of eclipses as a defining characteristic of the class and the models based on a high orbital inclination geometry alone. On the other hand, as more SW Sex stars are identified, the predominance of orbital periods in the narrow 3-4.5 h range is becoming more pronounced. In fact, almost half the CVs which populate the 3-4.5 h period interval are definite members of the class. The dominance of SW Sex stars is even stronger in the 2-3 h period gap, where they make up 55 per cent of all known gap CVs. These statistics are confirmed by our results from the HQS CVs. Remarkably, 54 per cent of the Hamburg nova-like variables have been identified as SW Sex stars with orbital periods in the 3-4.5 h range. The observation of this pile-up of systems close to the upper boundary of the period gap is difficult to reconcile with the

  13. A consistent orbital stability analysis for the GJ 581 system

    SciTech Connect

    Joiner, David A.; Sul, Cesar; Kress, Monika E.; Dragomir, Diana; Kane, Stephen R.

    2014-06-20

    We apply a combination of N-body modeling techniques and automated data fitting with Monte Carlo Markov Chain uncertainty analysis of Keplerian orbital models to RV data to determine long-term stability of the planetary system GJ 581. We find that while there are stability concerns with the four-planet model as published by Forveille et al., when uncertainties in the system are accounted for, particularly stellar jitter, the hypothesis that the four-planet model is gravitationally unstable is not statistically significant. Additionally, the system including proposed planet g by Vogt et al. also shows some stability concerns when eccentricities are allowed to float in the orbital fit, yet when uncertainties are included in the analysis, the system including planet g also cannot be proven to be unstable. We present revised reduced χ{sup 2} values for Keplerian astrocentric orbital fits assuming four-planet and five-planet models for GJ 581 under the condition that best fits must be stable, and we find no distinguishable difference by including planet g in the model. Additionally, we present revised orbital element estimates for each, assuming uncertainties due to stellar jitter under the constraint of the system being gravitationally stable.

  14. Independent Orbiter Assessment (IOA): Analysis of the body flap subsystem

    NASA Technical Reports Server (NTRS)

    Wilson, R. E.; Riccio, J. R.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Body Flap (BF) subsystem hardware are documented. The BF is a large aerosurface located at the trailing edge of the lower aft fuselage of the Orbiter. The proper function of the BF is essential during the dynamic flight phases of ascent and entry. During the ascent phase of flight, the BF trails in a fixed position. For entry, the BF provides elevon load relief, trim control, and acts as a heat shield for the main engines. Specifically, the BF hardware comprises the following components: Power Drive Unit (PDU), rotary actuators, and torque tubes. The IOA analysis process utilized available BF hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 35 failure modes analyzed, 19 were determined to be PCIs.

  15. To Preserve or Not to Preserve the Orbit in Paranasal Sinus Neoplasms: A Meta-Analysis

    PubMed Central

    Reyes, Camilo; Mason, Eric; Solares, C. Arturo; Bush, Carrie; Carrau, Ricardo

    2014-01-01

    Context The effect on survival of orbital evisceration on patients with paranasal sinus neoplasms has not been well established. Objective To review systematically the available literature concerning survival in patients who undergo surgery for paranasal sinus neoplasm with and without preservation of the eye. Data Source A retrospective meta-analysis of English and non-English articles using Medline and the Cochrane database. Eligibility Criteria Studies analyzing 5-year survival rates in patients who had orbital evisceration compared with orbital preservation for the treatment of paranasal sinus neoplasms were included in the final analysis. Data Extraction Independent review by two authors using predefined data fields. Data Synthesis A meta-analysis of four articles involving 443 patients was performed using the DerSimonian-Laird random-effects method. Results Our analysis revealed a total effect size of 0.964 in favor of preservation of the eye; however, these results are not robust, having a true effect size anywhere from 0.785 to 1.142 with a 95% confidence interval. Limitations Only retrospective observational studies were included because a prospective randomized study cannot be performed in this population. Conclusion Our study supports the notion that in select patients preservation of the eye may yield a different outcome when compared with orbital evisceration. PMID:25844298

  16. In-Orbit Collision Analysis for VEGA Second Flight

    NASA Astrophysics Data System (ADS)

    Volpi, M.; Fossati, T.; Battie, F.

    2013-08-01

    ELV, as prime contractor of the VEGA launcher, which operates in the protected LEO zone (up to 2000 km altitude), has to demonstrate that it abides by ESA debris mitigation rules, as well as by those imposed by the French Law on Space Operations (LOS). After the full success of VEGA qualification flight, the second flight(VV02) will extend the qualification domain of the launcher to multi-payload missions, with the release of two satellites (Proba-V and VNRedSat-1) and one Cubesat (ESTCube-1) on different SSO orbits The multi-payload adapter, VESPA, also separates its upper part before the second payload release. This paper will present the results of the long-term analyses on inorbit collision between these different bodies. Typical duration of propagation requested by ELV customer is around 50 orbits, requiring a state-of-the-art simulator able to compute efficiently orbits disturbs, usually neglected in launcher trajectory optimization itself. To address the issue of in-orbit collision, ELV has therefore developed its own simulator, POLPO [1], a FORTRAN code which performs the long-term propagation of the released objects trajectories and computes the mutual distance between them. The first part of the paper shall introduce the simulator itself, explaining the computation method chosen and briefly discussing the perturbing effects and their models taken into account in the tool, namely: - gravity field modeling (zonal and tesseral harmonics) - atmospheric model - solar pressure - third-body interaction A second part will describe the application of the in-orbit collision analysis to the second flight mission. Main characteristics of the second flight will be introduced, as well as the dispersions considered for the Monte-Carlo analysis performed. The results of the long-term collision analysis between all the separated bodies will then be presented and discussed.

  17. Global stability of periodic orbits of non-autonomous difference equations and population biology

    NASA Astrophysics Data System (ADS)

    Elaydi, Saber; Sacker, Robert J.

    Elaydi and Yakubu showed that a globally asymptotically stable(GAS) periodic orbit in an autonomous difference equation must in fact be a fixed point whenever the phase space is connected. In this paper we extend this result to periodic nonautonomous difference equations via the concept of skew-product dynamical systems. We show that for a k-periodic difference equation, if a periodic orbit of period r is GAS, then r must be a divisor of k. In particular sub-harmonic, or long periodic, oscillations cannot occur. Moreover, if r divides k we construct a non-autonomous dynamical system having minimum period k and which has a GAS periodic orbit with minimum period r. Our methods are then applied to prove a conjecture by J. Cushing and S. Henson concerning a non-autonomous Beverton-Holt equation which arises in the study of the response of a population to a periodically fluctuating environmental force such as seasonal fluctuations in carrying capacity or demographic parameters like birth or death rates.

  18. Independent Orbiter Assessment (IOA): Analysis of the DPS subsystem

    NASA Technical Reports Server (NTRS)

    Lowery, H. J.; Haufler, W. A.; Pietz, K. C.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) is presented. The IOA approach features a top-down analysis of the hardware to independently determine failure modes, criticality, and potential critical items. The independent analysis results corresponding to the Orbiter Data Processing System (DPS) hardware are documented. The DPS hardware is required for performing critical functions of data acquisition, data manipulation, data display, and data transfer throughout the Orbiter. Specifically, the DPS hardware consists of the following components: Multiplexer/Demultiplexer (MDM); General Purpose Computer (GPC); Multifunction CRT Display System (MCDS); Data Buses and Data Bus Couplers (DBC); Data Bus Isolation Amplifiers (DBIA); Mass Memory Unit (MMU); and Engine Interface Unit (EIU). The IOA analysis process utilized available DPS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Due to the extensive redundancy built into the DPS the number of critical items are few. Those identified resulted from premature operation and erroneous output of the GPCs.

  19. Independent Orbiter Assessment (IOA): Analysis of the extravehicular mobility unit

    NASA Technical Reports Server (NTRS)

    Raffaelli, Gary G.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Extravehicular Mobility Unit (EMU) hardware. The EMU is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for the Shuttle crewmember to perform Extravehicular Activity (EVA) in Earth orbit. Two EMUs are included on each baseline Orbiter mission, and consumables are provided for three two-man EVAs. The EMU consists of the Life Support System (LSS), Caution and Warning System (CWS), and the Space Suit Assembly (SSA). Each level of hardware was evaluated and analyzed for possible failure modes and effects. The majority of these PCIs are resultant from failures which cause loss of one or more primary functions: pressurization, oxygen delivery, environmental maintenance, and thermal maintenance. It should also be noted that the quantity of PCIs would significantly increase if the SOP were to be treated as an emergency system rather than as an unlike redundant element.

  20. Nonlinear dynamical analysis for displaced orbits above a planet

    NASA Astrophysics Data System (ADS)

    Xu, Ming; Xu, Shijie

    2008-12-01

    Nonlinear dynamical analysis and the control problem for a displaced orbit above a planet are discussed. It is indicated that there are two equilibria for the system, one hyperbolic (saddle) and one elliptic (center), except for the degenerate h {/z max}, a saddle-node bifurcation point. Motions near the equilibria for the nonresonance case are investigated by means of the Birkhoff normal form and dynamical system techniques. The Kolmogorov Arnold Moser (KAM) torus filled with quasiperiodic trajectories is measured in the τ 1 and τ 2 directions, and a rough algorithm for calculating τ 1 and τ 2 is proposed. A general iterative algorithm to generate periodic Lyapunov orbits is also presented. Transitions in the neck region are demonstrated, respectively, in the nonresonance, resonance, and degradation cases. One of the important contributions of the paper is to derive necessary and sufficiency conditions for stability of the motion near the equilibria. Another contribution is to demonstrate numerically that the critical KAM torus of nontransition is filled with the (1,1)-homoclinic orbits of the Lyapunov orbit.

  1. Magnetospheric Multiscale (MMS) Mission Commissioning Phase Orbit Determination Error Analysis

    NASA Technical Reports Server (NTRS)

    Chung, Lauren R.; Novak, Stefan; Long, Anne; Gramling, Cheryl

    2009-01-01

    The Magnetospheric MultiScale (MMS) mission commissioning phase starts in a 185 km altitude x 12 Earth radii (RE) injection orbit and lasts until the Phase 1 mission orbits and orientation to the Earth-Sun li ne are achieved. During a limited time period in the early part of co mmissioning, five maneuvers are performed to raise the perigee radius to 1.2 R E, with a maneuver every other apogee. The current baseline is for the Goddard Space Flight Center Flight Dynamics Facility to p rovide MMS orbit determination support during the early commissioning phase using all available two-way range and Doppler tracking from bo th the Deep Space Network and Space Network. This paper summarizes th e results from a linear covariance analysis to determine the type and amount of tracking data required to accurately estimate the spacecraf t state, plan each perigee raising maneuver, and support thruster cal ibration during this phase. The primary focus of this study is the na vigation accuracy required to plan the first and the final perigee ra ising maneuvers. Absolute and relative position and velocity error hi stories are generated for all cases and summarized in terms of the ma ximum root-sum-square consider and measurement noise error contributi ons over the definitive and predictive arcs and at discrete times inc luding the maneuver planning and execution times. Details of the meth odology, orbital characteristics, maneuver timeline, error models, and error sensitivities are provided.

  2. Structural Health Monitoring Analysis for the Orbiter Wing Leading Edge

    NASA Technical Reports Server (NTRS)

    Yap, Keng C.

    2010-01-01

    This viewgraph presentation reviews Structural Health Monitoring Analysis for the Orbiter Wing Leading Edge. The Wing Leading Edge Impact Detection System (WLE IDS) and the Impact Analysis Process are also described to monitor WLE debris threats. The contents include: 1) Risk Management via SHM; 2) Hardware Overview; 3) Instrumentation; 4) Sensor Configuration; 5) Debris Hazard Monitoring; 6) Ascent Response Summary; 7) Response Signal; 8) Distribution of Flight Indications; 9) Probabilistic Risk Analysis (PRA); 10) Model Correlation; 11) Impact Tests; 12) Wing Leading Edge Modeling; 13) Ascent Debris PRA Results; and 14) MM/OD PRA Results.

  3. Independent Orbiter Assessment (IOA): Analysis of the instrumentation subsystem

    NASA Technical Reports Server (NTRS)

    Howard, B. S.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Instrumentation Subsystem are documented. The Instrumentation Subsystem (SS) consists of transducers, signal conditioning equipment, pulse code modulation (PCM) encoding equipment, tape recorders, frequency division multiplexers, and timing equipment. For this analysis, the SS is broken into two major groupings: Operational Instrumentation (OI) equipment and Modular Auxiliary Data System (MADS) equipment. The OI equipment is required to acquire, condition, scale, digitize, interleave/multiplex, format, and distribute operational Orbiter and payload data and voice for display, recording, telemetry, and checkout. It also must provide accurate timing for time critical functions for crew and payload specialist use. The MADS provides additional instrumentation to measure and record selected pressure, temperature, strain, vibration, and event data for post-flight playback and analysis. MADS data is used to assess vehicle responses to the flight environment and to permit correlation of such data from flight to flight. The IOA analysis utilized available SS hardware drawings and schematics for identifying hardware assemblies and components and their interfaces. Criticality for each item was assigned on the basis of the worst-case effect of the failure modes identified.

  4. Mission analysis data for inclined geosynchronous orbits, part 1

    NASA Technical Reports Server (NTRS)

    Graf, O. F., Jr.; Wang, K. C.

    1980-01-01

    Data needed for preliminary design of inclined geosynchronous missions are provided. The inertial and Earth fixed coordinate systems are described, as well as orbit parameters and elements. The complete family of geosynchronous orbits is discussed. It is shown that circular inclined geosynchronous orbits comprise only one set in this family. The major orbit perturbation and their separate effects on the geosynchronous orbit are discussed. Detailed information on the orbit perturbation of inclined circular geosynchronous orbits is given, with emphasis on time history data of certain orbital elements. Orbit maintenance delta velocity (V) requirements to counteract the major orbit perturbations are determined in order to provide order of magnitude estimates and to show the effects of orbit inclination on delta V. Some of the considerations in mission design for a multisatellite system, such as a halo orbit constellation, are discussed.

  5. Analysis of Errors in a Special Perturbations Satellite Orbit Propagator

    SciTech Connect

    Beckerman, M.; Jones, J.P.

    1999-02-01

    We performed an analysis of error densities for the Special Perturbations orbit propagator using data for 29 satellites in orbits of interest to Space Shuttle and International Space Station collision avoidance. We find that the along-track errors predominate. These errors increase monotonically over each 36-hour prediction interval. The predicted positions in the along-track direction progressively either leap ahead of or lag behind the actual positions. Unlike the along-track errors the radial and cross-track errors oscillate about their nearly zero mean values. As the number of observations per fit interval decline the along-track prediction errors, and amplitudes of the radial and cross-track errors, increase.

  6. Independent Orbiter Assessment (IOA): Analysis of the backup flight system

    NASA Technical Reports Server (NTRS)

    Prust, E. E.; Mielke, R. W.; Hinsdale, L. W.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the analysis results corresponding to the Orbiter Backup Flight System (BFS) hardware. The BFS hardware consists of one General Purpose Computer (GPC) loaded with backup flight software and the components used to engage/disengage that unique GPC. Specifically, the BFS hardware includes the following: DDU (Display Driver Unit), BFC (Backup Flight Controller), GPC (General Purpose Computer), switches (engage, disengage, GPC, CRT), and circuit protectors (fuses, circuit breakers). The IOA analysis process utilized available BFS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the failure modes analyzed, 19 could potentially result in a loss of life and/or loss of vehicle.

  7. Independent Orbiter Assessment (IOA): Analysis of the mechanical actuation subsystem

    NASA Technical Reports Server (NTRS)

    Bacher, J. L.; Montgomery, A. D.; Bradway, M. W.; Slaughter, W. T.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Mechanical Actuation System (MAS) hardware. Specifically, the MAS hardware consists of the following components: Air Data Probe (ADP); Elevon Seal Panel (ESP); External Tank Umbilical (ETU); Ku-Band Deploy (KBD); Payload Bay Doors (PBD); Payload Bay Radiators (PBR); Personnel Hatches (PH); Vent Door Mechanism (VDM); and Startracker Door Mechanism (SDM). The IOA analysis process utilized available MAS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  8. Independent Orbiter Assessment (IOA): Analysis of the remote manipulator system

    NASA Technical Reports Server (NTRS)

    Tangorra, F.; Grasmeder, R. F.; Montgomery, A. D.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Remote Manipulator System (RMS) are documented. The RMS hardware and software are primarily required for deploying and/or retrieving up to five payloads during a single mission, capture and retrieve free-flying payloads, and for performing Manipulator Foot Restraint operations. Specifically, the RMS hardware consists of the following components: end effector; displays and controls; manipulator controller interface unit; arm based electronics; and the arm. The IOA analysis process utilized available RMS hardware drawings, schematics and documents for defining hardware assemblies, components and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 574 failure modes analyzed, 413 were determined to be PCIs.

  9. ORAN- ORBITAL AND GEODETIC PARAMETER ESTIMATION ERROR ANALYSIS

    NASA Technical Reports Server (NTRS)

    Putney, B.

    1994-01-01

    The Orbital and Geodetic Parameter Estimation Error Analysis program, ORAN, was developed as a Bayesian least squares simulation program for orbital trajectories. ORAN does not process data, but is intended to compute the accuracy of the results of a data reduction, if measurements of a given accuracy are available and are processed by a minimum variance data reduction program. Actual data may be used to provide the time when a given measurement was available and the estimated noise on that measurement. ORAN is designed to consider a data reduction process in which a number of satellite data periods are reduced simultaneously. If there is more than one satellite in a data period, satellite-to-satellite tracking may be analyzed. The least squares estimator in most orbital determination programs assumes that measurements can be modeled by a nonlinear regression equation containing a function of parameters to be estimated and parameters which are assumed to be constant. The partitioning of parameters into those to be estimated (adjusted) and those assumed to be known (unadjusted) is somewhat arbitrary. For any particular problem, the data will be insufficient to adjust all parameters subject to uncertainty, and some reasonable subset of these parameters is selected for estimation. The final errors in the adjusted parameters may be decomposed into a component due to measurement noise and a component due to errors in the assumed values of the unadjusted parameters. Error statistics associated with the first component are generally evaluated in an orbital determination program. ORAN is used to simulate the orbital determination processing and to compute error statistics associated with the second component. Satellite observations may be simulated with desired noise levels given in many forms including range and range rate, altimeter height, right ascension and declination, direction cosines, X and Y angles, azimuth and elevation, and satellite-to-satellite range and

  10. Independent Orbiter Assessment (IOA): Analysis of the elevon subsystem

    NASA Technical Reports Server (NTRS)

    Wilson, R. E.; Riccio, J. R.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results for the Orbiter Elevon system hardware. The elevon actuators are located at the trailing edge of the wing surface. The proper function of the elevons is essential during the dynamic flight phases of ascent and entry. In the ascent phase of flight, the elevons are used for relieving high wing loads. For entry, the elevons are used to pitch and roll the vehicle. Specifically, the elevon system hardware comprises the following components: flow cutoff valve; switching valve; electro-hydraulic (EH) servoactuator; secondary delta pressure transducer; bypass valve; power valve; power valve check valve; primary actuator; primary delta pressure transducer; and primary actuator position transducer. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 25 failure modes analyzed, 18 were determined to be PCIs.

  11. New osculating orbits for 110 comets and analysis of original orbits for 200 comets

    NASA Technical Reports Server (NTRS)

    Marsden, B. G.; Sekanina, Z.; Everhart, E.

    1978-01-01

    Osculating orbits are presented for 110 nearly parabolic comets. Combining these with selected orbit determinations from other sources, a total of 200 orbits are considered where the available observations yield a result of very good (first-class) or good (second-class) quality. For each of these, the original and future orbits (referred to the barycenter of the solar system) are calculated. The Oort effect (a tendency for original reciprocal semimajor axis values to range from zero to +100 millionths per AU) is clearly seen among the first-class orbits but not among the second-class orbits. Modifications in original reciprocal semimajor axis values due to the effects of nongravitational forces are considered.

  12. Orbiter Repair Maneuver Contingency Separation Methods and Analysis

    NASA Technical Reports Server (NTRS)

    Machula, Michael

    2005-01-01

    Repairing damaged thermal protection system tile requires the Space Shuttle to be oriented such that repair platform access from the International Space Station (ISS) is possible. To do this, the Space Shuttle uses the Orbiter Repair Maneuver (ORM), which utilizes the Shuttle Remote Manipulator System (SRMS) to rotate the Space Shuttle in relation to the ISS, for extended periods of time. These positions cause difficulties and challenges to performing a safe separation (no collision or thruster plume damage to sensitive ISS structures) should an inadvertent release occur or a contingency procedure require it. To help protect for an SRMS failure or other failures, a method for separating without collision and the ability to redock to ISS from the ORM configuration was needed. The contingency ORM separation solution elegantly takes advantage of orbital mechanics between ISS and the separating Space Shuttle. By pitching the ISS down approximately 45 degrees, in a majority of the ORM repair positions, the altitude difference between the ISS and Space Shuttle center of gravity is maximized. This altitude difference results in different orbital energies (orbital periods) causing objects to separate from each other without requiring translational firings. Using this method, a safe contingency ORM separation is made possible in many odd positions even though some separation positions point high powered thrusters directly at fragile ISS and Soyuz solar arrays. Documented in this paper are the development simulations and procedures of the contingency ORM separation and the challenges encountered with large constraints to work around. Lastly, a method of returning to redock with the ISS to pick up the stranded crew members (or transfer the final crew members) is explained as well as the thruster and ISS loads analysis.

  13. Orbit determination covariance analysis for the Deep Space Program Science Experiment mission

    NASA Technical Reports Server (NTRS)

    Beckman, M.; Yee, C.; Lee, T.; Hoppe, M.; Oza, D.

    1993-01-01

    To define an appropriate orbit support procedure for the DSPSE mission, detailed permission orbit determination covariance analyses have been performed for the translunar and trans-Geographos mission phases. Preliminary analyses were also performed for the lunar mapping mission phase. These analyses are designed to assess the tracking patterns and the amount of tracking data needed to obtain orbit solutions of required accuracy for each mission phase and before and after each major orbit perturbation, such as orbit maneuvers and flybys of the Earth and Moon. In addition to operational orbit determination procedures, these analyses identify major error sources, estimate their contribution to orbital errors, and address possible strategies to reduce orbit determination error. For the lunar orbit phase, several lunar gravity error modeling approaches have been investigated. The covariance analysis results presented in this paper will serve as a guide for providing orbit determination support for the DSPSE mission.

  14. Molecular orbital analysis of the hydrogen bonded water dimer

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Jiang, Wanrun; Dai, Xin; Gao, Yang; Wang, Zhigang; Zhang, Rui-Qin

    2016-02-01

    As an essential interaction in nature, hydrogen bonding plays a crucial role in many material formations and biological processes, requiring deeper understanding. Here, using density functional theory and post-Hartree-Fock methods, we reveal two hydrogen bonding molecular orbitals crossing the hydrogen-bond’s O and H atoms in the water dimer. Energy decomposition analysis also shows a non-negligible contribution of the induction term. Our finding sheds light on the essential understanding of hydrogen bonding in ice, liquid water, functional materials and biological systems.

  15. Molecular orbital analysis of the hydrogen bonded water dimer

    PubMed Central

    Wang, Bo; Jiang, Wanrun; Dai, Xin; Gao, Yang; Wang, Zhigang; Zhang, Rui-Qin

    2016-01-01

    As an essential interaction in nature, hydrogen bonding plays a crucial role in many material formations and biological processes, requiring deeper understanding. Here, using density functional theory and post-Hartree-Fock methods, we reveal two hydrogen bonding molecular orbitals crossing the hydrogen-bond’s O and H atoms in the water dimer. Energy decomposition analysis also shows a non-negligible contribution of the induction term. Our finding sheds light on the essential understanding of hydrogen bonding in ice, liquid water, functional materials and biological systems. PMID:26905305

  16. Analysis of Satellite and Sub-Orbital Measurements

    NASA Technical Reports Server (NTRS)

    Gleason, James (Technical Monitor); Martin, Randall V.

    2004-01-01

    The objective of this project is to support the INTEX aircraft mission by developing experience in the integrated analysis of existing sub-orbital observations and satellite observations with numerical models. Specific tasks include providing guidance to INTEX by identifying discrepancies in satellite observations with (1) in situ measurements, (2) bottom-up emission inventories of nitrogen oxides and volatile organic compounds, and (3) model calculations of the export of pollution from North America to the global atmosphere. An important focus area is developing and improving bottom-up emission inventories by combining top-down and bottom-up information.

  17. SPICE Module for the Satellite Orbit Analysis Program (SOAP)

    NASA Technical Reports Server (NTRS)

    Coggi, John; Carnright, Robert; Hildebrand, Claude

    2008-01-01

    A SPICE module for the Satellite Orbit Analysis Program (SOAP) precisely represents complex motion and maneuvers in an interactive, 3D animated environment with support for user-defined quantitative outputs. (SPICE stands for Spacecraft, Planet, Instrument, Camera-matrix, and Events). This module enables the SOAP software to exploit NASA mission ephemeris represented in the JPL Ancillary Information Facility (NAIF) SPICE formats. Ephemeris types supported include position, velocity, and orientation for spacecraft and planetary bodies including the Sun, planets, natural satellites, comets, and asteroids. Entire missions can now be imported into SOAP for 3D visualization, playback, and analysis. The SOAP analysis and display features can now leverage detailed mission files to offer the analyst both a numerically correct and aesthetically pleasing combination of results that can be varied to study many hypothetical scenarios. The software provides a modeling and simulation environment that can encompass a broad variety of problems using orbital prediction. For example, ground coverage analysis, communications analysis, power and thermal analysis, and 3D visualization that provide the user with insight into complex geometric relations are included. The SOAP SPICE module allows distributed science and engineering teams to share common mission models of known pedigree, which greatly reduces duplication of effort and the potential for error. The use of the software spans all phases of the space system lifecycle, from the study of future concepts to operations and anomaly analysis. It allows SOAP software to correctly position and orient all of the principal bodies of the Solar System within a single simulation session along with multiple spacecraft trajectories and the orientation of mission payloads. In addition to the 3D visualization, the user can define numeric variables and x-y plots to quantitatively assess metrics of interest.

  18. Filter parameter tuning analysis for operational orbit determination support

    NASA Technical Reports Server (NTRS)

    Dunham, J.; Cox, C.; Niklewski, D.; Mistretta, G.; Hart, R.

    1994-01-01

    The use of an extended Kalman filter (EKF) for operational orbit determination support is being considered by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD). To support that investigation, analysis was performed to determine how an EKF can be tuned for operational support of a set of earth-orbiting spacecraft. The objectives of this analysis were to design and test a general purpose scheme for filter tuning, evaluate the solution accuracies, and develop practical methods to test the consistency of the EKF solutions in an operational environment. The filter was found to be easily tuned to produce estimates that were consistent, agreed with results from batch estimation, and compared well among the common parameters estimated for several spacecraft. The analysis indicates that there is not a sharply defined 'best' tunable parameter set, especially when considering only the position estimates over the data arc. The comparison of the EKF estimates for the user spacecraft showed that the filter is capable of high-accuracy results and can easily meet the current accuracy requirements for the spacecraft included in the investigation. The conclusion is that the EKF is a viable option for FDD operational support.

  19. Orbit Response Matrix Analysis Applied at PEP-II

    SciTech Connect

    Steier, C.; Wolski, A.; Ecklund, S.; Safranek, J.A.; Tenenbaum, P.; Terebilo, A.; Turner, J.L.; Yocky, G.; /SLAC

    2005-05-17

    The analysis of orbit response matrices has been used very successfully to measure and correct the gradient and skew gradient distribution in many accelerators. It allows determination of an accurately calibrated model of the coupled machine lattice, which then can be used to calculate the corrections necessary to improve coupling, dynamic aperture and ultimately luminosity. At PEP-II, the Matlab version of LOCO has been used to analyze coupled response matrices for both the LER and the HER. The large number of elements in PEP-II and the very complicated interaction region present unique challenges to the data analysis. All necessary tools to make the analysis method useable at PEP-II have been implemented and LOCO can now be used as a routine tool for lattice diagnostic.

  20. Analysis of filter tuning techniques for sequential orbit determination

    NASA Technical Reports Server (NTRS)

    Lee, T.; Yee, C.; Oza, D.

    1995-01-01

    This paper examines filter tuning techniques for a sequential orbit determination (OD) covariance analysis. Recently, there has been a renewed interest in sequential OD, primarily due to the successful flight qualification of the Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) using Doppler data extracted onboard the Extreme Ultraviolet Explorer (EUVE) spacecraft. TONS computes highly accurate orbit solutions onboard the spacecraft in realtime using a sequential filter. As the result of the successful TONS-EUVE flight qualification experiment, the Earth Observing System (EOS) AM-1 Project has selected TONS as the prime navigation system. In addition, sequential OD methods can be used successfully for ground OD. Whether data are processed onboard or on the ground, a sequential OD procedure is generally favored over a batch technique when a realtime automated OD system is desired. Recently, OD covariance analyses were performed for the TONS-EUVE and TONS-EOS missions using the sequential processing options of the Orbit Determination Error Analysis System (ODEAS). ODEAS is the primary covariance analysis system used by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD). The results of these analyses revealed a high sensitivity of the OD solutions to the state process noise filter tuning parameters. The covariance analysis results show that the state estimate error contributions from measurement-related error sources, especially those due to the random noise and satellite-to-satellite ionospheric refraction correction errors, increase rapidly as the state process noise increases. These results prompted an in-depth investigation of the role of the filter tuning parameters in sequential OD covariance analysis. This paper analyzes how the spacecraft state estimate errors due to dynamic and measurement-related error sources are affected by the process noise level used. This information is then used to establish

  1. Physiological and lifestyle factors contributing to risk and severity of peri-orbital dark circles in the Brazilian population*

    PubMed Central

    Matsui, Mary S; Schalka, Sérgio; Vanderover, Garrett; Fthenakis, Christina G.; Christopher, J; Bombarda, Patricia Camarano Pinto; Bueno, Juliana Regina; Viscomi, Bianca Lenci Inácio; Bombarda Júnior, Mário Sérgio

    2015-01-01

    BACKGROUND Peri-orbital dark circles are a cosmetic concern worldwide, and have been attributed to hyperpigmentation from allergy or atopic dermatitis, blood stasis, structural shadowing effects, and a thin epidermis/dermis under the eye. It is of interest to better understand lifestyle and demographic risk factors and the relative impact of melanin, blood and epidermal/dermal factors on the severity of Peri-orbital dark circles. OBJECTIVE To compare by non-invasive imaging the impact of biological factors to a visual grading scale for Peri-orbital dark circles, and test the correlation of various demographic factors with Peri-orbital dark circles. METHODS Subjects completed a lifestyle and health survey, and Peri-orbital dark circles severity was evaluated using standardized photographs. Hyperspectral image analysis was used to assess the contributions of melanin, blood volume, degree of blood oxygen saturation, and dermal scattering. RESULTS Family history was the most significant risk factor for Peri-orbital dark circles. The average age of onset was 24 years, and earlier onset correlated with higher severity scores. Asthma was significantly associated with Peri-orbital dark circles scores, but self-reported allergy was not. In this study, sleep was not correlated with Peri-orbital dark circles scores. Hyperspectral imaging indicated that melanin was the dominant correlate for Peri-orbital dark circles severity, while oxygen saturation was secondary. The difference between under-eye and cheek measurements for ∆L*and ∆E* were the most significant instrumental parameters correlated with visual assessment of Peri-orbital dark circles severity. CONCLUSION Although typically associated with lack of sleep, risk of Peri-orbital dark circles is primarily hereditary. The main factors contributing to the appearance of Peri-orbital dark circles are melanin and (deoxygenated) blood. PMID:26375218

  2. Orbit Processing and Analysis of a GEO Class of High Area-to-Mass Ratio Debris Objects

    NASA Astrophysics Data System (ADS)

    Kelecy, T.; Deiotte, R.; Africano, J.; Stansberry, G.; Payne, T.

    A population of recently discovered deep space objects is thought to be debris having origins from sources in the geosynchronous orbit (GEO) belt. Observations have been presented indicating that these objects have a high area-to-mass (A/M) ratio (1's to 10's of m2/kg), and thus would explain the observed migration of eccentricity (0.1-0.6) and inclination that distinguishes their orbital characteristics. There is a heightened interest in the international community due to the large number and small size of these objects, as they pose a hazard to active satellites operating in the vicinity of the GEO belt. Observational coverage of these objects has been limited by the orbital phasing and the locations of the tracking sites. Boeing, NASA and the U.S. Air Force Space Command have embarked on a collaborative effort with the Inter-Agency Space Debris Coordination Committee (IADC) to track selected high A/m of this population to more accurately characterize their orbits and orbit histories. Space Command tracking assets were tasked to provide angles measurements for representative set of 6 high A/m objects, and the data were used to establish a process for doing orbit updates that would accommodate a priori two-line element sets that will eventually be provided by the IADC. This paper presents the development and validation of the data processing and orbit update implementation, and preliminary analysis results of the high A/m class of objects. Limitations in the observational geometry, along with the apparent time variations in the nominal A/m values of some of the objects, pose a challenge for the orbit prediction. The ultimate goal is to establish a process that will provide long-term, relatively accurate orbital histories for these high A/m objects derived from a global set of observation metrics, and to capture photometric measurements when possible that will support characterization of these objects.

  3. Expressions Module for the Satellite Orbit Analysis Program

    NASA Technical Reports Server (NTRS)

    Edmonds, Karina

    2008-01-01

    The Expressions Module is a software module that has been incorporated into the Satellite Orbit Analysis Program (SOAP). The module includes an expressions- parser submodule built on top of an analytical system, enabling the user to define logical and numerical variables and constants. The variables can capture output from SOAP orbital-prediction and geometric-engine computations. The module can combine variables and constants with built-in logical operators (such as Boolean AND, OR, and NOT), relational operators (such as >, <, or =), and mathematical operators (such as addition, subtraction, multiplication, division, modulus, exponentiation, differentiation, and integration). Parentheses can be used to specify precedence of operations. The module contains a library of mathematical functions and operations, including logarithms, trigonometric functions, Bessel functions, minimum/ maximum operations, and floating- point-to-integer conversions. The module supports combinations of time, distance, and angular units and has a dimensional- analysis component that checks for correct usage of units. A parser based on the Flex language and the Bison program looks for and indicates errors in syntax. SOAP expressions can be built using other expressions as arguments, thus enabling the user to build analytical trees. A graphical user interface facilitates use.

  4. A general methodology for population analysis

    NASA Astrophysics Data System (ADS)

    Lazov, Petar; Lazov, Igor

    2014-12-01

    For a given population with N - current and M - maximum number of entities, modeled by a Birth-Death Process (BDP) with size M+1, we introduce utilization parameter ρ, ratio of the primary birth and death rates in that BDP, which, physically, determines (equilibrium) macrostates of the population, and information parameter ν, which has an interpretation as population information stiffness. The BDP, modeling the population, is in the state n, n=0,1,…,M, if N=n. In presence of these two key metrics, applying continuity law, equilibrium balance equations concerning the probability distribution pn, n=0,1,…,M, of the quantity N, pn=Prob{N=n}, in equilibrium, and conservation law, and relying on the fundamental concepts population information and population entropy, we develop a general methodology for population analysis; thereto, by definition, population entropy is uncertainty, related to the population. In this approach, what is its essential contribution, the population information consists of three basic parts: elastic (Hooke's) or absorption/emission part, synchronization or inelastic part and null part; the first two parts, which determine uniquely the null part (the null part connects them), are the two basic components of the Information Spectrum of the population. Population entropy, as mean value of population information, follows this division of the information. A given population can function in information elastic, antielastic and inelastic regime. In an information linear population, the synchronization part of the information and entropy is absent. The population size, M+1, is the third key metric in this methodology. Namely, right supposing a population with infinite size, the most of the key quantities and results for populations with finite size, emerged in this methodology, vanish.

  5. Independent Orbiter Assessment (IOA): Analysis of the manned maneuvering unit

    NASA Technical Reports Server (NTRS)

    Bailey, P. S.

    1986-01-01

    Results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve indepedence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Manned Maneuvering Unit (MMU) hardware. The MMU is a propulsive backpack, operated through separate hand controllers that input the pilot's translational and rotational maneuvering commands to the control electronics and then to the thrusters. The IOA analysis process utilized available MMU hardware drawings and schematics for defining hardware subsystems, assemblies, components, and hardware items. Final levels of detail were evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the worst case severity of the effect for each identified failure mode. The IOA analysis of the MMU found that the majority of the PCIs identified are resultant from the loss of either the propulsion or control functions, or are resultant from inability to perform an immediate or future mission. The five most severe criticalities identified are all resultant from failures imposed on the MMU hand controllers which have no redundancy within the MMU.

  6. Space Debris Attitude Simulation - IOTA (In-Orbit Tumbling Analysis)

    NASA Astrophysics Data System (ADS)

    Kanzler, R.; Schildknecht, T.; Lips, T.; Fritsche, B.; Silha, J.; Krag, H.

    Today, there is little knowledge on the attitude state of decommissioned intact objects in Earth orbit. Observational means have advanced in the past years, but are still limited with respect to an accurate estimate of motion vector orientations and magnitude. Especially for the preparation of Active Debris Removal (ADR) missions as planned by ESA's Clean Space initiative or contingency scenarios for ESA spacecraft like ENVISAT, such knowledge is needed. The In-Orbit Tumbling Analysis tool (IOTA) is a prototype software, currently in development within the framework of ESA's “Debris Attitude Motion Measurements and Modelling” project (ESA Contract No. 40000112447), which is led by the Astronomical Institute of the University of Bern (AIUB). The project goal is to achieve a good understanding of the attitude evolution and the considerable internal and external effects which occur. To characterize the attitude state of selected targets in LEO and GTO, multiple observation methods are combined. Optical observations are carried out by AIUB, Satellite Laser Ranging (SLR) is performed by the Space Research Institute of the Austrian Academy of Sciences (IWF) and radar measurements and signal level determination are provided by the Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR). Developed by Hyperschall Technologie Göttingen GmbH (HTG), IOTA will be a highly modular software tool to perform short- (days), medium- (months) and long-term (years) propagation of the orbit and attitude motion (six degrees-of-freedom) of spacecraft in Earth orbit. The simulation takes into account all relevant acting forces and torques, including aerodynamic drag, solar radiation pressure, gravitational influences of Earth, Sun and Moon, eddy current damping, impulse and momentum transfer from space debris or micro meteoroid impact, as well as the optional definition of particular spacecraft specific influences like tank sloshing, reaction wheel behaviour

  7. Secondary Eclipse Observations and Orbital Analysis of WASP-32b

    NASA Astrophysics Data System (ADS)

    Garland, Justin; Harrington, Joseph; Cubillos, Patricio; Blecic, Jasmina; Foster, Andrew S.; Bowman, Oliver; Maxted, Pierre F. L.

    2016-01-01

    We report two Spitzer secondary eclipses of the exoplanet WASP-32b. Discovered by Maxted et al. (2010), this hot-Jupiter planet has a mass of 3.6 ± 0.07 MJ a radius of 1.18 ± 0.07 RJ and an orbital period of 2.71865 ± 0.00008 days around a G-type star. We observed two secondary eclipses in the 3.6 μm and 4.5 μm channels using the Spitzer Space Telescope in 2010 as a part of the Spitzer Exoplanet Target of Opportunity program (program 60003). We present eclipse depth estimates of 0.0013 ± 0.00023 in the 4.5 μm band and inconclusive results in the 3.6 μm band. We also report an infrared brightness temperature of 1538 ± 110 in the 4.5 μm channel and refinements of orbital parameters for WASP-32b from our eclipse measurement as well as amatuer and professional data that closely match previous results. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This work was supported by NASA Planetary Atmospheres grant NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G. JB holds a NASA Earth and Space Science Fellowship.

  8. Orbit determination error analysis and comparison of station-keeping costs for Lissajous and halo-type libration point orbits and sensitivity analysis using experimental design techniques

    NASA Technical Reports Server (NTRS)

    Gordon, Steven C.

    1993-01-01

    Spacecraft in orbit near libration point L1 in the Sun-Earth system are excellent platforms for research concerning solar effects on the terrestrial environment. One spacecraft mission launched in 1978 used an L1 orbit for nearly 4 years, and future L1 orbital missions are also being planned. Orbit determination and station-keeping are, however, required for these orbits. In particular, orbit determination error analysis may be used to compute the state uncertainty after a predetermined tracking period; the predicted state uncertainty levels then will impact the control costs computed in station-keeping simulations. Error sources, such as solar radiation pressure and planetary mass uncertainties, are also incorporated. For future missions, there may be some flexibility in the type and size of the spacecraft's nominal trajectory, but different orbits may produce varying error analysis and station-keeping results. The nominal path, for instance, can be (nearly) periodic or distinctly quasi-periodic. A periodic 'halo' orbit may be constructed to be significantly larger than a quasi-periodic 'Lissajous' path; both may meet mission requirements, but perhaps the required control costs for these orbits are probably different. Also for this spacecraft tracking and control simulation problem, experimental design methods can be used to determine the most significant uncertainties. That is, these methods can determine the error sources in the tracking and control problem that most impact the control cost (output); it also produces an equation that gives the approximate functional relationship between the error inputs and the output.

  9. Orbit Determination Covariance Analysis for the Europa Clipper Mission

    NASA Technical Reports Server (NTRS)

    Ionasescu, Rodica; Martin-Mur, Tomas; Valerino, Powtawche; Criddle, Kevin; Buffington, Brent; McElrath, Timothy

    2014-01-01

    A new Jovian satellite tour is proposed by NASA, which would include numerous flybys of the moon Europa, and would explore its potential habitability by characterizing the existence of any water within and beneath Europa's ice shell. This paper describes the results of a covariance study that was undertaken on a sample tour to assess the navigational challenges and capabilities of such a mission from an orbit determination (OD) point of view, and to help establish a delta V budget for the maneuvers needed to keep the spacecraft on the reference trajectory. Additional parametric variations from the baseline case were also investigated. The success of the Europa Clipper mission will depend on the science measurements that it will enable. Meeting the requirements of the instruments onboard the spacecraft is an integral part of this analysis.

  10. Theoretical analysis of the density within an orbiting molecular shield

    NASA Technical Reports Server (NTRS)

    Hueser, J. E.; Brock, F. J.

    1976-01-01

    An analytical model based on the kinetic theory of a drifting Maxwellian gas is used to determine the nonequilibrium molecular density distribution within a hemispherical shell open aft with its axis parallel to its velocity. Separate numerical results are presented for the primary and secondary density distribution components due to the drifting Maxwellian gas for speed ratios between 2.5 and 10. An analysis is also made of the density component due to gas desorbed from the wall of the hemisphere, and numerical results are presented for the density distribution. It is shown that the adsorption process may be completely ignored. The results are applicable to orbital trajectories in any planet-atmosphere system and interplanetary transfer trajectories. Application to the earth's atmosphere is mentioned briefly.

  11. Singular perturbation analysis of the atmospheric orbital plane change problem

    NASA Technical Reports Server (NTRS)

    Calise, A. J.

    1988-01-01

    A three-state model is presented for the aeroassisted orbital plane change problem. A further model order reduction to a single state model is examined using singular perturbation theory. The optimal solution for this single state model compares favorably with the exact numerical solution using a four-state model; however, a separate boundary layer solution is required to satisfy the terminal constraint on altitude. This, in general, involves the solution of a two-point boundary value problem, but for a two-state model. An approximation is introduced to obtain an analytical control solution for lift and bank angle. Included are numerical simulation results of a guidance law derived from this analysis, along with comparison to earlier work by other researchers.

  12. Contribution Analysis of BDS/GPS Combined Orbit Determination

    NASA Astrophysics Data System (ADS)

    Zhang, Qin

    2016-07-01

    BeiDou Navigation Satellite System (BDS) does not have the ability of global navigation and positioning currently. The whole tracking observation of satellite orbit and the geometry of reference station are not perfect. These situations influence the accuracy of satellite orbit determination. Based on the theory and method of dynamic orbit determination, the analytical contribution of multi-GNSS combined orbit determination to the solution precision of parameters was derived. And using the measured data, the statistical contribution of BDS/GPS combined orbit determination to the solution precision of orbit and clock error was analyzed. The results show that the contribution of combined orbit determination to the solution precision of the common parameters between different systems was significant. The solution precisions of the orbit and clock error were significantly improved except GEO satellites. The statistical contribution of BDS/GPS combined orbit determination to the precision of BDS satellite orbit, the RMS of BDS satellite clock error and the RMS of receiver clock error were 36.21%, 26.88% and 20.88% respectively. Especially, the contribution to the clock error of receivers which were in the area with few visible satellites was particularly significant. And the statistical contribution was 45.95%.

  13. Traveling Waves Connecting Equilibrium and Periodic Orbit for a Delayed Population Model on a Two-Dimensional Spatial Lattice

    NASA Astrophysics Data System (ADS)

    Cheng, Cui-Ping; Li, Wan-Tong; Wang, Zhi-Cheng; Zheng, Shenzhou

    This paper is concerned with the existence of fast traveling waves connecting an equilibrium and a periodic orbit in a delayed population model with stage structure on a two-dimensional spatial lattice, under the assumption that the corresponding ODEs have heteroclinic orbits connecting an equilibrium point and a periodic solution. In this work, we rewrite the mixed functional differential equation as an integral equation in a Banach space and analyze the corresponding linear operator. Our approach eventually reduces a singular perturbation problem to a regular perturbation problem. The existence of traveling wave solution therefore is obtained by using the Liapunov-Schmidt method and implicit function theorem.

  14. Population Analysis: Communicating About Anthropometry in Context

    NASA Technical Reports Server (NTRS)

    Thaxton, Sherry; Rajulu, Sudhakar

    2009-01-01

    This slide presentation reviews the importance of communications about anthropometry and population analysis in particular for the design of aerospace systems. The difficulty of providing anthropometric accomodation an entire range of the population is reviewed, and the importance of communication of the issues with human system integration is emphasized, and the analysis of population as it applies to existing human factors methodologies is a novel way to assist with the communication. The issues of space suit design and anthropometry is reviewed as an example.

  15. MSFC Skylab Orbital Workshop, volume 1. [systems analysis and equipment specifications for orbital laboratory

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technical aspects of the Skylab-Orbital Workshop are discussed. Original concepts, goals, design philosophy, hardware, and testing are reported. The final flight configuration, overall test program, and mission performance are analyzed. The systems which are examined are: (1) the structural system, (2) the meteoroid shield systems, and (3) the environmental/thermal control subsystem.

  16. Analysis of orbital configurations for geocenter determination with GPS and low-Earth orbiters

    NASA Astrophysics Data System (ADS)

    Kuang, Da; Bar-Sever, Yoaz; Haines, Bruce

    2015-05-01

    We use a series of simulated scenarios to characterize the observability of geocenter location with GPS tracking data. We examine in particular the improvement realized when a GPS receiver in low Earth orbit (LEO) augments the ground network. Various orbital configurations for the LEO are considered and the observability of geocenter location based on GPS tracking is compared to that based on satellite laser ranging (SLR). The distance between a satellite and a ground tracking-site is the primary measurement, and Earth rotation plays important role in determining the geocenter location. Compared to SLR, which directly and unambiguously measures this distance, terrestrial GPS observations provide a weaker (relative) measurement for geocenter location determination. The estimation of GPS transmitter and receiver clock errors, which is equivalent to double differencing four simultaneous range measurements, removes much of this absolute distance information. We show that when ground GPS tracking data are augmented with precise measurements from a GPS receiver onboard a LEO satellite, the sensitivity of the data to geocenter location increases by more than a factor of two for Z-component. The geometric diversity underlying the varying baselines between the LEO and ground stations promotes improved global observability, and renders the GPS technique comparable to SLR in terms of information content for geocenter location determination. We assess a variety of LEO orbital configurations, including the proposed orbit for the geodetic reference antenna in space mission concept. The results suggest that a retrograde LEO with altitude near 3,000 km is favorable for geocenter determination.

  17. Orbit Determination Accuracy Analysis of the Magnetospheric Multiscale Mission During Perigee Raise

    NASA Technical Reports Server (NTRS)

    Pachura, Daniel A.; Vavrina, Matthew A.; Carpenter, J. R.; Wright, Cinnamon A.

    2014-01-01

    The Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) will provide orbit determination and prediction support for the Magnetospheric Multiscale (MMS) mission during the missions commissioning period. The spacecraft will launch into a highly elliptical Earth orbit in 2015. Starting approximately four days after launch, a series of five large perigee-raising maneuvers will be executed near apogee on a nearly every-other-orbit cadence. This perigee-raise operations concept requires a high-accuracy estimate of the orbital state within one orbit following the maneuver for performance evaluation and a high-accuracy orbit prediction to correctly plan and execute the next maneuver in the sequence. During early mission design, a linear covariance analysis method was used to study orbit determination and prediction accuracy for this perigee-raising campaign. This paper provides a higher fidelity Monte Carlo analysis using the operational COTS extended Kalman filter implementation that was performed to validate the linear covariance analysis estimates and to better characterize orbit determination performance for actively maneuvering spacecraft in a highly elliptical orbit. The study finds that the COTS extended Kalman filter tool converges on accurate definitive orbit solutions quickly, but prediction accuracy through orbits with very low altitude perigees is degraded by the unpredictability of atmospheric density variation.

  18. Orbit Determination Accuracy Analysis of the Magnetospheric Multiscale Mission During Perigee Raise

    NASA Technical Reports Server (NTRS)

    Pachura, Daniel A.; Vavrina, Matthew A.; Carpenter, J. Russell; Wright, Cinnamon A.

    2014-01-01

    The Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) will provide orbit determination and prediction support for the Magnetospheric Multiscale (MMS) mission during the mission's commissioning period. The spacecraft will launch into a highly elliptical Earth orbit in 2015. Starting approximately four days after launch, a series of five large perigee-raising maneuvers will be executed near apogee on a nearly every-other-orbit cadence. This perigee-raise operations concept requires a high-accuracy estimate of the orbital state within one orbit following the maneuver for performance evaluation and a high-accuracy orbit prediction to correctly plan and execute the next maneuver in the sequence. During early mission design, a linear covariance analysis method was used to study orbit determination and prediction accuracy for this perigee-raising campaign. This paper provides a higher fidelity Monte Carlo analysis using the operational COTS extended Kalman filter implementation that was performed to validate the linear covariance analysis estimates and to better characterize orbit determination performance for actively maneuvering spacecraft in a highly elliptical orbit. The study finds that the COTS extended Kalman filter tool converges on accurate definitive orbit solutions quickly, but prediction accuracy through orbits with very low altitude perigees is degraded by the unpredictability of atmospheric density variation.

  19. Analysis on the long term orbital evolution of Molniya satellites

    NASA Astrophysics Data System (ADS)

    Zhu, Ting-Lei; Zhao, Chang-Yin; Wang, Hong-Bo; Zhang, Ming-Jiang

    2015-06-01

    Long term evolution of the Molniya satellites are investigated by means of historical data analysis, theoretical analysis and numerical integration. Both the mean motion resonance problem and the critical inclination problem are studied. The period and the amplitude of the semi-major axis for each satellite are obtained analytically and compared with the observational data. In addition, the reason of the observed sudden changes in the center and the amplitude of the oscillating semi-major axes is determined as the effect of the atmosphere drag. For the long period perigee motion, the dominant perturbations come from the luni-solar gravity. A two-degree-of freedom system is established by adding the two periodic terms of the neighbor resonances to the Hamiltonian of the classical single resonance model. In theory, the resulting resonance overlap model is responsible for the chaotic layer between the libration region and the circulation region. In practice, it is applied to explain the quick decay of the earliest Molniya satellites and to study the satellites that still orbiting the Earth at present.

  20. Analysis of magnetic field data from Pioneer Venus orbiter

    NASA Technical Reports Server (NTRS)

    Russell, Christopher T.

    1994-01-01

    The subject grant (NAG 2-501) supported the analysis of magnetic field data from the Pioneer Venus orbiter for the period 10/1/87 to 9/30/94. During that period, 188 papers were contributed to scientific meetings that either analyzed the magnetometer data or used the data as part of the analysis of a scientific problem. Further, 107 papers were published in research journals and books. The magnetic moment of Venus was described. Venus was found to be essentially devoid of any intrinsic magnetic field. There was evidence though for the presence of lightning in the Venus atmosphere. The altitude distribution of impulsive signals in the night atmosphere was mapped and geographic clusters were found, most probably associated with local time ordering. A new means to create flux ropes in the ionosphere was postulated. On the nightside, ionospheric holes, ionospheric clouds, and tail rays were studied. The subsolar ionopause and the magnetic barrier were examined as was the altitude asymmetry of the ionopause, properties of the magnetosheath, and location of the bow shock upstream waves.

  1. Missions to Titan /1983-2000/ - An analysis of orbiters and entry vehicles

    NASA Technical Reports Server (NTRS)

    Hendricks, T. C.; Satin, A. L.; Tindle, E.

    1976-01-01

    Mission Analysis data is presented which forms a basis for planning future missions to Titan, the seventh moon of Saturn. Four Titan mission options are studied: orbiters, probes, penetrators and landers. The generated data supports these mission modes. A comprehensive launch and trajectory analysis of earth to Saturn opportunities from 1983 to 2000 is given. Direct ballistic and Delta VEGA trajectory modes are evaluated. Orbital insertion, orbital trim, entry vehicle deployment options are all studied in parametric detail.

  2. Orbiter subsystem hardware/software interaction analysis. Volume 8: Forward reaction control system

    NASA Technical Reports Server (NTRS)

    Becker, D. D.

    1980-01-01

    The results of the orbiter hardware/software interaction analysis for the AFT reaction control system are presented. The interaction between hardware failure modes and software are examined in order to identify associated issues and risks. All orbiter subsystems and interfacing program elements which interact with the orbiter computer flight software are analyzed. The failure modes identified in the subsystem/element failure mode and effects analysis are discussed.

  3. The Cluster Analysis of the Databases of the Orbital Parameters of Artificial Satellites

    NASA Astrophysics Data System (ADS)

    Shakun, L. S.; Koshkin, N. I.

    Cluster analysis of database of orbit parameters of artificial satellites. L.Shakun, N.Koshkin. The relational base of orbital parameters of near-Earth space objects (SO) is created. For 2007 it is led correlative and cluster analysis on variations of values A* for 4.5 thousand of low-Earth orbit (LEO) objects. Clusters LEO with similar character of atmospheric drag are selected.

  4. Orbit Determination Error Analysis Results for the Triana Sun-Earth L2 Libration Point Mission

    NASA Technical Reports Server (NTRS)

    Marr, G.

    2003-01-01

    Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination error analysis results are presented for all phases of the Triana Sun-Earth L1 libration point mission and for the science data collection phase of a future Sun-Earth L2 libration point mission. The Triana spacecraft was nominally to be released by the Space Shuttle in a low Earth orbit, and this analysis focuses on that scenario. From the release orbit a transfer trajectory insertion (TTI) maneuver performed using a solid stage would increase the velocity be approximately 3.1 km/sec sending Triana on a direct trajectory to its mission orbit. The Triana mission orbit is a Sun-Earth L1 Lissajous orbit with a Sun-Earth-vehicle (SEV) angle between 4.0 and 15.0 degrees, which would be achieved after a Lissajous orbit insertion (LOI) maneuver at approximately launch plus 6 months. Because Triana was to be launched by the Space Shuttle, TTI could potentially occur over a 16 orbit range from low Earth orbit. This analysis was performed assuming TTI was performed from a low Earth orbit with an inclination of 28.5 degrees and assuming support from a combination of three Deep Space Network (DSN) stations, Goldstone, Canberra, and Madrid and four commercial Universal Space Network (USN) stations, Alaska, Hawaii, Perth, and Santiago. These ground stations would provide coherent two-way range and range rate tracking data usable for orbit determination. Larger range and range rate errors were assumed for the USN stations. Nominally, DSN support would end at TTI+144 hours assuming there were no USN problems. Post-TTI coverage for a range of TTI longitudes for a given nominal trajectory case were analyzed. The orbit determination error analysis after the first correction maneuver would be generally applicable to any libration point mission utilizing a direct trajectory.

  5. Analysis of the Radio Astronomy Explorer lunar orbit mission.

    NASA Technical Reports Server (NTRS)

    Groves, R. T.

    1972-01-01

    The second Radio Astronomy Explorer spacecraft (RAE-B) is planned to be inserted into lunar orbit in 1973. The transfer trajectory design, lunar orbit selection and launch opportunities are developed in relation to the spacecraft mass properties, propulsion capability and the scientific, environmental and engineering constraints. Alternative midcourse guidance and lunar orbit trim strategies are analyzed and compared. A means of achieving a launch window without varying launch azimuth and park orbit coast time is described. The resulting mission design is characterized by near-minimum energy lunar transfer trajectories and low eccentricity, retrograde critical inclination lunar orbits. Acceptable launch periods are shown to exist for six consecutive months and for two to four consecutive days per month.

  6. Geosynchronous earth orbit/low earth orbit space object inspection and debris disposal: A preliminary analysis using a carrier satellite with deployable small satellites

    NASA Astrophysics Data System (ADS)

    Crockett, Derick

    Detailed observations of geosynchronous satellites from earth are very limited. To better inspect these high altitude satellites, the use of small, refuelable satellites is proposed. The small satellites are stationed on a carrier platform in an orbit near the population of geosynchronous satellites. A carrier platform equipped with deployable, refuelable SmallSats is a viable option to inspect geosynchronous satellites. The propellant requirement to transfer to a targeted geosynchronous satellite, perform a proximity inspection mission, and transfer back to the carrier platform in a nearby orbit is determined. Convex optimization and traditional optimization techniques are explored, determining minimum propellant trajectories. Propellant is measured by the total required change in velocity, delta-v. The trajectories were modeled in a relative reference frame using the Clohessy-Wiltshire equations. Mass estimations for the carrier platform and the SmallSat were determined by using the rocket equation. The mass estimates were compared to the mass of a single, non-refuelable satellite performing the same geosynchronous satellite inspection missions. From the minimum delta-v trajectories and the mass analysis, it is determined that using refuelable SmallSats and a carrier platform in a nearby orbit can be more efficient than using a single non-refuelable satellite to perform multiple geosynchronous satellite inspections.

  7. Principal Components Analysis of Population Admixture

    PubMed Central

    Ma, Jianzhong; Amos, Christopher I.

    2012-01-01

    With the availability of high-density genotype information, principal components analysis (PCA) is now routinely used to detect and quantify the genetic structure of populations in both population genetics and genetic epidemiology. An important issue is how to make appropriate and correct inferences about population relationships from the results of PCA, especially when admixed individuals are included in the analysis. We extend our recently developed theoretical formulation of PCA to allow for admixed populations. Because the sampled individuals are treated as features, our generalized formulation of PCA directly relates the pattern of the scatter plot of the top eigenvectors to the admixture proportions and parameters reflecting the population relationships, and thus can provide valuable guidance on how to properly interpret the results of PCA in practice. Using our formulation, we theoretically justify the diagnostic of two-way admixture. More importantly, our theoretical investigations based on the proposed formulation yield a diagnostic of multi-way admixture. For instance, we found that admixed individuals with three parental populations are distributed inside the triangle formed by their parental populations and divide the triangle into three smaller triangles whose areas have the same proportions in the big triangle as the corresponding admixture proportions. We tested and illustrated these findings using simulated data and data from HapMap III and the Human Genome Diversity Project. PMID:22808102

  8. Analysis of the influence of orbital disturbances applied to an artificial lunar satellite

    NASA Astrophysics Data System (ADS)

    Gonçalves, L. D.; Rocco, E. M.; de Moraes, R. V.

    2015-10-01

    This paper analyzes the influence of the orbital disturbance forces in the trajectory of lunar satellites. The following gravitational and non-gravitational orbital disturbances are considered: the non-homogeneity of the lunar gravitational field; the gravitational attraction due to the third body, considering the Earth and the Sun; the lunar albedo; the solar radiation pressure. Numerical models were developed and implemented in an orbital trajectory simulator aiming to understand the dynamics of the orbital motion of an artificial satellite in lunar orbit when considering the simultaneous effect of all disturbances. Different orbits were simulated in order to characterize the major and the minor influence of each disturbing force as function of the inclination and the right ascension of the ascending node. This study can be very useful in the space mission analysis and in the selection of orbits less affected by environmental disturbances.

  9. Micrometeoroid and Orbital Debris (MMOD) Shield Ballistic Limit Analysis Program

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon

    2013-01-01

    This software implements penetration limit equations for common micrometeoroid and orbital debris (MMOD) shield configurations, windows, and thermal protection systems. Allowable MMOD risk is formulated in terms of the probability of penetration (PNP) of the spacecraft pressure hull. For calculating the risk, spacecraft geometry models, mission profiles, debris environment models, and penetration limit equations for installed shielding configurations are required. Risk assessment software such as NASA's BUMPERII is used to calculate mission PNP; however, they are unsuitable for use in shield design and preliminary analysis studies. The software defines a single equation for the design and performance evaluation of common MMOD shielding configurations, windows, and thermal protection systems, along with a description of their validity range and guidelines for their application. Recommendations are based on preliminary reviews of fundamental assumptions, and accuracy in predicting experimental impact test results. The software is programmed in Visual Basic for Applications for installation as a simple add-in for Microsoft Excel. The user is directed to a graphical user interface (GUI) that requires user inputs and provides solutions directly in Microsoft Excel workbooks.

  10. Pioneer Venus Orbiter Ultraviolet Spectrometer: Operations and Data Analysis

    NASA Technical Reports Server (NTRS)

    Stewart, A. I. F.

    1997-01-01

    The Pioneer Venus spacecraft orbited Venus 5,055 times between 4th December 1978 and 6th October 1992, before entering Venus' atmosphere and burning up on the latter date. On 255 of these orbits, science operations were suspended because of superior conjunction (Venus' proximity to the Sun as seen from Earth). Of the remaining 4800 orbits, about 85% yielded good-quality OUVS science data; 15% were lost to various problems, including loss of uplink (commands) to and downlink (data) from the spacecraft, errors in commanding OUVS, and one or other of the two instrument anomalies mentioned below.

  11. IgG4-related Orbital Disease and Its Mimics in a Western Population.

    PubMed

    Ferry, Judith A; Klepeis, Veronica; Sohani, Aliyah R; Harris, Nancy Lee; Preffer, Frederic I; Stone, John H; Grove, Arthur; Deshpande, Vikram

    2015-12-01

    Although chronic inflammatory disorders of the ocular adnexa are relatively common, their pathogenesis is in many cases poorly understood. Recent investigation suggests that many cases of sclerosing orbital inflammation are a manifestation of IgG4-related disease; however, most patients reported have been Asian, and it is not clear whether the results of studies from the Far East can be reliably extrapolated to draw conclusions about Western patients. We evaluated 38 cases previously diagnosed as orbital inflammatory pseudotumor or chronic dacryoadenitis to determine whether our cases fulfill the criteria for IgG4-RD (IgG4-related dacryoadenitis when involving the lacrimal gland, and IgG4-related sclerosing orbital inflammation when involving orbital soft tissue). Fifteen patients had IgG4-related dacryoadenitis or orbital inflammation. These patients included 9 men and 6 women, aged 24 to 77 years (median, 64 y). Lesions involved orbital soft tissue (8 cases), lacrimal gland (6 cases), and canthus (1 case). In 1 case, focal in situ follicular neoplasia was seen in a background of IgG4-RD. In another case, a clonal IGH gene rearrangement was detected. Four patients with IgG4-RD had evidence of IgG4-RD in other anatomic sites. Five patients, 1 man and 4 women, aged 26 to 74 years (median 50 y) had orbital lesions (2 involving lacrimal gland, 3 involving soft tissue) suspicious for, but not diagnostic of, IgG4-RD. Of 16 patients with IgG4-RD or probable IgG4-RD with information available regarding the course of their disease, 11 patients experienced recurrent or persistent orbital disease. However, no patient developed lymphoma, and no patient died of complications of IgG4-RD. Eighteen patients had lesions not representing IgG4-RD. They included 6 male and 12 female individuals aged 6 to 77 years (median, 47 y). These patients had a variety of diseases, including granulomatosis with polyangiitis (3 cases), Rosai-Dorfman disease (1 case), nonspecific chronic

  12. Scripting Module for the Satellite Orbit Analysis Program (SOAP)

    NASA Technical Reports Server (NTRS)

    Carnright, Robert; Paget, Jim; Coggi, John; Stodden, David

    2008-01-01

    This add-on module to the SOAP software can perform changes to simulation objects based on the occurrence of specific conditions. This allows the software to encompass simulation response of scheduled or physical events. Users can manipulate objects in the simulation environment under programmatic control. Inputs to the scripting module are Actions, Conditions, and the Script. Actions are arbitrary modifications to constructs such as Platform Objects (i.e. satellites), Sensor Objects (representing instruments or communication links), or Analysis Objects (user-defined logical or numeric variables). Examples of actions include changes to a satellite orbit ( v), changing a sensor-pointing direction, and the manipulation of a numerical expression. Conditions represent the circumstances under which Actions are performed and can be couched in If-Then-Else logic, like performing v at specific times or adding to the spacecraft power only when it is being illuminated by the Sun. The SOAP script represents the entire set of conditions being considered over a specific time interval. The output of the scripting module is a series of events, which are changes to objects at specific times. As the SOAP simulation clock runs forward, the scheduled events are performed. If the user sets the clock back in time, the events within that interval are automatically undone. This script offers an interface for defining scripts where the user does not have to remember the vocabulary of various keywords. Actions can be captured by employing the same user interface that is used to define the objects themselves. Conditions can be set to invoke Actions by selecting them from pull-down lists. Users define the script by selecting from the pool of defined conditions. Many space systems have to react to arbitrary events that can occur from scheduling or from the environment. For example, an instrument may cease to draw power when the area that it is tasked to observe is not in view. The contingency

  13. Orbital analysis of two-color laser ranging

    NASA Astrophysics Data System (ADS)

    Schillak, S. R.

    2013-12-01

    The poster presents the results of analysis of Zimmerwald SLR data for two colors 423nm and 846 nm. Two-color laser ranging were performed by Zimmerwald SLR station from August 2002 to January 2008. The results in each color were treated as two independent stations 7810 Blue and 7810 Infrared. The station positions were determined by NASA Goddard's orbital program GEODYN-II from results of LAGEOS-1 and LAGEOS-2 satellites. The NEU positions stability were equal to 3.5 mm (N), 3.2 mm (E), 16.5 mm (U) for blue and 3.2 mm (N), 2.9 mm (E), 14.6 (U) for infrared. In the period of study were 47 common monthly points for both colors. The difference between N, E, U components in blue and infrared for common points were equal to 0.8×2.0 mm, 0.4×1.9 mm and -4.8×8.7 mm respectively. The differences between Range Biases for both colors independently for LAGEOS-1 and LAGEOS-2 were equal to -5.7×8.6 mm and for -5.0×9.5 mm respectively. The same for both satellites annual wave with amplitude 10 mm was detected. This effect can to be explain by differences in atmospheric correction for each color. This same analysis for station Concepcion (7405) couldn't to be performed due to only 8 common points. In future very important should be laser ranging in two-colors 532 nm and 1064 nm for confirmation presented here results, especially that a new sensitive APD detectors for 1064 nm are now available. The atmospheric correction is critical for SLR accuracy upgrading.

  14. Molecular orbital analysis of dicarbido-transition-metal cluster compounds

    SciTech Connect

    Halet, J.; Mingos, D.M.P.

    1988-01-01

    Molecular orbital calculations on dicarbido-transition-metal carbonyl cluster compounds have shown that the bonding between C/sub 2/ and the metal cage results primarily from electron donation from the C/sub 2/ sigma/sub rho/- and ..pi..-bonding molecular orbitals and back donation from filled metallic molecular orbitals to the C/sub 2/ ..pi..* orbitals. The bonding therefore follows closely the Chatt-Dewar-Ducanson model that has been established previously for ethyne and ethene complexes but not for interstitial moieties. The C-C separation in the dicarbido clusters depends critically on the geometric constraints imposed by the metal cage and the extent of forward and back donation. In these clusters where the carbon atoms are in adjacent trigonal-prismatic sites the calculated formal bond order is between 1.0 and 1.5, which agrees well with the observed C-C bond lengths.

  15. Information services platforms at geosynchronous earth orbit: A requirements analysis

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The potential user requirements for Information Services Platforms at geosynchronous orbits were investigated. A rationale for identifying the corollary system requirements and supporting research and technology needs was provided.

  16. Analysis of HY2A precise orbit determination using DORIS

    NASA Astrophysics Data System (ADS)

    Gao, Fan; Peng, Bibo; Zhang, Yu; Evariste, Ngatchou Heutchi; Liu, Jihua; Wang, Xiaohui; Zhong, Min; Lin, Mingsen; Wang, Nazi; Chen, Runjing; Xu, Houze

    2015-03-01

    HY2A is the first Chinese marine dynamic environment satellite. The payloads include a radar altimeter to measure the sea surface height in combination with a high precision orbit to be determined from tracking data. Onboard satellite tracking includes GPS, SLR, and the DORIS DGXX receiver which delivers phase and pseudo-range measurements. CNES releases raw phase and pseudo-range measurements with RINEX DORIS 3.0 format and pre-processed Doppler range-rate with DORIS 2.2 data format. However, the VMSI software package developed by Van Martin Systems, Inc which is used to estimate HY2A DORIS orbits can only process Doppler range-rate but not the DORIS phase data which are available with much shorter latency. We have proposed a method of constructing the phase increment data, which are similar to range-rate data, from RINEX DORIS 3.0 phase data. We compute the HY2A orbits from June, 2013 to August, 2013 using the POD strategy described in this paper based on DORIS 2.2 range-rate data and our reconstructed phase increment data. The estimated orbits are evaluated by comparing with the CNES precise orbits and SLR residuals. Our DORIS-only orbits agree with the precise GPS + SLR + DORIS CNES orbits radially at 1-cm and about 3-cm in the other two directions. SLR test with the 50° cutoff elevation shows that the CNES orbit can achieve about 1.1-cm accuracy in radial direction and our DORIS-only POD solutions are slightly worse. In addition, other HY2A DORIS POD concerns are discussed in this paper. Firstly, we discuss the frequency offset values provided with the RINEX data and find that orbit accuracy for the case when the frequency offset is applied is worse than when it is not applied. Secondly, HY2A DORIS antenna z-offsets are estimated using two kinds of measurements from June, 2013 to August, 2013. The results show that the measurement errors contribute a total of about 2-cm difference of estimated z-offset. Finally, we estimate HY2A orbits selecting 3 days with

  17. Analysis of spacecraft on-orbit anomalies and lifetimes

    NASA Technical Reports Server (NTRS)

    Bloomquist, C.; Graham, W.

    1983-01-01

    Analyses of the on-orbit performance of forty-four unmanned NASA spacecraft are presented. Included are detailed descriptions and classifications of over 600 anomalies; each anomalous incident represents one reported deviation from expected spacecraft performance. Charts depicting satellite lifetimes and the performance of their major subsystems are included. Engineering analyses to further investigate the kinds and frequencies of various classes of anomalies have been conducted. An improved method for charting spacecraft capability as a function of time on orbit is explored.

  18. Unmanned, space-based, reusable orbital transfer vehicle, DARVES. Volume 1: Trade analysis and design

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The design of an unmanned, space-based, reusable Orbital Transfer Vehicle (OTV) is presented. This OTV will be utilized for the delivery and retrieval of satellites from geosynchronous Earth orbit (GEO) in conjunction with a space station assumed to be in existence in low Earth orbit (LEO). The trade analysis used to determine the vehicle design is presented, and from this study a vehicle definition is given.

  19. Analysis of periodic orbits about the Martian moons by continuation techniques

    NASA Astrophysics Data System (ADS)

    Luria, Frank

    1990-12-01

    From a few known periodic orbits of Phobos and Deimos, continuation techniques were used to find entire families of stable orbits. These techniques involved varying a parameter, the Hamiltonian, of the system and analyzing how the orbital behavior changed with the parameter. Floquet multipliers, for stability analysis, were also computed. AUTO86, a continuation/bifurcation software package, was used in this study. Artificial energy dissipation had to be added to the conservative Hamiltonian system to enable use of AUTO.

  20. Orbit determination and analysis of meteors recently observed by Finnish Fireball Network

    NASA Astrophysics Data System (ADS)

    Dmitriev, V.; Lupovla, V.; Gritsevich, M.; Lyytinen, E.; Mineeva, S.

    2015-10-01

    We perform orbit determination and analysis of three fireballs recently observed by Finnish Fireball Network (FFN). Precise orbit determination was performed by using integration of differential equations of motion. This technique was implemented into free distributable software "Meteor Toolkit". Accounting of several perturbing forces are discussed. Also estimation of accuracy of orbital elements was obtained by propagation of observational error with using covariance transformation. Long-term backward integration was provided as well.

  1. Orbital debris and meteoroid population as estimated from LDEF impact data

    NASA Technical Reports Server (NTRS)

    Zhang, Jingchang; Kessler, Donald J.

    1995-01-01

    Examination of LDEF's various surfaces shows numerous craters and holes due to hypervelocity impacts of meteoroids and man-made orbital debris. In this paper, the crater numbers as reported by Humes have been analyzed in an effort to understand the orbital debris and natural meteoroid environment in LEO. To determine the fraction of man-made to natural impacts, the side to top ratio of impacts and results of the Chemistry of Micrometeoroids Experiment are used. For craters in the 100 micron to 500 micron size range, about 25 percent to 30 percent of the impacts on the forward-facing surfaces and about 10 percent of the impacts on the trailing surfaces were estimated due to man-made orbital debris. A technique has been developed to convert crater numbers to particle fluxes, taking the fact into account that the distributions of impact velocity and incidence angle vary over the different surfaces of LDEF, as well as the ratio of the surface area flux to the cross-sectional area flux. Applying this technique, Humes' data concerning craters with limiting lip diameters of 100 micron, 200 micron and 500 micron have been converted into orbital debris and meteoroid fluxes ranging from about 20 micron to 200 micron particle diameter. The results exhibit good agreement with orbital debris model and meteoroid model. The converted meteoroid flux is slightly larger than Grun's model (by 40 to 70 percent). The converted orbital debris flux is slightly lower than Kessler's model for particle diameter smaller than about 30 micron and slightly larger than the model for particle diameter larger than about 40 micron. Taking also into account the IDE data point at about 0.8 micron particle diameter, it suggests to change the slope log (flux) versus log (diameter) of orbital debris flux in the 1 micron to 100 micron particle diameter range from 2.5 to 1.9.

  2. [Population and environment. Requests for interdisciplinary analysis].

    PubMed

    Tudela, F

    1991-01-01

    Serious difficulties impede interdisciplinary research involving demographers, ecologists, and other students of the environment. The 1st problem concerns definitions of the different subject areas. Demographers have focused on the dynamics of some indicators that reflect complex and heterogeneous population processes. The relative autonomy of demography as a discipline was gained through an empirical orientation reflected in the statistical treatment of causality. But the traditional demographic paradigm is insufficient for untangling the causal mechanisms underlying population dynamics. Environmental disciplines on the other hand face methodologic difficulties in transcending a strictly biological focus to incorporate aspects of cultural and social influence on ecological processes. "Human ecology", a possible meeting ground for ecological and demographic studies, is more of an ambitious program of transdisciplinary research than an independent discipline. Relations between the environment and development processes, including population aspects, are of increasing international concern. A conceptual base has developed in Latin America which emphasizes the global and structural aspects of the environment and of development styles. It has been extremely difficult to apply the entire conceptualization to the concrete environmental problems that are of current interest to both civil society and governments. It may be time to replace the umbrella term "environment", defining it in more specific, systemic, and operational terms. It is time to delimit study topics in terms of concrete problems. A good example would be the situation of Lake Chapala, the largest lake in Mexico. Damage caused to it cannot be assessed by referring to the "population explosion" or an "overall development style". Environmental, economic, and sociodemographic aspects will however necessarily enter the analysis. Fragile and unstable situations are of special interest in the study of relations

  3. Analysis of orbit determination for space based optical space surveillance system

    NASA Astrophysics Data System (ADS)

    Sciré, Gioacchino; Santoni, Fabio; Piergentili, Fabrizio

    2015-08-01

    The detection capability and orbit determination performance of a space based optical observation system exploiting the visible band is analyzed. The sensor characteristics, in terms of sensitivity and resolution are those typical of present state of the art star trackers. A mathematical model of the system has been built and the system performance assessed by numerical simulation. The selection of the observer satellite's has been done in order to maximize the number of observed objects in LEO, based on a statistical analysis of the space debris population in this region. The space objects' observability condition is analyzed and two batch estimator based on the Levenberg-Marquardt and on the Powell dog-leg algorithms have been implemented and their performance compared. Both the algorithms are sensitive to the initial guess. Its influence on the algorithms' convergence is assessed, showing that the Powell dog-leg, which is a trust region method, performs better.

  4. Quasiperiodic orbit analysis of nonadiabatic cis-trans photoisomerization dynamics

    NASA Astrophysics Data System (ADS)

    Balzer, Birgit; Dilthey, Stefan; Hahn, Susanne; Thoss, Michael; Stock, Gerhard

    2003-08-01

    Adopting a multidimensional model of nonadiabatic cis-trans photoisomerization, quantum-mechanical and classical simulations of the ultrafast wave-packet dynamics associated with this photoreaction are presented. The quantum calculations demonstrate that nonadiabatic photoisomerization typically leads to a largely delocalized and diffuse wave function, which hampers an intuitive understanding of the dynamics in terms of specific nuclear motion. To facilitate a classical description, a recently proposed theoretical formulation is employed that affords an exact mapping of discrete electronic states onto continuous degrees of freedom and therefore provides a well-defined classical limit of a nonadiabatically coupled system. It is shown that a simple quasiclassical implementation of the mapping formulation is able to reproduce at least qualitatively the complex quantum dynamics of the system. In addition, the classical description allows us to characterize the nonadiabatic photoisomerization dynamics in terms of a few "quasiperiodic orbits." These orbits are close to a true unstable periodic orbit but are exactly periodic only with respect to the slow reaction coordinate of the system. Various types of quasiperiodic orbits of nonadiabatic photoisomerization are identified and analyzed. It is shown that the diffuse appearance of the quantum-mechanical wave function can be directly connected to irregular classical orbits propagating on vibronically coupled potential-energy surfaces. The chaotic behavior of the system is mainly caused by the relatively high energy corresponding to photoexcitation, the large anharmonicity of the isomerization potentials, and the reflection of the trajectory at surface crossings. The results demonstrate that quasiperiodic orbits represent a concept well suited to analyze the quantum dynamics of complex systems in terms of classical trajectories without the cumbersome search for periodic orbits.

  5. Analysis of unstable periodic orbits and chaotic orbits in the one-dimensional linear piecewise-smooth discontinuous map.

    PubMed

    Rajpathak, Bhooshan; Pillai, Harish K; Bandyopadhyay, Santanu

    2015-10-01

    In this paper, we analytically examine the unstable periodic orbits and chaotic orbits of the 1-D linear piecewise-smooth discontinuous map. We explore the existence of unstable orbits and the effect of variation in parameters on the coexistence of unstable orbits. Further, we show that this structuring is different from the well known period adding cascade structure associated with the stable periodic orbits of the same map. Further, we analytically prove the existence of chaotic orbit for this map. PMID:26520067

  6. Analysis of unstable periodic orbits and chaotic orbits in the one-dimensional linear piecewise-smooth discontinuous map

    SciTech Connect

    Rajpathak, Bhooshan Pillai, Harish K.; Bandyopadhyay, Santanu

    2015-10-15

    In this paper, we analytically examine the unstable periodic orbits and chaotic orbits of the 1-D linear piecewise-smooth discontinuous map. We explore the existence of unstable orbits and the effect of variation in parameters on the coexistence of unstable orbits. Further, we show that this structuring is different from the well known period adding cascade structure associated with the stable periodic orbits of the same map. Further, we analytically prove the existence of chaotic orbit for this map.

  7. Cation-π vs anion-π interactions: a complete π-orbital analysis

    NASA Astrophysics Data System (ADS)

    Garau, Carolina; Frontera, Antonio; Quiñonero, David; Ballester, Pablo; Costa, Antoni; Deyà, Pere M.

    2004-11-01

    A complete orbital analysis of two isoelectronic complexes of trifluorobenzene (TFB), TFB ⋯ F - and TFB ⋯ Na +, as models for anion-π and cation-π interactions, respectively, has been performed at the MP2/6-31++G** level of theory. There are important orbital differences between both interactions, which are discussed in detail herein.

  8. Mars Science and Telecommunications Orbiter: Report of the Science Analysis Group, March 2006

    NASA Technical Reports Server (NTRS)

    Farmer, Crofton Barney; Calvin, Wendy M.; Campbell, Bruce; Fox, Jane; Haberle, Bob; Kasting, Jim; Luhmann, Janet; Nagy, Andy; Allen, Mark; Winterhalter, Daniel

    2006-01-01

    This document reports the findings of the Mars Science and Telecommunications Orbiter (MSTO) Science Advocacy Group (SAG), which was convened by the Mars Exploration Program Analysis Group (MEPAG) and the Mars Exploration Office at JPL to identify and prioritize areas of Mars atmospheric and surface science objectives for Mars that can be accomplished from orbit on a MSTO like mission.

  9. Physiogenomic analysis of the Puerto Rican population

    PubMed Central

    Ruaño, Gualberto; Duconge, Jorge; Windemuth, Andreas; Cadilla, Carmen L; Kocherla, Mohan; Villagra, David; Renta, Jessica; Holford, Theodore; Santiago-Borrero, Pedro J

    2009-01-01

    Aims Admixture in the population of the island of Puerto Rico is of general interest with regards to pharmacogenetics to develop comprehensive strategies for personalized healthcare in Latin Americans. This research was aimed at determining the frequencies of SNPs in key physiological, pharmacological and biochemical genes to infer population structure and ancestry in the Puerto Rican population. Materials & methods A noninterventional, cross-sectional, retrospective study design was implemented following a controlled, stratified-by-region, random sampling protocol. The sample was based on birthrates in each region of the island of Puerto Rico, according to the 2004 National Birth Registry. Genomic DNA samples from 100 newborns were obtained from the Puerto Rico Newborn Screening Program in dried-blood spot cards. Genotyping using a physiogenomic array was performed for 332 SNPs from 196 cardiometabolic and neuroendocrine genes. Population structure was examined using a Bayesian clustering approach as well as by allelic dissimilarity as a measure of allele sharing. Results The Puerto Rican sample was found to be broadly heterogeneous. We observed three main clusters in the population, which we hypothesize to reflect the historical admixture in the Puerto Rican population from Amerindian, African and European ancestors. We present evidence for this interpretation by comparing allele frequencies for the three clusters with those for the same SNPs available from the International HapMap project for Asian, African and European populations. Conclusion Our results demonstrate that population analysis can be performed with a physiogenomic array of cardiometabolic and neuroendocrine genes to facilitate the translation of genome diversity into personalized medicine. PMID:19374515

  10. Analysis of Orbital Lifetime Prediction Parameters in Preparation for Post-Mission Disposal

    NASA Astrophysics Data System (ADS)

    Choi, Ha-Yeon; Kim, Hae-Dong; Seong, Jae-Dong

    2015-12-01

    Atmospheric drag force is an important source of perturbation of Low Earth Orbit (LEO) orbit satellites, and solar activity is a major factor for changes in atmospheric density. In particular, the orbital lifetime of a satellite varies with changes in solar activity, so care must be taken in predicting the remaining orbital lifetime during preparation for post-mission disposal. In this paper, the System Tool Kit (STK®) Long-term Orbit Propagator is used to analyze the changes in orbital lifetime predictions with respect to solar activity. In addition, the STK® Lifetime tool is used to analyze the change in orbital lifetime with respect to solar flux data generation, which is needed for the orbital lifetime calculation, and its control on the drag coefficient control. Analysis showed that the application of the most recent solar flux file within the Lifetime tool gives a predicted trend that is closest to the actual orbit. We also examine the effect of the drag coefficient, by performing a comparative analysis between varying and constant coefficients in terms of solar activity intensities.

  11. Orbiter subsystem hardware/software interaction analysis. Volume 8: AFT reaction control system, part 2

    NASA Technical Reports Server (NTRS)

    Becker, D. D.

    1980-01-01

    The orbiter subsystems and interfacing program elements which interact with the orbiter computer flight software are analyzed. The failure modes identified in the subsystem/element failure mode and effects analysis are examined. Potential interaction with the software is examined through an evaluation of the software requirements. The analysis is restricted to flight software requirements and excludes utility/checkout software. The results of the hardware/software interaction analysis for the forward reaction control system are presented.

  12. Risk Analysis of On-Orbit Spacecraft Refueling Concepts

    NASA Technical Reports Server (NTRS)

    Cirillo, William M.; Stromgren, Chel; Cates, Grant R.

    2010-01-01

    On-orbit refueling of spacecraft has been proposed as an alternative to the exclusive use of Heavy-lift Launch Vehicles to enable human exploration beyond Low Earth Orbit (LEO). In these scenarios, beyond LEO spacecraft are launched dry (without propellant) or partially dry into orbit, using smaller or fewer element launch vehicles. Propellant is then launched into LEO on separate launch vehicles and transferred to the spacecraft. Refueling concepts are potentially attractive because they reduce the maximum individual payload that must be placed in Earth orbit. However, these types of approaches add significant complexity to mission operations and introduce more uncertainty and opportunities for failure to the mission. In order to evaluate these complex scenarios, the authors developed a Monte Carlo based discrete-event model that simulates the operational risks involved with such strategies, including launch processing delays, transportation system failures, and onorbit element lifetimes. This paper describes the methodology used to simulate the mission risks for refueling concepts, the strategies that were evaluated, and the results of the investigation. The results of the investigation show that scenarios that employ refueling concepts will likely have to include long launch and assembly timelines, as well as the use of spare tanker launch vehicles, in order to achieve high levels of mission success through Trans Lunar Injection.

  13. Application and analysis of satellite orbit prediction techniques

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The numerical accuracy of a satellite orbit computation program was investigated. The effects of roundoff and truncation errors on the solution were determined. New formulations that have the mean motion based on the total energy are compared to the more classical formulations and evaluated via numerical experiments.

  14. Analysis of KEK-ATF optics and coupling using orbit response matrix analysis

    SciTech Connect

    Wolski, A.; Nelson, J.; Ross, M.; Woodley, M.; Mishra, S.; /Fermilab

    2004-01-01

    LOCO is a code for analysis of the linear optics in a storage ring based on the closed orbit response to steering magnets. The analysis provides information on focusing errors, BPM gain and rotation errors, and local coupling. Here, we report the results of an application of LOCO to the KEK-ATF. Although the analysis appears to have provided useful information on the optics of the machine, it appears that one of the main aims of the study--to reduce the vertical emittance by correcting the local coupling--was not successful, and we discuss some possible reasons for this.

  15. Analysis of KEK-ATF Optics And Coupling Using Orbit Response Matrix Analysis

    SciTech Connect

    Wolski, A.; Nelson, J.; Ross, M.; Woodley, M.; Mishra, S.; /Fermilab

    2006-10-13

    LOCO is a code for analysis of the linear optics in a storage ring based on the closed orbit response to steering magnets. The analysis provides information on focusing errors, BPM gain and rotation errors, and local coupling. Here, we report the results of an application of LOCO to the KEK-ATF. Although the analysis appears to have provided useful information on the optics of the machine, it appears that one of the main aims of the study--to reduce the vertical emittance by correcting the local coupling--was not successful, and we discuss some possible reasons for this.

  16. NASA CEV On-Orbit GN&C Analysis

    NASA Technical Reports Server (NTRS)

    DSouza, Chris; Brazzel, Jack P.; Crane, Tim

    2007-01-01

    The Orion spacecraft orbit GN&C system will be required to perform both ISS servicing missions and Lunar sortie and outpost crew transportation. While certain aspects of these two missions are complementary, the two missions are also distinct in many ways. Common between the missions is a Low Earth Orbit (LEO) rendezvous, one with the ISS And the other with the LSAM/EDS stack prior to trans-lunar insertion. The lunar missions will additionally require Orion to perform orbit maintenance in LLO, perform contingency lunar orbit operations including RPOD with the LSAM, perform the TEI maneuver sequence, and execute the trans-Earth cruise. The NASA-led team developed a reference configuration orbit GN&C system capable of executing all of these activities with the same navigation sensor suite and control effectors while fully meeting the requirements being developed for System Requirements Review in advance of prime contractor selection. This paper will present an overview of the analyses performed to support system trade studies, demonstrate the feasibility of the NASA reference configuration, and validate the Orion system requirements. These analyses include linear covariance techniques, 3-DOF Monte Carlo simulations, 6-DOF Monte Carlo simulations, and analytical evaluations of GN&C systems performed by the NASA-led Orion team to characterize the sensitivities of Orion s various missions and assess the unique challenges of each. The first part of this paper will describe the trade studies that were performed in order to characterize the RPOD system performance for both the ISS and the lunar missions including development of an RPOD operations concept, RPOD trajectories, contingency scenarios, docking mechanism and associated contact conditions, post-contact thrust issues, relative navigation sensors, relative navigation sensor target infrastructure. The paper will also discuss concepts for both manually-piloted and automatically executed scenarios, as well as the

  17. Spatial uncertainty analysis of population models

    SciTech Connect

    Jager, Yetta; King, Anthony Wayne; Schumaker, Nathan; Ashwood, Tom L; Jackson, Barbara L

    2004-01-01

    This paper describes an approach for conducting spatial uncertainty analysis of spatial population models, and illustrates the ecological consequences of spatial uncertainty for landscapes with different properties. Spatial population models typically simulate birth, death, and migration on an input map that describes habitat. Typically, only a single reference map is available, but we can imagine that a collection of other, slightly different, maps could be drawn to represent a particular species' habitat. As a first approximation, our approach assumes that spatial uncertainty (i.e., the variation among values assigned to a location by such a collection of maps) is constrained by characteristics of the reference map, regardless of how the map was produced. Our approach produces lower levels of uncertainty than alternative methods used in landscape ecology because we condition our alternative landscapes on local properties of the reference map. Simulated spatial uncertainty was higher near the borders of patches. Consequently, average uncertainty was highest for reference maps with equal proportions of suitable and unsuitable habitat, and no spatial autocorrelation. We used two population viability models to evaluate the ecological consequences of spatial uncertainty for landscapes with different properties. Spatial uncertainty produced larger variation among predictions of a spatially explicit model than those of a spatially implicit model. Spatially explicit model predictions of final female population size varied most among landscapes with enough clustered habitat to allow persistence. In contrast, predictions of population growth rate varied most among landscapes with only enough clustered habitat to support a small population, i.e., near a spatially mediated extinction threshold. We conclude that spatial uncertainty has the greatest effect on persistence when the amount and arrangement of suitable habitat are such that habitat capacity is near the minimum

  18. Pioneer Venus Orbiter Ultraviolet Spectrometer: Operations and Data Analysis

    NASA Technical Reports Server (NTRS)

    Stewart, A. I. F.

    1997-01-01

    The Ultraviolet Spectrometer investigation on the Pioneer Venus Orbiter mission was extremely successful. The instrument was designed, built and tested at CU/LASP and delivered on time and within budget. The spacecraft and its instruments were required to operate for 243 days in Venus orbit. OUVS operated successfully for a further 13 years with only minor problems. The major scientific results listed above that deal with Venus were all unexpected and significant discoveries. The Comet Halley observations came about because of a favorable alignment of Halley, the Sun, and Venus, and were an important contribution to the international study of this comet. The scientific results of the OUVS investigation are to be found in the 41 papers listed in section 4 below. OUVS data provided material for 6 PhD and one MS dissertations, listed in section 5 below.

  19. Mars orbiter laser altimeter: receiver model and performance analysis.

    PubMed

    Abshire, J B; Sun, X; Afzal, R S

    2000-05-20

    The design, calibration, and performance of the Mars Orbiter Laser Altimeter (MOLA) receiver are described. The MOLA measurements include the range to the surface, which is determined by the laser-pulse time of flight; the height variability within the footprint determined by the laser echo pulse width; and the apparent surface reflectivity determined by the ratio of the echo to transmitted pulse energies. PMID:18345159

  20. Cryogenic thermal system analysis for orbital propellant depot

    NASA Astrophysics Data System (ADS)

    Chai, Patrick R.; Wilhite, Alan W.

    2014-09-01

    In any manned mission architecture, upwards of seventy percent of all payload delivered to orbit is propellant, and propellant mass fraction dominates almost all transportation segments of any mission requiring a heavy lift launch system like the Saturn V. To mitigate this, the use of an orbital propellant depot has been extensively studied. In this paper, a thermal model of an orbital propellant depot is used to examine the effects of passive and active thermal management strategies. Results show that an all passive thermal management strategy results in significant boil-off for both hydrogen and oxygen. At current launch vehicle prices, these boil-offs equate to millions of dollars lost per month. Zero boil-off of propellant is achievable with the use of active cryocoolers; however, the cooling power required to produce zero-boil-off is an order of magnitude higher than current state-of-the-art cryocoolers. This study shows a zero-boil-off cryocooler minimum power requirement of 80-100 W at 80 K for liquid oxygen, and 100-120 W at 20 K for liquid hydrogen for a representative Near-Earth Object mission. Research and development effort is required to improve the state-of-the-arts in-space cryogenic thermal management.

  1. Unsteady aerodynamic flow field analysis of the space shuttle configuration. Part 4: 747/orbiter aeroelastic stability

    NASA Technical Reports Server (NTRS)

    Reding, J. P.; Ericsson, L. E.

    1976-01-01

    A quasi-steady analysis of the aeroelastic stability of the lateral (antisymmetric) modes of the 747/orbiter vehicle was accomplished. The interference effect of the orbiter wake on the 747 tail furnishes an aerodynamic undamping contribution to the elastic modes. Likewise, the upstream influence of the 747 tail and aft fuselage on the orbiter beaver-tail rail fairing also is undamping. Fortunately these undamping effects cannot overpower the large damping contribution of the 747 tail and the modes are damped for the configurations analyzed. However, significant interference effects of the orbiter on the 747 tail have been observed in the pitch plane. The high response of the 747 vertical tail in the orbiter wave was also considered. Wind tunnel data points to flapping of the OMS pod wakes as the source of the wake resonance phenomenon.

  2. Lunar Impact Basins: Stratigraphy, Sequence and Ages from Superposed Impact Crater Populations Measured from Lunar Orbiter Laser Altimeter (LOLA) Data

    NASA Technical Reports Server (NTRS)

    Fassett, C. I.; Head, J. W.; Kadish, S. J.; Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2012-01-01

    Impact basin formation is a fundamental process in the evolution of the Moon and records the history of impactors in the early solar system. In order to assess the stratigraphy, sequence, and ages of impact basins and the impactor population as a function of time, we have used topography from the Lunar Orbiter Laser Altimeter (LOLA) on the Lunar Reconnaissance Orbiter (LRO) to measure the superposed impact crater size-frequency distributions for 30 lunar basins (D = 300 km). These data generally support the widely used Wilhelms sequence of lunar basins, although we find significantly higher densities of superposed craters on many lunar basins than derived by Wilhelms (50% higher densities). Our data also provide new insight into the timing of the transition between distinct crater populations characteristic of ancient and young lunar terrains. The transition from a lunar impact flux dominated by Population 1 to Population 2 occurred before the mid-Nectarian. This is before the end of the period of rapid cratering, and potentially before the end of the hypothesized Late Heavy Bombardment. LOLA-derived crater densities also suggest that many Pre-Nectarian basins, such as South Pole-Aitken, have been cratered to saturation equilibrium. Finally, both crater counts and stratigraphic observations based on LOLA data are applicable to specific basin stratigraphic problems of interest; for example, using these data, we suggest that Serenitatis is older than Nectaris, and Humboldtianum is younger than Crisium. Sample return missions to specific basins can anchor these measurements to a Pre-Imbrian absolute chronology.

  3. Challenges in assignment of orbital populations in a high spin manganese(iii) complex.

    PubMed

    Fitzpatrick, A J; Stepanovic, S; Müller-Bunz, H; Gruden-Pavlović, M A; García-Fernández, P; Morgan, G G

    2016-04-12

    Magnetic, structural and computational data of four complex salts with the same mononuclear high spin octahedral Mn(iii) complex cation are reported. The manifestation of Jahn-Teller-like distortions in the Mn(iii) cation is dependent on the nature of the charge-balancing anion, with small anions yielding a planar elongation and large anions freezing out a preferential axial elongation along one of the amine-Mn-imine directions within that same plane. Modulation of the lattice by changing the charge balancing anion results in mixing of the orbital symmetry due to vibrational perturbation. PMID:26974518

  4. Body composition analysis in the pediatric population.

    PubMed

    Weber, David R; Leonard, Mary B; Zemel, Babette S

    2012-11-01

    Body composition analysis has become a useful tool in both clinical and research settings. Its use in the pediatric population is complicated by the rapid periods of growth and physical development that are characteristic of infancy, childhood, and adolescence. A thorough understanding of the changing nature of body composition during this time is essential for choosing the most appropriate measurement technique for a given individual, population, or clinical question. Growing evidence suggests that tissues such as fat, muscle, and bone are intimately involved in the regulation of whole body energy metabolism. This knowledge, when coupled with advancements in imaging techniques such as MRI and PET-CT, offers the possibility of developing new models of "functional" body composition. These models may prove to be especially important when assessing malnutrition and metabolic risk in patients with chronic disease. PMID:23469390

  5. On protection of Freedom's solar dynamic radiator from the orbital debris environment. I - Preliminary analysis and testing

    NASA Technical Reports Server (NTRS)

    Rhatigan, Jennifer L.; Christiansen, Eric L.; Fleming, Michael L.

    1992-01-01

    A great deal of experimentation and analysis was performed to quantify penetration thresholds of components which will experience orbital debris impacts. Penetration was found to depend upon mission specific parameters such as orbital altitude, inclination, and orientation of the component; and upon component specific parameters such as material, density and the geometry particular to its shielding. Experimental results are highly dependent upon shield configuration and cannot be extrapolated with confidence to alternate shield configurations. Also, current experimental capabilities are limited to velocities which only approach the lower limit of predicted orbital debris velocities. Therefore, prediction of the penetrating particle size for a particular component having a complex geometry remains highly uncertain. An approach is described which was developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses are presented to quantify the solar dynamic radiator survivability, and include the type of particle and particle population expected to defeat the radiator bumpering (i.e., penetrate a fluid flow tube). Results of preliminary hypervelocity impact testing performed on radiator panel samples (in the 6 to 7 km/sec velocity range) are also presented.

  6. Preliminary orbital analysis of the LARES space experiment

    NASA Astrophysics Data System (ADS)

    Ciufolini, Ignazio; Paolozzi, Antonio; Pavlis, Erricos C.; Koenig, Rolf; Ries, John; Gurzadyan, Vahe; Matzner, Richard; Penrose, Roger; Sindoni, Giampiero; Paris, Claudio

    2015-07-01

    The LARES satellite was successfully launched in 2012 for tests of General Relativity and gravitational physics including the accurate measurement of frame-dragging. It is currently very well observed all over the world by the stations of the International Laser Ranging Service. Its preliminary orbital analyses show that LARES behaves as the best artificial massive test particle today available in the solar system, providing an optimal approximation to the time-like geodesic motion of General Relativity. Furthermore, on the basis of a test using almost three years of observations of LARES, we concluded that LARES, together with the LAGEOS and LAGEOS 2 satellites, provides excellent preliminary results for testing General Relativity.

  7. Study of geopotential error models used in orbit determination error analysis

    NASA Technical Reports Server (NTRS)

    Yee, C.; Kelbel, D.; Lee, T.; Samii, M. V.; Mistretta, G. D.; Hart, R. C.

    1991-01-01

    The uncertainty in the geopotential model is currently one of the major error sources in the orbit determination of low-altitude Earth-orbiting spacecraft. The results of an investigation of different geopotential error models and modeling approaches currently used for operational orbit error analysis support at the Goddard Space Flight Center (GSFC) are presented, with emphasis placed on sequential orbit error analysis using a Kalman filtering algorithm. Several geopotential models, known as the Goddard Earth Models (GEMs), were developed and used at GSFC for orbit determination. The errors in the geopotential models arise from the truncation errors that result from the omission of higher order terms (omission errors) and the errors in the spherical harmonic coefficients themselves (commission errors). At GSFC, two error modeling approaches were operationally used to analyze the effects of geopotential uncertainties on the accuracy of spacecraft orbit determination - the lumped error modeling and uncorrelated error modeling. The lumped error modeling approach computes the orbit determination errors on the basis of either the calibrated standard deviations of a geopotential model's coefficients or the weighted difference between two independently derived geopotential models. The uncorrelated error modeling approach treats the errors in the individual spherical harmonic components as uncorrelated error sources and computes the aggregate effect using a combination of individual coefficient effects. This study assesses the reasonableness of the two error modeling approaches in terms of global error distribution characteristics and orbit error analysis results. Specifically, this study presents the global distribution of geopotential acceleration errors for several gravity error models and assesses the orbit determination errors resulting from these error models for three types of spacecraft - the Gamma Ray Observatory, the Ocean Topography Experiment, and the Cosmic

  8. Utility of histogram analysis of ADC maps for differentiating orbital tumors

    PubMed Central

    Xu, Xiao-Quan; Hu, Hao; Su, Guo-Yi; Liu, Hu; Hong, Xun-Ning; Shi, Hai-Bin; Wu, Fei-Yun

    2016-01-01

    PURPOSE We aimed to evaluate the role of histogram analysis of apparent diffusion coefficient (ADC) maps for differentiating benign and malignant orbital tumors. METHODS Fifty-two patients with orbital tumors were enrolled from March 2013 to November 2014. Pretreatment diffusion-weighted imaging was performed on a 3T magnetic resonance scanner with b factors of 0 and 800 s/mm2, and the corresponding ADC maps were generated. Whole-tumor regions of interest were drawn on all slices of the ADC maps to obtain histogram parameters, including ADCmean, ADCmedian, standard deviation (SD), skewness, kurtosis, quartile, ADC10, ADC25, ADC75, and ADC90. Histogram parameter differences between benign and malignant orbital tumors were compared. The diagnostic value of each significant parameter in predicting malignant tumors was established. RESULTS Age, ADCmean, ADCmedian, quartile, kurtosis, ADC10, ADC25, ADC75, and ADC90 parameters were significantly different between benign and malignant orbital tumor groups, while gender, location, SD, and skewness were not significantly different. The best diagnostic performance in predicting malignant orbital tumors was achieved at the threshold of ADC10=0.990 (AUC, 0.997; sensitivity, 96.2%; specificity, 100%). CONCLUSION Histogram analysis of ADC maps holds promise for differentiating benign and malignant orbital tumors. ADC10 has the potential to be the most significant parameter for predicting malignant orbital tumors. PMID:26829400

  9. A Monte Carlo error analysis program for near-Mars, finite-burn, orbital transfer maneuvers

    NASA Technical Reports Server (NTRS)

    Green, R. N.; Hoffman, L. H.; Young, G. R.

    1972-01-01

    A computer program was developed which performs an error analysis of a minimum-fuel, finite-thrust, transfer maneuver between two Keplerian orbits in the vicinity of Mars. The method of analysis is the Monte Carlo approach where each off-nominal initial orbit is targeted to the desired final orbit. The errors in the initial orbit are described by two covariance matrices of state deviations and tracking errors. The function of the program is to relate these errors to the resulting errors in the final orbit. The equations of motion for the transfer trajectory are those of a spacecraft maneuvering with constant thrust and mass-flow rate in the neighborhood of a single body. The thrust vector is allowed to rotate in a plane with a constant pitch rate. The transfer trajectory is characterized by six control parameters and the final orbit is defined, or partially defined, by the desired target parameters. The program is applicable to the deboost maneuver (hyperbola to ellipse), orbital trim maneuver (ellipse to ellipse), fly-by maneuver (hyperbola to hyperbola), escape maneuvers (ellipse to hyperbola), and deorbit maneuver.

  10. Experimental and Computational Analysis of Shuttle Orbiter Hypersonic Trim Anomaly

    NASA Technical Reports Server (NTRS)

    Brauckmann, Gregory J.; Paulson, John W., Jr.; Weilmuenster, K. James

    1995-01-01

    During the high-Mach-number, high-altitude portion of the first entry of the Shuttle Orbiter, the vehicle exhibited a nose-up pitching moment relative to preflight prediction of approximately Delta Cm = 0.03. This trim anomaly has been postulated to be due to compressibility, viscous, and/or real-gas (lowered specific heat ratio gamma) effects on basic body pitching moment, body-flap effectiveness, or both. In order to assess the relative contribution of each of these effects, an experimental study was undertaken to examine the effects of Mach number, Reynolds number, and ratio of specific heats. Complementary computational solutions were obtained for wind-tunnel and flight conditions. The primary cause of the anomaly was determined to be lower pressures on the aft windward surface of the Orbiter than deduced from hypersonic wind-tunnel tests with ideal- or near-ideal-gas test flow. The lower pressure levels are a result of the lowering of the flowfield gamma due to high-temperature effects. This phenomenon was accurately simulated in a hypersonic wind tunnel using a heavy gas, which provided a lower, gamma, and was correctly predicted by Navier-Stokes computations using nonequilibrium chemistry.

  11. An orbital period analysis of the dwarf novae OY Carinae

    NASA Astrophysics Data System (ADS)

    Han, Z.-T.; Qian, S.-B.; Fernández Lajús, E.; Liao, W.-P.; Zhang, J.

    2015-01-01

    By using our twelve new CCD times of light minimum of OY Carinae (OY Car) together with those collected from the literature, it is found that the O-C curve of OY Car shows a downward parabola with an amplitude of 27.8 s and a cyclic change of a period 14.0 yr. The period decrease is opposite to the hypothesis of mass transfer, and it cannot be explained by angular momentum loss via gravitational radiation. The Rappaport et al. (1983)’s magnetic braking (MB) prescription is adopted to explain the observed orbital period decrease. The cyclic change of period is analyzed with the light travel-time effect that originates from gravitational influence of a third body. The mass of the third star is determined to be M3sini‧=0.008097(±0.000014) M⊙=8.48(±0.02) MJup, suggesting that it may be a critical substellar object between brown dwarf and giant planet. If the orbital inclination of the third body equals 90°, the distance between the third body and the mass centre of the whole system is about 6.18(±0.45) AU.

  12. Orbital analysis of the inner Uranian satellites from Hubble images

    NASA Astrophysics Data System (ADS)

    French, Robert S.; Showalter, Mark R.; de Pater, Imke; Lissauer, Jack J.

    2015-11-01

    The thirteen inner moons of Uranus form a densely-packed and possibly chaotic system. Numerical simulations show that several groups of moons exhibit complex resonant interactions, and Mab shows as-yet unexplained variations in its orbit. However, the masses of these moons are currently unknown, limiting the insights that can be gained from numerical simulations. Using over 650 long-exposure images taken during 2003-2013 by the Hubble Space Telescope through broadband filters, we have obtained astrometry for eleven of Uranus’s inner moons, comprising the Portia group (Bianca to Perdita) plus Puck and Mab; attempts to measure the positions of Cordelia and Ophelia are on-going. Using these measurements, which are frequently accurate to 0.05 pixels or less, we have derived Keplerian orbital elements including the influence of Uranus’s oblateness. The elements show year-to-year variations that are statistically significant and indicate the role of mutual perturbations among the moons. We are also using this information to place new constraints on the masses of these moons. We will present our most recent findings.

  13. Population Viability Analysis of Riverine Fishes

    SciTech Connect

    Bates, P.; Chandler, J.; Jager, H.I.; Lepla, K.; Van Winkle, W.

    1999-04-12

    Many utilities face conflkts between two goals: cost-efficient hydropower generation and protecting riverine fishes. Research to develop ecological simulation tools that can evaluate alternative mitigation strategies in terms of their benefits to fish populations is vital to informed decision-making. In this paper, we describe our approach to population viability analysis of riverine fishes in general and Snake River white sturgeon in particular. We are finding that the individual-based modeling approach used in previous in-stream flow applications is well suited to addressing questions about the viability of species of concern for several reasons. Chief among these are: (1) the abiIity to represent the effects of individual variation in life history characteristics on predicted population viabili~, (2) the flexibili~ needed to quanti~ the ecological benefits of alternative flow management options by representing spatial and temporal variation in flow and temperaturty and (3) the flexibility needed to quantifi the ecological benefits of non-flow related manipulations (i.e., passage, screening and hatchery supplementation).

  14. Independent Orbiter Assessment (IOA): Analysis of the Electrical Power Distribution and Control Subsystem, Volume 2

    NASA Technical Reports Server (NTRS)

    Schmeckpeper, K. R.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C) hardware. The EPD and C hardware performs the functions of distributing, sensing, and controlling 28 volt DC power and of inverting, distributing, sensing, and controlling 117 volt 400 Hz AC power to all Orbiter subsystems from the three fuel cells in the Electrical Power Generation (EPG) subsystem. Volume 2 continues the presentation of IOA analysis worksheets and contains the potential critical items list.

  15. Comet Tempel 2: Orbit, ephemerides and error analysis

    NASA Technical Reports Server (NTRS)

    Yeomans, D. K.

    1978-01-01

    The dynamical behavior of comet Tempel 2 is investigated and the comet is found to be very well behaved and easily predictable. The nongravitational forces affecting the motion of this comet are the smallest of any comet that is affected by nongravitational forces. The sign and time history of these nongravitational forces imply (1) a direct rotation of the comet's nucleus and (2) the comet's ability to outgas has not changed substantially over its entire observational history. The well behaved dynamical motion of the comet, the well observed past apparitions, the small nongravitational forces and the excellent 1988 ground based observing conditions all contribute to relatively small position and velocity errors in 1988 -- the year of a proposed rendezvous space mission to this comet. To assist in planned ground based and earth orbital observations of this comet, ephemerides are given for the 1978-79, 1983-84 and 1988 apparitions.

  16. A Preliminary Formation Flying Orbit Dynamics Analysis for Leonardo-BRDF

    NASA Technical Reports Server (NTRS)

    Hughes, Steven P.; Mailhe, Laurie M.

    2001-01-01

    Leonardo-BRDF is a NASA mission concept proposed to allow the investigation of radiative transfer and its effect on the Earth's climate and atmospheric phenomenon. Enabled by the recent developments in small-satellite and formation flying technology, the mission is envisioned to be composed of an array of spacecraft in carefully designed orbits. The different perspectives provided by a distributed array of spacecraft offer a unique advantage to study the Earth's albedo. This paper presents the orbit dynamics analysis performed in the context of the Leonardo-BRDF science requirements. First, the albedo integral is investigated and the effect of viewing geometry on science return is studied. The method used in this paper, based on Gauss quadrature, provides the optimal formation geometry to ensure that the value of the integral is accurately approximated. An orbit design approach is presented to achieve specific relative orbit geometries while simultaneously satisfying orbit dynamics constraints to reduce formation-keeping fuel expenditure. The relative geometry afforded by the design is discussed in terms of mission requirements. An optimal two-burn initialization scheme is presented with the required delta-V to distribute all spacecraft from a common parking orbit into their appropriate orbits in the formation. Finally, formation-keeping strategies are developed and the associated delta-V's are calculated to maintain the formation in the presence of perturbations.

  17. Orbit Determination Using SLR Data for STSAT-2C: Short-arc Analysis

    NASA Astrophysics Data System (ADS)

    Kim, Young-Rok; Park, Eunseo; Kucharski, Daniel; Lim, Hyung-Chul

    2015-09-01

    In this study, we present the results of orbit determination (OD) using satellite laser ranging (SLR) data for the Science and Technology Satellite (STSAT)-2C by a short-arc analysis. For SLR data processing, the NASA/GSFC GEODYN II software with one year (2013/04 - 2014/04) of normal point observations is used. As there is only an extremely small quantity of SLR observations of STSAT-2C and they are sparsely distribution, the selection of the arc length and the estimation intervals for the atmospheric drag coefficients and the empirical acceleration parameters was made on an arc-to-arc basis. For orbit quality assessment, the post-fit residuals of each short-arc and orbit overlaps of arcs are investigated. The OD results show that the weighted root mean square post-fit residuals of short-arcs are less than 1 cm, and the average 1-day orbit overlaps are superior to 50/600/900 m for the radial/cross-track/along-track components. These results demonstrate that OD for STSAT-2C was successfully achieved with cm-level range precision. However its orbit quality did not reach the same level due to the availability of few and sparse measurement conditions. From a mission analysis viewpoint, obtaining the results of OD for STSAT-2C is significant for generating enhanced orbit predictions for more frequent tracking.

  18. Unsteady aerodynamic flow field analysis of the space shuttle configuration. Part 1: Orbiter aerodynamics

    NASA Technical Reports Server (NTRS)

    Ericsson, L. E.; Reding, J. P.

    1976-01-01

    An analysis of the steady and unsteady aerodynamics of the space shuttle orbiter has been performed. It is shown that slender wing theory can be modified to account for the effect of Mach number and leading edge roundness on both attached and separated flow loads. The orbiter unsteady aerodynamics can be computed by defining two equivalent slender wings, one for attached flow loads and another for the vortex-induced loads. It is found that the orbiter is in the transonic speed region subject to vortex-shock-boundary layer interactions that cause highly nonlinear or discontinuous load changes which can endanger the structural integrity of the orbiter wing and possibly cause snap roll problems. It is presently impossible to simulate these interactions in a wind tunnel test even in the static case. Thus, a well planned combined analytic and experimental approach is needed to solve the problem.

  19. Orbit Processing and Analysis of a GEO Class of High Area-to-Mass Debris Objects

    NASA Technical Reports Server (NTRS)

    Kelecy, Tom; Payne, Tim; Thurston, Robin; Stansbery, Gene

    2007-01-01

    A population of recently discovered deep space objects is thought to be debris having origins from sources in the geosynchronous orbit (GEO) belt. Observations have been presented indicating that these objects have area-to-mass ratios (AMR's) of anywhere from 1's to 10's of m(exp 2)/kg, and thus would explain the observed migration of eccentricity (0.1-0.6) and inclination that distinguishes their orbital characteristics. The solar radiation perturbations on orbital period, inclination and eccentricity over a 20 year period for AMR's of 0.01, 1, 10 and 20 m(exp 2)/kg, are shown in the figures. There is a heightened interest in the international community due to the large number and small size of these objects, as they pose a hazard to active satellites operating in the vicinity of the GEO belt.

  20. TSS tether cable meteoroid/orbital debris damage analysis

    NASA Technical Reports Server (NTRS)

    Hayashida, K. B.; Robinson, J. H.

    1993-01-01

    This report summarizes the damage analyses performed on the tether cable used for the tethered satellite system (TSS), for the damage that could be caused by meteoroid or orbital debris impacts. The TSS consists of a tethered satellite deployer and a tethered satellite. The analytical studies were performed at Marshall Space Flight Center (MSFC) with the results from the following tests: (1) hypervelocity impact tests to determine the 'critical' meteoroid particle diameter, i.e., the maximum size of a meteoroid particle which can impact the tether cable without causing 'failure'; (2) electrical resistance tests on the damaged and undamaged tether cable to determine if degradation of current flow occurred through the damaged tether cables; and (3) tensile load tests to verify the load carrying capability of the damaged tether cables. Finally, the HULL hydrodynamic computer code was used to simulate the hypervelocity impact of the tether cable by particles at velocities higher than can be tested, to determine the extent of the expected tether damage.

  1. A photometric and orbital analysis of GT MUSCAE

    NASA Astrophysics Data System (ADS)

    Murdoch, K. A.; Hearnshaw, J. B.; Kilmartin, P. M.; Gilmore, A. C.

    1995-10-01

    GT Mus is a quadruple system comprising a long-period RS CVn-type binary (HD 101379) and a pair of eclipsing A dwarfs (HD 101380). Six and a half years of UBV (RI)_C photometry obtained at the Mt John University Observatory has enabled identification of four distinct types of photometric variability in this system. These are (1) a slowly changing mean magnitude, which probably arises from an activity-cycle-like effect in the active component of HD 101379, (2) a periodic variation (P_rot~64d), which is attributed to rotational modulation due to spots on the active star, (3) a periodic variation (P_eclipse=2.7546d) due to the eclipses of HD 101380, and (4) an excess in the I band, which occurs on a short time-scale (<1d) and is probably associated with HD 101379 activity. The evolution of the light curve of HD 101379 is fast with respect to the rotational period, suggesting rapid spot evolution for which we anticipate a possible model. The colours of HD 101379, even at maximum brightness, are excessively red for its spectral type, unless there is significant reddening by dust. Radial velocity measurements of HD 101379 are also presented, along with an improved determination of the orbit of this somewhat long-period (P_orb=61.448d) system.

  2. Orbit on demand - Structural analysis finds vertical launchers weigh less

    NASA Technical Reports Server (NTRS)

    Taylor, A. H.; Cruz, C. I.; Jackson, L. R.; Naftel, J. C.; Wurster, K. E.; Cerro, J. A.

    1985-01-01

    Structural considerations arising from favored design concepts for the next generation on-demand launch vehicles are explored. The two emerging concepts are a two stage fully reusable vertical take-off vehicle (V-2) and a horizontal take-off, two stage subsonic boost launch vehicle (H-2-Sub). Both designs have an 1100 n. mi. cross-range capability, with the V-2 orbiter having small wings with winglets for hypersonic trim and the H-2-Sub requiring larger, swept wings. The rockets would be cryogenic, while airbreathing initial boosters would be either turbofans, turbojets and/or ramjets. Dynamic loading is lower in the launch of a V-2. The TPS is a critical factor due to thinner leading edges than on the Shuttle and may require heat-pipe cooling. Airframe structures made of metal matrix composites have passed finite element simulations of projected loads and can now undergo proof-of-concept tests, although whisker-reinforced materials may be superior once long-whisker technology is developed.

  3. Dynamical analysis of an orbiting three-rigid-body system

    SciTech Connect

    Pagnozzi, Daniele E-mail: james.biggs@strath.ac.uk; Biggs, James D. E-mail: james.biggs@strath.ac.uk

    2014-12-10

    The development of multi-joint-spacecraft mission concepts calls for a deeper understanding of their nonlinear dynamics to inform and enhance system design. This paper presents a study of a three-finite-shape rigid-body system under the action of an ideal central gravitational field. The aim of this paper is to gain an insight into the natural dynamics of this system. The Hamiltonian dynamics is derived and used to identify relative attitude equilibria of the system with respect to the orbital reference frame. Then a numerical investigation of the behaviour far from the equilibria is provided using tools from modern dynamical systems theory such as energy methods, phase portraits and Poincarè maps. Results reveal a complex structure of the dynamics as well as the existence of connections between some of the equilibria. Stable equilibrium configurations appear to be surrounded by very narrow regions of regular and quasi-regular motions. Trajectories evolve on chaotic motions in the rest of the domain.

  4. Evaluation and analysis of the orbital maneuvering vehicle video system

    NASA Technical Reports Server (NTRS)

    Moorhead, Robert J., II

    1989-01-01

    The work accomplished in the summer of 1989 in association with the NASA/ASEE Summer Faculty Research Fellowship Program at Marshall Space Flight Center is summarized. The task involved study of the Orbital Maneuvering Vehicle (OMV) Video Compression Scheme. This included such activities as reviewing the expected scenes to be compressed by the flight vehicle, learning the error characteristics of the communication channel, monitoring the CLASS tests, and assisting in development of test procedures and interface hardware for the bit error rate lab being developed at MSFC to test the VCU/VRU. Numerous comments and suggestions were made during the course of the fellowship period regarding the design and testing of the OMV Video System. Unfortunately from a technical point of view, the program appears at this point in time to be trouble from an expense prospective and is in fact in danger of being scaled back, if not cancelled altogether. This makes technical improvements prohibitive and cost-reduction measures necessary. Fortunately some cost-reduction possibilities and some significant technical improvements that should cost very little were identified.

  5. Spatial Analysis of Galactic Cosmic Ray Particles in Low Earth Orbit/Near Equator Orbit Using SPENVIS

    NASA Astrophysics Data System (ADS)

    Suparta, W.; Zulkeple, S. K.

    2014-04-01

    The space environment has grown intensively harmful to spacecraft and astronauts. Galactic cosmic rays (GCRs) are one of the radiation sources that composed of high energetic particles originated from space and capable of damaging electronic systems through single event upset (SEU) process. In this paper, we analyzed GCR fluxes at different altitudes by using Space Environment Information System (SPENVIS) software and the results are compared to determine their intensities with respect to distance in the Earth's orbit. The altitudes are set at low earth orbit (400 km and 685 km), medium earth orbit (19,100 km and 20,200 km) and high earth orbit (35,793 km and 1,000,000 km). Then, within Low Earth Orbit (LEO) near the equator (NEqO), we used altitude of 685 km to compare GCRs with the intensities of solar particles and trapped particles in the radiation belt to determine the significance of GCRs in the orbit itself.

  6. Objectives for Mars Orbital Missions in the 2020s: Report from a MEPAG Science Analysis Group

    NASA Astrophysics Data System (ADS)

    Zurek, R. W.; Campbell, B. A.; Diniega, S.; Lock, R. E.

    2015-12-01

    NASA Headquarters is looking at possible missions to Mars to follow the proposed 2020 Mars rover mission currently in development. One option being considered is a multi-functional orbiter, launched in the early 2020's, whose capabilities could address objectives in the following areas: • Replenishment of the telecommunications and reconnaissance infrastructure presently provided by the aging Mars Odyssey and Mars Reconnaissance Orbiters; • Scientific and technical progress on the NRC Planetary Science Decadal Survey priorities, updated MEPAG Goals, and/or follow-up of new discoveries; • Location and quantification of in situ resources for utilization by future robotic and human surface-based missions; and • Data needed to address Strategic Knowledge Gaps (SKGs), again for possible human missions. The Mars Exploration Program Analysis Group (MEPAG) was asked to prepare an analysis of possible science objectives and remote sensing capabilities that could be implemented by such a multi-purpose Mars orbiter launched in the 2022/24 timeframe. MEPAG conducted this analysis through formation of a Next Orbiter Science Analysis Group (NEX-SAG), which was chartered jointly by the NASA Science and Human Exploration Directorates. The SAG was asked to conduct this study within a range of mission capabilities, including the possible first use of Solar Electric Propulsion (SEP) in the Mars system. SEP could provide additional power enabling new payload components and possible changes in orbit (e.g., orbital inclination change) that permit different mission observational campaigns (e.g., polar and non-polar). Special attention was paid towards identifying synergies between science investigations, reconnaissance, and resource/SKG needs. We will present the findings and conclusions of this NEX-SAG regarding possible objectives for the next NASA Orbiter to Mars.

  7. Independent Orbiter Assessment (IOA): Analysis of the reaction control system, volume 1

    NASA Technical Reports Server (NTRS)

    Burkemper, V. J.; Haufler, W. A.; Odonnell, R. A.; Paul, D. J.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results for the Reaction Control System (RCS). The purpose of the RCS is to provide thrust in and about the X, Y, Z axes for External Tank (ET) separation; orbit insertion maneuvers; orbit translation maneuvers; on-orbit attitude control; rendezvous; proximity operations (payload deploy and capture); deorbit maneuvers; and abort attitude control. The RCS is situated in three independent modules, one forward in the orbiter nose and one in each OMS/RCS pod. Each RCS module consists of the following subsystems: Helium Pressurization Subsystem; Propellant Storage and Distribution Subsystem; Thruster Subsystem; and Electrical Power Distribution and Control Subsystem. Of the failure modes analyzed, 307 could potentially result in a loss of life and/or loss of vehicle.

  8. An automated data management/analysis system for space shuttle orbiter tiles. [stress analysis

    NASA Technical Reports Server (NTRS)

    Giles, G. L.; Ballas, M.

    1982-01-01

    An engineering data management system was combined with a nonlinear stress analysis program to provide a capability for analyzing a large number of tiles on the space shuttle orbiter. Tile geometry data and all data necessary of define the tile loads environment accessed automatically as needed for the analysis of a particular tile or a set of tiles. User documentation provided includes: (1) description of computer programs and data files contained in the system; (2) definitions of all engineering data stored in the data base; (3) characteristics of the tile anaytical model; (4) instructions for preparation of user input; and (5) a sample problem to illustrate use of the system. Description of data, computer programs, and analytical models of the tile are sufficiently detailed to guide extension of the system to include additional zones of tiles and/or additional types of analyses

  9. A Ballistic Limit Analysis Program for Shielding Against Micrometeoroids and Orbital Debris

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon; Christiansen, Erie

    2010-01-01

    A software program has been developed that enables the user to quickly and simply perform ballistic limit calculations for common spacecraft structures that are subject to hypervelocity impact of micrometeoroid and orbital debris (MMOD) projectiles. This analysis program consists of two core modules: design, and; performance. The design module enables a user to calculate preliminary dimensions of a shield configuration (e.g., thicknesses/areal densities, spacing, etc.) for a ?design? particle (diameter, density, impact velocity, incidence). The performance module enables a more detailed shielding analysis, providing the performance of a user-defined shielding configuration over the range of relevant in-orbit impact conditions.

  10. Orbiter Trajectory Analysis for a Two-Stage Reusable Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Cowling, Adam L.

    2011-01-01

    Trajectory analysis performed on NASA's reference two-stage-to-orbit launch vehicle upper stage will be presented. The work was completed in support of the Hypersonics Multidisciplinary Analysis and Optimization effort for the NASA-Air Force Joint System Study. Three degree-of-freedom (3-DOF) untrimmed trajectory analysis was performed for the orbiter ascent, closure and re-entry. An iterative closure process resulted in a 333,000 lb initial mass for the orbiter. The re-entry trajectory satisfied heating constraints for all payload out cases and met the constraints with reduced margins for payload in cases. Abort trajectories for engine out at staging, engine out during ascent, and failure to circularize in orbit, gave insight to the robustness of the orbiter. A trimmed ascent trajectory defined an engine gimbal location and the body flap angle best suited for maximizing injected mass. A trimmed re-entry trajectory revealed a need to update the trim routine to accommodate full flap aerodynamic data.

  11. Power Extension Package (PEP) system definition extension, orbital service module systems analysis study. Volume 3: PEP analysis and tradeoffs

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The objectives, conclusions, and approaches for accomplishing 19 specific design and analysis activities related to the installation of the power extension package (PEP) into the Orbiter cargo bay are described as well as those related to its deployment, extension, and retraction. The proposed cable handling system designed to transmit power from PEP to the Orbiter by way of the shuttle remote manipulator system is described and a preliminary specification for the gimbal assembly, solar array drive is included.

  12. Microsatellite analysis of genetic diversity and population structure of Arabian horse populations.

    PubMed

    Khanshour, Anas; Conant, Eleanore; Juras, Rytis; Cothran, Ernest Gus

    2013-01-01

    The Arabian horse ignites imagination throughout the world. Populations of this breed exist in many countries, and recent genetic work has examined the diversity and ancestry of a few of these populations in isolation. Here, we explore 7 different populations of Arabians represented by 682 horses. Three of these are Middle Eastern populations from near the historical origin of the breed, including Syrian, Persian, and Saudi Arabian. The remaining Western populations are found in Europe (the Shagya Arabian and Polish Arabian) and in America (American Arabian). Analysis of genetic structure was carried out using 15 microsatellite loci. Genetic distances, analysis of molecular variance, factorial correspondence analysis, and a Bayesian method were applied. The results consistently show higher level of diversity within the Middle Eastern populations than the Western populations. The Western Arabian populations were the main source among population variation. Genetic differentiation was not strong among all Middle Eastern populations, but all American Arabians showed differentiation from Middle Eastern populations and were somewhat uniform among themselves. Here, we explore the diversities of many different populations of Arabian horses and find that populations not from the Middle East have noticeably lower levels of diversity, which may adversely affect the health of these populations. PMID:23450090

  13. Space Trajectory Error Analysis Program (STEAP) for halo orbit missions. Volume 2: Programmer's manual

    NASA Technical Reports Server (NTRS)

    Byrnes, D. V.; Carney, P. C.; Underwood, J. W.; Vogt, E. D.

    1974-01-01

    The six month effort was responsible for the development, test, conversion, and documentation of computer software for the mission analysis of missions to halo orbits about libration points in the earth-sun system. The software consisting of two programs called NOMNAL and ERRAN is part of the Space Trajectories Error Analysis Programs. The program NOMNAL targets a transfer trajectory from earth on a given launch date to a specified halo orbit on a required arrival date. Either impulsive or finite thrust insertion maneuvers into halo orbit are permitted by the program. The transfer trajectory is consistent with a realistic launch profile input by the user. The second program ERRAN conducts error analyses of the targeted transfer trajectory. Measurements including range, doppler, star-planet angles, and apparent planet diameter are processed in a Kalman-Schmidt filter to determine the trajectory knowledge uncertainty.

  14. Analysis, design, and test of a graphite/polyimide Shuttle orbiter body flap segment

    NASA Technical Reports Server (NTRS)

    Graves, S. R.; Morita, W. H.

    1982-01-01

    For future missions, increases in Space Shuttle orbiter deliverable and recoverable payload weight capability may be needed. Such increases could be obtained by reducing the inert weight of the Shuttle. The application of advanced composites in orbiter structural components would make it possible to achieve such reductions. In 1975, NASA selected the orbiter body flap as a demonstration component for the Composite for Advanced Space Transportation Systems (CASTS) program. The progress made in 1977 through 1980 was integrated into a design of a graphite/polyimide (Gr/Pi) body flap technology demonstration segment (TDS). Aspects of composite body flap design and analysis are discussed, taking into account the direct-bond fibrous refractory composite insulation (FRCI) tile on Gr/Pi structure, Gr/Pi body flap weight savings, the body flap design concept, and composite body flap analysis. Details regarding the Gr/Pi technology demonstration segment are also examined.

  15. Thermal and orbital analysis of Earth monitoring Sun-synchronous space experiments

    NASA Technical Reports Server (NTRS)

    Killough, Brian D.

    1990-01-01

    The fundamentals of an Earth monitoring Sun-synchronous orbit are presented. A Sun-synchronous Orbit Analysis Program (SOAP) was developed to calculate orbital parameters for an entire year. The output from this program provides the required input data for the TRASYS thermal radiation computer code, which in turn computes the infrared, solar and Earth albedo heat fluxes incident on a space experiment. Direct incident heat fluxes can be used as input to a generalized thermal analyzer program to size radiators and predict instrument operating temperatures. The SOAP computer code and its application to the thermal analysis methodology presented, should prove useful to the thermal engineer during the design phases of Earth monitoring Sun-synchronous space experiments.

  16. Time series analysis of electron flux at geostationary orbit

    SciTech Connect

    Szita, S.; Rodgers, D.J.; Johnstone, A.D.

    1996-07-01

    Time series of energetic (42.9{endash}300 keV) electron flux data from the geostationary satellite Meteosat-3 shows variability over various timescales. Of particular interest are the strong local time dependence of the flux data and the large flux peaks associated with particle injection events which occur over a timescale of a few hours. Fourier analysis has shown that for this energy range, the average electron flux diurnal variation can be approximated by a combination of two sine waves with periods of 12 and 24 hours. The data have been further examined using wavelet analysis, which shows how the diurnal variation changes and where it appears most significant. The injection events have a characteristic appearance but do not occur in phase with one another and therefore do not show up in a Fourier spectrum. Wavelet analysis has been used to look for characteristic time scales for these events. {copyright} {ital 1996 American Institute of Physics.}

  17. Failure Analysis of Space Shuttle Orbiter Valve Poppet

    NASA Technical Reports Server (NTRS)

    Russell, Rick

    2010-01-01

    The poppet failed during STS-126 due to fatigue cracking that most likely was initiated during MDC ground-testing. This failure ultimately led to the discovery that the cracking problem was a generic issue effecting numerous poppets throughout the Shuttle program's history. This presentation has focused on the laboratory analysis of the failed hardware, but this analysis was only one aspect of a comprehensive failure investigation. One critical aspect of the overall investigation was modeling of the fluid flow through this valve to determine the possible sources of cyclic loading. This work has led to the conclusion that the poppets are failing due to flow-induced vibration.

  18. 3D-Assisted Quantitative Assessment of Orbital Volume Using an Open-Source Software Platform in a Taiwanese Population

    PubMed Central

    Shyu, Victor Bong-Hang; Hsu, Chung-En; Chen, Chih-hao; Chen, Chien-Tzung

    2015-01-01

    Orbital volume evaluation is an important part of pre-operative assessments in orbital trauma and congenital deformity patients. The availability of the affordable, open-source software, OsiriX, as a tool for preoperative planning increased the popularity of radiological assessments by the surgeon. A volume calculation method based on 3D volume rendering-assisted region-of-interest computation was used to determine the normal orbital volume in Taiwanese patients after reorientation to the Frankfurt plane. Method one utilized 3D points for intuitive orbital rim outlining. The mean normal orbital volume for left and right orbits was 24.3±1.51 ml and 24.7±1.17 ml in male and 21.0±1.21 ml and 21.1±1.30 ml in female subjects. Another method (method two) based on the bilateral orbital lateral rim was also used to calculate orbital volume and compared with method one. The mean normal orbital volume for left and right orbits was 19.0±1.68 ml and 19.1±1.45 ml in male and 16.0±1.01 ml and 16.1±0.92 ml in female subjects. The inter-rater reliability and intra-rater measurement accuracy between users for both methods was found to be acceptable for orbital volume calculations. 3D-assisted quantification of orbital volume is a feasible technique for orbital volume assessment. The normal orbital volume can be used as controls in cases of unilateral orbital reconstruction with a mean size discrepancy of less than 3.1±2.03% in females and 2.7±1.32% in males. The OsiriX software can be used reliably by the individual surgeon as a comprehensive preoperative planning and imaging tool for orbital volume measurement and computed tomography reorientation. PMID:25774683

  19. Pioneer Mars surface penetrator mission. Mission analysis and orbiter design

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The Mars Surface Penetrator mission was designed to provide a capability for multiple and diverse subsurface science measurements at a low cost. Equipment required to adapt the Pioneer Venus spacecraft for the Mars mission is described showing minor modifications to hardware. Analysis and design topics which are similar and/or identical to the Pioneer Venus program are briefly discussed.

  20. Orbital Injection of the SEDSAT Satellite: Tethered Systems Dynamics and Flight Data Analysis

    NASA Technical Reports Server (NTRS)

    Lorenzini, Enrico C.; Gullahorn, Gordon E.; Cosmo, Mario L.; Ruiz, Manuel; Pelaez, Jesus

    1996-01-01

    This report deals with the following topics which are all related to the orbital injection of the SEDSAT satellite: Dynamics and Stability of Tether Oscillations after the First Cut. The dynamics of the tether after the first cut (i.e., without the Shuttle attached to it) is investigated. The tether oscillations with the free end are analyzed in order to assess the stability of the rectilinear configuration in between the two tether cuts; analysis of Unstable Modes. The unstable modes that appear for high libration angles are further investigated in order to determine their occurrences and the possible transition from bound librations to rotations; Orbital Release Strategies for SEDSAT. A parametric analysis of the orbital decay rate of the SEDSAT satellite after the two tether cuts has been carried out as a function of the following free parameters: libration amplitude at the end of deployment, deviation angle from LV at the first cut, and orbital anomaly at the second cut. The values of these parameters that provide a minimum orbital decay rate of the satellite (after the two cuts) have been computed; and Dynamics and Control of SEDSAT. The deployment control law has been modified to cope with the new ejection velocity of the satellite from the Shuttle cargo bay. New reference profiles have been derived as well as new control parameters. Timing errors at the satellite release as a function of the variations of the initial conditions and the tension model parameters have been estimated for the modified control law.

  1. Independent Orbiter Assessment (IOA): Analysis of the communication and tracking subsystem

    NASA Technical Reports Server (NTRS)

    Gardner, J. R.; Robinson, W. M.; Trahan, W. H.; Daley, E. S.; Long, W. C.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Communication and Tracking hardware. The IOA analysis process utilized available Communication and Tracking hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  2. Automated Analysis of a Diverse Synapse Population

    PubMed Central

    Busse, Brad; Smith, Stephen

    2013-01-01

    Synapses of the mammalian central nervous system are highly diverse in function and molecular composition. Synapse diversity per se may be critical to brain function, since memory and homeostatic mechanisms are thought to be rooted primarily in activity-dependent plastic changes in specific subsets of individual synapses. Unfortunately, the measurement of synapse diversity has been restricted by the limitations of methods capable of measuring synapse properties at the level of individual synapses. Array tomography is a new high-resolution, high-throughput proteomic imaging method that has the potential to advance the measurement of unit-level synapse diversity across large and diverse synapse populations. Here we present an automated feature extraction and classification algorithm designed to quantify synapses from high-dimensional array tomographic data too voluminous for manual analysis. We demonstrate the use of this method to quantify laminar distributions of synapses in mouse somatosensory cortex and validate the classification process by detecting the presence of known but uncommon proteomic profiles. Such classification and quantification will be highly useful in identifying specific subpopulations of synapses exhibiting plasticity in response to perturbations from the environment or the sensory periphery. PMID:23555213

  3. Reentry heat transfer analysis of the space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Ko, W. L.; Quinn, R. D.; Gong, L.

    1982-01-01

    A structural performance and resizing finite element thermal analysis computer program was used in the reentry heat transfer analysis of the space shuttle. Two typical wing cross sections and a midfuselage cross section were selected for the analysis. The surface heat inputs to the thermal models were obtained from aerodynamic heating analyses, which assumed a purely turbulent boundary layer, a purely laminar boundary layer, separated flow, and transition from laminar to turbulent flow. The effect of internal radiation was found to be quite significant. With the effect of the internal radiation considered, the wing lower skin temperature became about 39 C (70 F) lower. The results were compared with fight data for space transportation system, trajectory 1. The calculated and measured temperatures compared well for the wing if laminar flow was assumed for the lower surface and bay one upper surface and if separated flow was assumed for the upper surfaces of bays other than bay one. For the fuselage, good agreement between the calculated and measured data was obtained if laminar flow was assumed for the bottom surface. The structural temperatures were found to reach their peak values shortly before touchdown. In addition, the finite element solutions were compared with those obtained from the conventional finite difference solutions.

  4. Reentry heat transfer analysis of the space shuttle orbiter

    NASA Astrophysics Data System (ADS)

    Ko, W. L.; Quinn, R. D.; Gong, L.

    A structural performance and resizing finite element thermal analysis computer program was used in the reentry heat transfer analysis of the space shuttle. Two typical wing cross sections and a midfuselage cross section were selected for the analysis. The surface heat inputs to the thermal models were obtained from aerodynamic heating analyses, which assumed a purely turbulent boundary layer, a purely laminar boundary layer, separated flow, and transition from laminar to turbulent flow. The effect of internal radiation was found to be quite significant. With the effect of the internal radiation considered, the wing lower skin temperature became about 39 C (70 F) lower. The results were compared with fight data for space transportation system, trajectory 1. The calculated and measured temperatures compared well for the wing if laminar flow was assumed for the lower surface and bay one upper surface and if separated flow was assumed for the upper surfaces of bays other than bay one. For the fuselage, good agreement between the calculated and measured data was obtained if laminar flow was assumed for the bottom surface. The structural temperatures were found to reach their peak values shortly before touchdown. In addition, the finite element solutions were compared with those obtained from the conventional finite difference solutions.

  5. Independent Orbiter Assessment (IOA): Analysis of the nose wheel steering subsystem

    NASA Technical Reports Server (NTRS)

    Mediavilla, Anthony Scott

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Nose Wheel Steering (NWS) hardware are documented. The NWS hardware provides primary directional control for the Orbiter vehicle during landing rollout. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. The original NWS design was envisioned as a backup system to differential braking for directional control of the Orbiter during landing rollout. No real effort was made to design the NWS system as fail operational. The brakes have much redundancy built into their design but the poor brake/tire performance has forced the NSTS to upgrade NWS to the primary mode of directional control during rollout. As a result, a large percentage of the NWS system components have become Potential Critical Items (PCI).

  6. An orbit analysis approach to the study of superintegrable systems in the Euclidean plane

    SciTech Connect

    Adlam, C. M. McLenaghan, R. G. Smirnov, R. G.

    2007-03-15

    We classify the superintegrable potentials in the Euclidean plane by means of an orbit analysis of the space of valence two Killing tensors under the action of the group of rigid motions. Our approach generalizes the classical approach of Winternitz and collaborators by considering pairs of Killing tensors that are not both in canonical form.

  7. Analysis of Binary Multivariate Longitudinal Data via 2-Dimensional Orbits: An Application to the Agincourt Health and Socio-Demographic Surveillance System in South Africa.

    PubMed

    Visaya, Maria Vivien; Sherwell, David; Sartorius, Benn; Cromieres, Fabien

    2014-01-01

    We analyse demographic longitudinal survey data of South African (SA) and Mozambican (MOZ) rural households from the Agincourt Health and Socio-Demographic Surveillance System in South Africa. In particular, we determine whether absolute poverty status (APS) is associated with selected household variables pertaining to socio-economic determination, namely household head age, household size, cumulative death, adults to minor ratio, and influx. For comparative purposes, households are classified according to household head nationality (SA or MOZ) and APS (rich or poor). The longitudinal data of each of the four subpopulations (SA rich, SA poor, MOZ rich, and MOZ poor) is a five-dimensional space defined by binary variables (questions), subjects, and time. We use the orbit method to represent binary multivariate longitudinal data (BMLD) of each household as a two-dimensional orbit and to visualise dynamics and behaviour of the population. At each time step, a point (x, y) from the orbit of a household corresponds to the observation of the household, where x is a binary sequence of responses and y is an ordering of variables. The ordering of variables is dynamically rearranged such that clusters and holes associated to least and frequently changing variables in the state space respectively, are exposed. Analysis of orbits reveals information of change at both individual- and population-level, change patterns in the data, capacity of states in the state space, and density of state transitions in the orbits. Analysis of household orbits of the four subpopulations show association between (i) households headed by older adults and rich households, (ii) large household size and poor households, and (iii) households with more minors than adults and poor households. Our results are compared to other methods of BMLD analysis. PMID:25919116

  8. Analysis of Binary Multivariate Longitudinal Data via 2-Dimensional Orbits: An Application to the Agincourt Health and Socio-Demographic Surveillance System in South Africa

    PubMed Central

    Visaya, Maria Vivien; Sherwell, David; Sartorius, Benn; Cromieres, Fabien

    2015-01-01

    We analyse demographic longitudinal survey data of South African (SA) and Mozambican (MOZ) rural households from the Agincourt Health and Socio-Demographic Surveillance System in South Africa. In particular, we determine whether absolute poverty status (APS) is associated with selected household variables pertaining to socio-economic determination, namely household head age, household size, cumulative death, adults to minor ratio, and influx. For comparative purposes, households are classified according to household head nationality (SA or MOZ) and APS (rich or poor). The longitudinal data of each of the four subpopulations (SA rich, SA poor, MOZ rich, and MOZ poor) is a five-dimensional space defined by binary variables (questions), subjects, and time. We use the orbit method to represent binary multivariate longitudinal data (BMLD) of each household as a two-dimensional orbit and to visualise dynamics and behaviour of the population. At each time step, a point (x, y) from the orbit of a household corresponds to the observation of the household, where x is a binary sequence of responses and y is an ordering of variables. The ordering of variables is dynamically rearranged such that clusters and holes associated to least and frequently changing variables in the state space respectively, are exposed. Analysis of orbits reveals information of change at both individual- and population-level, change patterns in the data, capacity of states in the state space, and density of state transitions in the orbits. Analysis of household orbits of the four subpopulations show association between (i) households headed by older adults and rich households, (ii) large household size and poor households, and (iii) households with more minors than adults and poor households. Our results are compared to other methods of BMLD analysis. PMID:25919116

  9. Atmospheric, Orbital and Secondary Eclipse Analysis of HAT-P-30-WASP-51b

    NASA Astrophysics Data System (ADS)

    Foster, Andrew S.; Harrington, Joseph; Cubillos, Patricio; Blecic, Jasmina; Challener, Ryan; Foster, Austin James; Garland, Justin

    2016-01-01

    HAT-P-30-WASP-51b is a hot-Jupiter planet that orbits an F star every 2.8106 days at a distance of 0.0419 AU. Using the Spitzer Space Telescope in 2012 (Spitzer Program Number 70084) we observed two secondary eclipses of the planet, one in the 3.6 μm channel on 3 January and one in the 4.5 μm channel on 17 January. We present eclipse-depth measurements of 0.00163±0.0001 and 0.00146±0.00013 and we esitmate the infrared brightness temperatures to be 1900±50 and 1600±60 for these two channels, respectively, from an analysis using our Photometry for Orbits, Eclipses, and Transits (POET) pipeline. We also refine its orbit using our own secondary-eclipse measurements in combination with radial-velocity and transit observations from both professional and amateur observers. The most notable result from this orbital analysis is a detection of eccentricity in the planet's orbit. Using only the phase of our secondary eclipses, we can constrain ecosw to a minimum of 0.0084±0.0004, a 20 sigma detection of one component of the orbit's eccentricity that is independent of the effects that stellar tides have on radial velocity data. We then characterize its atmosphere's temperature- pressure profile and molecular abundances using our Bayesian Atmospheric Radiative Transfer code (BART). Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This work was supported by NASA Planetary Atmospheres grant NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G. J. Blecic holds a NASA Earth and Space Sciences Fellowship.

  10. Analysis and optimization of cyclic methods in orbit computation

    NASA Technical Reports Server (NTRS)

    Pierce, S.

    1973-01-01

    The mathematical analysis and computation of the K=3, order 4; K=4, order 6; and K=5, order 7 cyclic methods and the K=5, order 6 Cowell method and some results of optimizing the 3 backpoint cyclic multistep methods for solving ordinary differential equations are presented. Cyclic methods have the advantage over traditional methods of having higher order for a given number of backpoints while at the same time having more free parameters. After considering several error sources the primary source for the cyclic methods has been isolated. The free parameters for three backpoint methods were used to minimize the effects of some of these error sources. They now yield more accuracy with the same computing time as Cowell's method on selected problems. This work is being extended to the five backpoint methods. The analysis and optimization are more difficult here since the matrices are larger and the dimension of the optimizing space is larger. Indications are that the primary error source can be reduced. This will still leave several parameters free to minimize other sources.

  11. Analysis of an Arctic Polesitter. [spacecraft in stationary orbit

    NASA Technical Reports Server (NTRS)

    Driver, J. M.

    1979-01-01

    The concept and rationale are presented and the fundamental dynamical requirements set forth for a spacecraft that remains stationary in space above the North or South Pole of the earth for an extended period of time. The mathematical basis and acceleration characteristics are shown. Performance capability using present day Ion Drive technology is evaluated in terms of stay time at the pole and imaging resolution as a function of viewing distance. The analysis shows that a Polesitter spacecraft can be maintained without difficulty for one or two years at several lunar distances from the earth, admitting large resolution visual imagery and some less useful measurements in the infra-red regime. Microwave measurements are not practical using today's technology. Sensitivity calculations show that substantial improvement in performance capability must await major advances in available technology.

  12. Analysis of the Space Shuttle Orbiter skin panels under simulated hydrodynamic loads

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.; Fasanella, Edwin L.; Jones, Lisa E.

    1988-01-01

    The Space Shuttle orbiter skin panels were analyzed under pressure loads simulating hydrodynamic loads to determine their capability to sustain a potential ditching and to determine pressures that typically would produce failures. Two Dynamic Crash Analysis of Structures (DYCAST) finite element models were used. One model was used to represent skin panels (bays) in the center body, while a second model was used to analyze a fuselage bay in the wing region of the orbiter. From an assessment of the DYCAST nonlinear computer results, it is concluded that the probability is extremely high that most, if not all, of the lower skin panels would rupture under ditching conditions. Extremely high pressure loads which are produced under hydrodynamic planning conditions far exceed the very low predicted failure pressures for the skin panels. Consequently, a ditching of the orbiter is not considered to have a high probability of success and should not be considered a means of emergency landing unless no other option exists.

  13. Analysis of on-orbit thermal characteristics of the 15-meter hoop/column antenna

    NASA Technical Reports Server (NTRS)

    Andersen, Gregory C.; Farmer, Jeffery T.; Garrison, James

    1987-01-01

    In recent years, interest in large deployable space antennae has led to the development of the 15 meter hoop/column antenna. The thermal environment the antenna is expected to experience during orbit is examined and the temperature distributions leading to reflector surface distortion errors are determined. Two flight orientations corresponding to: (1) normal operation, and (2) use in a Shuttle-attached flight experiment are examined. A reduced element model was used to determine element temperatures at 16 orbit points for both flight orientations. The temperature ranged from a minimum of 188 K to a maximum of 326 K. Based on the element temperatures, orbit position leading to possible worst case surface distortions were determined, and the subsequent temperatures were used in a static finite element analysis to quantify surface control cord deflections. The predicted changes in the control cord lengths were in the submillimeter ranges.

  14. Mission design and analysis of European astrophysics missions orbiting libration points

    NASA Astrophysics Data System (ADS)

    Landgraf, Markus; Renk, Florian; de Vogeleer, Bram

    2013-03-01

    The main characteristics of the trajectory design of space observatory missions in the Earth-Sun libration point region is highlighted, based on experiences gained in work performed by the authors on ESA missions. Free transfers always lead to large-amplitude orbits around L2, their properties (amplitudes, phases, non-linear behaviour) are related to the conditions at perigee. Launch scenarios with different degrees of freedom in the perigee geometry and different strategies of sharing the apogee raising between launcher and spacecraft propulsion for Soyuz (with circular parking orbit or direct injection) and Ariane 5 launches from French Guiana will be discussed. Besides the orbit selection and transfer analysis, an important aspect of libration missions is the maintenance of the operational orbit. For some missions it is required to maximise the time between maintenance manoeuvres, and for some the thrust authority is limited. In both cases the exponential nature of the state transition matrix has to be considered. If the equivalent velocity error in the unstable direction becomes too large, the orbit can become unrecoverable, leading to a departure from the environment of the Lagrange point within a few months.

  15. Independent Orbiter Assessment (IOA): Analysis of the life support and airlock support subsystems

    NASA Technical Reports Server (NTRS)

    Arbet, Jim; Duffy, R.; Barickman, K.; Saiidi, Mo J.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Life Support System (LSS) and Airlock Support System (ALSS). Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. The LSS provides for the management of the supply water, collection of metabolic waste, management of waste water, smoke detection, and fire suppression. The ALSS provides water, oxygen, and electricity to support an extravehicular activity in the airlock.

  16. Thermal Analysis Investigation of Dapoxetine and Vardenafil Hydrochlorides using Molecular Orbital Calculations

    PubMed Central

    Attia, Ali Kamal; Souaya, Eglal R.; Soliman, Ethar A.

    2015-01-01

    Purpose: Thermal analysis techniques have been used to study the thermal behavior of dapoxetine and vardenafil hydrochlorides and confirmed using semi-empirical molecular orbital calculations. Methods: Thermogravimetric analysis, derivative thermogravimetry, differential thermal analysis and differential scanning calorimetry were used to determine the thermal behavior and purity of the drugs under investigation. Thermodynamic parameters such as activation energy, enthalpy, entropy and Gibbs free energy were calculated. Results: Thermal behavior of DAP and VAR were confirmed using by semi-empirical molecular orbital calculations. The purity values were found to be 99.97% and 99.95% for dapoxetine and vardenafil hydrochlorides, respectively. The purity of dapoxetine and vardenafil hydrochlorides is similar to that found by reported methods according to DSC data. Conclusion: Thermal analysis justifies its application in quality control of pharmaceutical compounds due to its simplicity, sensitivity and low operational costs. PMID:26819925

  17. Orbital stability analysis and chaotic dynamics of exoplanets in multi-stellar systems

    NASA Astrophysics Data System (ADS)

    Satyal, Suman

    -aperiodic orbits. The stability of the system is defined in terms of its lifetime and maximum eccentricity during the integration period then a regime is established for the known and injected planet's orbital parameters. The de-stabilizing resonances due to the outer planet extend by 1.36 AU towards the star, nonetheless, existence of two Earth-mass planets seems plausible. The radial velocity (RV) curves generated for the test planets reveals a weak RV signal that cannot be measured by currently available instruments. A theory has been developed by extrapolating the radio emission processes in the Jupiter-Io system, which could reveal the presence of exomoons around the giant exoplanets. Based on this theory, maximum distance, radius and masses of exoplanets and exomoons are calculated that could be detected by the available radio telescopes. Observation time at the Low Frequency Array (LOFAR) radio telescope has been proposed to detect exomoon in five different stellar systems. Subjects of my future studies include analysis of the data from LOFAR, search for the additional transiting planets in Kepler 47 circumbinary system and observation at the Subaru telescope to verify the predicted planets in GJ 832 system by the method of direct imaging.

  18. Orbital entanglement and CASSCF analysis of the Ru–NO bond in a Ruthenium nitrosyl complex

    PubMed Central

    Freitag, Leon; Knecht, Stefan; Keller, Sebastian F.; Delcey, Mickaël G.; Aquilante, Francesco; Bondo Pedersen, Thomas; Lindh, Roland

    2015-01-01

    Complete active space self-consistent field (CASSCF) wavefunctions and an orbital entanglement analysis obtained from a density-matrix renormalisation group (DMRG) calculation are used to understand the electronic structure, and, in particular, the Ru–NO bond of a Ru nitrosyl complex. Based on the configurations and orbital occupation numbers obtained for the CASSCF wavefunction and on the orbital entropy measurements evaluated for the DMRG wavefunction, we unravel electron correlation effects in the Ru coordination sphere of the complex. It is shown that Ru–NO π bonds show static and dynamic correlation, while other Ru–ligand bonds feature predominantly dynamic correlation. The presence of static correlation requires the use of multiconfigurational methods to describe the Ru–NO bond. Subsequently, the CASSCF wavefunction is analysed in terms of configuration state functions based on localised orbitals. The analysis of the wavefunctions in the electronic singlet ground state and the first triplet state provides a picture of the Ru–NO moiety beyond the standard representation based on formal oxidation states. A distinct description of the Ru and NO fragments is advocated. The electron configuration of Ru is an equally weighted superposition of RuII and RuIII configurations, with the RuIII configuration originating from charge donation mostly from Cl ligands. However, and contrary to what is typically assumed, the electronic configuration of the NO ligand is best described as electroneutral. PMID:25767830

  19. Gap symmetry and stability analysis in the multi-orbital Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Fischer, Mark H.

    2013-07-01

    The iron-based superconductors allow for a zoo of possible order parameters due to their orbital degrees of freedom. These order parameters are often written in an orbital basis for a microscopic analysis and a comprehensive symmetry classification. Unlike in standard single-band superconductors, where electrons of the same band—and hence, energy—are paired, a general order parameter in such a multi-orbital system also contains pairing of electrons belonging to different bands. As this corresponds to pairing of electrons of different energy, such order parameters are energetically less stable. Here, we present a simple criterion for a stability analysis of the orbital part of the gap function based on the basic principle that electrons of equal energy are paired in the superconducting state. This not only allows us to find the most stable states, but also to identify the terms in a (tight-binding) Hamiltonian suppressing any given superconducting state. Our approach thus allows us to identify the minimal Hamiltonian necessary to compare competing instabilities.

  20. Space Trajectory Error Analysis Program (STEAP) for halo orbit missions. Volume 1: Analytic and user's manual

    NASA Technical Reports Server (NTRS)

    Byrnes, D. V.; Carney, P. C.; Underwood, J. W.; Vogt, E. D.

    1974-01-01

    Development, test, conversion, and documentation of computer software for the mission analysis of missions to halo orbits about libration points in the earth-sun system is reported. The software consisting of two programs called NOMNAL and ERRAN is part of the Space Trajectories Error Analysis Programs (STEAP). The program NOMNAL targets a transfer trajectory from Earth on a given launch date to a specified halo orbit on a required arrival date. Either impulsive or finite thrust insertion maneuvers into halo orbit are permitted by the program. The transfer trajectory is consistent with a realistic launch profile input by the user. The second program ERRAN conducts error analyses of the targeted transfer trajectory. Measurements including range, doppler, star-planet angles, and apparent planet diameter are processed in a Kalman-Schmidt filter to determine the trajectory knowledge uncertainty. Execution errors at injection, midcourse correction and orbit insertion maneuvers are analyzed along with the navigation uncertainty to determine trajectory control uncertainties and fuel-sizing requirements. The program is also capable of generalized covariance analyses.

  1. Numerical analysis and experiment research on fluid orbital performance of vane type propellant management device

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Li, Y.; Pan, H. L.; Liu, J. T.; Zhuang, B. T.

    2015-01-01

    Vane type propellant management device (PMD) is one of the key components of the vane-type surface tension tank (STT), and its fluid orbital performance directly determines the STT's success or failure. In present paper, numerical analysis and microgravity experiment study on fluid orbital performance of a vane type PMD were carried out. By using two-phase flow model of volume of fluid (VOF), fluid flow characteristics in the tank with the vane type PMD were numerically calculated, and the rules of fluid transfer and distribution were gotten. A abbreviate model test system of the vane type PMD is established and microgravity drop tower tests were performed, then fluid management and transmission rules of the vane type PMD were obtained under microgravity environment. The analysis and tests results show that the vane type PMD has good and initiative fluid orbital management ability and meets the demands of fluid orbital extrusion in the vane type STT. The results offer valuable guidance for the design and optimization of the new generation of vane type PMD, and also provide a new approach for fluid management and control in space environment.

  2. Orbital entanglement and CASSCF analysis of the Ru-NO bond in a Ruthenium nitrosyl complex.

    PubMed

    Freitag, Leon; Knecht, Stefan; Keller, Sebastian F; Delcey, Mickaël G; Aquilante, Francesco; Pedersen, Thomas Bondo; Lindh, Roland; Reiher, Markus; González, Leticia

    2015-06-14

    Complete active space self-consistent field (CASSCF) wavefunctions and an orbital entanglement analysis obtained from a density-matrix renormalisation group (DMRG) calculation are used to understand the electronic structure, and, in particular, the Ru-NO bond of a Ru nitrosyl complex. Based on the configurations and orbital occupation numbers obtained for the CASSCF wavefunction and on the orbital entropy measurements evaluated for the DMRG wavefunction, we unravel electron correlation effects in the Ru coordination sphere of the complex. It is shown that Ru-NO π bonds show static and dynamic correlation, while other Ru-ligand bonds feature predominantly dynamic correlation. The presence of static correlation requires the use of multiconfigurational methods to describe the Ru-NO bond. Subsequently, the CASSCF wavefunction is analysed in terms of configuration state functions based on localised orbitals. The analysis of the wavefunctions in the electronic singlet ground state and the first triplet state provides a picture of the Ru-NO moiety beyond the standard representation based on formal oxidation states. A distinct description of the Ru and NO fragments is advocated. The electron configuration of Ru is an equally weighted superposition of Ru(II) and Ru(III) configurations, with the Ru(III) configuration originating from charge donation mostly from Cl ligands. However, and contrary to what is typically assumed, the electronic configuration of the NO ligand is best described as electroneutral. PMID:25767830

  3. Independent Orbiter Assessment (IOA): Analysis of the active thermal control subsystem

    NASA Technical Reports Server (NTRS)

    Sinclair, S. K.; Parkman, W. E.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical (PCIs) items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Active Thermal Control Subsystem (ATCS) are documented. The major purpose of the ATCS is to remove the heat, generated during normal Shuttle operations from the Orbiter systems and subsystems. The four major components of the ATCS contributing to the heat removal are: Freon Coolant Loops; Radiator and Flow Control Assembly; Flash Evaporator System; and Ammonia Boiler System. In order to perform the analysis, the IOA process utilized available ATCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 310 failure modes analyzed, 101 were determined to be PCIs.

  4. Independent Orbiter Assessment (IOA): Analysis of the electrical power generation/fuel cell powerplant subsystem

    NASA Technical Reports Server (NTRS)

    Brown, K. L.; Bertsch, P. J.

    1986-01-01

    Results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Generation (EPG)/Fuel Cell Powerplant (FCP) hardware. The EPG/FCP hardware is required for performing functions of electrical power generation and product water distribution in the Orbiter. Specifically, the EPG/FCP hardware consists of the following divisions: (1) Power Section Assembly (PSA); (2) Reactant Control Subsystem (RCS); (3) Thermal Control Subsystem (TCS); and (4) Water Removal Subsystem (WRS). The IOA analysis process utilized available EPG/FCP hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  5. Requirement Analysis of Orbital Parameters in the Satellite-to-Satellite Tracking Model

    NASA Astrophysics Data System (ADS)

    Zheng, W.; Hsu, H. T.; Zhong, M.; Yun, M. J.; Zhou, X. H.; Peng, B. B.

    2010-01-01

    The 21st century is a new epoch that human beings upgrade the cognitive capabilities to the Digital Earth using the SST (Satellite-to-Satellite Tracking) and SGG (Satellite Gravity Gradiometry) techniques. The requirement analysis of orbital parameters in the SST model is carried out for the first time using the combined models of cumulative geoid height errors influenced by the range-rate error of K-band ranging system, orbital error of GPS receiver and nonconservative force error of accelerometer from GRACE satellites based on the semi-analytical method in this study. The simulated results are as follows: (1) The matched relationship of accuracy indexes from key payloads including K-band ranging system, GPS receiver and accelerometer is obtained using the semi-analytical method; (2) The GRACE global gravitational field is estimated based on different average orbital altitudes (500 km, 450 km, 400 km, 350 km, 300 km, 250 km and 200 km) and average intersatellite ranges (110 km, 220 km and 330 km). The optimal design of average orbital altitude 400 km and intersatellite range 220 km is suggested in the future first gravity satellite in China. The reasons why the preferable orbital altitude and intersatellite range are selected are analyzed and demonstrated in detail. This work not only can provide theoretical foundation and calculational guarantee for the optimal selection of orbital parameters and efficient and rapid estimation on the accuracy of global gravitational field in the future satellite gravity measurement in China, but also has some guiding significance to the development direction of future international GRACE Follow-On Earth's gravity measurement mission and GRAIL lunar gravity exploration program.

  6. Energy Balance and Power Performance Analysis for Satellite in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Jang, Sung-Soo; Kim, Sung-Hoon; Lee, Sang-Ryool; Choi, Jaeho

    2010-09-01

    The electrical power system (EPS) of Korean satellites in low-earth-orbit is designed to achieve energy balance based on a one-orbit mission scenario. This means that the battery has to be fully charged at the end of a one-orbit mission. To provide the maximum solar array (SA) power generation, the peak power tracking (PPT) method has been developed for a spacecraft power system. The PPT is operated by a software algorithm, which tracks the peak power of the SA and ensures the battery is fully charged in one orbit. The EPS should be designed to avoid the stress of electronics in order to handle the main bus power from the SA power. This paper summarizes the results of energy balance to achieve optimal power sizing and the actual trend analysis of EPS performance in orbit. It describes the results of required power for the satellite operation in the worst power conditions at the end-of-life, the methods and input data used in the energy balance, and the case study of energy balance analyses for the normal operation in orbit. Both 10:35 AM and 10:50 AM crossing times are considered, so the power performance in each case is analyzed with the satellite roll maneuver according to the payload operation concept. In addition, the data transmission to the Korea Ground Station during eclipse is investigated at the local-time-ascending-node of 11:00 AM to assess the greatest battery depth-of-discharge in normal operation.

  7. Satellite Power Systems (SPS) concept definition study. Volume 5: Transportation and operations analysis. [heavy lift launch and orbit transfer vehicles for orbital assembly

    NASA Technical Reports Server (NTRS)

    Hanley, G.

    1978-01-01

    The development of transportation systems to support the operations required for the orbital assembly of a 5-gigawatt satellite is discussed as well as the construction of a ground receiving antenna (rectenna). Topics covered include heavy lift launch vehicle configurations for Earth-to LEO transport; the use of chemical, nuclear, and electric orbit transfer vehicles for LEO to GEO operations; personnel transport systems; ground operations; end-to-end analysis of the construction, operation, and maintenance of the satellite and rectenna; propellant production and storage; and payload packaging.

  8. A mathematical analysis of small mammal populations.

    PubMed

    Hoppensteadt, F C; Murphy, L

    1987-01-01

    Populations of Microtus montanus, the montane vole, have been extensively studied. It is known that their reproductive activity is closely linked to the availability of the chemicals in growing plants. We use a mathematical model here to study how the length of the vegetative season and the natural reproduction rhythm of voles are involved in the long term dynamics of the population numbers. In particular, we use data obtained from Timpie Springs, Utah, and from Jackson Hole, Wyoming, to formulate a model. The novelty of this model is its use of littering curves that highlight the temporally discrete nature of vole reproduction. The model shows how the timing of the vegetative season can influence vole population sizes. PMID:3305751

  9. Independent Orbiter Assessment (IOA): Analysis of the landing/deceleration subsystem

    NASA Technical Reports Server (NTRS)

    Compton, J. M.; Beaird, H. G.; Weissinger, W. D.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Landing/Deceleration Subsystem hardware. The Landing/Deceleration Subsystem is utilized to allow the Orbiter to perform a safe landing, allowing for landing-gear deploy activities, steering and braking control throughout the landing rollout to wheel-stop, and to allow for ground-handling capability during the ground-processing phase of the flight cycle. Specifically, the Landing/Deceleration hardware consists of the following components: Nose Landing Gear (NLG); Main Landing Gear (MLG); Brake and Antiskid (B and AS) Electrical Power Distribution and Controls (EPD and C); Nose Wheel Steering (NWS); and Hydraulics Actuators. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Due to the lack of redundancy in the Landing/Deceleration Subsystems there is a high number of critical items.

  10. Comprehensive analysis of Shuttle Orbiter leeside surface infrared imagery obtained during atmospheric entry

    NASA Technical Reports Server (NTRS)

    Myrick, D. L.; Throckmorton, D. A.

    1986-01-01

    The thermographic analysis techniques developed for processing of data from the Shuttle Infrared Leeside Temperature Sensing (SILTS) experiment are discussed. The SILTS experiment will obtain high-spatial-resolution infrared images of the leeside of the Space Shuttle Orbiter during atmospheric entry by means of a scanning infrared radiometer located atop the orbiter's vertical stabilizer. Comprehensive analysis of the SILTS thermography requires accurate consideration of all those factors (such as geometry of the observed surfaces, local surface emissivity, solar radiation, and other potential sources of image degradation) which may potentially affect the output of the infrared radiometer. An overview of the entire data processing procedure and brief descriptions of the data processing algorithms are presented.

  11. Mission and sizing analysis for the Beta 2 two-stage-to-orbit vehicle

    NASA Technical Reports Server (NTRS)

    Nadell, Shari-Beth; Baumgarten, William J.; Alexander, Stephen W.

    1992-01-01

    NASA Lewis Research Center studied a horizontal takeoff and landing, fully reusable, two-stage-to-orbit (TSTO) vehicle capable of launching and returning a 10,000 pound payload to low Earth polar orbit using low-risk technology. The vehicle, called Beta 2, was derived from the USAF/Boeing Beta vehicle, a TSTO study vehicle capable of launching a 50,000 pound payload to low Earth polar orbit. Development of the Beta 2 from the USAF/Boeing Beta vehicle occurred in a series of iterations during which the size of the vehicle was decreased to accommodate the smaller payload, the staging Mach number was decreased from 8.0 to 6.5, and the rocket propulsion system was removed from the booster. The final Beta 2 vehicle consisted of a rocket powered orbiter and an all airbreathing booster. The gross takeoff weight of the Beta 2 vehicle was approximately 1.1 million pounds. In addition to its baseline mission, the Beta 2 was capable of delivering approximately 17,500 pounds to the Space Station with the same takeoff gross weight. The mission and sizing analysis performed to arrived at the Beta 2 vehicle is discussed.

  12. The Inner Magnetospheric Imager (IMI): Instrument heritage and orbit viewing analysis

    NASA Technical Reports Server (NTRS)

    Wilson, Gordon R.

    1992-01-01

    For the last two years an engineering team in the Program Development Office at MSFC has been doing design studies for the proposed Inner Magnetospheric Imager (IMI) mission. This team had a need for more information about the instruments that this mission would carry so that they could get a better handle on instrument volume, mass, power, and telemetry needs as well as information to help assess the possible cost of such instruments and what technology development they would need. To get this information, an extensive literature search was conducted as well as interviews with several members of the IMI science working group. The results of this heritage survey are summarized below. There was also a need to evaluate the orbits proposed for this mission from the stand point of their suitability for viewing the various magnetospheric features that are planned for this mission. This was accomplished by first, identifying the factors which need to be considered in selecting an orbit, second, translating these considerations into specific criteria, and third, evaluating the proposed orbits against these criteria. The specifics of these criteria and the results of the orbit analysis are contained in the last section of this report.

  13. Post-flight differential correction analysis using Vinti's spheroidal method for the small astronomy satellite orbit

    NASA Technical Reports Server (NTRS)

    Walden, H.

    1974-01-01

    The results of an intensive analysis of a differential orbit improvement method utilizing observational data for a 550-kilometer altitude, near-circular, near-equatorial satellite orbit are presented. Observations of the Small Astronomy Satellite (SAS-1) are in the form of direction cosines as measured at two ground interferometer tracking stations near the Equator during the first 22 orbital revolutions (approximately 37 hours) after launch of the spacecraft. Numerical results, in both tabular and graphical form, are displayed for numerous iterated fittings of various observational arcs by differential correction of the orbital elements. Parameters varied in these comparative cases include the time duration of the observational data block, the number of pairs of direction cosine data and the number of tracking station passes included in the solution, the distribution of such passes between the two available tracking stations, and the acceptance criterion for the observational residuals in the least squares fitting procedure. It was found that three observational pairs of direction cosine data, the minimum number possible for a uniquely determined solution in theory, are sufficient to promote covergence to an accurate solution, if properly selected.

  14. Preliminary solutions for the lunar gravity field from analysis of lunar orbiter tracking data

    NASA Technical Reports Server (NTRS)

    Lemoine, F. G.; Smith, D. E.; Zuber, M. T.; Rowlands, D. D.; Fricke, S. K.

    1994-01-01

    Knowledge of the gravitation field, in combination with surface topography, provides one of the principal means of inferring the internal structure of a planetary body. Previous analyses of the lunar gravitational field have been based on data from the Lunar Orbiters, the Apollo subsatellites, and the low altitude passes of the Apollo spacecraft. Recently, Konopliv et al. have reanalyzed all available Lunar Orbiter and Apollo subsatellite tracking data, producing a 60th degree and order solution. In preparation for the Clementine Mission to the Moon, we have also initiated a reanalysis of the Lunar Orbiter and Apollo subsatellite data. Our reanalysis takes advantage of advanced force and measurement modeling techniques as well as modern computational facilities. We applied the least squares collocation technique which stabilizes the behavior of the solution and high degree and order. The extension of the size of the field reduces the aliasing coming from the omitted portion of the gravitational field. This is especially important for the analysis of the tracking data from the Lunar Orbiters, as the periapse heights frequently ranged from 50 to 100 km.

  15. Finite-element reentry heat-transfer analysis of space shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Quinn, Robert D.; Gong, Leslie

    1986-01-01

    A structural performance and resizing (SPAR) finite-element thermal analysis computer program was used in the heat-transfer analysis of the space shuttle orbiter subjected to reentry aerodynamic heating. Three wing cross sections and one midfuselage cross section were selected for the thermal analysis. The predicted thermal protection system temperatures were found to agree well with flight-measured temperatures. The calculated aluminum structural temperatures also agreed reasonably well with the flight data from reentry to touchdown. The effects of internal radiation and of internal convection were found to be significant. The SPAR finite-element solutions agreed reasonably well with those obtained from the conventional finite-difference method.

  16. Analysis methods and preliminary design study. [of the shuttle orbiter body flaps

    NASA Technical Reports Server (NTRS)

    Blackburn, C. L.; Robinson, J. C.

    1979-01-01

    The shuttle orbiter body flap was studied to define loads and temperatures and to assess various structural concepts. Laminated-structure analysis capability was required. An appraisal of the available structural analysis programs, NASTRAN and SPAR, indicates that neither had all the capabilities required. The thermal analysis program, MITAS solved the problem once a model was generated but model generation and verification was laborious and transfer of temperatures to the structural program usually required interpolation. Therefore it was decided to incorporate both capabilities in the SPAR finite element program.

  17. Preliminary Analysis of STS-3 Entry Heat-Transfer Data for the Orbiter Windward Centerline

    NASA Technical Reports Server (NTRS)

    Throckmorton, D. A.; Hamilton, H. H., II; Zoby, E. V.

    1982-01-01

    A preliminary analysis of heat transfer data on the space shuttle orbiter windward centerline for the STS-3 mission entry is presented. Temperature-time history plots for each measurement location and tabulated wall temperature and convective heating rate data at 21 selected trajectory points are included. The STS-3 flight data are also compared with predictions by two approximation methods for computing convective heat transfer rates in equilibrium air.

  18. Macroinformational analysis of conditions for controllability of space-vehicle orbit

    NASA Astrophysics Data System (ADS)

    Glazov, B. I.

    2011-12-01

    The general axiomatics of information measures for the macro analysis of relations of an information-cybernetic system in the control is introduced. The general structure of a semantically marked graph of open and closed relations of an information-cybernetic system between the participants in the environment, as well as thenecessary axiomatic and technological information-cybernetic system conditions of controllability and observability of objects, for the case of a space vehicle in orbit, are justified.

  19. Analysis of Shuttle Orbiter Reliability and Maintainability Data for Conceptual Studies

    NASA Technical Reports Server (NTRS)

    Morris, W. D.; White, N. H.; Ebeling, C. E.

    1996-01-01

    In order to provide a basis for estimating the expected support required of new systems during their conceptual design phase, Langley Research Center has recently collected Shuttle Orbiter reliability and maintainability data from the various data base sources at Kennedy Space Center. This information was analyzed to provide benchmarks, trends, and distributions to aid in the analysis of new designs. This paper presents a summation of those results and an initial interpretation of the findings.

  20. New Population Synthesis Techniques in the Analysis of Interacting Binaries

    NASA Astrophysics Data System (ADS)

    Nelson, Lorne

    2012-02-01

    Novel approaches to understanding the observed properties of interacting binaries containing compact accretors such as neutron stars and white dwarfs are examined. Explaining the evolution of these systems is a computationally challenging problem because the vector space of initial conditions that describes the progenitor binaries is wide-ranging. There are large variations in the chemical abundance (e.g., metallicity), binary mass correlations, and assumed input physics. In this paper we compare two very different strategies to synthesize a specific subset of the currently observed population of compact binaries. Both involve the pre-computing a large grid of representative models. In the first case, the grid of initial conditions is densely packed thereby allowing us to identify the spectrum of initial conditions and the most probable evolutionary channels leading to the formation of the observed binaries. In the second, the grid is accurately interpolated to provide us with the ensemble properties of the currently observed population of interacting binaries (e.g., Cataclysmic Variables). As an example of the utility of the first approach, we have taken advantage of the multicore processing power of the fast, new stellar evolution code known as MESA to compute an extensive grid of binary evolution tracks for low- and intermediate-mass X-ray binaries. The grid is about two orders of magnitude larger than any previous computation of X-ray binary evolution and includes more than 40,000 models. It comprises 60 initial donor masses over the range of 1 to 4 Modot and, for each of these, 700 initial orbital periods over the range of 10 to 250 hours were chosen. Using a 'traceback' analysis, we show how the extremely massive neutron star (1.97 Modot) in the binary pulsar PSR J1614-2230 is likely to have evolved. We find that the initial donor stars which produce the closest relatives to PSR J1614-2230 are likely to have had a mass of between approximately 3.4 to 3

  1. Three-Dimensional Pre-Bent Titanium Implant for Concomitant Orbital Floor and Medial Wall Fractures in an East Asian Population

    PubMed Central

    Lee, Kyung Min; Park, Ji Ung; Kwon, Sung Tack; Kim, Suk Wha

    2014-01-01

    Background The objective of this article is to evaluate clinical outcomes of combined orbital floor and medial wall fracture repair using a three-dimensional pre-bent titanium implant in an East Asian population. Methods Clinical and radiologic data were analyzed for 11 patients with concomitant orbital floor and medial wall fractures. A combined transcaruncular and inferior fornix approach with lateral canthotomy was used for the exposure of fractures. An appropriate three-dimensional preformed titanium implant was selected and inserted according to the characteristics of a given defect. Results Follow-up time ranged from 2 to 6 months (median, 4.07 months). All patients had a successful treatment outcome without any complications. Clinically significant enophthalmos was not observed after treatment. Conclusions Three-dimensional pre-bent titanium implants are appropriate for use in the East Asian population, with a high success rate of anatomic restoration of the orbital volume and prevention of enophthalmos in combined orbital floor and medial wall fracture cases. PMID:25276638

  2. Analysis of Multi-Satellite Tracking Data of the Kaguya Satellites for Orbit and Gravity Field Determination

    NASA Astrophysics Data System (ADS)

    Goossens, S. J.; Matsumoto, K.; Kikuchi, F.; Liu, Q.; Hanada, H.; Lemoine, F. G.; Rowlands, D. D.; Ishihara, Y.; Jianguo, Y.; Araki, H.; Noda, H.; Namiki, N.; Iwata, T.

    2010-12-01

    The Kaguya spacecraft were launched from Tanegashima Space Center on September 14, 2007. Kaguya consists of three orbiters: a main orbiter in a low-altitude (100 km) circular polar orbit, and two sub-satellites (Rstar and Vstar) in elliptical orbits. The satellites were tracked by a variety of terrestrial based tracking systems: in addition to standard two-way Doppler and range tracking, there was 4-way Doppler tracking between Rstar and the main orbiter, providing the first tracking data of a satellite over the lunar far side, and there was same-beam differential VLBI tracking between the two sub-satellites, providing precise orbits for these satellites. The main orbiter was also equipped with a laser altimeter (LALT) to measure the topography of the Moon. At points where the ground tracks of different orbits intersect, these data can provide further constraints on the orbit of the main satellite in the form of crossovers, as essentially the same topography should be measured. This comprehensive data set between the satellites allows for a unique opportunity to evaluate the contribution of these tracking systems to orbit and gravity field determination. Precise orbits are important for geolocation of the topography and camera data, whereas the gravity field can be used for studies of the lunar interior. Here, we present the analysis of the combinations of these tracking data. The use of 4-way and same-beam differential VLBI data leads to large improvements in orbit precision of all satellites involved, where especially peaks in orbit overlap differences during edge-on periods are reduced. The use of the altimetry crossovers improves the orbit of the main satellite further, resulting in an orbit precision of in general less than 20 m. We have also used the full set of SELENE tracking data (including all 4-way and all S-band same-beam differential VLBI data), together with historical data, for gravity field determination. We show a lunar gravity field model with an

  3. Projecting the success of plant restoration with population viability analysis

    USGS Publications Warehouse

    Bell, T.J.; Bowles, M.L.; McEachern, A.K.

    2003-01-01

    Conserving viable populations of plant species requires that they have high probabilities of long-term persistence within natural habitats, such as a chance of extinction in 100 years of less than 5% (Menges 1991, 1998; Brown 1994; Pavlik 1994; Chap. 1, this Vol.). For endangered and threatened species that have been severely reduces in range and whose habitats have been fragmented, important species conservation strategies may include augmenting existing populations or restoring new viable populations (Bowles and Whelan 1994; Chap. 2, this Vol.). Restoration objectives may include increasing population numbers to reduce extinction probability, deterministic manipulations to develop a staged cohort structure, or more complex restoration of a desired genetic structure to allow outcrossing or increase effective population size (DeMauro 1993, 1994; Bowles et al. 1993, 1998; Pavlik 1994; Knapp and Dyer 1998; Chap. 2, this Vol.). These efforts may require translocation of propagules from existing (in situ) populations, or from ex situ botanic gardens or seed storage facilities (Falk et al. 1996; Guerrant and Pavlik 1998; Chap. 2, this Vol.). Population viability analysis (PVA) can provide a critical foundation for plant restoration, as it models demographic projections used to evaluate the probability of population persistence and links plant life history with restoration strategies. It is unknown how well artificially created populations will meet demographic modeling requirements (e.g., due to artificial cohort transitions) and few, if any, PVAs have been applied to restorations. To guide application of PVA to restored populations and to illustrate potential difficulties, we examine effects of planting different life stages, model initial population sizes needed to achieve population viability, and compare demographic characteristics between natural and restored populations. We develop and compare plant population restoration viability analysis (PRVA) case studies of

  4. Vibrational spectra, molecular structure, natural bond orbital, first order hyperpolarizability, thermodynamic analysis and normal coordinate analysis of Salicylaldehyde p-methylphenylthiosemicarbazone by density functional method.

    PubMed

    Porchelvi, E Elamurugu; Muthu, S

    2015-01-01

    The thiosemicarbazone compound, Salicylaldehyde p-methylphenylthiosemicarbazone (abbreviated as SMPTSC) was synthesized and characterized by FTIR, FT-Raman and UV. Density functional (DFT) calculations have been carried out for the title compound by performing DFT level of theory using B3LYP/6-31++G(d,p) basis set. The molecular geometry and vibrational frequencies were calculated and compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The electronic dipole moment (μD) and the first hyperpolarizability (βtot) values of the investigated molecule were computed using density functional theory (DFT/B3LYP) with 6-311++G(d,p) basis set. The stability and charge delocalization of the molecule was studied by natural bond orbital (NBO) analysis. Thearomaticities of the phenyl rings were studied using the standard harmonic oscillator model of aromaticity (HOMA) index. Mulliken population analysis on atomic charges is also calculated. The molecule orbital contributions are studied by density of energy states (DOSs). PMID:25033238

  5. Observations and Orbital Analysis of the High-Amplitude Delta Scuti Star SZLyncis: The Unusual Orbital Precession

    NASA Astrophysics Data System (ADS)

    Li, Lin-Jia; Qian, Sheng-Bang

    2013-12-01

    We determined forty-two new times of light maximum from our photometry observations and WASP project, and collected all times of light maximum observed between 1961 and 2013 in order to calculate the orbital elements of the SZ Lyncis system and the secular change of the pulsation period with the classical O - C method. We confirmed the decrease of the longitude of the periastron passage with a rate of (-1.˚15 ±0.˚25) yr-1 , and discussed the causative mechanism. The results show that the precession of the star's orbit might be due to a close binary system, which means that the companion of SZ Lyncis is actually a binary system. We used the Hipparcos Intermediate Astrometric Data to obtain the complete orbital elements of the SZ Lyncis system, and found that the inclination, i, and parallax, πt , are 39.˚5 ± 17.˚7 and 2.61 ± 0.98 mas (corresponds to 380 ± 140 pc), respectively. We reanalyzed the mean radial velocities of SZ Lyncis given by Bardin and Imbert (1984), and noticed a weak variation existing in the residuals from a single-Keplerian fit. We suggest that more detailed high-precision spectroscopic observations are definitely needed in the future to check this short periodic change.

  6. Orbital Debris

    NASA Technical Reports Server (NTRS)

    Kessler, D. J. (Compiler); Su, S. Y. (Compiler)

    1985-01-01

    Earth orbital debris issues and recommended future activities are discussed. The workshop addressed the areas of environment definition, hazards to spacecraft, and space object management. It concluded that orbital debris is a potential problem for future space operations. However, before recommending any major efforts to control the environment, more data are required. The most significant required data are on the population of debris smaller than 4 cm in diameter. New damage criteria are also required. When these data are obtained, they can be combined with hypervelocity data to evaluate the hazards to future spacecraft. After these hazards are understood, then techniques to control the environment can be evaluated.

  7. Independent Orbiter Assessment (IOA): Analysis of the guidance, navigation, and control subsystem

    NASA Technical Reports Server (NTRS)

    Trahan, W. H.; Odonnell, R. A.; Pietz, K. C.; Hiott, J. M.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) is presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Guidance, Navigation, and Control (GNC) Subsystem hardware are documented. The function of the GNC hardware is to respond to guidance, navigation, and control software commands to effect vehicle control and to provide sensor and controller data to GNC software. Some of the GNC hardware for which failure modes analysis was performed includes: hand controllers; Rudder Pedal Transducer Assembly (RPTA); Speed Brake Thrust Controller (SBTC); Inertial Measurement Unit (IMU); Star Tracker (ST); Crew Optical Alignment Site (COAS); Air Data Transducer Assembly (ADTA); Rate Gyro Assemblies; Accelerometer Assembly (AA); Aerosurface Servo Amplifier (ASA); and Ascent Thrust Vector Control (ATVC). The IOA analysis process utilized available GNC hardware drawings, workbooks, specifications, schematics, and systems briefs for defining hardware assemblies, components, and circuits. Each hardware item was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  8. Dynamical-systems analysis and unstable periodic orbits in reacting flows behind symmetric bluff bodies.

    PubMed

    Hua, Jia-Chen; Gunaratne, Gemunu H; Kostka, Stanislav; Jiang, Naibo; Kiel, Barry V; Gord, James R; Roy, Sukesh

    2013-09-01

    Dynamical systems analysis is performed for reacting flows stabilized behind four symmetric bluff bodies to determine the effects of shape on the nature of flame stability, acoustic coupling, and vortex shedding. The task requires separation of regular, repeatable aspects of the flow from experimental noise and highly irregular, nonrepeatable small-scale structures caused primarily by viscous-mediated energy cascading. The experimental systems are invariant under a reflection, and symmetric vortex shedding is observed throughout the parameter range. As the equivalence ratio-and, hence, acoustic coupling-is reduced, a symmetry-breaking transition to von Karman vortices is initiated. Combining principal-components analysis with a symmetry-based filtering, we construct bifurcation diagrams for the onset and growth of von Karman vortices. We also compute Lyapunov exponents for each flame holder to help quantify the transitions. Furthermore, we outline changes in the phase-space orbits that accompany the onset of von Karman vortex shedding and compute unstable periodic orbits (UPOs) embedded in the complex flows prior to and following the bifurcation. For each flame holder, we find a single UPO in flows without von Karman vortices and a pair of UPOs in flows with von Karman vortices. These periodic orbits organize the dynamics of the flow and can be used to reduce or control flow irregularities. By subtracting them from the overall flow, we are able to deduce the nature of irregular facets of the flows. PMID:24125348

  9. Stream network analysis from orbital and suborbital imagery, Colorado River Basin, Texas

    NASA Technical Reports Server (NTRS)

    Baker, V. R. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Orbital SL-2 imagery (earth terrain camera S-190B), received September 5, 1973, was subjected to quantitative network analysis and compared to 7.5 minute topographic mapping (scale: 1/24,000) and U.S.D.A. conventional black and white aerial photography (scale: 1/22,200). Results can only be considered suggestive because detail on the SL-2 imagery was badly obscured by heavy cloud cover. The upper Bee Creek basin was chosen for analysis because it appeared in a relatively cloud-free portion of the orbital imagery. Drainage maps were drawn from the three sources digitized into a computer-compatible format, and analyzed by the WATER system computer program. Even at its small scale (1/172,000) and with bad haze the orbital photo showed much drainage detail. The contour-like character of the Glen Rose Formation's resistant limestone units allowed channel definition. The errors in pattern recognition can be attributed to local areas of dense vegetation and to other areas of very high albedo caused by surficial exposure of caliche. The latter effect caused particular difficulty in the determination of drainage divides.

  10. Orbital transfer vehicle concept definition and systems analysis study. Volume 11: Study extension 2 results

    NASA Technical Reports Server (NTRS)

    Willcockson, W. H.

    1988-01-01

    Work conducted in the second extension of the Phase A Orbit Transfer Vehicle Concept Definition and Systems Analysis Study is summarized. Four major tasks were identified: (1) define an initial OTV program consistent with near term Civil Space Leadership Initiative missions; (2) develop program evolution to long term advanced missions; (3) investigate the implications of current STS safety policy on an Aft Cargo Carrier based OTV; and (4) expand the analysis of high entry velocity aeroassist. An increased emphasis on the breath of OTV applications was undertaken to show the need for the program on the basis of the expansion of the nation's capabilities in space.

  11. Design and performance analysis of an aero-maneuvering orbital-transfer vehicle concept

    NASA Technical Reports Server (NTRS)

    Menees, G. P.

    1985-01-01

    Systems requirements for design-optimized, lateral-turn performance were determined for reusable, space-based applications and low-Earth orbits involving large multiple plane-inclination changes. The aerothermodynamic analysis is the most advanced available for rarefield-hypersonic flow over lifting surfaces at incidence. The effects of leading-edge bluntness, low-density viscous phenomena, and finite-rate flow-field chemistry and surface catalysis are accounted for. The predicted aerothermal heating characteristics are correlated with thermal-control and flight-performance capabilities. The mission payload capacity for delivery, retrieval, and combined operations was determined for round-trip sorties extending to polar orbits. Recommendations are given for future design refinements. The results help to identify technology issues required to develop prototype operational vehicles.

  12. Photogrammetric analysis of horizon panoramas: The Pathfinder landing site in Viking orbiter images

    USGS Publications Warehouse

    Oberst, J.; Jaumann, R.; Zeitler, W.; Hauber, E.; Kuschel, M.; Parker, T.; Golombek, M.; Malin, M.; Soderblom, L.

    1999-01-01

    Tiepoint measurements, block adjustment techniques, and sunrise/sunset pictures were used to obtain precise pointing data with respect to north for a set of 33 IMP horizon images. Azimuth angles for five prominent topographic features seen at the horizon were measured and correlated with locations of these features in Viking orbiter images. Based on this analysis, the Pathfinder line/sample coordinates in two raw Viking images were determined with approximate errors of 1 pixel, or 40 m. Identification of the Pathfinder location in orbit imagery yields geological context for surface studies of the landing site. Furthermore, the precise determination of coordinates in images together with the known planet-fixed coordinates of the lander make the Pathfinder landing site the most important anchor point in current control point networks of Mars. Copyright 1999 by the American Geophysical Union.

  13. Spacecraft Orbit Design and Analysis (SODA). Version 2.0: User's guide

    NASA Technical Reports Server (NTRS)

    Stallcup, Scott S.; Davis, John S.; Zsoldos, Jeffrey S.

    1991-01-01

    The Spacecraft Orbit Design and Analysis (SODA) computer program, Version 2.0, is discussed. SODA is a spaceflight mission planning system that consists of six program modules integrated around a common database and user interface. SODA runs on a VAX/VMS computer with an Evans and Sutherland PS300 graphics workstation. In the current version, three program modules produce an interactive three dimensional animation of one or more satellites in planetary orbit. Satellite visibility and sensor coverage capabilities are also provided. Circular and rectangular, off nadir, fixed and scanning sensors are supported. One module produces an interactive three dimensional animation of the solar system. Another module calculates cumulative satellite sensor coverage and revisit time for one or more satellites. Currently, Earth, Moon, and Mars systems are supported for all modules except the solar system module.

  14. Space Shuttle Orbiter - Leading edge structural design/analysis and material allowables

    NASA Technical Reports Server (NTRS)

    Johnson, D. W.; Curry, D. M.; Kelly, R. E.

    1986-01-01

    Reinforced Carbon-Carbon (RCC), a structural composite whose development was targeted for the high temperature reentry environments of reusable space vehicles, has successfully demonstrated that capability on the Space Shuttle Orbiter. Unique mechanical properties, particularly at elevated temperatures up to 3000 F, make this material ideally suited for the 'hot' regions of multimission space vehicles. Design allowable characterization testing, full-scale development and qualification testing, and structural analysis techniques will be presented herein that briefly chart the history of the RCC material from infancy to eventual multimission certification for the Orbiter. Included are discussions pertaining to the development of the design allowable data base, manipulation of the test data into usable forms, and the analytical verification process.

  15. Analysis of IUE data on V426 Ophiuchi - Outburst and orbital variability

    NASA Technical Reports Server (NTRS)

    Szkody, Paula; Mateo, Mario

    1988-01-01

    Time-resolved IUE spectra throughout two orbits of the dwarf nova V426 Oph during quiescence are presented. It is found that the visual and C IV fluxes remain relatively constant during both orbits, whereas the UV coninua and Mg II lines vary by 20-30 percent. The time scales of this variability are discussed. Analysis of other spectra at brighter optical magnitudes shows that the UV lags the optical during a probable rise to outburst, similar to the behavior of SS Cyg. The reddening of V426 Oph is determined to be E(B-V) = 0.1. The contribution of the white dwarf to the UV flux at quiescence is estimated to be 25 percent, based on the system parameters of Hessman (1988) and the period-temperature relation of Sion (1987).

  16. Spacecraft Orbit Design and Analysis (SODA), version 1.0 user's guide

    NASA Technical Reports Server (NTRS)

    Stallcup, Scott S.; Davis, John S.

    1989-01-01

    The Spacecraft Orbit Design and Analysis (SODA) computer program, Version 1.0 is described. SODA is a spaceflight mission planning system which consists of five program modules integrated around a common database and user interface. SODA runs on a VAX/VMS computer with an EVANS & SUTHERLAND PS300 graphics workstation. BOEING RIM-Version 7 relational database management system performs transparent database services. In the current version three program modules produce an interactive three dimensional (3D) animation of one or more satellites in planetary orbit. Satellite visibility and sensor coverage capabilities are also provided. One module produces an interactive 3D animation of the solar system. Another module calculates cumulative satellite sensor coverage and revisit time for one or more satellites. Currently Earth, Moon, and Mars systems are supported for all modules except the solar system module.

  17. Thermodynamic analysis and subscale modeling of space-based orbit transfer vehicle cryogenic propellant resupply

    NASA Technical Reports Server (NTRS)

    Defelice, David M.; Aydelott, John C.

    1987-01-01

    The resupply of the cryogenic propellants is an enabling technology for spacebased orbit transfer vehicles. As part of the NASA Lewis ongoing efforts in microgravity fluid management, thermodynamic analysis and subscale modeling techniques were developed to support an on-orbit test bed for cryogenic fluid management technologies. Analytical results have shown that subscale experimental modeling of liquid resupply can be used to validate analytical models when the appropriate target temperature is selected to relate the model to its prototype system. Further analyses were used to develop a thermodynamic model of the tank chilldown process which is required prior to the no-vent fill operation. These efforts were incorporated into two FORTRAN programs which were used to present preliminary analyticl results.

  18. Design and performance analysis of an aeromaneuvering orbital-transfer vehicle concept

    NASA Technical Reports Server (NTRS)

    Menees, G. P.

    1985-01-01

    Systems requirements for design-optimized, lateral-turn performance were determined for reusable, space-based applications and low-earth orbits involving large multiple plane-inclination changes. The aerothermodynamic analysis is the most advanced available for rarefied-hypersonic flow over lifting surfaces at incidence. The effects of leading-edge bluntness, low-density viscous phenomena, and finite-rate flow-field chemistry and surface catalysis are accounted for. The predicted aerothermal heating characteristics are correlated with thermal-control and flight-performance capabilities. The mission payload capacity for delivery, retrieval, and combined operations was determined for round-trip sorties extending to polar orbits. Recommendations are given for future design refinements. The results help to identify technology issues required to develop prototype operational vehicles.

  19. Independent Orbiter Assessment (IOA): Analysis of the purge, vent and drain subsystem

    NASA Technical Reports Server (NTRS)

    Bynum, M. C., III

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter PV and D (Purge, Vent and Drain) Subsystem hardware. The PV and D Subsystem controls the environment of unpressurized compartments and window cavities, senses hazardous gases, and purges Orbiter/ET Disconnect. The subsystem is divided into six systems: Purge System (controls the environment of unpressurized structural compartments); Vent System (controls the pressure of unpressurized compartments); Drain System (removes water from unpressurized compartments); Hazardous Gas Detection System (HGDS) (monitors hazardous gas concentrations); Window Cavity Conditioning System (WCCS) (maintains clear windows and provides pressure control of the window cavities); and External Tank/Orbiter Disconnect Purge System (prevents cryo-pumping/icing of disconnect hardware). Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Four of the sixty-two failure modes analyzed were determined as single failures which could result in the loss of crew or vehicle. A possible loss of mission could result if any of twelve single failures occurred. Two of the criticality 1/1 failures are in the Window Cavity Conditioning System (WCCS) outer window cavity, where leakage and/or restricted flow will cause failure to depressurize/repressurize the window cavity. Two criticality 1/1 failures represent leakage and/or restricted flow in the Orbiter/ET disconnect purge network which

  20. Analysis and optimization of an air-launch-to-orbit separation

    NASA Astrophysics Data System (ADS)

    Sohier, Henri; Piet-Lahanier, Helene; Farges, Jean-Loup

    2015-03-01

    In an air-launch-to-orbit, a space rocket is launched from a carrier aircraft. Air-launch-to-orbit appears as particularly interesting for nano- and microsatellites which are generally launched as secondary loads, that is, placed in the conventional launch vehicle's payload section with a larger primary satellite. In an air-launch-to-orbit, a small satellite can be launched alone as a primary load, away from a carrier aircraft, aboard a smaller rocket vehicle, and in doing so, benefit from more flexible dates and trajectories. One of the most important phases of the mission is the separation between the carrier aircraft and the space rocket. A flight simulator including a large number of factors of uncertainties has been especially developed to study the separation, and a safety criteria has been defined with respect to store collision avoidance. It is used for a sensitivity analysis and an optimization of the possible trajectories. The sensitivity analysis first requires a screening method to select unessential factors that can be held constant. The Morris method is amongst the most popular screening methods. It requires limited calculations, but may result in keeping constant an essential factor which would greatly affect the results of the sensitivity analysis. This paper shows that this risk can be important in spite of recent improvements of the Morris method. It presents an adaptation of this method which divides this risk by a factor of ten on a standard test function. It is based on the maximum of the elementary effects instead of their average. The method focuses the calculations on the factors with a low impact, checking the convergence of this set of factors, and uses two different factor variations instead of one. This adaptation of the Morris method is used to limit the amount of the air-launch-to-orbit simulations and simplify the uncertainty domain for analysis by Sobol's method. The aerodynamic perturbations due to wind, the parameters defining the

  1. Population pharmacokinetic and pharmacodynamic analysis in allergic diseases.

    PubMed

    Lovern, Mark; Sargentini-Maier, Maria-Laura; Otoul, Christian; Watelet, Jean-Baptiste

    2009-01-01

    In this chapter, we introduce the concepts and methodologies of population analysis as applied to analyzing pharmacokinetic and pharmacodynamic data. One of the key determining characteristics of the population approach is that through it, one seeks not only to characterize deterministic trends in the data, but also to identify and estimate the magnitudes of the important sources of variability within the data. The first section of this chapter provides an introduction to the primary concepts of, and motivation for, population modeling by way of a hypothetical case study. Then, the various methodologies that have been employed throughout the history of population analysis are described in further detail. Of these, the most commonly employed today is nonlinear mixed-effects (NLME) modeling. Finally, notable examples of the application of population PK and PK/PD modeling to treatments for allergies and asthma are discussed. Population PK models have frequently been used to extrapolate exposures to special populations, such as pediatrics, as well as to optimize treatment regimens and trial designs for these populations. Population PK/PD models have most frequently been applied to analyzing and interpreting data from wheal and flare trials, but are also becoming increasingly important in the analysis of PD data from monoclonal antibodies. PMID:19601723

  2. Orbit Optimization and Scattering Coefficient Analysis for the Proposed GLORIA System

    NASA Technical Reports Server (NTRS)

    Welch, Bryan

    2004-01-01

    This paper investigates the optimization of an orbit for a Low-Earth Orbiting (LEO) satellite for coastal coverage over Antarctic and United States shorelines as part of the Geostationary/Low-Earth Orbiting Radar Image Acquisition (GLORIA) System. Simulations over a range of orbital parameters are performed to determine the optimal orbit. Scattering coefficients are computed for the optimal orbit throughout the day and characterized to compare various scenarios for which link budget comparisons could then be made.

  3. Spin-Orbit Alignment of Exoplanet Systems: Ensemble Analysis Using Asteroseismology

    NASA Astrophysics Data System (ADS)

    Campante, T. L.; Lund, M. N.; Kuszlewicz, J. S.; Davies, G. R.; Chaplin, W. J.; Albrecht, S.; Winn, J. N.; Bedding, T. R.; Benomar, O.; Bossini, D.; Handberg, R.; Santos, A. R. G.; Van Eylen, V.; Basu, S.; Christensen-Dalsgaard, J.; Elsworth, Y. P.; Hekker, S.; Hirano, T.; Huber, D.; Karoff, C.; Kjeldsen, H.; Lundkvist, M. S.; North, T. S. H.; Silva Aguirre, V.; Stello, D.; White, T. R.

    2016-03-01

    The angle ψ between a planet’s orbital axis and the spin axis of its parent star is an important diagnostic of planet formation, migration, and tidal evolution. We seek empirical constraints on ψ by measuring the stellar inclination is via asteroseismology for an ensemble of 25 solar-type hosts observed with NASA’s Kepler satellite. Our results for is are consistent with alignment at the 2σ level for all stars in the sample, meaning that the system surrounding the red-giant star Kepler-56 remains as the only unambiguous misaligned multiple-planet system detected to date. The availability of a measurement of the projected spin-orbit angle λ for two of the systems allows us to estimate ψ. We find that the orbit of the hot Jupiter HAT-P-7b is likely to be retrograde (\\psi =116\\buildrel{\\circ}\\over{.} {4}-14.7+30.2), whereas that of Kepler-25c seems to be well aligned with the stellar spin axis (\\psi =12\\buildrel{\\circ}\\over{.} {6}-11.0+6.7). While the latter result is in apparent contradiction with a statement made previously in the literature that the multi-transiting system Kepler-25 is misaligned, we show that the results are consistent, given the large associated uncertainties. Finally, we perform a hierarchical Bayesian analysis based on the asteroseismic sample in order to recover the underlying distribution of ψ. The ensemble analysis suggests that the directions of the stellar spin and planetary orbital axes are correlated, as conveyed by a tendency of the host stars to display large values of inclination.

  4. Direct Detection and Orbital Analysis of the Exoplanets HR 8799 bcd from Archival 2005 Keck/NIRC2 Data

    NASA Astrophysics Data System (ADS)

    Currie, Thayne; Fukagawa, Misato; Thalmann, Christian; Matsumura, Soko; Plavchan, Peter

    2012-08-01

    We present previously unpublished 2005 July H-band coronagraphic data of the young, planet-hosting star HR 8799 from the newly released Keck/NIRC2 archive. Despite poor observing conditions, we detect three of the planets (HR 8799 bcd), two of them (HR 8799 bc) without advanced image processing. Comparing these data with previously published 1998-2011 astrometry and that from re-reduced 2010 October Keck data constrains the orbits of the planets. Analyzing the planets' astrometry separately, HR 8799 d's orbit is likely inclined at least 25° from face-on and the others may be on inclined orbits. For semimajor axis ratios consistent with a 4:2:1 mean-motion resonance, our analysis yields precise values for HR 8799 bcd's orbital parameters and strictly constrains the planets' eccentricities to be less than 0.18-0.3. However, we find no acceptable orbital solutions with this resonance that place the planets in face-on orbits; HR 8799 d shows the largest deviation from such orbits. Moreover, few orbits make HR 8799 d coplanar with b and c, whereas dynamical stability analyses used to constrain the planets' masses typically assume coplanar and/or face-on orbits. This Letter illustrates the significant science gain enabled with the release of the NIRC2 archive.

  5. Direct Detection and Orbit Analysis of the Exoplanets HR 8799 bcd from Archival 2005 Keck/NIRC2 Data

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Fukagawa, Misato; Thalmann, Christian; Matsumura, Soko; Plavchan, Peter

    2012-01-01

    We present previously unpublished July 2005 H-band coronagraphic data of the young, planet-hosting star HR 8799 from the newly-released Keck/NIRC2 archive. Despite poor observing conditions, we detect three of the planets (HR 8799 bcd), two of them (HR 8799 bc) without advanced image processing. Comparing these data with previously published 1998-2011 astrometry and that from re-reduced October 2010 Keck data constrains the orbits of the planets. Analyzing the planets' astrometry separately, HR 8799 d's orbit is likely inclined at least 25 deg from face-on and the others may be on in inclined orbits. For semimajor axis ratios consistent with a 4:2:1 mean-motion resonance our analysis yields precise values for HR 8799 bcd's orbital parameters and strictly constrains the planets' eccentricities to be less than 0.18-0.3. However, we find no acceptable orbital solutions with this resonance that place the planets in face-on orbits; HR 8799 d shows the largest deviation from such orbits. Moreover, few orbits make HR 8799 d coplanar with b and c, whereas dynamical stability analyses used to constrain the planets' masses typically assume coplanar and/or fare.on orbits. This paper illustrates the significant science gain enabled with the release of the NIRC2 archive.

  6. Independent Orbiter Assessment (IOA): Analysis of the atmospheric revitalization pressure control subsystem

    NASA Technical Reports Server (NTRS)

    Saiidi, M. J.; Duffy, R. E.; Mclaughlin, T. D.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Atmospheric Revitalization and Pressure Control Subsystem (ARPCS) are documented. The ARPCS hardware was categorized into the following subdivisions: (1) Atmospheric Make-up and Control (including the Auxiliary Oxygen Assembly, Oxygen Assembly, and Nitrogen Assembly); and (2) Atmospheric Vent and Control (including the Positive Relief Vent Assembly, Negative Relief Vent Assembly, and Cabin Vent Assembly). The IOA analysis process utilized available ARPCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  7. Independent Orbiter Assessment (IOA): Analysis of the displays and controls subsystem

    NASA Technical Reports Server (NTRS)

    Trahan, W. H.; Prust, E. E.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Displays and Controls (D and C) subsystem hardware. The function of the D and C hardware is to provide the crew with the monitor, command, and control capabilities required for management of all normal and contingency mission and flight operations. The D and C hardware for which failure modes analysis was performed consists of the following: Acceleration Indicator (G-METER); Head Up Display (HUD); Display Driver Unit (DDU); Alpha/Mach Indicator (AMI); Horizontal Situation Indicator (HSI); Attitude Director Indicator (ADI); Propellant Quantity Indicator (PQI); Surface Position Indicator (SPI); Altitude/Vertical Velocity Indicator (AVVI); Caution and Warning Assembly (CWA); Annunciator Control Assembly (ACA); Event Timer (ET); Mission Timer (MT); Interior Lighting; and Exterior Lighting. Each hardware item was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  8. Independent Orbiter Assessment (IOA): Analysis of the hydraulics/water spray boiler subsystem

    NASA Technical Reports Server (NTRS)

    Duval, J. D.; Davidson, W. R.; Parkman, William E.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results for the Orbiter Hydraulics/Water Spray Boiler Subsystem. The hydraulic system provides hydraulic power to gimbal the main engines, actuate the main engine propellant control valves, move the aerodynamic flight control surfaces, lower the landing gear, apply wheel brakes, steer the nosewheel, and dampen the external tank (ET) separation. Each hydraulic system has an associated water spray boiler which is used to cool the hydraulic fluid and APU lubricating oil. The IOA analysis process utilized available HYD/WSB hardware drawings, schematics and documents for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 430 failure modes analyzed, 166 were determined to be PCIs.

  9. Mission Analysis for LEO Microwave Power-Beaming Station in Orbital Launch of Microwave Lightcraft

    NASA Technical Reports Server (NTRS)

    Myrabo, L. N.; Dickenson, T.

    2005-01-01

    A detailed mission analysis study has been performed for a 1 km diameter, rechargeable satellite solar power station (SPS) designed to boost 20m diameter, 2400 kg Micr,oWave Lightcraft (MWLC) into low earth orbit (LEO) Positioned in a 476 km daily-repeating oi.bit, the 35 GHz microwave power station is configured like a spinning, thin-film bicycle wheel covered by 30% efficient sola cells on one side and billions of solid state microwave transmitter elements on the other, At the rim of this wheel are two superconducting magnets that can stor,e 2000 G.J of energy from the 320 MW, solar array over a period of several orbits. In preparation for launch, the entire station rotates to coarsely point at the Lightcraft, and then phases up using fine-pointing information sent from a beacon on-board the Lightcraft. Upon demand, the station transmits a 10 gigawatt microwave beam to lift the MWLC from the earth surface into LEO in a flight of several minutes duration. The mission analysis study was comprised of two parts: a) Power station assessment; and b) Analysis of MWLC dynamics during the ascent to orbit including the power-beaming relationships. The power station portion addressed eight critical issues: 1) Drag force vs. station orbital altitude; 2) Solar pressure force on the station; 3) Station orbital lifetime; 4) Feasibility of geo-magnetic re-boost; 5) Beta angle (i..e., sola1 alignment) and power station effective area relationship; 6) Power station percent time in sun vs, mission elapsed time; 7) Station beta angle vs.. charge time; 8) Stresses in station structures.. The launch dynamics portion examined four issues: 1) Ascent mission/trajecto1y profile; 2) MWLC/power-station mission geometry; 3) MWLC thrust angle vs. time; 4) Power station pitch rate during power beaming. Results indicate that approximately 0 58 N of drag force acts upon the station when rotated edge-on to project the minimum frontal area of 5000 sq m. An ion engine or perhaps an electrodynamic

  10. Assessing population exposure for landslide risk analysis using dasymetric cartography

    NASA Astrophysics Data System (ADS)

    Garcia, Ricardo A. C.; Oliveira, Sergio C.; Zezere, Jose L.

    2015-04-01

    Exposed Population is a major topic that needs to be taken into account in a full landslide risk analysis. Usually, risk analysis is based on an accounting of inhabitants number or inhabitants density, applied over statistical or administrative terrain units, such as NUTS or parishes. However, this kind of approach may skew the obtained results underestimating the importance of population, mainly in territorial units with predominance of rural occupation. Furthermore, the landslide susceptibility scores calculated for each terrain unit are frequently more detailed and accurate than the location of the exposed population inside each territorial unit based on Census data. These drawbacks are not the ideal setting when landslide risk analysis is performed for urban management and emergency planning. Dasymetric cartography, which uses a parameter or set of parameters to restrict the spatial distribution of a particular phenomenon, is a methodology that may help to enhance the resolution of Census data and therefore to give a more realistic representation of the population distribution. Therefore, this work aims to map and to compare the population distribution based on a traditional approach (population per administrative terrain units) and based on dasymetric cartography (population by building). The study is developed in the Region North of Lisbon using 2011 population data and following three main steps: i) the landslide susceptibility assessment based on statistical models independently validated; ii) the evaluation of population distribution (absolute and density) for different administrative territorial units (Parishes and BGRI - the basic statistical unit in the Portuguese Census); and iii) the dasymetric population's cartography based on building areal weighting. Preliminary results show that in sparsely populated administrative units, population density differs more than two times depending on the application of the traditional approach or the dasymetric

  11. Structural Analysis Peer Review for the Static Display of the Orbiter Atlantis at the Kennedy Space Center Visitors Center

    NASA Technical Reports Server (NTRS)

    Minute, Stephen A.

    2013-01-01

    Mr. Christopher Miller with the Kennedy Space Center (KSC) NASA Safety & Mission Assurance (S&MA) office requested the NASA Engineering and Safety Center's (NESC) technical support on March 15, 2012, to review and make recommendations on the structural analysis being performed for the Orbiter Atlantis static display at the KSC Visitor Center. The principal focus of the assessment was to review the engineering firm's structural analysis for lifting and aligning the orbiter and its static display configuration

  12. Independent Orbiter Assessment (IOA): Analysis of the electrical power distribution and control subsystem, volume 1

    NASA Technical Reports Server (NTRS)

    Schmeckpeper, K. R.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C) hardware. The EPD and C hardware performs the functions of distributing, sensing, and controlling 28 volt DC power and of inverting, distributing, sensing, and controlling 117 volt 400 Hz AC power to all Orbiter subsystems from the three fuel cells in the Electrical Power Generation (EPG) subsystem. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 1671 failure modes analyzed, 9 single failures were determined to result in loss of crew or vehicle. Three single failures unique to intact abort were determined to result in possible loss of the crew or vehicle. A possible loss of mission could result if any of 136 single failures occurred. Six of the criticality 1/1 failures are in two rotary and two pushbutton switches that control External Tank and Solid Rocket Booster separation. The other 6 criticality 1/1 failures are fuses, one each per Aft Power Control Assembly (APCA) 4, 5, and 6 and one each per Forward Power Control Assembly (FPCA) 1, 2, and 3, that supply power to certain Main Propulsion System (MPS) valves and Forward Reaction Control System (RCS) circuits.

  13. Evaluation of VIIRS SST fields through the analysis of overlap regions between consecutive orbits

    NASA Astrophysics Data System (ADS)

    Cayula, Jean-François P.; May, Douglas A.; Arnone, Robert A.; Vandermeulen, Ryan A.

    2015-05-01

    Full-swath Sea Surface Temperature (SST) derived from data acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on-board the Suomi-National Polar-orbiting Partnership (S-NPP) satellite produces significant overlap between consecutive orbits at all latitudes. In this study, we use those overlap regions to evaluate VIIRS SST, as inconsistencies between SST values from consecutive orbits are indications of likely degraded quality. The studies investigate two sources of inconsistencies: those resulting from the response of the SST equations when observing a scene from differing view angles and those caused by undetected data contamination. This study will present results for two VIIRS SST products: one from the Naval Oceanographic Office (NAVOCEANO), which is assimilated in the Navy Ocean Models, and the Advanced Clear-Sky Processor for Oceans (ACSPO) product from the National Oceanic and Atmospheric Administration (NOAA) Center for Satellite Applications and Research (STAR). Global statistics based on drifting buoys for both NAVOCEANO and NOAA products complete the analysis.

  14. An Analysis of Recent Major Breakups in he Low Earth Orbit Region

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Anz-Meador, P. D.

    2010-01-01

    Of the 190 known satellite breakups between 1961 and 2006, only one generated more than 500 cataloged fragments. The event was the explosion of the Pegasus Hydrazine Auxiliary Propulsion System in 1996, adding 713 fragments to the U.S. Satellite Catalog. Since the beginning of 2007; however, the near-Earth environment has been subjected to several major breakups, including the Fengyun-1C anti-satellite test and the explosion of Briz-M in 2007, the unusual breakup of Cosmos 2421 in 2008, and the collision between Iridium 33 and Cosmos 2251 in 2009. Combined, these events added more than 5000 large (> or equal 10 cm) fragments to the environment. Detailed analysis of the radar cross section measurements and orbit histories of the fragments from these major events reveals several unusual characteristics in their size and area-to-mass ratio distributions. The characteristics could be related to the material composition of the parent vehicles, the nature of the breakup, and the composition and physical property of the fragments. In addition, the majority of these fragments are expected to remain in orbit for at least decades. Their long-term impact to the environment is analyzed using the NASA orbital debris evolutionary model, LEGEND. Descriptions of these analyses and a summary are included in this paper.

  15. A method of orbital analysis for large-scale first-principles simulations

    SciTech Connect

    Ohwaki, Tsukuru; Otani, Minoru; Ozaki, Taisuke

    2014-06-28

    An efficient method of calculating the natural bond orbitals (NBOs) based on a truncation of the entire density matrix of a whole system is presented for large-scale density functional theory calculations. The method recovers an orbital picture for O(N) electronic structure methods which directly evaluate the density matrix without using Kohn-Sham orbitals, thus enabling quantitative analysis of chemical reactions in large-scale systems in the language of localized Lewis-type chemical bonds. With the density matrix calculated by either an exact diagonalization or O(N) method, the computational cost is O(1) for the calculation of NBOs associated with a local region where a chemical reaction takes place. As an illustration of the method, we demonstrate how an electronic structure in a local region of interest can be analyzed by NBOs in a large-scale first-principles molecular dynamics simulation for a liquid electrolyte bulk model (propylene carbonate + LiBF{sub 4})

  16. Mixed dentition analysis in a Moroccan population.

    PubMed

    Diagne, F; Diop-Ba, K; Ngom, P I; El Boury, O

    2004-12-01

    The aims of this study were to produce odontometric data for a Moroccan population, to test Tanaka and Johnston and Moyers methods, to derive regression equations and elaborate a specific orthodontic prediction table for Moroccan children. 50 dental casts of Moroccan students (25 males, 25 females, mean age 22.6 years sd 1.35) were used to perform measurements of the greatest mesiodistal widths of all mandibular and maxillary canines and premolars and mandibular incisors with an orthodontic calliper. Significant sexual dimorphism was found in tooth sizes (p = .001). The study revealed close relationships between the total mesiodistal widths of the mandibular permanent incisors and that of the maxillary and mandibular canines and premolars. The correlation coefficients (r) and the coefficient of determination (R2) were better sexes combined for the maxilla (r = 0.60 ; R2 = 0.36 ) and for the mandible (r = 0.61 ; R2= 0.37). The regression equations elaborated for males and females were used as a basis for establishing an orthodontic prediction table for Moroccan children. PMID:15853270

  17. Dynamic analysis of a parasite population model

    NASA Astrophysics Data System (ADS)

    Sibona, G. J.; Condat, C. A.

    2002-03-01

    We study the dynamics of a model that describes the competitive interaction between an invading species (a parasite) and its antibodies in an living being. This model was recently used to examine the dynamical competition between Tripanosoma cruzi and its antibodies during the acute phase of Chagas' disease. Depending on the antibody properties, the model yields three types of outcomes, corresponding, respectively, to healing, chronic disease, and host death. Here, we study the dynamics of the parasite-antibody interaction with the help of simulations, obtaining phase trajectories and phase diagrams for the system. We show that, under certain conditions, the size of the parasite inoculation can be crucial for the infection outcome and that a retardation in the stimulated production of an antibody species may result in the parasite gaining a definitive advantage. We also find a criterion for the relative sizes of the parameters that are required if parasite-generated decoys are indeed to help the invasion. Decoys may also induce a qualitatively different outcome: a limit cycle for the antibody-parasite population phase trajectories.

  18. Independent Orbiter Assessment (IOA): Analysis of the ascent thrust vector control actuator subsystem

    NASA Technical Reports Server (NTRS)

    Wilson, R. E.; Riccio, J. R.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Ascent Thrust Vector Control (ATVC) Actuator hardware are documented. The function of the Ascent Thrust Vector Control Actuators (ATVC) is to gimbal the main engines to provide for attitude and flight path control during ascent. During first stage flight, the SRB nozzles provide nearly all the steering. After SRB separation, the Orbiter is steered by gimbaling of its main engines. There are six electrohydraulic servoactuators, one pitch and one yaw for each of the three main engines. Each servoactuator is composed of four electrohydraulic servovalve assemblies, one second stage power spool valve assembly, one primary piston assembly and a switching valve. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Critical failures resulting in loss of ATVC were mainly due to loss of hydraulic fluid, fluid contamination and mechanical failures.

  19. Vibrational spectra and natural bond orbital analysis of organic crystal L-prolinium picrate

    NASA Astrophysics Data System (ADS)

    Edwin, Bismi; Amalanathan, M.; Hubert Joe, I.

    2012-10-01

    Vibrational spectral analysis and quantum chemical computations based on density functional theory (DFT) have been performed on the organic crystal L-prolinium picrate (LPP). The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers of LPP have been investigated using B3LYP method. The calculated molecular geometry has been compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA 4 program. The various intramolecular interactions confirming the biological activity of the compound have been exposed by natural bond orbital analysis. The distribution of Mulliken atomic charges and bending of natural hybrid orbitals associated with hydrogen bonding also reflects the presence of intramolecular hydrogen bonding thereby enhancing bioactivity. The analysis of the electron density of HOMO and LUMO gives an idea of the delocalization and low value of energy gap indicates electron transport in the molecule and thereby bioactivity. Vibrational analysis reveals the presence of strong O-H⋯O and N-H⋯O interaction between L-prolinium and picrate ions providing evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity.

  20. Study of space shuttle orbiter system management computer function. Volume 1: Analysis, baseline design

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A system analysis of the shuttle orbiter baseline system management (SM) computer function is performed. This analysis results in an alternative SM design which is also described. The alternative design exhibits several improvements over the baseline, some of which are increased crew usability, improved flexibility, and improved growth potential. The analysis consists of two parts: an application assessment and an implementation assessment. The former is concerned with the SM user needs and design functional aspects. The latter is concerned with design flexibility, reliability, growth potential, and technical risk. The system analysis is supported by several topical investigations. These include: treatment of false alarms, treatment of off-line items, significant interface parameters, and a design evaluation checklist. An in-depth formulation of techniques, concepts, and guidelines for design of automated performance verification is discussed.

  1. Data Acquisition, Management, and Analysis in Support of the Audiology and Hearing Conservation and the Orbital Debris Program Office

    NASA Technical Reports Server (NTRS)

    Dicken, Todd

    2012-01-01

    My internship at Johnson Space Center, Houston TX comprised of working simultaneously in the Space Life Science Directorate (Clinical Services Branch, SD3) in Audiology and Hearing Conservation and in the Astromaterials Research and Exploration Sciences Directorate in the Orbital Debris Program Office (KX). The purpose of the project done to support the Audiology and Hearing Conservation Clinic (AuHCon) is to organize and analyze auditory test data that has been obtained from tests conducted onboard the International Space Station (ISS) and in Johnson Space Center's clinic. Astronauts undergo a special type of auditory test called an On-Orbit Hearing Assessment (OOHA), which monitors hearing function while crewmembers are exposed to noise and microgravity during long-duration spaceflight. Data needed to be formatted to assist the Audiologist in studying, analyzing and reporting OOHA results from all ISS missions, with comparison to conventional preflight and post-flight audiometric test results of crewmembers. Orbital debris is the #1 threat to manned spacecraft; therefore NASA is investing in different measurement techniques to acquire information on orbital debris. These measurements are taken with telescopes in different parts of the world to acquire brightness variations over time, from which size, rotation rates and material information can be determined for orbital debris. Currently many assumptions are taken to resolve size and material from observed brightness, therefore a laboratory (Optical Measurement Center) is used to simulate the space environment and acquire information of known targets suited to best model the orbital debris population. In the Orbital Debris Program Office (ODPO) telescopic data were acquired and analyzed to better assess the orbital debris population.

  2. Acousto-optic signature analysis for inspection of the orbiter thermal protection tile bonds

    NASA Technical Reports Server (NTRS)

    Rodriguez, Julio G.; Tow, D. M.; Barna, B. A.

    1990-01-01

    The goal of this research is to develop a viable NDE technique for the inspection of orbiter thermal protection system (TPS) tile bonds. Phase 2, discussed here, concentrated on developing an empirical understanding of the bonded and unbonded vibration signatures of acreage tiles. Controlled experiments in the laboratory have provided useful information on the dynamic response of TPS tiles. It has been shown that several signatures are common to all the pedigree tiles. This degree of consistency in the tile-SIP (strain isolation pad) dynamic response proves that an unbond can be detected for a known tile and establish the basis for extending the analysis capability to arbitrary tiles for which there are no historical data. The field tests of the noncontacting laser acoustic sensor system, conducted at the Kennedy Space Center (KSC), investigated the vibrational environment of the Orbiter Processing Facility (OPF) and its effect on the measurement and analysis techniques being developed. The data collected showed that for orbiter locations, such as the body flap and elevon, the data analysis scheme, and/or the sensor, will require modification to accommodate the ambient motion. Several methods were identified for accomplishing this, and a solution is seen as readily achievable. It was established that the tile response was similar to that observed in the laboratory. Of most importance, however, is that the field environment will not affect the physics of the dynamic response that is related to bond condition. All of this information is fundamental to any future design and development of a prototype system.

  3. Acousto-optic signature analysis for inspection of the orbiter thermal protection tile bonds

    SciTech Connect

    Rodriguez, J.G.; Tow, D.M.; Barna, B.A.

    1989-01-01

    The goal of this research is to develop a viable, on contacting NDE technique for the inspection of orbiter thermal protection system (TPS) tile bonds. Phase 2, discussed here, concentrated on developing an empirical understanding of the b onded and unbonded vibration signatures of acreage tiles. Controlled experiments in the laboratory have provided useful information on the dynamic response of TPS tiles. It has been shown that several signatures are common to all the pedigree'' tiles. This degree of consistency in the tile-SIP (strain isolation pad) dynamic response proves that an unbond can be detected for a known tile and established the basis for extending the analysis capability to arbitrary tiles for which there are no historical data. The field tests of the noncontacting laser acoustic sensor system, conducted at Kennedy Space Center (KSC), investigated the vibrational environment of the Orbiter Processing Facility (OPF) and its effect on the measurement and analysis techniques being developed. The data collected showed that for orbiter locations, such as the body flap and elevon, the data analysis scheme, and/or the sensor, will require modification to accommodate the ambient motion. Several methods have been identified for accomplishing this, and a solution is seen as readily achievable. It was established that the tile response was similar to that observed in the laboratory. Of most importance, however, is that the field environment will not affect the physics of the dynamic response that is related to bond condition. All of this information is fundamental to any future design and development of a prototype system. 2 refs., 9 figs.

  4. Demographics of reintroduced populations: estimation, modeling, and decision analysis

    USGS Publications Warehouse

    Converse, Sarah J.; Moore, Clinton T.; Armstrong, Doug P.

    2013-01-01

    Reintroduction can be necessary for recovering populations of threatened species. However, the success of reintroduction efforts has been poorer than many biologists and managers would hope. To increase the benefits gained from reintroduction, management decision making should be couched within formal decision-analytic frameworks. Decision analysis is a structured process for informing decision making that recognizes that all decisions have a set of components—objectives, alternative management actions, predictive models, and optimization methods—that can be decomposed, analyzed, and recomposed to facilitate optimal, transparent decisions. Because the outcome of interest in reintroduction efforts is typically population viability or related metrics, models used in decision analysis efforts for reintroductions will need to include population models. In this special section of the Journal of Wildlife Management, we highlight examples of the construction and use of models for informing management decisions in reintroduced populations. In this introductory contribution, we review concepts in decision analysis, population modeling for analysis of decisions in reintroduction settings, and future directions. Increased use of formal decision analysis, including adaptive management, has great potential to inform reintroduction efforts. Adopting these practices will require close collaboration among managers, decision analysts, population modelers, and field biologists.

  5. Counterpoise-corrected interaction energy analysis based on the fragment molecular orbital scheme

    NASA Astrophysics Data System (ADS)

    Okiyama, Yoshio; Fukuzawa, Kaori; Yamada, Haruka; Mochizuki, Yuji; Nakano, Tatsuya; Tanaka, Shigenori

    2011-06-01

    Basis set superposition error (BSSE) correction with counterpoise (CP) procedure under the environmental electrostatic potential is newly introduced to interfragment interaction energy (IFIE), which is important for interaction analysis in the fragment molecular orbital method. The CP correction for IFIE is applied to a stacked dimer of base pair and a protein-ligand complex of estrogen receptor and 17β-estradiol with scaled third-order Møller-Plesset perturbation theory. The BSSEs amount to about quarter of IFIE for hydrogen-bonding and electrostatic interactions and half or even more for dispersion interactions. Estimation of IFIE with the CP correction is therefore preferred for the quantitative discussion.

  6. Supporting flight data analysis for Space Shuttle Orbiter Experiments at NASA Ames Research Center

    NASA Technical Reports Server (NTRS)

    Green, M. J.; Budnick, M. P.; Yang, L.; Chiasson, M. P.

    1983-01-01

    The Space Shuttle Orbiter Experiments program in responsible for collecting flight data to extend the research and technology base for future aerospace vehicle design. The Infrared Imagery of Shuttle (IRIS), Catalytic Surface Effects, and Tile Gap Heating experiments sponsored by Ames Research Center are part of this program. The paper describes the software required to process the flight data which support these experiments. In addition, data analysis techniques, developed in support of the IRIS experiment, are discussed. Using the flight data base, the techniques have provided information useful in analyzing and correcting problems with the experiment, and in interpreting the IRIS image obtained during the entry of the third Shuttle mission.

  7. Supporting flight data analysis for Space Shuttle Orbiter experiments at NASA Ames Research Center

    NASA Technical Reports Server (NTRS)

    Green, M. J.; Budnick, M. P.; Yang, L.; Chiasson, M. P.

    1983-01-01

    The space shuttle orbiter experiments program is responsible for collecting flight data to extend the research and technology base for future aerospace vehicle design. The infrared imagery of shuttle (IRIS), catalytic surface effects, and tile gap heating experiments sponsored by Ames Research Center are part of this program. The software required to process the flight data which support these experiments is described. In addition, data analysis techniques, developed in support of the IRIS experiment, are discussed. Using the flight data base, the techniques provide information useful in analyzing and correcting problems with the experiment, and in interpreting the IRIS image obtained during the entry of the third shuttle mission.

  8. Use of MSC/NASTRAN for the thermal analysis of the Space Shuttle Orbiter braking system

    NASA Technical Reports Server (NTRS)

    Shu, James; Mccann, David

    1987-01-01

    A description is given of the thermal modeling and analysis effort being conducted to investigate the transient temperature and thermal stress characteristics of the Space Shuttle Orbiter brake components and subsystems. Models are constructed of the brake stator as well as of the entire brake assembly to analyze the temperature distribution and thermal stress during the landing and braking process. These investigations are carried out on a UNIVAC computer system with MSC/NASTRAN Version 63. Analytical results and solution methods are presented and comparisons are made with SINDA results.

  9. Integrated orbital servicing study for low-cost payload programs. Volume 2: Technical and cost analysis

    NASA Technical Reports Server (NTRS)

    Cody, E. R.; Deats, C. L.; Derocher, W. L., Jr.; Kyrias, G. M.; Snodgrass, M. R.; Sosnay, R. D.; Spencer, R. A.; Wudell, A. E.

    1975-01-01

    Orbital maintenance concepts were examined in an effort to determine a cost effective orbital maintenance system compatible with the space transportation system. An on-orbit servicer maintenance system is recommended as the most cost effective system. A pivoting arm on-orbit servicer was selected and a preliminary design was prepared. It is indicated that orbital maintenance does not have any significant impact on the space transportation system.

  10. Sensitivity analysis of periodic matrix population models.

    PubMed

    Caswell, Hal; Shyu, Esther

    2012-12-01

    Periodic matrix models are frequently used to describe cyclic temporal variation (seasonal or interannual) and to account for the operation of multiple processes (e.g., demography and dispersal) within a single projection interval. In either case, the models take the form of periodic matrix products. The perturbation analysis of periodic models must trace the effects of parameter changes, at each phase of the cycle, on output variables that are calculated over the entire cycle. Here, we apply matrix calculus to obtain the sensitivity and elasticity of scalar-, vector-, or matrix-valued output variables. We apply the method to linear models for periodic environments (including seasonal harvest models), to vec-permutation models in which individuals are classified by multiple criteria, and to nonlinear models including both immediate and delayed density dependence. The results can be used to evaluate management strategies and to study selection gradients in periodic environments. PMID:23316494

  11. The constrained space orbital variation analysis for periodic ab initio calculations

    SciTech Connect

    Cruz Hernandez, N.; Zicovich-Wilson, Claudio Marcelo; Fdez Sanz, Javier

    2006-05-21

    The constrained space orbital variation (CSOV) method for the analysis of the interaction energy has been implemented in the periodic ab initio CRYSTAL03 code. The method allows for the partition of the energy of two interacting chemical entities, represented in turn by periodic models, into contributions which account for electrostatic effects, mutual polarization and charge transfer. The implementation permits one to carry out the analysis both at the Hartree-Fock and density functional theory levels, where in the latter the most popular exchange-correlation functionals can be used. As an illustrating example, the analysis of the interaction between CO and the MgO (001) surface has been considered. As expected by the almost fully ionic character of the support, our periodic CSOV results, in general agree with those previously obtained using the embedded cluster approach, showing the reliability of the present implementation.

  12. Use of an engineering data management system in the analysis of Space Shuttle Orbiter tiles

    NASA Technical Reports Server (NTRS)

    Giles, G. L.; Vallas, M.

    1981-01-01

    This paper demonstrates the use of an engineering data management system to facilitate the extensive stress analyses of the Space Shuttle Orbiter thermal protection system. Descriptions are given of the approach and methods used (1) to gather, organize, and store the data, (2) to query data interactively, (3) to generate graphic displays of the data, and (4) to access, transform, and prepare the data for input to a stress analysis program. The relational information management system was found to be well suited to the tile analysis problem because information related to many separate tiles could be accessed individually from a data base having a natural organization from an engineering viewpoint. The flexible user features of the system facilitated changes in data content and organization which occurred during the development and refinement of the tile analysis procedure. Additionally, the query language supported retrieval of data to satisfy a variety of user-specified conditions.

  13. Periodic orbit analysis of a system with continuous symmetry—A tutorial

    NASA Astrophysics Data System (ADS)

    Budanur, Nazmi Burak; Borrero-Echeverry, Daniel; Cvitanović, Predrag

    2015-07-01

    Dynamical systems with translational or rotational symmetry arise frequently in studies of spatially extended physical systems, such as Navier-Stokes flows on periodic domains. In these cases, it is natural to express the state of the fluid in terms of a Fourier series truncated to a finite number of modes. Here, we study a 4-dimensional model with chaotic dynamics and SO(2) symmetry similar to those that appear in fluid dynamics problems. A crucial step in the analysis of such a system is symmetry reduction. We use the model to illustrate different symmetry-reduction techniques. The system's relative equilibria are conveniently determined by rewriting the dynamics in terms of a symmetry-invariant polynomial basis. However, for the analysis of its chaotic dynamics, the "method of slices," which is applicable to very high-dimensional problems, is preferable. We show that a Poincaré section taken on the "slice" can be used to further reduce this flow to what is for all practical purposes a unimodal map. This enables us to systematically determine all relative periodic orbits and their symbolic dynamics up to any desired period. We then present cycle averaging formulas adequate for systems with continuous symmetry and use them to compute dynamical averages using relative periodic orbits. The convergence of such computations is discussed.

  14. Periodic orbit analysis of a system with continuous symmetry—A tutorial

    SciTech Connect

    Budanur, Nazmi Burak Cvitanović, Predrag; Borrero-Echeverry, Daniel

    2015-07-15

    Dynamical systems with translational or rotational symmetry arise frequently in studies of spatially extended physical systems, such as Navier-Stokes flows on periodic domains. In these cases, it is natural to express the state of the fluid in terms of a Fourier series truncated to a finite number of modes. Here, we study a 4-dimensional model with chaotic dynamics and SO(2) symmetry similar to those that appear in fluid dynamics problems. A crucial step in the analysis of such a system is symmetry reduction. We use the model to illustrate different symmetry-reduction techniques. The system's relative equilibria are conveniently determined by rewriting the dynamics in terms of a symmetry-invariant polynomial basis. However, for the analysis of its chaotic dynamics, the “method of slices,” which is applicable to very high-dimensional problems, is preferable. We show that a Poincaré section taken on the 'slice' can be used to further reduce this flow to what is for all practical purposes a unimodal map. This enables us to systematically determine all relative periodic orbits and their symbolic dynamics up to any desired period. We then present cycle averaging formulas adequate for systems with continuous symmetry and use them to compute dynamical averages using relative periodic orbits. The convergence of such computations is discussed.

  15. Analysis of Population Substructure in Two Sympatric Populations of Gran Chaco, Argentina

    PubMed Central

    Sevini, Federica; Yao, Daniele Yang; Lomartire, Laura; Barbieri, Annalaura; Vianello, Dario; Ferri, Gianmarco; Moretti, Edgardo; Dasso, Maria Cristina; Garagnani, Paolo; Pettener, Davide; Franceschi, Claudio; Luiselli, Donata; Franceschi, Zelda Alice

    2013-01-01

    Sub-population structure and intricate kinship dynamics might introduce biases in molecular anthropology studies and could invalidate the efforts to understand diseases in highly admixed populations. In order to clarify the previously observed distribution pattern and morbidity of Chagas disease in Gran Chaco, Argentina, we studied two populations (Wichí and Criollos) recruited following an innovative bio-cultural model considering their complex cultural interactions. By reconstructing the genetic background and the structure of these two culturally different populations, the pattern of admixture, the correspondence between genealogical and genetic relationships, this integrated perspective had the power to validate data and to link the gap usually relying on a singular discipline. Although Wichí and Criollos share the same area, these sympatric populations are differentiated from the genetic point of view as revealed by Non Recombinant Y Chromosome genotyping resulting in significantly high Fst values and in a lower genetic variability in the Wichí population. Surprisingly, the Amerindian and the European components emerged with comparable amounts (20%) among Criollos and Wichí respectively. The detailed analysis of mitochondrial DNA showed that the two populations have as much as 87% of private haplotypes. Moreover, from the maternal perspective, despite a common Amerindian origin, an Andean and an Amazonian component emerged in Criollos and in Wichí respectively. Our approach allowed us to highlight that quite frequently there is a discrepancy between self-reported and genetic kinship. Indeed, if self-reported identity and kinship are usually utilized in population genetics as a reliable proxy for genetic identity and parental relationship, in our model populations appear to be the result not only and not simply of the genetic background but also of complex cultural determinants. This integrated approach paves the way to a rigorous reconstruction of

  16. Analysis of population substructure in two sympatric populations of Gran Chaco, Argentina.

    PubMed

    Sevini, Federica; Yao, Daniele Yang; Lomartire, Laura; Barbieri, Annalaura; Vianello, Dario; Ferri, Gianmarco; Moretti, Edgardo; Dasso, Maria Cristina; Garagnani, Paolo; Pettener, Davide; Franceschi, Claudio; Luiselli, Donata; Franceschi, Zelda Alice

    2013-01-01

    Sub-population structure and intricate kinship dynamics might introduce biases in molecular anthropology studies and could invalidate the efforts to understand diseases in highly admixed populations. In order to clarify the previously observed distribution pattern and morbidity of Chagas disease in Gran Chaco, Argentina, we studied two populations (Wichí and Criollos) recruited following an innovative bio-cultural model considering their complex cultural interactions. By reconstructing the genetic background and the structure of these two culturally different populations, the pattern of admixture, the correspondence between genealogical and genetic relationships, this integrated perspective had the power to validate data and to link the gap usually relying on a singular discipline. Although Wichí and Criollos share the same area, these sympatric populations are differentiated from the genetic point of view as revealed by Non Recombinant Y Chromosome genotyping resulting in significantly high Fst values and in a lower genetic variability in the Wichí population. Surprisingly, the Amerindian and the European components emerged with comparable amounts (20%) among Criollos and Wichí respectively. The detailed analysis of mitochondrial DNA showed that the two populations have as much as 87% of private haplotypes. Moreover, from the maternal perspective, despite a common Amerindian origin, an Andean and an Amazonian component emerged in Criollos and in Wichí respectively. Our approach allowed us to highlight that quite frequently there is a discrepancy between self-reported and genetic kinship. Indeed, if self-reported identity and kinship are usually utilized in population genetics as a reliable proxy for genetic identity and parental relationship, in our model populations appear to be the result not only and not simply of the genetic background but also of complex cultural determinants. This integrated approach paves the way to a rigorous reconstruction of

  17. Agriculture, population growth, and statistical analysis of the radiocarbon record

    PubMed Central

    Zahid, H. Jabran; Robinson, Erick; Kelly, Robert L.

    2016-01-01

    The human population has grown significantly since the onset of the Holocene about 12,000 y ago. Despite decades of research, the factors determining prehistoric population growth remain uncertain. Here, we examine measurements of the rate of growth of the prehistoric human population based on statistical analysis of the radiocarbon record. We find that, during most of the Holocene, human populations worldwide grew at a long-term annual rate of 0.04%. Statistical analysis of the radiocarbon record shows that transitioning farming societies experienced the same rate of growth as contemporaneous foraging societies. The same rate of growth measured for populations dwelling in a range of environments and practicing a variety of subsistence strategies suggests that the global climate and/or endogenous biological factors, not adaptability to local environment or subsistence practices, regulated the long-term growth of the human population during most of the Holocene. Our results demonstrate that statistical analyses of large ensembles of radiocarbon dates are robust and valuable for quantitatively investigating the demography of prehistoric human populations worldwide. PMID:26699457

  18. Agriculture, population growth, and statistical analysis of the radiocarbon record.

    PubMed

    Zahid, H Jabran; Robinson, Erick; Kelly, Robert L

    2016-01-26

    The human population has grown significantly since the onset of the Holocene about 12,000 y ago. Despite decades of research, the factors determining prehistoric population growth remain uncertain. Here, we examine measurements of the rate of growth of the prehistoric human population based on statistical analysis of the radiocarbon record. We find that, during most of the Holocene, human populations worldwide grew at a long-term annual rate of 0.04%. Statistical analysis of the radiocarbon record shows that transitioning farming societies experienced the same rate of growth as contemporaneous foraging societies. The same rate of growth measured for populations dwelling in a range of environments and practicing a variety of subsistence strategies suggests that the global climate and/or endogenous biological factors, not adaptability to local environment or subsistence practices, regulated the long-term growth of the human population during most of the Holocene. Our results demonstrate that statistical analyses of large ensembles of radiocarbon dates are robust and valuable for quantitatively investigating the demography of prehistoric human populations worldwide. PMID:26699457

  19. The design and analysis of a double swivel toggle release mechanism for the Orbiter stabilized payload deployment system

    NASA Technical Reports Server (NTRS)

    King, Guy L.; Tsai, Ted

    1989-01-01

    The NASA Stabilized Payload Deployment System (SPDS) is discussed. The lightweight and heavy-duty system rolls payloads over the orbiter's side rather than ejecting them upward. The system will enhance the orbiter capability of carrying larger and heavier payloads. The design, function, and analysis of a new three-pin double swivel toggle release mechanism which is crucial to the successful deployment of the SPDS are described.

  20. Origin of orbital debris impacts on LDEF's trailing surfaces

    NASA Astrophysics Data System (ADS)

    Kessler, Donald J.

    1993-04-01

    A model was developed to determine the origin of orbital impacts measured on the training surfaces of LDEF. The model calculates the expected debris impact crater distribution around LDEF as a function of debris orbital parameters. The results show that only highly elliptical, low inclination orbits could be responsible for these impacts. The most common objects left in this type of orbit are orbital transfer stages used by the U.S. and ESA to place payloads into geosynchronous orbit. Objects in this type of orbit are difficult to catalog by the U.S. Space Command; consequently there are independent reasons to believe that the catalog does not adequately represent this population. This analysis concludes that the relative number of cataloged objects with highly elliptical, low inclination orbits must be increased by a factor of 20 to be consistent with the LDEF data.

  1. Conformational analysis of methylphenidate: comparison of molecular orbital and molecular mechanics methods.

    PubMed

    Gilbert, Kathleen M; Skawinski, William J; Misra, Milind; Paris, Kristina A; Naik, Neelam H; Buono, Ronald A; Deutsch, Howard M; Venanzi, Carol A

    2004-11-01

    Methylphenidate (MP) binds to the cocaine binding site on the dopamine transporter and inhibits reuptake of dopamine, but does not appear to have the same abuse potential as cocaine. This study, part of a comprehensive effort to identify a drug treatment for cocaine abuse, investigates the effect of choice of calculation technique and of solvent model on the conformational potential energy surface (PES) of MP and a rigid methylphenidate (RMP) analogue which exhibits the same dopamine transporter binding affinity as MP. Conformational analysis was carried out by the AM1 and AM1/SM5.4 semiempirical molecular orbital methods, a molecular mechanics method (Tripos force field with the dielectric set equal to that of vacuum or water) and the HF/6-31G* molecular orbital method in vacuum phase. Although all three methods differ somewhat in the local details of the PES, the general trends are the same for neutral and protonated MP. In vacuum phase, protonation has a distinctive effect in decreasing the regions of space available to the local conformational minima. Solvent has little effect on the PES of the neutral molecule and tends to stabilize the protonated species. The random search (RS) conformational analysis technique using the Tripos force field was found to be capable of locating the minima found by the molecular orbital methods using systematic grid search. This suggests that the RS/Tripos force field/vacuum phase protocol is a reasonable choice for locating the local minima of MP. However, the Tripos force field gave significantly larger phenyl ring rotational barriers than the molecular orbital methods for MP and RMP. For both the neutral and protonated cases, all three methods found the phenyl ring rotational barriers for the RMP conformers/invertamers (denoted as cte, tte, and cta) to be: cte, tte > MP > cta. Solvation has negligible effect on the phenyl ring rotational barrier of RMP. The B3LYP/6-31G* density functional method was used to calculate the

  2. Fixed point sensitivity analysis of interacting structured populations.

    PubMed

    Barabás, György; Meszéna, Géza; Ostling, Annette

    2014-03-01

    Sensitivity analysis of structured populations is a useful tool in population ecology. Historically, methodological development of sensitivity analysis has focused on the sensitivity of eigenvalues in linear matrix models, and on single populations. More recently there have been extensions to the sensitivity of nonlinear models, and to communities of interacting populations. Here we derive a fully general mathematical expression for the sensitivity of equilibrium abundances in communities of interacting structured populations. Our method yields the response of an arbitrary function of the stage class abundances to perturbations of any model parameters. As a demonstration, we apply this sensitivity analysis to a two-species model of ontogenetic niche shift where each species has two stage classes, juveniles and adults. In the context of this model, we demonstrate that our theory is quite robust to violating two of its technical assumptions: the assumption that the community is at a point equilibrium and the assumption of infinitesimally small parameter perturbations. Our results on the sensitivity of a community are also interpreted in a niche theoretical context: we determine how the niche of a structured population is composed of the niches of the individual states, and how the sensitivity of the community depends on niche segregation. PMID:24368160

  3. Analysis of the effects of mean local node-crossing time on the evolution of Sun-synchronous orbits

    NASA Technical Reports Server (NTRS)

    Jordan, P.; Blaes, V.; Roszman, L.; Cooley, J.

    1993-01-01

    An investigation of the effect of mean local node-crossing time on the evolution of Sun-synchronous orbits was undertaken during Phase-A orbit analysis for the National Oceanic and Atmospheric Administration (NOAA) O,P,Q environmental spacecraft. That analysis added to the growing body of evidence that individual Sun-synchronous missions, at differing node-crossing times, experience nodal drift rates that can differ in both magnitude and direction. A Sun-synchronous orbit is obtained by means of a nodal drift rate approximating the 0.9856-degree-per-day apparent precession of the position of the mean Sun. This drift rate is achieved through the interaction of the orbital semimajor axis and inclination in Earth's geopotential field. Influencing perturbations include atmospheric drag and, most important, the effects of solar gravitation on inclination. The present analysis examines a series of Sun-synchronous orbits with mean local node-crossing times at 1-hour intervals from 6 a.m. to 6 p.m. It considers the fixed geometry of each orbital plane with respect to both the Sun and the diurnal atmospheric bulge, then analyzes the influence of these features upon the evolution of the semimajor axix and inclination and thus upon the rate of the nodal drift in the course of 1 year.

  4. Use of an engineering data management system in the analysis of space shuttle orbiter tiles

    NASA Technical Reports Server (NTRS)

    Giles, G. L.; Vallas, M.

    1981-01-01

    The use of an engineering data management system to facilitate the extensive stress analyses of the space shuttle orbiter thermal protection system is demonstrated. The methods used to gather, organize, and store the data; to query data interactively; to generate graphic displays of the data; and to access, transform, and prepare the data for input to a stress analysis program are described. Information related to many separate tiles can be accessed individually from the data base which has a natural organization from an engineering viewpoint. The flexible user features of the system facilitate changes in data content and organization which occur during the development and refinement of the tile analysis procedure. Additionally, the query language supports retrieval of data to satisfy a variety of user-specified conditions.

  5. Periodic orbits analysis of the form factor: from ballistic to diffusive systems

    NASA Astrophysics Data System (ADS)

    Agam, Oded; Fishman, Shmuel

    1996-05-01

    The energy level correlator K(s) and the form factor 0305-4470/29/9/016/img1 are calculated for a hypercubic billiard with small hyperspheres placed at random in its interior. Various regimes, characterized by the elastic mean free path l, resulting from the scattering on impurities, are identified. The analysis extends from the ballistic regime, where l is much larger than the size of the system, via intermediate regimes, to the diffusive regime, where l is much smaller than its size. Semiclassical expressions for the density of states of chaotic and integrable systems in terms of classical periodic orbits are used. The diagonal approximation for 0305-4470/29/9/016/img1 is made for short times, while non-perturbative methods are used for long times. The analysis makes use of analytic properties of classical dynamical zeta function associated with the Perron - Frobenius operator. The general features are relevant for mesoscopic systems.

  6. Real-time automated failure analysis for on-orbit operations

    NASA Technical Reports Server (NTRS)

    Kirby, Sarah; Lauritsen, Janet; Pack, Ginger; Ha, Anhhoang; Jowers, Steven; Mcnenny, Robert; Truong, The; Dell, James

    1993-01-01

    A system which is to provide real-time failure analysis support to controllers at the NASA Johnson Space Center Control Center Complex (CCC) for both Space Station and Space Shuttle on-orbit operations is described. The system employs monitored systems' models of failure behavior and model evaluation algorithms which are domain-independent. These failure models are viewed as a stepping stone to more robust algorithms operating over models of intended function. The described system is designed to meet two sets of requirements. It must provide a useful failure analysis capability enhancement to the mission controller. It must satisfy CCC operational environment constraints such as cost, computer resource requirements, verification, and validation. The underlying technology and how it may be used to support operations is also discussed.

  7. LANDSAT-D MSS/TM tuned orbital jitter analysis model LDS900

    NASA Technical Reports Server (NTRS)

    Pollak, T. E.

    1981-01-01

    The final LANDSAT-D orbital dynamic math model (LSD900), comprised of all test validated substructures, was used to evaluate the jitter response of the MSS/TM experiments. A dynamic forced response analysis was performed at both the MSS and TM locations on all structural modes considered (thru 200 Hz). The analysis determined the roll angular response of the MSS/TM experiments to improve excitation generated by component operation. Cross axis and cross experiment responses were also calculated. The excitations were analytically represented by seven and nine term Fourier series approximations, for the MSS and TM experiment respectively, which enabled linear harmonic solution techniques to be applied to response calculations. Single worst case jitter was estimated by variations of the eigenvalue spectrum of model LSD 900. The probability of any worst case mode occurrence was investigated.

  8. Independent Orbiter Assessment (IOA): Analysis of the rudder/speed brake subsystem

    NASA Technical Reports Server (NTRS)

    Wilson, R. E.; Riccio, J. R.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Rudder/Speedbrake Actuation Mechanism is documented. The function of the Rudder/Speedbrake (RSB) is to provide directional control and to provide a means of energy control during entry. The system consists of two panels on a vertical hinge mounted on the aft part of the vertical stabilizer. These two panels move together to form a rudder but split apart to make a speedbrake. The Rudder/Speedbrake Actuation Mechanism consists of the following elements: (1) Power Drive Unit (PDU) which is composed of hydraulic valve module and a hydraulic motor-powered gearbox which contains differentials and mixer gears to provide PDU torque output; (2) four geared rotary actuators which apply the PDU generated torque to the rudder/speedbrake panels; and (3) ten torque shafts which join the PDU to the rotary actuators and interconnect the four rotary actuators. Each level of hardware was evaluated and analyzed for possible failures and causes. Criticality was assigned based upon the severity of the effect for each failure mode. Critical RSB failures which result in potential loss of vehicle control were mainly due to loss of hydraulic fluid, fluid contaminators, and mechanical failures in gears and shafts.

  9. Mission analysis data for inclined geosynchronous orbits, part 2. Appendix A: Bibliography

    NASA Technical Reports Server (NTRS)

    1980-01-01

    A bibliography of papers and reports on geosynchronous orbits, as well as background papers concerned with the fundamentals of orbital mechanics is presented. A listing of computer programs developed for this study is included.

  10. Preliminary assessment of aerial photography techniques for canvasback population analysis

    USGS Publications Warehouse

    Munro, R.E.; Trauger, D.L.

    1976-01-01

    Recent intensive research on the canvasback has focused attention on the need for more precise estimates of population parameters. During the 1972-75 period, various types of aerial photographing equipment were evaluated to determine the problems and potentials for employing these techniques in appraisals of canvasback populations. The equipment and procedures available for automated analysis of aerial photographic imagery were also investigated. Serious technical problems remain to be resolved, but some promising results were obtained. Final conclusions about the feasibility of operational implementation await a more rigorous analysis of the data collected.

  11. Important population viability analysis parameters for giant pandas (Aliuropoda melanoleuca).

    PubMed

    Gong, Minghao; Song, Yanling; Yang, Zhisong; Lin, Chen

    2012-06-01

    Population viability analysis (PVA) is a tool to evaluate the risk of extinction for endangered species and aid conservation decision-making. The quality of PVA output is dependent on parameters related to population dynamics and life-history; however, it has been difficult to collect this information for the giant panda (Aliuropoda melanoleuca), a rare and endangered mammal native to China, confined to some 30 fragmented habitat patches. Since giant pandas are long-lived, mature late, have lower reproductive rates, and show little sexual dimorphism, obtaining data to perform adequate PVA has been difficult. Here, we develop a parameter sensitivity index by modeling the dynamics of six giant panda populations in the Minshan Mountains, in order to determine the parameters most influential to giant panda populations. Our data shows that the giant panda populations are most sensitive to changes in four female parameters: initial breeding age, reproductive rate, mortality rate between age 0 and 1, and mortality rate of adults. The parameter sensitivity index strongly correlated with initial population size, as smaller populations were more sensitive to changes in these four variables. This model suggests that demographic parameters of females have more influence on the results of PVA, indicating that females may play a more important role in giant panda population dynamics than males. Consequently, reintroduction of female individuals to a small giant panda population should be a high priority for conservation efforts. Our findings form a technical basis for the coming program of giant panda reintroduction, and inform which parameters are crucial to successfully and feasibly monitoring wild giant panda populations. PMID:22653866

  12. Mission Life Thermal Analysis and Environment Correlation for the Lunar Reconnaissance Orbiter

    NASA Technical Reports Server (NTRS)

    Garrison, Matthew B.; Peabody, Hume

    2012-01-01

    Standard thermal analysis practices include stacking worst-case conditions including environmental heat loads, thermo-optical properties and orbital beta angles. This results in the design being driven by a few bounding thermal cases, although those cases may only represent a very small portion of the actual mission life. The NASA Goddard Space Flight Center Thermal Branch developed a procedure to predict the flight temperatures over the entire mission life, assuming a known beta angle progression, variation in the thermal environment, and a degradation rate in the coatings. This was applied to the Global Precipitation Measurement core spacecraft. In order to assess the validity of this process, this work applies the similar process to the Lunar Reconnaissance Orbiter. A flight-correlated thermal model was exercised to give predictions of the thermal performance over the mission life. These results were then compared against flight data from the first two years of the spacecraft s use. This is used to validate the process and to suggest possible improvements for future analyses.

  13. An analysis of ullage heat transfer in the orbital refueling system

    NASA Technical Reports Server (NTRS)

    Kauffman, D.

    1986-01-01

    The Orbital Refueling System was an experiment flown on Shuttle Mission STS 41-G in October, 1984. Liquid hydrazine fuel was transferred back and forth from one spherical bladder tank to another using pressurized nitrogen as the driving force. Compressive heating of the ullage gas in the receiving tank could lead to a hazardous situation if any hydrazine leaked through to the ullage side of the bladder and was heated above about 175 F, where it can undergo spontaneous exothermic decomposition. Early analysis of the flight data indicated that the ullage compression process was much closer to an isothermal than an adiabatic one. In this study, a thorough review of the pertinent literature was used to make an a priori best-estimate for the ullage gas heat transfer coefficient (defining the Nusselt Number as a function of Reynolds and Rayleigh Numbers). Experimental data from the flight were analyzed in detail. It is evident that there is considerably more heat transfer than can be accounted for by conduction alone, but the observed increases do not correlate well with Reynolds Number, Rayleigh Number or vehicle acceleration. There are large gaps in the present understanding of convective heat transfer in closed containers with internal heat generation, especially in the presence of vibrations or other random disturbances. A program of experiments to fill in these gaps is suggested, covering both ground and orbital environments.

  14. An analysis of ullage heat transfer in the orbital refueling system

    NASA Astrophysics Data System (ADS)

    Kauffman, D.

    1986-07-01

    The Orbital Refueling System was an experiment flown on Shuttle Mission STS 41-G in October, 1984. Liquid hydrazine fuel was transferred back and forth from one spherical bladder tank to another using pressurized nitrogen as the driving force. Compressive heating of the ullage gas in the receiving tank could lead to a hazardous situation if any hydrazine leaked through to the ullage side of the bladder and was heated above about 175 F, where it can undergo spontaneous exothermic decomposition. Early analysis of the flight data indicated that the ullage compression process was much closer to an isothermal than an adiabatic one. In this study, a thorough review of the pertinent literature was used to make an a priori best-estimate for the ullage gas heat transfer coefficient (defining the Nusselt Number as a function of Reynolds and Rayleigh Numbers). Experimental data from the flight were analyzed in detail. It is evident that there is considerably more heat transfer than can be accounted for by conduction alone, but the observed increases do not correlate well with Reynolds Number, Rayleigh Number or vehicle acceleration. There are large gaps in the present understanding of convective heat transfer in closed containers with internal heat generation, especially in the presence of vibrations or other random disturbances. A program of experiments to fill in these gaps is suggested, covering both ground and orbital environments.

  15. Stratigraphy, Sequence, and Crater Populations of Lunar Impact Basins from Lunar Orbiter Laser Altimeter (LOLA) Data: Implications for the Late Heavy Bombardment

    NASA Technical Reports Server (NTRS)

    Fassett, C. I.; Head, J. W.; Kadish, S. J.; Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2012-01-01

    New measurements of the topography of the Moon from the Lunar Orbiter Laser Altimeter (LOLA)[1] provide an excellent base-map for analyzing the large crater population (D.20 km)of the lunar surface [2, 3]. We have recently used this data to calculate crater size-frequency distributions (CSFD) for 30 lunar impact basins, which have implications for their stratigraphy and sequence. These data provide an avenue for assessing the timing of the transitions between distinct crater populations characteristic of ancient and young lunar terrains, which has been linked to the late heavy bombardment (LHB). We also use LOLA data to re-examine relative stratigraphic relationships between key lunar basins.

  16. Soft tissue cephalometric analysis applied to regional Indian population

    PubMed Central

    Upadhyay, Jay S.; Maheshwari, Sandhya; Verma, Sanjeev K.; Zahid, Syed Naved

    2013-01-01

    Introduction: Importance of soft tissue consideration in establishing treatment goals for orthodontics and orthognathic surgery has been recognized and various cephalometric analysis incorporating soft tissue parameters have evolved. The great variance in soft tissue drape of the human face and perception of esthetics exists and normative data based on one population group cannot be applied to all. The study was conducted to compare the standard soft tissue cephalometric analysis (STCA) norms with norms derived for population of western Uttar Pradesh region of India. Materials and Methods: The sample consisted of lateral cephalograms taken in natural head position of 33 normal subjects (16 males, 17 females). The cephalograms were analyzed with soft tissue cephalometric analysis for orthodontic diagnosis and treatment planning, and the Student's t test was used to compare the difference in means between study population and standard STCA norms. Results: Compared with established STCA norms, females in our study had steeper maxillary occlusal plane, more proclined mandibular incisors, and less protrusive lips. Both males and females showed an overall decrease in facial lengths, less prominent midface and mandibular structures and more convex profile compared with established norms for the White population. Conclusions: Statistically significant differences were found in certain key parameters of STCA for western Uttar Pradesh population when compared with established norms. PMID:24665169

  17. Molecular structure, vibrational spectroscopic, hyperpolarizability, natural bond orbital analysis, frontier molecular orbital analysis and thermodynamic properties of 2,3,4,5,6-pentafluorophenylacetic acid.

    PubMed

    Balachandran, V; Karunakaran, V

    2014-06-01

    The FT-IR (4000-400cm(-)(1)) and FT-Raman spectra (3500-100cm(-)(1)) of 2,3,4,5,6-pentafluorophenylacetic acid (PAA) have been recorded. Density functional theory calculation with LSDA/6-31+G(d,p) and B3LYP/6-31+G(d,p) basis sets have been used to determine ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities, Raman intensities and bonding features of the title compound. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of PAA are calculated using B3LYP/6-31+G(d,p) method on the finite-field approach. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The stability of molecule has been analyzed by using NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within this molecule. Mulliken population analysis on atomic charges is also calculated. Thermodynamic properties (heat capacity, enthalpy, Gibb's free energy and entropy) of the title compound at different temperatures were calculated. PMID:24662720

  18. Modified electronic population analysis for transition-metal complexes

    SciTech Connect

    Noell, J.O.

    1982-01-01

    A modification to the Mulliken electronic population analysis designed primarily for use on transition-metal systems is presented. All terms arising from the metal basis functions including diagonal terms are repartioned between the metal and the ligands. This reapportionment is an attempt to reflect more accurately the actual electron density in well-defined areas of space, which characterize the metal and the ligand. This modified analysis appears to yield more reasonable charge assignments than a conventional Mulliken analysis. The cost of the analysis is negligible in comparison with that of calculating the wave function.

  19. Chemical bonding analysis for solid-state systems using intrinsic oriented quasiatomic minimal-basis-set orbitals

    SciTech Connect

    Yao, Y. X.; Wang, C. Z.; Ho, K. M.

    2010-06-16

    A chemical bonding scheme is presented for the analysis of solid-state systems. The scheme is based on the intrinsic oriented quasiatomic minimal-basis-set orbitals (IO-QUAMBOs) previously developed by Ivanic and Ruedenberg for molecular systems. In the solid-state scheme, IO-QUAMBOs are generated by a unitary transformation of the quasiatomic orbitals located at each site of the system with the criteria of maximizing the sum of the fourth power of interatomic orbital bond order. Possible bonding and antibonding characters are indicated by the single particle matrix elements, and can be further examined by the projected density of states. We demonstrate the method by applications to graphene and (6,0) zigzag carbon nanotube. The oriented-orbital scheme automatically describes the system in terms of sp{sup 2} hybridization. The effect of curvature on the electronic structure of the zigzag carbon nanotube is also manifested in the deformation of the intrinsic oriented orbitals as well as a breaking of symmetry leading to nonzero single particle density matrix elements. In an additional study, the analysis is performed on the Al{sub 3}V compound. The main covalent bonding characters are identified in a straightforward way without resorting to the symmetry analysis. Our method provides a general way for chemical bonding analysis of ab initio electronic structure calculations with any type of basis sets.

  20. Linkage and association analysis in pedigrees from different populations.

    PubMed

    Beyene, Joseph; Yan, Jun; Greenwood, Celia M T

    2005-01-01

    Using the Genetic Analysis Workshop 14 simulated datasets we carried out nonparametric linkage analyses and applied a log-linear method for analysis of case-parent-triad data with stratification on parental mating type. We proposed and applied a random effect modelling approach to explore the impact of population heterogeneity on tests of association between genetic markers and disease status. The estimated genetic effect may appear to be strongly significant in one population but nonsignificant in another population, leading to confusion about interpretation. However, when results are interpreted in the light of a random effects model, both studies may be making similar statements about a genetic effect that varies depending on environment and background. PMID:16451671

  1. Stacks: an analysis tool set for population genomics

    PubMed Central

    CATCHEN, JULIAN; HOHENLOHE, PAUL A.; BASSHAM, SUSAN; AMORES, ANGEL; CRESKO, WILLIAM A.

    2014-01-01

    Massively parallel short-read sequencing technologies, coupled with powerful software platforms, are enabling investigators to analyse tens of thousands of genetic markers. This wealth of data is rapidly expanding and allowing biological questions to be addressed with unprecedented scope and precision. The sizes of the data sets are now posing significant data processing and analysis challenges. Here we describe an extension of the Stacks software package to efficiently use genotype-by-sequencing data for studies of populations of organisms. Stacks now produces core population genomic summary statistics and SNP-by-SNP statistical tests. These statistics can be analysed across a reference genome using a smoothed sliding window. Stacks also now provides several output formats for several commonly used downstream analysis packages. The expanded population genomics functions in Stacks will make it a useful tool to harness the newest generation of massively parallel genotyping data for ecological and evolutionary genetics. PMID:23701397

  2. Microsatellite and Wolbachia analysis in Rhagoletis cerasi natural populations: population structuring and multiple infections

    PubMed Central

    Augustinos, Antonios A; Asimakopoulou, Anastasia K; Moraiti, Cleopatra A; Mavragani-Tsipidou, Penelope; Papadopoulos, Nikolaos T; Bourtzis, Kostas

    2014-01-01

    Rhagoletis cerasi (Diptera: Tephritidae) is a major pest of sweet and sour cherries in Europe and parts of Asia. Despite its economic significance, there is a lack of studies on the genetic structure of R. cerasi populations. Elucidating the genetic structure of insects of economic importance is crucial for developing phenological-predictive models and environmental friendly control methods. All natural populations of R. cerasi have been found to harbor the endosymbiont Wolbachia pipientis, which widely affects multiple biological traits contributing to the evolution of its hosts, and has been suggested as a tool for the biological control of insect pests and disease vectors. In the current study, the analysis of 18 R. cerasi populations collected in Greece, Germany, and Russia using 13 microsatellite markers revealed structuring of R. cerasi natural populations, even at close geographic range. We also analyzed the Wolbachia infection status of these populations using 16S rRNA-, MLST- and wsp-based approaches. All 244 individuals screened were positive for Wolbachia. Our results suggest the fixation of the wCer1 strain in Greece while wCer2, wCer4, wCer5, and probably other uncharacterized strains were also detected in multiply infected individuals. The role of Wolbachia and its potential extended phenotypes needs a thorough investigation in R. cerasi. Our data suggest an involvement of this symbiont in the observed restriction in the gene flow in addition to a number of different ecological factors. PMID:24963388

  3. Introducing Dynamic Analysis Using Malthus's Principle of Population.

    ERIC Educational Resources Information Center

    Pingle, Mark

    2003-01-01

    Declares the use of dynamic models is increasing in macroeconomics. Explains how to introduce dynamic models to students whose technical skills are modest or varied. Chooses Malthus's Principle of Population as a natural context for introducing dynamic analysis because it provides a method for reviewing the mathematical tools and theoretical…

  4. Fluid-orbit coupling calculation for flight analysis of impulsively driven laser vehicle

    NASA Astrophysics Data System (ADS)

    Takahashi, Masayuki; Ohnishi, Naofumi

    2013-08-01

    Using a fluid-orbit coupling simulator, we numerically solve the three-dimensional Navier-Stokes equations with exchanging information of six-degree-of-freedom reactions for predicting impulsive flight motions of a laser propulsion vehicle driven by blast waves. By feedback of angular and translational velocities into the flowfield, pressure and viscous drags induced by the unsteady vehicle motion are introduced to provide precise motion analysis. In the impulsive-motion estimation of the laser-boosted vehicle, restoring forces and moments are underestimated if the vehicle motion effect is modeled using aerodynamic coefficients of steady flow. Also, a simple model using impulse data examined by experiments for predicting the impulsive motion is compared with our coupling approach which can reproduce instantaneous acceleration resulting from the interaction between the vehicle and the blast wave. Velocity overshoot is generated by evaluating sharp thrust through the coupling calculation, and the flight height becomes 6% larger than conventional prediction using the impulse data.

  5. TCP/IP Interface for the Satellite Orbit Analysis Program (SOAP)

    NASA Technical Reports Server (NTRS)

    Carnright, Robert; Stodden, David; Coggi, John

    2009-01-01

    The Transmission Control Protocol/ Internet protocol (TCP/IP) interface for the Satellite Orbit Analysis Program (SOAP) provides the means for the software to establish real-time interfaces with other software. Such interfaces can operate between two programs, either on the same computer or on different computers joined by a network. The SOAP TCP/IP module employs a client/server interface where SOAP is the server and other applications can be clients. Real-time interfaces between software offer a number of advantages over embedding all of the common functionality within a single program. One advantage is that they allow each program to divide the computation labor between processors or computers running the separate applications. Secondly, each program can be allowed to provide its own expertise domain with other programs able to use this expertise.

  6. Laboratory Reproduction and Failure Analysis of Cracked Orbiter Reaction Control System Niobium Thruster Injectors

    NASA Technical Reports Server (NTRS)

    Jacobs, Jeremy B.; Castner, Willard L.

    2007-01-01

    A viewgraph presentation describing cracks and failure analysis of an orbiter reaction control system is shown. The topics include: 1) Endeavour STS-113 Landing; 2) RCS Thruster; 3) Thruster Cross-Section; 4) RCS Injector; 5) RCS Thruster, S/N 120l 6) Counterbore Cracks; 7) Relief Radius Cracks; 8) RCS Thruster Cracking History; 9) Thruster Manufacturing Timelines; 10) Laboratory Reproduction of Injector Cracking; 11) The Brownfield Specimen; 12) HF EtchantTests/Specimen Loading; 13) Specimen #3 HF + 600F; 14) Specimen #3 IG Fracture; 15) Specimen #5 HF + 600F; 16) Specimen #5 Popcorn ; 17) Specimen #5 Cleaned and Bent; 18) HF Exposure Test Matrix; 19) Krytox143AC Tests; 20) KrytoxTests/Specimen Loading; 21) Specimen #13 Krytox + 600F; and 22) KrytoxExposure Test Matrix.

  7. Symmetry analysis of phosphorene: electronic structure with spin-orbit interaction

    NASA Astrophysics Data System (ADS)

    Li, Pengke; Appelbaum, Ian; Appelbaum's Group Team

    2015-03-01

    We present a symmetry analysis of electronic band structure including spin-orbit interaction close to the insulating gap edge in monolayer black phosphorus (``phosphorene''). Expressions for energy dispersion relation and spin-dependent eigenstates for electrons and holes are found via simplification of a perturbative expansion in wave vector k away from the zone center using elementary group theory. Importantly, we expose the underlying symmetries giving rise to substantial anisotropy in optical absorption, charge, and spin transport properties, and reveal the mechanism responsible for valence band distortion and possible lack of a true direct gap. We discovered that, spin flip processes are decoupled by symmetry from flexural phonons, allowing us to predict a spin lifetime comparable to bulk Si, vastly greater than graphene.

  8. Space shuttle orbiter digital data processing system timing sensitivity analysis OFT ascent phase

    NASA Technical Reports Server (NTRS)

    Lagas, J. J.; Peterka, J. J.; Becker, D. A.

    1977-01-01

    Dynamic loads were investigated to provide simulation and analysis of the space shuttle orbiter digital data processing system (DDPS). Segments of the ascent test (OFT) configuration were modeled utilizing the information management system interpretive model (IMSIM) in a computerized simulation modeling of the OFT hardware and software workload. System requirements for simulation of the OFT configuration were defined, and sensitivity analyses determined areas of potential data flow problems in DDPS operation. Based on the defined system requirements and these sensitivity analyses, a test design was developed for adapting, parameterizing, and executing IMSIM, using varying load and stress conditions for model execution. Analyses of the computer simulation runs are documented, including results, conclusions, and recommendations for DDPS improvements.

  9. Field line and Particle orbit Analysis in the Periphery of the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Matsumoto, Yutaka; Oikawa, Shun-ichi; Watanabe, Tsuguhiro

    2002-07-01

    Magnetic field lines and particle orbits were analyzed in the periphery of the Large Helical Device (LHD), which is called the chaotic field line region in this paper. The widths of the chaotic field line region were numerically identified for the standard LHD configuration with the magnetic axis position Rax = 3.75 m and for an improved confinement configuration with Rax = 3.6 m. It was found that the reflected particles include of what we have named chaotic particles and non-chaotic particles. Most of the reflected particles are mirror-confined with strong adiabaticity in the chaotic field line region. The remaining reflected particles, named type-A and type-B particles, are harmful to confinement. We found by detailed analysis of the vacuum magnetic field in the LHD that there exist loss canals that are the open intersections of |\\mbi{B}| = const. and \\mbi{B} \\cdot \

  10. Geometric simulation analysis of multi-band mosaic imaging from the same orbit by agile satellites

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Chen, Jinwei; Chen, Yueting; Xu, Zhihai; Feng, Huajun; Li, Qi

    2015-08-01

    This paper establishes a geometric model of multi-band mosaic imaging from the same orbit by agile satellites, and introduces a self-write simulation software. Geometric parameters of each band are calculated based on the attitude control ability of the satellite and the mission requirements. Considering the different ground resolution and the imaging angle of each band, two new concepts, Gradient Entropy and Structure Similarity Parameter are presented. These two values are used to evaluate the change of image quality caused by agility, and help to estimate the effect of the mission. By building the geometric model and calculating the agile information with the program, we propose a new approach of forward analysis of agile imaging, which helps users evaluate the image degradation.

  11. Analysis of the orbit errors in the CERN accelerators using model simulation

    SciTech Connect

    Lee, M.; Kleban, S.; Clearwater, S.; Scandale, W.; Pettersson, T.; Kugler, H.; Riche, A.; Chanel, M.; Martensson, E.; Lin, In-Ho

    1987-09-01

    This paper will describe the use of the PLUS program to find various types of machine and beam errors such as, quadrupole strength, dipole strength, beam position monitors (BPMs), energy profile, and beam launch. We refer to this procedure as the GOLD (Generic Orbit and Lattice Debugger) Method which is a general technique that can be applied to analysis of errors in storage rings and transport lines. One useful feature of the Method is that it analyzes segments of a machine at a time so that the application and efficiency is independent of the size of the overall machine. Because the techniques are the same for all the types of problems it solves, the user need learn only how to find one type of error in order to use the program.

  12. Orbital thermal analysis of lattice structured spacecraft using color video display techniques

    NASA Technical Reports Server (NTRS)

    Wright, R. L.; Deryder, D. D.; Palmer, M. T.

    1983-01-01

    A color video display technique is demonstrated as a tool for rapid determination of thermal problems during the preliminary design of complex space systems. A thermal analysis is presented for the lattice-structured Earth Observation Satellite (EOS) spacecraft at 32 points in a baseline non Sun-synchronous (60 deg inclination) orbit. Large temperature variations (on the order of 150 K) were observed on the majority of the members. A gradual decrease in temperature was observed as the spacecraft traversed the Earth's shadow, followed by a sudden rise in temperature (100 K) as the spacecraft exited the shadow. Heating rate and temperature histories of selected members and color graphic displays of temperatures on the spacecraft are presented.

  13. Thermal Analysis for Orbiter and ISS Plume Impingement on International Space Station

    NASA Technical Reports Server (NTRS)

    Rochelle, William C.; Reid, Ethan A.; Carl, Terry L.; Smith, Ries N.; Lumpkin, Forrest E.

    2001-01-01

    The NASA Reaction Control System (RCS) Plume Model (RPM) is an exhaust plume flow field and impingement heating code that has been updated and applied to components of the International Space Station (ISS). The objective of this study was to use this code to determine if plume environments from either Orbiter PRCS jets or ISS reboost and Attitude Control System (ACS) jets cause thermal issues on ISS component surfaces. This impingement analysis becomes increasingly important as the ISS is being assembled with its first permanent crew scheduled to arrive by the end of fall 2000. By early summer 2001 , the ISS will have a number of major components installed such as the Unity (Node 1), Destiny (Lab Module), Zarya (Functional Cargo Block), and Zvezda (Service Module) along with the P6 solar arrays and radiators and the Z-1 truss. Plume heating to these components has been analyzed with the RPM code as well as additional components for missions beyond Flight 6A such as the Propulsion Module (PM), Mobile Servicing System, Space Station Remote Manipulator System, Node 2, and the Cupola. For the past several years NASA/JSC has been developing the methodology to predict plume heating on ISS components. The RPM code is a modified source flow code with capabilities for scarfed nozzles and intersecting plumes that was developed for the 44 Orbiter RCS jets. This code has been validated by comparison with Shuttle Plume Impingement Flight Experiment (SPIFEX) heat flux and pressure data and with CFD and Method of Characteristics solutions. Previous analyses of plume heating predictions to the ISS using RPM have been reported, but did not consider thermal analysis for the components nor jet-firing histories as the Orbiter approaches the ISS docking ports. The RPM code has since been modified to analyze surface temperatures with a lumped mass approach and also uses jet-firing histories to produce pulsed heating rates. In addition, RPM was modified to include plume heating from ISS

  14. Analysis of the orbit distortion by the use of the wavelet transform

    SciTech Connect

    Matsushita, T.; Takao, M.; Aoyagi, H.; Takeuchi, M.; Tanaka, H.; Agui, A.; Yoshigoe, A.; Nakatani, T.

    2004-05-12

    We have adopted matching pursuit algorithm of discrete wavelet transform (DWT) for the analysis of the beam position shift correlated with the motion of insertion device (ID). The beam position data measured by the rf beam position monitors have included high-frequency 'noises' and fluctuation of background level. Precise evaluation of the electron beam position shift correlated with the motion of the ID is required for estimation of the steering magnet currents in order to suppress the closed orbit distortion (COD). The DWT is a powerful tool for frequency analysis and data processing. The analysis of DWT was applied to the beam position shift correlated with the phase motion of APPLE-2 type undulator (ID23) in SPring-8. The result of the analysis indicated that 'noises' are mainly composed of the components of 50 {approx} 6.25Hz and < 0.1Hz. We carried out the data processing to remove the 'noises' by the matching pursuit algorithm. Then we have succeeded in suppressing the COD within 2 {mu}m by the use of the steering magnet currents calculated from the processed data.

  15. Characterizing Oxidation State using Bader Analysis, Maximally Localized Wannier Functions and Atomic Orbitals Projection

    NASA Astrophysics Data System (ADS)

    Reeves, Kyle; Kanai, Yosuke

    2013-03-01

    The concept of oxidation state of atoms in molecules and materials is widely used to predict and understand chemical and physical properties. This concept is perhaps driven more empirically than by any rigorous criteria differentiating one oxidation state from another. Within the oxidation state framework, an integer number of electrons is assigned to the nuclei within a system. In practice, a distribution of electron density makes it difficult to quantify such discrete assignments without some ambiguities. We explore three different charge analysis approaches in density functional theory calculations for addressing the oxidation state of important organometallic molecules [Ru(bpy)3]2+ and [Ru(bpy)3]3+, which are widely used for solar energy conversion applications. Bader charge analysis, Wannier function analysis, and atomic orbital projection are employed in this work. Given the highly-localized nature of the d-electrons of the ruthenium atom, the charge analysis methods are also compared with Hubbard-U correction. We also discuss how the solvation by water molecules influences the oxidation state characterization for these organometallic complexes.

  16. Orbit-based analysis of resonant excitations of Alfvén waves in tokamaks

    SciTech Connect

    Bierwage, Andreas; Shinohara, Kouji

    2014-11-15

    The exponential growth phase of fast-ion-driven Alfvénic instabilities is simulated and the resonant wave-particle interactions are analyzed numerically. The simulations are carried out in realistic magnetic geometry and with a realistic particle distribution for a JT-60U plasma driven by negative-ion-based neutral beams. In order to deal with the large magnetic drifts of the fast ions, two new mapping methods are developed and applied. The first mapping yields the radii and pitch angles at the points, where the unperturbed orbit of a particle intersects the mid-plane. These canonical coordinates allow to express analysis results (e.g., drive profiles and resonance widths) in a form that is easy to understand and directly comparable to the radial mode structure. The second mapping yields the structure of the wave field along the particle trajectory. This allows us to unify resonance conditions for trapped and passing particles, determine which harmonics are driven, and which orders of the resonance are involved. This orbit-based resonance analysis (ORA) method is applied to fast-ion-driven instabilities with toroidal mode numbers n = 1-3. After determining the order and width of each resonance, the kinetic compression of resonant particles and the effect of linear resonance overlap are examined. On the basis of the ORA results, implications for the fully nonlinear regime, for the long-time evolution of the system in the presence of a fast ion source, and for the interpretation of experimental observations are discussed.

  17. Meta-Orbital Transition in Heavy-Fermion Systems: Analysis by Dynamical Mean Field Theory and Self-Consistent Renormalization Theory of Orbital Fluctuations

    NASA Astrophysics Data System (ADS)

    Hattori, Kazumasa

    2010-11-01

    We investigate a two-orbital Anderson lattice model with Ising orbital intersite exchange interactions on the basis of a dynamical mean field theory combined with the static mean field approximation of intersite orbital interactions. Focusing on Ce-based heavy-fermion compounds, we examine the orbital crossover between two orbital states, when the total f-electron number per site nf is ˜1. We show that a “meta-orbital” transition, at which the occupancy of two orbitals changes steeply, occurs when the hybridization between the ground-state f-electron orbital and conduction electrons is smaller than that between the excited f-electron orbital and conduction electrons at low pressures. Near the meta-orbital critical end point, orbital fluctuations are enhanced and couple with charge fluctuations. A critical theory of meta-orbital fluctuations is also developed by applying the self-consistent renormalization theory of itinerant electron magnetism to orbital fluctuations. The critical end point, first-order transition, and crossover are described within Gaussian approximations of orbital fluctuations. We discuss the relevance of our results to CeAl2, CeCu2Si2, CeCu2Ge2, and related compounds, which all have low-lying crystalline-electric-field excited states.

  18. Natural bond orbital analysis, electronic structure and vibrational spectral analysis of N-(4-hydroxyl phenyl) acetamide: A density functional theory

    NASA Astrophysics Data System (ADS)

    Govindasamy, P.; Gunasekaran, S.; Ramkumaar, G. R.

    2014-09-01

    The Fourier transform infrared (FT-IR) and FT-Raman spectra of N-(4-hydroxy phenyl) acetamide (N4HPA) of painkiller agent were recorded in the region 4000-450 cm-1 and 4000-50 cm-1 respectively. Density functional theory (DFT) has been used to calculate the optimized geometrical parameter, atomic charges, and vibrational wavenumbers and intensity of the vibrational bands. The computed vibrational wave numbers were compared with the FT-IR and FT-Raman experimental data. The computational calculations at DFT/B3LYP level with 6-31G(d,p), 6-31++G(d,p), 6-311G(d,p) and 6-311++G(d,p) basis sets. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using Vibrational energy distribution analysis (VEDA 4) program. The oscillator’s strength calculated by TD-DFT and N4HPA is approach complement with the experimental findings. The NMR chemical shifts 13C and 1H were recorded and calculated using the gauge independent atomic orbital (GIAO) method. The molecular electrostatic potential (MESP) and electron density surfaces of the molecule were constructed. The Natural charges and intermolecular contacts have been interpreted using Natural Bond orbital (NBO) analysis the HOMO-LUMO energy gap has been calculated. The thermodynamic properties like entropy, heat capacity and zero vibrational energy have been calculated.

  19. Analysis of the structural continuity in twinned crystals in terms of pseudo-eigensymmetry of crystallographic orbits.

    PubMed

    Marzouki, Mohamed Amine; Souvignier, Bernd; Nespolo, Massimo

    2014-01-01

    The reticular theory of twinning gives the necessary conditions on the lattice level for the formation of twins. The latter are based on the continuation, more or less approximate, of a substructure through the composition surface. The analysis of this structural continuity can be performed in terms of the eigensymmetry of the crystallographic orbits corresponding to occupied Wyckoff positions in the structure. If [Formula: see text] is the space group of the individual and [Formula: see text] a space group which fixes the twin lattice obtained as an intersection of the space groups of the individuals in their respective orientations, then a structural continuity is obtained if (1) the eigensymmetry of an orbit under [Formula: see text] contains the twin operation; (2) the eigensymmetry of a union of orbits under [Formula: see text] contains the twin operation; (3) the eigensymmetry of a split orbit under [Formula: see text] contains the twin operation; or (4) the eigensymmetry of a union of split orbits under [Formula: see text] contains the twin operation. The case of the twins in melilite is analysed: the (approximate) restoration of some of the orbits explains the formation of these twins. PMID:25075318

  20. Analysis of the structural continuity in twinned crystals in terms of pseudo-eigensymmetry of crystallographic orbits

    PubMed Central

    Marzouki, Mohamed Amine; Souvignier, Bernd; Nespolo, Massimo

    2014-01-01

    The reticular theory of twinning gives the necessary conditions on the lattice level for the formation of twins. The latter are based on the continuation, more or less approximate, of a substructure through the composition surface. The analysis of this structural continuity can be performed in terms of the eigensymmetry of the crystallographic orbits corresponding to occupied Wyckoff positions in the structure. If is the space group of the individual and a space group which fixes the twin lattice obtained as an intersection of the space groups of the individuals in their respective orientations, then a structural continuity is obtained if (1) the eigensymmetry of an orbit under contains the twin operation; (2) the eigensymmetry of a union of orbits under contains the twin operation; (3) the eigensymmetry of a split orbit under contains the twin operation; or (4) the eigensymmetry of a union of split orbits under contains the twin operation. The case of the twins in melilite is analysed: the (approximate) restoration of some of the orbits explains the formation of these twins. PMID:25075318

  1. Orbital Metastases from Breast Cancer: Retrospective Analysis at an Academic Cancer Center.

    PubMed

    Pierson, Tiffany M; Tebit, Emaculate V; El Sayed, Ali; Smolkin, Mark E; Dillon, Patrick M

    2016-07-01

    Orbital metastases from breast cancer (BC) are rare, but often debilitating. BC accounts for nearly half of metastases to the orbit. Orbital metastases may be discovered years after the initial diagnosis of BC, and are rare at initial presentation. A search of the institutional data base at an academic cancer center identified BC patients who developed or presented with orbital metastases from 2000 to 2013. Baseline characteristics, treatment modalities, survival and treatment responses were collected from the electronic medical record. There were 20 patients identified with orbital metastases (0.7% of all BC cases). The median age at diagnosis of BC was 49 years; 80% had estrogen positive disease. The interval between the initial diagnosis of BC and the presentation of orbital metastases was 8.5 years (0-19 years). Orbital disease was the initial presentation of BC in two cases. Three patients developed bilateral orbital metastases and seven had accompanying brain metastases. The most common presentation was decreased vision (55%), followed by diplopia (25%). The median survival after orbital metastases was 24 months. Thirteen patients (65%) received local radiation therapy. Of those radiated, 90% reported improvement of orbital symptoms. Other treatments included intraocular bevacizumab, surgery, and systemic therapy. Orbital metastases tend to occur in estrogen receptor positive disease and are often found years after BC onset. Orbital metastases may be associated with the development of brain metastases. Radiotherapy is the preferred local therapy and had high symptom control in this cohort. Oncologists should be aware of the signs of orbital metastases and the treatment options. PMID:27143519

  2. Genetic analysis in the Collaborative Cross breeding population

    SciTech Connect

    Philip, Vivek; Sokoloff, Greta; Ackert-Bicknell, Cheryl; Striz, Martin; Branstetter, Lisa R; Beckmann, Melissa; Spence, Jason S; Jackson, Barbara L; Galloway, Leslie D; Barker, Gene; Wymore, Ann M; Hunsicker, Patricia R; Durtschi, David W; Shaw, Ginger S; Shinpock, Sarah G; Manly, Kenneth F; Miller, Darla R; Donahue, Kevin; Culiat, Cymbeline T; Churchill, Gary A; Lariviere, William R; Palmer, Abraham; O'Hara, Bruce; Voy, Brynn H; Chesler, Elissa J

    2011-01-01

    Genetic reference populations in model organisms are critical resources for systems genetic analysis of disease related phenotypes. The breeding history of these inbred panels may influence detectable allelic and phenotypic diversity. The existing panel of common inbred strains reflects historical selection biases, and existing recombinant inbred panels have low allelic diversity. All such populations may be subject to consequences of inbreeding depression. The Collaborative Cross (CC) is a mouse reference population with high allelic diversity that is being constructed using a randomized breeding design that systematically outcrosses eight founder strains, followed by inbreeding to obtain new recombinant inbred strains. Five of the eight founders are common laboratory strains, and three are wild-derived. Since its inception, the partially inbred CC has been characterized for physiological, morphological, and behavioral traits. The construction of this population provided a unique opportunity to observe phenotypic variation as new allelic combinations arose through intercrossing and inbreeding to create new stable genetic combinations. Processes including inbreeding depression and its impact on allelic and phenotypic diversity were assessed. Phenotypic variation in the CC breeding population exceeds that of existing mouse genetic reference populations due to both high founder genetic diversity and novel epistatic combinations. However, some focal evidence of allele purging was detected including a suggestive QTL for litter size in a location of changing allele frequency. Despite these inescapable pressures, high diversity and precision for genetic mapping remain. These results demonstrate the potential of the CC population once completed and highlight implications for development of related populations. Supplementary material consists of Supplementary Table 1 Phenotypic means, variances, ranges and heritabilities for all traits and generations, Supplementary Table

  3. Methods for the survey and genetic analysis of populations

    DOEpatents

    Ashby, Matthew

    2003-09-02

    The present invention relates to methods for performing surveys of the genetic diversity of a population. The invention also relates to methods for performing genetic analyses of a population. The invention further relates to methods for the creation of databases comprising the survey information and the databases created by these methods. The invention also relates to methods for analyzing the information to correlate the presence of nucleic acid markers with desired parameters in a sample. These methods have application in the fields of geochemical exploration, agriculture, bioremediation, environmental analysis, clinical microbiology, forensic science and medicine.

  4. Dilution-of-Precision-Based Lunar Surface Navigation System Analysis Utilizing Lunar Orbiters

    NASA Technical Reports Server (NTRS)

    Welch, Bryan W.; Connolly, Joseph W.; Sands, Obed S.

    2007-01-01

    The NASA Vision for Space Exploration is focused on the return of astronauts to the Moon. Although navigation systems have already been proven in the Apollo missions to the Moon, the current exploration campaign will involve more extensive and extended missions requiring new concepts for lunar navigation. In contrast to Apollo missions, which were limited to the near-side equatorial region of the Moon, those under the Exploration Systems Initiative will require navigation on the Moon's limb and far side. Since these regions have poor Earth visibility, a navigation system comprised solely of Earth-based tracking stations will not provide adequate navigation solutions in these areas. In this report, a dilution-of-precision (DoP)-based analysis of the performance of a network of Moon orbiting satellites is provided. This analysis extends a previous analysis of a lunar network (LN) of navigation satellites by providing an assessment of the capability associated with a variety of assumptions. These assumptions pertain to the minimum surface user elevation angle and a total single satellite failure in the lunar network. The assessment is accomplished by making appropriately formed estimates of DoP. Different adaptations of DoP, such as geometric DoP and positional DoP (GDoP and PDoP), are associated with a different set of assumptions regarding augmentations to the navigation receiver or transceiver.

  5. Orbit-determination performance of Doppler data for interplanetary cruise trajectories. Part 1: Error analysis methodology

    NASA Technical Reports Server (NTRS)

    Ulvestad, J. S.; Thurman, S. W.

    1992-01-01

    An error covariance analysis methodology is used to investigate different weighting schemes for two-way (coherent) Doppler data in the presence of transmission-media and observing-platform calibration errors. The analysis focuses on orbit-determination performance in the interplanetary cruise phase of deep-space missions. Analytical models for the Doppler observable and for transmission-media and observing-platform calibration errors are presented, drawn primarily from previous work. Previously published analytical models were improved upon by the following: (1) considering the effects of errors in the calibration of radio signal propagation through the troposphere and ionosphere as well as station-location errors; (2) modelling the spacecraft state transition matrix using a more accurate piecewise-linear approximation to represent the evolution of the spacecraft trajectory; and (3) incorporating Doppler data weighting functions that are functions of elevation angle, which reduce the sensitivity of the estimated spacecraft trajectory to troposphere and ionosphere calibration errors. The analysis is motivated by the need to develop suitable weighting functions for two-way Doppler data acquired at 8.4 GHz (X-band) and 32 GHz (Ka-band). This weighting is likely to be different from that in the weighting functions currently in use; the current functions were constructed originally for use with 2.3 GHz (S-band) Doppler data, which are affected much more strongly by the ionosphere than are the higher frequency data.

  6. Orbital service module systems analysis study documentation. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Potentially feasible system concepts for providing additional power, thermal control, and attitude to the baseline orbiter were investigated in order to support a greater variety of space missions and to extend the orbiter's ability to remain in orbit. Results of these analyses include an incremental growth plan that offers the flexibility of adding capability as, and when, it is needed in order to satisfy emerging user requirements.

  7. Thermal and structural analysis of the GOES scan mirror's on orbit performance

    NASA Technical Reports Server (NTRS)

    Zurmehly, G. E.; Hookman, R. A.

    1991-01-01

    The on-orbit performance of the GOES satellite's scan mirror has been predicted by means of thermal, structural, and optical models. A simpler-than-conventional thermal model was used to reduce the time required to obtain orbital predictions, and the structural model was used to predict on-earth gravity sag and on-orbit distortions. The transfer of data from the thermal model to the structural model was automated for a given set of thermal nodes and structural grids.

  8. Molecular population genetic analysis of emerged bacterial pathogens: selected insights.

    PubMed Central

    Musser, J. M.

    1996-01-01

    Research in bacterial population genetics has increased in the last 10 years. Population genetic theory and tools and related strategies have been used to investigate bacterial pathogens that have contributed to recent episodes of temporal variation in disease frequency and severity. A common theme demonstrated by these analyses is that distinct bacterial clones are responsible for disease outbreaks and increases in infection frequency. Many of these clones are characterized by unique combinations of virulence genes or alleles of virulence genes. Because substantial interclonal variance exists in relative virulence, molecular population genetic studies have led to the concept that the unit of bacterial pathogenicity is the clone or cell line. Continued new insights into host parasite interactions at the molecular level will be achieved by combining clonal analysis of bacterial pathogens with large-scale comparative sequencing of virulence genes. PMID:8903193

  9. Analysis of the effect of various disturbing factors on high-precision forecasts of spacecraft orbits

    NASA Astrophysics Data System (ADS)

    Markov, Yu. G.; Mikhailov, M. V.; Perepelkin, V. V.; Pochukaev, V. N.; Rozhkov, S. N.; Semenov, A. S.

    2016-03-01

    The necessity of taking many force components disturbing spacecraft (SC) orbits into account is demonstrated for the example of forecasts of GLONASS ephemerides. The disturbances of SCs in high-earth orbits (HEO) and low-earth orbits (LEO) are systematized, and the degree of their effect on SC motion is estimated. Disturbance models are developed that provide essential increases of the accuracy of one-day forecasts of GLONASS and GPS ephemerides. Modeling results are presented that allow, depending on the required accuracy of SC orbit forecasts, the determination of the necessary list of disturbances included in the model.

  10. Physical meaning of the natural orbitals: Analysis of exactly solvable models

    SciTech Connect

    Helbig, N.; Rubio, A.

    2010-02-15

    We investigate the suitability of natural orbitals as a basis for describing many-body excitations. We analyze to which extent the natural orbitals describe both bound as well as ionized excited states and show that depending on the specifics of the excited state the ground-state natural orbitals may yield a good approximation. We show that the success of reduced density-matrix functional theory in describing molecular dissociation lies in the flexibility provided by fractional occupation numbers while the role of the natural orbitals is minor.

  11. Safety in earth orbit study. Volume 2: Analysis of hazardous payloads, docking, on-board survivability

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Detailed and supporting analyses are presented of the hazardous payloads, docking, and on-board survivability aspects connected with earth orbital operations of the space shuttle program. The hazards resulting from delivery, deployment, and retrieval of hazardous payloads, and from handling and transport of cargo between orbiter, sortie modules, and space station are identified and analyzed. The safety aspects of shuttle orbiter to modular space station docking includes docking for assembly of space station, normal resupply docking, and emergency docking. Personnel traffic patterns, escape routes, and on-board survivability are analyzed for orbiter with crew and passenger, sortie modules, and modular space station, under normal, emergency, and EVA and IVA operations.

  12. Sensitivity Analysis for Key Payloads and Orbital Parameters from the Next-Generation Moon-Gradiometer Satellite Gravity Program

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Hsu, Houtse; Zhong, Min; Yun, Meijuan

    2015-01-01

    This research principally focuses on the requirements analysis in terms of the next-generation Moon-Gradiometer satellite gravity program. Firstly, the new single and combined analytical error models applied to estimate the accuracy of the lunar gravitational field (e.g., geopotential coefficients, cumulative geoid height and cumulative gravity anomaly) influenced by the main error sources consisting of the satellite gravity gradient and satellite orbital position are created for the next-generation Moon-Gradiometer program. Secondly, the dependability of the new single and combined analytical error models is validated by the conformity of the cumulative lunar geoid height errors between the gravity gradient and orbital position. Finally, taking the current GRAIL (Gravity Recovery and Interior Laboratory) satellite gravity mission for reference, the sensitivity analysis for the next-generation Moon-Gradiometer gravity satellite system is comprehensively carried out. We propose to equip this with the new-type pivotal payloads of the lunar spacecraft comprising the electrostatic suspension gravity gradiometer and the drag-free control system and bring forward the matching measurement precision of the space-borne instruments (involving 3 × 10-12/s2 in the gravity gradient and 60 m in the orbital position) and the preferred orbital parameters (including an orbital altitude of 25 km, an observation period of 28 days and a sampling interval of 1 s) in the next-generation Moon-Gradiometer program.

  13. Myths in the Diagnosis and Management of Orbital Tumors

    PubMed Central

    Gündüz, Kaan; Yanık, Özge

    2015-01-01

    Orbital tumors constitute a group of diverse lesions with a low incidence in the population. Tumors affecting the eye and ocular adnexa may also secondarily invade the orbit. Lack of accumulation of a sufficient number of cases with a specific diagnosis at various orbital centers, the paucity of prospective randomized studies, animal model studies, tissue bank, and genetic studies led to the development of various myths regarding the diagnosis and treatment of orbital lesions in the past. These myths continue to influence the diagnosis and treatment of orbital lesions by orbital specialists. This manuscript discusses some of the more common myths through case summaries and a review of the literature. Detailed genotypic analysis and genetic classification will provide further insight into the pathogenesis of many orbital diseases in the future. This will enable targeted treatments even for diseases with the same histopathologic diagnosis. Phenotypic variability within the same disease will be addressed using targeted treatments. PMID:26692710

  14. Myths in the Diagnosis and Management of Orbital Tumors.

    PubMed

    Gündüz, Kaan; Yanık, Özge

    2015-01-01

    Orbital tumors constitute a group of diverse lesions with a low incidence in the population. Tumors affecting the eye and ocular adnexa may also secondarily invade the orbit. Lack of accumulation of a sufficient number of cases with a specific diagnosis at various orbital centers, the paucity of prospective randomized studies, animal model studies, tissue bank, and genetic studies led to the development of various myths regarding the diagnosis and treatment of orbital lesions in the past. These myths continue to influence the diagnosis and treatment of orbital lesions by orbital specialists. This manuscript discusses some of the more common myths through case summaries and a review of the literature. Detailed genotypic analysis and genetic classification will provide further insight into the pathogenesis of many orbital diseases in the future. This will enable targeted treatments even for diseases with the same histopathologic diagnosis. Phenotypic variability within the same disease will be addressed using targeted treatments. PMID:26692710

  15. Orbit Software Suite

    NASA Technical Reports Server (NTRS)

    Osgood, Cathy; Williams, Kevin; Gentry, Philip; Brownfield, Dana; Hallstrom, John; Stuit, Tim

    2012-01-01

    Orbit Software Suite is used to support a variety of NASA/DM (Dependable Multiprocessor) mission planning and analysis activities on the IPS (Intrusion Prevention System) platform. The suite of Orbit software tools (Orbit Design and Orbit Dynamics) resides on IPS/Linux workstations, and is used to perform mission design and analysis tasks corresponding to trajectory/ launch window, rendezvous, and proximity operations flight segments. A list of tools in Orbit Software Suite represents tool versions established during/after the Equipment Rehost-3 Project.

  16. A theoretical analysis of optimum consumer population and its control.

    PubMed

    Jiang, Z; Mao, Z; Wang, H

    1994-01-01

    consumption structure elasticity. This model was used in the correlation analysis of the coordinated healthy development of optimum consumer population and the economy. PMID:12288173

  17. Implementation of a Single-Stage-To-Orbit (SSTO) model for stability and control analysis

    NASA Technical Reports Server (NTRS)

    Ingalls, Stephen A.

    1995-01-01

    Three NASA centers: Marshall Space Flight Center (MSFC), Langley Research Center (LaRC), and Johnson Space Center (JSC) are currently involved in studying a family of single-stage- and two-stage-to-orbit (SSTO/TSTO) vehicles to serve as the next generation space transportation system (STS). A rocketed winged-body is the current focus. The configuration (WB001) is a vertically-launched, horizontally-landing system with circular cross-section. Preliminary aerodynamic data was generated by LaRC and is a combination of wind-tunnel data, empirical methods, and Aerodynamic Preliminary Analysis System-(APAS) generated values. JSC's efforts involve descent trajectory design, stability analysis, and flight control system synthesis. Analysis of WB001's static stability indicates instability in 'tuck' (C(sub mu) less than 0: Mach = 0.30, alpha greater than 3.25 deg; Mach = 0.60, alpha greater than 8.04), an unstable dihedral effects (C(sub l(beta)) greater than 0: Mach = 30,alpha less than 12 deg.; Mach = 0.60, alpha less than 10.00 deg.), and, most significantly, an unstable weathercock stability derivative, C(sub n(beta)), at all angles of attack and subsonic Mach numbers. Longitudinal trim solutions for Mach = 0.30 and 0.60 indicate flight path angle possibilities ranging from around 12 (M = 0.30) to slightly over 20 degrees at Mach = 0.60. Trim angles of attack increase from 6.24 at Mach 0.60 and 10,000 feet to 17.7 deg. at Mach 0.30, sea-level. Lateral trim was attempted for a design cross-wind of 25.0 knots. The current vehicle aerodynamic and geometric characteristics will only yield a lateral trim solution at impractical tip-fin deflections (approximately equal to 43 deg.) and bank angles (21 deg.). A study of the lateral control surfaces, tip-fin controllers for WB001, indicate increased surface area would help address these instabilities, particularly the deficiency in C(sub n(beta)), but obviously at the expense of increased vehicle weight. Growth factors of

  18. Applicability of meteor radiant determination methods depending on orbit type. II. Low-eccentric orbits

    NASA Astrophysics Data System (ADS)

    Svoren, J.; Neslusan, L.; Porubcan, V.

    1994-08-01

    All known parent bodies of meteor showers belong to bodies moving in high-eccentricity orbits (e => 0.5). Recently, asteroids in low-eccentricity orbits (e < 0.5) approaching the Earth's orbit, were suggested as another population of possible parent bodies of meteor streams. This paper deals with the problem of calculation of meteor radiants connected with the bodies in low-eccentricity orbits from the point of view of optimal results depending on the method applied. The paper is a continuation of our previous analysis of high-eccentricity orbits (Svoren, J., Neslusan, L., Porubcan, V.: 1993, Contrib. Astron. Obs. Skalnate Pleso 23, 23). Some additional methods resulting from mathematical modelling are presented and discussed together with Porter's, Steel-Baggaley's and Hasegawa's methods. In order to be able to compare how suitable the application of the individual radiant determination methods is, it is necessary to determine the accuracy with which they approximate real meteor orbits. To verify the accuracy with which the orbit of a meteoroid with at least one node at 1 AU fits the original orbit of the parent body, the Southworth-Hawkins D-criterion (Southworth, R.B., Hawkins, G.S.: 1963, Smithson. Contr. Astrophys. 7, 261) was applied. D <= 0.1 indicates a very good fit of orbits, 0.1 < D <= 0.2 is considered for a good fit and D > 0.2 means that the fit is rather poor and the change of orbit unrealistic. The optimal method, i.e. the one which results in the smallest D values for the population of low-eccentricity orbits, is that of adjusting the orbit by varying both the eccentricity and perihelion distance. A comparison of theoretical radiants obtained by various methods was made for typical representatives from each group of the NEA (near-Earth asteroids) objects.

  19. Orbital decay analysis, reentry predictions and risk assessment for the GOCE satellite

    NASA Astrophysics Data System (ADS)

    Pardini, Carmen; Anselmo, Luciano

    The ESA’s GOCE satellite was launched on 17 March 2009. After mapping the geopotential with unrivalled accuracy and detail for four years from an extremely low circular polar orbit, on 21 October 2013 the low thrust ion propulsion motor used to contrast the atmospheric drag was automatically shut down when the pressure in the xenon propellant tank dropped below a critical threshold. Then the satellite entered in “fine-pointing mode” (FPM), a phase of orbital altitude decay with active fine attitude control carried out by a set of magnetotorquers. According to the pre-launch specifications, the attitude control system was expected to compensate the gravity gradient and the aerodynamic torques up to an average drag force along the orbit of 20 mN. However the system proved itself much more robust than envisaged, remaining operational until reentry, with drag forces exceeding 2000 mN. The uncommon nature of the GOCE reentry campaign, sharing an uncontrolled orbital decay with a finely controlled attitude along the atmospheric drag direction, made the reentry predictions for this satellite an interesting case study, in particular because nobody was able to say a priori if and when the attitude control would have failed, leading to an unrestrained tumbling. Therefore, even though the casualty expectancy for this reentry was slightly above the internationally recognized alert threshold of 1/10,000, i.e. around 1/5000, it presented a number of challenges and opportunities from the prediction and risk evaluation points of view. As in previous cases, ISTI/CNR was in charge of reentry predictions for the Italian civil protection authorities and exchanged information with the other agencies involved in the framework of the international reentry campaign promoted by the Inter-Agency Space Debris Coordination Committee (IADC). Considering the peculiar nature of the GOCE reentry, the definition of reliable uncertainty windows was not easy, in particular taking into account

  20. Development of NASA's Accident Precursor Analysis Process Through Application on the Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Maggio, Gaspare; Groen, Frank; Hamlin, Teri; Youngblood, Robert

    2010-01-01

    Accident Precursor Analysis (APA) serves as the bridge between existing risk modeling activities, which are often based on historical or generic failure statistics, and system anomalies, which provide crucial information about the failure mechanisms that are actually operative in the system. APA docs more than simply track experience: it systematically evaluates experience, looking for under-appreciated risks that may warrant changes to design or operational practice. This paper presents the pilot application of the NASA APA process to Space Shuttle Orbiter systems. In this effort, the working sessions conducted at Johnson Space Center (JSC) piloted the APA process developed by Information Systems Laboratories (ISL) over the last two years under the auspices of NASA's Office of Safety & Mission Assurance, with the assistance of the Safety & Mission Assurance (S&MA) Shuttle & Exploration Analysis Branch. This process is built around facilitated working sessions involving diverse system experts. One important aspect of this particular APA process is its focus on understanding the physical mechanism responsible for an operational anomaly, followed by evaluation of the risk significance of the observed anomaly as well as consideration of generalizations of the underlying mechanism to other contexts. Model completeness will probably always be an issue, but this process tries to leverage operating experience to the extent possible in order to address completeness issues before a catastrophe occurs.

  1. Re-Entry Aeroheating Analysis of Tile-Repair Augers for the Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Mazaheri, Ali R.; Wood, William A.

    2007-01-01

    Computational re-entry aerothermodynamic analysis of the Space Shuttle Orbiter s tile overlay repair (TOR) sub-assembly is presented. Entry aeroheating analyses are conducted to characterize the aerothermodynamic environment of the TOR and to provide necessary inputs for future TOR thermal and structural analyses. The TOR sub-assembly consists of a thin plate and several augers and spacers that serve as the TOR fasteners. For the computational analysis, the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) is used. A 5-species non-equilibrium chemistry model with a finite rate catalytic recombination model and a radiation equilibrium wall condition are used. It is assumed that wall properties are the same as reaction cured glass (RCG) properties with a surface emissivity of epsilon = 0.89. Surface heat transfer rates for the TOR and tile repair augers (TRA) are computed at a STS-107 trajectory point corresponding to Mach 18 free stream conditions. Computational results show that the average heating bump factor (BF), which is a ratio of local heat transfer rate to a design reference point located at the damage site, for the auger head alone is about 1.9. It is also shown that the average BF for the combined auger and washer heads is about 2.0.

  2. Thermal stress analysis of space shuttle orbiter wing skin panel and thermal protection system

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jenkins, Jerald M.

    1987-01-01

    Preflight thermal stress analysis of the space shuttle orbiter wing skin panel and the thermal protection system (TPS) was performed. The heated skin panel analyzed was rectangular in shape and contained a small square cool region at its center. The wing skin immediately outside the cool region was found to be close to the state of elastic instability in the chordwise direction based on the conservative temperature distribution. The wing skin was found to be quite stable in the spanwise direction. The potential wing skin thermal instability was not severe enough to tear apart the strain isolation pad (SIP) layer. Also, the preflight thermal stress analysis was performed on the TPS tile under the most severe temperature gradient during the simulated reentry heating. The tensile thermal stress induced in the TPS tile was found to be much lower than the tensile strength of the TPS material. The thermal bending of the TPS tile was not severe enough to cause tearing of the SIP layer.

  3. A multiblock analysis for shuttle orbiter re-entry heating from Mach 24 to Mach 12

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Weilmuenster, K. J.; Alter, Stephen J.

    1993-01-01

    A multiblock, laminar heating analysis for the shuttle orbiter at three trajectory points ranging from Mach 24.3 to Mach 12.86 on re-entry is described. The analysis is performed using the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) with both a seven species chemical nonequilibrium model and an equilibrium model. A finite-catalytic-wall model appropriate for shuttle tiles at a radiative equilibrium wall temperature is applied. Computed heating levels are generally in good agreement with the flight data though a few rather large discrepancies remain unexplained. The multiblock relaxation strategy partitions the flowfield into manageable blocks requiring a fraction of the computational resources (time and memory) required by a full domain approach. In hot, the computational cost for a solution at even a single trajectory point would be prohibitively expensive at the given resolution without the multiblock approach. Converged blocks are reassembled to enable a fully coupled converged solution over the entire vehicle, starting from a nearly converged initial condition.

  4. Analysis of stability boundaries of satellite's equilibrium attitude in a circular orbit

    NASA Astrophysics Data System (ADS)

    Novikov, M. A.

    2016-03-01

    An asymmetric satellite equipped with control momentum gyroscopes (CMGs) with the center of mass of the system moving uniformly in a circular orbit was considered. The stability of a relative equilibrium attitude of the satellite was analyzed using Lyapunov's direct method. The Lyapunov function V is a positive definite integral of the total energy of the perturbed motion of the system. The asymptotic stability analysis of the stationary motion of the conservative system was based on the Barbashin-Krasovskii theorem on the nonexistence of integer trajectories of the set dot V, which was obtained using the differential equations of motion of the satellite with CMGs. By analyzing the sign definiteness of the quadratic part of V, it was found earlier by V.V. Sazonov that the stability region is described by four strict inequalities. The asymptotic stability at the stability boundary was analyzed by sequentially turning these inequalities into equalities with terms of orders higher than the second taken into account in V. The sign definiteness analysis of the inhomogeneous function V at the stability boundary involved a huge amount of computations related to the multiplication, expansion, substitution, and factorization of symbolic expressions. The computations were performed by applying a computer algebra system on a personal computer.

  5. Analysis and protection of stray light for the space camera at geosynchronous orbit

    NASA Astrophysics Data System (ADS)

    Jin, Xiaorui; Lin, Li

    2012-11-01

    Stray light is the general term for all non-normal transmission of light in the optical system. The influence of stray light is different according to optical system's structure. Large area array camera at geosynchronous orbit is facing more serious influence of stray light, especially for the small incident angle of sunlight on the system. It is in dire need of a detailed analysis of stray light of the basic shape of the optical system .In the paper, the influence on the camera used in space from stray light and the necessity to eliminate stray light are presented. The definition of the stray light coefficient and PST(point source transmittance) is briefed. In Tracepro, analysis of the impact of sunlight incident was made at different angles on the space camera, in the case of stray light factor for the quantitative evaluation. The design principle of the inside and outside hood is presented for the R-C (Ritchey Chretien) optical system. On this basis, in order to reduce stray light interference for the space camera, the primary and secondary mirror's hoods were designed. Finally, when the incidence angle of sunlight is more than 3° incidence on the space camera, the coefficient of stray light is less than 2%. It meets the engineering requirements.

  6. Space-based solar power conversion and delivery systems study. Volume 2: Engineering analysis of orbital systems

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Program plans, schedules, and costs are determined for a synchronous orbit-based power generation and relay system. Requirements for the satellite solar power station (SSPS) and the power relay satellite (PRS) are explored. Engineering analysis of large solar arrays, flight mechanics and control, transportation, assembly and maintenance, and microwave transmission are included.

  7. Continuous probabilistic analysis to evolutionary game dynamics in finite populations.

    PubMed

    Gao, Meng

    2009-07-01

    Evolutionary game dynamics of two strategies in finite population is studied by continuous probabilistic approach. Besides frequency dependent selection, mutation was also included in this study. The equilibrium probability density functions of abundance, expected time to extinction or fixation were derived and their numerical solutions are calculated as illustrations. Meanwhile, individual-based computer simulations are also done. A comparison reveals the consistency between theoretical analysis and simulations. PMID:19219510

  8. Atmospheric, Orbital and Eclipse Depth Analysis of the Hot Jupiter HAT-P-30-WASP-51b

    NASA Astrophysics Data System (ADS)

    Foster, Andrew S.; Harrington, Joseph; Cubillos, Patricio; Blecic, Jasmina; Foster, A. J.; Challener, Ryan; Garland, Justin

    2015-11-01

    HAT-P-30-WASP-51b is a hot-Jupiter planet that orbits an F star every 2.8106 days at a distance of 0.0419 AU. Using the Spitzer Space Telescope in 2012 (Spitzer Program Number 70084) we observed two secondary eclipses of the planet, one in the 3.6 μm channel on 3 January and one in the 4.5 μm channel on 17 January. We present eclipse-depth measurements of 0.00163 ± 0.0001 and 0.00146 ± 0.00013 and we esitmate the infrared brightness temperatures to be 1900 ± 50 and 1600 ± 60 for these two channels, respectively, from an analysis using our Photometry for Orbits, Eclipses, and Transits (POET) pipeline. We also refine its orbit using our own secondary-eclipse measurements in combination with radial-velocity and transit observations from both professional and amateur observers. The most notable result from this orbital analysis is a detection of eccentricity in the planet's orbit. Using only the phase of our secondary eclipses, we can constrain ecosw to a minimum of 0.0084 ± 0.0004, a 20 sigma detection of one component of the orbit's eccentricity that is independent of the effects that stellar tides have on radial velocity data. We then characterize its atmosphere's temperature- pressure profile and molecular abundances using our Bayesian Atmospheric Radiative Transfer code (BART). Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This work was supported by NASA Planetary Atmospheres grant NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G. J. Blecic holds a NASA Earth and Space Science Fellowship.

  9. Shape of the orbital opening: individual characterization and analysis of variability in modern humans, Gorilla gorilla, and Pan troglodytes.

    PubMed

    Schmittbuhl, M; Le Minor, J M; Allenbach, B; Schaaf, A

    1999-05-01

    The description of the human orbital shape is principally qualitative in the classical literature, and characterised by adjectives such as circular, rectangular or quadrangular. In order to provide a precise quantification and interpretation of this shape, a study based on automatic image analysis and Fourier analysis was carried out on 45 human skulls (30 males, 15 females), and for comparison on 61 skulls of Gorilla gorilla (40 males, 21 females), and 34 skulls of Pan troglodytes (20 males, 14 females). Sexual dimorphism in the shape of the orbital opening was not demonstrated. Its dominant morphological features could be characterized by Fourier analysis; elliptical elongation and quadrangularity were dominant morphological features of the shape of the orbital opening in the three species. Elliptical elongation was more marked in humans and Pan, whereas quadrangularity was particularly emphasized in Gorilla. An intraspecific variability of the shape of the orbital opening existed in humans, Gorilla and Pan, and seemed close in the three species. Interspecific partition between humans, Gorilla and Pan was demonstrated despite the variability observed in the three species studied. Interspecific differences between Gorilla and the Pan-humans group were principally explained by the differences in quadrangularity, and by differences in orientation of triangularity and pentagonality. Differences in the shape of the orbital opening between humans and Pan were principally explained by differences in hexagonality, and by differences in orientation of quadrangularity. A closeness of shape between some humans and some individuals in Pan and, to a lesser degree, with some individuals in Gorilla was observed, demonstrating the existence of a morphological continuum of the shape of the orbital opening in hominoids. PMID:10363113

  10. Choice of high-apogee AES orbits on the basis of the qualitative methods of the theory of perturbations and situational analysis. Part I. Situational studies based on orbital tori

    NASA Astrophysics Data System (ADS)

    Prokhorenko, V. I.

    2016-03-01

    The paper discusses the problems of the choice of high-apogee orbits of artificial Earth satellites (AES), proceeding from the tasks of space experiments aimed at studying near-earth space and taking into account the features of the orbital evolution and ballistic lifetime. The suggested methods of the choice of orbits consist of two components. The first is based on the use of mathematical models of studied regions of near-earth space and various techniques of situation analysis, among which the annual and daily orbital tori developed by the author about 35 years ago are key. The second component is based on qualitative methods of the theory of perturbations of high-apogee AES orbits developed by M.L. Lidov more than 50 years ago.

  11. Population.

    ERIC Educational Resources Information Center

    King, Pat; Landahl, John

    This pamphlet has been prepared in response to a new problem, a rapidly increasing population, and a new need, population education. It is designed to help teachers provide their students with some basic population concepts with stress placed on the elements of decision making. In the first section of the pamphlet, some of the basic concepts of…

  12. Power Extension Package (PEP) system definition extension, orbital service module systems analysis study. Volume 2: PEP

    NASA Technical Reports Server (NTRS)

    1979-01-01

    User power, duration, and orbit requirements, which were the prime factors influencing power extension package (PEP) design, are discussed. A representative configuration of the PEP concept is presented and the major elements of the system are described as well as the PEP-to-Orbiter and remote manipulator interface provisions.

  13. Shuttle cryogenics supply system. Optimization study. Volume 5 B-4: Programmers manual for space shuttle orbit injection analysis (SOPSA)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A computer program for space shuttle orbit injection propulsion system analysis (SOPSA) is described to show the operational characteristics and the computer system requirements. The program was developed as an analytical tool to aid in the preliminary design of propellant feed systems for the space shuttle orbiter main engines. The primary purpose of the program is to evaluate the propellant tank ullage pressure requirements imposed by the need to accelerate propellants rapidly during the engine start sequence. The SOPSA program will generate parametric feed system pressure histories and weight data for a range of nominal feedline sizes.

  14. Morphological and morphometrical analysis of Heterodera spp. populations in Jordan

    PubMed Central

    Lafi, Hamzeh A.; Al-Banna, Luma; Sadder, Monther T.; Migdadi, Hussein M.

    2015-01-01

    Phenotypic diversity of five Jordanian populations of cyst nematodes, Heterodera spp. collected from five regions from Jordan (Ar-Ramtha, Madaba, Dana, Al-Karak, and Jerash) was investigated. Soil samples were collected from one representative field in each region. Morphological and morphometrical characteristics revealed that Heterodera latipons is dominated in cereal fields at Ar-Ramtha, Madaba, Dana and Al-Karak regions and Heterodera schachtii in Jerash. Cysts populations from all cereal fields had bifenestrate vulval cone and a strong underbridge. Wherever, cysts of the cabbage population had ambifenestrate vulval cone with long vulval slit. The bullae were absent in Ar-Ramtha, Madaba and Dana populations, but present in Al-Karak and Jerash. Based on 12 morphometrical characters, the first three functions in canonical discriminant analysis accounted 99.3% of the total variation. Distance from dorsal gland duct opening to stylet base, underbridge length, a = L/W (body length/midbody width) and length of hyaline tail tip had strong and significant contributions in the first function. While the second function was strongly influenced by length of hyaline tail, fenestral length, fenestral width and tail length. However, the third canonical discriminate function was found to be influenced by stylet length, fenestral length, a = L/W (body length/midbody width) and underbridge width. The graphical representation of the distribution of the samples showed that the first canonical discriminant function clearly separated H. schachtii from Jerash from other populations. Whereas, H. latipons collected from Madaba and Dana were clearly separated in the second function. The results indicated that differences at morphological and morphometrical levels revealed diverse populations of Heterodera spp. in Jordan. PMID:26858546

  15. Morphological and morphometrical analysis of Heterodera spp. populations in Jordan.

    PubMed

    Lafi, Hamzeh A; Al-Banna, Luma; Sadder, Monther T; Migdadi, Hussein M

    2016-01-01

    Phenotypic diversity of five Jordanian populations of cyst nematodes, Heterodera spp. collected from five regions from Jordan (Ar-Ramtha, Madaba, Dana, Al-Karak, and Jerash) was investigated. Soil samples were collected from one representative field in each region. Morphological and morphometrical characteristics revealed that Heterodera latipons is dominated in cereal fields at Ar-Ramtha, Madaba, Dana and Al-Karak regions and Heterodera schachtii in Jerash. Cysts populations from all cereal fields had bifenestrate vulval cone and a strong underbridge. Wherever, cysts of the cabbage population had ambifenestrate vulval cone with long vulval slit. The bullae were absent in Ar-Ramtha, Madaba and Dana populations, but present in Al-Karak and Jerash. Based on 12 morphometrical characters, the first three functions in canonical discriminant analysis accounted 99.3% of the total variation. Distance from dorsal gland duct opening to stylet base, underbridge length, a = L/W (body length/midbody width) and length of hyaline tail tip had strong and significant contributions in the first function. While the second function was strongly influenced by length of hyaline tail, fenestral length, fenestral width and tail length. However, the third canonical discriminate function was found to be influenced by stylet length, fenestral length, a = L/W (body length/midbody width) and underbridge width. The graphical representation of the distribution of the samples showed that the first canonical discriminant function clearly separated H. schachtii from Jerash from other populations. Whereas, H. latipons collected from Madaba and Dana were clearly separated in the second function. The results indicated that differences at morphological and morphometrical levels revealed diverse populations of Heterodera spp. in Jordan. PMID:26858546

  16. Perturbation theory analysis of competition in a heterogeneous population

    NASA Astrophysics Data System (ADS)

    Utzny, C.; Burroughs, N. J.

    2003-01-01

    A physiologically structured population model of T cell populations at the end of an immune response is proposed and analysed. The proposed model describes a T cell population with a structured death rate mediated by cytokine receptor surface expression. This provides a structuring that determines the ability of a T cell to compete for survival cytokines. Homogeneous differentiation into memory combined with heterogeneous survival abilities leads to a system of nonlinear first-order integro differential equations. The mathematical model is studied analytically by a perturbation approach which agrees well with numerical integrations. We find that the structured death rate leads to selection of T cells expressing high cytokine receptor levels. Selection in this model is independent of the initial T cell distribution which allows us to define a universal selection curve, a property lost under receptor downregulation (i.e. loss of cytokine receptors from the surface). Furthermore, we examine the effects of a population dependent memory differentiation rate and of cytokine receptor downregulation on selection. A population dependent memory differentiation rate increases selection significantly while putting an upper bound on the number of T cells differentiating into memory. Under receptor downregulation a dramatic change of the memory T cell distribution is induced. We find that there exists a critical ratio of the receptor downregulation rate to the average T cell death rate for which selection becomes maximal. Our analysis reveals that this maximum property is the result of an interplay between single cell dynamics and population dynamics. We propose that the selection studied in this paper plays an important role in the selection of optimal T cells for the memory pool.

  17. Population genetic analysis of Enterocytozoon bieneusi in humans.

    PubMed

    Li, Wei; Cama, Vitaliano; Feng, Yaoyu; Gilman, Robert H; Bern, Caryn; Zhang, Xichen; Xiao, Lihua

    2012-01-01

    Genotyping based on sequence analysis of the ribosomal internal transcribed spacer has revealed significant genetic diversity in Enterocytozoonbieneusi. Thus far, the population genetics of E. bieneusi and its significance in the epidemiology of microsporidiosis have not been examined. In this study, a multilocus sequence typing of E. bieneusi in AIDS patients in Lima, Peru was conducted, using 72 specimens previously genotyped as A, D, IV, EbpC, WL11, Peru7, Peru8, Peru10 and Peru11 at the internal transcribed spacer locus. Altogether, 39 multilocus genotypes were identified among the 72 specimens. The observation of strong intragenic linkage disequilibria and limited genetic recombination among markers were indicative of an overall clonal population structure of E. bieneusi. Measures of pair-wise intergenic linkage disequilibria and a standardised index of association (IAS) based on allelic profile data further supported this conclusion. Both sequence-based and allelic profile-based phylogenetic analyses showed the presence of two genetically isolated groups in the study population, one (group 1) containing isolates of the anthroponotic internal transcribed spacer genotype A, and the other (group 2) containing isolates of multiple internal transcribed spacer genotypes (mainly genotypes D and IV) with zoonotic potential. The measurement of linkage disequilibria and recombination indicated group 2 had a clonal population structure, whereas group 1 had an epidemic population structure. The formation of the two sub-populations was confirmed by STRUCTURE and Wright's fixation index (FST) analyses. The data highlight the power of MLST in understanding the epidemiology of E. bieneusi. PMID:22534008

  18. On-Orbit Solar Dynamics Observatory (SDO) Star Tracker Warm Pixel Analysis

    NASA Technical Reports Server (NTRS)

    Felikson, Denis; Ekinci, Matthew; Hashmall, Joseph A.; Vess, Melissa

    2011-01-01

    This paper describes the process of identification and analysis of warm pixels in two autonomous star trackers on the Solar Dynamics Observatory (SDO) mission. A brief description of the mission orbit and attitude regimes is discussed and pertinent star tracker hardware specifications are given. Warm pixels are defined and the Quality Index parameter is introduced, which can be explained qualitatively as a manifestation of a possible warm pixel event. A description of the algorithm used to identify warm pixel candidates is given. Finally, analysis of dumps of on-orbit star tracker charge coupled devices (CCD) images is presented and an operational plan going forward is discussed. SDO, launched on February 11, 2010, is operated from the NASA Goddard Space Flight Center (GSFC). SDO is in a geosynchronous orbit with a 28.5 inclination. The nominal mission attitude points the spacecraft X-axis at the Sun, with the spacecraft Z-axis roughly aligned with the Solar North Pole. The spacecraft Y-axis completes the triad. In attitude, SDO moves approximately 0.04 per hour, mostly about the spacecraft Z-axis. The SDO star trackers, manufactured by Galileo Avionica, project the images of stars in their 16.4deg x 16.4deg fields-of-view onto CCD detectors consisting of 512 x 512 pixels. The trackers autonomously identify the star patterns and provide an attitude estimate. Each unit is able to track up to 9 stars. Additionally, each tracker calculates a parameter called the Quality Index, which is a measure of the quality of the attitude solution. Each pixel in the CCD measures the intensity of light and a warns pixel is defined as having a measurement consistently and significantly higher than the mean background intensity level. A warns pixel should also have lower intensity than a pixel containing a star image and will not move across the field of view as the attitude changes (as would a dim star image). It should be noted that the maximum error introduced in the star tracker

  19. Climate change threatens polar bear populations: a stochastic demographic analysis.

    PubMed

    Hunter, Christine M; Caswell, Hal; Runge, Michael C; Regehr, Eric V; Amstrup, Steve C; Stirling, Ian

    2010-10-01

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambdas, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambdas approximately - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population

  20. Climate change threatens polar bear populations: A stochastic demographic analysis

    USGS Publications Warehouse

    Hunter, C.M.; Caswell, H.; Runge, M.C.; Regehr, E.V.; Amstrup, Steven C.; Stirling, I.

    2010-01-01

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in ?? in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log ??s, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log ??s ' - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic

  1. Conformational stability, spectroscopic and computational studies, hikes' occupied molecular orbital, lowest unoccupied molecular orbital, natural bond orbital analysis and thermodynamic parameters of anticancer drug on nanotube-A review.

    PubMed

    Ghasemi, A S; Mashhadban, F; Hoseini-Alfatemi, S M; Sharifi-Rad, J

    2015-01-01

    Today the use of nanotubes (CNTs) is widely spread a versatile vector for drug delivery that can officiate as a platform for transporting a variety of bioactive molecules, such as drugs. In the present study, the interaction between the nanotube and anticancer drugs is investigated. Density functional theory (DFT) calculations were using the Gauss view and the complexes were optimized by B3LYP method using B3LYP/6-31G (d, p) and B3LYP/6-311++G (d, p) basis set in the gas phase and water solution at 298.15K. The calculated hikes' occupied molecular orbital (HOMO) and the lowest unoccupied (LUMO) energies Show that charge transfer occurs within the molecule. Furthermore, the effects of interactions on the natural bond orbital analysis (NBO) have been used to a deeper investigation into the studied compounds. These factors compete against each other to determine the adsorption behavior of the tube computer simulation is seen to be capable to optimize anticancer drug design. This review article mainly concentrates on the different protocols of loading anticancer drugs onto CNTs as well as how to control the anticancer drug release and cancer treatment. PMID:26718433

  2. A Detailed Analysis of Stellar Populations in Galaxies During Reionization

    NASA Astrophysics Data System (ADS)

    Finkelstein, Steven

    2010-09-01

    We request archival funds to complete a robust study of galaxies in the z > 7 Universe using a new set of unprecedentedly deep data from HST WFC3/IR. These data probe an epoch when the Universe was only 500 - 800 Myr old, placing constraints on the earliest phases of galaxy formation. We recently completed a thorough study of the HUDF with WFC3. Using robust analysis techniques to study the stellar populations in these galaxies, we improved upon early release papers to provide a valuable analysis to the community. We will continue this work, combining the HUDF, HUDF-01 and HUDF-02 datasets to compile a sample ~ 3X larger. We will search for galaxies at z = 7 - 9 within this dataset by computing photometric redshifts, which offers a smaller redshift uncertainty than typical Lyman break color-criteria selection, as well as allowing a more complete census of the galaxy population at z > 7. We will run bootstrap Monte Carlo simulations on our sample, which place strong constraints on the presence of primordial stellar populations in these galaxies - this is more physically accurate than other studies, which have only reported the standard error on the mean, which does not give information on how well one can rule out certain scenarios. Lastly, we will fit the full spectral energy distributions of these objects to a suite of stellar population models, computing confidence ranges on each property. As we found in our previous work, although the age and dust are difficult to constrain, the stellar mass is well constrained with only rest-UV detections due to the old age of the Universe. A 3X increase in sample size nearly doubles the accuracy with which we can pin down the stellar populations in these galaxies.At such high redshifts, large samples of galaxies are expensive and extremely hard to come by. The opportunity to examine a sample of ~ 100 z > 7 galaxies is a unique one, and by applying our robust techniques, we will present the most complete analysis of the galaxy

  3. The Orbital Evolution of 2007 VA85, an Amor-type Asteroid on a Retrograde Orbit.

    NASA Astrophysics Data System (ADS)

    Kankiewicz, P.; Włodarczyk, I.

    2010-06-01

    Among the known population of asteroids on retrograde orbits (i > 90°) we found an object classified as an Amor-type asteroid. During the analysis of the first results of astrometry, we found some possible Earth-impact solutions for this asteroid. After taking into account the latest observations, we excluded any significant impact solution. However, this asteroid is the first known example of potentially hazardous object on a retrograde orbit. We also investigated the orbital evolution of 2007 VA85 (1 My in the past), obtaining possible scenarios of its dynamical origin.

  4. [Analysis of mitochondrial DNA haplotypes in yakut population].

    PubMed

    Fedorova, S A; Bermisheva, M A; Villems, R; Maksimova, N R; Khusnutdinova, E K

    2003-01-01

    To study the mitochondrial gene pool structure in Yakuts, polymorphism of mtDNA hypervariable segment I (16,024-16,390) was analyzed in 191 people sampled from the indigenous population of the Sakha Republic. In total, 67 haplotypes of 14 haplogroups were detected. Most (91.6%) haplotypes belonged to haplogroups A, B, C, D, F, G, M*, and Y, which are specific for East Eurasian ethnic groups; 8.4% haplotypes represented Caucasian haplogroups H, HV1, J, T, U, and W. A high frequency of mtDNA types belonging to Asian supercluster M was peculiar for Yakuts: mtDNA types belonging to haplogroup C, D, or G and undifferentiated mtDNA types of haplogroup M (M*) accounted for 81% of all haplotypes. The highest diversity was observed for haplogroups C and D, which comprised respectively 22 (44%) and 18 (30%) haplotypes. Yakuts showed the lowest genetic diversity (H = 0.964) among all Turkic ethnic groups. Phylogenetic analysis testified to a common genetic substrate of Yakuts, Mongols, and Central Asian (Kazakh, Kyrgyz, Uigur) populations. Yakuts proved to share 21 (55.5%) mtDNA haplogroups with the Central Asian ethnic groups and Mongols. Comparisons with modern paleo-Asian populations (Chukcha, Itelmen, Koryaks) revealed three (8.9%) haplotypes common for Yakuts and Koryaks. The results of mtDNA analysis disagree with the hypothesis of an appreciable paleo-Asian contribution to the modern Yakut gene pool. PMID:12942638

  5. Genetic analysis of Indian tasar silkmoth (Antheraea mylitta) populations.

    PubMed

    Chakraborty, Saikat; Muthulakshmi, M; Vardhini, Deena; Jayaprakash, P; Nagaraju, J; Arunkumar, K P

    2015-01-01

    Indian tasar silkmoth, Antheraea mylitta is an economically important wild silkmoth species distributed across India. A number of morphologically and ethologically well-defined ecotypes are known for this species that differ in their primary food plant specificity. Most of these ecotypes do not interbreed in nature, but are able to produce offspring under captive conditions. Microsatellite markers were developed for A. mylitta, and out of these, ten well-behaved microsatellite loci were used to analyze the population structure of different ecoraces. A total of 154 individual moths belonging to eight different ecoraces, were screened at each locus. Hierarchical analysis of population structure using Analysis of MOlecular VAriance (AMOVA) revealed significant structuring (FST = 0.154) and considerable inbreeding (FIS = 0.505). A significant isolation by distance was also observed. The number of possible population clusters was investigated using distance method, Bayesian algorithm and self organization maps (SOM). The first two methods revealed two distinct clusters, whereas the SOM showed the different ecoraces not to be clearly differentiated. These results suggest that although there is a large degree of phenotypic variation among the different ecoraces of A. mylitta, genetically they are not very different, and the phenotypic differences may largely be a result of their respective ecology. PMID:26510465

  6. Genetic analysis of Indian tasar silkmoth (Antheraea mylitta) populations

    PubMed Central

    Chakraborty, Saikat; Muthulakshmi, M; Vardhini, Deena; Jayaprakash, P; Nagaraju, J; Arunkumar, K. P.

    2015-01-01

    Indian tasar silkmoth, Antheraea mylitta is an economically important wild silkmoth species distributed across India. A number of morphologically and ethologically well-defined ecotypes are known for this species that differ in their primary food plant specificity. Most of these ecotypes do not interbreed in nature, but are able to produce offspring under captive conditions. Microsatellite markers were developed for A. mylitta, and out of these, ten well-behaved microsatellite loci were used to analyze the population structure of different ecoraces. A total of 154 individual moths belonging to eight different ecoraces, were screened at each locus. Hierarchical analysis of population structure using Analysis of MOlecular VAriance (AMOVA) revealed significant structuring (FST = 0.154) and considerable inbreeding (FIS = 0.505). A significant isolation by distance was also observed. The number of possible population clusters was investigated using distance method, Bayesian algorithm and self organization maps (SOM). The first two methods revealed two distinct clusters, whereas the SOM showed the different ecoraces not to be clearly differentiated. These results suggest that although there is a large degree of phenotypic variation among the different ecoraces of A. mylitta, genetically they are not very different, and the phenotypic differences may largely be a result of their respective ecology. PMID:26510465

  7. A Multidisciplinary Performance Analysis of a Lifting-Body Single-Stage-to-Orbit Vehicle

    NASA Technical Reports Server (NTRS)

    Tartabini, Paul V.; Lepsch, Roger A.; Korte, J. J.; Wurster, Kathryn E.

    2000-01-01

    Lockheed Martin Skunk Works (LMSW) is currently developing a single-stage-to-orbit reusable launch vehicle called VentureStar(TM) A team at NASA Langley Research Center participated with LMSW in the screening and evaluation of a number of early VentureStar(TM) configurations. The performance analyses that supported these initial studies were conducted to assess the effect of a lifting body shape, linear aerospike engine and metallic thermal protection system (TPS) on the weight and performance of the vehicle. These performance studies were performed in a multidisciplinary fashion that indirectly linked the trajectory optimization with weight estimation and aerothermal analysis tools. This approach was necessary to develop optimized ascent and entry trajectories that met all vehicle design constraints. Significant improvements in ascent performance were achieved when the vehicle flew a lifting trajectory and varied the engine mixture ratio during flight. Also, a considerable reduction in empty weight was possible by adjusting the total oxidizer-to-fuel and liftoff thrust-to-weight ratios. However, the optimal ascent flight profile had to be altered to ensure that the vehicle could be trimmed in pitch using only the flow diverting capability of the aerospike engine. Likewise, the optimal entry trajectory had to be tailored to meet TPS heating rate and transition constraints while satisfying a crossrange requirement.

  8. OBSERVATIONS AND ORBITAL ANALYSIS OF THE GIANT WHITE DWARF BINARY SYSTEM HR 5692

    SciTech Connect

    Stefanik, Robert P.; Torres, Guillermo; Latham, David W.; Landsman, Wayne; Craig, Nathaniel; Murrett, James

    2011-05-15

    We report spectroscopic observations of the red giant star HR 5692, previously known to be a binary system both from other spectroscopic work and from deviations in the astrometric motion detected by the Hipparcos satellite. Earlier International Ultraviolet Explorer (IUE) observations had shown the presence of a hot white dwarf companion to the giant primary. We have combined our radial velocity observations with other existing measurements and with the Hipparcos intermediate astrometric data to determine a complete astrometric-spectroscopic orbital solution, providing the inclination angle for the first time. We also determine an improved parallax for the system of 10.12 {+-} 0.67 mas. We derive the physical properties of the primary, and with an estimate of its mass from stellar evolution models (1.84 {+-} 0.40 M{sub sun}), we infer the mass of the white dwarf companion to be M{sub WD} = 0.59 {+-} 0.12 M{sub sun}. An analysis of an IUE white dwarf spectrum, using our parallax, yields T{sub eff} = 30, 400 {+-} 780 K, log g = 8.25 {+-} 0.15, and a mass M{sub WD} = 0.79 {+-} 0.09 M{sub sun}, in marginal agreement with the dynamical mass.

  9. Empirical predictive models of daily relativistic electron flux at geostationary orbit: Multiple regression analysis

    NASA Astrophysics Data System (ADS)

    Simms, Laura E.; Engebretson, Mark J.; Pilipenko, Viacheslav; Reeves, Geoffrey D.; Clilverd, Mark

    2016-04-01

    The daily maximum relativistic electron flux at geostationary orbit can be predicted well with a set of daily averaged predictor variables including previous day's flux, seed electron flux, solar wind velocity and number density, AE index, IMF Bz, Dst, and ULF and VLF wave power. As predictor variables are intercorrelated, we used multiple regression analyses to determine which are the most predictive of flux when other variables are controlled. Empirical models produced from regressions of flux on measured predictors from 1 day previous were reasonably effective at predicting novel observations. Adding previous flux to the parameter set improves the prediction of the peak of the increases but delays its anticipation of an event. Previous day's solar wind number density and velocity, AE index, and ULF wave activity are the most significant explanatory variables; however, the AE index, measuring substorm processes, shows a negative correlation with flux when other parameters are controlled. This may be due to the triggering of electromagnetic ion cyclotron waves by substorms that cause electron precipitation. VLF waves show lower, but significant, influence. The combined effect of ULF and VLF waves shows a synergistic interaction, where each increases the influence of the other on flux enhancement. Correlations between observations and predictions for this 1 day lag model ranged from 0.71 to 0.89 (average: 0.78). A path analysis of correlations between predictors suggests that solar wind and IMF parameters affect flux through intermediate processes such as ring current (Dst), AE, and wave activity.

  10. Charge-displacement analysis via natural orbitals for chemical valence: Charge transfer effects in coordination chemistry

    NASA Astrophysics Data System (ADS)

    Bistoni, Giovanni; Rampino, Sergio; Tarantelli, Francesco; Belpassi, Leonardo

    2015-02-01

    We recently devised a simple scheme for analyzing on quantitative grounds the Dewar-Chatt-Duncanson donation and back-donation in symmetric coordination complexes. Our approach is based on a symmetry decomposition of the so called Charge-Displacement (CD) function quantifying the charge flow, upon formation of a metal (M)-substrate (S) bond, along the M-S interaction axis and provides clear-cut measures of donation and back-donation charges in correlation with experimental observables [G. Bistoni et al., Angew. Chem., Int. Ed. 52, 11599 (2013)]. The symmetry constraints exclude of course from the analysis most systems of interest in coordination chemistry. In this paper, we show how to entirely overcome this limitation by taking advantage of the properties of the natural orbitals for chemical valence [M. Mitoraj and A. Michalak, J. Mol. Model. 13, 347 (2007)]. A general scheme for disentangling donation and back-donation in the CD function of both symmetric and non-symmetric systems is presented and illustrated through applications to M-ethyne (M = Au, Ni and W) coordination bonds, including an explicative study on substrate activation in a model reaction mechanism.

  11. Gravity field error analysis: Applications of GPS receivers and gradiometers on low orbiting platforms

    NASA Technical Reports Server (NTRS)

    Schrama, E.

    1990-01-01

    The concept of a Global Positioning System (GPS) receiver as a tracking facility and a gradiometer as a separate instrument on a low orbiting platform offers a unique tool to map the Earth's gravitational field with unprecedented accuracies. The former technique allows determination of the spacecraft's ephemeris at any epoch to within 3 to 10 cm, the latter permits the measurement of the tensor of second order derivatives of the gravity field to within 0.01 to 0.0001 Eotvos units depending on the type of gradiometer. First, a variety of error sources in gradiometry where emphasis is placed on the rotational problem pursuing as well a static as a dynamic approach is described. Next, an analytical technique is described and applied for an error analysis of gravity field parameters from gradiometer and GPS observation types. Results are discussed for various configurations proposed on Topex/Poseidon, Gravity Probe-B, and Aristoteles, indicating that GPS only solutions may be computed up to degree and order 35, 55, and 85 respectively, whereas a combined GPS/gradiometer experiment on Aristoteles may result in an acceptable solution up to degree and order 240.

  12. Photonic orbital angular momentum in starlight. Further analysis of the 2011 Starfire Optical Range Observations

    NASA Astrophysics Data System (ADS)

    Oesch, Denis W.; Sanchez, Darryl J.

    2014-07-01

    Context. Each attempt by the Atmospheric Simulation and Adaptive-optics Laboratory Testbed (ASALT) research group to detect turbulence-induced photonic orbital angular momentum (POAM) has been successful, spanning laboratory, simulation and field experiments, with the possible exception of the 2011 Starfire Optical Range (SOR) astronomical observations, a search for POAM induced by astronomical sources. Aims: The purposes of this work are to discuss how POAM from astronomical turbulent assemblages of molecules or atoms (TAMA) would appear in observations and then to reanalyze the data from the 2011 SOR observations using a more refined technique as a demonstration of POAM in starlight. Methods: This work uses the method of projections used previously in analysis of terrestrial data. Results: Using the method of projections, the noise floor of the system was reevaluated and is found to be no greater than 1%. Reevaluation of the 2011 SOR observations reveals that a POAM signal is evident in all of the data. Conclusions: POAM signals have been found in every instance of extended propagation through turbulence conducted by the ASALT research group, including the 2011 SOR observations. POAM is an inevitable result of the propagation of optical waves through turbulence. We express our gratitude to the Air Force Office of Scientific Research for their support of this research.

  13. Critical analysis of fragment-orbital DFT schemes for the calculation of electronic coupling values

    NASA Astrophysics Data System (ADS)

    Schober, Christoph; Reuter, Karsten; Oberhofer, Harald

    2016-02-01

    We present a critical analysis of the popular fragment-orbital density-functional theory (FO-DFT) scheme for the calculation of electronic coupling values. We discuss the characteristics of different possible formulations or "flavors" of the scheme which differ by the number of electrons in the calculation of the fragments and the construction of the Hamiltonian. In addition to two previously described variants based on neutral fragments, we present a third version taking a different route to the approximate diabatic state by explicitly considering charged fragments. In applying these FO-DFT flavors to the two molecular test sets HAB7 (electron transfer) and HAB11 (hole transfer), we find that our new scheme gives improved electronic couplings for HAB7 (-6.2% decrease in mean relative signed error) and greatly improved electronic couplings for HAB11 (-15.3% decrease in mean relative signed error). A systematic investigation of the influence of exact exchange on the electronic coupling values shows that the use of hybrid functionals in FO-DFT calculations improves the electronic couplings, giving values close to or even better than more sophisticated constrained DFT calculations. Comparing the accuracy and computational cost of each variant, we devise simple rules to choose the best possible flavor depending on the task. For accuracy, our new scheme with charged-fragment calculations performs best, while numerically more efficient at reasonable accuracy is the variant with neutral fragments.

  14. Gravity field error analysis - Applications of Global Positioning System receivers and gradiometers on low orbiting platforms

    NASA Technical Reports Server (NTRS)

    Schrama, Ernst J. O.

    1991-01-01

    The concept of a Global Positioning System (GPS) receiver as a tracking facility and a gradiometer as a separate instrument on a low-orbiting platform offers a unique tool to map the earth's gravitational field with unprecedented accuracies. The former technique allows determination of the spacecraft's ephemeris at any epoch to within 3-10 cm, the latter permits the measurement of the tensor of second order derivatives of the gravity field to within 0.01 to 0.0001 Eotvos units depending on the type of gradiometer. First, a variety of error sources in gradiometry where emphasis is placed on the rotational problem pursuing as well a static as a dynamic approach is described. Next, an analytical technique is described and applied for an error analysis of gravity field parameters from gradiometer and GPS observation types. Results are discussed for various configurations proposed on Topex/Poseidon, Gravity Probe-B, and Aristoteles, indicating that GPS only solutions may be computed up to degree and order 35, 55, and 85, respectively, whereas a combined GPS/gradiometer experiment on Aristoteles may result in an acceptable solution up to degree and order 240.

  15. Water Phase Change Heat Exchanger System Level Analysis for Low Lunar Orbit

    NASA Technical Reports Server (NTRS)

    Navarro, Moses; Ungar, Eugene; Sheth, Rubik; Hansen, Scott

    2016-01-01

    In low Lunar orbit (LLO) the thermal environment is cyclic - extremely cold in the eclipse and as warm as room temperature near the subsolar point. Phase change material heat exchangers (PCHXs) are the best option for long term missions in these environments. The Orion spacecraft will use a n-pentadecane wax PCHX for its envisioned mission to LLO. Using water as a PCM material is attractive because its higher heat of fusion and greater density result in a lighter, more compact PCHX. To assess the use of a water PCHX for a human spacecraft in a circular LLO, a system level analysis was performed for the Orion spacecraft. Three cases were evaluated: 1) A one-to-one replacement of the wax PCHX on the internal thermal control loop with a water PCHX (including the appropriate control modifications), 2) reducing the radiator return setpoint temperature below Orion's value to enhance PCHX freezing, and 3) placing the water PCM on the external loop. The model showed that the water PCHX could not be used as a drop-in replacement for the wax PCHX. It did not freeze fully during the eclipse owing to its low freezing point. To obtain equivalent performance, 40% more radiator area than the Orion baseline was required. The study shows that, although water PCHXs are attractive at a component level, system level effects mean that they are not the best choice for LLO.

  16. Parametric analysis of performance and design characteristics for advanced earth-to-orbit shuttles

    NASA Technical Reports Server (NTRS)

    Willis, E. A., Jr.; Strack, W. C.; Padrutt, J. A.

    1972-01-01

    Performance, trajectory, and design characteristics are presented for (1) a single-stage shuttle with a single advanced rocket engine, (2) a single-stage shuttle with an initial parallel chemical engine and advanced engine burn followed by an advanced engine sustainer burn, (3) a single-stage shuttle with an initial chemical engine burn followed by an advanced engine burn, and (4) a two-stage shuttle with a chemical propulsion booster stage and an advanced propulsion upper stage. The ascent trajectory profile includes a brief initial vertical rise; zero-lift flight through the sensible atmosphere; variational steering into an 83-kilometer by 185-kilometer intermediate orbit; and a fixed, 460-meter per second allowance for subsequent maneuvers. Results are given in terms of burnout mass fractions (including structure and payload), trajectory profiles, propellant loadings, and burn times. These results are generated with a trajectory analysis that includes a parametric variation of the specific impulse from 800 to 3000 seconds and the specific engine weight from 0 to 1.0.

  17. An analysis of return flux from the Space Shuttle Orbiter RCS engines

    NASA Technical Reports Server (NTRS)

    Ehlers, H. K. F.

    1984-01-01

    The return flux from the Space Shuttle Orbiter reaction control system (RCS) engines to sensors in the open payload bay has been analyzed on the basis of Shuttle/Payload Contamination Evaluation (SPACE II) model predictions and orbital flight measurements. Model data are presented showing the variations of molecular return flux values with Orbiter orientation and instrument direction. The effects of multiple molecular collisions within RCS engine plumes and in their vicinity are discussed. These collisions significantly influence the amount of plume molecules returning to payload instruments and, therefore, the amount of contaminants received.

  18. Population pharmacokinetic analysis of meloxicam in rheumatoid arthritis patients

    PubMed Central

    Meineke, Ingolf; Türck, Dietrich

    2003-01-01

    Aim To perform a nonlinear mixed effect modelling (NONMEM) population pharmacokinetic analysis of meloxicam plasma concentrations in rheumatoid arthritis (RA) patients participating in three clinical trials, and to evaluate the effects of age, weight, gender and concomitant medications on meloxicam pharmacokinetics. Methods Meloxicam was administered to RA patients once daily for 3 weeks or 6 months at doses between 7.5 and 60 mg. Plasma samples were obtained at least 7 days after the first dose and meloxicam plasma concentrations were quantified by h.p.l.c.. Results NONMEM analysis was conducted on plasma samples derived from 586 patients. A one-compartmental model was found to describe the data adequately. For a typical subject in the population, a clearance of 0.377 l h−1 (95% confidence interval (CI) 0.0304–0.449) in males and 0.347 l h−1 (95% CI 0.274-0.419) in females was obtained. The volume of distribution was estimated to be 14.9 l. The findings were corroborated by subsequent analysis using WinBUGS. Analysis of covariates showed that age and gender both significantly (P < 0.005) affected clearance. The effect of age was relatively small and a dose adjustment of <10% was deemed unnecessary. Differences between males and females were attributed to differences in weight. No clinically relevant drug-drug interactions were found, although sulphasalazine and glucocorticoids both significantly (P < 0.005) affected meloxicam clearance (+19% and −12%, respectively). The mechanisms by which these agents affect meloxicam clearance remain to be elucidated. Conclusions The population pharmacokinetic meloxicam data from patients with RA gave similar results to those obtained from phase I trials. However, uncommon drug interactions may not be detected in phase I trials because of the small number of observations made. PMID:12534638

  19. JSC Orbital Debris Website Description

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2006-01-01

    required. These data also help in the analysis and interpretation of impact features on returned spacecraft surfaces. 4) Mitigation - Controlling the growth of the orbital debris population is a high priority for NASA, the United States, and the major space-faring nations of the world to preserve near-Earth space for future generations. Mitigation measures can take the form of curtailing or preventing the creation of new debris, designing satellites to withstand impacts by small debris, and implementing operational procedures ranging from utilizing orbital regimes with less debris, adopting specific spacecraft attitudes, and even maneuvering to avoid collisions with debris. Downloadable items include several documents in PDF format and executable software.and 5) Reentry - Because of the increasing number of objects in space, NASA has adopted guidelines and assessment procedures to reduce the number of non-operational spacecraft and spent rocket upper stages orbiting the Earth. One method of postmission disposal is to allow reentry of these spacecraft, either from orbital decay (uncontrolled entry) or with a controlled entry. Orbital decay may be achieved by firing engines to lower the perigee altitude so that atmospheric drag will eventually cause the spacecraft to enter. However, the surviving debris impact footprint cannot be guaranteed to avoid inhabited landmasses. Controlled entry normally occurs by using a larger amount of propellant with a larger propulsion system to drive the spacecraft to enter the atmosphere at a steeper flight path angle. It will then enter at a more precise latitude, longitude, and footprint in a nearly uninhabited impact region, generally located in the ocean.

  20. Robust Extraction and Multi-Technique Analysis of Micrometeoroids Captured in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Westphal, A. J.; Graham, G. A.; Bench, G.; Brennan, S.; Luening, K.; Pianetta, P.; Keller, L. P.; Flynn, G. J.; Snead, C.; Dominquez, G.

    2003-01-01

    The use of low-density silica aerogel as the primary capture cell technology for the NASA Discovery mission Stardust to Comet Wild-2 [1] is a strong motivation for researchers within the Meteoritics community to develop techniques to handle this material. The unique properties of silica aerogel allow dust particles to be captured at hypervelocity speeds and to remain partially intact. The same unique properties present difficulties in the preparation of particles for analysis. Using tools borrowed from microbiologists, we have developed techniques for robustly extracting captured hypervelocity dust particles and their residues from aerogel collectors[2-3]. It is important not only to refine these extraction techniques but also to develop protocols for analyzing the captured particles. Since Stardust does not return material to Earth until 2006, researchers must either analyze particles that are impacted in the laboratory using light-gasgun facilities [e.g. 41 or examine aerogel collectors that have been exposed in low-Earth orbit (LEO) [5]. While there are certainly benefits in laboratory shots, i.e. accelerating known compositions of projectiles into aerogel, the LEO capture particles offer the opportunity to investigate real particles captured under real conditions. The aerogel collectors used in this research are part of the NASA Orbital Debris Collection Experiment that was exposed on the MIR Space Station for 18 months [5]. We have developed the capability at the UCB Space Sciences Laboratory to extract tiny volumes of aerogel that completely contain each impact event, and to mount them on micromachined fixtures so that they can be analyzed with no interfering support (Fig.1). These aerogel keystones simultaneously bring the terminal particle and the particle track to within 10 m (15 g cm- ) of the nearest aerogel surface. The extracted aerogel wedges containing both the impact tracks and the captured particles have been characterized using the synchrotron

  1. DPTRAJ/ODP - DOUBLE PRECISION TRAJECTORY ANALYSIS AND ORBIT DETERMINATION PROGRAM

    NASA Technical Reports Server (NTRS)

    Breckheimer, P. J.

    1994-01-01

    The Double Precision Trajectory Analysis Program, DPTRAJ, and the Orbit Determination Program, ODP, have been developed and improved over the years to provide the NASA Jet Propulsion Laboratory with a highly reliable and accurate navigation capability for their deep space missions such as VOYAGER. DPTRAJ and ODP are each collections of programs which work together to provide the desired computational results. DPTRAJ, ODP, and their supporting utility programs are capable of handling the massive amounts of data and performing the various numerical calculations required for solving the navigation problems associated with planetary fly-by and lander missions. They were used extensively in support of NASA's VOYAGER project. DPTRAJ produces a spacecraft ephemeris by numerical integration of the equations of motion, which can be formulated using a full set of acceleration models. For each particular trajectory case the extent of the modeling employed and the precision of the integration process are controlled by user input specifications. The equation of motion used includes four types of terms. An acceleration term accounts for the basic conic motion of the spacecraft with respect to the central body. Terms that measure the attraction of the perturbing bodies on the spacecraft and terms that indirectly affect the motion as perturbations on the central body may be included. Terms are also provided to account for other gravitational and non-gravitational effects on the motion. ODP's function is the processing of the observational data in order to compute precise estimates of the spacecraft, or lander, position coordinate histories. This function is executed by processing the observation data and auxiliary calibration information. ODP also computes a spacecraft state vector, or a lander position vector, along with parameters which define the acceleration. The heart of the ODP process is a data fitting subprocess in which validated, edited, and corrected observational data

  2. A Comprehensive Analysis in Terms of Molecule-Intrinsic Quasi-Atomic Orbitals. IV. Bond Breaking and Bond Forming along the Dissociative Reaction Path of Dioxetane.

    PubMed

    West, Aaron C; Schmidt, Michael W; Gordon, Mark S; Ruedenberg, Klaus

    2015-10-15

    The quantitative analysis of molecular density matrices in terms of oriented quasi-atomic orbitals (QUAOs) is shown to yield detailed conceptual insight into the dissociation of dioxetane on the basis of ab initio wave functions. The QUAOs persist and can be followed throughout the reaction path. The kinetic bond orders and the orbital populations of the QUAOs quantitatively reveal the changes of the bonding interactions along the reaction path. At the transition state the OO bond is broken, and the molecule becomes a biradical. After the transition state the reaction path bifurcates. The minimum energy path gently descends from the transition state via a valley-ridge inflection point to a second saddle point, from which two new minimum energy paths lead to two equivalent formaldehyde dimers. The CC bond breaks, and the π-bonds of the formaldehyde fragments form in close vicinity of the second saddle point. The changes of the interactions in this region are elucidated by the analysis of the rearrangements of the QUAOs. PMID:26371996

  3. A Collaborative Analysis Tool for Thermal Protection Systems for Single Stage to Orbit Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Alexander, Reginald A.; Stanley, Thomas Troy

    1999-01-01

    Presented is a design tool and process that connects several disciplines which are needed in the complex and integrated design of high performance reusable single stage to orbit (SSTO) vehicles. Every system is linked to every other system and in the case of SSTO vehicles with air breathing propulsion, which is currently being studied by the National Aeronautics and Space Administration (NASA); the thermal protection system (TPS) is linked directly to almost every major system. The propulsion system pushes the vehicle to velocities on the order of 15 times the speed of sound in the atmosphere before pulling up to go to orbit which results high temperatures on the external surfaces of the vehicle. Thermal protection systems to maintain the structural integrity of the vehicle must be able to mitigate the heat transfer to the structure and be lightweight. Herein lies the interdependency, in that as the vehicle's speed increases, the TPS requirements are increased. And as TPS masses increase the effect on the propulsion system and all other systems is compounded. To adequately determine insulation masses for a vehicle such as the one described above, the aeroheating loads must be calculated and the TPS thicknesses must be calculated for the entire vehicle. To accomplish this an ascent or reentry trajectory is obtained using the computer code Program to Optimize Simulated Trajectories (POST). The trajectory is then used to calculate the convective heat rates on several locations on the vehicles using the Miniature Version of the JA70 Aerodynamic Heating Computer Program (MINIVER). Once the heat rates are defined for each body point on the vehicle, then insulation thicknesses that are required to maintain the vehicle within structural limits are calculated using Systems Improved Numerical Differencing Analyzer (SINDA) models. If the TPS masses are too heavy for the performance of the vehicle the process may be repeated altering the trajectory or some other input to

  4. Vector correlation analysis for inelastic and reactive collisions between partners possessing spin and orbital angular momentum.

    PubMed

    Balint-Kurti, Gabriel G; Vasyutinskii, Oleg S

    2009-12-31

    A general reactive collision of the type A + B --> C + D is considered where both the collision partners (A and B) or the products (C and D) may possess internal, i.e., spin, orbital or rotational, angular momenta. Compact expressions are derived using a rigorous quantum mechanical analysis for the angular momentum anisotropy of either of the products (C or D) arising from an initially polarized distribution of the reactant angular momentum. The angular momentum distribution of the product is expressed in terms of canonical spherical tensors multiplied by anisotropy-transforming coefficients c(K(i)q(k))(K)(K(r),L). These coefficients act as transformation coefficients between the angular momentum anisotropy of the reactants and that of the product. They are independent of scattering angle but depend on the details of the scattering dynamics. The relationship between the coefficients c(K(i)q(k))(K)(K(r),L) and the body-fixed scattering S matrix is given and the methodology for the quantum mechanical calculation of the anisotropy-transforming coefficients is clearly laid out. The anisotropy-transforming coefficients are amenable to direct experimental measurement in a similar manner to vector correlation and alignment parameters in photodissociation processes. A key aspect of the theory is the use of projections of both reactant and product angular momenta onto the product recoil vector direction. An important new conservation rule is revealed through the analysis, namely that if the state multipole for reactant angular momentum distribution has a projection q(k) onto the product recoil vector the state multipoles for the product angular momentum distribution all have this same projection. Expressions are also presented for the distribution of the product angular momentum when its components are evaluated relative to the space-fixed Z-axis. Notes with detailed derivations of all the formulas are available as Supporting Information. PMID:19642631

  5. Small-Body Extensions for the Satellite Orbit Analysis Program (SOAP)

    NASA Technical Reports Server (NTRS)

    Carnright, Robert; Stodden, David; Coggi, John

    2008-01-01

    An extension to the SOAP software allows users to work with tri-axial ellipsoid-based representations of planetary bodies, primarily for working with small, natural satellites, asteroids, and comets. SOAP is a widely used tool for the visualization and analysis of space missions. The small body extension provides the same visualization and analysis constructs for use with small bodies. These constructs allow the user to characterize satellite path and instrument cover information for small bodies in both 3D display and numerical output formats. Tri-axial ellipsoids are geometric shapes the diameters of which are different in each of three principal x, y, and z dimensions. This construct provides a better approximation than using spheres or oblate spheroids (ellipsoids comprising two common equatorial diameters as a distinct polar diameter). However, the tri-axial ellipsoid is considerably more difficult to work with from a modeling perspective. In addition, the SOAP small-body extensions allow the user to actually employ a plate model for highly irregular surfaces. Both tri-axial ellipsoids and plate models can be assigned to coordinate frames, thus allowing for the modeling of arbitrary changes to body orientation. A variety of features have been extended to support tri-axial ellipsoids, including the computation and display of the spacecraft sub-orbital point, ground trace, instrument footprints, and swathes. Displays of 3D instrument volumes can be shown interacting with the ellipsoids. Longitude/latitude grids, contour plots, and texture maps can be displayed on the ellipsoids using a variety of projections. The distance along an arbitrary line of sight can be computed between the spacecraft and the ellipsoid, and the coordinates of that intersection can be plotted as a function of time. The small-body extension supports the same visual and analytical constructs that are supported for spheres and oblate spheroids in SOAP making the implementation of the more

  6. Mission Analysis Program for Solar Electric Propulsion (MAPSEP). Volume 1: Analytical manual for earth orbital MAPSEP

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An introduction to the MAPSEP organization and a detailed analytical description of all models and algorithms are given. These include trajectory and error covariance propagation methods, orbit determination processes, thrust modeling, and trajectory correction (guidance) schemes. Earth orbital MAPSEP contains the capability of analyzing almost any currently projected low thrust mission from low earth orbit to super synchronous altitudes. Furthermore, MAPSEP is sufficiently flexible to incorporate extended dynamic models, alternate mission strategies, and almost any other system requirement imposed by the user. As in the interplanetary version, earth orbital MAPSEP represents a trade-off between precision modeling and computational speed consistent with defining necessary system requirements. It can be used in feasibility studies as well as in flight operational support. Pertinent operational constraints are available both implicitly and explicitly. However, the reader should be warned that because of program complexity, MAPSEP is only as good as the user and will quickly succumb to faulty user inputs.

  7. A preliminary analysis of the orbit of the Mars Trojan asteroid (5261) Eureka

    NASA Astrophysics Data System (ADS)

    Mikkola, S.; Innanen, K.; Muinonen, K.; Bowell, E.

    1994-01-01

    Observations and results of orbit determination of the first known Mars Trojan asteroid (5261) Eureka are presented. We have numerically calculated the evolution of the orbital elements, and have analyzed the behavior of the motion during the next 2 Myr. Strong perturbations by planets other than Mars seem to stabilize the eccentricity of the asteroid by stirring the high order resonances present in the elliptic restricted problem. As a result, the orbit appears stable at least on megayear timescales. The difference of the mean longitudes of Mars and Eureka and the semimajor axis of the asteroid form a pair of variables that essentially behave in an adiabatic manner, while the evolution of the other orbital elements is largely determined by the pertubations due to other planets.

  8. Independent Orbiter Assessment (IOA): Analysis of the electrical power distribution and control/electrical power generation subsystem

    NASA Technical Reports Server (NTRS)

    Patton, Jeff A.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C)/Electrical Power Generation (EPG) hardware. The EPD and C/EPG hardware is required for performing critical functions of cryogenic reactant storage, electrical power generation and product water distribution in the Orbiter. Specifically, the EPD and C/EPG hardware consists of the following components: Power Section Assembly (PSA); Reactant Control Subsystem (RCS); Thermal Control Subsystem (TCS); Water Removal Subsystem (WRS); and Power Reactant Storage and Distribution System (PRSDS). The IOA analysis process utilized available EPD and C/EPG hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  9. An analysis of the orbital Evolution of a solar sail around Mercury

    NASA Astrophysics Data System (ADS)

    Vilhena de Moraes, Rodolpho; Prado, Antonio; Carvalho, Jean Paulo; Treasaco, Eva

    2016-07-01

    Solar sails are a new concept of spacecraft propulsion that uses solar radiation pressure to generate acceleration: this way the sail experiences a small but unlimited and continuous acceleration. This work presents a method for finding initial conditions for frozen orbits for a solar sail around Mercury Frozen orbits are those whose orbital elements remain constant on average. Thus, at a given latitude, the satellite always passes at the same altitude. The orbital dynamics of the solar sail is governed by the potential attraction of the main body and the Sun. Besides the J2, J3 and C22 of Mercury gravity field, the dynamical model also includes the eccentricity and inclination of the orbit of the third body (Sun) and the solar acceleration pressure. In order to remove short-period terms of the dynamical system, a double averaging technique is applied to the disturbig potential. This algorithm is a two-fold process which firstly averages over the period of the satellite and secondly averages with respect to the period of the third body. The double-averaged potential is introduced in the Lagrange Planetary equations. Thus, frozen orbits are characterized by a surface depending on three variables: the orbital semi-major axis, eccentricity and inclination. These surfaces determine orbits ranging in altitude from 300 to 1000 km, which include the altitude values considered in future scientific missions around Mercury such as BepiColombo. Finally, this work delves into the influence on the dynamics of the spacecraft for different values of the sail area-to-mass ratio, which is a parameter related to the efficiency of the solar sail Sponsored by CNPq - Brazil. The author is grateful to CNPq- Brazil for contract 306953/2014-5.

  10. Multipole error analysis using local 3-bump orbit data in Fermilab Recycler

    SciTech Connect

    Yang, M.J.; Xiao, M.; /Fermilab

    2005-05-01

    The magnetic harmonic errors of the Fermilab Recycler ring were examined using circulating beam data taken with closed local orbit bumps. Data was first parsed into harmonic orbits of first, second, and third order. Each of which was analyzed for sources of magnetic errors of corresponding order. This study was made possible only with the incredible resolution of a new BPM system that was commissioned after June of 2003.

  11. Population pharmacokinetic analysis of sorafenib in patients with solid tumours

    PubMed Central

    Jain, Lokesh; Woo, Sukyung; Gardner, Erin R; Dahut, William L; Kohn, Elise C; Kummar, Shivaani; Mould, Diane R; Giaccone, Giuseppe; Yarchoan, Robert; Venitz, Jürgen; Figg, William D

    2011-01-01

    AIMS To characterize the pharmacokinetics (PK) of sorafenib in patients with solid tumours and to evaluate the possible effects of demographic, clinical and pharmacogenetic (CYP3A4*1B, CYP3A5*3C, UGT1A9*3 and UGT1A9*5) covariates on the disposition of sorafenib. METHODS PK were assessed in 111 patients enrolled in five phase I and II clinical trials, where sorafenib 200 or 400 mg was administered twice daily as a single agent or in combination therapy. All patients were genotyped for polymorphisms in metabolic enzymes for sorafenib. Population PK analysis was performed by using nonlinear mixed effects modelling (NONMEM). The final model was validated using visual predictive checks and nonparametric bootstrap analysis. RESULTS A one compartment model with four transit absorption compartments and enterohepatic circulation (EHC) adequately described sorafenib disposition. Baseline bodyweight was a statistically significant covariate for distributional volume, accounting for 4% of inter-individual variability (IIV). PK model parameter estimates (range) for an 80 kg patient were clearance 8.13 l h−1 (3.6–22.3 l h−1), volume 213 l (50–1000 l), mean absorption transit time 1.98 h (0.5–13 h), fraction undergoing EHC 50% and average time to gall bladder emptying 6.13 h. CONCLUSIONS Overall, population PK analysis was consistent with known biopharmaceutical/PK characteristics of oral sorafenib. No clinically important PK covariates were identified. PMID:21392074

  12. Numerical analysis of orbital motion around a contact binary asteroid system

    NASA Astrophysics Data System (ADS)

    Feng, Jinglang; Noomen, Ron; Visser, Pieter; Yuan, Jianping

    2016-08-01

    The general orbital motion around a contact binary asteroid system is investigated in this study. System 1996 HW1 is explored in detail, as it is the mostly bifurcated asteroid known to date. The location of its equilibrium points (EPs) is obtained and their linear stability is studied. Families of Lyapunov, Halo and vertical periodic orbits (POs) in the vicinity of these EPs as well as their stability are found and examined, respectively. The influence of the relative size of each lobe and the shape of the ellipsoidal lobe and the rotation rate of the asteroid on the location and stability of the EPs are studied. Additionally, two families of equatorial orbits are obtained at a wide range of distances: from far away to nearby. Their stability is examined against the distance to the asteroid and the rotation rate of the asteroid, to uncover the influence of highly non-spherical gravitational field and the rotation of the asteroid on the orbital motion. Finally, resonant orbits in N commensurability with the rotation of the asteroid are found and their stability is discussed. The fast rotation of the asteroid has a stabilizing effect on the equatorial orbital motion.

  13. Demographic analysis from summaries of an age-structured population

    USGS Publications Warehouse

    Link, W.A.; Royle, J. Andrew; Hatfield, J.S.

    2003-01-01

    Demographic analyses of age-structured populations typically rely on life history data for individuals, or when individual animals are not identified, on information about the numbers of individuals in each age class through time. While it is usually difficult to determine the age class of a randomly encountered individual, it is often the case that the individual can be readily and reliably assigned to one of a set of age classes. For example, it is often possible to distinguish first-year from older birds. In such cases, the population age structure can be regarded as a latent variable governed by a process prior, and the data as summaries of this latent structure. In this article, we consider the problem of uncovering the latent structure and estimating process parameters from summaries of age class information. We present a demographic analysis for the critically endangered migratory population of whooping cranes (Grus americana), based only on counts of first-year birds and of older birds. We estimate age and year-specific survival rates. We address the controversial issue of whether management action on the breeding grounds has influenced recruitment, relating recruitment rates to the number of seventh-year and older birds, and examining the pattern of variation through time in this rate.

  14. Demixed principal component analysis of neural population data

    PubMed Central

    Kobak, Dmitry; Brendel, Wieland; Constantinidis, Christos; Feierstein, Claudia E; Kepecs, Adam; Mainen, Zachary F; Qi, Xue-Lian; Romo, Ranulfo; Uchida, Naoshige; Machens, Christian K

    2016-01-01

    Neurons in higher cortical areas, such as the prefrontal cortex, are often tuned to a variety of sensory and motor variables, and are therefore said to display mixed selectivity. This complexity of single neuron responses can obscure what information these areas represent and how it is represented. Here we demonstrate the advantages of a new dimensionality reduction technique, demixed principal component analysis (dPCA), that decomposes population activity into a few components. In addition to systematically capturing the majority of the variance of the data, dPCA also exposes the dependence of the neural representation on task parameters such as stimuli, decisions, or rewards. To illustrate our method we reanalyze population data from four datasets comprising different species, different cortical areas and different experimental tasks. In each case, dPCA provides a concise way of visualizing the data that summarizes the task-dependent features of the population response in a single figure. DOI: http://dx.doi.org/10.7554/eLife.10989.001 PMID:27067378

  15. Using Bayesian Population Viability Analysis to Define Relevant Conservation Objectives

    PubMed Central

    Green, Adam W.; Bailey, Larissa L.

    2015-01-01

    Adaptive management provides a useful framework for managing natural resources in the face of uncertainty. An important component of adaptive management is identifying clear, measurable conservation objectives that reflect the desired outcomes of stakeholders. A common objective is to have a sustainable population, or metapopulation, but it can be difficult to quantify a threshold above which such a population is likely to persist. We performed a Bayesian metapopulation viability analysis (BMPVA) using a dynamic occupancy model to quantify the characteristics of two wood frog (Lithobates sylvatica) metapopulations resulting in sustainable populations, and we demonstrate how the results could be used to define meaningful objectives that serve as the basis of adaptive management. We explored scenarios involving metapopulations with different numbers of patches (pools) using estimates of breeding occurrence and successful metamorphosis from two study areas to estimate the probability of quasi-extinction and calculate the proportion of vernal pools producing metamorphs. Our results suggest that ≥50 pools are required to ensure long-term persistence with approximately 16% of pools producing metamorphs in stable metapopulations. We demonstrate one way to incorporate the BMPVA results into a utility function that balances the trade-offs between ecological and financial objectives, which can be used in an adaptive management framework to make optimal, transparent decisions. Our approach provides a framework for using a standard method (i.e., PVA) and available information to inform a formal decision process to determine optimal and timely management policies. PMID:26658734

  16. Predictive accuracy of population viability analysis in conservation biology.

    PubMed

    Brook, B W; O'Grady, J J; Chapman, A P; Burgman, M A; Akçakaya, H R; Frankham, R

    2000-03-23

    Population viability analysis (PVA) is widely applied in conservation biology to predict extinction risks for threatened species and to compare alternative options for their management. It can also be used as a basis for listing species as endangered under World Conservation Union criteria. However, there is considerable scepticism regarding the predictive accuracy of PVA, mainly because of a lack of validation in real systems. Here we conducted a retrospective test of PVA based on 21 long-term ecological studies--the first comprehensive and replicated evaluation of the predictive powers of PVA. Parameters were estimated from the first half of each data set and the second half was used to evaluate the performance of the model. Contrary to recent criticisms, we found that PVA predictions were surprisingly accurate. The risk of population decline closely matched observed outcomes, there was no significant bias, and population size projections did not differ significantly from reality. Furthermore, the predictions of the five PVA software packages were highly concordant. We conclude that PVA is a valid and sufficiently accurate tool for categorizing and managing endangered species. PMID:10746724

  17. Using Bayesian Population Viability Analysis to Define Relevant Conservation Objectives.

    PubMed

    Green, Adam W; Bailey, Larissa L

    2015-01-01

    Adaptive management provides a useful framework for managing natural resources in the face of uncertainty. An important component of adaptive management is identifying clear, measurable conservation objectives that reflect the desired outcomes of stakeholders. A common objective is to have a sustainable population, or metapopulation, but it can be difficult to quantify a threshold above which such a population is likely to persist. We performed a Bayesian metapopulation viability analysis (BMPVA) using a dynamic occupancy model to quantify the characteristics of two wood frog (Lithobates sylvatica) metapopulations resulting in sustainable populations, and we demonstrate how the results could be used to define meaningful objectives that serve as the basis of adaptive management. We explored scenarios involving metapopulations with different numbers of patches (pools) using estimates of breeding occurrence and successful metamorphosis from two study areas to estimate the probability of quasi-extinction and calculate the proportion of vernal pools producing metamorphs. Our results suggest that ≥50 pools are required to ensure long-term persistence with approximately 16% of pools producing metamorphs in stable metapopulations. We demonstrate one way to incorporate the BMPVA results into a utility function that balances the trade-offs between ecological and financial objectives, which can be used in an adaptive management framework to make optimal, transparent decisions. Our approach provides a framework for using a standard method (i.e., PVA) and available information to inform a formal decision process to determine optimal and timely management policies. PMID:26658734

  18. Seawifs Technical Report Series. Volume 2: Analysis of Orbit Selection for Seawifs: Ascending Versus Descending Node

    NASA Technical Reports Server (NTRS)

    Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Gregg, Watson W.

    1992-01-01

    Due to range safety considerations, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color instrument may be required to be launched into a near-noon descending node, as opposed to the ascending node used by the predecessor sensor, the Coastal Zone Color Scanner (CZCS). The relative importance of ascending versus descending near-noon orbits was assessed here to determine if descending node will meet the scientific requirements of SeaWiFS. Analyses focused on ground coverage, local times of coverage, solar and viewing geometries (zenith and azimuth angles), and sun glint. Differences were found in the areas covered by individual orbits, but were not important when taken over a 16 day repeat time. Local time of coverage was also different: for ascending node orbits the Northern Hemisphere was observed in the morning and the Southern Hemisphere in the afternoon, while for descending node orbits the Northern Hemisphere was observed in the afternoon and the Southern in the morning. There were substantial differences in solar azimuth and spacecraft azimuth angles both at equinox and at the Northern Hemisphere summer solstice. Negligible differences in solar and spacecraft zenith angles, relative azimuth angles, and sun glint were obtained at the equinox. However, large differences were found in solar zenith angles, relative azimuths, and sun glint for the solstice. These differences appeared to compensate across the scan, however, an increase in sun glint in descending node over that in ascending node on the western part of the scan was compensated by a decrease on the eastern part of the scan. Thus, no advantage or disadvantage could be conferred upon either ascending node or descending node for noon orbits. Analyses were also performed for ascending and descending node orbits that deviated from a noon equator crossing time. For ascending node, afternoon orbits produced the lowest mean solar zenith angles in the Northern Hemisphere, and morning orbits produced

  19. Analysis of the volumetric relationship among human ocular, orbital and fronto-occipital cortical morphology.

    PubMed

    Masters, Michael; Bruner, Emiliano; Queer, Sarah; Traynor, Sarah; Senjem, Jess

    2015-10-01

    Recent research on the visual system has focused on investigating the relationship among eye (ocular), orbital, and visual cortical anatomy in humans. This issue is relevant in evolutionary and medical fields. In terms of evolution, only in modern humans and Neandertals are the orbits positioned beneath the frontal lobes, with consequent structural constraints. In terms of medicine, such constraints can be associated with minor deformation of the eye, vision defects, and patterns of integration among these features, and in association with the frontal lobes, are important to consider in reconstructive surgery. Further study is therefore necessary to establish how these variables are related, and to what extent ocular size is associated with orbital and cerebral cortical volumes. Relationships among these anatomical components were investigated using magnetic resonance images from a large sample of 83 individuals, which also included each subject's body height, age, sex, and uncorrected visual acuity score. Occipital and frontal gyri volumes were calculated using two different cortical parcellation tools in order to provide a better understanding of how the eye and orbit vary in relation to visual cortical gyri, and frontal cortical gyri which are not directly related to visual processing. Results indicated that ocular and orbital volumes were weakly correlated, and that eye volume explains only a small proportion of the variance in orbital volume. Ocular and orbital volumes were also found to be equally and, in most cases, more highly correlated with five frontal lobe gyri than with occipital lobe gyri associated with V1, V2, and V3 of the visual cortex. Additionally, after accounting for age and sex variation, the relationship between ocular and total visual cortical volume was no longer statistically significant, but remained significantly related to total frontal lobe volume. The relationship between orbital and visual cortical volumes remained significant for a

  20. A Unified Framework for the Orbital Structure of Bars and Triaxial Ellipsoids

    NASA Astrophysics Data System (ADS)

    Valluri, Monica; Shen, Juntai; Abbott, Caleb; Debattista, Victor P.

    2016-02-01

    We examine a large random sample of orbits in two self-consistent simulations of N-body bars. Orbits in these bars are classified both visually and with a new automated orbit classification method based on frequency analysis. The well-known prograde x1 orbit family originates from the same parent orbit as the box orbits in stationary and rotating triaxial ellipsoids. However, only a small fraction of bar orbits (∼4%) have predominately prograde motion like their periodic parent orbit. Most bar orbits arising from the x1 orbit have little net angular momentum in the bar frame, making them equivalent to box orbits in rotating triaxial potentials. In these simulations a small fraction of bar orbits (∼7%) are long-axis tubes that behave exactly like those in triaxial ellipsoids: they are tipped about the intermediate axis owing to the Coriolis force, with the sense of tipping determined by the sign of their angular momentum about the long axis. No orbits parented by prograde periodic x2 orbits are found in the pure bar model, but a tiny population (∼2%) of short-axis tube orbits parented by retrograde x4 orbits are found. When a central point mass representing a supermassive black hole (SMBH) is grown adiabatically at the center of the bar, those orbits that lie in the immediate vicinity of the SMBH are transformed into precessing Keplerian orbits that belong to the same major families (short-axis tubes, long-axis tubes and boxes) occupying the bar at larger radii. During the growth of an SMBH, the inflow of mass and outward transport of angular momentum transform some x1 and long-axis tube orbits into prograde short-axis tubes. This study has important implications for future attempts to constrain the masses of SMBHs in barred galaxies using orbit-based methods like the Schwarzschild orbit superposition scheme and for understanding the observed features in barred galaxies.

  1. [Diseases of the orbit].

    PubMed

    Lukasik, S; Betkowski, A; Cyran-Rymarz, A; Szuber, D

    1995-01-01

    Diseases of the orbital cavity require more attention because of its specific anatomic structure and placement. Their curing requires cooperation of many medical specialties. Analysis consider orbital fractures, mainly caused by car accidents (69.2%). The next half of them consider inflammatory processes and tumor in equal numbers. Malignant tumors of orbital cavity occur most frequently (48.0%), less frequent are pseudotumors--pseudotumor orbitae (36.0%) and rare--malignant ones (16.0%). Malignant tumors more frequently infiltrate the orbit in neighborhood (63.3%), less frequently they come out from orbit tissue (16.7%). It should be emphasized that the number of orbit inflammations decreases in subsequent years, whereas occurrence of orbit tumors increases. PMID:9454170

  2. Bayesian Analysis of Multiple Populations in Galactic Globular Clusters

    NASA Astrophysics Data System (ADS)

    Wagner-Kaiser, Rachel A.; Sarajedini, Ata; von Hippel, Ted; Stenning, David; Piotto, Giampaolo; Milone, Antonino; van Dyk, David A.; Robinson, Elliot; Stein, Nathan

    2016-01-01

    We use GO 13297 Cycle 21 Hubble Space Telescope (HST) observations and archival GO 10775 Cycle 14 HST ACS Treasury observations of Galactic Globular Clusters to find and characterize multiple stellar populations. Determining how globular clusters are able to create and retain enriched material to produce several generations of stars is key to understanding how these objects formed and how they have affected the structural, kinematic, and chemical evolution of the Milky Way. We employ a sophisticated Bayesian technique with an adaptive MCMC algorithm to simultaneously fit the age, distance, absorption, and metallicity for each cluster. At the same time, we also fit unique helium values to two distinct populations of the cluster and determine the relative proportions of those populations. Our unique numerical approach allows objective and precise analysis of these complicated clusters, providing posterior distribution functions for each parameter of interest. We use these results to gain a better understanding of multiple populations in these clusters and their role in the history of the Milky Way.Support for this work was provided by NASA through grant numbers HST-GO-10775 and HST-GO-13297 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. This material is based upon work supported by the National Aeronautics and Space Administration under Grant NNX11AF34G issued through the Office of Space Science. This project was supported by the National Aeronautics & Space Administration through the University of Central Florida's NASA Florida Space Grant Consortium.

  3. A probabilistic analysis of the implications of instrument failures on ESA's Swarm mission for its individual satellite orbit deployments

    NASA Astrophysics Data System (ADS)

    Jackson, Andrew

    2015-07-01

    On launch, one of Swarm's absolute scalar magnetometers (ASMs) failed to function, leaving an asymmetrical arrangement of redundant spares on different spacecrafts. A decision was required concerning the deployment of individual satellites into the low-orbit pair or the higher "lonely" orbit. I analyse the probabilities for successful operation of two of the science components of the Swarm mission in terms of a classical probabilistic failure analysis, with a view to concluding a favourable assignment for the satellite with the single working ASM. I concentrate on the following two science aspects: the east-west gradiometer aspect of the lower pair of satellites and the constellation aspect, which requires a working ASM in each of the two orbital planes. I use the so-called "expert solicitation" probabilities for instrument failure solicited from Mission Advisory Group (MAG) members. My conclusion from the analysis is that it is better to have redundancy of ASMs in the lonely satellite orbit. Although the opposite scenario, having redundancy (and thus four ASMs) in the lower orbit, increases the chance of a working gradiometer late in the mission; it does so at the expense of a likely constellation. Although the results are presented based on actual MAG members' probabilities, the results are rather generic, excepting the case when the probability of individual ASM failure is very small; in this case, any arrangement will ensure a successful mission since there is essentially no failure expected at all. Since the very design of the lower pair is to enable common mode rejection of external signals, it is likely that its work can be successfully achieved during the first 5 years of the mission.

  4. De-Orbiting the International Space Station ISS: Safety Considerations and Preliminary Analysis

    NASA Astrophysics Data System (ADS)

    Cremaschi, F.; Huertas, I.; Ortega, G.; Sgobba, T.; Laurel, C.

    2012-01-01

    NASA has proposed to its partners the de-orbiting of the International Space Station (ISS) around the year 2020. Technical plans on how to do it have been presented as long as the year 1999. The current situation of ISS claims for a possible extension of the date of 2020 but to all International Partners is clear that the de-orbiting operations need to be performed with safety as the main and central paradigm. The proposed paper evaluates several scenarios and options for the de- orbiting of ISS. The paper proposes trajectory design considerations, de- orbit strategies and the calculation of casualties and fatalities for some of those. The paper proposes as well some fragment disposal regions using the classic approach of disposing ISS on ground and compares it with the feasibility and cost with the approach of end of life vehicle recycling culture of the European Union. The paper computes and calculates the reliability of all options and establishes a trade-off between all of them. The paper provides a detailed mathematical model that is able to calculate casualty and fatality rates. The mathematical model has been programmed in the ASTOS software tool and the corresponding casualty and fatality curves have been computed for some considered options. The following options are studied, discussed, and traded- off: simple one-go complete disposal of ISS with controlled de-orbiting using a service module, complex partial disposal of ISS elements with controlled de-orbiting using a modified version of service module, same variation using a set of auxiliary vehicles, design of a new vehicle to dispose the ISS and finally the uncontrolled re-entry of the entire ISS. Further, the paper proposes some de-orbiting requirements, and mission design considerations for a successful end-of-mission closure.

  5. GIS-based poverty and population distribution analysis in China

    NASA Astrophysics Data System (ADS)

    Cui, Jing; Wang, Yingjie; Yan, Hong

    2009-07-01

    Geographically, poverty status is not only related with social-economic factors but also strongly affected by geographical environment. In the paper, GIS-based poverty and population distribution analysis method is introduced for revealing their regional differences. More than 100000 poor villages and 592 national key poor counties are chosen for the analysis. The results show that poverty distribution tends to concentrate in most of west China and mountainous rural areas of mid China. Furthermore, the fifth census data are overlaid to those poor areas in order to gain its internal diversity of social-economic characteristics. By overlaying poverty related social-economic parameters, such as sex ratio, illiteracy, education level, percentage of ethnic minorities, family composition, finding shows that poverty distribution is strongly correlated with high illiteracy rate, high percentage minorities, and larger family member.

  6. Analysis of the Accuracy of Ballistic Descent from a Circular Circumterrestrial Orbit

    NASA Astrophysics Data System (ADS)

    Sikharulidze, Yu. G.; Korchagin, A. N.

    2002-01-01

    The problem of the transportation of the results of experiments and observations to Earth every so often appears in space research. Its simplest and low-cost solution is the employment of a small ballistic reentry spacecraft. Such a spacecraft has no system of control of the descent trajectory in the atmosphere. This can result in a large spread of landing points, which make it difficult to search for the spacecraft and very often a safe landing. In this work, a choice of a compromise scheme of the flight is considered, which includes the optimum braking maneuver, adequate conditions of the entry into the atmosphere with limited heating and overload, and also the possibility of landing within the limits of a circle with a radius of 12.5 km. The following disturbing factors were taken into account in the analysis of the accuracy of landing: the errors of the braking impulse execution, the variations of the atmosphere density and the wind, the error of the specification of the ballistic coefficient of the reentry spacecraft, and a displacement of its center of mass from the symmetry axis. It is demonstrated that the optimum maneuver assures the maximum absolute value of the reentry angle and the insensitivity of the trajectory of descent with respect to small errors of orientation of the braking engine in the plane of the orbit. It is also demonstrated that the possible error of the landing point due to the error of specification of the ballistic coefficient does not depend (in the linear approximation) upon its value and depends only upon the reentry angle and the accuracy of specification of this coefficient. A guided parachute with an aerodynamic efficiency of about two should be used at the last leg of the reentry trajectory. This will allow one to land in a prescribed range and to produce adequate conditions for the interception of the reentry spacecraft by a helicopter in order to prevent a rough landing.

  7. Independent component analysis of neural populations from multielectrode field potential measurements.

    PubMed

    Tanskanen, Jarno M A; Mikkonen, Jarno E; Penttonen, Markku

    2005-06-30

    Independent component analysis (ICA) is proposed for analysis of neural population activity from multichannel electrophysiological field potential measurements. The proposed analysis method provides information on spatial extents of active neural populations, locations of the populations with respect to each other, population evolution, including merging and splitting of populations in time, and on time lag differences between the populations. In some cases, results of the proposed analysis may also be interpreted as independent information flows carried by neurons and neural populations. In this paper, a detailed description of the analysis method is given. The proposed analysis is demonstrated with an illustrative simulation, and with an exemplary analysis of an in vivo multichannel recording from rat hippocampus. The proposed method can be applied in analysis of any recordings of neural networks in which contributions from a number of neural populations or information flows are simultaneously recorded via a number of measurement points, as well in vivo as in vitro. PMID:15922038

  8. Comparative Analysis of State Fish Consumption Advisories Targeting Sensitive Populations

    PubMed Central

    Scherer, Alison C.; Tsuchiya, Ami; Younglove, Lisa R.; Burbacher, Thomas M.; Faustman, Elaine M.

    2008-01-01

    Objective Fish consumption advisories are issued to warn the public of possible toxicological threats from consuming certain fish species. Although developing fetuses and children are particularly susceptible to toxicants in fish, fish also contain valuable nutrients. Hence, formulating advice for sensitive populations poses challenges. We conducted a comparative analysis of advisory Web sites issued by states to assess health messages that sensitive populations might access. Data sources We evaluated state advisories accessed via the National Listing of Fish Advisories issued by the U.S. Environmental Protection Agency. Data extraction We created criteria to evaluate advisory attributes such as risk and benefit message clarity. Data synthesis All 48 state advisories issued at the time of this analysis targeted children, 90% (43) targeted pregnant women, and 58% (28) targeted women of childbearing age. Only six advisories addressed single contaminants, while the remainder based advice on 2–12 contaminants. Results revealed that advisories associated a dozen contaminants with specific adverse health effects. Beneficial health effects of any kind were specifically associated only with omega-3 fatty acids found in fish. Conclusions These findings highlight the complexity of assessing and communicating information about multiple contaminant exposure from fish consumption. Communication regarding potential health benefits conferred by specific fish nutrients was minimal and focused primarily on omega-3 fatty acids. This overview suggests some lessons learned and highlights a lack of both clarity and consistency in providing the breadth of information that sensitive populations such as pregnant women need to make public health decisions about fish consumption during pregnancy. PMID:19079708

  9. Choice of population database for forensic DNA profile analysis.

    PubMed

    Steele, Christopher D; Balding, David J

    2014-12-01

    When evaluating the weight of evidence (WoE) for an individual to be a contributor to a DNA sample, an allele frequency database is required. The allele frequencies are needed to inform about genotype probabilities for unknown contributors of DNA to the sample. Typically databases are available from several populations, and a common practice is to evaluate the WoE using each available database for each unknown contributor. Often the most conservative WoE (most favourable to the defence) is the one reported to the court. However the number of human populations that could be considered is essentially unlimited and the number of contributors to a sample can be large, making it impractical to perform every possible WoE calculation, particularly for complex crime scene profiles. We propose instead the use of only the database that best matches the ancestry of the queried contributor, together with a substantial FST adjustment. To investigate the degree of conservativeness of this approach, we performed extensive simulations of one- and two-contributor crime scene profiles, in the latter case with, and without, the profile of the second contributor available for the analysis. The genotypes were simulated using five population databases, which were also available for the analysis, and evaluations of WoE using our heuristic rule were compared with several alternative calculations using different databases. Using FST=0.03, we found that our heuristic gave WoE more favourable to the defence than alternative calculations in well over 99% of the comparisons we considered; on average the difference in WoE was just under 0.2 bans (orders of magnitude) per locus. The degree of conservativeness of the heuristic rule can be adjusted through the FST value. We propose the use of this heuristic for DNA profile WoE calculations, due to its ease of implementation, and efficient use of the evidence while allowing a flexible degree of conservativeness. PMID:25498938

  10. Analysis of possible changes of the orbit of an asteroid approaching the Earth by impact of a spacecraft.

    NASA Astrophysics Data System (ADS)

    Ivashkin, V. V.; Zajtsev, A. V.

    1999-08-01

    As a part of analysis of guarding against the Earth's collision with an approaching asteroid the authors investigate the influence of kinetic impact of a spacecraft on the orbit of this asteroid. For an orbit of the Toutatis asteroid the global analysis of asteroid deflections (caused by the spacecraft impact) is carried out in the Earth's picture plane, depending on the spacecraft flight time and the moment of a spacecraft arrival to the asteroid. Locally optimal (with respect to the asteroid deflection) spacecraft trajectories are determined. The influence of the spacecraft initial mass on the limiting size of an asteroid, which is deflected from the Earth to a safe distance, is examined. The principal possibility of employing modern rocket-space systems for the spacecraft impact to prevent the Earth from colliding with an asteroid of a medium size is demonstrated.

  11. Genetic Profiling by Single-Nucleotide Polymorphism-Based Array Analysis Defines Three Distinct Subtypes of Orbital Meningioma

    PubMed Central

    Ho, Cheng-Ying; Mosier, Stacy; Safneck, Janice; Salomao, Diva R.; Miller, Neil R.; Eberhart, Charles G.; Gocke, Christopher D.; Batista, Denise A. S.; Rodriguez, Fausto J.

    2015-01-01

    Orbital meningiomas can be classified as primary optic nerve sheath (ON) meningiomas, primary intraorbital ectopic (Ob) meningiomas and spheno-orbital (Sph-Ob) meningiomas based on anatomic site. Single-nucleotide polymorphism (SNP)-based array analysis with the Illumina 300K platform was performed on formalin-fixed, paraffin-embedded tissue from 19 orbital meningiomas (5 ON, 4 Ob and 10 Sph-Ob meningiomas). Tumors were World Health Organization (WHO) grade I except for two grade II meningiomas, and one was NF2-associated. We found genomic alterations in 68% (13 of 19) of orbital meningiomas. Sph-Ob tumors frequently exhibited monosomy 22/22q loss (70%; 7/10) and deletion of chromosome 1p, 6q and 19p (50% each; 5/10). Among genetic alterations, loss of chromosome 1p and 6q were more frequent in clinically progressive tumors. Chromosome 22q loss also was detected in the majority of Ob meningiomas (75%; 3/4) but was infrequent in ON meningiomas (20%; 1/5). In general, Ob tumors had fewer chromosome alterations than Sph-Ob and ON tumors. Unlike Sph-Ob meningiomas, most of the Ob and ON meningiomas did not progress even after incomplete excision, although follow-up was limited in some cases. Our study suggests that ON, Ob and Sph-Ob meningiomas are three molecularly distinct entities. Our results also suggest that molecular subclassification may have prognostic implications. PMID:24773246

  12. Analysis of the Motion of the Extrasolar Planet HD 120136 Ab in a Binary System: Calculating Unknown Angular Orbital Elements

    NASA Astrophysics Data System (ADS)

    Plávalová, E.; Solovay, N. A.

    2015-07-01

    We have carried out an analysis of the motion of an extrasolar planet orbiting in a binary system, as a particular case of the three-body problem. The following assumptions have been made: a) the planet orbits around one of the binary components (the parent star); b) the distance between the stellar components is greater than that between the parent star and the orbiting planet (the ratio of the semi-major axes is a small parameter); c) the mass of the planet is smaller than the mass of the star, but is not negligible. We employed the Hamiltonian of the system without short-period terms, and we expanded it in terms of Legendre polynomials and truncated the expansion after the second-order terms. Such form of the Hamiltonian enables us to solve the differential equations of motion of our system and analyze of the motion of the extrasolar planet. We have applied this theory to the system HD 120136, and described the possible regions in which the planet can move. The theory permits us to calculate an unknown angular orbital element for the planet HD 120136 Ab, the ascending node: Ω1=134°±14°. The motion of the planet is expected to be stable over long time scales.

  13. Space shuttle engineering and operations support: Dispersion analysis for the first orbital flight test (OFT-1) mission

    NASA Technical Reports Server (NTRS)

    Snow, L. S.

    1977-01-01

    A dispersion analysis considering 3-sigma uncertainties (or perturbations) in platform, vehicle, and environmental parameters was performed for the first orbital flight test (OFT-1) mission. The dispersion analysis is based on the nominal trajectory for the OFT-1 reference flight profile. The analysis was performed to determine state vector and performance dispersions (or variations) which result from the indicated 3-sigma uncertainties. The dispersions are determined at major mission events and fixed times from liftoff (time slices). The dispersion results are used to evaluate the capability of the vehicle to perform the mission within a 3-sigma level of confidence and to determine flight performance reserves.

  14. Redesign and treatment planning orbital floor reconstruction using computer analysis anatomical landmarks.

    PubMed

    Ozer, Mehmet Asim; Govsa, Figen; Kazak, Zuhal; Erdogmus, Senem; Celik, Servet

    2016-08-01

    Orbital floor fractures are one of the most commonly encountered maxillofacial fractures due to their weak anatomical structure. Restoration of the orbital floor following a traumatic injury or a tumor surgery is often difficult due to inadequate visibility and lack of knowledge on its anatomical details. The aim of this study is to investigate the locations of the inferior orbital fissure (IOF), infraorbital groove (G), and infraorbital foramen (Fo) and their relationship with the orbital floor using a software. Measurements from the inferior orbital rim (IOR) using the Fo, the IOF, G, and the optic canal (OC) were calculated in 268 orbits as reference points. The surgical landmarks from the G and the OC, the G and the IOF, the G and the intersection point were measured as 31.6 ± 6, 12.9 ± 4, and 12 ± 5 mm, respectively. The mean distances between the G and the IOR, the Fo and the IOF, and the Fo and the OC were found as 8.3 ± 2.1, 28.7 ± 3.5, and 53.6 ± 5.9 mm, respectively. The mean angles were calculated as OC-IOF-G 68.1° ± 16.4°; intersection-G-IOF as 61.4° ± 15.8°; IOF-OC-G as 19° ± 5.5°; OC-G-intersection as 31.5° ± 11.9°, G-intersection-OC as 129.5°, IOF-intersection-G as 50.5°. Furthermore, variable bony changes on the orbital floor which may lead to the differences at intersection point of the G and Fo were determined. In 28 specimens (20.9 %), unilateral accessory Fo (AcFo) was present. In 27 specimens, AcFo was situated supermaedially (96.4 %) on the main aperture. In one specimen, two intraorbital canals and Fo emerged from different points and coursed into different apertures. The measured mean distances of the AcFo-IOR and the AcFo-Fo were as 7 ± 2 and 7.3 ± 3.2 mm, respectively. The primary principle in the oculoplastic treatment of orbital floor reconstructions must be repositioning the herniated orbital aperture by maintaining the infraorbital artery and the nerve in the orbital floor. The IOF and

  15. Analysis of stable periodic orbits in the one dimensional linear piecewise-smooth discontinuous map.

    PubMed

    Rajpathak, Bhooshan; Pillai, Harish K; Bandyopadhyay, Santanu

    2012-09-01

    In this paper, we consider one dimensional linear piecewise-smooth discontinuous maps. It is well known that stable periodic orbits exist for such maps, in some parameter region. It is also known that the corresponding bifurcation phenomena (termed as period adding bifurcation) exhibit a special structure. In the last couple of years, several authors have analyzed this structure using border collision bifurcation curves and given the characterization for various parameter regions. In this paper, we have analyzed a specific parameter range employing a different approach. We show that this approach enables one to pose some interesting questions like: what is the number of distinct periodic orbits of any given cardinality? We prove that there are precisely φ(n) distinct orbits of period n, where φ is the Euler's totient function. We propose an algorithm which calculates the location of fixed points of all these φ(n) distinct orbits and gives the precise range of existence of these orbits with respect to the parameters. Further, we show how the amount of computations required to find these ranges of existence can be optimized. PMID:23020465

  16. System technology analysis of aeroassisted orbital transfer vehicles - Moderate lift/drag

    NASA Technical Reports Server (NTRS)

    Florence, D. E.; Fischer, G.

    1983-01-01

    The utilization of procedures involving aerodynamic braking and/or aerodynamic maneuvering on return from higher altitude orbits to low-earth orbit makes it possible to realize significant performance benefits. The present study is concerned with a number of mission scenarios for Aeroassisted Orbital Transfer Vehicles (AOTV) and the impact of potential technology advances in the performance enhancement of the class of AOTV's having a hypersonic lift to drag ratio (L/D) of 0.75 to 1.5. It is found that the synergistic combination of a hypersonic L/D of 1.2, an advanced cryopropelled engine, and an LH2 drop tank (1-1/2 stage) leads to a single 65,000 pound shuttle, two-man geosynchronous mission with 2100 pounds of useful paylod. Additional payload enhancement is possible with AOTV dry weight reductions due to technology advances in the areas of vehicle structures and thermal protection systems and other subsystems.

  17. Maximization of orbiter altitude at ALT interface airspeed, mission planning, mission analysis and software

    NASA Technical Reports Server (NTRS)

    Glenn, G. M.

    1976-01-01

    The determination of the separation initial conditions (i.e. incidence angle) that maximize orbiter altitude at the ALT interface airspeed is considered. Optimum altitude airspeed profiles are generated for each orbiter incidence angle and tailcone configuration. Results show that the highest separation altitude does not result in the highest altitude at ALT interface airspeed. The altitude attainable at ALT interface airspeed should therefore be considered in the selection of the initial conditions (i.e. incidence angle). Without violating any known constraints, the incidence angles that maximize orbiter altitude at the ALT interface airspeeds are 7.0 deg for ALT free flight 1 and 5.5 deg for ALT free flight 6.

  18. Statistical Analysis of Interference Between Earth Stations and Earth-Orbiting Satellites

    NASA Technical Reports Server (NTRS)

    Bishop, D.

    1994-01-01

    Determination of the potential for radio frequency interference between Earth stations and orbiting spacecraft is often desirable. This information can be used to select frequencies for radio systems to avoid interference or it can be used to determine if coordination between radio systems is necessary. Also, it is useful for planning emission standards and filtering requirements for future telecommunications equipment. A model is developed that will determine the statistics of interference between Earth stations and elliptical orbiting spacecraft. The model uses orbital dynamics, detailed antenna patterns, and spectral characteristics to obtain accurate levels of interference at the victim receiver. The model is programmed into a computer simulation to obtain long term statistics of interference.

  19. Conceptual design and analysis of orbital cryogenic liquid storage and supply systems

    NASA Technical Reports Server (NTRS)

    Eberhardt, R. N.; Cunnington, G. R.; Johns, W. A.

    1981-01-01

    A wide variety of orbital cryogenic liquid storage and supply systems are defined in NASA and DOD long-range plans. These systems include small cooling applications, large chemical and electrical orbit transfer vehicles and supply tankers. All have the common requirements of low-g fluid management to accomplish gas-free liquid expulsion and efficient thermal control to manage heat leak and tank pressure. A preliminary design study was performed to evaluate tanks ranging from 0.6 to 37.4 cu m (22 to 1320 cu ft). Liquids of interest were hydrogen, oxygen, methane, argon and helium. Conceptual designs were generated for each tank system and fluid dynamic, thermal and structural analyses were performed for Shuttle compatible operations. Design trades considered the paradox of conservative support structure and minimum thermal input. Orbital performance and weight data were developed, and a technology evaluation was completed.

  20. An analysis of the basic population structure of Shanghai Municipality.

    PubMed

    Shen, A

    1984-01-01

    This paper analyzes the changes in Shanghai's population structure over the last 30 years in the 4 aspects of age structure, sex composition, urban and rural composition, and labor and employment structure. In 1953 those of the 0 to 6 age group accounted for 21.2% of the total population; in 1957 the group represented a proportion of 24.6%. Since the 1960s, especially after the 1970s, the family planning program gradually took effect, and the birthrate of the entire municipality fell drastically. The number of school-age children in 1979 was 1 1/2 times more than the same age group in 1953; there should be no worry that population control may result in a shortage of manpower to meet the needs of the work force and the armed forces either toward the end of this century or at the beginning of the next. The economy in China is underdeveloped, production and technology remain at a low level, average wages for employees are low, and for a long time the low living standard of the people has shown little sign of improvement. The problem is mainly manifest in the following areas: 1) distribution of the work force in heavy and light industries is not sufficiently rational, 2) the distribution of the work force between captial construction and transport and communications on the 1 hand and the national economy on the other is out of proportion, 3) the distribution of the work force between commerce, service trades, and public utilities on the 1 hand and the national economy on the other is disproportionated, and 4) the distribution of the work force between undertakings of culture, education, scientific research, health, and medical care on the 1 hand and economic construction on the other is improper. How to control population growth and adjust parts of the population structure to suit the national economic development poses a problem that calls for further in-depth study and analysis to resolve it step by step. PMID:12314770

  1. Analysis of Envisat Orbit Maintenance Strategies to Improve/Increase Envisat ASAR Interferometry Opportunities

    NASA Technical Reports Server (NTRS)

    Kuijper, D.; Matatoros, Garcia

    2007-01-01

    The biggest and most advanced Earth Observation Satellite in-orbit, developed by the European Space Agency (ESA) and its member states, is Envisat. It was launched on March 1, 2002 by an Ariane V from French Guyana and holds a total of 10 multi-disciplinary Earth observation instruments, among which an Advanced Synthetic Aperture Radar (ASAR). The ASAR user community requested the Flight Dynamics division of the European Space Operations Centre (ESOC) to investigate how the orbit control maintenance strategy for Envisat could be changed to optimize ASAR interferometry opportunities overall and in addition support the International Polar Year 2007/2008 initiative. The Polar Regions play a pivotal role in understanding our planet and our impact on it as they are recognized as sensitive barometers of environmental change. One of the main themes of the International Polar Year 2007/2008 is therefore the study of Earth s changing ice and snow, and its impact on our planet and our lives. Naturally, ESA would like to support this very important initiative. This paper presents the investigations that have been conducted to support these requests in the best possible way. It discusses the orbit maintenance strategy that has been in place since its launch, ensuring the actual orbit to be within 1 km of a so-called reference orbit, and presents the new orbit maintenance strategy that is aimed at improving/increasing the opportunities for Envisat ASAR interferometry, while preserving the fuel on board the spacecraft. The hydrazine on-board Envisat happens to be a precious resource as only approximately 300 kg of it was available at launch, like ERS-2. The difference being however that the mass of Envisat is approximately 3.2 times that of ERS-2.

  2. Analysis of error in TOMS total ozone as a function of orbit and attitude parameters

    NASA Technical Reports Server (NTRS)

    Gregg, W. W.; Ardanuy, P. E.; Braun, W. C.; Vallette, B. J.; Bhartia, P. K.; Ray, S. N.

    1991-01-01

    Computer simulations of orbital scenarios were performed to examine the effects of orbital altitude, equator crossing time, attitude uncertainty, and orbital eccentricity on ozone observations by future satellites. These effects were assessed by determining changes in solar and viewing geometry and earth daytime coverage loss. The importance of these changes on ozone retrieval was determined by simulating uncertainties in the TOMS ozone retrieval algorithm. The major findings are as follows: (1) Drift of equator crossing time from local noon would have the largest effect on the quality of ozone derived from TOMS. The most significant effect of this drift is the loss of earth daytime coverage in the winter hemisphere. The loss in coverage increases from 1 degree latitude for + or - 1 hour from noon, 6 degrees for + or - 3 hours from noon, to 53 degrees for + or - 6 hours from noon. An additional effect is the increase in ozone retrieval errors due to high solar zenith angles. (2) To maintain contiguous earth coverage, the maximum scan angle of the sensor must be increased with decreasing orbital altitude. The maximum scan angle required for full coverage at the equator varies from 60 degrees at 600 km altitude to 45 degrees at 1200 km. This produces an increase in spacecraft zenith angle, theta, which decreases the ozone retrieval accuracy. The range in theta was approximately 72 degrees for 600 km to approximately 57 degrees at 1200 km. (3) The effect of elliptical orbits is to create gaps in coverage along the subsatellite track. An elliptical orbit with a 200 km perigee and 1200 km apogee produced a maximum earth coverage gap of about 45 km at the perigee at nadir. (4) An attitude uncertainty of 0.1 degree in each axis (pitch, roll, yaw) produced a maximum scan angle to view the pole, and maximum solar zenith angle).

  3. Integrated orbital servicing study follow-on. Volume 2: Technical analysis and system design

    NASA Technical Reports Server (NTRS)

    1978-01-01

    In-orbit service functional and physical requirements to support both low and high Earth orbit servicing/maintenance operations were defined, an optimum servicing system configuration was developed and mockups and early prototype hardware were fabricated to demonstrate and validate the concepts selected. Significant issues addressed include criteria for concept selection; representative mission equipment and approaches to their design for serviceability; significant serviceable spacecraft design aspects; servicer mechanism operation in one-g; approaches for the demonstration/simulation; and service mechanism structure design approach.

  4. Experimental assessment of a computer program used in Space Shuttle orbiter entry heating analysis

    NASA Technical Reports Server (NTRS)

    Wells, W. L.; Hudgins, J.

    1983-01-01

    A high temperature reusable surface insulation (HRSI) tile taken from the Space Shuttle orbiter was subjected to a nominal heating rate of 60 kW/sq m in the laboratory. The surface temperature response to this heating was measured and used as input to a computer program which computed the applied heating rate. The program is part of a software system that is used to infer convective heating rates to the orbiter thermal protection system during entry. The measured and computed heating rates are compared. Results confirm the applicability of this program to the determination of flight heat transfer rates from flight measured surface temperature data.

  5. The Spectrum Orbit Utilization Program (SOUP) used for DBS plan analysis at RARC '83

    NASA Technical Reports Server (NTRS)

    Davidson, J.; Ottey, H. R.; Sawitz, P.; Zusman, F. S.

    1985-01-01

    This paper describes the history, functions, and usage of the program that was used to analyze the plans for direct broadcast satellite service developed in the course of the 1983 Regional Administrative Radio Conference for ITU Region 2. Given the requirements for direct broadcast service by the administrations, the conference delegates (1) developed the appropriate technical parameters; (2) made tentative assignments to the orbit locations, frequencies, and polarizations of space stations, (3) calculated the interferences and margins of such assignments through the use of the Spectrum Orbit Utilization Program (SOUP); and (4) iterated this procedure until an acceptable plan was found.

  6. Orbit to orbit transportation

    NASA Technical Reports Server (NTRS)

    Bergeron, R. P.

    1980-01-01

    Orbital transfer vehicle propulsion options for SPS include both chemical (COTV) and electrical (EOTV) options. The proposed EOTV construction method is similar to that of the SPS and, by the addition of a transmitting antenna, may serve as a demonstration or precursor satellite option. The results of the studies led to the selection of a single stage COTV for crew and priority cargo transfer. An EOTV concept is favored for cargo transfer because of the more favorable orbital burden factor over chemical systems. The gallium arsenide solar array is favored over the silicon array because of its self annealing characteristics of radiation damage encountered during multiple transitions through the Van Allen radiation belt. Transportation system operations are depicted. A heavy lift launch vehicle (HLLV) delivers cargo and propellants to LEO, which are transferred to a dedicated EOTV by means of an intraorbit transfer vehicle (IOTV) for subsequent transfer to GEO. The space shuttle is used for crew transfer from Earth to LEO. At the LEO base, the crew module is removed from the shuttle cargo bay and mated to a COTV for transfer to GEO. Upon arrival at GEO, the SPS construction cargo is transferred from the EOTV to the SPS construction base by IOTV. Crew consumables and resupply propellants are transported to GEO by the EOTV. Transportation requirements are dominated by the vast quantity of materials to be transported to LEO and GEO.

  7. A 3D Earth orbit model; visualization and analysis of Milankovitch cycles and insolation

    NASA Astrophysics Data System (ADS)

    Gilb, R. D.; Kostadinov, T. S.

    2012-12-01

    An astronomically precise and accurate Earth orbit graphical model, Earth orbit v2.0, is presented. The model offers 3D visualizations of Earth's orbital geometry, Milankovitch parameters and the ensuing insolation forcings. Prevalent paleoclimatic theories invoke Milankovitch cycles as a major forcing mechanism capable of shifting Earth's climate regimes on time scales of tens to hundreds of thousands of years. Variability of eccentricity (ellipticity of orbit), precession (longitude of perihelion) and obliquity (Earth's axial tilt) changes parameters such as amplitude of seasonal insolation, timing of seasons with respect to perihelion, and total annual insolation. Hays et al. (1976) demonstrated a strong link between Milankovitch cycles and paleoclimatological records, which has been confirmed and expanded many times since (e.g. Berger et al., 1994; Berger et al., 2010). The complex interplay of several orbital parameters on various time scales makes assessment and visualization of Earth's orbit and spatio-temporal insolation variability challenging. It is difficult to appreciate the pivotal importance of Kepler's laws of planetary motion in controlling the effects of Milankovitch cycles on insolation patterns on various spatio-temporal scales. These factors also make Milankovitch theory difficult to teach effectively. The model allows substantial user control in a robust, yet intuitive and user-friendly graphical user interface (GUI) developed in Matlab. We present the user with a choice between Berger et al. (1978) and Laskar et al. (2004) astronomical solutions for eccentricity, obliquity and precession. Berger solutions span from -1 Myr to +1 Myr, while Laskar provides solutions from -101 Myr to +21 Myr since J2000. Users can also choose a "demo" mode which allows the three Milankovitch parameters to be varied independently of each other, so the user can isolate the effects of each on orbital geometry and insolation. For example, extreme eccentricity can be

  8. Mixed dentition space analysis in a Thai population.

    PubMed

    Jaroontham, J; Godfrey, K

    2000-04-01

    This study produced simple linear regression equations to be used for mixed dentition space analysis for males and females, and sexes pooled in a population living in northeastern Thailand. Measurements of teeth were made to within 0.01 mm on the dental casts of 215 boys and 215 girls (mean age 15.7 years). All dentitions were required to be free of any signs of dental pathology or anomalies. It was found that males had significantly larger teeth than females as represented by summations of mandibular incisor, canine, and premolar widths. ANOVA of regression indicated a close relationship between mandibular incisor summation and corresponding summations of canine and premolars. The low coefficients of determination (r2) of the regressions ranged between 0.29 and 0.42, and were higher for females than males, which might be attributable to the ethnic diversity of the sampled population. The regression equations produced predictions of mesio-distal width summations for maxillary and mandibular canine, and premolar arch segments that were slightly different from other reported Asian studies. Moyers' prediction tables at the 50th percentile were found to under-estimate tooth size summation compared with the present investigation. The predictions from simplified regression equations matched well with those of this study for sexes pooled, and for males and females separately. PMID:10822885

  9. Validity of moyers mixed dentition analysis for Saudi population

    PubMed Central

    Al-Dlaigan, Yousef H.; Alqahtani, Nasser D.; Almoammar, Khalid; Al-Jewair, Thikriat; Salamah, Fahad Bin; Alswilem, Mohamme; Albarakati, Sahar F.

    2015-01-01

    Objectives: To evaluate the applicability of Moyers probability tables and to formulate more accurate mixed dentition prediction tables in the Saudi population. Methods: A cross-sectional study was conducted at the College of Dentistry, Kind Saud University, Saudi Arabia. The data were collected from 410 (203 males and 207 females) orthodontic study models, which had erupted mandibular permanent incisors, maxillary, mandibular canines and premolars. The mesiodistal widths were measured using a digital caliper with an accuracy of 0.01 mm. Student’s paired t-test was used to compare the mean width values derived from this study with the values derived using the Moyers table. Simple linear regression was used to evaluate the linear relationship between the combined mesiodistal widths of the mandibular permanent incisors and the canine-premolar segments in each dental arch. Results: The regression equations for the maxillary canine-premolar segment (males: Y=10.27+0.48X; females: Y=11.71 + 0.39X) and the mandibular canine-premolar segment (males: Y=9.71 + 0.40X; females: 11.28 + 0.39X) were used to formulate new probability tables on the Moyers pattern. Statistically significant differences were observed between predicted widths in our subjects and the widths obtained using Moyers tables. Conclusions: The new prediction tables derived in this study provided a more precise mixed dentition space analysis than Moyers prediction tables in estimating tooth dimensions in the Saudi population. PMID:26870104

  10. Population and genomic analysis of the genus Halorubrum

    PubMed Central

    Fullmer, Matthew S.; Soucy, Shannon M.; Swithers, Kristen S.; Makkay, Andrea M.; Wheeler, Ryan; Ventosa, Antonio; Gogarten, J. Peter; Papke, R. Thane

    2014-01-01

    The Halobacteria are known to engage in frequent gene transfer and homologous recombination. For stably diverged lineages to persist some checks on the rate of between lineage recombination must exist. We surveyed a group of isolates from the Aran-Bidgol endorheic lake in Iran and sequenced a selection of them. Multilocus Sequence Analysis (MLSA) and Average Nucleotide Identity (ANI) revealed multiple clusters (phylogroups) of organisms present in the lake. Patterns of intein and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) presence/absence and their sequence similarity, GC usage along with the ANI and the identities of the genes used in the MLSA revealed that two of these clusters share an exchange bias toward others in their phylogroup while showing reduced rates of exchange with other organisms in the environment. However, a third cluster, composed in part of named species from other areas of central Asia, displayed many indications of variability in exchange partners, from within the lake as well as outside the lake. We conclude that barriers to gene exchange exist between the two purely Aran-Bidgol phylogroups, and that the third cluster with members from other regions is not a single population and likely reflects an amalgamation of several populations. PMID:24782836

  11. Population genomic analysis of outcrossing and recombination in yeast.

    PubMed

    Ruderfer, Douglas M; Pratt, Stephen C; Seidel, Hannah S; Kruglyak, Leonid

    2006-09-01

    The budding yeast Saccharomyces cerevisiae has been used by humans for millennia to make wine, beer and bread. More recently, it became a key model organism for studies of eukaryotic biology and for genomic analysis. However, relatively little is known about the natural lifestyle and population genetics of yeast. One major question is whether genetically diverse yeast strains mate and recombine in the wild. We developed a method to infer the evolutionary history of a species from genome sequences of multiple individuals and applied it to whole-genome sequence data from three strains of Saccharomyces cerevisiae and the sister species Saccharomyces paradoxus. We observed a pattern of sequence variation among yeast strains in which ancestral recombination events lead to a mosaic of segments with shared genealogy. Based on sequence divergence and the inferred median size of shared segments (approximately 2,000 bp), we estimated that although any two strains have undergone approximately 16 million cell divisions since their last common ancestor, only 314 outcrossing events have occurred during this time (roughly one every 50,000 divisions). Local correlations in polymorphism rates indicate that linkage disequilibrium in yeast should extend over kilobases. Our results provide the initial foundation for population studies of association between genotype and phenotype in S. cerevisiae. PMID:16892060

  12. All-sky Meteor Orbit System AMOS and preliminary analysis of three unusual meteor showers

    NASA Astrophysics Data System (ADS)

    Tóth, Juraj; Kornoš, Leonard; Zigo, Pavol; Gajdoš, Štefan; Kalmančok, Dušan; Világi, Jozef; Šimon, Jaroslav; Vereš, Peter; Šilha, Jiří; Buček, Marek; Galád, Adrián; Rusňák, Patrik; Hrábek, Peter; Ďuriš, František; Rudawska, Regina

    2015-12-01

    All-sky Meteor Orbit System (AMOS) is a semi-autonomous video observatory for detection of transient events on the sky, mostly the meteors. Its hardware and software development and permanent placement on several locations in Slovakia allowed the establishment of Slovak Video Meteor Network (SVMN) monitoring meteor activity above the Central Europe. The data reduction, orbital determination and additional results from AMOS cameras - the SVMN database - as well as from observational expeditions on Canary Islands and in Canada provided dynamical and physical data for better understanding of mutual connections between parent bodies of asteroids and comets and their meteoroid streams. We present preliminary results on exceptional and rare meteor streams such as September ɛ Perseids (SPE) originated from unknown long periodic comet on a retrograde orbit, suspected asteroidal meteor stream of April α Comae Berenicids (ACO) in the orbit of meteorites Příbram and Neuschwanstein and newly observed meteor stream Camelopardalids (CAM) originated from Jupiter family comet 209P/Linear.

  13. Analysis of a Mars-stationary orbiting microwave power transmission system

    NASA Technical Reports Server (NTRS)

    Long, Kenwyn J.

    1990-01-01

    To determine the feasibility of providing efficient RF power transmission from a Mars-stationary orbit to the surface of the planet, an assessment was made focussing on RF propagation in the 2.45- to 300-GHz range. The proposed orbiting system configuration provides for power generation by either photovoltaic array or nuclear reactor, the conversion of the dc output to RF, and subsequent propagation of RF energy from the orbiting array to the Martian surface. On the planet, a rectenna array will convert RF to dc power to be distributed for planetary power needs. Total efficiency of the energy conversion chain from dc to RF in orbit through RF to dc on the planetary surface was derived for several representative frequencies in the range of study. Tradeoffs between component efficiency and transmitting antenna requirements were considered for each of these frequencies. Rectenna element power density thresholds and desired received power levels were used to determine receiving antenna criteria. Recommendations are presented for research into developing technologies which may afford enhanced viability of the proposed microwave power transmission system.

  14. Analysis of the Effect of UTI-UTC to High Precision Orbit

    NASA Astrophysics Data System (ADS)

    Shin, Dongseok; Kwak, Sunghee; Kim, Tag-Gon

    1999-12-01

    As the spatial resolution of remote sensing satellites becomes higher, very accurate determination of the position of a LEO (Low Earth Orbit) satellite is demanding more than ever. Non-symmetric Earth gravity is the major perturbation force to LEO satellites. Since the orbit propagation is performed in the celestial frame while Earth gravity is defined in the terrestrial frame, it is required to convert the coordinates of the satellite from one to the other accurately. Unless the coordinate conversion between the two frames is performed accurately the orbit propagation calculates incorrect Earth gravitational force at a specific time instant, and hence, causes errors in orbit prediction. The coordinate conversion between the two frames involves precession, nutation, Earth rotation and polar motion. Among these factors, unpredictability and uncertainty of Earth rotation, called UTI-UTC, is the largest error source. In this paper, the effect of UTI-UTC on the accuracy of the LEO propagation is introduced, tested and analzed. Considering the maximum unpredictability of UTI-UTC, 0.9 seconds, the meaningful order of non-spherical Earth harmonic functions is derived.

  15. Operations analysis (study 2.6). Volume 4: Computer specification; logistics of orbiting vehicle servicing (LOVES)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The logistics of orbital vehicle servicing computer specifications was developed and a number of alternatives to improve utilization of the space shuttle and the tug were investigated. Preliminary results indicate that space servicing offers a potential for reducing future operational and program costs over ground refurbishment of satellites. A computer code which could be developed to simulate space servicing is presented.

  16. Solar power satellite: Analysis of alternatives for transporting material to geosynchronous orbit

    NASA Technical Reports Server (NTRS)

    Graff, W. J.; Huang, C. J.

    1976-01-01

    A systems design study of the alternative methods and relative merits of various approaches to transporting and assembling a solar power satellite in geosynchronous orbit was conducted. State of the art alternatives for chemical and electrical interorbital propulsion were studied, and several possible scenarios for construction were proposed.

  17. Integrated orbital servicing and payloads study. Volume 2: Technical and cost analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The details and background used in the investigation of orbital servicing and payloads are presented. Topics discussed include review of previous models, application of servicing to communications satellites, assessment of spacecraft servicing, cost of servicing, and launch vehicle effects on spacecraft.

  18. On the properties of Se⋯N interaction: the analysis of substituent effects by energy decomposition and orbital interaction.

    PubMed

    Zhou, Fangfang; Liu, Ruirui; Tang, Jia; Li, Ping; Cui, Yahui; Zhang, Houyu

    2016-01-01

    The nature and strength of intermolecular Se⋯N interaction between selenium-containing compounds HSeX (X = CH3, NH2, CF3, OCH3, CN, OH, NO2, Cl, F), and NH3 have been investigated at the MP2/aug-cc-pVDZ level. The Se⋯N interaction is found to be dependent on the substituent groups, which greatly affect the positive electrostatic potential of Se atoms and the accepting electron ability of X-Se σ(∗) antibonding orbital. Energy decomposition of the Se ⋯N interaction reveals that electrostatic and induction forces are comparable in the weak-bonded complexes and induction becomes more significant in the complexes with strong electron-withdrawing substituents. Natural bond orbital (NBO) analysis indicates that the primary source of the induction is the electron transfer from the N lone pair to the X-Se σ(∗) antibonding orbital. The geometry of the complex and the interaction directionality of NH3 to X-Se bond can be regarded as a consequence of the exchange-repulsion. The topological analysis on the electron density reveals the nature of closed-shell interaction in these X-Se⋯N contacts. The Se⋯N interaction in the complexes with the strong electron-withdrawing substituent has a partly covalent character. PMID:26755190

  19. A 3D Visualization and Analysis Model of the Earth Orbit, Milankovitch Cycles and Insolation.

    NASA Astrophysics Data System (ADS)

    Kostadinov, Tihomir; Gilb, Roy

    2013-04-01

    Milankovitch theory postulates that periodic variability of Earth's orbital elements is a major climate forcing mechanism. Although controversies remain, ample geologic evidence supports the major role of the Milankovitch cycles in climate, e.g. glacial-interglacial cycles. There are three Milankovitch orbital parameters: orbital eccentricity (main periodicities of ~100,000 and ~400,000 years), precession (quantified as the longitude of perihelion, main periodicities 19,000-24,000 years) and obliquity of the ecliptic (Earth's axial tilt, main periodicity 41,000 years). The combination of these parameters controls the spatio-temporal patterns of incoming solar radiation (insolation) and the timing of the seasons with respect to perihelion, as well as season duration. The complex interplay of the Milankovitch orbital parameters on various time scales makes assessment and visualization of Earth's orbit and insolation variability challenging. It is difficult to appreciate the pivotal importance of Kepler's laws of planetary motion in controlling the effects of Milankovitch cycles on insolation patterns. These factors also make Earth-Sun geometry and Milankovitch theory difficult to teach effectively. Here, an astronomically precise and accurate Earth orbit visualization model is presented. The model offers 3D visualizations of Earth's orbital geometry, Milankovitch parameters and the ensuing insolation forcings. Both research and educational uses are envisioned for the model, which is developed in Matlab® as a user-friendly graphical user interface (GUI). We present the user with a choice between the Berger et al. (1978) and Laskar et al. (2004) astronomical solutions for eccentricity, obliquity and precession. A "demo" mode is also available, which allows the three Milankovitch parameters to be varied independently of each other (and over much larger ranges than the naturally occurring ones), so the user can isolate the effects of each parameter on orbital geometry

  20. Comparing G: multivariate analysis of genetic variation in multiple populations.

    PubMed

    Aguirre, J D; Hine, E; McGuigan, K; Blows, M W

    2014-01-01

    The additive genetic variance-covariance matrix (G) summarizes the multivariate genetic relationships among a set of traits. The geometry of G describes the distribution of multivariate genetic variance, and generates genetic constraints that bias the direction of evolution. Determining if and how the multivariate genetic variance evolves has been limited by a number of analytical challenges in comparing G-matrices. Current methods for the comparison of G typically share several drawbacks: metrics that lack a direct relationship to evolutionary theory, the inability to be applied in conjunction with complex experimental designs, difficulties with determining statistical confidence in inferred differences and an inherently pair-wise focus. Here, we present a cohesive and general analytical framework for the comparative analysis of G that addresses these issues, and that incorporates and extends current methods with a strong geometrical basis. We describe the application of random skewers, common subspace analysis, the 4th-order genetic covariance tensor and the decomposition of the multivariate breeders equation, all within a Bayesian framework. We illustrate these methods using data from an artificial selection experiment on eight traits in Drosophila serrata, where a multi-generational pedigree was available to estimate G in each of six populations. One method, the tensor, elegantly captures all of the variation in genetic variance among populations, and allows the identification of the trait combinations that differ most in genetic variance. The tensor approach is likely to be the most generally applicable method to the comparison of G-matrices from any sampling or experimental design. PMID:23486079

  1. Analysis of optimal and near-optimal continuous-thrust transfer problems in general circular orbit

    NASA Astrophysics Data System (ADS)

    Kéchichian, Jean A.

    2009-09-01

    A pair of practical problems in optimal continuous-thrust transfer in general circular orbit is analyzed within the context of analytic averaging for rapid computations leading to near-optimal solutions. The first problem addresses the minimum-time transfer between inclined circular orbits by proposing an analytic solution based on a split-sequence strategy in which the equatorial inclination and node controls are done separately by optimally selecting the intermediate orbit size at the sequence switch point that results in the minimum-time transfer. The consideration of the equatorial inclination and node state variables besides the orbital velocity variable is needed to further account for the important J2 perturbation that precesses the orbit plane during the transfer, unlike the thrust-only case in which it is sufficient to consider the relative inclination and velocity variables thus reducing the dimensionality of the system equations. Further extensions of the split-sequence strategy with analytic J2 effect are thus possible for equal computational ease. The second problem addresses the maximization of the equatorial inclination in fixed time by adopting a particular thrust-averaging scheme that controls only the inclination and velocity variables, leaving the node at the mercy of the J2 precession, providing robust fast-converging codes that lead to efficient near-optimal solutions. Example transfers for both sets of problems are solved showing near-optimal features as far as transfer time is concerned, by directly comparing the solutions to "exact" purely numerical counterparts that rely on precision integration of the raw unaveraged system dynamics with continuously varying thrust vector orientation in three-dimensional space.

  2. Population viability analysis of the Endangered shortnose sturgeon

    SciTech Connect

    Jager, Yetta; Bevelhimer, Mark S; Peterson, Douglas L.

    2011-07-01

    This study used population viability analysis (PVA) to partition the influences of potential threats to the endangered shortnose sturgeon (Acipenser brevirostrum). A workshop brought together experts to help identify potential threats including groundwater withdrawal, poor water quality, saltwater intrusion, mercury effects, harvest as by-catch, and sedimentation of spawning habitat. During the course of the project, we eliminated some threats and added new ones. Groundwater withdrawal was dismissed after a study failed to identify connection with groundwater and the majority of pumping is from a confined aquifer. We also eliminated activities on Fort Stewart as influences on spawning habitat because any successful spawning must occur upstream of Fort Stewart. We added climate change to the list of threats based on our assessment of temperature effects and expectations of sea-level rise. Our study highlighted the role of populations in nearby rivers in providing metapopulation support, raising the concern that the population in the Ogeechee River acts as a demographic sink. As part of this study, we carried out a field sampling study to analyze effects of training activities on headwater streams. We developed a new methodology for sampling design as part of this effort and used a mixed-modeling approach to identify relationships between land cover-land use, including those associated with military training activity and water quality. We found that tank training was associated with higher suspended sediment and equipment training was associated with higher organic carbon) and water quality. We detected effects of training on suspended sediment and organic carbon. We also carried out a field sampling effort in the Canoochee and Ogeechee Rivers. In the Ogeechee River, we found that dissolved oxygen in 40% of measurements during summer were below 4 mg L-1. To evaluate mercury as a potential threat, we developed a mercury uptake model and analyzed mercury levels in

  3. The analysis of single-electron orbits in a free electron laser based upon a rectangular hybrid wiggler

    NASA Astrophysics Data System (ADS)

    Kordbacheh, A.; Ghahremaninezhad, Roghayeh; Maraghechi, B.

    2012-09-01

    A three-dimensional analysis of a novel free-electron laser (FEL) based upon a rectangular hybrid wiggler (RHW) is presented. This RHW is designed in a configuration composed of rectangular rings with alternating ferrite and dielectric spacers immersed in a solenoidal magnetic field. An analytic model of RHW is introduced by solution of Laplace's equation for the magnetostatic fields under the appropriate boundary conditions. The single-electron orbits in combined RHW and axial guide magnetic fields are studied when only the first and the third spatial harmonic components of the RHW field are taken into account and the higher order terms are ignored. The results indicate that the third spatial harmonic leads to group III orbits with a strong negative mass regime particularly in large solenoidal magnetic fields. RHW is found to be a promising candidate with favorable characteristics to be used in microwave FEL.

  4. A new release of the mean orbital motion theory, and a new tool provided by CNES for long term analysis of disposal orbits and re-entry predictions

    NASA Astrophysics Data System (ADS)

    Deleflie, Florent; Wailliez, Sébastien; Portmann, Christophe; Gilles, M.; Vienne, Alain; Berthier, J.; Valk, St; Hautesserres, Denis; Martin, Thierry; Fraysse, Hubert

    To perform an orbit modelling accurate enough to provide a good estimate of the lifetime of a satellite, or to ensure the stability of a disposal orbit through centuries, we built a new orbit propagator based on the theory of mean orbital motion. It is named SECS-SD2 , for Simplified and Extended CODIOR Software -Space Debris Dedicated . The CODIOR software propagates numerically averaged equations of motion, with a typical integration step size on the order of a few hours, and was originally written in classical orbital elements. The so-called Space Debris -dedicated version is written in orbital elements suitable for orbits with small eccentricities and inclinations, so as to characterize the main dynamic properties of the motion within the LEO, MEO, and GEO regions. The orbital modelling accounts for the very first terms of the geopotential, the perturbations induced by the luni-solar attraction, the solar radiation pressure, and the atmospheric drag (using classical models). The new software was designed so as to ensure short computation times, even over periods of decades or centuries. This paper aims first at describing and validating the main functionalities of the software: we explain how the simplified averaged equations of motion were built, we show how we get sim-plified luni-solar ephemerides without using any huge file for orbit propagations over centuries, and we show how we averaged and simulated the solar flux. We show as well how we expressed short periodic terms to be added to the mean equations of motion, in order to get orbital ele-ments comparable to those deduced from the classical numerical integration of the oscultating equations of motion. The second part of the paper sheds light on some dynamical properties of space debris flying in the LEO and GEO regions, which were obtained from the new software. Knowing that each satellite in the LEO region is now supposed to re-enter the atmosphere within a period of 25 years, we estimated in various

  5. Orbital pseudotumor

    MedlinePlus

    ... Names Idiopathic orbital inflammatory syndrome (IOIS) Images Skull anatomy References Goodlick TA, Kay MD, Glaser JS, Tse DT, Chang WJ. Orbital disease and neuro-ophthalmology. In: Tasman W, Jaeger EA, eds. Duane’s ...

  6. Kepler's Orbit

    NASA Video Gallery

    Kepler does not orbit the Earth, rather it orbits the Sun in concert with the Earth, slowly drifting away from Earth. Every 61 Earth years, Kepler and Earth will pass by each other. Throughout the ...

  7. Orbital cellulitis

    MedlinePlus

    ... Haemophilus influenzae B) vaccine. The bacteria Staphylococcus aureus , Streptococcus pneumoniae , and beta-hemolytic streptococci may also cause orbital cellulitis. Orbital cellulitis infections in children may get worse very quickly and can lead ...

  8. Removal of orbital debris

    NASA Technical Reports Server (NTRS)

    Petro, Andrew J.; Talent, David L.

    1989-01-01

    The several methods presently identified for the reduction of orbital debris populations are broadly classifiable as either preventive or remedial, and fall within distinctive operational regimes. For all particles, (1) in the 250-2000-km altitude band, intelligent sweepers may be used; (2) for large objects, in the 80-250-km altitude band, orbital decay renders removal impractical; (3) for the 250-750-km altitude band, deorbit devices should be used; (4) for 750-2500-km altitude, OMV rendezvous for propulsive deorbit package attachment is foreseeable; and beyond 2500 km, (5) propulsive escape from earth orbit is required.

  9. WetLab-2: Tools for Conducting On-Orbit Quantitative Real-Time Gene Expression Analysis on ISS

    NASA Technical Reports Server (NTRS)

    Parra, Macarena; Almeida, Eduardo; Boone, Travis; Jung, Jimmy; Schonfeld, Julie

    2014-01-01

    The objective of NASA Ames Research Centers WetLab-2 Project is to place on the ISS a research platform capable of conducting gene expression analysis via quantitative real-time PCR (qRT-PCR) of biological specimens sampled or cultured on orbit. The project has selected a Commercial-Off-The-Shelf (COTS) qRT-PCR system, the Cepheid SmartCycler and will fly it in its COTS configuration. The SmartCycler has a number of advantages including modular design (16 independent PCR modules), low power consumption, rapid ramp times and the ability to detect up to four separate fluorescent channels at one time enabling multiplex assays that can be used for normalization and to study multiple genes of interest in each module. The team is currently working with Cepheid to enable the downlink of data from the ISS to the ground and provide uplink capabilities for programming, commanding, monitoring, and instrument maintenance. The project has adapted commercial technology to design a module that can lyse cells and extract RNA of sufficient quality and quantity for use in qRT-PCR reactions while using a housekeeping gene to normalize RNA concentration and integrity. The WetLab-2 system is capable of processing multiple sample types ranging from microbial cultures to animal tissues dissected on-orbit. The ability to conduct qRT-PCR on-orbit eliminates the confounding effects on gene expression of reentry stresses and shock acting on live cells and organisms or the concern of RNA degradation of fixed samples. The system can be used to validate terrestrial analyses of samples returned from ISS by providing on-orbit gene expression benchmarking prior to sample return. The ability to get on orbit data will provide investigators with the opportunity to adjust experiment parameters for subsequent trials based on the real-time data analysis without need for sample return and re-flight. Researchers will also be able to sample multigenerational changes in organisms. Finally, the system can be

  10. Stellar populations in ω Centauri: a multivariate analysis

    NASA Astrophysics Data System (ADS)

    Fraix-Burnet, D.; Davoust, E.

    2015-07-01

    We have performed multivariate statistical analyses of photometric and chemical abundance parameters of three large samples of stars in the globular cluster ω Centauri. The statistical analysis of a sample of 735 stars based on seven chemical abundances with the method of Maximum Parsimony (cladistics) yields the most promising results: seven groups are found, distributed along three branches with distinct chemical, spatial and kinematical properties. A progressive chemical evolution can be traced from one group to the next, but also within groups, suggestive of an inhomogeneous chemical enrichment of the initial interstellar matter. The adjustment of stellar evolution models shows that the groups with metallicities [Fe/H] > -1.5 are Helium enriched, thus presumably of second generation. The spatial concentration of the groups increases with chemical evolution, except for two groups, which stand out in their other properties as well. The amplitude of rotation decreases with chemical evolution, except for two of the three metal-rich groups, which rotate fastest, as predicted by recent hydrodynamical simulations. The properties of the groups are interpreted in terms of star formation in gas clouds of different origins. In conclusion, our multivariate analysis has shown that metallicity alone cannot segregate the different populations of ω Centauri.

  11. Analytical determination of orbital elements using Fourier analysis. I. The radial velocity case

    NASA Astrophysics Data System (ADS)

    Delisle, J.-B.; Ségransan, D.; Buchschacher, N.; Alesina, F.

    2016-05-01

    We describe an analytical method for computing the orbital parameters of a planet from the periodogram of a radial velocity signal. The method is very efficient and provides a good approximation of the orbital parameters. The accuracy is mainly limited by the accuracy of the computation of the Fourier decomposition of the signal which is sensitive to sampling and noise. Our method is complementary with more accurate (and more expensive in computer time) numerical algorithms (e.g. Levenberg-Marquardt, Markov chain Monte Carlo, genetic algorithms). Indeed, the analytical approximation can be used as an initial condition to accelerate the convergence of these numerical methods. Our method can be applied iteratively to search for multiple planets in the same system.

  12. Analysis of Formation Flying in Eccentric Orbits Using Linearized Equations of Relative Motion

    NASA Technical Reports Server (NTRS)

    Lane, Christopher; Axelrad, Penina

    2004-01-01

    Geometrical methods for formation flying design based on the analytical solution to Hill's equations have been previously developed and used to specify desired relative motions in near circular orbits. By generating relationships between the vehicles that are intuitive, these approaches offer valuable insight into the relative motion and allow for the rapid design of satellite configurations to achieve mission specific requirements, such as vehicle separation at perigee or apogee, minimum separation, or a specific geometrical shape. Furthermore, the results obtained using geometrical approaches can be used to better constrain numerical optimization methods; allowing those methods to converge to optimal satellite configurations faster. This paper presents a set of geometrical relationships for formations in eccentric orbits, where Hill.s equations are not valid, and shows how these relationships can be used to investigate formation designs and how they evolve with time.

  13. Aeroheating Analysis for the Mars Reconnaissance Orbiter with Comparison to Flight Data

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.

    2007-01-01

    The aeroheating environment of the Mars Reconnaissance Orbiter (MRO) has been analyzed using the direct simulation Monte Carlo and free-molecular techniques. The results of these analyses were used to develop an aeroheating database to be used for the preflight planning and the in-flight operations support for the aerobraking phase of the MRO mission. The aeroheating predictions calculated for the MRO include the heat transfer coefficient (CH) over a range of angles-of-attack, sideslip angles, and number densities. The effects of flow chemistry, surface temperature, and surface grid resolution were also investigated to determine the aeroheating database uncertainties. Flight heat flux data has been calculated from surface temperature sensor data returned to Earth from the MRO in orbit around Mars during the aerobraking phase of its mission. The heat flux data have been compared to the aeroheating database and agree favorably.

  14. Precision Analysis Based on Complicated Error Simulation for the Orbit Determination with the Space Tracking Ship

    NASA Astrophysics Data System (ADS)

    Lei, YANG; Caifa, GUO; Zhengxu, DAI; Xiaoyong, LI; Shaolin, WANG

    2016-02-01

    The space tracking ship is a moving platform in the TT&C network. The orbit determination precision of the ship plays a key role in the TT&C mission. Based on the measuring data obtained by the ship-borne equipments, the paper presents the mathematic models of the complicated error from the space tracking ship, which can separate the random error and the correction residual error with secondary low frequency from the complicated error. An error simulation algorithm is proposed to analyze the orbit determination precision based on the two set of the different equipments. With this algorithm, a group of complicated error can be simulated from a measured sample. The simulated error groups can meet the requirements of sufficient complicated error for the equipment tests before the mission execution, which is helpful to the practical application.

  15. Analysis of quasi-hybrid solid rocket booster concepts for advanced earth-to-orbit vehicles

    NASA Technical Reports Server (NTRS)

    Zurawski, Robert L.; Rapp, Douglas C.

    1987-01-01

    A study was conducted to assess the feasibility of quasi-hybrid solid rocket boosters for advanced Earth-to-orbit vehicles. Thermochemical calculations were conducted to determine the effect of liquid hydrogen addition, solids composition change plus liquid hydrogen addition, and the addition of an aluminum/liquid hydrogen slurry on the theoretical performance of a PBAN solid propellant rocket. The space shuttle solid rocket booster was used as a reference point. All three quasi-hybrid systems theoretically offer higher specific impulse when compared with the space shuttle solid rocket boosters. However, based on operational and safety considerations, the quasi-hybrid rocket is not a practical choice for near-term Earth-to-orbit booster applications. Safety and technology issues pertinent to quasi-hybrid rocket systems are discussed.

  16. EVA Design, Verification, and On-Orbit Operations Support Using Worksite Analysis

    NASA Technical Reports Server (NTRS)

    Hagale, Thomas J.; Price, Larry R.

    2000-01-01

    The International Space Station (ISS) design is a very large and complex orbiting structure with thousands of Extravehicular Activity (EVA) worksites. These worksites are used to assemble and maintain the ISS. The challenge facing EVA designers was how to design, verify, and operationally support such a large number of worksites within cost and schedule. This has been solved through the practical use of computer aided design (CAD) graphical techniques that have been developed and used with a high degree of success over the past decade. The EVA design process allows analysts to work concurrently with hardware designers so that EVA equipment can be incorporated and structures configured to allow for EVA access and manipulation. Compliance with EVA requirements is strictly enforced during the design process. These techniques and procedures, coupled with neutral buoyancy underwater testing, have proven most valuable in the development, verification, and on-orbit support of planned or contingency EVA worksites.

  17. Analytical and numerical approaches of a solar array thermal analysis in a low-earth orbit satellite

    NASA Astrophysics Data System (ADS)

    Kim, Hui Kyung; Han, Cho Young

    2010-12-01

    This paper researches the thermal analysis of a fixed-type solar array in a low-earth orbit satellite through both an analytical method with a simplified thermal model and a numerical method with a detailed thermal model. An analytical solution is derived from the simplified one-dimensional thermal governing equation. Because the current solar array is thermally decoupled from the spacecraft bus, its thermal analysis can be performed independently. The worst hot temperature of the current solar array can be predicted using an analytical solution of a single-lumped mass node. For better solar cell efficiency, a thermal surface finish of the backside of a solar array is required to ensure that the solar array temperature remains as low as possible in orbit. There are four ideal thermal surface types for a thermal surface finish. Based on the analytical solutions of the solar array temperature under the worst hot condition corresponding to each ideal thermal surface type, a solar reflector type gives the lowest temperature. Thus, SG121FD white paint was selected as an actual application of a thermal surface finish. A detailed solar array thermal model included in the system-level satellite thermal model was developed and solved numerically. From the detailed thermal analysis, in-orbit thermal characteristics of the solar array were determined and the thermal safety of the current solar array was verified with satisfying the allowable temperature limits. And the usefulness of the analytical approach to predict the worst hot temperature of the current solar array was also confirmed in comparison with the numerical analysis result of the detailed thermal model.

  18. Analysis of erosion and transportation features from lunar orbiter and Apollo photography

    NASA Technical Reports Server (NTRS)

    Gold, T.

    1980-01-01

    Certain classes of surface features in Lunar Orbiter and Apollo Panoramic Photographs are identifed and possible correlations between the occurrence of these features and their geographical location on the Moon are studied. Whether evidence of erosion and transport processes not encountered on Earth exists is investigated using the lunar photographs. The variety and intensity of transport processes on the Moon resulting from exposure to plasmas is discussed.

  19. Scout: short-arc orbit analysis and hazard assessment for newly discovered asteroids

    NASA Astrophysics Data System (ADS)

    Farnocchia, Davide; Chesley, Steven R.; Micheli, Marco

    2016-05-01

    It typically takes a few days for a newly discovered asteroid to be officially recognized as a real object. This time is needed to collect additional data and make sure the observations belong to an actual asteroid rather than being an artifact or corresponding to an artificial object. However, asteroids could experience an Earth close approach or even an impact only a few days or less after the discovery observations, as in the cases of 2008 TC3 and 2014 AA, i.e., the only two asteroids discovered before an Earth impact. In such cases, a rapid identification of the close approach or impact dramatically improves the chances of securing the asteroid's trajectory with additional observations prior to impact. Scout is an automated system that provides an orbital and hazard assessment for new potential asteroid discoveries within minutes after the observations are available. Since the time interval covered by the observations is generally short, perhaps only a few hours or even less, there are severe degeneracies in the orbit estimation process. To overcome these degeneracies Scout relies on systematic ranging, a technique that scans the poorly constrained space of topocentric range and range rate, while the plane-of-sky position and motion are directly tied to the recorded observations. This scan allows us to identify the possible orbits and the regions corresponding to collision solutions, as well as potential impact times and locations. From the probability distribution of the observation errors, Scout derives a probability distribution in the orbital space and in turn estimates several metrics of interest, e.g., probability of an Earth impact, of a close approach to Earth, and of being a mission-accessible target.

  20. VIIRS On-Orbit Optical Anomaly - Investigation, Analysis, Root Cause Determination and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Iona, Glenn; Butler, James; Guenther, Bruce; Graziani, Larissa; Johnson, Eric; Kennedy, Brian; Kent, Criag; Lambeck, Robert; Waluschka, Eugne; Xiong, Xiaoxiong

    2012-01-01

    A gradual, but persistent, decrease in the optical throughput was detected during the early commissioning phase for the Suomi National Polar-Orbiting Partnership (SNPP) Visible Infrared Imager Radiometer Suite (VIIRS) Near Infrared (NIR) bands. Its initial rate and unknown cause were coincidently coupled with a decrease in sensitivity in the same spectral wavelength of the Solar Diffuser Stability Monitor (SDSM) raising concerns about contamination or the possibility of a system-level satellite problem. An anomaly team was formed to investigate and provide recommendations before commissioning could resume. With few hard facts in hand, there was much speculation about possible causes and consequences of the degradation. Two different causes were determined as will be explained in this paper. This paper will describe the build and test history of VIIRS, why there were no indicators, even with hindsight, of an on-orbit problem, the appearance of the on-orbit anomaly, the initial work attempting to understand and determine the cause, the discovery of the root cause and what Test-As-You-Fly (TAYF) activities, can be done in the future to greatly reduce the likelihood of similar optical anomalies. These TAYF activities are captured in the lessons learned section of this paper.

  1. Pseudo-symmetry analysis of the d-block molecular orbitals in four-coordinate complexes.

    PubMed

    Falceto, Andrés; Casanova, David; Alemany, Pere; Alvarez, Santiago

    2013-06-01

    A rigorous definition of the concept of pseudo-symmetry, which is as important to chemistry as the concepts of symmetry implemented through group theory, should allow us to apply those group theoretical tools to molecules that are significantly distorted from those ideal symmetries best known and understood by the chemical community. In this paper, we consider four-coordinate transition-metal complexes with geometries along the interconversion path between the square and the tetrahedron and show how their molecular orbitals can be expressed in terms of either the tetrahedral or tetragonal symmetry groups. Furthermore, we analyze how the intensity of a d-d absorption band can be related to the degree of symmetry loss of the d-block molecular orbitals by means of their decomposition in terms of contributions from different pseudo-symmetry representations. As a final example, we also show how the substitution of a single ligand in a square planar complex affects the symmetry of the molecular orbitals and the absorption intensity associated to an electronic transition. PMID:23668721

  2. Nonlinear analysis of a large-orbit coaxial-waveguide cyclotron autoresonance maser amplifier

    SciTech Connect

    Ouyang Zhengbiao; Zhang Shichang

    2007-10-01

    Nonlinear simulations are presented to analyze the influences of the electron beam and the magnetic field parameters on the output power of a large-orbit coaxial-waveguide cyclotron autoresonance maser (CARM) amplifier. It is found that the guiding-center spread of the relativistic electrons has negligible impact on the output power due to the small field change felt by the large-orbit electrons. The electron-beam velocity spread and energy spread substantially decrease the output power, because these spreads directly affect the beam-wave interaction through the Doppler term and the relativistic cyclotron frequency term in the cyclotron resonance condition. However, this adverse effect may be offset by properly tapering the operating magnetic field. The output power is sensitive to both the slope and the amplitude of the tapered magnetic field. Nonlinear simulation demonstrates the feasibility that a large-orbit coaxial-waveguide CARM amplifier can be expected to provide output power with several megawatts, ultrahigh gain, and good bandwidth in the millimeter and submillimeter wavelength ranges.

  3. VIIRS on-orbit optical anomaly: investigation, analysis, root cause determination and lessons learned

    NASA Astrophysics Data System (ADS)

    Iona, Glenn; Butler, James; Guenther, Bruce; Graziani, Larissa; Johnson, Eric; Kennedy, Brian; Kent, Craig; Lambeck, Robert; Waluschka, Eugene; Xiong, Xiaoxiong

    2012-09-01

    A gradual, but persistent, decrease in the optical throughput was detected during the early commissioning phase for the Suomi National Polar-Orbiting Partnership (SNPP) Visible Infrared Imager Radiometer Suite (VIIRS) Near Infrared (NIR) bands. Its initial rate and unknown cause were coincidently coupled with a decrease in sensitivity in the same spectral wavelength of the Solar Diffuser Stability Monitor (SDSM) raising concerns about contamination or the possibility of a system-level satellite problem. An anomaly team was formed to investigate and provide recommendations before commissioning could resume. With few hard facts in hand, there was much speculation about possible causes and consequences of the degradation. Two different causes were determined as will be explained in this paper. This paper will describe the build and test history of VIIRS, why there were no indicators, even with hindsight, of an on-orbit problem, the appearance of the on-orbit anomaly, the initial work attempting to understand and determine the cause, the discovery of the root cause and what Test-As-You-Fly (TAYF) activities, can be done in the future to greatly reduce the likelihood of similar optical anomalies. These TAYF activities are captured in the "lessons learned" section of this paper.

  4. Orbital transfer vehicle concept definition and system analysis study. Volume 1A: Executive summary. Phase 2

    NASA Technical Reports Server (NTRS)

    Ketchum, W. J.

    1986-01-01

    The objectives of the Phase 2 study were to improve the orbit transfer vehicle (OTV) concept definition by focusing on the following issues: the impact of mission requirements on OTV system design; OTV basing concepts on the Space Shuttle, separate platforms, and/or remote locations; cost reduction of an OTV program to improve its economic benefits and support its acquisition. The OTV mission scenario includes a wide range of missions the main drivers of which are manned GEO servicing, mid-inclination/polar DOD, and lunar/planetary projects. A mission model is presented which includes the type and number of missions per year and the estimated propellant requirements. To accomplish the missions, many OTV concepts were defined including ground-based OTVs launched either in the STS orbiter, the aft cargo carrier, or a heavy lift launch vehicle, and a space-based OTV. System and program trade studies were conducted using performance, cost, safety/risk, and operations/growth criteria. The study shows that mission requirements and substantial economic benefits justify a reusable, cryogenic (H2/O2) space-based OTV. Such a system would not be subjected to Earth-to-orbit launch loads and would not be constained in size or weight. Safety is enhanced by the fact that the system components are launched unfueled. Its inherent reusability and ability to be refueled in space make the space-based OTV very economical to operate.

  5. Energy Decomposition Analysis Based on Absolutely Localized Molecular Orbitals for Large-Scale Density Functional Theory Calculations in Drug Design.

    PubMed

    Phipps, M J S; Fox, T; Tautermann, C S; Skylaris, C-K

    2016-07-12

    We report the development and implementation of an energy decomposition analysis (EDA) scheme in the ONETEP linear-scaling electronic structure package. Our approach is hybrid as it combines the localized molecular orbital EDA (Su, P.; Li, H. J. Chem. Phys., 2009, 131, 014102) and the absolutely localized molecular orbital EDA (Khaliullin, R. Z.; et al. J. Phys. Chem. A, 2007, 111, 8753-8765) to partition the intermolecular interaction energy into chemically distinct components (electrostatic, exchange, correlation, Pauli repulsion, polarization, and charge transfer). Limitations shared in EDA approaches such as the issue of basis set dependence in polarization and charge transfer are discussed, and a remedy to this problem is proposed that exploits the strictly localized property of the ONETEP orbitals. Our method is validated on a range of complexes with interactions relevant to drug design. We demonstrate the capabilities for large-scale calculations with our approach on complexes of thrombin with an inhibitor comprised of up to 4975 atoms. Given the capability of ONETEP for large-scale calculations, such as on entire proteins, we expect that our EDA scheme can be applied in a large range of biomolecular problems, especially in the context of drug design. PMID:27248370

  6. Independent Orbiter Assessment (IOA): Analysis of the electrical power generation/power reactant storage and distribution subsystem

    NASA Technical Reports Server (NTRS)

    Gotch, S. M.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NAA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Electrical Power Generation (EPG)/Power Reactants Storage and Distribution (PRSD) System Hardware is documented. The EPG/PRSD hardware is required for performing critical functions of cryogenic hydrogen and oxygen storage and distribution to the Fuel Cell Powerplants (FCP) and Atmospheric Revitalization Pressure Control Subsystem (ARPCS). Specifically, the EPG/PRSD hardware consists of the following: Hydryogen (H2) tanks; Oxygen (O2) tanks; H2 Relief Valve/Filter Packages (HRVFP); O2 Relief Valve/Filter Packages (ORVFP); H2 Valve Modules (HVM); O2 Valve Modules (OVM); and O2 and H2 lines, components, and fittings.

  7. Monte Carlo analysis of the Titan III/Transfer Orbit Stage guidance system for the Mars Observer mission

    NASA Technical Reports Server (NTRS)

    Bell, Stephen C.; Ginsburg, Marc A.; Rao, Prabhakara P.

    1993-01-01

    An important part of space launch vehicle mission planning for a planetary mission is the integrated analysis of guidance and performance dispersions for both booster and upper stage vehicles. For the Mars Observer mission, an integrated trajectory analysis was used to maximize the scientific payload and to minimize injection errors by optimizing the energy management of both vehicles. This was accomplished by designing the Titan III booster vehicle to inject into a hyperbolic departure plane, and the Transfer Orbit Stage (TOS) to correct any booster dispersions. An integrated Monte Carlo analysis of the performance and guidance dispersions of both vehicles provided sensitivities, an evaluation of their guidance schemes and an injection error covariance matrix. The polynomial guidance schemes used for the Titan III variable flight azimuth computations and the TOS solid rocket motor ignition time and burn direction derivations accounted for a wide variation of launch times, performance dispersions, and target conditions. The Mars Observer spacecraft was launched on 25 September 1992 on the Titan III/TOS vehicle. The post flight analysis indicated that a near perfect park orbit injection was achieved, followed by a trans-Mars injection with less than 2sigma errors.

  8. Adaptively resizing populations: Algorithm, analysis, and first results

    NASA Technical Reports Server (NTRS)

    Smith, Robert E.; Smuda, Ellen

    1993-01-01

    Deciding on an appropriate population size for a given Genetic Algorithm (GA) application can often be critical to the algorithm's success. Too small, and the GA can fall victim to sampling error, affecting the efficacy of its search. Too large, and the GA wastes computational resources. Although advice exists for sizing GA populations, much of this advice involves theoretical aspects that are not accessible to the novice user. An algorithm for adaptively resizing GA populations is suggested. This algorithm is based on recent theoretical developments that relate population size to schema fitness variance. The suggested algorithm is developed theoretically, and simulated with expected value equations. The algorithm is then tested on a problem where population sizing can mislead the GA. The work presented suggests that the population sizing algorithm may be a viable way to eliminate the population sizing decision from the application of GA's.

  9. How amino and nitro substituents direct electrophilic aromatic substitution in benzene: an explanation with Kohn-Sham molecular orbital theory and Voronoi deformation density analysis.

    PubMed

    Stasyuk, O A; Szatylowicz, H; Krygowski, T M; Fonseca Guerra, C

    2016-04-28

    The substituent effect of the amino and nitro groups on the electronic system of benzene has been investigated quantum chemically using quantitative Kohn-Sham molecular orbital theory and a corresponding energy decomposition analysis (EDA). The directionality of electrophilic substitution in aniline can accurately be explained with the amount of contribution of the 2pz orbitals on the unsubstituted carbon atoms to the highest occupied π orbital. For nitrobenzene, the molecular π orbitals cannot explain the regioselectivity of electrophilic substitution as there are two almost degenerate π orbitals with nearly the same 2pz contributions on the unsubstituted carbon atoms. The Voronoi deformation density analysis has been applied to aniline and nitrobenzene to obtain an insight into the charge rearrangements due to the substituent. This analysis method identified the orbitals involved in the C-N bond formation of the π system as the cause for the π charge accumulation at the ortho and para positions in the case of the NH2 group and the largest charge depletion at these same positions for the NO2 substituent. Furthermore, we showed that it is the repulsive interaction between the πHOMO of the phenyl radical and the πHOMO of the NH2 radical that is responsible for pushing up the πHOMO of aniline and therefore activating this π orbital of the phenyl ring towards electrophilic substitution. PMID:26800159

  10. Declining scaup populations: A retrospective analysis of long-term population and harvest survey data

    USGS Publications Warehouse

    Afton, A.D.; Anderson, M.G.

    2001-01-01

    We examined long-term databases concerning population status of scaup (lesser [Aythya affinis] and greater scaup [A. marila] combined) and harvest statistics of lesser scaup to identify factors potentially limiting population growth. Specifically, we explored evidence for and against the general hypotheses that scaup populations have declined in association with declining recruitment and/or female survival. We examined geographic heterogeneity in scaup demographic patterns that could yield evidence about potential limiting factors. Several biases exist in survey methodology used to estimate scaup populations and harvest statistics; however, none of these biases likely accounted for our major findings that (1) the continental scaup breeding population has declined over the last 20 years, with widespread and consistent declines within surveyed areas of the Canadian western boreal forest where most lesser scaup breed; (2) sex ratios of lesser scaup in the U.S. harvest have increased (more males now relative to females); and (3) age ratios of lesser scaup in the U.S. harvest have declined (fewer immatures now relative to adults), especially in the midcontinent region. We interpreted these major findings as evidence that (1) recruitment of lesser scaup has declined over the last 20 years, particularly in the Canadian western boreal forest; and (2) survival of female lesser scaup has declined relative to that of males. We found little evidence that harvest was associated with the scaup population decline. Our findings underscore the need for both improvements and changes to population survey procedures and new research to discriminate among various hypotheses explaining the recent scaup population decline.

  11. Inbreeding effective population size and parentage analysis without parents.

    PubMed

    Waples, Robin S; Waples, Ryan K

    2011-03-01

    An important use of genetic parentage analysis is the ability to directly calculate the number of offspring produced by each parent (k(i)) and hence effective population size, N(e). But what if parental genotypes are not available? In theory, given enough markers, it should be possible to reconstruct parental genotypes based entirely on a sample of progeny, and if so the vector of parental k(i) values. However, this would provide information only about parents that actually contributed offspring to the sample. How would ignoring the 'null' parents (those that produced no offspring) affect an estimate of N(e)? The surprising answer is that null parents have no effect at all. We show that: (i) The standard formula for inbreeding N(e) can be rewritten so that it is a function only of sample size and ∑(k(2)(i)); it is not necessary to know the total number of parents (N). This same relationship does not hold for variance N(e). (ii) This novel formula provides an unbiased estimate of N(e) even if only a subset of progeny is available, provided the parental contributions are accurately determined, in which case precision is also high compared to other single-sample estimators of N(e). (iii) It is not necessary to actually reconstruct parental genotypes; from a matrix of pairwise relationships (as can be estimated by some current software programs), it is possible to construct the vector of k(i) values and estimate N(e). The new method based on parentage analysis without parents (PwoP) can potentially be useful as a single-sample estimator of contemporary N(e), provided that either (i) relationships can be accurately determined, or (ii) ∑(k(2)(i)) can be estimated directly. PMID:21429172

  12. Phylogeographic Analysis of Mitochondrial DNA in Northern Asian Populations

    PubMed Central

    Derenko, Miroslava ; Malyarchuk, Boris ; Grzybowski, Tomasz ; Denisova, Galina ; Dambueva, Irina ; Perkova, Maria ; Dorzhu, Choduraa ; Luzina, Faina ; Lee, Hong Kyu ; Vanecek, Tomas ; Villems, Richard ; Zakharov, Ilia 

    2007-01-01

    To elucidate the human colonization process of northern Asia and human dispersals to the Americas, a diverse subset of 71 mitochondrial DNA (mtDNA) lineages was chosen for complete genome sequencing from the collection of 1,432 control-region sequences sampled from 18 autochthonous populations of northern, central, eastern, and southwestern Asia. On the basis of complete mtDNA sequencing, we have revised the classification of haplogroups A, D2, G1, M7, and I; identified six new subhaplogroups (I4, N1e, G1c, M7d, M7e, and J1b2a); and fully characterized haplogroups N1a and G1b, which were previously described only by the first hypervariable segment (HVS1) sequencing and coding-region restriction-fragment–length polymorphism analysis. Our findings indicate that the southern Siberian mtDNA pool harbors several lineages associated with the Late Upper Paleolithic and/or early Neolithic dispersals from both eastern Asia and southwestern Asia/southern Caucasus. Moreover, the phylogeography of the D2 lineages suggests that southern Siberia is likely to be a geographical source for the last postglacial maximum spread of this subhaplogroup to northern Siberia and that the expansion of the D2b branch occurred in Beringia ∼7,000 years ago. In general, a detailed analysis of mtDNA gene pools of northern Asians provides the additional evidence to rule out the existence of a northern Asian route for the initial human colonization of Asia. PMID:17924343

  13. Population pharmacokinetic analysis of Ibuprofen enantiomers in preterm newborn infants.

    PubMed

    Gregoire, Nicolas; Desfrere, Luc; Roze, Jean-Christophe; Kibleur, Yves; Koehne, Petra

    2008-12-01

    The aim of this pharmacokinetic analysis was to develop and validate a population pharmacokinetic model for R- and S-ibuprofen from samples obtained after 3 successive administrations of ibuprofen (10-5-5 mg/kg) at 24-hour intervals to preterm newborn infants aged from <6 hours to 8 days of life. A model including unilateral bioconversion of R-ibuprofen into S-ibuprofen was developed using the software NONMEM. R- and S-ibuprofen plasma concentrations were adequately fitted by this model. Estimated clearance and volume of distribution were 3.5 mL/h/kg and 173 mL/kg, respectively, with a calculated half-life (t((1/2))) of 34.3 hours for S-ibuprofen. Estimated clearance at birth and volume of distribution were 25.5 mL/h/kg and 306 mL/kg with a t((1/2)) at birth of 8.3 hours for R-ibuprofen. R-ibuprofen elimination increased during the first week of life, whereas S-ibuprofen pharmacokinetics were weakly modified. Therefore, because the activity of the 2 enantiomers differs, it is important that subsequent studies consider R- and S-enantiomers separately. Mean simulated ibuprofen concentrations at various dose regimens were in agreement with observed concentrations. The present analysis allows a more accurate estimation of the ibuprofen pharmacokinetics as parameters could be estimated separately for each enantiomer and the effect of postnatal age on the elimination of R-ibuprofen was elicited. PMID:18796580

  14. Computational Fluid Dynamics Analysis for the Orbiter LH2 Feedline Flowliner

    NASA Technical Reports Server (NTRS)

    Kiris, Cetin C.

    2005-01-01

    In phase II, additional inducer rotations are simulated in order to understand the root cause of the flowliner crack problem. CFD results confirmed that there is a strong unsteady interaction between the backflow regions caused by the LPFTP inducer and secondary flow regions in the bellows cavity through the flowliner slots. It is observed that the swirl on the duct side of the downstream flowliner is stronger than on the duct side of the upstream flowliner. Due to this swirl, there are more significant unsteady flow interactions through the downstream slots than those observed in the upstream slots. Averaged values of the local velocity at the slots were provided to the NESC-ITA flow physics acoustics team to guide them in designing the acoustics experiment. A parametric study was performed to compare the flow field in the flowliner area when one upstream slot and one corresponding downstream slot were enlarged. No significant differences were observed between the flow field obtained from the enlarged slot configuration when compared with the original configuration. More cases must be analyzed with various enlarged slot configurations to generalize this observation. The flow through the A1 test stand and the flow through the orbiter fuel feedline manifold were simulated without the LPFTP. It was observed that incoming flow to the flowliner and inducer was more uniform in the A1 test stand then in the orbiter manifold. Additionally, each engine LPFTP in the orbiter receives significantly different velocity distributions. Because of the differences observed in the computed results, it is not possible for the A1 test stand to represent the three different engine feedlines simultaneously.

  15. Analysis of the Shuttle Orbiter reinforced carbon-carbon oxidation protection system

    NASA Technical Reports Server (NTRS)

    Williams, S. D.; Curry, Donald M.; Chao, Dennis; Pham, Vuong T.

    1994-01-01

    Reusable, oxidation-protected reinforced carbon-carbon (RCC) has been successfully flown on all Shuttle Orbiter flights. Thermal testing of the silicon carbide-coated RCC to determine its oxidation characteristics has been performed in convective (plasma Arc-Jet) heating facilities. Surface sealant mass loss was characterized as a function of temperature and pressure. High-temperature testing was performed to develop coating recession correlations for predicting performance at the over-temperature flight conditions associated with abort trajectories. Methods for using these test data to establish multi-mission re-use (i.e., mission life) and single mission limits are presented.

  16. Analysis of orbital occupancy of valence neutron in {sup 15}C through Coulomb breakup reactions

    SciTech Connect

    Singh, P. E-mail: pardeep.phy@dcrustm.org

    2015-03-15

    The Coulomb breakup reactions {sup 208}Pb({sup 15}C, {sup 14}C + n){sup 208}Pb and {sup 181}Ta({sup 15}C, {sup 14}C + n){sup 181}Ta have been studied at 68 and 85 A MeV beam energies, respectively, within the framework of the eikonal approximation to investigate the orbital occupancy of valence neutron in the {sup 15}C nucleus. The outcomes of the present work favor 0{sup +} ⊗ 2s{sub 1/2} as the core-neutron coupling for the ground-state structure with 0.91 as a spectroscopic factor.

  17. An initial analysis of the data from the Polar Orbiting Geophysical (POGS) Satellite

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Sabaka, T. J.; Baldwin, R. T.

    1991-01-01

    The Polar Orbiting Geophysical Satellite (POGS) was launched in 1990 to measure the geomagnetic field. POGS data from selected magnetically quiet days was chosen, quality checked and deleted where thought to be erroneous. A time and position correction was applied. The resulting data was fit to a degree 13 spherical harmonic model. Evaluation of the quality of the data indicates that it is sufficient for definition of the low degree (approximately less than 8) portion of the geomagnetic field. Further correction of the data time and position may improve this quality.

  18. Orbital transfer vehicle concept definition and system analysis study, 1985. Volume 3: System and program trades

    NASA Technical Reports Server (NTRS)

    Nelson, James H.; Mohrman, Gordon W.; Callan, Daniel R.

    1986-01-01

    The key system and program trade studies performed to arrive at a preferred Orbital Transfer Vehicle (OTV) system concept and evolutionary approach to the acquisition of the requisite capabilites is documented. These efforts were expanded to encompass a Space Transportation Architecture Study (STAS) mission model and recommended unmanned cargo vehicle. The most important factors affecting the results presented are the mission model requirements and selection criteria. The reason for conducting the OTV concept definition and system analyses study is to select a concept and acquisition approach that meets a delivery requirement reflected by the mission model.

  19. A microarray analysis of two distinct lymphatic endothelial cell populations

    PubMed Central

    Schweighofer, Bernhard; Rohringer, Sabrina; Pröll, Johannes; Holnthoner, Wolfgang

    2015-01-01

    We have recently identified lymphatic endothelial cells (LECs) to form two morphologically different populations, exhibiting significantly different surface protein expression levels of podoplanin, a major surface marker for this cell type. In vitro shockwave treatment (IVSWT) of LECs resulted in enrichment of the podoplaninhigh cell population and was accompanied by markedly increased cell proliferation, as well as 2D and 3D migration. Gene expression profiles of these distinct populations were established using Affymetrix microarray analyses. Here we provide additional details about our dataset (NCBI GEO accession number GSE62510) and describe how we analyzed the data to identify differently expressed genes in these two LEC populations. PMID:26484194

  20. Metatranscriptomic Analysis of Groundwater Reveals an Active Anammox Bacterial Population

    NASA Astrophysics Data System (ADS)

    Jewell, T. N. M.; Karaoz, U.; Thomas, B. C.; Banfield, J. F.; Brodie, E.; Williams, K. H.; Beller, H. R.

    2014-12-01

    Groundwater is a major natural resource, yet little is known about the contribution of microbial anaerobic ammonium oxidation (anammox) activity to subsurface nitrogen cycling. During anammox, energy is generated as ammonium is oxidized under anaerobic conditions to dinitrogen gas, using nitrite as the final electron acceptor. This process is a global sink for fixed nitrogen. Only a narrow range of monophyletic bacteria within the Planctomycetes carries out anammox, and the full extent of their metabolism, and subsequent impact on nitrogen cycling and microbial community structure, is still unknown. Here, we employ a metatranscriptomic analysis on enriched mRNA to identify the abundance and activity of a population of anammox bacteria within an aquifer at Rifle, CO. Planktonic biomass was collected over a two-month period after injection of up to 1.5 mM nitrate. Illumina-generated sequences were mapped to a phylogenetically binned Rifle metagenome database. We identified transcripts for genes with high protein sequence identities (81-98%) to those of anammox strain KSU-1 and to two of the five anammox bacteria genera, Brocadia and Kuenenia, suggesting an active, if not diverse, anammox population. Many of the most abundant anammox transcripts mapped to a single scaffold, indicative of a single dominant anammox species. Transcripts of the genes necessary for the anammox pathway were present, including an ammonium transporter (amtB), nitrite/formate transporter, nitrite reductase (nirK), and hydrazine oxidoreductase (hzoB). The form of nitrite reductase encoded by anammox is species-dependent, and we only identified nirK, with no evidence of anammox nirS. In addition to the anammox pathway we saw evidence of the anammox bacterial dissimilatory nitrate reduction to ammonium pathway (narH, putative nrfA, and nrfB), which provides an alternate means of generating substrates for anammox from nitrate, rather than relying on an external pool. Transcripts for hydroxylamine