Control system design and analysis using the INteractive Controls Analysis (INCA) program

Science.gov (United States)

Bauer, Frank H.; Downing, John P.

1987-01-01

The INteractive Controls Analysis (INCA) program was developed at the Goddard Space Flight Center to provide a user friendly efficient environment for the design and analysis of linear control systems. Since its inception, INCA has found extensive use in the design, development, and analysis of control systems for spacecraft, instruments, robotics, and pointing systems. Moreover, the results of the analytic tools imbedded in INCA have been flight proven with at least three currently orbiting spacecraft. This paper describes the INCA program and illustrates, using a flight proven example, how the package can perform complex design analyses with relative ease.

GAUSSIAN 76: an ab initio molecular orbital program

International Nuclear Information System (INIS)

Binkley, J.S.; Whiteside, R.; Hariharan, P.C.; Seeger, R.; Hehre, W.J.; Lathan, W.A.; Newton, M.D.; Ditchfield, R.; Pople, J.A.

Gaussian 76 is a general-purpose computer program for ab initio Hartree-Fock molecular orbital calculations. It can handle basis sets involving s, p and d-type gaussian functions. Certain standard sets (STO-3G, 4-31G, 6-31G*, etc.) are stored internally for easy use. Closed shell (RHF) or unrestricted open shell (UHF) wave functions can be obtained. Facilities are provided for geometry optimization to potential minima and for limited potential surface scans

Academy of Program/Project & Engineering Leadership Orbital Debris Management and Risk Mitigation

Data.gov (United States)

National Aeronautics and Space Administration — The NASA Academy of Program/Project & Engineering Leadership (APPEL) is excited to announce the public release of Orbital Debris Management and Risk Mitigation,...

Uncertainty Requirement Analysis for the Orbit, Attitude, and Burn Performance of the 1st Lunar Orbit Insertion Maneuver

Directory of Open Access Journals (Sweden)

Young-Joo Song

2016-12-01

Full Text Available In this study, the uncertainty requirements for orbit, attitude, and burn performance were estimated and analyzed for the execution of the 1st lunar orbit insertion (LOI maneuver of the Korea Pathfinder Lunar Orbiter (KPLO mission. During the early design phase of the system, associate analysis is an essential design factor as the 1st LOI maneuver is the largest burn that utilizes the onboard propulsion system; the success of the lunar capture is directly affected by the performance achieved. For the analysis, the spacecraft is assumed to have already approached the periselene with a hyperbolic arrival trajectory around the moon. In addition, diverse arrival conditions and mission constraints were considered, such as varying periselene approach velocity, altitude, and orbital period of the capture orbit after execution of the 1st LOI maneuver. The current analysis assumed an impulsive LOI maneuver, and two-body equations of motion were adapted to simplify the problem for a preliminary analysis. Monte Carlo simulations were performed for the statistical analysis to analyze diverse uncertainties that might arise at the moment when the maneuver is executed. As a result, three major requirements were analyzed and estimated for the early design phase. First, the minimum requirements were estimated for the burn performance to be captured around the moon. Second, the requirements for orbit, attitude, and maneuver burn performances were simultaneously estimated and analyzed to maintain the 1st elliptical orbit achieved around the moon within the specified orbital period. Finally, the dispersion requirements on the B-plane aiming at target points to meet the target insertion goal were analyzed and can be utilized as reference target guidelines for a mid-course correction (MCC maneuver during the transfer. More detailed system requirements for the KPLO mission, particularly for the spacecraft bus itself and for the flight dynamics subsystem at the ground

Scripting Module for the Satellite Orbit Analysis Program (SOAP)

Science.gov (United States)

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

Space-based solar power conversion and delivery systems study. Volume 2: Engineering analysis of orbital systems

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Vibrational study and Natural Bond Orbital analysis of serotonin in monomer and dimer states by density functional theory

Science.gov (United States)

Borah, Mukunda Madhab; Devi, Th. Gomti

2018-06-01

The vibrational spectral analysis of Serotonin and its dimer were carried out using the Fourier Transform Infrared (FTIR) and Raman techniques. The equilibrium geometrical parameters, harmonic vibrational wavenumbers, Frontier orbitals, Mulliken atomic charges, Natural Bond orbitals, first order hyperpolarizability and some optimized energy parameters were computed by density functional theory with 6-31G(d,p) basis set. The detailed analysis of the vibrational spectra have been carried out by computing Potential Energy Distribution (PED, %) with the help of Vibrational Energy Distribution Analysis (VEDA) program. The second order delocalization energies E(2) confirms the occurrence of intramolecular Charge Transfer (ICT) within the molecule. The computed wavenumbers of Serotonin monomer and dimer were found in good agreement with the experimental Raman and IR values.

Economic analysis requirements in support of orbital debris regulatory policy

Science.gov (United States)

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.

On-Orbit Quantitative Real-Time Gene Expression Analysis Using the Wetlab-2 System

Science.gov (United States)

Parra, Macarena; Jung, Jimmy; Almeida, Eduardo; Boone, Travis; Tran, Luan; Schonfeld, Julie

2015-01-01

NASA Ames Research Center's WetLab-2 Project enables on-orbit quantitative Reverse Transcriptase PCR (qRT-PCR) analysis without the need for sample return. The WetLab-2 system is capable of processing sample types ranging from microbial cultures to animal tissues dissected on-orbit. The project developed a RNA preparation module that can lyse cells and extract RNA of sufficient quality and quantity for use as templates in qRT-PCR reactions. Our protocol has the advantage of using non-toxic chemicals and does not require alcohols or other organics. The resulting RNA is dispensed into reaction tubes that contain all lyophilized reagents needed to perform qRT-PCR reactions. System operations require simple and limited crew actions including syringe pushes, valve turns and pipette dispenses. The project selected the Cepheid SmartCycler (TradeMark), a Commercial-Off-The-Shelf (COTS) qRT-PCR unit, because of its advantages including rugged modular design, low power consumption, rapid thermal ramp times and four-color multiplex detection. Single tube multiplex assays can be used to normalize for RNA concentration and integrity, and to study multiple genes of interest in each module. The WetLab-2 system can downlink data from the ISS to the ground after a completed run and uplink new thermal cycling programs. The ability to conduct qRT-PCR and generate results on-orbit is an important step towards utilizing the ISS as a National Laboratory facility. Specifically, the ability to get on-orbit data will provide investigators with the opportunity to adjust experimental parameters in real time without the need for sample return and re-flight. On orbit gene expression analysis can also eliminate 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 and provide on-orbit gene expression benchmarking prior to sample return. Finally, the system can also be used for analysis of

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

Directory of Open Access Journals (Sweden)

Ha–Yeon Choi

2015-12-01

Full Text Available 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.

PyORBIT: A Python Shell For ORBIT

Energy Technology Data Exchange (ETDEWEB)

Jean-Francois Ostiguy; Jeffrey Holmes

2003-07-01

ORBIT is code developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. The code is structured as a collection of external C++ modules for SuperCode, a high level interpreter shell developed at LLNL in the early 1990s. SuperCode is no longer actively supported and there has for some time been interest in replacing it by a modern scripting language, while preserving the feel of the original ORBIT program. In this paper, we describe a new version of ORBIT where the role of SuperCode is assumed by Python, a free, well-documented and widely supported object-oriented scripting language. We also compare PyORBIT to ORBIT from the standpoint of features, performance and future expandability.

PyORBIT: A Python Shell For ORBIT

International Nuclear Information System (INIS)

Jean-Francois Ostiguy; Jeffrey Holmes

2003-01-01

ORBIT is code developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. The code is structured as a collection of external C++ modules for SuperCode, a high level interpreter shell developed at LLNL in the early 1990s. SuperCode is no longer actively supported and there has for some time been interest in replacing it by a modern scripting language, while preserving the feel of the original ORBIT program. In this paper, we describe a new version of ORBIT where the role of SuperCode is assumed by Python, a free, well-documented and widely supported object-oriented scripting language. We also compare PyORBIT to ORBIT from the standpoint of features, performance and future expandability

Demonstrating High-Accuracy Orbital Access Using Open-Source Tools

Science.gov (United States)

Gilbertson, Christian; Welch, Bryan

2017-01-01

Orbit propagation is fundamental to almost every space-based analysis. Currently, many system analysts use commercial software to predict the future positions of orbiting satellites. This is one of many capabilities that can replicated, with great accuracy, without using expensive, proprietary software. NASAs SCaN (Space Communication and Navigation) Center for Engineering, Networks, Integration, and Communications (SCENIC) project plans to provide its analysis capabilities using a combination of internal and open-source software, allowing for a much greater measure of customization and flexibility, while reducing recurring software license costs. MATLAB and the open-source Orbit Determination Toolbox created by Goddard Space Flight Center (GSFC) were utilized to develop tools with the capability to propagate orbits, perform line-of-sight (LOS) availability analyses, and visualize the results. The developed programs are modular and can be applied for mission planning and viability analysis in a variety of Solar System applications. The tools can perform 2 and N-body orbit propagation, find inter-satellite and satellite to ground station LOS access (accounting for intermediate oblate spheroid body blocking, geometric restrictions of the antenna field-of-view (FOV), and relativistic corrections), and create animations of planetary movement, satellite orbits, and LOS accesses. The code is the basis for SCENICs broad analysis capabilities including dynamic link analysis, dilution-of-precision navigation analysis, and orbital availability calculations.

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

International Nuclear Information System (INIS)

Lee, M.; Kleban, S.; Clearwater, S.

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

Differentiation of orbital lymphoma and idiopathic orbital inflammatory pseudotumor: combined diagnostic value of conventional MRI and histogram analysis of ADC maps.

Science.gov (United States)

Ren, Jiliang; Yuan, Ying; Wu, Yingwei; Tao, Xiaofeng

2018-05-02

The overlap of morphological feature and mean ADC value restricted clinical application of MRI in the differential diagnosis of orbital lymphoma and idiopathic orbital inflammatory pseudotumor (IOIP). In this paper, we aimed to retrospectively evaluate the combined diagnostic value of conventional magnetic resonance imaging (MRI) and whole-tumor histogram analysis of apparent diffusion coefficient (ADC) maps in the differentiation of the two lesions. In total, 18 patients with orbital lymphoma and 22 patients with IOIP were included, who underwent both conventional MRI and diffusion weighted imaging before treatment. Conventional MRI features and histogram parameters derived from ADC maps, including mean ADC (ADC mean ), median ADC (ADC median ), skewness, kurtosis, 10th, 25th, 75th and 90th percentiles of ADC (ADC 10 , ADC 25 , ADC 75 , ADC 90 ) were evaluated and compared between orbital lymphoma and IOIP. Multivariate logistic regression analysis was used to identify the most valuable variables for discriminating. Differential model was built upon the selected variables and receiver operating characteristic (ROC) analysis was also performed to determine the differential ability of the model. Multivariate logistic regression showed ADC 10 (P = 0.023) and involvement of orbit preseptal space (P = 0.029) were the most promising indexes in the discrimination of orbital lymphoma and IOIP. The logistic model defined by ADC 10 and involvement of orbit preseptal space was built, which achieved an AUC of 0.939, with sensitivity of 77.30% and specificity of 94.40%. Conventional MRI feature of involvement of orbit preseptal space and ADC histogram parameter of ADC 10 are valuable in differential diagnosis of orbital lymphoma and IOIP.

Robustness analysis method for orbit control

Science.gov (United States)

Zhang, Jingrui; Yang, Keying; Qi, Rui; Zhao, Shuge; Li, Yanyan

2017-08-01

Satellite orbits require periodical maintenance due to the presence of perturbations. However, random errors caused by inaccurate orbit determination and thrust implementation may lead to failure of the orbit control strategy. Therefore, it is necessary to analyze the robustness of the orbit control methods. Feasible strategies which are tolerant to errors of a certain magnitude can be developed to perform reliable orbit control for the satellite. In this paper, first, the orbital dynamic model is formulated by Gauss' form of the planetary equation using the mean orbit elements; the atmospheric drag and the Earth's non-spherical perturbations are taken into consideration in this model. Second, an impulsive control strategy employing the differential correction algorithm is developed to maintain the satellite trajectory parameters in given ranges. Finally, the robustness of the impulsive control method is analyzed through Monte Carlo simulations while taking orbit determination error and thrust error into account.

Small-Body Extensions for the Satellite Orbit Analysis Program (SOAP)

Science.gov (United States)

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

Electric propulsion reliability: Statistical analysis of on-orbit anomalies and comparative analysis of electric versus chemical propulsion failure rates

Science.gov (United States)

Saleh, Joseph Homer; Geng, Fan; Ku, Michelle; Walker, Mitchell L. R.

2017-10-01

With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP's on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP's track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP's failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability- and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between January 1997 and December 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates. The important findings in this work include the following: (1) Post-2005, EP's reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both

Attitude control analysis of tethered de-orbiting

Science.gov (United States)

Peters, T. V.; Briz Valero, José Francisco; Escorial Olmos, Diego; Lappas, V.; Jakowski, P.; Gray, I.; Tsourdos, A.; Schaub, H.; Biesbroek, R.

2018-05-01

The increase of satellites and rocket upper stages in low earth orbit (LEO) has also increased substantially the danger of collisions in space. Studies have shown that the problem will continue to grow unless a number of debris are removed every year. A typical active debris removal (ADR) mission scenario includes launching an active spacecraft (chaser) which will rendezvous with the inactive target (debris), capture the debris and eventually deorbit both satellites. Many concepts for the capture of the debris while keeping a connection via a tether, between the target and chaser have been investigated, including harpoons, nets, grapples and robotic arms. The paper provides an analysis on the attitude control behaviour for a tethered de-orbiting mission based on the ESA e.Deorbit reference mission, where Envisat is the debris target to be captured by a chaser using a net which is connected to the chaser with a tether. The paper provides novel insight on the feasibility of tethered de-orbiting for the various mission phases such as stabilization after capture, de-orbit burn (plus stabilization), stabilization during atmospheric pass, highlighting the importance of various critical mission parameters such as the tether material. It is shown that the selection of the appropriate tether material while using simple controllers can reduce the effort needed for tethered deorbiting and can safely control the attitude of the debris/chaser connected with a tether, without the danger of a collision.

Numerical orbit generators of artificial earth satellites

Science.gov (United States)

Kugar, H. K.; Dasilva, W. C. C.

1984-04-01

A numerical orbit integrator containing updatings and improvements relative to the previous ones that are being utilized by the Departmento de Mecanica Espacial e Controle (DMC), of INPE, besides incorporating newer modellings resulting from the skill acquired along the time is presented. Flexibility and modularity were taken into account in order to allow future extensions and modifications. Characteristics of numerical accuracy, processing quickness, memory saving as well as utilization aspects were also considered. User's handbook, whole program listing and qualitative analysis of accuracy, processing time and orbit perturbation effects were included as well.

Operations analysis (study 2.1). Program SEPSIM (solar electric propulsion stage simulation). [in FORTRAN: space tug

Science.gov (United States)

Lang, T. J.

1974-01-01

Program SEPSIM is a FORTRAN program which performs deployment, servicing, and retrieval missions to synchronous equatorial orbit using a space tug with a continuous low thrust upper stage known as a solar electric propulsion stage (SEPS). The SEPS ferries payloads back and forth between an intermediate orbit and synchronous orbit, and performs the necessary servicing maneuvers in synchronous orbit. The tug carries payloads between the orbiter and the intermediate orbit, deploys fully fueled SEPS vehicles, and retrieves exhausted SEPS vehicles when, and if, required. The program is presently contained in subroutine form in the Logistical On-orbit VEhicle Servicing (LOVES) Program, but can also be run independently with the addition of a simple driver program.

Exploratory orbit analysis

International Nuclear Information System (INIS)

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

Exploratory orbit analysis

Energy Technology Data Exchange (ETDEWEB)

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.

A Preliminary Formation Flying Orbit Dynamics Analysis for Leonardo-BRDF

Science.gov (United States)

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.

Ground Contact Analysis for Korea’s Fictitious Lunar Orbiter Mission

Directory of Open Access Journals (Sweden)

Young-Joo Song

2013-12-01

Full Text Available In this research, the ground contact opportunity for the fictitious low lunar orbiter is analyzed to prepare for a future Korean lunar orbiter mission. The ground contact opportunity is basically derived from geometrical relations between the typical ground stations at the Earth, the relative positions of the Earth and Moon, and finally, the lunar orbiter itself. Both the cut-off angle and the orbiter’s Line of Sight (LOS conditions (weather orbiter is located at near or far side of the Moon seen from the Earth are considered to determine the ground contact opportunities. Four KOMPSAT Ground Stations (KGSs are assumed to be Korea’s future Near Earth Networks (NENs to support lunar missions, and world-wide separated Deep Space Networks (DSNs are also included during the contact availability analysis. As a result, it is concluded that about 138 times of contact will be made between the orbiter and the Daejeon station during 27.3 days of prediction time span. If these contact times are converted into contact duration, the duration is found to be about 8.55 days, about 31.31% of 27.3 days. It is discovered that selected four KGSs cannot provide continuous tracking of the lunar orbiter, meaning that international collaboration is necessary to track Korea’s future lunar orbiter effectively. Possible combinations of world-wide separated DSNs are also suggested to compensate for the lack of contact availability with only four KGSs, as with primary and backup station concepts. The provided algorithm can be easily modified to support any type of orbit around the Moon, and therefore, the presented results could aid further progress in the design field of Korea’s lunar orbiter missions.

Closed orbit analysis for RHIC

International Nuclear Information System (INIS)

Milutinovic, J.; Ruggiero, A.G.

1989-01-01

We examine the effects of four types of errors in the RHIC dipoles and quadrupoles on the on-momentum closed orbit in the machine. We use PATRIS both to handle statistically the effects of kick-modeled errors and to check the performance of the Fermilab correcting scheme in a framework of a more realistic modeling. On the basis of the accepted rms values of the lattice errors, we conclude that in about 40% of all studied cases the lattice must be to some extent pre-corrected in the framework of the so-called ''first turn around strategy,'' in order to get a closed orbit within the aperture limitations at all and, furthermore, for approximately 2/3 of the remaining cases we find that a single pass algorithm of the Fermilab scheme is not sufficient to bring closed orbit distortions down to acceptable levels. We have modified the scheme and have allowed repeated applications of the otherwise unchanged three bump method and in doing so we have been able to correct the orbit in a satisfactory manner. 4 refs., 2 figs., 3 tabs

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

Directory of Open Access Journals (Sweden)

Young-Rok Kim

2015-09-01

Full Text Available 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.

An advanced analysis method of initial orbit determination with too short arc data

Science.gov (United States)

Li, Binzhe; Fang, Li

2018-02-01

This paper studies the initial orbit determination (IOD) based on space-based angle measurement. Commonly, these space-based observations have short durations. As a result, classical initial orbit determination algorithms give poor results, such as Laplace methods and Gauss methods. In this paper, an advanced analysis method of initial orbit determination is developed for space-based observations. The admissible region and triangulation are introduced in the method. Genetic algorithm is also used for adding some constraints of parameters. Simulation results show that the algorithm can successfully complete the initial orbit determination.

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

International Nuclear Information System (INIS)

Gonçalves, L D; Rocco, E M; De Moraes, R V

2015-01-01

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. (paper)

ORBIT-3.0 - a computer code for simulation and correction of the closed orbit and first turn in synchrotrons

International Nuclear Information System (INIS)

Dinev, D.

1999-01-01

A new computer program ORBIT-3.0 for simulation and correction of the closed orbit and first turn in synchrotrons is described. The program works under WINDOWS 95/98/NT and is a full object of oriented applications. It has an interactive interface, enhanced graphical capabilities and on-line printing. The original algorithms DINAM - for closed orbit correction and FTURN - for first turn steering are described as well

WetLab-2: Tools for Conducting On-Orbit Quantitative Real-Time Gene Expression Analysis on ISS

Science.gov (United States)

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

Optimal selection of Orbital Replacement Unit on-orbit spares - A Space Station system availability model

Science.gov (United States)

Schwaab, Douglas G.

1991-01-01

A mathematical programing model is presented to optimize the selection of Orbital Replacement Unit on-orbit spares for the Space Station. The model maximizes system availability under the constraints of logistics resupply-cargo weight and volume allocations.

GLONASS orbit/clock combination in VNIIFTRI

Science.gov (United States)

Bezmenov, I.; Pasynok, S.

2015-08-01

An algorithm and a program for GLONASS satellites orbit/clock combination based on daily precise orbits submitted by several Analytic Centers were developed. Some theoretical estimates for combine orbit positions RMS were derived. It was shown that under condition that RMS of satellite orbits provided by the Analytic Centers during a long time interval are commensurable the RMS of combine orbit positions is no greater than RMS of other satellite positions estimated by any of the Analytic Centers.

AN IMPROVED DISTANCE AND MASS ESTIMATE FOR SGR A* FROM A MULTISTAR ORBIT ANALYSIS

Energy Technology Data Exchange (ETDEWEB)

Boehle, A.; Ghez, A. M.; Meyer, L.; Yelda, S.; Albers, S.; Martinez, G. D.; Becklin, E. E.; Do, T.; Morris, M. R.; Sitarski, B.; Witzel, G. [UCLA, Department of Physics and Astronomy, Los Angeles, CA 90095 (United States); Schödel, R. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía S/N, E-18008 Granada (Spain); Lu, J. R. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Matthews, K., E-mail: aboehle@astro.ucla.edu [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, MC 301-17, Pasadena, CA 91125 (United States)

2016-10-10

We present new, more precise measurements of the mass and distance of our Galaxy’s central supermassive black hole, Sgr A*. These results stem from a new analysis that more than doubles the time baseline for astrometry of faint stars orbiting Sgr A*, combining 2 decades of speckle imaging and adaptive optics data. Specifically, we improve our analysis of the speckle images by using information about a star’s orbit from the deep adaptive optics data (2005–2013) to inform the search for the star in the speckle years (1995–2005). When this new analysis technique is combined with the first complete re-reduction of Keck Galactic Center speckle images using speckle holography, we are able to track the short-period star S0-38 ( K -band magnitude = 17, orbital period = 19 yr) through the speckle years. We use the kinematic measurements from speckle holography and adaptive optics to estimate the orbits of S0-38 and S0-2 and thereby improve our constraints of the mass ( M {sub bh}) and distance ( R {sub o} ) of Sgr A*: M {sub bh} = (4.02 ± 0.16 ± 0.04) × 10{sup 6} M {sub ⊙} and 7.86 ± 0.14 ± 0.04 kpc. The uncertainties in M {sub bh} and R {sub o} as determined by the combined orbital fit of S0-2 and S0-38 are improved by a factor of 2 and 2.5, respectively, compared to an orbital fit of S0-2 alone and a factor of ∼2.5 compared to previous results from stellar orbits. This analysis also limits the extended dark mass within 0.01 pc to less than 0.13 × 10{sup 6} M {sub ⊙} at 99.7% confidence, a factor of 3 lower compared to prior work.

Distant retrograde orbits and the asteroid hazard

Science.gov (United States)

Perozzi, Ettore; Ceccaroni, Marta; Valsecchi, Giovanni B.; Rossi, Alessandro

2017-08-01

Distant Retrograde Orbits (DROs) gained a novel wave of fame in space mission design because of their numerous advantages within the framework of the US plans for bringing a large asteroid sample in the vicinity of the Earth as the next target for human exploration. DROs are stable solutions of the three-body problem that can be used whenever an object, whether of natural or artificial nature, is required to remain in the neighborhood of a celestial body without being gravitationally captured by it. As such, they represent an alternative option to Halo orbits around the collinear Lagrangian points L1 and L2. Also known under other names ( e.g., quasi-satellite orbits, cis-lunar orbits, family- f orbits) these orbital configurations found interesting applications in several mission profiles, like that of a spacecraft orbiting around the small irregularly shaped satellite of Mars Phobos or the large Jovian moon Europa. In this paper a basic explanation of the DRO dynamics is presented in order to clarify some geometrical properties that characterize them. Their accessibility is then discussed from the point of view of mission analysis under different assumptions. Finally, their relevance within the framework of the present asteroid hazard protection programs is shown, stressing the significant increase in warning time they would provide in the prediction of impactors coming from the direction of the Sun.

Independent Orbiter Assessment (IOA): FMEA/CIL assessment

Science.gov (United States)

Hinsdale, L. W.; Swain, L. J.; Barnes, J. E.

1988-01-01

The McDonnell Douglas Astronautics Company (MDAC) was selected to perform an Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL). Direction was given by the Orbiter and GFE Projects Office to perform the hardware analysis and assessment using the instructions and ground rules defined in NSTS 22206. The IOA analysis featured a top-down approach to determine hardware failure modes, criticality, and potential critical items. To preserve independence, the analysis was accomplished without reliance upon the results contained within the NASA and Prime Contractor FMEA/CIL documentation. The assessment process compared the independently derived failure modes and criticality assignments to the proposed NASA post 51-L FMEA/CIL documentation. When possible, assessment issues were discussed and resolved with the NASA subsystem managers. Unresolved issues were elevated to the Orbiter and GFE Projects Office manager, Configuration Control Board (CCB), or Program Requirements Control Board (PRCB) for further resolution. The most important Orbiter assessment finding was the previously unknown stuck autopilot push-button criticality 1/1 failure mode. The worst case effect could cause loss of crew/vehicle when the microwave landing system is not active. It is concluded that NASA and Prime Contractor Post 51-L FMEA/CIL documentation assessed by IOA is believed to be technically accurate and complete. All CIL issues were resolved. No FMEA issues remain that have safety implications. Consideration should be given, however, to upgrading NSTS 22206 with definitive ground rules which more clearly spell out the limits of redundancy.

JSC Orbital Debris Website Description

Science.gov (United States)

Johnson, Nicholas L.

2006-01-01

Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as

Planetary Protection Bioburden Analysis Program

Science.gov (United States)

Beaudet, Robert A.

2013-01-01

This program is a Microsoft Access program that performed statistical analysis of the colony counts from assays performed on the Mars Science Laboratory (MSL) spacecraft to determine the bioburden density, 3-sigma biodensity, and the total bioburdens required for the MSL prelaunch reports. It also contains numerous tools that report the data in various ways to simplify the reports required. The program performs all the calculations directly in the MS Access program. Prior to this development, the data was exported to large Excel files that had to be cut and pasted to provide the desired results. The program contains a main menu and a number of submenus. Analyses can be performed by using either all the assays, or only the accountable assays that will be used in the final analysis. There are three options on the first menu: either calculate using (1) the old MER (Mars Exploration Rover) statistics, (2) the MSL statistics for all the assays, or 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

An analysis of the orbital distribution of solid rocket motor slag

Science.gov (United States)

Horstman, Matthew F.; Mulrooney, Mark

2009-01-01

The contribution by solid rocket motors (SRMs) to the orbital debris environment is potentially significant and insufficiently studied. Design and combustion processes can lead to the emission of enough by-products to warrant assessment of their contribution to orbital debris. These particles are formed during SRM tail-off, or burn termination, by the rapid solidification of molten Al2O3 slag accumulated during the burn. The propensity of SRMs to generate particles larger than 100μm raises concerns regarding the debris environment. Sizes as large as 1 cm have been witnessed in ground tests, and comparable sizes have been estimated via observations of sub-orbital tail-off events. Utilizing previous research we have developed more sophisticated size distributions and modeled the time evolution of resultant orbital populations using a historical database of SRM launches, propellant, and likely location and time of tail-off. This analysis indicates that SRM ejecta is a significant component of the debris environment.

An analysis of near-circular lunar mapping orbits

Indian Academy of Sciences (India)

Numerical investigations have been carried out to analyse the evolution of lunar circular orbits and the influence of the higher order harmonics of the lunar gravity field. The aim is to select the appropriate near-circular orbit characteristics, which extend orbit life through passive orbit maintenance. The spherical harmonic ...

Analysis of the Accuracy of Beidou Combined Orbit Determination Enhanced by LEO and ISL

Directory of Open Access Journals (Sweden)

FENG Laiping

2017-05-01

Full Text Available In order to improve the precision of BeiDou orbit determination under the conditions of regional ground monitoring station and make good use of increasingly rich on-board data and upcoming ISL technology, a method of BeiDou precision orbit determination is proposed which combines the use of ground monitoring stations data, low earth orbit satellite(LEOs data and Inter-Satellite Link(ISL data. The effects of assisting data of LEOs and ISL on the precision orbit determination of navigation satellite are discussed. Simulation analysis is carried out mainly from the number of LEOs, orbit slot configuration and ISL. The results show that the orbit precision of BeiDou will greatly improve about 73% with a small number of LEOs, while improvement of clock bias is not remarkable; the uniform orbit slot configuration of the same number of LEOs has a modest effect on the accuracy of combined orbit determination; compared with LEOs, the increase of ISL will significantly improve the accuracy of orbit determination with a higher efficiency.

Orbit analysis

International Nuclear Information System (INIS)

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

Orbit analysis

Energy Technology Data Exchange (ETDEWEB)

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.

Failure analysis of satellite subsystems to define suitable de-orbit devices

Science.gov (United States)

Palla, Chiara; Peroni, Moreno; Kingston, Jennifer

2016-11-01

Space missions in Low Earth Orbit (LEO) are severely affected by the build-up of orbital debris. A key practice, to be compliant with IADC (Inter-Agency Space Debris Coordination Committee) mitigation guidelines, is the removal of space systems that interfere with the LEO region not later than 25 years after the End of Mission. It is important to note that the current guidelines are not generally legally binding, even if different Space Agencies are now looking at the compliance for their missions. If the guidelines will change in law, it will be mandatory to have a postmission disposal strategy for all satellites, including micro and smaller classes. A potential increased number of these satellites is confirmed by different projections, in particular in the commercial sector. Micro and smaller spacecraft are, in general, not provided with propulsion capabilities to achieve a controlled re-entry, so they need different de-orbit disposal methods. When considering the utility of different debris mitigation methods, it is useful to understand which spacecraft subsystems are most likely to fail and how this may affect the operation of a de-orbit system. This also helps the consideration of which components are the most relevant or should be redundant depending on the satellite mass class. This work is based on a sample of LEO and MEO satellites launched between January 2000 and December 2014 with mass lower than 1000 kg. Failure analysis of satellite subsystems is performed by means of the Kaplan-Meier survival analysis; the parametric fits are conducted with Weibull distributions. The study is carried out by using the satellite database SpaceTrak™ which provides anomalies, failures, and trends information for spacecraft subsystems and launch vehicles. The database identifies five states for each satellite subsystem: three degraded states, one fully operational state, and one failed state (complete failure). The results obtained can guide the identification of the

Generating Animated Displays of Spacecraft Orbits

Science.gov (United States)

Candey, Robert M.; Chimiak, Reine A.; Harris, Bernard T.

2005-01-01

Tool for Interactive Plotting, Sonification, and 3D Orbit Display (TIPSOD) is a computer program for generating interactive, animated, four-dimensional (space and time) displays of spacecraft orbits. TIPSOD utilizes the programming interface of the Satellite Situation Center Web (SSCWeb) services to communicate with the SSC logic and database by use of the open protocols of the Internet. TIPSOD is implemented in Java 3D and effects an extension of the preexisting SSCWeb two-dimensional static graphical displays of orbits. Orbits can be displayed in any or all of the following seven reference systems: true-of-date (an inertial system), J2000 (another inertial system), geographic, geomagnetic, geocentric solar ecliptic, geocentric solar magnetospheric, and solar magnetic. In addition to orbits, TIPSOD computes and displays Sibeck's magnetopause and Fairfield's bow-shock surfaces. TIPSOD can be used by the scientific community as a means of projection or interpretation. It also has potential as an educational tool.

Scout: orbit analysis and hazard assessment for NEOCP objects

Science.gov (United States)

Farnocchia, Davide; Chesley, Steven R.; Chamberlin, Alan B.

2016-10-01

It typically takes a few days for a newly discovered asteroid to be officially recognized as a real object. During this time, the tentative discovery is published on the Minor Planet Center's Near-Earth Object Confirmation Page (NEOCP) until additional observations confirm that the object is a real asteroid rather than an observational artifact or an artificial object. Also, NEOCP objects could have a limited observability window and yet be scientifically interesting, e.g., radar and lightcurve targets, mini-moons (temporary Earth captures), mission accessible targets, close approachers or even impactors. For instance, the only two asteroids discovered before an impact, 2008 TC3 and 2014 AA, both reached the Earth less than a day after discovery. For these reasons we developed Scout, an automated system that provides an orbital and hazard assessment for NEOCP objects within minutes after the observations are available. Scout's rapid analysis increases the chances of securing the trajectory of interesting NEOCP objects before the ephemeris uncertainty grows too large or the observing geometry becomes unfavorable. The generally short observation arcs, perhaps only a few hours or even less, lead severe degeneracies in the orbit estimation process. To overcome these degeneracies Scout relies on systematic ranging, a technique that derives possible orbits by scanning a grid in 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 derive a distribution of the possible orbits and in turn identify the NEOCP objects of most interest to prioritize followup efforts. In particular, Scout ranks objects according to the likelihood of an impact, estimates the close approach distance, the Earth-relative minimum orbit intersection distance and v-infinity, and computes scores to identify objects more likely to be an NEO, a km-sized NEO, a Potentially

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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

2010-01-01

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 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 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.

Analysis of Errors in a Special Perturbations Satellite Orbit Propagator

Energy Technology Data Exchange (ETDEWEB)

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.

The O/OREOS Mission - Astrobiology in Low Earth Orbit. [Astrobiology in Low Earth Orbit

Science.gov (United States)

Ehrenfreund, P.; Ricco, A. J.; Squires, D.; Kitts, C.; Agasid, E.; Bramall, N.; Bryson, K.; Chittenden, J.; Conley, C.; Cook, A.;

Communication: Localized molecular orbital analysis of the effect of electron correlation on the anomalous isotope effect in the NMR spin-spin coupling constant in methane

Energy Technology Data Exchange (ETDEWEB)

Zarycz, M. Natalia C., E-mail: mnzarycz@gmail.com; Provasi, Patricio F., E-mail: patricio@unne.edu.ar [Department of Physics, University of Northeastern - CONICET, Av. Libertad 5500, Corrientes W3404AAS (Argentina); Sauer, Stephan P. A., E-mail: sauer@kiku.dk [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark)

2014-10-21

We discuss the effect of electron correlation on the unexpected differential sensitivity (UDS) in the {sup 1}J(C–H) coupling constant of CH{sub 4} using a decomposition into contributions from localized molecular orbitals and compare with the {sup 1}J(N–H) coupling constant in NH{sub 3}. In particular, we discuss the well known fact that uncorrelated coupled Hartree-Fock (CHF) calculations are not able to reproduce the UDS in methane. For this purpose we have implemented for the first time a localized molecular orbital analysis for the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes—SOPPA(CCSD) in the DALTON program. Comparing the changes in the localized orbital contributions at the correlated SOPPA and SOPPA(CCSD) levels and at the uncorrelated CHF level, we find that the latter overestimates the effect of stretching the bond between the coupled atoms on the contribution to the coupling from the localized bonding orbital between these atoms. This disturbs the subtle balance between the molecular orbital contributions, which lead to the UDS in methane.

NASA's New Orbital Debris Engineering Model, ORDEM2010

Science.gov (United States)

Krisko, Paula H.

2010-01-01

This paper describes the functionality and use of ORDEM2010, which replaces ORDEM2000, as the NASA Orbital Debris Program Office (ODPO) debris engineering model. Like its predecessor, ORDEM2010 serves the ODPO mission of providing spacecraft designers/operators and debris observers with a publicly available model to calculate orbital debris flux by current-state-of-knowledge methods. The key advance in ORDEM2010 is the input file structure of the yearly debris populations from 1995-2035 of sizes 10 micron - 1 m. These files include debris from low-Earth orbits (LEO) through geosynchronous orbits (GEO). Stable orbital elements (i.e., those that do not randomize on a sub-year timescale) are included in the files as are debris size, debris number, material density, random error and population error. Material density is implemented from ground-test data into the NASA breakup model and assigned to debris fragments accordingly. The random and population errors are due to machine error and uncertainties in debris sizes. These high-fidelity population files call for a much higher-level model analysis than what was possible with the populations of ORDEM2000. Population analysis in the ORDEM2010 model consists of mapping matrices that convert the debris population elements to debris fluxes. One output mode results in a spacecraft encompassing 3-D igloo of debris flux, compartmentalized by debris size, velocity, pitch, and yaw with respect to spacecraft ram direction. The second output mode provides debris flux through an Earth-based telescope/radar beam from LEO through GEO. This paper compares the new ORDEM2010 with ORDEM2000 in terms of processes and results with examples of specific orbits.

Mission Analysis and Orbit Control of Interferometric Wheel Formation Flying

Science.gov (United States)

Fourcade, J.

Flying satellite in formation requires maintaining the specific relative geometry of the spacecraft with high precision. This requirement raises new problem of orbit control. This paper presents the results of the mission analysis of a low Earth observation system, the interferometric wheel, patented by CNES. This wheel is made up of three receiving spacecraft, which follow an emitting Earth observation radar satellite. The first part of this paper presents trades off which were performed to choose orbital elements of the formation flying which fulfils all constraints. The second part presents orbit positioning strategies including reconfiguration of the wheel to change its size. The last part describes the station keeping of the formation. Two kinds of constraints are imposed by the interferometric system : a constraint on the distance between the wheel and the radar satellite, and constraints on the distance between the wheel satellites. The first constraint is fulfilled with a classical chemical station keeping strategy. The second one is fulfilled using pure passive actuators. Due to the high stability of the relative eccentricity of the formation, only the relative semi major axis had to be controlled. Differential drag due to differential attitude motion was used to control relative altitude. An autonomous orbit controller was developed and tested. The final accuracy is a relative station keeping better than few meters for a wheel size of one kilometer.

Future earth orbit transportation systems/technology implications

Science.gov (United States)

Henry, B. Z.; Decker, J. P.

1976-01-01

Assuming Space Shuttle technology to be state-of-the-art, projected technological advances to improve the capabilities of single-stage-to-orbit (SSTO) derivatives are examined. An increase of about 30% in payload performance can be expected from upgrading the present Shuttle system through weight and drag reductions and improvements in the propellants and engines. The ODINEX (Optimal Design Integration Executive Computer Program) program has been used to explore design options. An advanced technology SSTO baseline system derived from ODINEX analysis has a conventional wing-body configuration using LOX/LH engines, three with two-position nozzles with expansion ratios of 40 and 200 and four with fixed nozzles with an expansion ratio of 40. Two assisted-takeoff approaches are under consideration in addition to a concept in which the orbital vehicle takes off empty using airbreathing propulsion and carries out a rendezvous with two large cryogenic tankers carrying propellant at an altitude of 6100 m. Further approaches under examination for propulsion, aerothermodynamic design, and design integration are described.

A Novel Double Cluster and Principal Component Analysis-Based Optimization Method for the Orbit Design of Earth Observation Satellites

Directory of Open Access Journals (Sweden)

Yunfeng Dong

2017-01-01

Full Text Available The weighted sum and genetic algorithm-based hybrid method (WSGA-based HM, which has been applied to multiobjective orbit optimizations, is negatively influenced by human factors through the artificial choice of the weight coefficients in weighted sum method and the slow convergence of GA. To address these two problems, a cluster and principal component analysis-based optimization method (CPC-based OM is proposed, in which many candidate orbits are gradually randomly generated until the optimal orbit is obtained using a data mining method, that is, cluster analysis based on principal components. Then, the second cluster analysis of the orbital elements is introduced into CPC-based OM to improve the convergence, developing a novel double cluster and principal component analysis-based optimization method (DCPC-based OM. In DCPC-based OM, the cluster analysis based on principal components has the advantage of reducing the human influences, and the cluster analysis based on six orbital elements can reduce the search space to effectively accelerate convergence. The test results from a multiobjective numerical benchmark function and the orbit design results of an Earth observation satellite show that DCPC-based OM converges more efficiently than WSGA-based HM. And DCPC-based OM, to some degree, reduces the influence of human factors presented in WSGA-based HM.

THE NASA-UC ETA-EARTH PROGRAM. I. A SUPER-EARTH ORBITING HD 7924

International Nuclear Information System (INIS)

Howard, Andrew W.; Marcy, Geoffrey W.; Johnson, John Asher; Fischer, Debra A.; Giguere, Matthew J.; Isaacson, Howard; Wright, Jason T.; Henry, Gregory W.; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E.

2009-01-01

We report the discovery of the first low-mass planet to emerge from the NASA-UC Eta-Earth Program, a super-Earth orbiting the K0 dwarf HD 7924. Keplerian modeling of precise Doppler radial velocities reveals a planet with minimum mass M P sin i = 9.26 M + in a P = 5.398 d orbit. Based on Keck-HIRES measurements from 2001 to 2008, the planet is robustly detected with an estimated false alarm probability of less than 0.001. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 7924 is photometrically constant over the radial velocity period to 0.19 mmag, supporting the existence of the planetary companion. No transits were detected down to a photometric limit of ∼0.5 mmag, eliminating transiting planets with a variety of compositions. HD 7924b is one of only eight planets detected by the radial velocity technique with M P sin i + and as such is a member of an emerging family of low-mass planets that together constrain theories of planet formation.

Identifying Lattice, Orbit, And BPM Errors in PEP-II

International Nuclear Information System (INIS)

Decker, F.-J.; SLAC

2005-01-01

The PEP-II B-Factory is delivering peak luminosities of up to 9.2 · 10 33 1/cm 2 · l/s. This is very impressive especially considering our poor understanding of the lattice, absolute orbit and beam position monitor system (BPM). A few simple MATLAB programs were written to get lattice information, like betatron functions in a coupled machine (four all together) and the two dispersions, from the current machine and compare it the design. Big orbit deviations in the Low Energy Ring (LER) could be explained not by bad BPMs (only 3), but by many strong correctors (one corrector to fix four BPMs on average). Additionally these programs helped to uncover a sign error in the third order correction of the BPM system. Further analysis of the current information of the BPMs (sum of all buttons) indicates that there might be still more problematic BPMs

Structural Health Monitoring Analysis for the Orbiter Wing Leading Edge

Science.gov (United States)

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.

Asteroid orbital error analysis: Theory and application

Science.gov (United States)

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).

Spatial analysis of galactic cosmic ray particles in low earth orbit/near equator orbit using SPENVIS

International Nuclear Information System (INIS)

Suparta, W; Zulkeple, S K

2014-01-01

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.

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

Energy Technology Data Exchange (ETDEWEB)

Ohwaki, Tsukuru [Advanced Materials Laboratory, Nissan Research Center, Nissan Motor Co., Ltd., 1 Natsushima-cho, Yokosuka, Kanagawa 237-8523 (Japan); Otani, Minoru [Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Ozaki, Taisuke [Research Center for Simulation Science (RCSS), Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

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})

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

International Nuclear Information System (INIS)

Ohwaki, Tsukuru; Otani, Minoru; Ozaki, Taisuke

2014-01-01

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 4 )

Analytic robust stability analysis of SVD orbit feedback

CERN Document Server

Pfingstner, Jürgen

2012-01-01

Orbit feedback controllers are indispensable for the operation of modern particle accelerators. Many such controllers are based on the decoupling of the inputs and outputs of the system to be controlled with the help of the singular value decomposition (SVD controller). It is crucial to verify the stability of SVD controllers, also in the presence of mismatches between the used accelerator model and the real machine (robust stability problem). In this paper, analytical criteria for guaranteed stability margins of SVD orbit feedback systems for three different types of model mismatches are presented: scaling errors of actuators and BPMs (beam position monitors) and additive errors of the orbit response matrix. For the derivation of these criteria, techniques from robust control theory have been used, e.g the small gain theorem. The obtained criteria can be easily applied directly to other SVD orbit feedback systems. As an example, the criteria were applied to the orbit feedback system of the Compact Linear ...

Orbit control on SPEAR: a progress report

International Nuclear Information System (INIS)

Corbett, W.J.; Keeley, D.

1994-01-01

In this paper, we report work on initial studies of the global feedback system for SPEAR. In particular, we describe components of a comprehensive accelerator simulation program used to assess the performance of harmonic and eigenvector orbit control algorithms. This program has also been used to choose new bpm sites, and can simulate the interaction between global and local orbit feedback systems. A prototype on-line version used for SPEAR is discussed. copyright 1994 American Institute of Physics

Methods of orbit correction system optimization

International Nuclear Information System (INIS)

Chao, Yu-Chiu.

1997-01-01

Extracting optimal performance out of an orbit correction system is an important component of accelerator design and evaluation. The question of effectiveness vs. economy, however, is not always easily tractable. This is especially true in cases where betatron function magnitude and phase advance do not have smooth or periodic dependencies on the physical distance. In this report a program is presented using linear algebraic techniques to address this problem. A systematic recipe is given, supported with quantitative criteria, for arriving at an orbit correction system design with the optimal balance between performance and economy. The orbit referred to in this context can be generalized to include angle, path length, orbit effects on the optical transfer matrix, and simultaneous effects on multiple pass orbits

Space shuttle orbit maneuvering engine reusable thrust chamber program

Science.gov (United States)

Senneff, J. M.

1975-01-01

Reusable thrust chamber and injector concepts were evaluated for the space shuttle orbit maneuvering engine (OME). Parametric engine calculations were carried out by computer program for N2O4/amine, LOX/amine and LOX/hydrocarbon propellant combinations for engines incorporating regenerative cooled and insulated columbium thrust chambers. The calculation methods are described including the fuel vortex film cooling method of combustion gas temperature control, and performance prediction. A method of acceptance of a regeneratively cooled heat rejection reduction using a silicone oil additive was also demonstrated by heated tube heat transfer testing. Regeneratively cooled thrust chamber operation was also demonstrated where the injector was characterized for the OME application with a channel wall regenerative thrust chamber. Bomb stability testing of the demonstration chambers/injectors demonstrated recovery for the nominal design of acoustic cavities. Cavity geometry changes were also evaluated to assess their damping margin. Performance and combustion stability was demonstrated of the originally developed 10 inch diameter combustion pattern operating in an 8 inch diameter thrust chamber.

Density functional theory, comparative vibrational spectroscopic studies, highest occupied molecular orbital and lowest unoccupied molecular orbital analysis of Linezolid

Science.gov (United States)

Rajalakshmi, K.; Gunasekaran, S.; Kumaresan, S.

2015-06-01

The Fourier transform infrared spectra and Fourier transform Raman spectra of Linezolid have been recorded in the regions 4,000-400 and 4,000-100 cm-1, respectively. Utilizing the observed Fourier transform infrared spectra and Fourier transform Raman spectra data, a complete vibrational assignment and analysis of the fundamental modes of the compound have been carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, have been calculated by density functional theory with 6-31G(d,p), 6-311G(d,p) and M06-2X/6-31G(d,p) levels. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of Linezolid is reported. Mulliken's net charges have also been calculated. Ultraviolet-visible spectrum of the title molecule has also been calculated using time-dependent density functional method. Besides, molecular electrostatic potential, highest occupied molecular orbital and lowest unoccupied molecular orbital analysis and several thermodynamic properties have been performed by the density functional theoretical method.

Modification of an impulse-factoring orbital transfer technique to account for orbit determination and maneuver execution errors

Science.gov (United States)

Kibler, J. F.; Green, R. N.; Young, G. R.; Kelly, M. G.

1974-01-01

A method has previously been developed to satisfy terminal rendezvous and intermediate timing constraints for planetary missions involving orbital operations. The method uses impulse factoring in which a two-impulse transfer is divided into three or four impulses which add one or two intermediate orbits. The periods of the intermediate orbits and the number of revolutions in each orbit are varied to satisfy timing constraints. Techniques are developed to retarget the orbital transfer in the presence of orbit-determination and maneuver-execution errors. Sample results indicate that the nominal transfer can be retargeted with little change in either the magnitude (Delta V) or location of the individual impulses. Additonally, the total Delta V required for the retargeted transfer is little different from that required for the nominal transfer. A digital computer program developed to implement the techniques is described.

GOC: General Orbit Code

International Nuclear Information System (INIS)

Maddox, L.B.; McNeilly, G.S.

1979-08-01

GOC (General Orbit Code) is a versatile program which will perform a variety of calculations relevant to isochronous cyclotron design studies. In addition to the usual calculations of interest (e.g., equilibrium and accelerated orbits, focusing frequencies, field isochronization, etc.), GOC has a number of options to calculate injections with a charge change. GOC provides both printed and plotted output, and will follow groups of particles to allow determination of finite-beam properties. An interactive PDP-10 program called GIP, which prepares input data for GOC, is available. GIP is a very easy and convenient way to prepare complicated input data for GOC. Enclosed with this report are several microfiche containing source listings of GOC and other related routines and the printed output from a multiple-option GOC run

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

Science.gov (United States)

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.

Orbital express capture system: concept to reality

Science.gov (United States)

Stamm, Shane; Motaghedi, Pejmun

2004-08-01

The development of autonomous servicing of on-orbit spacecraft has been a sought after objective for many years. A critical component of on-orbit servicing involves the ability to successfully capture, institute mate, and perform electrical and fluid transfers autonomously. As part of a Small Business Innovation Research (SBIR) grant, Starsys Research Corporation (SRC) began developing such a system. Phase I of the grant started in 1999, with initial work focusing on simultaneously defining the parameters associated with successful docking while designing to those parameters. Despite the challenge of working without specific requirements, SRC completed development of a prototype design in 2000. Throughout the following year, testing was conducted on the prototype to characterize its performance. Having successfully completed work on the prototype, SRC began a Phase II SBIR effort in mid-2001. The focus of the second phase was a commercialization effort designed to augment the prototype model into a more flight-like design. The technical requirements, however, still needed clear definition for the design to progress. The advent of the Orbital Express (OE) program provided much of that definition. While still in the proposal stages of the OE program, SRC began tailoring prototype redesign efforts to the OE program requirements. A primary challenge involved striking a balance between addressing the technical requirements of OE while designing within the scope of the SBIR. Upon award of the OE contract, the Phase II SBIR design has been fully developed. This new design, designated the Mechanical Docking System (MDS), successfully incorporated many of the requirements of the OE program. SRC is now completing dynamic testing on the MDS hardware, with a parallel effort of developing a flight design for OE. As testing on the MDS progresses, the design path that was once common to both SBIR effort and the OE program begins to diverge. The MDS will complete the scope of the

A comprehensive analysis of molecule-intrinsic quasi-atomic, bonding, and correlating orbitals. I. Hartree-Fock wave functions

International Nuclear Information System (INIS)

West, Aaron C.; Schmidt, Michael W.; Gordon, Mark S.; Ruedenberg, Klaus

2013-01-01

Through a basis-set-independent web of localizing orbital-transformations, the electronic wave function of a molecule is expressed in terms of a set of orbitals that reveal the atomic structure and the bonding pattern of a molecule. The analysis is based on resolving the valence orbital space in terms of an internal space, which has minimal basis set dimensions, and an external space. In the internal space, oriented quasi-atomic orbitals and split-localized molecular orbitals are determined by new, fast localization methods. The density matrix between the oriented quasi-atomic orbitals as well as the locations of the split-localized orbitals exhibit atomic populations and inter-atomic bonding patterns. A correlation-adapted quasi-atomic basis is determined in the external orbital space. The general formulations are specified in detail for Hartree-Fock wave functions. Applications to specific molecules exemplify the general scheme

Orbiter LH2 Feedline Flowliner Cracking Problem. Version 1.0

Science.gov (United States)

Harris, Charles E.; Cragg, Clinton H.; Raju, Ivatury S.; Elliot, Kenny B.; Madaras, Eric I.; Piascik, Robert S.; Halford, Gary R.; Bonacuse, Peter J.; Sutliff, Daniel L.; Bakhle, Milind A.

2005-01-01

In May of 2002, three cracks were found in the downstream flowliner at the gimbal joint in the LH2 feedline at the interface with the Low Pressure Fuel Turbopump (LPFP) of Space Shuttle Main Engine (SSME) #1 of Orbiter OV-104. Subsequent inspections of the feedline flowliners in the other orbiters revealed the existence of 8 additional cracks. No cracks were found in the LO2 feedline flowliners. A solution to the cracking problem was developed and implemented on all orbiters. The solution included weld repair of all detectable cracks and the polishing of all slot edges to remove manufacturing discrepancies that could initiate new cracks. Using the results of a fracture mechanics analysis with a scatter factor of 4 on the predicted fatigue life, the orbiters were cleared for return to flight with a one-flight rationale requiring inspections after each flight. OV-104 flew mission STS-112 and OV-105 flew mission STS-113. The post-flight inspections did not find any cracks in the repaired flowliners. At the request of the Orbiter Program, the NESC conducted an assessment of the Orbiter LH2 Feedline Flowliner cracking problem with a team of subject matter experts from throughout NASA.

Thermal stresses in the space shuttle orbiter: Analysis versus test

International Nuclear Information System (INIS)

Grooms, H.R.; Gibson, W.F. Jr.; Benson, P.L.

1984-01-01

Significant temperature differences occur between the internal structure and the outer skin of the Space Shuttle Orbiter as it returns from space. These temperature differences cause important thermal stresses. A finite element model containing thousands of degrees of freedom is used to predict these stresses. A ground test was performed to verify the prediction method. The analysis and test results compare favorably. (orig.)

Independent Orbiter Assessment (IOA): Assessment of the orbital maneuvering system FMEA/CIL, volume 1

Science.gov (United States)

Prust, Chet D.; Haufler, W. A.; Marino, A. J.

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 effort first completed an analysis of the Orbital Maneuvering System (OMS) hardware and Electrical Power Distribution and Control (EPD and C), generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the proposed Post 51-L NASA FMEA/CIL baseline. This report documents the results of that comparison for the Orbiter OMS hardware. The IOA analysis defined the OMS as being comprised of the following subsystems: helium pressurization, propellant storage and distribution, Orbital Maneuvering Engine, and EPD and C. The IOA product for the OMS analysis consisted of 284 hardware and 667 EPD and C failure mode worksheets that resulted in 160 hardware and 216 EPD and C potential critical items (PCIs) being identified. A comparison was made of the IOA product to the NASA FMEA/CIL baseline which consisted of 101 hardware and 142 EPD and C CIL items.

Researches on the Orbit Determination and Positioning of the Chinese Lunar Exploration Program

Science.gov (United States)

Li, P. J.

2015-07-01

This dissertation studies the precise orbit determination (POD) and positioning of the Chinese lunar exploration spacecraft, emphasizing the variety of VLBI (very long baseline interferometry) technologies applied for the deep-space exploration, and their contributions to the methods and accuracies of the precise orbit determination and positioning. In summary, the main contents are as following: In this work, using the real-time data measured by the CE-2 (Chang'E-2) detector, the accuracy of orbit determination is analyzed for the domestic lunar probe under the present condition, and the role played by the VLBI tracking data is particularly reassessed through the precision orbit determination experiments for CE-2. The experiments of the short-arc orbit determination for the lunar probe show that the combination of the ranging and VLBI data with the arc of 15 minutes is able to improve the accuracy by 1-1.5 order of magnitude, compared to the cases for only using the ranging data with the arc of 3 hours. The orbital accuracy is assessed through the orbital overlapping analysis, and the results show that the VLBI data is able to contribute to the CE-2's long-arc POD especially in the along-track and orbital normal directions. For the CE-2's 100 km× 100 km lunar orbit, the position errors are better than 30 meters, and for the CE-2's 15 km× 100 km orbit, the position errors are better than 45 meters. The observational data with the delta differential one-way ranging (Δ DOR) from the CE-2's X-band monitoring and control system experimental are analyzed. It is concluded that the accuracy of Δ DOR delay is dramatically improved with the noise level better than 0.1 ns, and the systematic errors are well calibrated. Although it is unable to support the development of an independent lunar gravity model, the tracking data of CE-2 provided the evaluations of different lunar gravity models through POD, and the accuracies are examined in terms of orbit-to-orbit solution

Single-stage-to-orbit versus two-stage-two-orbit: A cost perspective

Science.gov (United States)

Hamaker, Joseph W.

1996-03-01

This paper considers the possible life-cycle costs of single-stage-to-orbit (SSTO) and two-stage-to-orbit (TSTO) reusable launch vehicles (RLV's). The analysis parametrically addresses the issue such that the preferred economic choice comes down to the relative complexity of the TSTO compared to the SSTO. The analysis defines the boundary complexity conditions at which the two configurations have equal life-cycle costs, and finally, makes a case for the economic preference of SSTO over TSTO.

CASTOR: Cathode/Anode Satellite Thruster for Orbital Repositioning

Science.gov (United States)

Mruphy, Gloria A.

2010-01-01

The purpose of CASTOR (Cathode/Anode Satellite Thruster for Orbital Repositioning) satellite is to demonstrate in Low Earth Orbit (LEO) a nanosatellite that uses a Divergent Cusped Field Thruster (DCFT) to perform orbital maneuvers representative of an orbital transfer vehicle. Powered by semi-deployable solar arrays generating 165W of power, CASTOR will achieve nearly 1 km/s of velocity increment over one year. As a technology demonstration mission, success of CASTOR in LEO will pave the way for a low cost, high delta-V orbital transfer capability for small military and civilian payloads in support of Air Force and NASA missions. The educational objective is to engage graduate and undergraduate students in critical roles in the design, development, test, carrier integration and on-orbit operations of CASTOR as a supplement to their curricular activities. This program is laying the foundation for a long-term satellite construction program at MIT. The satellite is being designed as a part of AFRL's University Nanosatellite Program, which provides the funding and a framework in which student satellite teams compete for a launch to orbit. To this end, the satellite must fit within an envelope of 50cmx50cmx60cm, have a mass of less than 50kg, and meet stringent structural and other requirements. In this framework, the CASTOR team successfully completed PDR in August 2009 and CDR in April 2010 and will compete at FCR (Flight Competition Review) in January 2011. The complexity of the project requires implementation of many systems engineering techniques which allow for development of CASTOR from conception through FCR and encompass the full design, fabrication, and testing process.

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

International Nuclear Information System (INIS)

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

Outcomes After Orbital Atherectomy of Severely Calcified Left Main Lesions: Analysis of the ORBIT II Study.

Science.gov (United States)

Lee, Michael S; Shlofmitz, Evan; Shlofmitz, Richard; Sahni, Sheila; Martinsen, Brad; Chambers, Jeffrey

2016-09-01

The ORBIT II trial reported excellent outcomes in patients with severely calcified coronary lesions treated with orbital atherectomy. Severe calcification of the left main (LM) artery represents a complex coronary lesion subset. This study evaluated the safety and efficacy of coronary orbital atherectomy to prepare severely calcified protected LM artery lesions for stent placement. The ORBIT II trial was a prospective, multicenter clinical trial that enrolled 443 patients with severely calcified coronary lesions in the United States. The major adverse cardiac event (MACE) rate through 2 years post procedure, defined by cardiac death, myocardial infarction (CK-MB >3x upper limit of normal with or without a new pathologic Q-wave) and target-vessel revascularization, was compared in the LM and non-left main (NLM) groups. Among the 443 patients, a total of 10 underwent orbital atherectomy of protected LM artery lesions. At 2 years, there was no significant difference in the 2-year MACE rate in the LM and NLM groups (30.0% vs 19.1%, respectively; P=.36). Cardiac death was low in both groups (0% vs 4.4%, respectively; P=.99). Myocardial infarction occurred within 30 days in both groups (10.0% vs 9.7%, respectively; P=.99). Severe dissection, perforation, persistent slow flow, and persistent no reflow did not occur in the LM group. Abrupt closure occurred in 1 patient in the LM group. Orbital atherectomy for patients with heavily calcified LM coronary artery lesions is safe and feasible. Further studies are needed to assess the safety and efficacy of orbital atherectomy in patients with severely calcified LM artery lesions.

Vehicle systems and payload requirements evaluation. [computer programs for identifying launch vehicle system requirements

Science.gov (United States)

Rea, F. G.; Pittenger, J. L.; Conlon, R. J.; Allen, J. D.

1975-01-01

Techniques developed for identifying launch vehicle system requirements for NASA automated space missions are discussed. Emphasis is placed on development of computer programs and investigation of astrionics for OSS missions and Scout. The Earth Orbit Mission Program - 1 which performs linear error analysis of launch vehicle dispersions for both vehicle and navigation system factors is described along with the Interactive Graphic Orbit Selection program which allows the user to select orbits which satisfy mission requirements and to evaluate the necessary injection accuracy.

Orbital Resonances in the Vinti Solution

Science.gov (United States)

Zurita, L. D.

As space becomes more congested, contested, and competitive, high-accuracy orbital predictions become critical for space operations. Current orbit propagators use the two-body solution with perturbations added, which have significant error growth when numerically integrated for long time periods. The Vinti Solution is a more accurate model than the two-body problem because it also accounts for the equatorial bulge of the Earth. Unfortunately, the Vinti solution contains small divisors near orbital resonances in the perturbative terms of the Hamiltonian, which lead to inaccurate orbital predictions. One approach to avoid the small divisors is to apply transformation theory, which is presented in this research. The methodology of this research is to identify the perturbative terms of the Vinti Solution, perform a coordinate transformation, and derive the new equations of motion for the Vinti system near orbital resonances. An analysis of these equations of motion offers insight into the dynamics found near orbital resonances. The analysis in this research focuses on the 2:1 resonance, which includes the Global Positioning System. The phase portrait of a nominal Global Positioning System satellite orbit is found to contain a libration region and a chaotic region. Further analysis shows that the dynamics of the 2:1 resonance affects orbits with semi-major axes ranging from -5.0 to +5.4 kilometers from an exactly 2:1 resonant orbit. Truth orbits of seven Global Positioning System satellites are produced for 10 years. Two of the satellites are found to be outside of the resonance region and three are found to be influenced by the libration dynamics of the resonance. The final satellite is found to be influenced by the chaotic dynamics of the resonance. This research provides a method of avoiding the small divisors found in the perturbative terms of the Vinti Solution near orbital resonances.

Optical Orbit Determination of a Geosynchronous Earth Orbit Satellite Effected by Baseline Distances between Various Ground-based Tracking Stations Ⅱ: COMS Case with Analysis of Actual Observation Data

Directory of Open Access Journals (Sweden)

Ju Young Son

2015-09-01

Full Text Available We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS, a Geostationary Earth Orbit (GEO satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO of the Korea Astronomy and Space Science Institute (KASI, Optical Wide field Patrol (OWL at KASI, and the Chungbuk National University Observatory (CNUO from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.

A standard library for modeling satellite orbits on a microcomputer

Science.gov (United States)

Beutel, Kenneth L.

1988-03-01

Introductory students of astrodynamics and the space environment are required to have a fundamental understanding of the kinematic behavior of satellite orbits. This thesis develops a standard library that contains the basic formulas for modeling earth orbiting satellites. This library is used as a basis for implementing a satellite motion simulator that can be used to demonstrate orbital phenomena in the classroom. Surveyed are the equations of orbital elements, coordinate systems and analytic formulas, which are made into a standard method for modeling earth orbiting satellites. The standard library is written in the C programming language and is designed to be highly portable between a variety of computer environments. The simulation draws heavily on the standards established by the library to produce a graphics-based orbit simulation program written for the Apple Macintosh computer. The simulation demonstrates the utility of the standard library functions but, because of its extensive use of the Macintosh user interface, is not portable to other operating systems.

Analysis of plasma equilibrium based on orbit-driven current density profile in steady-state plasma on QUEST

Energy Technology Data Exchange (ETDEWEB)

Nakamura, K., E-mail: nakamura@triam.kyushu-u.ac.jp [RIAM, Kyushu University, Kasuga 816-8580 (Japan); Alam, M.M. [IGSES, Kyushu University, Kasuga 816-8580 (Japan); Jiang, Y.Z. [Tsinghua University, Beijing 100084 (China); Mitarai, O. [Tokai University, Kumamoto 862-8652 (Japan); Kurihara, K.; Kawamata, Y.; Sueoka, M.; Takechi, M. [Japan Atomic Energy Agency, Naka 311-0193 (Japan); Hasegawa, M.; Tokunaga, K.; Araki, K.; Zushi, H.; Hanada, K.; Fujisawa, A.; Idei, H.; Nagashima, Y.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Nagata, T. [RIAM, Kyushu University, Kasuga 816-8580 (Japan); and others

2016-11-01

Highlights: • High energy particle guiding center orbit is calculated as a contour plot of conserved variable. • Current density profile is analyzed based on the orbit-driven current. • Plasma equilibrium is reconstructed by considering the hollow current profile. - Abstract: In the present RF-driven (ECCD) steady-state plasma on QUEST (B{sub t} = 0.25 T, R = 0.68 m, a = 0.40 m), plasma current seems to flow in the open magnetic surface outside of the closed magnetic surface in the low-field region according to plasma current fitting (PCF) method. We consider that the current in the open magnetic surface is due to orbit-driven current by high-energy particles in RF-driven plasma. So based on the analysis of current density profile based on the orbit-driven current, plasma equilibrium is to be calculated. We calculated high energy particles guiding center orbits as a contour plot of conserved variable in Hamiltonian formulation and considered particles initial position with different levels of energy and pitch angles that satisfy resonance condition. Then the profile of orbit-driven current is estimated by multiplying the particle density on the resonance surface and the velocity on the orbits. This analysis shows negative current near the magnetic axis and hollow current profile is expected even if pressure driven current is considered. Considering the hollow current profile shifted toward the low-field region, the equilibrium is fitted by J-EFIT coded by MATLAB.

The History of Orbiter Corrosion Control (1981 - 2011)

Science.gov (United States)

Russell, Richard W.

2014-01-01

After 135 missions and 30 years the Orbiter fleet was retired in 2011. Working with Orbiter project management and a world class engineering team the CCRB was successful in providing successful sustaining engineering support for approximately 20 years. Lessons learned from the Orbiter program have aided NASA and contractor engineers in the design and manufacture of new spacecraft so that exploration of space can continue. The Orbiters are proudly being displayed for all the public to see in New York City, Washington D.C., Los Angeles, and at the Kennedy Space Center in Florida.

Meta-orbital transition in heavy-fermion systems. Analysis by dynamical mean field theory and self-consistent renormalization theory of orbital fluctuations

International Nuclear Information System (INIS)

Hattori, Kazumasa

2010-01-01

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 n f 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 CeAl 2 , CeCu 2 Si 2 , CeCu 2 Ge 2 , and related compounds, which all have low-lying crystalline-electric-field excited states. (author)

A user's guide to the Flexible Spacecraft Dynamics and Control Program

Science.gov (United States)

Fedor, J. V.

1984-01-01

A guide to the use of the Flexible Spacecraft Dynamics Program (FSD) is presented covering input requirements, control words, orbit generation, spacecraft description and simulation options, and output definition. The program can be used in dynamics and control analysis as well as in orbit support of deployment and control of spacecraft. The program is applicable to inertially oriented spinning, Earth oriented or gravity gradient stabilized spacecraft. Internal and external environmental effects can be simulated.

Sturdy on Orbital TIG Welding Properties for Nuclear Fuel Test Rod

International Nuclear Information System (INIS)

Joung, Changyoung; Hong, Jintae; Kim, Kahye; Huh, Sungho

2014-01-01

We developed a precision TIG welding system that is able to weld the seam between end-caps and a fuel cladding tube for the nuclear fuel test rod and rig. This system can be mainly classified into an orbital TIG welder (AMI, M-207A) and a pressure chamber. The orbital TIG welder can be independently used, and it consists of a power supply unit, a microprocessor, water cooling unit, a gas supply unit and an orbital weld head. In this welder, the power supply unit mainly supplies GTAW power for a welding specimen and controls an arc starting of high frequency, supping of purge gas, arc rotation through the orbital TIG welding head, and automatic timing functions. In addition, the pressure chamber is used to make the welded surface of the cladding specimen clean with the inert gas filled inside the chamber. To precisely weld the cladding tube, a welding process needs to establish a schedule program for an orbital TIG welding. Therefore, the weld tests were performed on a cladding tube and dummy rods under various conditions. This paper describes not only test results on parameters of the purge gas flow rates and the chamber gas pressures for the orbital TIG welding, but also test results on the program establishment of an orbital TIG welding system to weld the fuel test rods. Various welding tests were performed to develop the orbital TIG welding techniques for the nuclear fuel test rod. The width of HAZ of a cladding specimen welded with the identical power during an orbital TIG welding cycle was continuously increased from a welded start-point to a weld end-point because of heat accumulation. The welding effect of the PGFR and CGP shows a relatively large difference for FSS and LSS. Each hole on the cladding specimens was formed in the 1bar CGP with the 20L/min PGFR but not made in the case of the PGFR of 10L/min in the CGP of 2bar. The optimum schedule program of the orbital TIG welding system to weld the nuclear fuel test rod was established through the program

Sturdy on Orbital TIG Welding Properties for Nuclear Fuel Test Rod

Energy Technology Data Exchange (ETDEWEB)

Joung, Changyoung; Hong, Jintae; Kim, Kahye; Huh, Sungho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

We developed a precision TIG welding system that is able to weld the seam between end-caps and a fuel cladding tube for the nuclear fuel test rod and rig. This system can be mainly classified into an orbital TIG welder (AMI, M-207A) and a pressure chamber. The orbital TIG welder can be independently used, and it consists of a power supply unit, a microprocessor, water cooling unit, a gas supply unit and an orbital weld head. In this welder, the power supply unit mainly supplies GTAW power for a welding specimen and controls an arc starting of high frequency, supping of purge gas, arc rotation through the orbital TIG welding head, and automatic timing functions. In addition, the pressure chamber is used to make the welded surface of the cladding specimen clean with the inert gas filled inside the chamber. To precisely weld the cladding tube, a welding process needs to establish a schedule program for an orbital TIG welding. Therefore, the weld tests were performed on a cladding tube and dummy rods under various conditions. This paper describes not only test results on parameters of the purge gas flow rates and the chamber gas pressures for the orbital TIG welding, but also test results on the program establishment of an orbital TIG welding system to weld the fuel test rods. Various welding tests were performed to develop the orbital TIG welding techniques for the nuclear fuel test rod. The width of HAZ of a cladding specimen welded with the identical power during an orbital TIG welding cycle was continuously increased from a welded start-point to a weld end-point because of heat accumulation. The welding effect of the PGFR and CGP shows a relatively large difference for FSS and LSS. Each hole on the cladding specimens was formed in the 1bar CGP with the 20L/min PGFR but not made in the case of the PGFR of 10L/min in the CGP of 2bar. The optimum schedule program of the orbital TIG welding system to weld the nuclear fuel test rod was established through the program

NASA Orbital Debris Baseline Populations

Science.gov (United States)

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.

Primary orbital fracture repair: development and validation of tools for morphologic and functional analysis.

Science.gov (United States)

Hontscharuk, Rayisa; Fialkov, Jeffrey A; Binhammer, Paul A; McMillan, Catherine R; Antonyshyn, Oleh

2012-07-01

The purpose of this study was to develop and validate a technique for objective quantitative evaluation of outcomes of orbital reconstruction. Facial three-dimensional images were captured using a Vectra three-dimensional camera. Morphometric analysis was based on interactive anthropometric identification. The analysis was applied to a population of healthy adults (n = 13) and a population of patients following primary repair of unilateral orbital fractures (n = 13). Morphologic results following reconstruction were evaluated by identifying residual asymmetries. All subjects further completed the Derriford Appearance Questionnaire and the Orbital Appearance and Function Questionnaire.Normative reference values for periorbital asymmetry were determined in a reference population. The mean asymmetry was less than 1.6 mm for each measured morphologic feature. In the trauma population, primary orbital reconstruction effectively restored normal periorbital symmetry in 16 of 20 measured parameters. The fracture population showed no significant differences in the degree of asymmetry in globe projection, lower eyelid position, or ciliary margin length.The overall DAS59 scores were significantly higher in the fracture population (P = 0.04). This was due to significantly higher physical distress and dysfunction scores (P = 0.02), as well as a trend toward higher general and social self-consciousness scores (P = 0.06). No significant difference in facial self-consciousness was noted (P = 0.21). Thus, although primary orbital reconstruction was effective in restoring periorbital morphology, patients still experienced a higher level of physical distress and dysfunction than their nontraumatized counterparts. This was in accordance with patient self-report, which indicated that a greater percentage of patients were significantly bothered by functional outcomes postoperatively as opposed to appearance.

Analysis for orbital rendezvous of Chang'E-5 using SBI technique

Science.gov (United States)

Huang, Y.; Shan, Q.; Li, P.

2016-12-01

Chang'E-5 will be launched in later 2017/early 2018 using a new generation rocket from Wenchang satellite launch center, Hainan, China. It is a lunar sampling return mission, and it is the first time for China to carry out orbital rendezvous and docking in the Moon. How to achieve orbital rendezvous successfully in the Moon is very important in Chang'E-5 mission. Orbital rendezvous will be implemented between an orbiter and an ascender 200 km above the Moon. The ground tracking techniques include range, Doppler and VLBI, and they will be used to track the orbiter and the ascender when the ascender is about 70 km farther away from the orbiter. Later the ascender will approach the orbiter automatically. As a successful example, in Chang'E-3, the differential phase delay (delta delay) data between the rover and the lander are obtained with a random error of about 1 ps, and the relative position of the rover is determined with an accuracy of several meters by using same beam VLBI (SBI) technique. Here the application of the SBI technique for Chang'E-5 orbital rendezvous is discussed. SBI technique can be used to track the orbiter and the ascender simultaneously when they are in the same beam. Delta delay of the two probes can be derived, and the measurement accuracy is much higher than that of the traditional VLBI data because of the cancelation of common errors. Theoretically it can result in a more accurate relative orbit between the two probes. In the simulation, different strategies are discussed to analyze the contribution of SBI data to the orbit accuracy improvement especially relative orbit between the orbiter and ascender. The simulation results show that the relative position accuracy of the orbiter and ascender can reach about 1 m with delta delay data of 10 ps.

NASA Safety Standard: Guidelines and Assessment Procedures for Limiting Orbital Debris

Science.gov (United States)

1995-01-01

Collision with orbital debris is a hazard of growing concern as historically accepted practices and procedures have allowed man-made objects to accumulate in orbit. To limit future debris generation, NASA Management Instruction (NMI) 1700.8, 'Policy to Limit Orbital Debris Generation,' was issued in April of 1993. The NMI requires each program to conduct a formal assessment of the potential to generate orbital debris. This document serves as a companion to NMI 1700.08 and provides each NASA program with specific guidelines and assessment methods to assure compliance with the NMI. Each main debris assessment issue (e.g., Post Mission Disposal) is developed in a separate chapter.

Guidance system operations plan for manned CM earth orbital missions using program Skylark 1. Section 2: Data links

Science.gov (United States)

Hamilton, M. H.

1972-01-01

A computer program to define the digital uplink and downlink for use in manned command module orbital missions is presented. The subjects discussed are: (1) digital uplink to command module, (2) CMC digital downlink, (3) downlist formats, (4) description of telemetered qualities, (5) flagbits, and (6) effects of Fresh Start (V36) and Hardware Restart on flagword and channel bits.

Introducing PROFESS 2.0: A parallelized, fully linear scaling program for orbital-free density functional theory calculations

Science.gov (United States)

Hung, Linda; Huang, Chen; Shin, Ilgyou; Ho, Gregory S.; Lignères, Vincent L.; Carter, Emily A.

2010-12-01

Orbital-free density functional theory (OFDFT) is a first principles quantum mechanics method to find the ground-state energy of a system by variationally minimizing with respect to the electron density. No orbitals are used in the evaluation of the kinetic energy (unlike Kohn-Sham DFT), and the method scales nearly linearly with the size of the system. The PRinceton Orbital-Free Electronic Structure Software (PROFESS) uses OFDFT to model materials from the atomic scale to the mesoscale. This new version of PROFESS allows the study of larger systems with two significant changes: PROFESS is now parallelized, and the ion-electron and ion-ion terms scale quasilinearly, instead of quadratically as in PROFESS v1 (L. Hung and E.A. Carter, Chem. Phys. Lett. 475 (2009) 163). At the start of a run, PROFESS reads the various input files that describe the geometry of the system (ion positions and cell dimensions), the type of elements (defined by electron-ion pseudopotentials), the actions you want it to perform (minimize with respect to electron density and/or ion positions and/or cell lattice vectors), and the various options for the computation (such as which functionals you want it to use). Based on these inputs, PROFESS sets up a computation and performs the appropriate optimizations. Energies, forces, stresses, material geometries, and electron density configurations are some of the values that can be output throughout the optimization. New version program summaryProgram Title: PROFESS Catalogue identifier: AEBN_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBN_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 68 721 No. of bytes in distributed program, including test data, etc.: 1 708 547 Distribution format: tar.gz Programming language: Fortran 90 Computer

Retrieval of RTG'S in earth orbit

International Nuclear Information System (INIS)

Raab, B.; Frieder, M.A.; Skrabek, A.

1982-01-01

Since 1961, some ten Radioisotope Thermoelectric Generators (RTG's) have been placed into a variety of spacecraft which are now in earth orbit. All of these spacecraft are in orbits with lifetimes in excess of 100 years and pose no risk. However, since most of these spacecraft are no longer being actively used, these may be subject to an active removal program to reduce the population of objects in space. Therefore, a study was undertaken to evaluate the feasibility of retrieving or disposing of spacecraft with RTGs on board. Intervention scenarios are developed and an orbital rendezvous vehicle is conceptualized. The costs of RTG retrieval are derived and compared to the costs of RTG disposal, i.e., boost to a higher, multi-millenium-lifetime orbit, and are found to be not significantly different

Suspended Cell Culture ANalysis (SCAN) Tool to Enhance ISS On-Orbit Capabilities, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Aurora Flight Sciences and partner, Draper Laboratory, propose to develop an on-orbit immuno-based label-free Suspension Cell Culture ANalysis tool, SCAN tool, which...

Report of the NASA Science Definition Team for the Mars Science Orbiter (MSO)

Science.gov (United States)

Smith, Michael

2007-01-01

NASA is considering that its Mars Exploration Program (MEP) will launch an orbiter to Mars in the 2013 launch opportunity. To further explore this opportunity, NASA has formed a Science Definition Team (SDT) for this orbiter mission, provisionally called the Mars Science Orbiter (MSO). Membership and leadership of the SDT are given in Appendix 1. Dr. Michael D. Smith chaired the SDT. The purpose of the SDT was to define the: 1) Scientific objectives of an MSO mission to be launched to Mars no earlier than the 2013 launch opportunity, building on the findings for Plan A [Atmospheric Signatures and Near-Surface Change] of the Mars Exploration Program Analysis Group (MEPAG) Second Science Analysis Group (SAG-2); 2) Science requirements of instruments that are most likely to make high priority measurements from the MSO platform, giving due consideration to the likely mission, spacecraft and programmatic constraints. The possibilities and opportunities for international partners to provide the needed instrumentation should be considered; 3) Desired orbits and mission profile for optimal scientific return in support of the scientific objectives, and the likely practical capabilities and the potential constraints defined by the science requirements; and 4) Potential science synergies with, or support for, future missions, such as a Mars Sample Return. This shall include imaging for evaluation and certification of future landing sites. As a starting point, the SDT was charged to assume spacecraft capabilities similar to those of the Mars Reconnaissance Orbiter (MRO). The SDT was further charged to assume that MSO would be scoped to support telecommunications relay of data from, and commands to, landed assets, over a 10 Earth year period following orbit insertion. Missions supported by MSO may include planned international missions such as EXOMARS. The MSO SDT study was conducted during October - December 2007. The SDT was directed to complete its work by December 15, 2007

Ecosystem Analysis Program

International Nuclear Information System (INIS)

Burgess, R.L.

1978-01-01

Progress is reported on the following research programs: analysis and modeling of ecosystems; EDFB/IBP data center; biome analysis studies; land/water interaction studies; and computer programs for development of models

A simulation of the Four-way lunar Lander-Orbiter tracking mode for the Chang'E-5 mission

Science.gov (United States)

Li, Fei; Ye, Mao; Yan, Jianguo; Hao, Weifeng; Barriot, Jean-Pierre

2016-06-01

The Chang'E-5 mission is the third phase of the Chinese Lunar Exploration Program and will collect and return lunar samples. After sampling, the Orbiter and the ascent vehicle will rendezvous and dock, and both spacecraft will require high precision orbit navigation. In this paper, we present a novel tracking mode-Four-way lunar Lander-Orbiter tracking that possibly can be employed during the Chang'E-5 mission. The mathematical formulas for the Four-way lunar Lander-Orbiter tracking mode are given and implemented in our newly-designed lunar spacecraft orbit determination and gravity field recovery software, the LUnar Gravity REcovery and Analysis Software/System (LUGREAS). The simulated observables permit analysis of the potential contribution Four-way lunar Lander-Orbiter tracking could make to precision orbit determination for the Orbiter. Our results show that the Four-way lunar Lander-Orbiter Range Rate has better geometric constraint on the orbit, and is more sensitive than the traditional two-way range rate that only tracks data between the Earth station and lunar Orbiter. After combining the Four-way lunar Lander-Orbiter Range Rate data with the traditional two-way range rate data and considering the Lander position error and lunar gravity field error, the accuracy of precision orbit determination for the Orbiter in the simulation was improved significantly, with the biggest improvement being one order of magnitude, and the Lander position could be constrained to sub-meter level. This new tracking mode could provide a reference for the Chang'E-5 mission and have enormous potential for the positioning of future lunar farside Lander due to its relay characteristic.

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

Science.gov (United States)

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

Hypersonic Navier-Stokes Comparisons to Orbiter Flight Data

Science.gov (United States)

Candler, Graham V.; Campbell, Charles H.

2010-01-01

During the STS-119 flight of Space Shuttle Discovery, two sets of surface temperature measurements were made. Under the HYTHIRM program3 quantitative thermal images of the windward side of the Orbiter with a were taken. In addition, the Boundary Layer Transition Flight Experiment 4 made thermocouple measurements at discrete locations on the Orbiter wind side. Most of these measurements were made downstream of a surface protuberance designed to trip the boundary layer to turbulent flow. In this paper, we use the US3D computational fluid dynamics code to simulate the Orbiter flow field at conditions corresponding to the STS-119 re-entry. We employ a standard two-temperature, five-species finite-rate model for high-temperature air, and the surface catalysis model of Stewart.1 This work is similar to the analysis of Wood et al . 2 except that we use a different approach for modeling turbulent flow. We use the one-equation Spalart-Allmaras turbulence model8 with compressibility corrections 9 and an approach for tripping the boundary layer at discrete locations. In general, the comparison between the simulations and flight data is remarkably good

History of Satellite Orbit Determination at NSWCDD

Science.gov (United States)

2018-01-31

meeting of the Satellite Division of ION, Palm Springs, CA., 12–15 Sep 1995. Hughey, Raymond H., Jr., “ History of Mathematics and Computing Technology ...TR-17/229 HISTORY OF SATELLITE ORBIT DETERMINATION AT NSWCDD BY EVERETT R. SWIFT WARFARE SYSTEMS ENGINEERING AND INTEGRATION...AND SUBTITLE History of Satellite Orbit Determination at NSWCDD 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

The Coupled Orbit-Attitude Dynamics and Control of Electric Sail in Displaced Solar Orbits

Directory of Open Access Journals (Sweden)

Mingying Huo

2017-01-01

Full Text Available Displaced solar orbits for spacecraft propelled by electric sails are investigated. Since the propulsive thrust is induced by the sail attitude, the orbital and attitude dynamics of electric-sail-based spacecraft are coupled and required to be investigated together. However, the coupled dynamics and control of electric sails have not been discussed in most published literatures. In this paper, the equilibrium point of the coupled dynamical system in displaced orbit is obtained, and its stability is analyzed through a linearization. The results of stability analysis show that only some of the orbits are marginally stable. For unstable displaced orbits, linear quadratic regulator is employed to control the coupled attitude-orbit system. Numerical simulations show that the proposed strategy can control the coupled system and a small torque can stabilize both the attitude and orbit. In order to generate the control force and torque, the voltage distribution problem is studied in an optimal framework. The numerical results show that the control force and torque of electric sail can be realized by adjusting the voltage distribution of charged tethers.

Application of orbital strong magnet in the extraction of deep orbital magnetic foreign bodies

Directory of Open Access Journals (Sweden)

Jin-Chen Jia

2017-12-01

Full Text Available AIM: To investigate the surgical method and efficacy of extraction of deep orbital magnetic foreign bodies by mean of an orbital strong magnet. METHODS: A retrospective analysis of clinical data of patients with deep orbital magnetic foreign bodies(OMFBin Hebei Eye Hospital from June 2014 to May 2017 was processed. A total of 23 eyes were enrolled, among them, 14 eyes of extraorbital OMFB, 9 eyes of intraorbital OMFB. The rate of extraction of foreign bodies and the postoperative complications were observed. RESULTS: All eyes of intraorbital foreign bodies were successfully extracted with 100% success rate. Twelve of 14 eyes of extraorbital foreign bodies were extracted with 86% success rate. Mild orbital hemorrhage were found in 2 eyes. There was no other obvious complication such as visual loss, orbital massive hemorrhage or limited ocular movement. CONCLUSION: It's an ideal surgical method to extract the deep orbital magnetic foreign bodies by mean of an orbital strong magnet, with mini-injury, high success rate, short duration and few complications.

Particle orbit tracking on a parallel computer: Hypertrack

International Nuclear Information System (INIS)

Cole, B.; Bourianoff, G.; Pilat, F.; Talman, R.

1991-05-01

A program has been written which performs particle orbit tracking on the Intel iPSC/860 distributed memory parallel computer. The tracking is performed using a thin element approach. A brief description of the structure and performance of the code is presented, along with applications of the code to the analysis of accelerator lattices for the SSC. The concept of ''ensemble tracking'', i.e. the tracking of ensemble averages of noninteracting particles, such as the emittance, is presented. Preliminary results of such studies will be presented. 2 refs., 6 figs

Dynamic and reduced-dynamic precise orbit determination of satellites in low earth orbits

International Nuclear Information System (INIS)

Swatschina, P.

2009-01-01

presented. The additional parameters are estimated within the adjustment process. In order to regulate their impact on the dynamic solution, the empirical parameters are assigned statistical a priori information. This allows for a perfect synergy of the advanced knowledge of spacecraft dynamics and the high accuracy of the GPS measurements. The developed routines have been implemented in a computer program and tested for CHAMP and GRACE. The applied strategies proved to be highly efficient, robust and flexible. The attained orbit solutions are validated against solutions of other well-established POD methods. It is shown, that dynamic POD delivers accuracies at the 1 dm level for orbital lengths of up to 90 minutes. Furthermore, employing an adequate number of pseudo-stochastic parameters with optimal weighting, reduced-dynamic orbit determination is a powerful strategy for LEO POD. Orbital arcs over a whole day can be generated with an accuracy of up to 4.5 cm RMS. (author) [de

Forward Technology Solar Cell Experiment First On-Orbit Data

Science.gov (United States)

Walters, R. J.; Garner, J. C.; Lam, S. N.; Vazquez, J. A.; Braun, W. R.; Ruth, R. E.; Warner, J. H.; Lorentzen, J. R.; Messenger, S. R.; Bruninga, R.;

Simulation and correction of the closed orbit in the cooler synchrotron COSY

International Nuclear Information System (INIS)

Dinev, D.

1990-11-01

In this paper the problem of COSY closed orbit control and its correction is discussed. The results of a simulation of the COSY closed orbit and its correction using different correction methods are given. The interactive computer program ORBIT, created especially for the simulation and correction of the COSY closed orbit, is described. The paper includes as well a survey of the orbit correction methods and related topics. (orig.)

Orbital motion in pre-main sequence binaries

Energy Technology Data Exchange (ETDEWEB)

Schaefer, G. H. [The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Prato, L. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Simon, M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States); Patience, J., E-mail: schaefer@chara-array.org [Astrophysics Group, School of Physics, University of Exeter, Exeter, EX4 4QL (United Kingdom)

2014-06-01

We present results from our ongoing program to map the visual orbits of pre-main sequence (PMS) binaries in the Taurus star forming region using adaptive optics imaging at the Keck Observatory. We combine our results with measurements reported in the literature to analyze the orbital motion for each binary. We present preliminary orbits for DF Tau, T Tau S, ZZ Tau, and the Pleiades binary HBC 351. Seven additional binaries show curvature in their relative motion. Currently, we can place lower limits on the orbital periods for these systems; full solutions will be possible with more orbital coverage. Five other binaries show motion that is indistinguishable from linear motion. We suspect that these systems are bound and might show curvature with additional measurements in the future. The observations reported herein lay critical groundwork toward the goal of measuring precise masses for low-mass PMS stars.

GLONASS Orbits in Teqc: Methodology and Future Extension for Using SP3 Orbits

Science.gov (United States)

Estey, L.; Wier, S.

2011-12-01

UNAVCO's teqc software package provides translation of a wide variety of GNSS receiver formats, metadata editing (either during translation to RINEX or on existing RINEX files), time-windowing and epoch decimation editing, and quality check (qc) analysis. Teqc is used extensively in GNSS pre-processing, and is designed to handle mixed satellite constellations, such as GPS, GLONASS, Galileo, and SBAS. The latest release of teqc adds GLONASS orbit calculations using GLONASS broadcast navigation messages, read from RINEX file format, during qc. The ephemerides for each GLONASS SV have time and orbit position in Earth-centered, Earth-fixed x, y, and z coordinates. Following Schenewerk [2003], we use trigonometric interpolation, essentially a fit of a partial sum of the Fourier series for each time-varying cartesian orbital component, allowing estimates of orbit positions at most GLONASS observation times. Tests show the interpolated GLONASS orbits made from the broadcast messages diverge from final orbits little more than the same differences using GPS orbits computed from their broadcast messages. Since GLONASS ephemerides do not use Keplerian orbital elements, GLONASS SV orbits can only be interpolated using this method for time intervals when an adequate sequence of ephemerides are available. For typical daily navigation messages collected at a single sit, when a GLONASS SV is in view less than three hours, that SV's signals are generally not used by teqc due to less precise orbit positions. Teqc quality control including SV position can now use GPS alone, GLONASS alone, or the joint solution. Future work will extend teqc to use SP3 format files, such as the IGS final orbit files, and SBAS data, which have broadcast ephemerides with elements similar to GLONASS.

A high-fidelity N-body ephemeris generator for satellites in Earth orbit

Science.gov (United States)

Simmons, David R.

1991-10-01

A program is currently used for mission planning called the Analytic Satellite Ephemeris Program (ASEP), which produces projected data for orbits that remain fairly close to Earth. Lunar and solar perturbations are taken into account in another program called GRAVE. This project is a revision of GRAVE which incorporates more flexible means of input for initial data, provides additional kinds of output information, and makes use of structured programming techniques to make the program more understandable and reliable. The computer program ORBIT was tested against tracking data for the first 313 days of operation of the CRRES satellite. A sample graph is given comparing the semi-major axis calculated by the program with the values supplied by NORAD. When calculated for points at which CRRES passes through the ascending node, the argument of perigee, the right ascension of the ascending node, and the mean anomaly all stay within about a degree of the corresponding values from NORAD; the inclination of the orbital plane is much closer. The program value of the eccentricity is in error by no more than 0.0002.

The ground support computer and in-orbit survey data analysis program for the SEEP experiment

International Nuclear Information System (INIS)

Voss, H.D.; Datlowe, D.W.; Mobilia, J.; Roselle, S.N.

1985-01-01

The ground support computer equipment (GSE) and production survey plot and analysis software are described for the Stimulated Emissions of Energetic Particles (SEEP) experiment on the S81-1 satellite. A general purpose satellite data acquisition circuit was developed based on a Z-80 portable microcomputer. By simply changing instrument control software and electrical connectors, automatic testing and control of the various SEEP instruments was accomplished. A new feature incorporated into the SEEP data analysis phase was the development of a correlative data base for all of the SEEP instruments. A CPU efficient survey plot program (with ephemeris) was developed to display the approximate 3100 hours of data, with a time resolution of 0.5 sec, from the ten instrument sensors. The details of the general purpose multigraph algorithms and plot formats are presented. For the first time new associations are being investigated of simultaneous particle, X-ray, optical and plasma density satellite measurements

Environmental studies using earth orbital photography

Energy Technology Data Exchange (ETDEWEB)

Wobber, F J

1969-01-01

Orbital remote sensing, and particularly orbital photography, can provide immediately useful data for scientists familiar with applying aerial photographic techniques to environmental problems. Despite the expansion of analytical techniques in the earth sciences, the environmental data base has remained relatively static compared with increased information needs because of the difficulty of effective worldwide surveys and the high cost of timely data collection. Color, color infrared and black and white space photographs obtained incident to the Gemini and Apollo programs provide unique synoptic tools for analyzing modern environments and processes, and data that cannot be duplicated by aerial photographic mosaics. Principal advantages of orbital surveys include repetitious worldwide coverage promising environmental synthesis within the full spectrum of seasonal contrasts, and synoptic observations on a scale generally impossible from aircraft. The general categories of environmental data that can be extracted from orbital photography are summarized. 26 references, 37 figures, 3 tables.

Orbit Determination of Spacecraft in Earth-Moon L1 and L2 Libration Point Orbits

Science.gov (United States)

Woodard, Mark; Cosgrove, Daniel; Morinelli, Patrick; Marchese, Jeff; Owens, Brandon; Folta, David

2011-01-01

measurements that would be needed to meet the required orbit determination accuracies. Analysts used the Orbit Determination Error Analysis System (ODEAS) to perform covariance analyses using various tracking data schedules. From this analysis, it was determined that 3.5 hours of DSN TRK-2-34 range and Doppler tracking data every other day would suffice to meet the predictive orbit knowledge accuracies in the Lissajous region. The results of this analysis are presented. Both GTDS and ODTK have high-fidelity environmental orbit force models that allow for very accurate orbit estimation in the lunar Lissajous regime. These models include solar radiation pressure, Earth and Moon gravity models, third body gravitational effects from the Sun, and to a lesser extent third body gravitational effects from Jupiter, Venus, Saturn, and Mars. Increased position and velocity uncertainties following each maneuver, due to small execution performance errors, requires that several days of post-maneuver tracking data be processed to converge on an accurate post-maneuver orbit solution. The effects of maneuvers on orbit determination accuracy will be presented, including a comparison of the batch least squares technique to the extended Kalman filter/smoother technique. We will present the maneuver calibration results derived from processing post-maneuver tracking data. A dominant error in the orbit estimation process is the uncertainty in solar radiation pressure and the resultant force on the spacecraft. An estimation of this value can include many related factors, such as the uncertainty in spacecraft reflectivity and surface area which is a function of spacecraft orientation (spin-axis attitude), uncertainty in spacecraft wet mass, and potential seasonal variability due to the changing direction of the Sun line relative to the Earth-Moon Lissajous reference frame. In addition, each spacecraft occasionally enters into Earth or Moon penumbra or umbra and these shadow crossings reduche solar

Subseabed-disposal program: systems-analysis program plan

International Nuclear Information System (INIS)

Klett, R.D.

1981-03-01

This report contains an overview of the Subseabed Nuclear Waste Disposal Program systems analysis program plan, and includes sensitivity, safety, optimization, and cost/benefit analyses. Details of the primary barrier sensitivity analysis and the data acquisition and modeling cost/benefit studies are given, as well as the schedule through the technical, environmental, and engineering feasibility phases of the program

Instantaneous Purified Orbit: A New Tool for Analysis of Nonstationary Vibration of Rotor System

Directory of Open Access Journals (Sweden)

Shi Dongfeng

2001-01-01

Full Text Available In some circumstances, vibration signals of large rotating machinery possess time-varying characteristics to some extent. Traditional diagnosis methods, such as FFT spectrum and orbit diagram, are confronted with a huge challenge to deal with this problem. This work aims at studying the four intrinsic drawbacks of conventional vibration signal processing method and instantaneous purified orbit (IPO on the basis of improved Fourier spectrum (IFS to analyze nonstationary vibration. On account of integration, the benefits of short period Fourier transform (SPFT and regular holospectrum, this method can intuitively reflect vibration characteristics of’a rotor system by means of parameter analysis for corresponding frequency ellipses. Practical examples, such as transient vibration in run-up stages and bistable condition of rotor show that IPO is a powerful tool for diagnosis and analysis of the vibration behavior of rotor systems.

THE NASA-UC ETA-EARTH PROGRAM. III. A SUPER-EARTH ORBITING HD 97658 AND A NEPTUNE-MASS PLANET ORBITING Gl 785

International Nuclear Information System (INIS)

Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Johnson, John Asher; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E.

2011-01-01

We report the discovery of planets orbiting two bright, nearby early K dwarf stars, HD 97658 and Gl 785. These planets were detected by Keplerian modeling of radial velocities measured with Keck-HIRES for the NASA-UC Eta-Earth Survey. HD 97658 b is a close-in super-Earth with minimum mass Msin i = 8.2 ± 1.2 M + , orbital period P = 9.494 ± 0.005 days, and an orbit that is consistent with circular. Gl 785 b is a Neptune-mass planet with Msin i = 21.6 ± 2.0 M + , P = 74.39 ± 0.12 days, and orbital eccentricity e = 0.30 ± 0.09. Photometric observations with the T12 0.8 m automatic photometric telescope at Fairborn Observatory show that HD 97658 is photometrically constant at the radial velocity period to 0.09 mmag, supporting the existence of the planet.

Two-craft Coulomb formation study about circular orbits and libration points

Science.gov (United States)

Inampudi, Ravi Kishore

This dissertation investigates the dynamics and control of a two-craft Coulomb formation in circular orbits and at libration points; it addresses relative equilibria, stability and optimal reconfigurations of such formations. The relative equilibria of a two-craft tether formation connected by line-of-sight elastic forces moving in circular orbits and at libration points are investigated. In circular Earth orbits and Earth-Moon libration points, the radial, along-track, and orbit normal great circle equilibria conditions are found. An example of modeling the tether force using Coulomb force is discussed. Furthermore, the non-great-circle equilibria conditions for a two-spacecraft tether structure in circular Earth orbit and at collinear libration points are developed. Then the linearized dynamics and stability analysis of a 2-craft Coulomb formation at Earth-Moon libration points are studied. For orbit-radial equilibrium, Coulomb forces control the relative distance between the two satellites. The gravity gradient torques on the formation due to the two planets help stabilize the formation. Similar analysis is performed for along-track and orbit-normal relative equilibrium configurations. Where necessary, the craft use a hybrid thrusting-electrostatic actuation system. The two-craft dynamics at the libration points provide a general framework with circular Earth orbit dynamics forming a special case. In the presence of differential solar drag perturbations, a Lyapunov feedback controller is designed to stabilize a radial equilibrium, two-craft Coulomb formation at collinear libration points. The second part of the thesis investigates optimal reconfigurations of two-craft Coulomb formations in circular Earth orbits by applying nonlinear optimal control techniques. The objective of these reconfigurations is to maneuver the two-craft formation between two charged equilibria configurations. The reconfiguration of spacecraft is posed as an optimization problem using the

ESOC activities during the MIR de-orbit

Science.gov (United States)

Klinkrad, H.; Flury, W.; Hernández, C.; Landgraf, M.; Jehn, R.; Christ, U.; Sintoni, F.

2002-11-01

On March 23, 2001, MIR was de-orbited in a controlled fashion, following a successful mission of 15 years. The de-orbiting operations were conducted by the TsUP Mission Control Center, who also consulted entities outside Russia, in order to consolidate their knowledge on the MIR orbit and attitude prior to the initiation of the de-orbit sequence. The European Space Agency ESA through their operations centre ESOC was tasked to support the pre-entry analysis of TsUP by own results, and by routing of Russian and European data via a dedicated communications network. Analysis results produced by ESOC, and details on the data exchange will be highlighted in this paper. The MIR de-orbit and its assessed risk potential will also be compared with the re-entries of Skylab and Salyut-7/Kosmos-1686.

Guidance system operations plan for manned cm earth orbital and lunar missions using program Colossus 3. Section 2: Data links

Science.gov (United States)

Hamilton, M. H.

1971-01-01

The data links for use with the guidance system operations plan for manned command module earth orbital and lunar missions using program Colossus 3 are presented. The subjects discussed are: (1) digital uplink to CMC, (2) command module contiguous block update, (3) CMC retrofire external data update, (4) CMC digital downlink, and (5) CMC entry update.

Maintaining Aura's Orbit Requirements While Performing Orbit Maintenance Maneuvers Containing an Orbit Normal Delta-V Component

Science.gov (United States)

Johnson, Megan R.; Petersen, Jeremy D.

2014-01-01

The Earth Observing System (EOS) Afternoon Constellation consists of five member missions (GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura), each of which maintain a frozen, sun-synchronous orbit with a 16-day repeating ground track that follows the Worldwide Reference System-2 (WRS-2). Under nominal science operations for Aura, the propulsion system is oriented such that the resultant thrust vector is aligned 13.493 degrees away from the velocity vector along the yaw axis. When performing orbit maintenance maneuvers, the spacecraft performs a yaw slew to align the thrust vector in the appropriate direction. A new Drag Make Up (DMU) maneuver operations scheme has been implemented for Aura alleviating the need for the 13.493 degree yaw slew. The focus of this investigation is to assess the impact that no-slew DMU maneuver operations will have on Aura's Mean Local Time (MLT) which drives the required along track separation between Aura and the constellation members, as well as Aura's frozen orbit properties, eccentricity and argument of perigee. Seven maneuver strategies were analyzed to determine the best operational approach. A mirror pole strategy, with maneuvers alternating at the North and South poles, was implemented operationally to minimize impact to the MLT. Additional analysis determined that the mirror pole strategy could be further modified to include frozen orbit maneuvers and thus maintain both MLT and the frozen orbit properties under noslew operations.

Orbit Display's Use of the Physics Application Framework

International Nuclear Information System (INIS)

Zelazny, Michael

2009-01-01

At the SLAC National Accelerator Laboratory (SLAC) the Controls Department (CD) is developing a physics application framework based on the Java(tm) programming language developed by Sun Microsystems. This paper will discuss the first application developed using this approach: a new Orbit Display. The software is being developed by several individuals in reusable Java packages. It relies on the Experimental Physics and Industrial Control System (EPICS) toolkit for data collection and XAL - A Java based Hierarchy for Application Programming for model parameters. The Orbit Display tracks and displays electron paths through the Linac Coherent Light Source (LCLS) in both a graphical, beam line plot, and tabular format. It contains many features that may be unique to SLAC and is meant to be used both in the control room and by individuals in their offices or at home. Unique features include BSA Beam Synchronous Acquisition (BSA), Orbit Fitting, and Buffered Acquisition.

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

Science.gov (United States)

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

Post-operative cyst and orbital walls. A CT image analysis

Energy Technology Data Exchange (ETDEWEB)

Fukuta, Masahiro (Takeda General Hospital, Aizuwakamatsu, Fukushima (Japan)); Iinuma, Toshitaka

1989-07-01

A set of coronal CT images obtained by 118 sides (109 cases) of post-operative cysts of maxilla, seen from 1982 to 1988, was analyzed as to the orbital wall affections. Coronal images were grouped into five consecutive planes, i.e. the first plane being the one which is 5 mm posterior to the nasion, and the other planes in successive orders each being 5 mm apart. The orbital walls were classified into inferior, medial, and transition of these two. The orbital wall affections were classified into dehiscence, thinned-out (less than 1 mm), and normal. The orbital signs and symptoms (epiphora, pain, asthenopia, visual loss, diplopia, and exophthalmos) were analyzed based upon the questionnaires by patients. The inferior wall affections (dehiscence and thinned-out) were seen most often (57%) at the third plane (2 cm posterior to the nasion). The orbital signs and symptoms in general were seen in half of the cases of which 20% were of grave (visual loss, diplopia and exophthalmos). These signs and symptoms were the more often, the more anterior the site of affections located. Grave signs and symptoms were seen at 2 to 2.5 cm posterior to the nasion when the orbital floor was affected and the inferior rectus were either pushed up or in direct contact with the cysts. (author).

Influence of the Choice of Lunar Gravity Model on Orbit Determination for Lunar Orbiters

Directory of Open Access Journals (Sweden)

Young-Rok Kim

2018-01-01

Full Text Available We examine the influence of the lunar gravity model on the orbit determination (OD of a lunar orbiter operating in a 100 km high, lunar polar orbit. Doppler and sequential range measurements by three Deep Space Network antennas and one Korea Deep Space Antenna were used. For measurement simulation and OD analysis, STK11 and ODTK6 were utilized. GLGM2, LP100K, LP150Q, GRAIL420A, and GRAIL660B were used for investigation of lunar gravity model selection effect. OD results were assessed by position and velocity uncertainties with error covariance and an external orbit comparison using simulated true orbit. The effect of the lunar gravity models on the long-term OD, degree and order level, measurement-acquisition condition, and lunar altitude was investigated. For efficiency verification, computational times for the five lunar gravity models were compared. Results showed that significant improvements to OD accuracy are observed by applying a GRAIL-based model; however, applying a full order and degree gravity modeling is not always the best strategy, owing to the computational burden. Consequently, we consider that OD using GRAIL660B with 70 × 70 degree and order is the most efficient strategy for mission preanalysis. This study provides useful guideline for KPLO OD analysis during nominal mission operation.

Effect of orbital symmetry on the anisotropic superexchange interaction

International Nuclear Information System (INIS)

Kim, Beom Hyun; Min, B I

2011-01-01

Employing the microscopic superexchange model incorporating the effect of spin-orbit interaction, we have investigated the Dzyaloshinsky-Moriya (DM) interaction in perovskite transition-metal (TM) oxides and explored the interplay between the DM interaction and the TM-3d orbital symmetry. For d 3 and d 5 systems with isotropic orbital symmetry, the DM vectors are well described by a simple symmetry analysis considering only the bond geometry. In contrast, the DM interaction for d 4 systems with anisotropic orbital symmetry shows slightly different behavior, which does not obey simple symmetry analysis. The direction as well as the strength of the DM vector varies depending on the occupied orbital shape. We have understood this behavior based on the orbital symmetry induced by local crystal field variation.

Space Shuttle Program (SSP) Orbiter Main Propulsion System (MPS) Gaseous Hydrogen (GH2) Flow Control Valve (FCV) Poppet Eddy Current (EC) Inspection Probability of Detection (POD) Study. Volume 1

Science.gov (United States)

Piascik, Robert S.; Prosser, William H.

2011-01-01

The Director of the NASA Engineering and Safety Center (NESC), requested an independent assessment of the anomalous gaseous hydrogen (GH2) flow incident on the Space Shuttle Program (SSP) Orbiter Vehicle (OV)-105 during the Space Transportation System (STS)-126 mission. The main propulsion system (MPS) engine #2 GH2 flow control valve (FCV) LV-57 transition from low towards high flow position without being commanded. Post-flight examination revealed that the FCV LV-57 poppet had experienced a fatigue failure that liberated a section of the poppet flange. The NESC assessment provided a peer review of the computational fluid dynamics (CFD), stress analysis, and impact testing. A probability of detection (POD) study was requested by the SSP Orbiter Project for the eddy current (EC) nondestructive evaluation (NDE) techniques that were developed to inspect the flight FCV poppets. This report contains the findings and recommendations from the NESC assessment.

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

Science.gov (United States)

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

Shape of the orbital opening: individual characterization and analysis of variability in modern humans, Gorilla gorilla, and Pan troglodytes.

Science.gov (United States)

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.

Correlation between the 2-Dimensional Extent of Orbital Defects and the 3-Dimensional Volume of Herniated Orbital Content in Patients with Isolated Orbital Wall Fractures

Directory of Open Access Journals (Sweden)

Jong Hyun Cha

2017-01-01

Full Text Available BackgroundThe purpose of this study was to assess the correlation between the 2-dimensional (2D extent of orbital defects and the 3-dimensional (3D volume of herniated orbital content in patients with an orbital wall fracture.MethodsThis retrospective study was based on the medical records and radiologic data of 60 patients from January 2014 to June 2016 for a unilateral isolated orbital wall fracture. They were classified into 2 groups depending on whether the fracture involved the inferior wall (group I, n=30 or the medial wall (group M, n=30. The 2D area of the orbital defect was calculated using the conventional formula. The 2D extent of the orbital defect and the 3D volume of herniated orbital content were measured with 3D image processing software. Statistical analysis was performed to evaluate the correlations between the 2D and 3D parameters.ResultsVarying degrees of positive correlation were found between the 2D extent of the orbital defects and the 3D herniated orbital volume in both groups (Pearson correlation coefficient, 0.568−0.788; R2=32.2%−62.1%.ConclusionsBoth the calculated and measured 2D extent of the orbital defects showed a positive correlation with the 3D herniated orbital volume in orbital wall fractures. However, a relatively large volume of herniation (>0.9 cm3 occurred not infrequently despite the presence of a small orbital defect (<1.9 cm2. Therefore, estimating the 3D volume of the herniated content in addition to the 2D orbital defect would be helpful for determining whether surgery is indicated and ensuring adequate surgical outcomes.

Precise Orbital and Geodetic Parameter Estimation using SLR Observations for ILRS AAC

Directory of Open Access Journals (Sweden)

Young-Rok Kim

2013-12-01

Full Text Available In this study, we present results of precise orbital geodetic parameter estimation using satellite laser ranging (SLR observations for the International Laser Ranging Service (ILRS associate analysis center (AAC. Using normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 in SLR consolidated laser ranging data format, the NASA/ GSFC GEODYN II and SOLVE software programs were utilized for precise orbit determination (POD and finding solutions of a terrestrial reference frame (TRF and Earth orientation parameters (EOPs. For POD, a weekly-based orbit determination strategy was employed to process SLR observations taken from 20 weeks in 2013. For solutions of TRF and EOPs, loosely constrained scheme was used to integrate POD results of four geodetic SLR satellites. The coordinates of 11 ILRS core sites were determined and daily polar motion and polar motion rates were estimated. The root mean square (RMS value of post-fit residuals was used for orbit quality assessment, and both the stability of TRF and the precision of EOPs by external comparison were analyzed for verification of our solutions. Results of post-fit residuals show that the RMS of the orbits of LAGEOS-1 and LAGEOS-2 are 1.20 and 1.12 cm, and those of ETALON-1 and ETALON-2 are 1.02 and 1.11 cm, respectively. The stability analysis of TRF shows that the mean value of 3D stability of the coordinates of 11 ILRS core sites is 7.0 mm. An external comparison, with respect to International Earth rotation and Reference systems Service (IERS 08 C04 results, shows that standard deviations of polar motion Xp and Yp are 0.754 milliarcseconds (mas and 0.576 mas, respectively. Our results of precise orbital and geodetic parameter estimation are reasonable and help advance research at ILRS AAC.

Guidance system operations plan for manned LM earth orbital and lunar missions using program luminary 1E. Section 2: Data links

Science.gov (United States)

Hamilton, M. H.

1972-01-01

Data links for the guidance system of manned lunar module orbital and lunar missions are presented. Subjects discussed are: (1) digital uplink to lunar module, (2) lunar module liftoff time increment, (3) lunar module contiguous block update, (4) lunar module scatter update, (5) lunar module digital downlink, and (6) absolute addresses for update program.

Large orbit neoclassical transport

International Nuclear Information System (INIS)

Lin, Z.; Tang, W.M.; Lee, W.W.

1997-01-01

Neoclassical transport in the presence of large ion orbits is investigated. The study is motivated by the recent experimental results that ion thermal transport levels in enhanced confinement tokamak plasmas fall below the open-quotes irreducible minimum levelclose quotes predicted by standard neoclassical theory. This apparent contradiction is resolved in the present analysis by relaxing the basic neoclassical assumption that the ions orbital excursions are much smaller than the local toroidal minor radius and the equilibrium scale lengths of the system. Analytical and simulation results are in agreement with trends from experiments. The development of a general formalism for neoclassical transport theory with finite orbit width is also discussed. copyright 1997 American Institute of Physics

Ongoing Recovery Basic Information Tool (ORBIT)

Science.gov (United States)

Oberg, Donald

1993-01-01

The Federal Drug Free Work Place Program (DFWP) has now matured to the point of being able to return employees to sensitive testing designated positions (TDP) after completion of treatment of their addiction. The known tendency of addicted individuals to suffer multiple relapses prior to their final recovery has resulted in several positive urine tests (relapses) occurring among those Federal employees who have already completed treatment and who have been returned to TDP's. The very real potential for further relapses occurring after additional employees return to TDP's will be a critical factor in the ultimate success of the DFWP and in the public's impression of the program's effectiveness. In response to this concern, NASA has begun development of its Ongoing Recovery Basic Information Tool (ORBIT) instrument. The aim of the NASA ORBIT is to provide Employee Assistance Program (EAP) professionals with an advanced clinical tool which will be helpful in supporting recovery from substance abuse and which will allow more accurate determinations of when clients may be successfully returned to sensitive positions.

LULU analysis program

International Nuclear Information System (INIS)

Crawford, H.J.; Lindstrom, P.J.

1983-06-01

Our analysis program LULU has proven very useful in all stages of experiment analysis, from prerun detector debugging through final data reduction. It has solved our problem of having arbitrary word length events and is easy enough to use that many separate experimenters are now analyzing with LULU. The ability to use the same software for all stages of experiment analysis greatly eases the programming burden. We may even get around to making the graphics elegant someday

Generating precise and homogeneous orbits for Jason-1 and Jason-2

Science.gov (United States)

Flohrer, Claudia; Otten, Michiel; Springer, Tim; Dow, John M.

Driven by the GMES (Global Monitoring for Environment and Security) and GGOS (Global Geodetic Observing System) initiatives the user community has a strong demand for high-quality altimetry products. In order to derive such high-quality altimetry products, precise orbits for the altimetry satellites are needed. Satellite altimetry missions meanwhile span over three decades, in which our understanding of the Earth has increased significantly. As also the models used for precise orbit determination (POD) have improved, the satellite orbits of the altimetry satellites are not available in an uniform reference system. Homogeneously determined orbits referring to the same global reference system are, however, needed to improve our understanding of the Earth system. With the launch of the TOPEX/Poseidon (T/P) mission in 1992 a still ongoing time series of high-altimetry measurements of ocean topography started. In 2001 the altimetry mission Jason-1 took over and in 2009 the follow-on program Jason-2/OSTM started. All three satellites follow the same ground-track by flying in the same orbit, thus ensuring a continuous time-series of centimetre-level ocean topography observations. Therefore a reprocessing of the orbit determination for these altimetry satellites would be highly beneficial for altimetry applications. The Navigation Support Office at ESA/ESOC has enhanced the GNSS processing capabilities of its NAPEOS software. Thus it is now in the unique position to do orbit determination by combining different types of data, and by using one single software system for different satellite types, including the most recent improvements in orbit and observation modelling and IERS conventions. Our presentation focuses on the re-processing efforts carried out by ESA/ESOC for the gener-ation of precise and homogeneous orbits referring to the same reference frame for the altimetry satellites Jason-1 and Jason-2. At the same time ESOC carried out a re-processing of the com

Analysis of the SPS Long Term Orbit Drifts

Energy Technology Data Exchange (ETDEWEB)

Velotti, Francesco [CERN; Bracco, Chiara [CERN; Cornelis, Karel [CERN; Drøsdal, Lene [CERN; Fraser, Matthew [CERN; Gianfelice-Wendt, Eliana [Fermilab; Goddard, Brennan [CERN; Kain, Verena [CERN; Meddahi, Malika [CERN

2016-06-01

The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain, and has to deliver the two high-intensity 450 GeV proton beams to the LHC. The transport from SPS to LHC is done through the two Transfer Lines (TL), TI2 and TI8, for Beam 1 (B1) and Beam 2 (B2) respectively. During the first LHC operation period Run 1, a long term drift of the SPS orbit was observed, causing changes in the LHC injection due to the resulting changes in the TL trajectories. This translated into longer LHC turnaround because of the necessity to periodically correct the TL trajectories in order to preserve the beam quality at injection into the LHC. Different sources for the SPS orbit drifts have been investigated: each of them can account only partially for the total orbit drift observed. In this paper, the possible sources of such drift are described, together with the simulated and measured effect they cause. Possible solutions and countermeasures are also discussed.

Determination of Orbiter and Carrier Aerodynamic Coefficients from Load Cell Measurements

Science.gov (United States)

Glenn, G. M.

1976-01-01

A method of determining orbiter and carrier total aerodynamic coefficients from load cell measurements is required to support the inert and the captive active flights of the ALT program. A set of equations expressing the orbiter and carrier total aerodynamic coefficients in terms of the load cell measurements, the sensed dynamics of the Boeing 747 (carrier) aircraft, and the relative geometry of the orbiter/carrier is derived.

Study of orbit stability in the SSRF storage ring

International Nuclear Information System (INIS)

Dai Zhimin; Liu Guimin; Huang Nan

2003-01-01

In this paper, analysis of the beam orbit stability and conceptual study of the dynamic orbit feedback in the SSRF storage ring are presented. It is shown that beam orbit position movement at the photon source points is smaller than the orbit stability requirements in horizontal plane, but exceeds the orbit stability requirements in vertical plane. A dynamic global orbit feedback system, which consists of 38 high-bandwidth air-coil correctors and 40 high-precise BPMs, is proposed to suppress the vertical beam orbit position movement. Numerical simulations show that this dynamic orbit feedback system can stabilize the vertical beam orbit position movement in the frequency range up to 100 Hz

Linear Magnetoelectric Effect by Orbital Magnetism

NARCIS (Netherlands)

Scaramucci, A.; Bousquet, E.; Fechner, M.; Mostovoy, M.; Spaldin, N. A.

2012-01-01

We use symmetry analysis and first-principles calculations to show that the linear magnetoelectric effect can originate from the response of orbital magnetic moments to the polar distortions induced by an applied electric field. Using LiFePO4 as a model compound we show that spin-orbit coupling

A Program Transformation for Backwards Analysis of Logic Programs

DEFF Research Database (Denmark)

Gallagher, John Patrick

2003-01-01

The input to backwards analysis is a program together with properties that are required to hold at given program points. The purpose of the analysis is to derive initial goals or pre-conditions that guarantee that, when the program is executed, the given properties hold. The solution for logic...... programs presented here is based on a transformation of the input program, which makes explicit the dependencies of the given program points on the initial goals. The transformation is derived from the resultants semantics of logic programs. The transformed program is then analysed using a standard...

A Method for Calculating the Mean Orbits of Meteor Streams

Science.gov (United States)

Voloshchuk, Yu. I.; Kashcheev, B. L.

An examination of the published catalogs of orbits of meteor streams and of a large number of works devoted to the selection of streams, their analysis and interpretation, showed that elements of stream orbits are calculated, as a rule, as arithmetical (sometimes, weighed) sample means. On the basis of these means, a search for parent bodies, a study of the evolution of swarms generating these streams, an analysis of one-dimensional and multidimensional distributions of these elements, etc., are performed. We show that systematic errors in the estimates of elements of the mean orbits are present in each of the catalogs. These errors are caused by the formal averaging of orbital elements over the sample, while ignoring the fact that they represent not only correlated, but dependent quantities, with nonlinear, in most cases, interrelations between them. Numerous examples are given of such inaccuracies, in particular, the cases where the "mean orbit of the stream" recorded by ground-based techniques does not cross the Earth's orbit. We suggest the computation algorithm, in which the averaging over the sample is carried out at the initial stage of the calculation of the mean orbit, and only for the variables required for subsequent calculations. After this, the known astrometric formulas are used to sequentially calculate all other parameters of the stream, considered now as a standard orbit. Variance analysis is used to estimate the errors in orbital elements of the streams, in the case that their orbits are obtained by averaging the orbital elements of meteoroids forming the stream, without taking into account their interdependence. The results obtained in this analysis indicate the behavior of systematic errors in the elements of orbits of meteor streams. As an example, the effect of the incorrect computation method on the distribution of elements of the stream orbits close to the orbits of asteroids of the Apollo, Aten, and Amor groups (AAA asteroids) is examined.

Space Shuttle Program (SSP) Orbiter Main Propulsion System (MPS) Gaseous Hydrogen (GH2) Flow Control Valve (FCV) Poppet Eddy Current (EC) Inspection Probability of Detection (POD) Study. Volume 2; Appendices

Science.gov (United States)

Piascik, Robert S.; Prosser, William H.

2011-01-01

The Director of the NASA Engineering and Safety Center (NESC), requested an independent assessment of the anomalous gaseous hydrogen (GH2) flow incident on the Space Shuttle Program (SSP) Orbiter Vehicle (OV)-105 during the Space Transportation System (STS)-126 mission. The main propulsion system (MPS) engine #2 GH2 flow control valve (FCV) LV-57 transition from low towards high flow position without being commanded. Post-flight examination revealed that the FCV LV-57 poppet had experienced a fatigue failure that liberated a section of the poppet flange. The NESC assessment provided a peer review of the computational fluid dynamics (CFD), stress analysis, and impact testing. A probability of detection (POD) study was requested by the SSP Orbiter Project for the eddy current (EC) nondestructive evaluation (NDE) techniques that were developed to inspect the flight FCV poppets. This report contains the Appendices to the main report.

Apollo guidance, navigation and control: Guidance system operations plan for manned CM earth orbital and lunar missions using Program COLOSSUS 3. Section 3: Digital autopilots (revision 14)

Science.gov (United States)

1972-01-01

Digital autopilots for the manned command module earth orbital and lunar missions using program COLOSSUS 3 are discussed. Subjects presented are: (1) reaction control system digital autopilot, (2) thrust vector control autopilot, (3) entry autopilot and mission control programs, (4) takeover of Saturn steering, and (5) coasting flight attitude maneuver routine.

Characterizing the Survey Strategy and Initial Orbit Determination Abilities of the NASA MCAT Telescope for Geosynchronous Orbital Debris Environmental Studies

Science.gov (United States)

Frith, J.; Barker, E.; Cowardin, H.; Buckalew, B.; Anz-Meador, P.; Lederer, S.

The National Aeronautics and Space Administration (NASA) Orbital Debris Program Office (ODPO) recently commissioned the Meter Class Autonomous Telescope (MCAT) on Ascension Island with the primary goal of obtaining population statistics of the geosynchronous (GEO) orbital debris environment. To help facilitate this, studies have been conducted using MCAT’s known and projected capabilities to estimate the accuracy and timeliness in which it can survey the GEO environment, including collected weather data and the proposed observational data collection cadence. To optimize observing cadences and probability of detection, on-going work using a simulated GEO debris population sampled at various cadences are run through the Constrained Admissible Region Multi Hypotheses Filter (CAR-MHF). The orbits computed from the results are then compared to the simulated data to assess MCAT’s ability to determine accurately the orbits of debris at various sample rates. The goal of this work is to discriminate GEO and near-GEO objects from GEO transfer orbit objects that can appear as GEO objects in the environmental models due to the short arc observation and an assumed circular orbit. The specific methods and results are presented here.

Review of current activities to model and measure the orbital debris environment in low-earth orbit

Science.gov (United States)

Reynolds, R. C.

A very active orbital debris program is currently being pursued at the NASA/Johnson Space Center (JSC), with projects designed to better define the current environment, to project future environments, to model the processes contributing to or constraining the growth of debris in the environment, and to gather supporting data needed to improve the understanding of the orbital debris problem and the hazard it presents to spacecraft. This paper is a review of the activity being conducted at JSC, by NASA, Lockheed Engineering and Sciences Company, and other support contractors, and presents a review of current activity, results of current research, and a discussion of directions for future development.

Single-stage-to-orbit: Meeting the challenge

Science.gov (United States)

Freeman, Delma C., Jr.; Talay, Theodore A.; Austin, Robert Eugene

1995-10-01

There has been and continues to be significant discussion about the viability of fully reusable, single-stage-to-orbit (SSTO) concepts for delivery of payloads to orbit. Often, these discussions have focused in detail on performance and technology requirements relating to the technical feasibility of the concept, with only broad generalizations on how the SSTO will achieve its economic goals of greatly reduced vehicle ground and flight operations costs. With the current industry and NASA Reusable Launch Vehicle Technology Program efforts underway to mature and demonstrate technologies leading to a viable commercial launch system that also satisfies national needs, achieving acceptable recurring costs becomes a significant challenge. This paper reviews the current status of the Reusable Launch Vehicle Technology Program including the DC-XA, X-33, and X-34 flight systems and associated technology programs. The paper also examines lessons learned from the recently completed DC-X reusable rocket demonstrator program. It examines how these technologies and flight systems address the technical and operability challenges of SSTO whose solutions are necessary to reduce costs. The paper also discusses the management and operational approaches that address the challenge of a new cost-effective, reusable launch vehicle system.

Liquid Effluents Program mission analysis

International Nuclear Information System (INIS)

Lowe, S.S.

1994-01-01

Systems engineering is being used to identify work to cleanup the Hanford Site. The systems engineering process transforms an identified mission need into a set of performance parameters and a preferred system configuration. Mission analysis is the first step in the process. Mission analysis supports early decision-making by clearly defining the program objectives, and evaluating the feasibility and risks associated with achieving those objectives. The results of the mission analysis provide a consistent basis for subsequent systems engineering work. A mission analysis was performed earlier for the overall Hanford Site. This work was continued by a ''capstone'' team which developed a top-level functional analysis. Continuing in a top-down manner, systems engineering is now being applied at the program and project levels. A mission analysis was conducted for the Liquid Effluents Program. The results are described herein. This report identifies the initial conditions and acceptable final conditions, defines the programmatic and physical interfaces and sources of constraints, estimates the resources to carry out the mission, and establishes measures of success. The mission analysis reflects current program planning for the Liquid Effluents Program as described in Liquid Effluents FY 1995 Multi-Year Program Plan

Analysis of radiation damage in on-orbit solar array of Venus explorer Akatsuki

International Nuclear Information System (INIS)

Toyota, Hiroyuki; Shimada, Takanobu; Takahashi, You; Imamura, Takeshi; Hada, Yuko; Ishii, Takako T.; Isobe, Hiroaki; Asai, Ayumi; Shiota, Daikou

2013-01-01

This paper describes an analysis of radiation damage in solar array of Venus explorer Akatsuki observed on orbit. The output voltage of the solar array have shown sudden drops, which are most reasonably associated with radiation damage, three times since its launch. The analysis of these radiation damages is difficult, because no direct observation data of the spectra and the amount of the high-energy particles is available. We calculated the radiation damage using the relative damage coefficient (RDC) method assuming a typical spectral shape of protons. (author)

International patent analysis of water source heat pump based on orbit database

Science.gov (United States)

Li, Na

2018-02-01

Using orbit database, this paper analysed the international patents of water source heat pump (WSHP) industry with patent analysis methods such as analysis of publication tendency, geographical distribution, technology leaders and top assignees. It is found that the beginning of the 21st century is a period of rapid growth of the patent application of WSHP. Germany and the United States had done researches and development of WSHP in an early time, but now Japan and China have become important countries of patent applications. China has been developing faster and faster in recent years, but the patents are concentrated in universities and urgent to be transferred. Through an objective analysis, this paper aims to provide appropriate decision references for the development of domestic WSHP industry.

Inspection of the Math Model Tools for On-Orbit Assessment of Impact Damage Report. Version 1.0

Science.gov (United States)

Harris, Charles E.; Raju, Ivatury S.; Piascik, Robert S.; Kramer White, Julie; Labbe, Steve G.; Rotter, Hank A.

2005-01-01

In Spring of 2005, the NASA Engineering Safety Center (NESC) was engaged by the Space Shuttle Program (SSP) to peer review the suite of analytical tools being developed to support the determination of impact and damage tolerance of the Orbiter Thermal Protection Systems (TPS). The NESC formed an independent review team with the core disciplines of materials, flight sciences, structures, mechanical analysis and thermal analysis. The Math Model Tools reviewed included damage prediction and stress analysis, aeroheating analysis, and thermal analysis tools. Some tools are physics-based and other tools are empirically-derived. Each tool was created for a specific use and timeframe, including certification, real-time pre-launch assessments, and real-time on-orbit assessments. The tools are used together in an integrated strategy for assessing the ramifications of impact damage to tile and RCC. The NESC teams conducted a peer review of the engineering data package for each Math Model Tool. This report contains the summary of the team observations and recommendations from these reviews.

Getting a Crew into Orbit

Science.gov (United States)

Riddle, Bob

2011-01-01

Despite the temporary setback in our country's crewed space exploration program, there will continue to be missions requiring crews to orbit Earth and beyond. Under the NASA Authorization Act of 2010, NASA should have its own heavy launch rocket and crew vehicle developed by 2016. Private companies will continue to explore space, as well. At the…

Preliminary radar systems analysis for Venus orbiter missions

Science.gov (United States)

Brandenburg, R. K.; Spadoni, D. J.

1971-01-01

A short, preliminary analysis is presented of the problems involved in mapping the surface of Venus with radar from an orbiting spacecraft. Two types of radar, the noncoherent sidelooking and the focused synthetic aperture systems, are sized to fulfill two assumed levels of Venus exploration. The two exploration levels, regional and local, assumed for this study are based on previous Astro Sciences work (Klopp 1969). The regional level is defined as 1 to 3 kilometer spatial and 0.5 to 1 km vertical resolution of 100 percent 0 of the planet's surface. The local level is defined as 100 to 200 meter spatial and 50-10 m vertical resolution of about 100 percent of the surfAce (based on the regional survey). A 10cm operating frequency was chosen for both radar systems in order to minimize the antenna size and maximize the apparent radar cross section of the surface.

Characterizing the Survey Strategy and Initial Orbit Determination Abilities of the NASA MCAT Telescope for Geosynchronous Orbital Debris Environmental Studies

Science.gov (United States)

Frith, James; Barker, Ed; Cowardin, Heather; Buckalew, Brent; Anz-Meado, Phillip; Lederer, Susan

2017-01-01

The NASA Orbital Debris Program Office (ODPO) recently commissioned the Meter Class Autonomous Telescope (MCAT) on Ascension Island with the primary goal of obtaining population statistics of the geosynchronous (GEO) orbital debris environment. To help facilitate this, studies have been conducted using MCAT's known and projected capabilities to estimate the accuracy and timeliness in which it can survey the GEO environment. A simulated GEO debris population is created and sampled at various cadences and run through the Constrained Admissible Region Multi Hypotheses Filter (CAR-MHF). The orbits computed from the results are then compared to the simulated data to assess MCAT's ability to determine accurately the orbits of debris at various sample rates. Additionally, estimates of the rate at which MCAT will be able produce a complete GEO survey are presented using collected weather data and the proposed observation data collection cadence. The specific methods and results are presented here.

The Laser Ranging Experiment of the Lunar Reconnaissance Orbiter: Five Years of Operations and Data Analysis

Science.gov (United States)

Mao, Dandan; McGarry, Jan F.; Mazarico, Erwan; Neumann, Gregory A.; Sun, Xiaoli; Torrence, Mark H.; Zagwodzki, Thomas W.; Rowlands, David D.; Hoffman, Evan D.; Horvath, Julie E.;

Applicability of meteor radiant determination methods depending on orbit type. I. High-eccentric orbits

Science.gov (United States)

Svoren, J.; Neslusan, L.; Porubcan, V.

1993-07-01

It is evident that there is no uniform method of calculating meteor radiants which would yield reliable results for all types of cometary orbits. In the present paper an analysis of this problem is presented, together with recommended methods for various types of orbits. 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, we applied the Southworth-Hawkins D-criterion (Southworth, R.B., Hawkins, G.S.: 1963, Smithson. Contr. Astrophys 7, 261). D0.2 the fit is rather poor and the change of orbit unrealistic. The optimal methods with the smallest values of D for given types of orbits are shown in two series of six plots. The new method of rotation around the line of apsides we propose is very appropriate in the region of small inclinations. There is no doubt that Hasegawa's omega-adjustment method (Hasegawa, I.: 1990, Publ. Astron. Soc. Japan 42, 175) has the widest application. A comparison of the theoretical radiants with the observed radiants of seven known meteor showers is also presented.

Genetic analysis of an orbital metastasis from a primary hepatic neuroendocrine carcinoma

DEFF Research Database (Denmark)

Rasmussen, Jacob Ø; von Holstein, Sarah L; Prause, Jan U

2014-01-01

and immunohistochemical features, and high-resolution, array-based comparative genomic hybridization demonstrated loss of one copy each of chromosomes 3 and 18, and gain of 1q both in the primary hepatic neuroendocrine carcinoma and in the orbital tumour. The orbital mass was diagnosed as a metastasis from the primary...... hepatic neuroendocrine carcinoma. Primary hepatic neuroendocrine tumours are extremely rare, and the orbit is an extremely rare location for a neuroendocrine carcinoma metastasis. This is the first reported case of an orbital metastasis with origin from a primary hepatic neuroendocrine carcinoma....

Mean Orbital Elements for Geosynchronous Orbit - II - Orbital inclination, longitude of ascending node, mean longitude

Directory of Open Access Journals (Sweden)

Kyu-Hong Choi

1990-06-01

Full Text Available The osculating orbital elements include the mean, secular, long period, and short period terms. The iterative algorithm used for conversion of osculating orbital elements to mean orbital elements is described. The mean orbital elements of Wc, Ws, and L are obtained.

Orbital Debris: Past, Present, and Future

Science.gov (United States)

Stansbery, Gene; Johnson, Nicholas

2013-01-01

In the early days of spaceflight, the gBig Sky h theory was the near universally accepted paradigm for dealing with collisions of orbiting objects. This theory was also used during the early years of the aviation industry. Just as it did in aviation, the gBig Sky h theory breaks down as more and more objects accumulate in the environment. Fortunately, by the late 1970 fs some visionaries in NASA and the US Department of Defense (DoD) realized that trends in the orbital environment would inevitably lead to increased risks to operational spacecraft from collisions with other orbiting objects. The NASA Orbital Debris Program was established at and has been conducted at Johnson Space Center since 1979. At the start of 1979, fewer than 5000 objects were being tracked by the US Space Surveillance Network and very few attempts had been made to sample the environment for smaller sizes. Today, the number of tracked objects has quadrupled. Ground ]based and in situ measurements have statistically sampled the LEO environment over most sizes and mitigation guidelines and requirements are common among most space faring nations. NASA has been a leader, not only in defining the debris environment, but in promoting awareness of the issues in the US and internationally, and in providing leadership in developing policies to address the issue. This paper will discuss in broad terms the evolution of the NASA debris program from its beginnings to its present broad range of debris related research. The paper will discuss in some detail current research topics and will attempt to predict future research trends.

Lessons Learned for Cx PRACA. Constellation Program Problem Reporting, Analysis and Corrective Action Process and System

Science.gov (United States)

Kelle, Pido I.; Ratterman, Christian; Gibbs, Cecil

2009-01-01

This slide presentation reviews the Constellation Program Problem Reporting, Analysis and Corrective Action Process and System (Cx PRACA). The goal of the Cx PRACA is to incorporate Lessons learned from the Shuttle, ISS, and Orbiter programs by creating a single tool for managing the PRACA process, that clearly defines the scope of PRACA applicability and what must be reported, and defines the ownership and responsibility for managing the PRACA process including disposition approval authority. CxP PRACA is a process, supported by a single information gathering data module which will be integrated with a single CxP Information System, providing interoperability, import and export capability making the CxP PRACA a more effective and user friendly technical and management tool.

Outward Migration of Giant Planets in Orbital Resonance

Science.gov (United States)

D'Angelo, G.; Marzari, F.

2013-05-01

A pair of giant planets interacting with a gaseous disk may be subject to convergent orbital migration and become locked into a mean motion resonance. If the orbits are close enough, the tidal gaps produced by the planets in the disk may overlap. This represents a necessary condition to activate the outward migration of the pair. However, a number of other conditions must also be realized in order for this mechanism to operate. We have studied how disk properties, such as turbulence viscosity, temperature, surface density gradient, mass, and age, may affect the outcome of the outward migration process. We have also investigated the implications on this mechanism of the planets' gas accretion. If the pair resembles Jupiter and Saturn, the 3:2 orbital resonance may drive them outward until they reach stalling radii for migration, which are within ~10 AU of the star for disks representative of the early proto-solar nebula. However, planet post-formation conditions in the disk indicate that such planets become typically locked in the 1:2 orbital resonance, which does not lead to outward migration. Planet growth via gas accretion tends to alter the planets' mass-ratio and/or the disk accretion rate toward the star, reducing or inhibiting outward migration. Support from NASA Outer Planets Research Program and NASA Origins of Solar Systems Program is gratefully acknowledged.

[Orbital inflammation].

Science.gov (United States)

Mouriaux, F; Coffin-Pichonnet, S; Robert, P-Y; Abad, S; Martin-Silva, N

2014-12-01

Orbital inflammation is a generic term encompassing inflammatory pathologies affecting all structures within the orbit : anterior (involvement up to the posterior aspect of the globe), diffuse (involvement of intra- and/or extraconal fat), apical (involvement of the posterior orbit), myositis (involvement of only the extraocular muscles), dacryoadenitis (involvement of the lacrimal gland). We distinguish between specific inflammation and non-specific inflammation, commonly referred to as idiopathic inflammation. Specific orbital inflammation corresponds to a secondary localization of a "generalized" disease (systemic or auto-immune). Idiopathic orbital inflammation corresponds to uniquely orbital inflammation without generalized disease, and thus an unknown etiology. At the top of the differential diagnosis for specific or idiopathic orbital inflammation are malignant tumors, represented most commonly in the adult by lympho-proliferative syndromes and metastases. Treatment of specific orbital inflammation begins with treatment of the underlying disease. For idiopathic orbital inflammation, treatment (most often corticosteroids) is indicated above all in cases of visual loss due to optic neuropathy, in the presence of pain or oculomotor palsy. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Application of modern tools and techniques to maximize engineering productivity in the development of orbital operations plans for the space station progrm

Science.gov (United States)

Manford, J. S.; Bennett, G. R.

1985-01-01

The Space Station Program will incorporate analysis of operations constraints and considerations in the early design phases to avoid the need for later modifications to the Space Station for operations. The application of modern tools and administrative techniques to minimize the cost of performing effective orbital operations planning and design analysis in the preliminary design phase of the Space Station Program is discussed. Tools and techniques discussed include: approach for rigorous analysis of operations functions, use of the resources of a large computer network, and providing for efficient research and access to information.

Orbit Display's Use of the Physics Application Framework

Energy Technology Data Exchange (ETDEWEB)

Zelazny, Michael; Chevtsov, Sergei; Chu, Chungming Paul; Fairley, Diane; Krejcik, Patrick; Natampalli, Partha; Rogind, Deborah; White, Greg; /SLAC

2009-12-09

At the SLAC National Accelerator Laboratory (SLAC) the Controls Department (CD) is developing a physics application framework based on the Java(tm) programming language developed by Sun Microsystems. This paper will discuss the first application developed using this approach: a new Orbit Display. The software is being developed by several individuals in reusable Java packages. It relies on the Experimental Physics and Industrial Control System (EPICS) toolkit for data collection and XAL - A Java based Hierarchy for Application Programming for model parameters. The Orbit Display tracks and displays electron paths through the Linac Coherent Light Source (LCLS) in both a graphical, beam line plot, and tabular format. It contains many features that may be unique to SLAC and is meant to be used both in the control room and by individuals in their offices or at home. Unique features include BSA Beam Synchronous Acquisition (BSA), Orbit Fitting, and Buffered Acquisition.

Topology and slowing down of high energy ion orbits

Energy Technology Data Exchange (ETDEWEB)

Eriksson, L G [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Porcelli, F [Politecnico di Torino, Turin (Italy); Berk, H L [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies

1994-07-01

An analysis of nonstandard guiding centre orbits is presented, which is relevant to MeV ions in a Tokamak. The orbit equation has been simplified from the start, allowing to present an analytic classification of the possible orbits. The topological transitions of the orbits during collisional slowing down are described. In particular, the characteristic equations reveal the existence of a single fixed point in the relevant phase plane, and the presence of a bifurcation curve corresponding to the locus of the pinch orbits. A significant particle inward pinch has been discovered. (authors). 7 figs.

Orbit Propagation and Determination of Low Earth Orbit Satellites

Directory of Open Access Journals (Sweden)

Ho-Nien Shou

2014-01-01

Full Text Available This paper represents orbit propagation and determination of low Earth orbit (LEO satellites. Satellite global positioning system (GPS configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP. The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan to use a nonlinear filtering method for immediate orbit tasks requires more precise satellite orbit state parameters in a short time. Although the traditional extended Kalman filter (EKF method is widely used, its linear approximation of the drawbacks in dealing with nonlinear problems was especially evident, without compromising Kalman filter (unscented Kalman Filter, UKF. As a new nonlinear estimation method, it is measured at the estimated measurements on more and more applications. This paper will be the first study on UKF microsatellites in LEO orbit in real time, trying to explore the real-time precision orbit determination techniques. Through the preliminary simulation results, they show that, based on orbit mission requirements and conditions using UKF, they can satisfy the positioning accuracy and compute two indicators.

Rehabilitation of orbital cavity after orbital exenteration using polymethyl methacrylate orbital prosthesis

Directory of Open Access Journals (Sweden)

Sumeet Jain

2016-01-01

Full Text Available Squamous cell carcinoma of the eyelid is the second most common malignant neoplasm of the eye with the incidence of 0.09 and 2.42 cases/100 000 people. Orbital invasion is a rare complication but, if recognized early, can be treated effectively with exenteration. Although with advancements in technology such as computer-aided design and computer-aided manufacturing, material science, and retentive methods like implants, orbital prosthesis with stock ocular prosthesis made of methyl methacrylate retained by anatomic undercuts is quiet effective and should not be overlooked and forgotten. This clinical report describes prosthetic rehabilitation of two male patients with polymethyl methacrylate resin orbital prosthesis after orbital exenteration, for squamous cell carcinoma of the upper eyelid. The orbital prosthesis was sufficiently retained by hard and soft tissue undercuts without any complications. The patients using the prosthesis are quite satisfied with the cosmetic results and felt comfortable attending the social events.

Orbital Disturbance Analysis due to the Lunar Gravitational Potential and Deviation Minimization through the Trajectory Control in Closed Loop

International Nuclear Information System (INIS)

Gonçalves, L D; Rocco, E M; De Moraes, R V

2013-01-01

A study evaluating the influence due to the lunar gravitational potential, modeled by spherical harmonics, on the gravity acceleration is accomplished according to the model presented in Konopliv (2001). This model provides the components x, y and z for the gravity acceleration at each moment of time along the artificial satellite orbit and it enables to consider the spherical harmonic degree and order up to100. Through a comparison between the gravity acceleration from a central field and the gravity acceleration provided by Konopliv's model, it is obtained the disturbing velocity increment applied to the vehicle. Then, through the inverse problem, the Keplerian elements of perturbed orbit of the satellite are calculated allowing the orbital motion analysis. Transfer maneuvers and orbital correction of lunar satellites are simulated considering the disturbance due to non-uniform gravitational potential of the Moon, utilizing continuous thrust and trajectory control in closed loop. The simulations are performed using the Spacecraft Trajectory Simulator-STRS, Rocco (2008), which evaluate the behavior of the orbital elements, fuel consumption and thrust applied to the satellite over the time

ORBITAL INJURIES

Directory of Open Access Journals (Sweden)

Andrej Kansky

2002-12-01

Full Text Available Background. Orbit is involved in 40% of all facial fractures. There is considerable variety in severity, ranging from simple nondisplaced to complex comminuted fractures. Complex comminuted fractures (up to 20% are responsible for the majority of complications and unfavorable results. Orbital fractures are classified as internal orbital fractures, zygomatico-orbital fractures, naso-orbito-ethmoidal fractures and combined fractures. The ophtalmic sequelae of midfacial fractures are usually edema and ecchymosis of the soft tissues, subconjuctival hemorrhage, diplopia, iritis, retinal edema, ptosis, enophthalmos, ocular muscle paresis, mechanical restriction of ocular movement and nasolacrimal disturbances. More severe injuries such as optic nerve trauma and retinal detachments have also been reported. Within the wide range of orbital fractures small group of complex fractures causes most of the sequelae. Therefore identification of severe injuries and adequate treatment is of major importance. The introduction of craniofacial techniques made possible a wide exposure even of large orbital wall defects and their reconstruction by bone grafts. In spite of significant progress, repair of complex orbital wall defects remains a problem even for the experienced surgeons.Results. In 1999 121 facial injuries were treated at our department (Clinical Centre Ljubljana Dept. Of Maxillofacial and Oral Surgery. Orbit was involved in 65% of cases. Isolated inner orbital fractures presented 4% of all fractures. 17 (14% complex cases were treated, 5 of them being NOE, 5 orbital (frame and inner walls, 3 zygomatico-orbital, 2 FNO and 2 maxillo-orbital fractures.Conclusions. Final result of the surgical treatment depends on severity of maxillofacial trauma. Complex comminuted fractures are responsable for most of the unfavorable results and ocular function is often permanently damaged (up to 75% in these fractures.

Orbital

OpenAIRE

Yourshaw, Matthew Stephen

2017-01-01

Orbital is a virtual reality gaming experience designed to explore the use of traditional narrative structure to enhance immersion in virtual reality. The story structure of Orbital was developed based on the developmental steps of 'The Hero's Journey,' a narrative pattern identified by Joseph Campbell. Using this standard narrative pattern, Orbital is capable of immersing the player quickly and completely for the entirety of play time. MFA

Radiation Analysis Program

Science.gov (United States)

2018-02-28

distribution is unlimited.  The second project advanced within this grant is related to beam and total dose testing of modern microcontrollers and... PROJECT NUMBER 2181 Craig Kief 5e. TASK NUMBER PPM00019523 5f. WORK UNIT NUMBER EF122950 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8...associated with on orbit assets. Research resulted in an on orbit test platform that provides the ability to observe single event upset information on the

Solar Radiation Pressure Binning for the Geosynchronous Orbit

Science.gov (United States)

Hejduk, M. D.; Ghrist, R. W.

2011-01-01

Orbital maintenance parameters for individual satellites or groups of satellites have traditionally been set by examining orbital parameters alone, such as through apogee and perigee height binning; this approach ignored the other factors that governed an individual satellite's susceptibility to non-conservative forces. In the atmospheric drag regime, this problem has been addressed by the introduction of the "energy dissipation rate," a quantity that represents the amount of energy being removed from the orbit; such an approach is able to consider both atmospheric density and satellite frontal area characteristics and thus serve as a mechanism for binning satellites of similar behavior. The geo-synchronous orbit (of broader definition than the geostationary orbit -- here taken to be from 1300 to 1800 minutes in orbital period) is not affected by drag; rather, its principal non-conservative force is that of solar radiation pressure -- the momentum imparted to the satellite by solar radiometric energy. While this perturbation is solved for as part of the orbit determination update, no binning or division scheme, analogous to the drag regime, has been developed for the geo-synchronous orbit. The present analysis has begun such an effort by examining the behavior of geosynchronous rocket bodies and non-stabilized payloads as a function of solar radiation pressure susceptibility. A preliminary examination of binning techniques used in the drag regime gives initial guidance regarding the criteria for useful bin divisions. Applying these criteria to the object type, solar radiation pressure, and resultant state vector accuracy for the analyzed dataset, a single division of "large" satellites into two bins for the purposes of setting related sensor tasking and orbit determination (OD) controls is suggested. When an accompanying analysis of high area-to-mass objects is complete, a full set of binning recommendations for the geosynchronous orbit will be available.

Orbit Functions

Directory of Open Access Journals (Sweden)

Anatoliy Klimyk

2006-01-01

Full Text Available In the paper, properties of orbit functions are reviewed and further developed. Orbit functions on the Euclidean space E_n are symmetrized exponential functions. The symmetrization is fulfilled by a Weyl group corresponding to a Coxeter-Dynkin diagram. Properties of such functions will be described. An orbit function is the contribution to an irreducible character of a compact semisimple Lie group G of rank n from one of its Weyl group orbits. It is shown that values of orbit functions are repeated on copies of the fundamental domain F of the affine Weyl group (determined by the initial Weyl group in the entire Euclidean space E_n. Orbit functions are solutions of the corresponding Laplace equation in E_n, satisfying the Neumann condition on the boundary of F. Orbit functions determine a symmetrized Fourier transform and a transform on a finite set of points.

Single-stage-to-orbit — Meeting the challenge

Science.gov (United States)

Freeman, Delma C.; Talay, Theodore A.; Austin, Robert Eugene

1996-02-01

There has been and continues to be significant discussion about the viability of fully reusable, single-stage-to-orbit (SSTO) concepts for delivery of payloads to orbit. Often, these discussions have focused in detail on performance and technology requirements relating to the technical feasibility of the concept, with only broad generalizations on how the SSTO will achieve its economic goals of greatly reduced vehicle ground and flight operations costs. With the current industry and NASA Reusable Launch Vehicle Technology Program efforts underway to mature and demonstrate technologies leading to a viable commercial launch system that also satisfies national needs, achieving acceptable recurring costs becomes a significant challenge. This paper reviews the current status of the Reusable Launch Vehicle Technology Program including the DC-XA, X-33, X-34 flight systems and associated technology programs. The paper also examines lessons learned from the recently completed DC-X reusable rocket demonstrator program. It examines how these technologies and flight systems address the technical and operability challenges of SSTO whose solutions are necessary to reduce costs. The paper also discusses the management and operational approaches that address the challenge of a new cost-effective, reusable launch vehicle system.

Autonomous orbit determination and its error analysis for deep space using X-ray pulsar

International Nuclear Information System (INIS)

Feng, Dongzhu; Yuan, Xiaoguang; Guo, Hehe; Wang, Xin

2014-01-01

Autonomous orbit determination (OD) is a complex process using filtering method to integrate observation and orbit dynamic model effectively and estimate the position and velocity of a spacecraft. As a novel technology for autonomous interplanetary OD, X-ray pulsar holds great promise for deep space exploration. The position and velocity of spacecraft should be estimated accurately during the OD process. However, under the same condition, the accuracy of OD can be greatly reduced by the error of the initial orbit value and the orbit mutation. To resolve this problem, we propose a novel OD method, which is based on the X-ray pulsar measurement and Adaptive Unscented Kalman Filter (AUKF). The accuracy of OD can be improved obviously because the AUKF estimates the orbit of spacecraft using measurement residual. During the simulation, the orbit of Phoenix Mars Lander, Deep Impact Probe, and Voyager 1 are selected. Compared with Unscented Kalman Filter (UKF) and Extended Kalman Filter (EKF), the simulation results demonstrate that the proposed OD method based on AUKF can accurately determinate the velocity and position and effectively decrease the orbit estimated errors which is caused by the orbit mutation and orbit initial errors. (authors)

CryoSat/SIRAL Cal1 Calibration Orbits

Science.gov (United States)

Scagliola, Michele; Fornari, Marco; Bouffard, Jerome; Parrinello, Tommaso

2017-04-01

The main payload of CryoSat is a Ku band pulsewidth limited radar altimeter, called SIRAL (Synthetic interferometric radar altimeter), that transmits pulses at a high pulse repetition frequency thus making the received echoes phase coherent and suitable for SAR processing. This allows to reach an along track resolution that is significantly improved with respect to traditional pulse-width limited altimeters. Due to the fact that SIRAL is a phase coherent pulse-width limited radar altimeter, a proper calibration approach has been developed. In fact, not only corrections for transfer function, gain and instrument path delay have to be computed (as in previous altimeters), but also corrections for phase (SAR/SARIn) and phase difference between the two receiving chains (SARIN only). Recalling that the CryoSat's orbit has a high inclination of 92° and it is non-sun-synchronous, the temperature of the SIRAL changes continuously along the orbit with a period of about 480 days and it is also function of the ascending/descending passes. By analysis of the CAL1 calibration corrections, it has been verified that the internal path delay and the instrument gain variation measured on the SIRAL are affected by the thermal status of the instrument and as a consequence they are expected to vary along the orbit. In order to gain knowledge on the calibration corrections (i.e. the instrument behavior) as function of latitude and temperature, it has been planned to command a few number of orbits where only CAL1 calibration acquisitions are continuously performed. The analysis of the CAL1 calibration corrections produced along the Calibration orbits can be also useful to verify whether the current calibration plan is able to provide sufficiently accurate corrections for the instrument acquisitions at any latitude. In 2016, the CryoSat/SIRAL Cal1 Calibration Orbits have been commanded two times, a first time the 20th of July 2016 and a second time the 24th of November 2016, and they

Primary Orbital Chondromyxoid Fibroma: A Rare Case.

Science.gov (United States)

Mullen, Martin G; Somogyi, Marie; Maxwell, Sean P; Prabhu, Vikram; Yoo, David K

A 56-year-old male with history of chronic sinusitis was found to have a 3 cm left orbital lesion on CT. Subsequent MRI demonstrated a multilobulated enhancing soft tissue lesion at the superotemporal region of the left orbit. Initial biopsy was reported as a low-grade sarcoma. On further evaluation, a consensus was made that the lesion was likely a benign mixed mesenchymal type tumor but should nonetheless be surgically removed. Left lateral orbitotomy was performed which revealed a tumor originating in the lateral orbital bone with segments eroding through the wall of the orbit. Intraoperative frozen sections revealed myoepitheliod tissue with locally aggressive features and the tumor was completely removed. The final histopathologic analysis of the tissue was consistent with a chondromyxoid fibroma. Chondomyxoid fibroma is a rare entity in the orbital bones and is more commonly seen in long bones.

Global communication using a constellation of low earth meridian orbits

Science.gov (United States)

Oli, P. V. S.; Nagarajan, N.; Rayan, H. R.

1993-07-01

The concept of 'meridian orbits' is briefly reviewed. It is shown that, if a satellite in the meridian orbit makes an odd number of revolutions per day, then the satellite passes over the same set of meridians twice a day. Satellites in such orbits pass over the same portion of the sky twice a day and every day. This enables a user to adopt a programmed mode of tracking, thereby avoiding a computational facility for orbit prediction, look angle generation, and auto tracking. A constellation of 38 or more satellites placed in a 1200 km altitude circular orbit is favorable for global communications due to various factors. It is shown that appropriate phasing in right ascension of the ascending node and mean anomaly results in a constellation, wherein each satellite appears over the user's horizon one satellite after another. Visibility and coverage plots are provided to verify the continuous coverage.

Dynamics of Orbits near 3:1 Resonance in the Earth-Moon System

Science.gov (United States)

Dichmann, Donald J.; Lebois, Ryan; Carrico, John P., Jr.

2013-01-01

The Interstellar Boundary Explorer (IBEX) spacecraft is currently in a highly elliptical orbit around Earth with a period near 3:1 resonance with the Moon. Its orbit is oriented so that apogee does not approach the Moon. Simulations show this orbit to be remarkably stable over the next twenty years. This article examines the dynamics of such orbits in the Circular Restricted 3-Body Problem (CR3BP). We look at three types of periodic orbits, each exhibiting a type of symmetry of the CR3BP. For each of the orbit types, we assess the local stability using Floquet analysis. Although not all of the periodic solutions are stable in the mathematical sense, any divergence is so slow as to produce practical stability over several decades. We use Poincare maps with twenty-year propagations to assess the nonlinear stability of the orbits, where the perturbation magnitudes are related to the orbit uncertainty for the IBEX mission. Finally we show that these orbits belong to a family of orbits connected in a bifurcation diagram that exhibits exchange of stability. The analysis of these families of period orbits provides a valuable starting point for a mission orbit trade study.

Orbit monitoring in the SLC

International Nuclear Information System (INIS)

Sanchez-Chopitea, L.; Emma, P.; Van Olst, D.

1991-05-01

Beam orbits in the SLC are monitored in real time and the data is stored for future trend and correlation analysis. A background process acquires Beam Position Monitor (BPM) and Toroid data on a periodic basis and saves the general quantities such as orbit RMS and beam intensity in addition to the individual readings. Some of this data is archived by the SLC History Buffer facility and the rest is saved in files for later analysis. This has permitted the tracing of interaction point instabilities to specific devices as far away as the damping rings. In addition, the data is displayed for the operators both in summary and in full form. The different displays can be configured from the control consoles. 2 refs., 5 figs

Hypersonic Navier Stokes Comparisons to Orbiter Flight Data

Science.gov (United States)

Campbell, Charles H.; Nompelis, Ioannis; Candler, Graham; Barnhart, Michael; Yoon, Seokkwan

2009-01-01

Hypersonic chemical nonequilibrium simulations of low earth orbit entry flow fields are becoming increasingly commonplace as software and computational capabilities become more capable. However, development of robust and accurate software to model these environments will always encounter a significant barrier in developing a suite of high quality calibration cases. The US3D hypersonic nonequilibrium Navier Stokes analysis capability has been favorably compared to a number of wind tunnel test cases. Extension of the calibration basis for this software to Orbiter flight conditions will provide an incremental increase in confidence. As part of the Orbiter Boundary Layer Transition Flight Experiment and the Hypersonic Thermodynamic Infrared Measurements project, NASA is performing entry flight testing on the Orbiter to provide valuable aerothermodynamic heating data. An increase in interest related to orbiter entry environments is resulting from this activity. With the advent of this new data, comparisons of the US3D software to the new flight testing data is warranted. This paper will provide information regarding the framework of analyses that will be applied with the US3D analysis tool. In addition, comparisons will be made to entry flight testing data provided by the Orbiter BLT Flight Experiment and HYTHIRM projects. If data from digital scans of the Orbiter windward surface become available, simulations will also be performed to characterize the difference in surface heating between the CAD reference OML and the digitized surface provided by the surface scans.

Investigation of electrodynamic stabilization and control of long orbiting tethers

Science.gov (United States)

Colombo, G.; Arnold, D.

1984-01-01

The state-of-the-art in tether modelling among participants in the Tethered Satellite System (TSS) Program, the slack tether and its behavior, and certain advanced applications of the tether to problems in orbital mechanics are identified. The features and applications of the TSS software set are reviewed. Modelling the slack tether analytically with as many as 50 mass points and the application of this new model to a study of the behavior of a broken tether near the Shuttle are described. A reel control algorithm developed by SAO and examples of its use are described, including an example which also demonstrates the use of the tether in transferring a heavy payload from a low-orbiting Shuttle to a high circular orbit. Capture of a low-orbiting payload by a Space Station in high circular orbit is described. Energy transfer within a dumbbell-type spacecraft by cyclical reeling operations or gravitational effects on the natural elasticity of the connecting tether, it is shown, can circularize the orbit of the spacecraft.

Orbital motion in strongly perturbed environments applications to asteroid, comet and planetary satellite orbiters

CERN Document Server

Scheeres, Daniel J

2012-01-01

The proposed book will provide a detailed, technical introduction to the analysis of orbital motion in strongly perturbed environments, focusing on motion about small Solar System bodies, such as comets and asteroids. The author shows why such small bodies are of interest and why they can be used as a motivation for the general analysis of orbital mechanics. He shows how it is possible to model the small body environment, including specialised cases such as those of binary asteroids, comets and ‘rubble piles’, and how the fundamental equations of motion are derived. The properties of the various solutions to the equations of motion are described and the methods of analysis and their application are discussed. Both ballistic motion and powered motion on and about small bodies are considered and case studies for different small body missions are presented. The author concludes his comprehensive treatment with a discussion of the mechanics of multi-body small body systems and a review of advanced topics and ...

Analysis of the Effect of UTI-UTC to High Precision Orbit

Science.gov (United States)

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.

Orbital Express Mission Operations Planning and Resource Management using ASPEN

Science.gov (United States)

Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Danny

2008-01-01

The Orbital Express satellite servicing demonstrator program is a DARPA program aimed at developing "a safe and cost-effective approach to autonomously service satellites in orbit". The system consists of: a) the Autonomous Space Transport Robotic Operations (ASTRO) vehicle, under development by Boeing Integrated Defense Systems, and b) a prototype modular next-generation serviceable satellite, NEXTSat, being developed by Ball Aerospace. Flexibility of ASPEN: a) Accommodate changes to procedures; b) Accommodate changes to daily losses and gains; c) Responsive re-planning; and d) Critical to success of mission planning Auto-Generation of activity models: a) Created plans quickly; b) Repetition/Re-use of models each day; and c) Guarantees the AML syntax. One SRP per day vs. Tactical team

Formation flying for electric sails in displaced orbits. Part I: Geometrical analysis

Science.gov (United States)

Wang, Wei; Mengali, Giovanni; Quarta, Alessandro A.; Yuan, Jianping

2017-09-01

We present a geometrical methodology for analyzing the formation flying of electric solar wind sail based spacecraft that operate in heliocentric, elliptic, displaced orbits. The spacecraft orbit is maintained by adjusting its propulsive acceleration modulus, whose value is estimated using a thrust model that takes into account a variation of the propulsive performance with the sail attitude. The properties of the relative motion of the spacecraft are studied in detail and a geometrical solution is obtained in terms of relative displaced orbital elements, assumed to be small quantities. In particular, for the small eccentricity case (i.e. for a near-circular displaced orbit), the bounds characterized by the extreme values of relative distances are analytically calculated, thus providing an useful mathematical tool for preliminary design of the spacecraft formation structure.

Correction of the equilibrium orbit at the Bonn 3.5 GeV electron stretcher facility ELSA

International Nuclear Information System (INIS)

Wenzel, J.

1990-09-01

A beam position monitor system is being built for the Bonn electron stretcher facility ELSA. Based on the ELSA monitor system the Closed Orbit Correction Program for Interactive Tasks COCPIT has been developed. It enables an online correction of the closed orbit and is fully integrated into the ELSA operating system which allows control of all steering and diagnostic facilities of ELSA. COCPIT implements least square and harmonic correction methods with choosable harmonic components. A statistical analysis shows which correction method is best under given circumstances. Furthermore data about the current status of the monitor system as well as the corrector system enter the correction. Monitor offsets are added to the position measurements and the corrector-dipoles maximum currents are accounted for as constraints. Computer simulations prove the proper work of COCPIT and the validity of the statistical analysis. Possibilities of a future development of COCPIT are shown. (orig.) [de

ERS orbit control

Science.gov (United States)

Rosengren, Mats

1991-12-01

The European remote sensing mission orbit control is addressed. For the commissioning phase, the orbit is defined by the following requirements: Sun synchronous, local time of descending node 10:30; three days repeat cycle with 43 orbital revolutions; overhead Venice tower (12.508206 deg east, 45.314222 deg north). The launch, maneuvers for the initial acquisition of the operational orbit, orbit maintenance maneuvers, evaluation of the orbit control, and the drift of the inclination are summarized.

The Results of Complex Research of GSS "SBIRS-Geo 2" Behavior in the Orbit

Science.gov (United States)

Sukhov, P. P.; Epishev, V. P.; Sukhov, K. P.; Karpenko, G. F.; Motrunich, I. I.

2017-04-01

The new generation of geosynchronous satellites SBIRS of US Air Force early warning system series (Satellite Early Warning System) replaced the previous DSP-satellite series (Defense Support Program). Currently from the territory of Ukraine, several GSS of DSP series and one "SBIRS-Geo 2" are available to observation. During two years of observations, we have received and analyzed for two satellites more than 30 light curves in B, V, R photometric system. As a result of complex research, we propose a model of "SBIRS-Geo" 2 orbital behavior compared with the same one of the DSP-satellite. To control the entire surface of the Earth with 15-16 sec interval, including the polar regions, 4 SBIRS satellites located every 90 deg. along the equator are enough in GEO orbit. Since DSP-satellites provide the coverage of the Earth's surface to 83 deg. latitudes with a period of 50 sec, DSP-satellites should be 8. All the conclusions were made based on an analysis of photometric and coordinate observations using the simulation of the dynamics of their orbital behavior.

Servicing communication satellites in geostationary orbit

Science.gov (United States)

Russell, Paul K.; Price, Kent M.

1990-01-01

The econmic benefits of a LEO space station are quantified by identifying alternative operating scenarios utilizing the space station's transportation facilities and assembly and repair facilities. Particular consideration is given to the analysis of the impact of on-orbit assembly and servicing on a typical communications satellite is analyzed. The results of this study show that on-orbit servicing can increase the internal rate of return by as much as 30 percent.

Energy and the Elliptical Orbit

Science.gov (United States)

Nettles, Bill

2009-03-01

In the January 2007 issue of The Physics Teacher, Prentis, Fulton, Hesse, and Mazzino describe a laboratory exercise in which students use a geometrical analysis inspired by Newton to show that an elliptical orbit and an inverse-square law force go hand in hand. The historical, geometrical, and teamwork aspects of the exercise are useful and important. This paper presents an exercise which uses an energy/angular momentum conservation model for elliptical orbits. This exercise can be done easily by an individual student and on regular notebook-sized paper.

A Typical Presentation of Orbital Pseudotumor Mimicking Orbital Cellulitis

Directory of Open Access Journals (Sweden)

J. Ayatollahi

2013-10-01

Full Text Available Introduction: Orbital pseudotumor, also known as idiopathic orbital inflammatory syndrome (IOIS, is a benign, non- infective inflammatory condition of the orbit without identifiable local or systemic causes. The disease may mimics a variety of pathologic conditions. We pre-sent a case of pseudotumor observed in a patient admitted under the name of orbital celluli-ties. Case Report: A 26-year-old woman reffered to our hospital with the history of left ocular pain and headache 2 days before her visit.. Ophthalmological examination of the patient was normal except for the redness and lid edema, mild chemosis and conjunctival injection. Gen-eral assessment was normal but a low grade fever was observed. She was hospitalized as an orbital cellulitis patient. She was treated with intravenous antibiotics. On the third day , sud-denly diplopia, proptosis in her left eye and ocular pain in her right side appeared. MRI re-vealed bilateral enlargement of extraocular muscles. Diagnosis of orbital pseudotumor was made and the patient was treated with oral steroid.She responded promptly to the treatment. Antibiotics were discontinued and steroid was tapered in one month period under close fol-low up. Conclusion: The clinical features of orbital pseudotumor vary widely . Orbital pseudotumor and orbital cellulitis can occasionally demonstrate overlapping features.. Despite complete physical examination and appropriate imaging, sometimes correct diagnosis of the disease would be difficult (Sci J Hamadan Univ Med Sci 2013; 20 (3:256-259

Orbital stability analysis in biomechanics: a systematic review of a nonlinear technique to detect instability of motor tasks.

Science.gov (United States)

Riva, F; Bisi, M C; Stagni, R

2013-01-01

Falls represent a heavy economic and clinical burden on society. The identification of individual chronic characteristics associated with falling is of fundamental importance for the clinicians; in particular, the stability of daily motor tasks is one of the main factors that the clinicians look for during assessment procedures. Various methods for the assessment of stability in human movement are present in literature, and methods coming from stability analysis of nonlinear dynamic systems applied to biomechanics recently showed promise. One of these techniques is orbital stability analysis via Floquet multipliers. This method allows to measure orbital stability of periodic nonlinear dynamic systems and it seems a promising approach for the definition of a reliable motor stability index, taking into account for the whole task cycle dynamics. Despite the premises, its use in the assessment of fall risk has been deemed controversial. The aim of this systematic review was therefore to provide a critical evaluation of the literature on the topic of applications of orbital stability analysis in biomechanics, with particular focus to methodologic aspects. Four electronic databases have been searched for articles relative to the topic; 23 articles were selected for review. Quality of the studies present in literature has been assessed with a customised quality assessment tool. Overall quality of the literature in the field was found to be high. The most critical aspect was found to be the lack of uniformity in the implementation of the analysis to biomechanical time series, particularly in the choice of state space and number of cycles to include in the analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

GOC: General Orbit Code. [In FORTRAN for IBM 360

Energy Technology Data Exchange (ETDEWEB)

Maddox, L.B.; McNeilly, G.S.

1979-08-01

GOC (General Orbit Code) is a versatile program which will perform a variety of calculations relevant to isochronous cyclotron design studies. In addition to the usual calculations of interest (e.g., equilibrium and accelerated orbits, focusing frequencies, field isochronization, etc.), GOC has a number of options to calculate injections with a charge change. GOC provides both printed and plotted output, and will follow groups of particles to allow determination of finite-beam properties. An interactive PDP-10 program called GIP, which prepares input data for GOC, is available. GIP is a very easy and convenient way to prepare complicated input data for GOC. Enclosed with this report are several microfiche containing source listings of GOC and other related routines and the printed output from a multiple-option GOC run.

Deadly Sunflower Orbits

Science.gov (United States)

Hamilton, Douglas P.

2018-04-01

Solar radiation pressure is usually very effective at removing hazardous millimeter-sized debris from distant orbits around asteroidsand other small solar system bodies (Hamilton and Burns 1992). Theprimary loss mechanism, driven by the azimuthal component of radiationpressure, is eccentricity growth followed by a forced collision withthe central body. One large class of orbits, however, neatly sidestepsthis fate. Orbits oriented nearly perpendicular to the solar directioncan maintain their face-on geometry, oscillating slowly around a stableequilibrium orbit. These orbits, designated sunflower orbits, arerelated to terminator orbits studied by spacecraft mission designers(Broschart etal. 2014).Destabilization of sunflower orbits occurs only for particles smallenough that radiation pressure is some tens of percent the strength ofthe central body's direct gravity. This greatly enhanced stability,which follows from the inability of radiation incident normal to theorbit to efficiently drive eccentricities, presents a threat tospacecraft missions, as numerous dangerous projectiles are potentiallyretained in orbit. We have investigated sunflower orbits insupport of the New Horizons, Aida, and Lucy missions and find thatthese orbits are stable for hazardous particle sizes at asteroids,comets, and Kuiper belt objects of differing dimensions. Weinvestigate the sources and sinks for debris that might populate suchorbits, estimate timescales and equilibrium populations, and willreport on our findings.

A probabilistic analysis of the implications of instrument failures on ESA's Swarm mission for its individual satellite orbit deployments

Science.gov (United States)

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.

Spacetime and orbits of bumpy black holes

International Nuclear Information System (INIS)

Vigeland, Sarah J.; Hughes, Scott A.

2010-01-01

Our Universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine if they have the spacetime structure that general relativity demands. As a means of formulating measurements to test the black hole nature of these objects, Collins and Hughes introduced ''bumpy black holes'': objects that are almost, but not quite, general relativity's black holes. The spacetimes of these objects have multipoles that deviate slightly from the black hole solution, reducing to black holes when the deviation is zero. In this paper, we extend this work in two ways. First, we show how to introduce bumps which are smoother and lead to better behaved orbits than those in the original presentation. Second, we show how to make bumpy Kerr black holes--objects which reduce to the Kerr solution when the deviation goes to zero. This greatly extends the astrophysical applicability of bumpy black holes. Using Hamilton-Jacobi techniques, we show how a spacetime's bumps are imprinted on orbital frequencies, and thus can be determined by measurements which coherently track the orbital phase of a small orbiting body. We find that in the weak field, orbits of bumpy black holes are modified exactly as expected from a Newtonian analysis of a body with a prescribed multipolar structure, reproducing well-known results from the celestial mechanics literature. The impact of bumps on strong-field orbits is many times greater than would be predicted from a Newtonian analysis, suggesting that this framework will allow observations to set robust limits on the extent to which a spacetime's multipoles deviate from the black hole expectation.

A method for volume determination of the orbit and its contents by high resolution axial tomography and quantitative digital image analysis.

Science.gov (United States)

Cooper, W C

1985-01-01

The various congenital and acquired conditions which alter orbital volume are reviewed. Previous investigative work to determine orbital capacity is summarized. Since these studies were confined to postmortem evaluations, the need for a technique to measure orbital volume in the living state is presented. A method for volume determination of the orbit and its contents by high-resolution axial tomography and quantitative digital image analysis is reported. This procedure has proven to be accurate (the discrepancy between direct and computed measurements ranged from 0.2% to 4%) and reproducible (greater than 98%). The application of this method to representative clinical problems is presented and discussed. The establishment of a diagnostic system versatile enough to expand the usefulness of computerized axial tomography and polytomography should add a new dimension to ophthalmic investigation and treatment.

Numerical analysis of orbital transfers to Mars using solar sails and attitude control

Science.gov (United States)

Pereira, M. C.; de Melo, C. F.; Meireles, L. G.

2017-10-01

Solar sails present a promising alternative method of propulsion for the coming phases of the space exploration. With the recent advances in materials engineering, the construction of lighter and more resistant materials capable of impelling spaceships with the use of solar radiation pressure has become increasingly viable technologically and economically. The studies, simulations and analysis of orbital transfers from Earth to Mars proposed in this work were implemented considering the use of a flat solar sail. Maneuvers considering the delivery of a sailcraft from a Low Earth Orbit to the border of the Earth’s sphere of influence and interplanetary trajectories to Mars were investigated. A set of simulations were implemented varying the attitude of the sail relative to the Sun. Results show that a sailcraft can carry out transfers with final velocity with respect to Mars smaller than the interplanetary Patched-conic approximation, although this requires a longer time of transfers, provided the attitude of the sailcraft relative to the Sun can be controlled in some points of the trajectories.

Calibration of the x-ray ring quadrupoles, BPMs, and orbit correctors using the measured orbit response matrix

International Nuclear Information System (INIS)

Safranek, J.; Lee, M.

1994-02-01

The quadrupole strengths, beam position monitor (BPM) gains, and orbit correction magnet strengths were adjusted in a computer model of the NSLS X-Ray ring in order to best fit the model orbit response matrix to the measured matrix. The model matrix was fit tot the 4320 data points in the measured matrix with an rms difference of only 2 to 3 microns, which is due primarily to noise in the BPM measurements. The strengths of the 56 individual quadrupoles in the X-Ray ring were determined to an accuracy of about 0.2%. The BPM and orbit corrector calibrations were also accurately determined. A through analysis of both random and systematic errors is included

A retrograde co-orbital asteroid of Jupiter.

Science.gov (United States)

Wiegert, Paul; Connors, Martin; Veillet, Christian

2017-03-29

Recent theoretical work in celestial mechanics has revealed that an asteroid may orbit stably in the same region as a planet, despite revolving around the Sun in the sense opposite to that of the planet itself. Asteroid 2015 BZ 509 was discovered in 2015, but with too much uncertainty in its measured orbit to establish whether it was such a retrograde co-orbital body. Here we report observations and analysis that demonstrates that asteroid 2015 BZ 509 is indeed a retrograde co-orbital asteroid of the planet Jupiter. We find that 2015 BZ 509 has long-term stability, having been in its current, resonant state for around a million years. This is long enough to preclude precise calculation of the time or mechanism of its injection to its present state, but it may be a Halley-family comet that entered the resonance through an interaction with Saturn. Retrograde co-orbital asteroids of Jupiter and other planets may be more common than previously expected.

Orbits

CERN Document Server

Xu, Guochang

2008-01-01

This is the first book of the satellite era which describes orbit theory with analytical solutions of the second order with respect to all possible disturbances. Based on such theory, the algorithms of orbits determination are completely revolutionized.

Four Years on Orbit at the Moon with LOLA

Science.gov (United States)

Smith, D. E.; Zuber, M. T.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; Lemoine, F. G.

2013-12-01

After four years of near-continuous operation at the Moon, the Lunar Orbiter Laser Altimeter (LOLA) continues to collect altimetry, surface roughness, slope and normal reflectance data. Although the instrument is beginning to show the effects of tens of thousands of thermal cycles and the natural process of the aging of the laser transmitters, LOLA continues to acquire data on the sunlit portion of every orbit on all 5 laser beams when below 100-km altitude. LOLA has acquired over 6x10^9 altimeter measurements, all geodetically controlled to the center-of-mass of the Moon with a radial precision of around 10 cm and an accuracy of about 1 meter. The position of the measurements on the lunar surface is primarily limited by the knowledge of the position of the spacecraft in orbit; in the last year the LRO orbit accuracy has improved significantly as a result of the availability of an accurate gravity model of the Moon from the GRAIL Discovery mission. Our present estimate of positional accuracy is less than 10 m rms but is only achievable with a GRAIL gravity model to at least degree and order 600 because of the perturbing gravitational effect of the Moon's surface features. Significant improvements in the global shape and topography have assisted the Lunar Reconnaissance Orbiter Camera (LROC) stereo mapping program, and the identification of potential lunar landing sites for ESA and Russia, particularly in the high-latitude polar regions where 5- and 10-meter average horizontal resolution has been obtained. LOLA's detailed mapping of the polar regions has improved the delineation of permanently-shadowed areas and assisted in the understanding of the LEND neutron data and its relationship to surface slopes. Recently, a global, calibrated LOLA normal albedo dataset at 1064 nm has been developed and is being combined with analysis and modeling by the Diviner team for the identification of the coldest locations in the polar regions.

Multi-layered foil capture of micrometeoroids and orbital debris in low Earth orbit

Science.gov (United States)

Kearsley, A.; Graham, G.

Much of our knowledge concerning the sub-millimetre orbital debris population that poses a threat to orbiting satellites has been gleaned from examination of surfaces retrieved and subsequently analysed as part of post-flight investigations. The preservation of the hypervelocity impact-derived remnants located on these surfaces is very variable, whether of space debris or micrometeoroid origin. Whilst glass and metallic materials show highly visible impact craters when examined using optical and electron microscopes, complex mixing between the target material and the impacting particle may make unambiguous interpretation of the impactor origin difficult or impossible. Our recent detailed examination of selected multi-layered insulation (MLI) foils from the ISAS Space Flyer Unit (SFU), and our preliminary study of NASA's Trek blanket, exposed on the Mir station, show that these constructions have the potential to preserve abundant residue material of a quality sufficient for detailed analysis. Although there are still limitations on the recognition of certain sources of orbital debris, the foils complement the metal and glass substrates. We suggest that a purpose-built multi-layered foil structure may prove to be extremely effective for rapid collection and unambiguous analysis of impact- derived residues. Such a collector could be used an environmental monitor for ISS, as it would have low mass, high durability, easy deployment, recovery and storage, making it an economically viable and attractive option.

On the formation of an instantaneous orbit in a synchrotron

International Nuclear Information System (INIS)

Bashmakov, Yu.A.; Karpov, V.A.

1985-01-01

In the process of injection into a synchrotron amplitudes of particle betatron oscillations can be comparable with the dimensions of the synchrotron working region, which means that special attention should be paid to the formation of the optimum instantaneous orbit. Basides, a necessity to calculate the orbit frequently arises at the end of the acceleration cycle, when particle dump onto internal targets or their extraction from the synchrotron take place. In the paper the method for calculation of particle trajectories in the synchrotron is described. According to the method the program of numerical calculation of both separate particle trajectories and closed instantaneous orbit was developed. The method suggested is based on the presentation of the accelerator magnetic structure as a sequential set of discrete elements. All the elements can be divided into the following main groups: free rectilinear gaps, rectilinear gaps with stray magnetic field, magnetic sectors, rectilinear gaps with accelerating electric field. The calculations made according to the method described have shown its high efficiency. The program developed is used for the simulation of the injection into the ''Pakhra'' synchrotron

Orbital Chondroma: A rare mesenchymal tumor of orbit

Directory of Open Access Journals (Sweden)

Ruchi S Kabra

2015-01-01

Full Text Available While relatively common in the skeletal system, cartilaginous tumors are rarely seen originating from the orbit. Here, we report a rare case of an orbital chondroma. A 27-year-old male patient presented with a painless hard mass in the superonasal quadrant (SNQ of left orbit since 3 months. On examination, best-corrected visual acuity of both eyes was 20/20, with normal anterior and posterior segment with full movements of eyeballs and normal intraocular pressure. Computerized tomography scan revealed well defined soft tissue density lesion in SNQ of left orbit. Patient was operated for anteromedial orbitotomy under general anesthesia. Mass was excised intact and sent for histopathological examination (HPE. HPE report showed lobular aggregates of benign cartilaginous cells with mild atypia suggesting of benign cartilaginous tumor - chondroma. Very few cases of orbital chondroma have been reported in literature so far.

Orbital period changes in RW CrA, DX Vel and V0646 Cen

Science.gov (United States)

Volkov, I. M.; Chochol, D.; Grygar, J.; Mašek, M.; Juryšek, J.

2017-06-01

We aim to determine the absolute parameters of the components of southern Algol-type binaries with deep eclipses RW CrA, DX Vel, V0646 Cen and interpret their orbital period changes. The data analysis is based on a high quality Walraven photoelectric photometry, obtained in the 1960-70s, our recent CCD photometry, ASAS (Pojmanski, 2002), and Hipparcos (Perryman et al., 1997) photometry of the objects. Their light curves were analyzed using the PHOEBE program with fixed effective temperatures of the primary components, found from disentangling the Walraven (B-U) and (V-B) colour indices. We found the absolute parameters of the components of all three objects. All reliable observed times of minimum light were used to construct and analyze the Eclipse Time Variation (ETV) diagrams. We interpreted the ETV diagrams of the detached binary RW CrA and the semi-detached binary DX Vel by a LIght-Time Effect (LITE), estimated parameters of their orbits and masses of their third bodies. We suggest a long term variation of the inclination angle of both eclipsing binaries, caused by a non-coplanar orientation of their third body orbits. We interpreted the detected orbital period increase in the semi-detached binary V0646 Cen by a mass transfer from the less to more massive component with the rate M⊙ = 6.08×10-9 M⊙/yr.

Experimental Space Shuttle Orbiter Studies to Acquire Data for Code and Flight Heating Model Validation

Science.gov (United States)

Wadhams, T. P.; Holden, M. S.; MacLean, M. G.; Campbell, Charles

2010-01-01

thin-film resolution in both the span and chord direction in the area of peak heating. Additional objectives of this first study included: obtaining natural or tripped turbulent wing leading edge heating levels, assessing the effectiveness of protuberances and cavities placed at specified locations on the orbiter over a range of Mach numbers and Reynolds numbers to evaluate and compare to existing engineering and computational tools, obtaining cavity floor heating to aid in the verification of cavity heating correlations, acquiring control surface deflection heating data on both the main body flap and elevons, and obtain high speed schlieren videos of the interaction of the orbiter nose bow shock with the wing leading edge. To support these objectives, the stainless steel 1.8% scale orbiter model in addition to the sensors on the wing leading edge was instrumented down the windward centerline, over the wing acreage on the port side, and painted with temperature sensitive paint on the starboard side wing acreage. In all, the stainless steel 1.8% scale Orbiter model was instrumented with over three-hundred highly sensitive thin-film heating sensors, two-hundred of which were located in the wing leading edge shock interaction region. Further experimental studies will also be performed following the successful acquisition of flight data during the Orbiter Entry Boundary Layer Flight Experiment and HYTHIRM on STS-119 at specific data points simulating flight conditions and geometries. Additional instrumentation and a protuberance matching the layout present during the STS-119 boundary layer transition flight experiment were added with testing performed at Mach number and Reynolds number conditions simulating conditions experienced in flight. In addition to the experimental studies, CUBRC also performed a large amount of CFD analysis to confirm and validate not only the tunnel freestream conditions, but also 3D flows over the orbiter acreage, wing leading edge, and

Static Analysis of Mobile Programs

Science.gov (United States)

2017-02-01

and not allowed, to do. The second issue was that a fully static analysis was never a realistic possibility, because Java , the programming langauge...scale to large programs it had to handle essentially all of the features of Java and could also be used as a general-purpose analysis engine. The...static analysis of imperative languages. • A framework for adding specifications about the behavior of methods, including methods that were

Orbiter CCTV video signal noise analysis

Science.gov (United States)

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.

Critical hand ischemia treatment via orbital atherectomy-A single center observational retrospective analysis.

Science.gov (United States)

Bahro, Abdul; Igyarto, Zsuzsanna; Martinsen, Brad

2017-03-01

Critical hand ischemia (CHI) can be devastating and may result in amputation. Distal vessel calcification has been shown to be a major factor in causing CHI. Atherectomy in the upper extremities is not typically considered due to the small anatomy; however, the Diamondback 360° Peripheral Orbital Atherectomy System (OAS) (Cardiovascular Systems, Inc.) can access treatment areas with a reference vessel diameter of 1.5mm. A retrospective, observational, single center (Merit Health Center, Jackson, MS) analysis of 11 CHI patients with calcific disease of the radial artery treated with orbital atherectomy (OAS) was completed. Demographics and procedural to 30-day outcomes were assessed. All patients had good blood flow to the hand after intervention and none experienced complications during or immediately post-procedure. At 30-days the freedom from revascularization and amputation was 100%, and all the wounds were healed. The following important principles were followed during the use of OAS for CHI: (1) ACT was therapeutic (~250s); (2) Gentle wire manipulation; (3) Utilization of a small OAS crown (1.25mm); (4) Aggressive vasodilator use-given through the exchange catheter; (5) Angioplasty balloon was matched to the size of the vessel and long and low pressure inflations were completed. Critical hand ischemia can be treated with endovascular techniques. Obtaining good outflow to the fingers is critical for wound healing and preventing amputation. Orbital atherectomy is a useful tool in preparing vessels for balloon angioplasty; particularly in cases where calcification is present. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

A Delphi-Based Framework for systems architecting of in-orbit exploration infrastructure for human exploration beyond Low Earth Orbit

Science.gov (United States)

Aliakbargolkar, Alessandro; Crawley, Edward F.

2014-01-01

The current debate in the U.S. Human Spaceflight Program focuses on the development of the next generation of man-rated heavy lift launch vehicles. While launch vehicle systems are of critical importance for future exploration, a comprehensive analysis of the entire exploration infrastructure is required to avoid costly pitfalls at early stages of the design process. This paper addresses this need by presenting a Delphi-Based Systems Architecting Framework for integrated architectural analysis of future in-orbit infrastructure for human space exploration beyond Low Earth Orbit. The paper is structured in two parts. The first part consists of an expert elicitation study to identify objectives for the in-space transportation infrastructure. The study was conducted between November 2011 and January 2012 with 15 senior experts involved in human spaceflight in the United States and Europe. The elicitation study included the formation of three expert panels representing exploration, science, and policy stakeholders engaged in a 3-round Delphi study. The rationale behind the Delphi approach, as imported from social science research, is discussed. Finally, a novel version of the Delphi method is presented and applied to technical decision-making and systems architecting in the context of human space exploration. The second part of the paper describes a tradespace exploration study of in-orbit infrastructure coupled with a requirements definition exercise informed by expert elicitation. The uncertainties associated with technical requirements and stakeholder goals are explicitly considered in the analysis. The outcome of the expert elicitation process portrays an integrated view of perceived stakeholder needs within the human spaceflight community. Needs are subsequently converted into requirements and coupled to the system architectures of interest to analyze the correlation between exploration, science, and policy goals. Pareto analysis is used to identify architectures

Shuttle user analysis (study 2.2): Volume 3. Business Risk And Value of Operations in space (BRAVO). Part 4: Computer programs and data look-up

Science.gov (United States)

1974-01-01

Computer program listings as well as graphical and tabulated data needed by the analyst to perform a BRAVO analysis were examined. Graphical aid which can be used to determine the earth coverage of satellites in synchronous equatorial orbits was described. A listing for satellite synthesis computer program as well as a sample printout for the DSCS-11 satellite program and a listing of the symbols used in the program were included. The APL language listing for the payload program cost estimating computer program was given. This language is compatible with many of the time sharing remote terminals computers used in the United States. Data on the intelsat communications network was studied. Costs for telecommunications systems leasing, line of sight microwave relay communications systems, submarine telephone cables, and terrestrial power generation systems were also described.

Local orbitals by minimizing powers of the orbital variance

DEFF Research Database (Denmark)

Jansik, Branislav; Høst, Stinne; Kristensen, Kasper

2011-01-01

's correlation consistent basis sets, it is seen that for larger penalties, the virtual orbitals become more local than the occupied ones. We also show that the local virtual HF orbitals are significantly more local than the redundant projected atomic orbitals, which often have been used to span the virtual...

Evaluation of use of MPAD trajectory tape and number of orbit points for orbiter mission thermal predictions

Science.gov (United States)

Vogt, R. A.

1979-01-01

The application of using the mission planning and analysis division (MPAD) common format trajectory data tape to predict temperatures for preflight and post flight mission analysis is presented and evaluated. All of the analyses utilized the latest Space Transportation System 1 flight (STS-1) MPAD trajectory tape, and the simplified '136 note' midsection/payload bay thermal math model. For the first 6.7 hours of the STS-1 flight profile, transient temperatures are presented for selected nodal locations with the current standard method, and the trajectory tape method. Whether the differences are considered significant or not depends upon the view point. Other transient temperature predictions are also presented. These results were obtained to investigate an initial concern that perhaps the predicted temperature differences between the two methods would not only be caused by the inaccuracies of the current method's assumed nominal attitude profile but also be affected by a lack of a sufficient number of orbit points in the current method. Comparison between 6, 12, and 24 orbit point parameters showed a surprising insensitivity to the number of orbit points.

Evaluation and analysis of real-time precise orbits and clocks products from different IGS analysis centers

Science.gov (United States)

Zhang, Liang; Yang, Hongzhou; Gao, Yang; Yao, Yibin; Xu, Chaoqian

2018-06-01

To meet the increasing demands from the real-time Precise Point Positioning (PPP) users, the real-time satellite orbit and clock products are generated by different International GNSS Service (IGS) real-time analysis centers and can be publicly received through the Internet. Based on different data sources and processing strategies, the real-time products from different analysis centers therefore differ in availability and accuracy. The main objective of this paper is to evaluate availability and accuracy of different real-time products and their effects on real-time PPP. A total of nine commonly used Real-Time Service (RTS) products, namely IGS01, IGS03, CLK01, CLK15, CLK22, CLK52, CLK70, CLK81 and CLK90, will be evaluated in this paper. Because not all RTS products support multi-GNSS, only GPS products are analyzed in this paper. Firstly, the availability of all RTS products is analyzed in two levels. The first level is the epoch availability, indicating whether there is outage for that epoch. The second level is the satellite availability, which defines the available satellite number for each epoch. Then the accuracy of different RTS products is investigated on nominal accuracy and the accuracy degradation over time. Results show that Root-Mean-Square Error (RMSE) of satellite orbit ranges from 3.8 cm to 7.5 cm for different RTS products. While the mean Standard Deviations of Errors (STDE) of satellite clocks range from 1.9 cm to 5.6 cm. The modified Signal In Space Range Error (SISRE) for all products are from 1.3 cm to 5.5 cm for different RTS products. The accuracy degradation of the orbit has the linear trend for all RTS products and the satellite clock degradation depends on the satellite clock types. The Rb clocks on board of GPS IIF satellites have the smallest degradation rate of less than 3 cm over 10 min while the Cs clocks on board of GPS IIF have the largest degradation rate of more than 10 cm over 10 min. Finally, the real-time kinematic PPP is

Research on orbit prediction for solar-based calibration proper satellite

Science.gov (United States)

Chen, Xuan; Qi, Wenwen; Xu, Peng

2018-03-01

Utilizing the mathematical model of the orbit mechanics, the orbit prediction is to forecast the space target's orbit information of a certain time based on the orbit of the initial moment. The proper satellite radiometric calibration and calibration orbit prediction process are introduced briefly. On the basis of the research of the calibration space position design method and the radiative transfer model, an orbit prediction method for proper satellite radiometric calibration is proposed to select the appropriate calibration arc for the remote sensor and to predict the orbit information of the proper satellite and the remote sensor. By analyzing the orbit constraint of the proper satellite calibration, the GF-1solar synchronous orbit is chose as the proper satellite orbit in order to simulate the calibration visible durance for different satellites to be calibrated. The results of simulation and analysis provide the basis for the improvement of the radiometric calibration accuracy of the satellite remote sensor, which lays the foundation for the high precision and high frequency radiometric calibration.

Titan Orbiter with Aerorover Mission (TOAM)

Science.gov (United States)

Sittler, Edward C.; Cooper, J. F.; Mahaffey, P.; Esper, J.; Fairbrother, D.; Farley, R.; Pitman, J.; Kojiro, D. R.; TOAM Team

2006-12-01

We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG 500 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan’s atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

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

Science.gov (United States)

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).

Orbital Dynamics of Low-Earth Orbit Laser-Propelled Space Vehicles

International Nuclear Information System (INIS)

Yamakawa, Hiroshi; Funaki, Ikkoh; Komurasaki, Kimiya

2008-01-01

Trajectories applicable to laser-propelled space vehicles with a laser station in low-Earth orbit are investigated. Laser vehicles are initially located in the vicinity of the Earth-orbiting laser station in low-earth orbit at an altitude of several hundreds kilometers, and are accelerated by laser beaming from the laser station. The laser-propelled vehicles start from low-earth orbit and finally escape from the Earth gravity well, enabling interplanetary trajectories and planetary exploration

Effect of lunar gravity models on Chang'E-2 orbit determination using VLBI tracking data

Directory of Open Access Journals (Sweden)

Erhu Wei

2016-11-01

Full Text Available The precise orbit determination of Chang'E-2 is the most important issue for successful mission and scientific applications, while the lunar gravity field model with big uncertainties has large effect on Chang'E-2 orbit determination. Recently, several new gravity models have been produced using the latest lunar satellites tracking data, such as LP165P, SGM150J, GL0900D and GRGM900C. In this paper, the four gravity models mentioned above were evaluated through the power spectra analysis, admittance and coherence analysis. Effect of four lunar gravity models on Chang'E-2 orbit determination performance is investigated and assessed using Very Long Baseline Interferometry (VLBI tracking data. The overlap orbit analysis, the posteriori data residual, and the orbit prediction are used to evaluate the orbit precision between successive arcs. The LP165P model has better orbit overlap performance than the SGM150J model for Chang'E-2100 km × 100 km orbit and the SGM150J model performs better for Chang'E-2100 km × 15 km orbit, while GL0900D and GRGM900C have the best orbit overlap results for the two types of Chang'E-2 orbit. For the orbit prediction, GRGM900C has the best orbit prediction performance in the four models.

XML Graphs in Program Analysis

DEFF Research Database (Denmark)

Møller, Anders; Schwartzbach, Michael I.

2011-01-01

of XML graphs against different XML schema languages, and provide a software package that enables others to make use of these ideas. We also survey the use of XML graphs for program analysis with four very different languages: XACT (XML in Java), Java Servlets (Web application programming), XSugar......XML graphs have shown to be a simple and effective formalism for representing sets of XML documents in program analysis. It has evolved through a six year period with variants tailored for a range of applications. We present a unified definition, outline the key properties including validation...

ExoMars Trace Gas Orbiter provides atmospheric data during Aerobraking into its final orbit

Science.gov (United States)

Svedhem, Hakan; Vago, Jorge L.; Bruinsma, Sean; Müller-Wodarg, Ingo; ExoMars 2016 Team

2017-10-01

After the arrival of the Trace Gas Orbiter (TGO) at Mars on 19 October 2016 a number of initial orbit change manoeuvres were executed and the spacecraft was put in an orbit with a 24 hour period and 74 degrees inclination. The spacecraft and its four instruments were thoroughly checked out after arrival and a few measurements and images were taken in November 2016 and in Feb-March 2017. The solar occultation observations have however not yet been possible due to lack of the proper geometry.On 15 March a long period of aerobraking to reach the final 400km semi-circular frozen orbit (370x430km, with a fixed pericentre latitude). This orbit is optimised for the payload observations and for the communication relay with the ExoMars Rover, due to arrive in 2021.The aerobraking is proceeding well and the final orbit is expected to be reached in April 2018. A large data set is being acquired for the upper atmosphere of Mars, from the limit of the sensitivity of the accelerometer, down to lowest altitude of the aerobraking at about 105km. Initial analysis has shown a highly variable atmosphere with a slightly lower density then predicted by existing models. Until the time of the abstract writing no dust storms have been observed.The ExoMars programme is a joint activity by the European Space Agency(ESA) and ROSCOSMOS, Russia. ESA is providing the TGO spacecraft and Schiaparelli (EDM) and two of the TGO instruments and ROSCOSMOS is providing the Proton launcher and the other two TGO instruments. After the arrival of the ExoMars 2020 mission, consisting of a Rover and a Surface platform also launched by a Proton rocket, the TGO will handle the communication between the Earth and the Rover and Surface Platform through its (NASA provided) UHF communication system.

Solution Method and Precision Analysis of Double-difference Dynamic Precise Orbit Determination of BeiDou Navigation Satellite System

Directory of Open Access Journals (Sweden)

LIU Weiping

2016-02-01

Full Text Available To resolve the high relativity between the transverse element of GEO orbit and double-difference ambiguity, the classical double-difference dynamic method is improved and the method, which is to determine precise BeiDou satellite orbit using carrier phase and pseudo-range smoothed by phase, is proposed. The feasibility of the method is discussed and the influence of the method about ambiguity fixing is analyzed. Considering the characteristic of BeiDou, the method, which is to fix double-difference ambiguity of BeiDou satellites by QIF, is derived. The real data analysis shows that the new method, which can reduce the relativity and assure the precision, is better than the classical double-difference dynamic method. The result of ambiguity fixing is well by QIF, but the ambiguity fixing success rate is not high on the whole. So the precision of BeiDou orbit can't be improved clearly after ambiguity fixing.

Stable orbits for lunar landing assistance

Science.gov (United States)

Condoleo, Ennio; Cinelli, Marco; Ortore, Emiliano; Circi, Christian

2017-10-01

To improve lunar landing performances in terms of mission costs, trajectory determination and visibility the use of a single probe located over an assistance orbit around the Moon has been taken into consideration. To this end, the properties of two quasi-circular orbits characterised by a stable behaviour of semi-major axis, eccentricity and inclination have been investigated. The analysis has demonstrated the possibility of using an assistance probe, located over one of these orbits, as a relay satellite between lander and Earth, even in the case of landings on the far side of the Moon. A comparison about the accuracy in retrieving the lander's state with respect to the use of a probe located in the Lagrangian point L2 of the Earth-Moon system has also been carried out.

CONGENITAL ORBITAL TERATOMA

African Journals Online (AJOL)

was done without contrast and 3mm/5mm/10mm slices were obtained to cover the orbit, skull base and brain. The findings included a soft tissue mass arising from the orbit. The left eye ball was extra orbital. There was no defect .... love's Short Practice of Surgery. 7 Edition,. Levis London, 1997; 45-64. 2. Orbital tumor Part 1, ...

Stress analysis program system for nuclear vessel: STANSAS

International Nuclear Information System (INIS)

Okamoto, Asao; Michikami, Shinsuke

1979-01-01

IHI has developed a computer system of stress analysis and evaluation for nuclear vessels: STANSAS (STress ANalysis System for Axi-symmetric Structure). The system consists of more than twenty independent programs divided into the following six parts. 1. Programs for opening design by code rule. 2. Calculation model generating programs. 3. Load defining programs. 4. Structural analysis programs. 5. Load data/calculation results plotting programs. 6. Stress evaluation programs. Each program is connected with its pre- or post-processor through three data-bases which enable automatic data transfer. The user can make his choice of structural analysis programs in accordance with the problem to be solved. The interface to STANSAS can be easily installed in generalized structural analysis programs such as NASTRAN and MARC. For almost all tables and figures in the stress report, STANSAS has the function to print or plot out. The complicated procedures of ''Design by Analysis'' for pressure vessels have been well standardized by STANSAS. The system will give a high degree of efficiency and confidence to the design work. (author)

DRAGONS-A Micrometeoroid and Orbital Debris Impact Sensor on the ISS

Science.gov (United States)

Liou, J.-C.; Hamilton, J.; Liolios, S.; Anderson, C.; Sadilek, A.; Corsaro, R.; Giovane, F.; Burchell, M.

2015-01-01

by the NASA Science Mission Directorate and the NASA Exploration Systems Mission Directorate, then by the NASA JSC Innovative Research and Development Program and the NASA Orbital Debris Program Office. The NASA Orbital Debris Program Office leads the effort with collaboration from the U.S. Naval Academy, Naval Research Laboratory, University of Kent at Canterbury in Great Britain, and Virginia Tech. The project recently reached a major milestone when DRAGONS was approved for a technology demonstration mission by the International Space Station (ISS) Program in October 2014. The plan is to deploy a 1 sq m DRAGONS on the ISS with the detection surface facing the ram-direction for 2 to 3 years. The tentative launch schedule is in early 2017. This mission will collect data on orbital debris in the sub-millimeter size regime to better define the small orbital debris environment at the ISS altitude. The mission will also advance the DRAGONS Technology Readiness Level to 9 and greatly enhance the opportunities to deploy DRAGONS on other spacecraft to high LEO orbits in the future.

Filament wound pressure vessels with load sharing liners for space shuttle orbiter applications

International Nuclear Information System (INIS)

Ecord, G.M.

1976-01-01

Early in the development of orbiter propulsion and environmental control subsystems it was recognized that use of overwrapped pressure vessels with load sharing liners may provide significant weight savings for high pressure gas containment. A program is described which was undertaken by Rockwell International to assess the utility for orbiter applications of titanium 6Al--4V and Inconel 718 liners overwrapped with Kevlar fibers. Also briefly described are programs administered by the NASA Lewis Research Center to evaluate cryoformed steel liners overwrapped with Kevlar fibers and to establish a method that can guarantee cyclic life of the vessels

Analysis of the Effect of UTI-UTC to High Precision Orbit Propagation

Directory of Open Access Journals (Sweden)

Dongseok Shin

1999-12-01

Full Text Available 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.

The Carter constant for inclined orbits about a massive Kerr black hole: I. Circular orbits

Energy Technology Data Exchange (ETDEWEB)

Komorowski, P G; Valluri, S R; Houde, M, E-mail: pkomorow@uwo.c, E-mail: valluri@uwo.c, E-mail: mhoude2@uwo.c [Department of Physics and Astronomy, University of Western Ontario, London, Ontario (Canada)

2010-11-21

In an extreme binary black hole system, an orbit will increase its angle of inclination ({iota}) as it evolves in Kerr spacetime. We focus our attention on the behaviour of the Carter constant (Q) for near-polar orbits, and develop an analysis that is independent of and complements radiation-reaction models. For a Schwarzschild black hole, the polar orbits represent the abutment between the prograde and retrograde orbits at which Q is at its maximum value for given values of the latus rectum ({tilde l}) and the eccentricity (e). The introduction of spin ({tilde S}={vert_bar}J{vert_bar}/M{sup 2}) to the massive black hole causes this boundary, or abutment, to be moved towards greater orbital inclination; thus, it no longer cleanly separates prograde and retrograde orbits. To characterize the abutment of a Kerr black hole (KBH), we first investigated the last stable orbit (LSO) of a test-particle about a KBH, and then extended this work to general orbits. To develop a better understanding of the evolution of Q we developed analytical formulae for Q in terms of {tilde l}, e and {tilde S} to describe elliptical orbits at the abutment, polar orbits and LSOs. By knowing the analytical form of {partial_derivative}Q/{partial_derivative}{tilde l} at the abutment, we were able to test a 2PN flux equation for Q. We also used these formulae to numerically calculate the {partial_derivative}{iota}/{partial_derivative}{tilde l} of hypothetical circular orbits that evolve along the abutment. From these values we have determined that {partial_derivative}{iota}/{partial_derivative}{tilde l} = -(122.7{tilde S} - 36{tilde S}{sup 3}){tilde l}{sup -11/2} - (63/2 {tilde S} + 35/4 {tilde S}{sup 3}){tilde l}{sup -9/2} - 15/2 {tilde S}{tilde l}{sup -7/2} - 9/2 {tilde S}{tilde l}{sup -5/2}. By taking the limit of this equation for {tilde l} {yields} {infinity}, and comparing it with the published result for the weak-field radiation reaction, we found the upper limit on

A hybrid numerical method for orbit correction

International Nuclear Information System (INIS)

White, G.; Himel, T.; Shoaee, H.

1997-09-01

The authors describe a simple hybrid numerical method for beam orbit correction in particle accelerators. The method overcomes both degeneracy in the linear system being solved and respects boundaries on the solution. It uses the Singular Value Decomposition (SVD) to find and remove the null-space in the system, followed by a bounded Linear Least Squares analysis of the remaining recast problem. It was developed for correcting orbit and dispersion in the B-factory rings

Rendezvous terminal phase automatic braking sequencing and targeting. [for space shuttle orbiter

Science.gov (United States)

Kachmar, P. M.

1973-01-01

The purpose of the rendezvous terminal phase braking program is to provide the means of automatically bringing the primary orbiter within desired station keeping boundaries relative to the target satellite. A detailed discussion is presented on the braking program and its navigation, targeting, and guidance functions.

Status of Precise Orbit Determination for Jason-2 Using GPS

Science.gov (United States)

Melachroinos, S.; Lemoine, F. G.; Zelensky, N. P.; Rowlands, D. D.; Pavlis, D. E.

2011-01-01

The JASON-2 satellite, launched in June 2008, is the latest follow-on to the successful TOPEX/Poseidon (T/P) and JASON-I altimetry missions. JASON-2 is equipped with a TRSR Blackjack GPS dual-frequency receiver, a laser retroreflector array, and a DORIS receiver for precise orbit determination (POD). The most recent time series of orbits computed at NASA GSFC, based on SLR/DORIS data have been completed using both ITRF2005 and ITRF2008. These orbits have been shown to agree radially at 1 cm RMS for dynamic vs SLRlDORIS reduced-dynamic orbits and in comparison with orbits produced by other analysis centers (Lemoine et al., 2010; Zelensky et al., 2010; Cerri et al., 2010). We have recently upgraded the GEODYN software to implement model improvements for GPS processing. We describe the implementation of IGS standards to the Jason2 GEODYN GPS processing, and other dynamical and measurement model improvements. 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 and the altimeter crossover residuals provide the best performance indicator for independent validation of the NASAlGSFC GPS-only reduced dynamic orbits. For the ITRF2005 and ITRF2008 implementation of our GPS-only obits we are using the IGS05 and IGS08 standards. Reduced dynamic versus dynamic orbit differences are used to characterize the remaining force model error and TRF instability. We evaluate the GPS vs SLR & DORIS orbits produced using the GEODYN software and assess in particular their consistency radially and the stability of the altimeter satellite reference frame in the Z direction for both ITRF2005 and ITRF2008 as a proxy to assess the consistency of the reference frame for altimeter satellite POD.

Radiovolumetry of the orbit

International Nuclear Information System (INIS)

Abujamra, S.

1983-01-01

The authors present a method called ''Radiovolumetry of the orbit'' that permits the evaluation of the orbital volume from anteroposterior skull X-Rays (CALDWELL 30 0 position). The research was based in the determination of the orbital volume with lead spheres, in 1010 orbits of 505 dry skulls of Anatomy Museums. After the dry skulls was X-rayed six frontal orbital diameters were made, with care to correct the radiographic amplification. PEARSON correlation coeficient test was applied between the mean orbital diameter and the orbital volume. The result was r = 0,8 with P [pt

Detailed Wave Function Analysis for Multireference Methods: Implementation in the Molcas Program Package and Applications to Tetracene.

Science.gov (United States)

Plasser, Felix; Mewes, Stefanie A; Dreuw, Andreas; González, Leticia

2017-11-14

High-level multireference computations on electronically excited and charged states of tetracene are performed, and the results are analyzed using an extensive wave function analysis toolbox that has been newly implemented in the Molcas program package. Aside from verifying the strong effect of dynamic correlation, this study reveals an unexpected critical influence of the atomic orbital basis set. It is shown that different polarized double-ζ basis sets produce significantly different results for energies, densities, and overall wave functions, with the best performance obtained for the atomic natural orbital (ANO) basis set by Pierloot et al. Strikingly, the ANO basis set not only reproduces the energies but also performs exceptionally well in terms of describing the diffuseness of the different states and of their attachment/detachment densities. This study, thus, not only underlines the fact that diffuse basis functions are needed for an accurate description of the electronic wave functions but also shows that, at least for the present example, it is enough to include them implicitly in the contraction scheme.

Use of the neighboring orbital model for analysis of electronic coupling in Class III intervalence compounds

International Nuclear Information System (INIS)

Nelsen, Stephen F.; Weaver, Michael N.; Luo Yun; Lockard, Jenny V.; Zink, Jeffrey I.

2006-01-01

Symmetrical charge-delocalized intervalence radical ions should not be described by the traditional two-state model that has been so successful for their localized counterparts. If they lack direct overlap between their charge-bearing units (M), their diabatic orbitals have an equal energy pair of symmetrized M-centered combination orbitals that are symmetric (S) or antisymmetric (A) with respect to a symmetry element at the center of the molecule. The M combination orbitals will mix separately with bridge orbitals of the same symmetry. We call the simplest useful model for this situation the neighboring orbital model, which uses the S and A bridge orbitals of high overlap that lie closest in energy to the M orbital pair, resulting in two two-state models that have a common energy for one pair. This model is developed quantitatively, and examples having 1, 3, 5, and 7 electrons in the neighboring orbitals are illustrated

Quantum mechanical analysis of fractal conductance fluctuations: a picture using self-similar periodic orbits

International Nuclear Information System (INIS)

Ogura, Tatsuo; Miyamoto, Masanori; Budiyono, Agung; Nakamura, Katsuhiro

2007-01-01

Fractal magnetoconductance fluctuations are often observed in experiments on ballistic quantum dots. Although the analysis of the exact self-affine fractal has been given by the semiclassical theory using self-similar periodic orbits in systems with a soft-walled potential with a saddle, there has been no corresponding quantum mechanical investigation. We numerically calculate the quantum conductance with use of the recursive Green's function method applied to open cavities characterized by a Henon-Heiles type potential. The conductance fluctuations show exact self-affinity just as in some of the experimental observations. The enlargement factor for the horizontal axis can be explained by the scaling factor of the area of self-similar periodic orbits, and therefore be attributed to the curvature of the saddle in the cavity potential. The fractal dimension obtained through the box counting method agrees with those evaluated with use of the Hurst exponent, and coincides with the semiclassical prediction. We further investigate the variation of the fractal dimension by changing the control parameters between the classical and quantum domains. (fast track communication)

Independent Orbiter Assessment (IOA): Assessment of the orbiter main propulsion system FMEA/CIL, volume 1

Science.gov (United States)

Slaughter, B. C.

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 effort first completed an analysis of the Main Propulsion System (MPS) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to available data from the Rockwell Downey/NASA JSC FMEA/CIL review. The Orbiter MPS is composed of the Propellant Management Subsystem (PMS) consisting of the liquid oxygen (LO2) and liquid hydrogen (LH2) subsystems 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 to the Space Shuttle Main Engine (SSME). The helium subsystem consists of a series of helium supply tanks and their associated regulators, control valves, and distribution lines. Volume 1 contains the MPS description, assessment results, ground rules and assumptions, and some of the IOA worksheets.

Energy Analysis Program 1990 annual report

Energy Technology Data Exchange (ETDEWEB)

1992-01-01

The Energy Analysis Program has played an active role in the analysis and discussion of energy and environmental issues at several levels. (1) at the international level, with programs as developing scenarios for long-term energy demand in developing countries and organizing leading an analytic effort, ``Energy Efficiency, Developing Countries, and Eastern Europe,`` part of a major effort to increase support for energy efficiency programs worldwide; (2) at national level, the Program has been responsible for assessing energy forecasts and policies affecting energy use (e.g., appliance standards, National Energy Strategy scenarios); and (3) at the state and utility levels, the Program has been a leader in promoting integrated resource utility planning; the collaborative process has led to agreement on a new generation of utility demand-site programs in California, providing an opportunity to use knowledge and analytic techniques of the Program`s researchers. We continue to place highest on analyzing energy efficiency, with particular attention given to energy use in buildings. The Program continues its active analysis of international energy issues in Asia (including China), the Soviet Union, South America, and Western Europe. Analyzing the costs and benefits of different levels of standards for residential appliances continues to be the largest single area of research within the Program. The group has developed and applied techniques for forecasting energy demand (or constructing scenarios) for the United States. We have built a new model of industrial energy demand, are in the process of making major changes in our tools for forecasting residential energy demand, have built an extensive and documented energy conservation supply curve of residential energy use, and are beginning an analysis of energy-demand forecasting for commercial buildings.

Conducting a SWOT Analysis for Program Improvement

Science.gov (United States)

Orr, Betsy

2013-01-01

A SWOT (strengths, weaknesses, opportunities, and threats) analysis of a teacher education program, or any program, can be the driving force for implementing change. A SWOT analysis is used to assist faculty in initiating meaningful change in a program and to use the data for program improvement. This tool is useful in any undergraduate or degree…

Kinematic Orbit Determination Method Optimization and Test Analysis for BDS Satellites with Short-arc Tracking Data

Directory of Open Access Journals (Sweden)

GUO Rui

2017-04-01

Full Text Available Rapid orbit recovery is a puzzle for the BDS satellites after orbit maneuvers. Two kinematic orbit determination methods are studied, with two orbit determination models being established. The receiver system error and serious multipath error exist in the BDS system. The co-location method is proposed to estimate and calibrate the receiver system errors. A CNMC (code noise and multipath correction method is introduced to weaken the multipath error. Therefore the data quality is controlled efficiently for the receivers in the short tracking arc. The GEO/IGSO/MEO real data is emploied to carry out tests and validation. Using 10 min short tracking arc, the kinematic precise orbit determination accuracy is about 3.27 m for the GEOs, and 8.19 m for the IGSOs, and 5.9 m for the MEOs. Rapid orbit determination is achieved, which satisfying the orbit requirements from the BDS RDSS services. The kinematic precise orbit determination method also supports the RDSS service walking up to the global world.

Solar Effects of Low-Earth Orbit objects in ORDEM 3.0

Science.gov (United States)

Vavrin, A. B.; Anz-Meador, P.; Kelley, R. L.

2014-01-01

Variances in atmospheric density are directly related to the variances in solar flux intensity between 11- year solar cycles. The Orbital Debris Engineering Model (ORDEM 3.0) uses a solar flux table as input for calculating orbital lifetime of intact and debris objects in Low-Earth Orbit. Long term projections in solar flux activity developed by the NASA Orbital Debris Program Office (ODPO) extend the National Oceanic and Atmospheric Administration Space Environment Center (NOAA/SEC) daily historical flux values with a 5-year projection. For purposes of programmatic scheduling, the Q2 2009 solar flux table was chosen for ORDEM 3.0. Current solar flux activity shows that the current solar cycle has entered a period of lower solar flux intensity than previously forecasted in 2009. This results in a deviation of the true orbital debris environment propagation in ORDEM 3.0. In this paper, we present updated orbital debris populations in LEO using the latest solar flux values. We discuss the effects on recent breakup events such as the FY-1C anti-satellite test and the Iridium 33 / Cosmos 2251 accidental collision. Justifications for chosen solar flux tables are discussed.

Orbital wall fractures

International Nuclear Information System (INIS)

Iinuma, Toshitaka; Ishio, Ken-ichirou; Yoshinami, Hiroyoshi; Kuriyama, Jun-ichi; Hirota, Yoshiharu.

1993-01-01

A total of 59 cases of mild facial fractures (simple orbital wall fractures, 34 cases, other facial fractures, 25 cases) with the clinical suspects of orbital wall fractures were evaluated both by conventional views (Waters' and Caldwell views) and coronal CT scans. Conventional views were obtained, as an average, after 4 days and CT after 7 days of injuries. Both the medial wall and the floor were evaluated at two sites, i.e., anterior and posterior. The ethmoid-maxillary plate was also included in the study. The degree of fractures was classified as, no fractures, fractures of discontinuity, dislocation and fragmentation. The coronal CT images in bone window condition was used as reference and the findings were compared between conventional views and CT. The correct diagnosis was obtained as follows: orbital floor (anterior, 78%, posterior, 73%), medial orbital wall (anterior, 72%, posterior, 72%) and ethmoid-maxillary plate (64%). The false positive diagnosis was as follows: orbital floor (anterior only, 13%), medial orbital wall (anterior only, 7%) and ethmoid-maxillary plate (11%). The false negative diagnosis was as follows: orbital floor (anterior, 9%, posterior, 10%), medial orbital wall (anterior, 21%, posterior, 28%) and ethmoid-maxillary plate (21%). The results were compared with those of others in the past. (author)

A computer program for activation analysis

International Nuclear Information System (INIS)

Rantanen, J.; Rosenberg, R.J.

1983-01-01

A computer program for calculating the results of activation analysis is described. The program comprises two gamma spectrum analysis programs, STOAV and SAMPO and one program for calculating elemental concentrations, KVANT. STOAV is based on a simple summation of channels and SAMPO is based on fitting of mathematical functions. The programs are tested by analyzing the IAEA G-1 test spectra. In the determination of peak location SAMPO is somewhat better than STOAV and in the determination of peak area SAMPO is more than twice as accurate as STOAV. On the other hand, SAMPO is three times as expensive as STOAV with the use of a Cyber 170 computer. (author)

Natural bond orbital analysis of molecular interactions: Theoretical study of W(CO)5 complexes with E(PH3)2 and NHEMe ligands (E=C, Si, Ge, Sn, Pb)

International Nuclear Information System (INIS)

Nguyen Thi Ai Nhung; Huynh Thi Phuong Loan; Duong Tuan Quang; Pham Van Tat

2014-01-01

The complexes with ligands carbodiphosphorane-analogues (called tetrylones) [(CO) 5 W-{E(PH 3 ) 2 }] (W5-EP 2 ) and N-heterocyclic carbene-analogues (called tetrylenes) [(CO) 5 W-{NHE Me }] (W5-NHE Me ) when E=C-Pb have been studied using natural bond orbital (NBO) method. The NBO analysis provides a consistent picture of the chemical bonding is two entire families of transition metal complexes of tetrylone and tetrylene ligands in term of donor-acceptor interactions, showing the correlation of these interactions with Wiberg bond indies (WBI), natural partial charges, and the energetically highest lying occupied molecular orbitals for σ and π orbitals of free ligands E(PH 3 ) 2 and NHE Me . Analysis of the bonding situation reveals that in E(PH 3 ) 2 and NHE Me ligands, the energy level of the π orbital rises, whereas that of the σ orbital decreases as atom E becomes heavier. The complexes with head-on-bonded ligands have (CO) 5 W←E donation which comes from the σ-lone-pair orbital of E(PH 3 ) 2 and NHE Me where E=C for tetrylones and E=C, Si, Ge for tetrylenes, whereas the (CO) 5 W←E donation in the side-on bonded complexes when E becomes heavier arises from the π-lone-pair orbital of E(PH 3 ) 2 and NHE Me ligands which is the HOMO of the free ligands. This makes the heavier adducts of tetrylones and tetrylenes become stronger donors than the lighter systems. The NBO analysis suggests that the E(PH 3 ) 2 ligands are strong σ-donors and strong π-acceptors while the NHE Me ligands are strong σ-donors and weak π-acceptors. This is possible for tetrylones that have two lone-pair orbitals available for donation, whereas the tetrylenes have only one lone-pair orbital available for donation. (author)

Probabilistic Output Analysis by Program Manipulation

DEFF Research Database (Denmark)

Rosendahl, Mads; Kirkeby, Maja Hanne

2015-01-01

The aim of a probabilistic output analysis is to derive a probability distribution of possible output values for a program from a probability distribution of its input. We present a method for performing static output analysis, based on program transformation techniques. It generates a probability...

Space shuttle orbital maneuvering engine platelet injector program

Science.gov (United States)

1975-01-01

A platelet-face injector for the fully reusable orbit maneuvering system OMS on the space shuttle was evaluated as a means of obtaining additional design margin and low cost. Performance, heat transfer, and combustion stability were evaluated over the anticipated range of OMS operating conditions. The effects of acoustic cavity configuration on combustion stability, including cavity depth, open area, inlet contour, and other parameters, were investigated using sea level bomb tests. Prototype injector and chamber behavior was evaluated for a variety of conditions; these tests examined the effects of film cooling, helium saturated propellants, chamber length, inlet conditions, and operating point, on performance, heat transfer and engine transient behavior. Helium bubble ingestion into both propellant circuits was investigated, as was chugging at low pressure operation, and hot and cold engine restart with and without a purge.

In-Flight Operation of the Dawn Ion Propulsion System Through Survey Science Orbit at Ceres

Science.gov (United States)

Garner, Charles E.; Rayman, Marc D.

2015-01-01

The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt objects, Vesta and Ceres. The Dawn spacecraft was launched from the Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H- 9.5 (Delta-II Heavy) rocket that placed the 1218-kg spacecraft onto an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide a total delta V of 11 km/s for the heliocentric transfer to Vesta, orbit capture at Vesta, transfer between Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer between Ceres science orbits. Full-power thrusting from December 2007 through October 2008 was used to successfully target a Mars gravity assist flyby in February 2009 that provided an additional delta V of 2.6 km/s. Deterministic thrusting for the heliocentric transfer to Vesta resumed in June 2009 and concluded with orbit capture at Vesta on July 16, 2011. From July 2011 through September 2012 the IPS was used to transfer to all the different science orbits at Vesta and to escape from Vesta orbit. Cruise for a rendezvous with Ceres began in September 2012 and concluded with the start of the approach to Ceres phase on December 26, 2015, leading to orbit capture on March 6, 2015. Deterministic thrusting continued during approach to place the spacecraft in its first science orbit, called RC3, which was achieved on April 23, 2015. Following science operations at RC3 ion thrusting was resumed for twenty-five days leading to arrival to the next science orbit, called survey orbit, on June 3, 2015. The IPS will be used for all subsequent orbit transfers and trajectory correction maneuvers until completion of the primary mission in approximately June 2016. To date the IPS has been operated for over 46,774 hours, consumed approximately 393 kg of xenon, and provided

Fragment-orbital tunneling currents and electronic couplings for analysis of molecular charge-transfer systems.

Science.gov (United States)

Hwang, Sang-Yeon; Kim, Jaewook; Kim, Woo Youn

2018-04-04

In theoretical charge-transfer research, calculation of the electronic coupling element is crucial for examining the degree of the electronic donor-acceptor interaction. The tunneling current (TC), representing the magnitudes and directions of electron flow, provides a way of evaluating electronic couplings, along with the ability of visualizing how electrons flow in systems. Here, we applied the TC theory to π-conjugated organic dimer systems, in the form of our fragment-orbital tunneling current (FOTC) method, which uses the frontier molecular-orbitals of system fragments as diabatic states. For a comprehensive test of FOTC, we assessed how reasonable the computed electronic couplings and the corresponding TC densities are for the hole- and electron-transfer databases HAB11 and HAB7. FOTC gave 12.5% mean relative unsigned error with regard to the high-level ab initio reference. The shown performance is comparable with that of fragment-orbital density functional theory, which gave the same error by 20.6% or 13.9% depending on the formulation. In the test of a set of nucleobase π stacks, we showed that the original TC expression is also applicable to nondegenerate cases under the condition that the overlap between the charge distributions of diabatic states is small enough to offset the energy difference. Lastly, we carried out visual analysis on the FOTC densities of thiophene dimers with different intermolecular alignments. The result depicts an intimate topological connection between the system geometry and electron flow. Our work provides quantitative and qualitative grounds for FOTC, showing it to be a versatile tool in characterization of molecular charge-transfer systems.

Nonlinear programming analysis and methods

CERN Document Server

Avriel, Mordecai

2012-01-01

This text provides an excellent bridge between principal theories and concepts and their practical implementation. Topics include convex programming, duality, generalized convexity, analysis of selected nonlinear programs, techniques for numerical solutions, and unconstrained optimization methods.

Charge-spin-orbital dynamics of one-dimensional two-orbital Hubbard model

Energy Technology Data Exchange (ETDEWEB)

Onishi, Hiroaki [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

2010-01-15

We study the real-time evolution of a charge-excited state in a one-dimensional e{sub g}-orbital degenerate Hubbard model, by a time-dependent density-matrix renormalization group method. Considering a chain along the z direction, electrons hop between adjacent 3z{sup 2}-r{sup 2} orbitals, while x{sup 2}-y{sup 2} orbitals are localized. For the charge-excited state, a holon-doublon pair is introduced into the ground state at quarter filling. At initial time, there is no electron in a holon site, while a pair of electrons occupies 3z{sup 2}-r{sup 2} orbital in a doublon site. As the time evolves, the holon motion is governed by the nearest-neighbor hopping, but the electron pair can transfer between 3z{sup 2}-r{sup 2} orbital and x{sup 2}-y{sup 2} orbital through the pair hopping in addition to the nearest-neighbor hopping. Thus holon and doublon propagate at different speed due to the pair hopping that is characteristic of multi-orbital systems.

The world state of orbital debris measurements and modeling

Science.gov (United States)

Johnson, Nicholas L.

2004-02-01

For more than 20 years orbital debris research around the world has been striving to obtain a sharper, more comprehensive picture of the near-Earth artificial satellite environment. Whereas significant progress has been achieved through better organized and funded programs and with the assistance of advancing technologies in both space surveillance sensors and computational capabilities, the potential of measurements and modeling of orbital debris has yet to be realized. Greater emphasis on a systems-level approach to the characterization and projection of the orbital debris environment would prove beneficial. On-going space surveillance activities, primarily from terrestrial-based facilities, are narrowing the uncertainties of the orbital debris population for objects greater than 2 mm in LEO and offer a better understanding of the GEO regime down to 10 cm diameter objects. In situ data collected in LEO is limited to a narrow range of altitudes and should be employed with great care. Orbital debris modeling efforts should place high priority on improving model fidelity, on clearly and completely delineating assumptions and simplifications, and on more thorough sensitivity studies. Most importantly, however, greater communications and cooperation between the measurements and modeling communities are essential for the efficient advancement of the field. The advent of the Inter-Agency Space Debris Coordination Committee (IADC) in 1993 has facilitated this exchange of data and modeling techniques. A joint goal of these communities should be the identification of new sources of orbital debris.

Orbital stability of solitary waves for Kundu equation

Science.gov (United States)

Zhang, Weiguo; Qin, Yinghao; Zhao, Yan; Guo, Boling

In this paper, we consider the Kundu equation which is not a standard Hamiltonian system. The abstract orbital stability theory proposed by Grillakis et al. (1987, 1990) cannot be applied directly to study orbital stability of solitary waves for this equation. Motivated by the idea of Guo and Wu (1995), we construct three invariants of motion and use detailed spectral analysis to obtain orbital stability of solitary waves for Kundu equation. Since Kundu equation is more complex than the derivative Schrödinger equation, we utilize some techniques to overcome some difficulties in this paper. It should be pointed out that the results obtained in this paper are more general than those obtained by Guo and Wu (1995). We present a sufficient condition under which solitary waves are orbitally stable for 2c+sυ1995) only considered the case 2c+sυ>0. We obtain the results on orbital stability of solitary waves for the derivative Schrödinger equation given by Colin and Ohta (2006) as a corollary in this paper. Furthermore, we obtain orbital stability of solitary waves for Chen-Lee-Lin equation and Gerdjikov-Ivanov equation, respectively.

On-Orbit Solar Dynamics Observatory (SDO) Star Tracker Warm Pixel Analysis

Science.gov (United States)

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

Energy Analysis Program 1990 annual report

International Nuclear Information System (INIS)

1992-01-01

The Energy Analysis Program has played an active role in the analysis and discussion of energy and environmental issues at several levels. (1) at the international level, with programs as developing scenarios for long-term energy demand in developing countries and organizing leading an analytic effort, ''Energy Efficiency, Developing Countries, and Eastern Europe,'' part of a major effort to increase support for energy efficiency programs worldwide; (2) at national level, the Program has been responsible for assessing energy forecasts and policies affecting energy use (e.g., appliance standards, National Energy Strategy scenarios); and (3) at the state and utility levels, the Program has been a leader in promoting integrated resource utility planning; the collaborative process has led to agreement on a new generation of utility demand-site programs in California, providing an opportunity to use knowledge and analytic techniques of the Program's researchers. We continue to place highest on analyzing energy efficiency, with particular attention given to energy use in buildings. The Program continues its active analysis of international energy issues in Asia (including China), the Soviet Union, South America, and Western Europe. Analyzing the costs and benefits of different levels of standards for residential appliances continues to be the largest single area of research within the Program. The group has developed and applied techniques for forecasting energy demand (or constructing scenarios) for the United States. We have built a new model of industrial energy demand, are in the process of making major changes in our tools for forecasting residential energy demand, have built an extensive and documented energy conservation supply curve of residential energy use, and are beginning an analysis of energy-demand forecasting for commercial buildings

Depolarization of the electron spin in storage rings by nonlinear spin-orbit coupling

International Nuclear Information System (INIS)

Kewisch, J.

1985-10-01

Electrons and positrons which circulate in the storage ring are polarized at the emission of synchrotron radiation by the so called Sokolov-Ternov effect. This polarization is on the one hand of large interest for the study of the weak interaction, on the other hand it can be used for the accurate measurement of the beam energy and by this of the mass of elementary particles. The transverse and longitudinal particle vibrations simultaneously excited by the synchrotron radiation however can effect that this polarization is destroyed. This effect is called spin-orbit coupling. For the calculation of the spin-orbit coupling the computer program SITROS was written. This program is a tracking program: The motion of some sample particles and their spin vectors are calculated for some thousand circulations. From this the mean depolarization and by extrapolation the degree of polarization of the equilibrium state is determined. Contrarily to the known program SLIM which is based on perturbational calculations in SITROS the nonlinear forces in the storage ring can be regarded. By this the calculation of depolarizing higher order resonances is made possible. In this thesis the equations of motion for the orbital and spin motion of the electrons are derived which form the base for the program SITROS. The functions of the program and the approximations necessary for the saving of calculational time are explained. The comparison of the SITROS results with the measurement results obtained at the PETRA storage ring shows that the SITROS program is a useful means for the planning and calculation of storage rings with polarized electron beams. (orig.) [de

Two impulse trajectory optimization for the RAE-B orbit trim problem

Science.gov (United States)

Payne, M. H.; Pines, S.; Horsewood, J. L.

1972-01-01

The results are reported of work on an appropriate approach to the solution of the optimum two-impulse transfer problem between orbits of specified inclination. The task included a literature search to identify the current state of the art and a definition of the suggested approach for the specific application of a lunar orbit trim. The applications of the results to the problem are included. The formulation for a computer program developed under this task following a more conventional approach is also included.

Spacecraft design project: Low Earth orbit communications satellite

Science.gov (United States)

Moroney, Dave; Lashbrook, Dave; Mckibben, Barry; Gardener, Nigel; Rivers, Thane; Nottingham, Greg; Golden, Bill; Barfield, Bill; Bruening, Joe; Wood, Dave

1991-01-01

This is the final product of the spacecraft design project completed to fulfill the academic requirements of the Spacecraft Design and Integration 2 course (AE-4871) taught at the U.S. Naval Postgraduate School. The Spacecraft Design and Integration 2 course is intended to provide students detailed design experience in selection and design of both satellite system and subsystem components, and their location and integration into a final spacecraft configuration. The design team pursued a design to support a Low Earth Orbiting (LEO) communications system (GLOBALSTAR) currently under development by the Loral Cellular Systems Corporation. Each of the 14 team members was assigned both primary and secondary duties in program management or system design. Hardware selection, spacecraft component design, analysis, and integration were accomplished within the constraints imposed by the 11 week academic schedule and the available design facilities.

Earth Observatory Satellite system definition study. Report 1: Orbit/launch vehicle trade-off studies and recommendations

Science.gov (United States)

1974-01-01

A summary of the constraints and requirements on the Earth Observatory Satellite (EOS-A) orbit and launch vehicle analysis is presented. The propulsion system (hydrazine) and the launch vehicle (Delta 2910) selected for EOS-A are examined. The rationale for the selection of the recommended orbital altitude of 418 nautical miles is explained. The original analysis was based on the EOS-A mission with the Thematic Mapper and the High Resolution Pointable Imager. The impact of the revised mission model is analyzed to show how the new mission model affects the previously defined propulsion system, launch vehicle, and orbit. A table is provided to show all aspects of the EOS multiple mission concepts. The subjects considered include the following: (1) mission orbit analysis, (2) spacecraft parametric performance analysis, (3) launch system performance analysis, and (4) orbits/launch vehicle selection.

Analysis of computer programming languages

International Nuclear Information System (INIS)

Risset, Claude Alain

1967-01-01

This research thesis aims at trying to identify some methods of syntax analysis which can be used for computer programming languages while putting aside computer devices which influence the choice of the programming language and methods of analysis and compilation. In a first part, the author proposes attempts of formalization of Chomsky grammar languages. In a second part, he studies analytical grammars, and then studies a compiler or analytic grammar for the Fortran language

Analysis of the volumetric relationship among human ocular, orbital and fronto-occipital cortical morphology

Science.gov (United States)

Masters, Michael; Bruner, Emiliano; Queer, Sarah; Traynor, Sarah; Senjem, Jess

2015-01-01

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

Analysis of the volumetric relationship among human ocular, orbital and fronto-occipital cortical morphology.

Science.gov (United States)

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

The nuclear spin-orbit coupling

International Nuclear Information System (INIS)

Bell, J.S.; Skyrme, T.H.R.

1994-01-01

Analysis of the nucleon-nucleon scattering around 100 MeV has determined the spin-orbit coupling part of the two-body scattering matrix at that energy, and a reasonable extrapolation to lower energies is possible. This scattering amplitude has been used, in the spirit of Brueckner's nuclear model, to estimate the resultant single-body spin-orbit coupling for a single nucleon interacting with a large nucleus. This resultant potential has a radial dependence approximately proportional to r -1 d ρ /dr, and with a magnitude in good agreement with that required to explain the doublet splittings in nuclei and the polarization of nucleons scattered elastically off nuclei. (author). 14 refs, 2 figs

SeaWiFS technical report series. Volume 11: Analysis of selected orbit propagation models for the SeaWiFS mission

Science.gov (United States)

Patt, Frederick S.; Hoisington, Charles M.; Gregg, Watson W.; Coronado, Patrick L.; Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Indest, A. W. (Editor)

1993-01-01

An analysis of orbit propagation models was performed by the Mission Operations element of the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) Project, which has overall responsibility for the instrument scheduling. The orbit propagators selected for this analysis are widely available general perturbations models. The analysis includes both absolute accuracy determination and comparisons of different versions of the models. The results show that all of the models tested meet accuracy requirements for scheduling and data acquisition purposes. For internal Project use the SGP4 propagator, developed by the North American Air Defense (NORAD) Command, has been selected. This model includes atmospheric drag effects and, therefore, provides better accuracy. For High Resolution Picture Transmission (HRPT) ground stations, which have less stringent accuracy requirements, the publicly available Brouwer-Lyddane models are recommended. The SeaWiFS Project will make available portable source code for a version of this model developed by the Data Capture Facility (DCF).

Orbital frustration induced unusual ordering in semiconductor alloys

Science.gov (United States)

Liu, Kai; Yin, Wanjian; Chen, Shiyou; Gong, Xingao; Wei, Suhuai; Xiang, Hongjun

It is well known that ternary zinc-blende semiconductors are always more stable in the chalcopyrite (CH) structure than the Cu-Au (CA) structure because CH structure has large Coulomb interaction and reduced strain energy. Surprisingly, an experimental study showed that ZnFeSe2 alloy takes the CA order as the ground state structure, which is consistent with our density function theory (DFT) calculations showing that the CA order has lower energy than the CH order for ZnFeSe2. We reveal that the orbital degree of freedom of high-spin Fe2+ ion (d6) in the tetrahedral crystal field plays a key role in stabilizing the CA order. First, the spin-minority d electron of the Fe2+ ion tends to occupy the dx2-y 2 -like orbital instead of the d3z2 -r2 -like orbital because of its large negative Coulomb energy. Second, for a nearest-neighboring Fe2+ pair, two spin-minority d electrons with occupied dx2-y 2 -like orbitals in the plane containing the Fe-Fe bond has lower electronic kinetic energy. Both conditions can be satisfied in the CA ordered ZnFeSe2 alloy, while there is an orbital frustration in the CH structure. Our results suggest that orbital degree of freedom provides a new way to manipulate the structure and properties of alloys. Work at Fudan was supported by NSFC (11374056), the Special Funds for Major State Basic Research (2012CB921400, 2015CB921700), Program for Professor of Special Appointment (Eastern Scholar), and Fok Ying Tung Education Foundation.

Wuhan University Deep-space Orbit Determination and Gravity Recovery System(WUDOGS and Its Application Analysis

Directory of Open Access Journals (Sweden)

YE Mao

2017-03-01

Full Text Available WUDOGS(Wuhan University deep-space orbit determination and gravity recovery system is a software system designed for deep spacecraft precise orbit determination and planetary gravity recovery, developed independently at Wuhan University. WUDOGS now has the function for Lunar and Mars spacecraft precision orbit determination. Its design pattern and main function are briefly introduced. The cross verification test(CVT between WUDOGS and state of the art planetary precise orbit determination software GEODYN-Ⅱ are elaborated. The results show that:①for orbit propagation, with all the same forces and other configuration, the predicted orbit difference in R,T,N directions are less than 0.3 mm for one month arc, 5×10-3 mm for 2 days arc, compared with GEODYN-Ⅱ;②the difference RMS of computed values of observables for two-way range and two-way range rate is at levels of 0.06 mm and 0.002 mm/s respectively;③for Chinese Chang'E-1 POD, the reconstructed orbit difference between WUDOGS and GEODYN-Ⅱ is at 2 cm level, for ESA MEX POD, the reconstructed orbit difference between WUDOGS and ESA is at 25 m level. Current developing situation of WUDOGS and comparison with international research level show that WUDOGS has a good application prospect, which will be important for meeting the demand of Chinese future planetary exploration and the development of deep space spacecraft POD software.

Traumatic orbital CSF leak

Science.gov (United States)

Borumandi, Farzad

2013-01-01

Compared to the cerebrospinalfluid (CSF) leak through the nose and ear, the orbital CSF leak is a rare and underreported condition following head trauma. We present the case of a 49-year-old woman with oedematous eyelid swelling and ecchymosis after a seemingly trivial fall onto the right orbit. Apart from the above, she was clinically unremarkable. The CT scan revealed a minimally displaced fracture of the orbital roof with no emphysema or intracranial bleeding. The fractured orbital roof in combination with the oedematous eyelid swelling raised the suspicion for orbital CSF leak. The MRI of the neurocranium demonstrated a small-sized CSF fistula extending from the anterior cranial fossa to the right orbit. The patient was treated conservatively and the lid swelling resolved completely after 5 days. Although rare, orbital CSF leak needs to be included in the differential diagnosis of periorbital swelling following orbital trauma. PMID:24323381

A Comprehensive Analysis in Terms of Molecule-Intrinsic, Quasi-Atomic Orbitals. III. The Covalent Bonding Structure of Urea.

Science.gov (United States)

West, Aaron C; Schmidt, Michael W; Gordon, Mark S; Ruedenberg, Klaus

2015-10-15

The analysis of molecular electron density matrices in terms of quasi-atomic orbitals, which was developed in previous investigations, is quantitatively exemplified by a detailed application to the urea molecule. The analysis is found to identify strong and weak covalent bonding interactions as well as intramolecular charge transfers. It yields a qualitative as well as quantitative ab initio description of the bonding structure of this molecule, which raises questions regarding some traditional rationalizations.

Multipole error analysis using local 3-bump orbit data in Fermilab Recycler

International Nuclear Information System (INIS)

Yang, M.J.; Xiao, M.

2005-01-01

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

Determine ISS Soyuz Orbital Module Ballistic Limits for Steel Projectiles Hypervelocity Impact Testing

Science.gov (United States)

Lyons, Frankel

2013-01-01

A new orbital debris environment model (ORDEM 3.0) defines the density distribution of the debris environment in terms of the fraction of debris that are low-density (plastic), medium-density (aluminum) or high-density (steel) particles. This hypervelocity impact (HVI) program focused on assessing ballistic limits (BLs) for steel projectiles impacting the enhanced Soyuz Orbital Module (OM) micrometeoroid and orbital debris (MMOD) shield configuration. The ballistic limit was defined as the projectile size on the threshold of failure of the OM pressure shell as a function of impact speeds and angle. The enhanced OM shield configuration was first introduced with Soyuz 30S (launched in May 2012) to improve the MMOD protection of Soyuz vehicles docked to the International Space Station (ISS). This test program provides HVI data on U.S. materials similar in composition and density to the Russian materials for the enhanced Soyuz OM shield configuration of the vehicle. Data from this test program was used to update ballistic limit equations used in Soyuz OM penetration risk assessments. The objective of this hypervelocity impact test program was to determine the ballistic limit particle size for 440C stainless steel spherical projectiles on the Soyuz OM shielding at several impact conditions (velocity and angle combinations). This test report was prepared by NASA-JSC/ HVIT, upon completion of tests.

A fast optics and orbit correction program

International Nuclear Information System (INIS)

Bowling, B.; Kewisch, J.; Kloeppel, P.; Rossmanith, R.

1990-08-01

CEBAF is a large recirculating linear accelerator with approximately 1600 magnet power supplies in the beam transport system. The average beam power can be as great as 800 kW, concentrated into a spot of area less than 0.01 mm 2 . Control of the transport is therefore quite critical, to avoid missteering the beam. To prevent dangerous beam losses and to prepare optics changes, the control programs must read the magnet power supplies and calculate the optics in a virtually real-time manner. A program named OLE (On-Line Envelope) has been developed at CEBAF to give a graphical display of the calculated machine β function or, equivalently, the beam envelope. The time interval necessary to execute the program is somewhat less than one second, short enough that the operator can use it for setting up his lattice. Emphasis in the design was placed on speed of program execution at the expense of generality of application. As a result, the accelerator operator will be able to alter the magnetic field in any element in the machine, calculate the β functions in both planes at the entrance and exit of each magnet, and display graphs of the functions, all within one second. The time that is required is short enough that the process approximates fairly well real-time operation

Orbitals from local RDMFT: Are they Kohn-Sham or natural orbitals?

International Nuclear Information System (INIS)

Theophilou, Iris; Helbig, Nicole; Lathiotakis, Nektarios N.; Gidopoulos, Nikitas I.; Rubio, Angel

2015-01-01

Recently, an approximate theoretical framework was introduced, called local reduced density matrix functional theory (local-RDMFT), where functionals of the one-body reduced density matrix (1-RDM) are minimized under the additional condition that the optimal orbitals satisfy a single electron Schrödinger equation with a local potential. In the present work, we focus on the character of these optimal orbitals. In particular, we compare orbitals obtained by local-RDMFT with those obtained with the full minimization (without the extra condition) by contrasting them against the exact NOs and orbitals from a density functional calculation using the local density approximation (LDA). We find that the orbitals from local-RMDFT are very close to LDA orbitals, contrary to those of the full minimization that resemble the exact NOs. Since local RDMFT preserves the good quality of the description of strong static correlation, this finding opens the way to a mixed density/density matrix scheme, where Kohn-Sham orbitals obtain fractional occupations from a minimization of the occupation numbers using 1-RDM functionals. This will allow for a description of strong correlation at a cost only minimally higher than a density functional calculation

The orbital record in stratigraphy

Science.gov (United States)

Fischer, Alfred G.

1992-01-01

Orbital signals are being discovered in pre-Pleistocene sediments. Due to their hierarchical nature these cycle patterns are complex, and the imprecision of geochronology generally makes the assignment of stratigraphic cycles to specific orbital cycles uncertain, but in sequences such as the limnic Newark Group under study by Olsen and pelagic Cretaceous sequence worked on by our Italo-American group the relative frequencies yield a definitive match to the Milankovitch hierarchy. Due to the multiple ways in which climate impinges on depositional systems, the orbital signals are recorded in a multiplicity of parameters, and affect different sedimentary facies in different ways. In platform carbonates, for example, the chief effect is via sea-level variations (possibly tied to fluctuating ice volume), resulting in cycles of emergence and submergence. In limnic systems it finds its most dramatic expression in alternations of lake and playa conditions. Biogenic pelagic oozes such as chalks and the limestones derived from them display variations in the carbonate supplied by planktonic organisms such as coccolithophores and foraminifera, and also record variations in the aeration of bottom waters. Whereas early studies of stratigraphic cyclicity relied mainly on bedding variations visible in the field, present studies are supplementing these with instrumental scans of geochemical, paleontological, and geophysical parameters which yield quantitative curves amenable to time-series analysis; such analysis is, however, limited by problems of distorted time-scales. My own work has been largely concentrated on pelagic systems. In these, the sensitivity of pelagic organisms to climatic-oceanic changes, combined with the sensitivity of botton life to changes in oxygen availability (commonly much more restricted in the Past than now) has left cyclic patterns related to orbital forcing. These systems are further attractive because (1) they tend to offer depositional continuity

Space Shuttle Orbiter logistics - Managing in a dynamic environment

Science.gov (United States)

Renfroe, Michael B.; Bradshaw, Kimberly

1990-01-01

The importance and methods of monitoring logistics vital signs, logistics data sources and acquisition, and converting data into useful management information are presented. With the launch and landing site for the Shuttle Orbiter project at the Kennedy Space Center now totally responsible for its own supportability posture, it is imperative that logistics resource requirements and management be continually monitored and reassessed. Detailed graphs and data concerning various aspects of logistics activities including objectives, inventory operating levels, customer environment, and data sources are provided. Finally, some lessons learned from the Shuttle Orbiter project and logistics options which should be considered by other space programs are discussed.

Energy Analysis Program 1990 annual report

Energy Technology Data Exchange (ETDEWEB)

1992-01-01

The Energy Analysis Program has played an active role in the analysis and discussion of energy and environmental issues at several levels. (1) at the international level, with programs as developing scenarios for long-term energy demand in developing countries and organizing leading an analytic effort, Energy Efficiency, Developing Countries, and Eastern Europe,'' part of a major effort to increase support for energy efficiency programs worldwide; (2) at national level, the Program has been responsible for assessing energy forecasts and policies affecting energy use (e.g., appliance standards, National Energy Strategy scenarios); and (3) at the state and utility levels, the Program has been a leader in promoting integrated resource utility planning; the collaborative process has led to agreement on a new generation of utility demand-site programs in California, providing an opportunity to use knowledge and analytic techniques of the Program's researchers. We continue to place highest on analyzing energy efficiency, with particular attention given to energy use in buildings. The Program continues its active analysis of international energy issues in Asia (including China), the Soviet Union, South America, and Western Europe. Analyzing the costs and benefits of different levels of standards for residential appliances continues to be the largest single area of research within the Program. The group has developed and applied techniques for forecasting energy demand (or constructing scenarios) for the United States. We have built a new model of industrial energy demand, are in the process of making major changes in our tools for forecasting residential energy demand, have built an extensive and documented energy conservation supply curve of residential energy use, and are beginning an analysis of energy-demand forecasting for commercial buildings.

Masses, radii, and orbits of small Kepler planets

DEFF Research Database (Denmark)

Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.

2014-01-01

We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurement...

Lunar orbiter photographic atlas of the near side of the Moon

CERN Document Server

Byrne, Charles

2005-01-01

In 1967, Lunar Orbiter Mission 4 sent back to Earth a superb series of photographs of the surface of the Moon. Using 21st century computer techniques, Charles Byrne - previously System Engineer of the Apollo Program for Lunar Orbiter Photography - has removed the scanning artifacts and transmission imperfections to produce a most comprehensive and beautifully detailed set of images of the lunar surface. To help practical astronomers, all the photographs are systematically related to an Earth-based view. The book has been organized to make it easy for astronomers to use, enabling ground-based images and views to be compared with the Orbiter photographs. Every astronomer - amateur and professional - who is interested in the Moon will want this book in his library!.

The Y2K program for scientific-analysis computer programs at AECL

International Nuclear Information System (INIS)

Popovic, J.; Gaver, C.; Chapman, D.

1999-01-01

The evaluation of scientific-analysis computer programs for year-2000 compliance is part of AECL' s year-2000 (Y2K) initiative, which addresses both the infrastructure systems at AECL and AECL's products and services. This paper describes the Y2K-compliance program for scientific-analysis computer codes. This program involves the integrated evaluation of the computer hardware, middleware, and third-party software in addition to the scientific codes developed in-house. The project involves several steps: the assessment of the scientific computer programs for Y2K compliance, performing any required corrective actions, porting the programs to Y2K-compliant platforms, and verification of the programs after porting. Some programs or program versions, deemed no longer required in the year 2000 and beyond, will be retired and archived. (author)

The Y2K program for scientific-analysis computer programs at AECL

International Nuclear Information System (INIS)

Popovic, J.; Gaver, C.; Chapman, D.

1999-01-01

The evaluation of scientific analysis computer programs for year-2000 compliance is part of AECL's year-2000 (Y2K) initiative, which addresses both the infrastructure systems at AECL and AECL's products and services. This paper describes the Y2K-compliance program for scientific-analysis computer codes. This program involves the integrated evaluation of the computer hardware, middleware, and third-party software in addition to the scientific codes developed in-house. The project involves several steps: the assessment of the scientific computer programs for Y2K compliance, performing any required corrective actions, porting the programs to Y2K-compliant platforms, and verification of the programs after porting. Some programs or program versions, deemed no longer required in the year 2000 and beyond, will be retired and archived. (author)

Orbital transfer vehicle concept definition and system analysis study. Volume 2: OTV concept definition and evaluation. Book 1: Mission and system requirements

Science.gov (United States)

Kofal, Allen E.

1987-01-01

The mission and system requirements for the concept definition and system analysis of the Orbital Transfer Vehicle (OTV) are established. The requirements set forth constitute the single authority for the selection, evaluation, and optimization of the technical performance and design of the OTV. This requirements document forms the basis for the Ground and Space Based OTV concept definition analyses and establishes the physical, functional, performance and design relationships to STS, Space Station, Orbital Maneuvering Vehicle (OMV), and payloads.

Calibration of SeaWiFS after two years on orbit

Science.gov (United States)

Barnes, Robert A.; McClain, Charles R.

1999-12-01

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) was launched on 1 August 1997, and the first Earth images were taken on 4 September 1997. Regular, daily measurements of the sun, via the onboard diffuser, started on 9 September 1997 and regular, monthly measurements of the moon on November 14, 1997. These lunar measurements, as first reported at EUROPTO'98, provide a highly sensitive method for determining the change in the radiometric sensitivity of SeaWiFS. The prelaunch radiometric calibration used by SeaWiFS was performed in the Spring of 1997 at the spacecraft manufacturer's facility. The calibration measurements were made by a team from the National Institute of Standards and Technology (NIST) and the SeaWiFS Project. The uncertainties in this calibration range from 2% to 3% for the eight SeaWiFS bands. In addition, a set of outdoor measurements of the sun were made at the instrument manufacturer's facility in November 1993, just before the delivery of SeaWiFS to the spacecraft manufacturer. These solar measurements, using the instrument's diffuser, were combined with a separate set of solar radiometer measurements to determine the transmittance of the atmosphere. At the start of on-orbit measurements by SeaWiFS, solar measurements were made again by the instrument. These two sets of measurements make up the transfer-to-orbit experiment. From the ground measurements, the outputs of the SeaWiFS bands on orbit were predicted. For each band, the output from the initial on-orbit measurements agree with the predicted values by 21/2% or less. The uncertainties for the transfer-to-orbit experiment are estimated to be approximately 3% to 4%. From 14 November 1997 to 29 June 1999, SeaWiFS has made 20 measurements of the moon. The analysis of lunar measurements presented here has minor modifications to that presented at EUROPTO'98. The trend lines from the current analysis have been extrapolated back from 14 November 1997 to 4 September 1997 to describe the changes

The search For Closed Orbits Of General Rydberg Atoms in External Fields And Their Classification

International Nuclear Information System (INIS)

Carboni, R.

1997-01-01

A program of high precision that find closed orbits for the classical motion of the electron of general Rydberg atoms in crossed magnetic and electric fields is explained. Investigations of the influence of the ionic core on the electronic trajectories using a phenomenological model potential were done. Additional closed orbits that are not present in hydrogen atoms and that seem to be composed of hydrogenic orbits were found. The stability and formation of orbits are explained. Using the generalized closed-orbit theory, the scaled recurrence spectra for rubidium Rydberg atoms were calculated. The results are in good agreement with reported experiments. Two important features of the expectra can be explained by classical core scattering: The additional non-hydrogenic resonances associated to composite orbits and the vanishing of hydrogenic resonances related to closed or whose trajectories approach the core. (Author) [es

The spin-orbit interaction in nuclei

International Nuclear Information System (INIS)

Skyrme, T.H.R.

1994-01-01

The analysis previously made of the average nuclear potential has been extended to consideration of the spin-orbit interactions. It has not been possible to find a satisfactory two-body interaction consistent with all the data; that suggested by the phase-shift analysis of nucleon-nucleon scattering is just within the region of possible forms. (author). 13 refs, 1 fig

Resonant Orbital Dynamics in LEO Region: Space Debris in Focus

Directory of Open Access Journals (Sweden)

J. C. Sampaio

2014-01-01

Full Text Available The increasing number of objects orbiting the earth justifies the great attention and interest in the observation, spacecraft protection, and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. In this work, objects in resonant orbital motions are studied in low earth orbits. Using the two-line elements (TLE of the NORAD, resonant angles and resonant periods associated with real motions are described, providing more accurate information to develop an analytical model that describes a certain resonance. The time behaviors of the semimajor axis, eccentricity, and inclination of some space debris are studied. Possible irregular motions are observed by the frequency analysis and by the presence of different resonant angles describing the orbital dynamics of these objects.

Programs for nuclear data analysis

International Nuclear Information System (INIS)

Bell, R.A.I.

1975-01-01

The following report details a number of programs and subroutines which are useful for analysis of data from nuclear physics experiments. Most of them are available from pool pack 005 on the IBM1800 computer. All of these programs are stored there as core loads, and the subroutines and functions in relocatable format. The nature and location of other programs are specified as appropriate. (author)

Dynamic analysis program for frame structure

International Nuclear Information System (INIS)

Ando, Kozo; Chiba, Toshio

1975-01-01

A general purpose computer program named ISTRAN/FD (Isub(HI) STRucture ANalysis/Frame structure, Dynamic analysis) has been developed for dynamic analysis of three-dimensional frame structures. This program has functions of free vibration analysis, seismic response analysis, graphic display by plotter and CRT, etc. This paper introduces ISTRAN/FD; examples of its application are shown with various problems : idealization of the cantilever, dynamic analysis of the main tower of the suspension bridge, three-dimensional vibration in the plate girder bridge, seismic response in the boiler steel structure, and dynamic properties of the underground LNG tank. In this last example, solid elements, in addition to beam elements, are especially used for the analysis. (auth.)

Abort Options for Human Missions to Earth-Moon Halo Orbits

Science.gov (United States)

Jesick, Mark C.

2013-01-01

Abort trajectories are optimized for human halo orbit missions about the translunar libration point (L2), with an emphasis on the use of free return trajectories. Optimal transfers from outbound free returns to L2 halo orbits are numerically optimized in the four-body ephemeris model. Circumlunar free returns are used for direct transfers, and cislunar free returns are used in combination with lunar gravity assists to reduce propulsive requirements. Trends in orbit insertion cost and flight time are documented across the southern L2 halo family as a function of halo orbit position and free return flight time. It is determined that the maximum amplitude southern halo incurs the lowest orbit insertion cost for direct transfers but the maximum cost for lunar gravity assist transfers. The minimum amplitude halo is the most expensive destination for direct transfers but the least expensive for lunar gravity assist transfers. The on-orbit abort costs for three halos are computed as a function of abort time and return time. Finally, an architecture analysis is performed to determine launch and on-orbit vehicle requirements for halo orbit missions.

Antisymmetric Orbit Functions

Directory of Open Access Journals (Sweden)

Anatoliy Klimyk

2007-02-01

Full Text Available In the paper, properties of antisymmetric orbit functions are reviewed and further developed. Antisymmetric orbit functions on the Euclidean space $E_n$ are antisymmetrized exponential functions. Antisymmetrization is fulfilled by a Weyl group, corresponding to a Coxeter-Dynkin diagram. Properties of such functions are described. These functions are closely related to irreducible characters of a compact semisimple Lie group $G$ of rank $n$. Up to a sign, values of antisymmetric orbit functions are repeated on copies of the fundamental domain $F$ of the affine Weyl group (determined by the initial Weyl group in the entire Euclidean space $E_n$. Antisymmetric orbit functions are solutions of the corresponding Laplace equation in $E_n$, vanishing on the boundary of the fundamental domain $F$. Antisymmetric orbit functions determine a so-called antisymmetrized Fourier transform which is closely related to expansions of central functions in characters of irreducible representations of the group $G$. They also determine a transform on a finite set of points of $F$ (the discrete antisymmetric orbit function transform. Symmetric and antisymmetric multivariate exponential, sine and cosine discrete transforms are given.

Angles-only relative orbit determination in low earth orbit

Science.gov (United States)

Ardaens, Jean-Sébastien; Gaias, Gabriella

2018-06-01

The paper provides an overview of the angles-only relative orbit determination activities conducted to support the Autonomous Vision Approach Navigation and Target Identification (AVANTI) experiment. This in-orbit endeavor was carried out by the German Space Operations Center (DLR/GSOC) in autumn 2016 to demonstrate the capability to perform spaceborne autonomous close-proximity operations using solely line-of-sight measurements. The images collected onboard have been reprocessed by an independent on-ground facility for precise relative orbit determination, which served as ultimate instance to monitor the formation safety and to characterize the onboard navigation and control performances. During two months, several rendezvous have been executed, generating a valuable collection of images taken at distances ranging from 50 km to only 50 m. Despite challenging experimental conditions characterized by a poor visibility and strong orbit perturbations, angles-only relative positioning products could be continuously derived throughout the whole experiment timeline, promising accuracy at the meter level during the close approaches. The results presented in the paper are complemented with former angles-only experience gained with the PRISMA satellites to better highlight the specificities induced by different orbits and satellite designs.

A program for activation analysis data processing

International Nuclear Information System (INIS)

Janczyszyn, J.; Loska, L.; Taczanowski, S.

1978-01-01

An ALGOL program for activation analysis data handling is presented. The program may be used either for single channel spectrometry data or for multichannel spectrometry. The calculation of instrumental error and of analysis standard deviation is carried out. The outliers are tested, and the regression line diagram with the related observations are plotted by the program. (author)

Orbital fractures: a review

Directory of Open Access Journals (Sweden)

Jeffrey M Joseph

2011-01-01

Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures 

Posttraumatic subperiosteal hematomas of the orbit in children.

Science.gov (United States)

Yazici, Bülent; Gönen, Tansu

2011-01-01

To describe 5 pediatric patients with traumatic orbital subperiosteal hematoma and review the relevant literature. Retrospective chart analysis of 5 children with posttraumatic subperiosteal hematoma and a systematic review of the English language literature. Five new pediatric cases of orbital subperiosteal hematoma are presented with varying clinical and radiologic manifestations and treatments. Literature review (including the current 5 cases) yielded 23 cases in total. Eighteen (78%) of the patients were boys, and 5 (22%) were girls. The children ranged in age from 5 to 17 years, with the mean and median ages being 12 years. The leading cause was blunt trauma related to falls or direct impact. Two patients (9%) had an inherited coagulopathy, predisposing them to orbital hemorrhage. The hematomas developed in the superior orbit in all cases except one. In 3 patients (13%), orbital hematomas were bilateral. In 9 patients (39%), the hematomas extended in subgaleal or frontal subdural spaces. In 7 patients (30%), subperiosteal hematoma was associated with compressive optic neuropathy. Four patients (17%) had a nondisplaced orbital roof fracture. Seventeen patients were treated with surgical evacuation of hematoma (52%) or with needle aspiration (22%), and 5 patients (22%) were observed for spontaneous resolution. Three patients (13%) experienced a recurrence of hemorrhage. In children, traumatic subperiosteal hematomas of the orbit typically occur after blunt trauma in the superior orbit. The risk of compressive optic neuropathy may be higher in patients with bilateral hematoma and massive subgaleal hematoma. Most patients are treated with evacuation of the hematoma.

Precise Orbit Determination of GPS Satellites Using Phase Observables

Directory of Open Access Journals (Sweden)

Myung-Kook Jee

1997-12-01

Full Text Available The accuracy of user position by GPS is heavily dependent upon the accuracy of satellite position which is usually transmitted to GPS users in radio signals. The real-time satellite position information directly obtained from broadcast ephimerides has the accuracy of 3 x 10 meters which is very unsatisfactory to measure 100km baseline to the accuracy of less than a few mili-meters. There are globally at present seven orbit analysis centers capable of generating precise GPS ephimerides and their orbit quality is of the order of about 10cm. Therefore, precise orbit model and phase processing technique were reviewed and consequently precise GPS ephimerides were produced after processing the phase observables of 28 global GPS stations for 1 day. Initial 6 orbit parameters and 2 solar radiation coefficients were estimated using batch least square algorithm and the final results were compared with the orbit of IGS, the International GPS Service for Geodynamics.

Orbit stability and feedback control in synchrotron radiation rings

International Nuclear Information System (INIS)

Yu, L.H.

1989-01-01

Stability of the electron orbit is essential for the utilization of a low emittance storage ring as a high brightness radiation source. We discuss the development of the measurement and feedback control of the closed orbit, with emphasis on the activities as the National Synchrotron Light Source of BNL. We discuss the performance of the beam position detectors in use and under development: the PUE rf detector, split ion chamber detector, photo-emission detector, solid state detector, and the graphite detector. Depending on the specific experiments, different beamlines require different tolerances on the orbit motion. Corresponding to these different requirements, we discuss two approaches to closed orbit feedback: the global and local feedback systems. Then we describe a new scheme for the real time global feedback by implementing a feedback system based upon a harmonic analysis of both the orbit movements and the correction magnetic fields. 14 refs., 6 figs., 2 tabs

NASA logo painted on orbiter Endeavour

Science.gov (United States)

1998-01-01

A KSC worker paints the NASA logo on the port wing of the orbiter Endeavour, which is scheduled to launch in December for STS-88. The paint is a special pigment that takes 18 hours to dry; the whole process takes approximately two weeks to complete. The NASA logo, termed 'meatball,' was originally designed in the late 1950s. It symbolized NASA's role in aeronautics and space in the early years of the agency. The original design included a white border surrounding it. The border was dropped for the Apollo 7 mission in October 1968, replaced with royal blue to match the background of the emblem. In 1972 the logo was replaced by a simple and contemporary design -- the 'worm' -- which was retired from use last year. NASA reverted to its original logo in celebration of the agency's 40th anniversary in October, and the 'golden age' of America's space program. All the orbiters will bear the new logo.

Peripheral orbit model

CERN Document Server

Hara, Yasuo

1975-01-01

Peripheral orbit model, in which an incoming hadron is assumed to revolve in a peripheral orbit around a target hadron, is discussed. The non-diffractive parts of two-body reaction amplitudes of hadrons are expressed in terms of the radius, width an absorptivity of the orbit. The radius of the orbit is about 1 fm and the width of the orbit is determined by the range of the interaction between the hadrons. The model reproduces all available experimental data on differential cross-sections and polarizations of $K^{-}p\\to K^{-}p$ and $\\bar K^{\\circ}n$ reactions for all angles successfully. This contribution is not included in the proceedings since it will appear in Progress of Theoretical Physics Vol. 51 (1974) No 2. Any person interested in the subject may apply for reprints to the author.

An algorithm for enhanced formation flying of satellites in low earth orbit

Science.gov (United States)

Folta, David C.; Quinn, David A.

1998-01-01

With scientific objectives for Earth observation programs becoming more ambitious and spacecraft becoming more autonomous, the need for innovative technical approaches on the feasibility of achieving and maintaining formations of spacecraft has come to the forefront. The trend to develop small low-cost spacecraft has led many scientists to recognize the advantage of flying several spacecraft in formation to achieve the correlated instrument measurements formerly possible only by flying many instruments on a single large platform. Yet, formation flying imposes additional complications on orbit maintenance, especially when each spacecraft has its own orbit requirements. However, advances in automation and technology proposed by the Goddard Space Flight Center (GSFC) allow more of the burden in maneuver planning and execution to be placed onboard the spacecraft, mitigating some of the associated operational concerns. The purpose of this paper is to present GSFC's Guidance, Navigation, and Control Center's (GNCC) algorithm for Formation Flying of the low earth orbiting spacecraft that is part of the New Millennium Program (NMP). This system will be implemented as a close-loop flight code onboard the NMP Earth Orbiter-1 (EO-1) spacecraft. Results of this development can be used to determine the appropriateness of formation flying for a particular case as well as operational impacts. Simulation results using this algorithm integrated in an autonomous `fuzzy logic' control system called AutoCon™ are presented.

Orbital transport

International Nuclear Information System (INIS)

Oertel, H. Jr.; Koerner, H.

1993-01-01

The Third Aerospace Symposium in Braunschweig presented, for the first time, the possibility of bringing together the classical disciplines of aerospace engineering and the natural science disciplines of meteorology and air chemistry in a european setting. In this way, aspects of environmental impact on the atmosphere could be examined quantitatively. An essential finding of the european conference, is the unrestricted agreement of the experts that the given launch frequencies of the present orbital transport result in a negligible amount of pollutants being released in the atmosphere. The symposium does, however, call attention to the increasing need to consider the effect of orbital and atmospheric environmental impact of a future increase in launch frequencies of orbital transport in connection with future space stations. The Third Aerospace Symposium, 'Orbital Transport, Technical, Meteorological and Chemical Aspects', constituted a first forum of discussion for engineers and scientists. Questions of new orbital transport technologies and their environmental impact were to be discussed towards a first consensus. Through the 34 reports and articles, the general problems of space transportation and environmental protection were addressed, as well as particular aspects of high temperatures during reentry in the atmosphere of the earth, precision navigation of flight vehicles or flow behavior and air chemistry in the stratosphere. (orig./CT). 342 figs

Orbital apex syndrome associated with fractures of the inferomedial orbital wall

Directory of Open Access Journals (Sweden)

Sugamata A

2013-03-01

Full Text Available Akira SugamataDepartment of Plastic and Reconstructive Surgery, Tokyo Medical University Hachioji Medical Center, Tokyo, JapanAbstract: Although trauma is one of the main causes of orbital apex syndrome (OAS, reports of OAS associated with orbital fractures are relatively rare. We recently treated two patients who sustained severe visual impairment with damage to multiple cranial nerves (third to sixth associated with inferomedial orbital wall fractures. In these patients, posterior movement of the globe caused neuropathy of the cranial and optic nerves by posterior globe edema and hemorrhage, or direct impact between the globe and wall, which might then have induced OAS in the cases described in this report. Steroid therapy was unsuccessful for optic neuropathy due to the delay between injury and administration. When treating patients with inferomedial orbital blowout fractures due to globe-to-wall contact, it is necessary to routinely assess and monitor visual acuity since there may be a delay between the injury and OAS onset.Keywords: orbital apex syndrome, orbital fracture, blowout fracture, optic nerve, globe-to-wall contact mechanism

The relationship of the globe to the orbital rim.

Science.gov (United States)

Eckstein, Lauren A; Shadpour, Joseph M; Menghani, Ravi; Goldberg, Robert A

2011-01-01

racial differences in the surface anatomy of the periorbital area. Anatomic analysis, based on 3-dimensional orbital imaging, may provide a rational approach to surgical planning for aesthetic and reconstructive orbitofacial surgery.

Double perovskites with strong spin-orbit coupling

Science.gov (United States)

Cook, Ashley M.

We first present theoretical analysis of powder inelastic neutron scattering experiments in Ba2FeReO6 performed by our experimental collaborators. Ba2FeReO6, a member of the double perovskite family of materials, exhibits half-metallic behavior and high Curie temperatures Tc, making it of interest for spintronics applications. To interpret the experimental data, we develop a local moment model, which incorporates the interaction of Fe spins with spin-orbital locked magnetic moments on Re, and show that it captures the experimental observations. We then develop a tight-binding model of the double perovskite Ba 2FeReO6, a room temperature ferrimagnet with correlated and spin-orbit coupled Re t2g electrons moving in the background of Fe moments stabilized by Hund's coupling. We show that for such 3d/5d double perovskites, strong correlations on the 5d-element (Re) are essential in driving a half-metallic ground state. Incorporating both strong spin-orbit coupling and the Hubbard repulsion on Re leads to a band structure consistent with ab initio calculations. The uncovered interplay of strong correlations and spin-orbit coupling lends partial support to our previous work, which used a local moment description to capture the spin wave dispersion found in neutron scattering measurements. We then adapt this tight-binding model to study {111}-grown bilayers of half-metallic double perovskites such as Sr2FeMoO6. The combination of spin-orbit coupling, inter-orbital hybridization and symmetry-allowed trigonal distortion leads to a rich phase diagram with tunable ferromagnetic order, topological C= +/-1, +/-2 Chern bands, and a C = +/-2 quantum anomalous Hall insulator regime. We have also performed theoretical analysis of inelastic neutron scattering (INS) experiments to investigate the magnetic excitations in the weakly distorted face-centered-cubic (fcc) iridate double perovskites La2ZnIrO 6 and La2MgIrO6. Models with dominant Kitaev exchange seem to most naturally

Prospective Ukrainian lunar orbiter mission

Science.gov (United States)

Shkuratov, Y.; Litvinenko, L.; Shulga, V.; Yatskiv, Y.; Kislyuk, V.

Ukraine has launch vehicles that are able to deliver about 300 kg to the lunar orbit. Future Ukrainian lunar program may propose a polar orbiter. This orbiter should fill principal information gaps in our knowledge about the Moon after Clementine and Lunar Prospector missions and the future missions, like Smart-1, Lunar-A, and Selene. We consider that this can be provided by radar studies of the Moon with supporting optical polarimetric observations from lunar polar orbit. These experiments allow one to better understand global structure of the lunar surface in a wide range of scales, from microns to kilometers. We propose three instruments for the prospective lunar orbiter. They are: a synthetic aperture imaging radar (SAR), ground-penetrating radar (GPR), and imaging polarimeter (IP). The main purpose of SAR is to study with high resolution (50 m) the permanently shadowed sites in the lunar polar regions. These sites are cold traps for volatiles, and have a potential of resource utilization. Possible presence of water ice in the regolith in the sites makes them interesting for permanent manned bases on the Moon. Radar imaging and mapping of other interesting regions could be also planned. Multi-frequencies multi-polarization soun d ing of the lunar surface with GPR can provide information about internal structure of the lunar surface from meters to several hundred meters deep. GPR can be used for measuring the megaregolith layer properties, detection of cryptomaria, and studies of internal structure of the largest craters. IP will be a CCD camera with an additional suite of polarizers. Modest spatial resolution (100 m) should provide a total coverage or a large portion of the lunar surface in oblique viewing basically at large phase angles. Polarization degree at large (>90°) phase angles bears information about characteristic size of the regolith particles. Additional radiophysical experiments are considered with the use of the SAR system, e.g., bistatic radar

Static Analysis of Functional Programs

NARCIS (Netherlands)

van den Berg, Klaas; van den Broek, P.M.

1994-01-01

In this paper, the static analysis of programs in the functional programming language Miranda is described based on two graph models. A new control-flow graph model of Miranda definitions is presented, and a model with four classes of caligraphs. Standard software metrics are applicable to these

On the atmospheric drag in orbit determination for low Earth orbit

Science.gov (United States)

Tang, Jingshi; Liu, Lin; Miao, Manqian

2012-07-01

The atmosphere model is always a major limitation for low Earth orbit (LEO) in orbit prediction and determination. The accelerometer can work around the non-gravitational perturbations in orbit determination, but it helps little to improve the atmosphere model or to predict the orbit. For certain satellites, there may be some specific software to handle the orbit problem. This solution can improve the orbit accuracy for both prediction and determination, yet it always contains empirical terms and is exclusive for certain satellites. This report introduces a simple way to handle the atmosphere drag for LEO, which does not depend on instantaneous atmosphere conditions and improves accuracy of predicted orbit. This approach, which is based on mean atmospheric density, is supported by two reasons. One is that although instantaneous atmospheric density is very complicated with time and height, the major pattern is determined by the exponential variation caused by hydrostatic equilibrium and periodic variation caused by solar radiation. The mean density can include the major variations while neglect other minor details. The other reason is that the predicted orbit is mathematically the result from integral and the really determinant factor is the mean density instead of instantaneous density for every time and spot. Using the mean atmospheric density, which is mainly determined by F10.7 solar flux and geomagnetic index, can be combined into an overall parameter B^{*} = C_{D}(S/m)ρ_{p_{0}}. The combined parameter contains several less accurate parameters and can be corrected during orbit determination. This approach has been confirmed in various LEO computations and an example is given below using Tiangong-1 spacecraft. Precise orbit determination (POD) is done using one-day GPS positioning data without any accurate a-priori knowledge on spacecraft or atmosphere conditions. Using the corrected initial state vector of the spacecraft and the parameter B^* from POD, the

Space station orbit maintenance

Science.gov (United States)

Kaplan, D. I.; Jones, R. M.

1983-01-01

The orbit maintenance problem is examined for two low-earth-orbiting space station concepts - the large, manned Space Operations Center (SOC) and the smaller, unmanned Science and Applications Space Platform (SASP). Atmospheric drag forces are calculated, and circular orbit altitudes are selected to assure a 90 day decay period in the event of catastrophic propulsion system failure. Several thrusting strategies for orbit maintenance are discussed. Various chemical and electric propulsion systems for orbit maintenance are compared on the basis of propellant resupply requirements, power requirements, Shuttle launch costs, and technology readiness.

Earth Orbiting Support Systems for commercial low Earth orbit data relay: Assessing architectures through tradespace exploration

Science.gov (United States)

Palermo, Gianluca; Golkar, Alessandro; Gaudenzi, Paolo

2015-06-01

As small satellites and Sun Synchronous Earth Observation systems are assuming an increased role in nowadays space activities, including commercial investments, it is of interest to assess how infrastructures could be developed to support the development of such systems and other spacecraft that could benefit from having a data relay service in Low Earth Orbit (LEO), as opposed to traditional Geostationary relays. This paper presents a tradespace exploration study of the architecture of such LEO commercial satellite data relay systems, here defined as Earth Orbiting Support Systems (EOSS). The paper proposes a methodology to formulate architectural decisions for EOSS constellations, and enumerate the corresponding tradespace of feasible architectures. Evaluation metrics are proposed to measure benefits and costs of architectures; lastly, a multicriteria Pareto criterion is used to downselect optimal architectures for subsequent analysis. The methodology is applied to two case studies for a set of 30 and 100 customer-spacecraft respectively, representing potential markets for LEO services in Exploration, Earth Observation, Science, and CubeSats. Pareto analysis shows how increased performance of the constellation is always achieved by an increased node size, as measured by the gain of the communications antenna mounted on EOSS spacecraft. On the other hand, nonlinear trends in optimal orbital altitude, number of satellites per plane, and number of orbital planes, are found in both cases. An upward trend in individual node memory capacity is found, although never exceeding 256 Gbits of onboard memory for both cases that have been considered, assuming the availability of a polar ground station for EOSS data downlink. System architects can use the proposed methodology to identify optimal EOSS constellations for a given service pricing strategy and customer target, thus identifying alternatives for selection by decision makers.

Some schemes for on-line correction of the closed orbit, dispersion and beta functions in PEP

International Nuclear Information System (INIS)

Donald, M.H.R.; Blocker, C.; Chao, A.W.; Hollebeek, R.J.; Lee, M.J.; Linstadt, J.E.; Siegrist, J.L.; Spencer, N.

1981-02-01

PEP has been operated successfully under computer control. It is necessary for colliding beam operation that the errors in closed orbits, dispersion and beta functions be corrected. The schemes in the PEP control program for on-line correction of these errors are described in this paper. The orbit control tasks in the PEP control system perform the functions of data gathering, data presentation (color display, printing), calculation and setting of corrector magnets. The tasks are generally small and modular, taking information from the database, processing it, then returning the results to the database. The PEP operator communicates with the tasks through touch panels monitored by the Director program. The display task, which displays orbit and corrector information on a TV color display, provides the main information required by the operator

A natural orbital analysis of the helium (e,2e) spectrum

International Nuclear Information System (INIS)

Mitroy, J.; McCarthy, I.E.; Weigold, E.

1984-10-01

A series of successively more accurate wavefunctions (of the Natural Orbital form) for the helium atom ground state is used to analyse the 1200eV non-coplanar symmetric (e,2e) data for helium with the Plane Wave Impulse Approximation. Particular attention is focussed upon the determination of the ratio for populating the n = 2 (2s and 2p) and 1s ion states. It is seen that the cross-section ratio (at low recoil momentum) converges satisfactorily as additional target natural orbitals are utilised for the calculation of the overlap function. The convergence of the cross-section ratio at high azimuthal angles is seen to be much slower

Cassini-Huygens Nears Saturn Orbit Insertion

Science.gov (United States)

Showstack, Randy

2004-06-01

After nearly 7 years and a 3.5-billion-km, circuitous journey from Earth, the $3-billion Cassini-Huygens mission to Saturn and Titan-an international effort by NASA, the European Space Agency, and the Italian Space Agency-now is just days away from its critical Saturn orbit insertion. Scheduled for 30 June, this will begin the 4-years part of the mission to study the Saturnian system. At a 3 June briefing at NASA headquarters in Washington, D.C., Robert Mitchell, the Cassini program manager with the Jet Propulsion Laboratory in Pasadena, California, said that scientists involved with the program are feeling excited, relieved, and also a bit anxious as the Cassini-Huygens spacecraft draws near to the ringed planet and its system.

Orbit error characteristic and distribution of TLE using CHAMP orbit data

Science.gov (United States)

Xu, Xiao-li; Xiong, Yong-qing

2018-02-01

Space object orbital covariance data is required for collision risk assessments, but publicly accessible two line element (TLE) data does not provide orbital error information. This paper compared historical TLE data and GPS precision ephemerides of CHAMP to assess TLE orbit accuracy from 2002 to 2008, inclusive. TLE error spatial variations with longitude and latitude were calculated to analyze error characteristics and distribution. The results indicate that TLE orbit data are systematically biased from the limited SGP4 model. The biases can reach the level of kilometers, and the sign and magnitude are correlate significantly with longitude.

An Orbit Propagation Software for Mars Orbiting Spacecraft

Directory of Open Access Journals (Sweden)

Young-Joo Song

2004-12-01

Full Text Available An orbit propagation software for the Mars orbiting spacecraft has been developed and verified in preparations for the future Korean Mars missions. Dynamic model for Mars orbiting spacecraft has been studied, and Mars centered coordinate systems are utilized to express spacecraft state vectors. Coordinate corrections to the Mars centered coordinate system have been made to adjust the effects caused by Mars precession and nutation. After spacecraft enters Sphere of Influence (SOI of the Mars, the spacecraft experiences various perturbation effects as it approaches to Mars. Every possible perturbation effect is considered during integrations of spacecraft state vectors. The Mars50c gravity field model and the Mars-GRAM 2001 model are used to compute perturbation effects due to Mars gravity field and Mars atmospheric drag, respectively. To compute exact locations of other planets, JPL's DE405 ephemerides are used. Phobos and Deimos's ephemeris are computed using analytical method because their informations are not released with DE405. Mars Global Surveyor's mapping orbital data are used to verify the developed propagator performances. After one Martian day propagation (12 orbital periods, the results show about maximum ±5 meter errors, in every position state components(radial, cross-track and along-track, when compared to these from the Astrogator propagation in the Satellite Tool Kit. This result shows high reliability of the developed software which can be used to design near Mars missions for Korea, in future.

Cryogenic implications of orbit selection of the Space Infrared Telescope Facility (SIRTF)

International Nuclear Information System (INIS)

Lee, J.H.; Brooke, W.F.; Maa, S.

1986-01-01

The Infrared Astronomical Satellite (IRAS) which completed the first all sky survey in the infrared demonstrated the tremendous advantage of space-based infrared astronomy. The ability to cool the telescope optics and focal plane to liquid helium temperatures and the absence of atmospheric disturbances which cause ''seeing'' effects resulted in the discovery of 250,000 IR sources and many interesting phenomena including dust clouds around Vega and the infrared ''cirrus'' at 100 μm. To realize the true benefit of space infrared astronomy, NASA is now studying the Space Infrared Telescope Facility, a long-life space-based observatory, to follow up on the survey results of IRAS. The choice of orbits is a critical program decision. The objective of this paper is to compare the performance of an all superfluid helium SIRTF system in the two possible orbit inclinations, polar orbit (99 0 ) and the low inclination orbit (28.5 0 )

Analysis of Logic Programs Using Regular Tree Languages

DEFF Research Database (Denmark)

Gallagher, John Patrick

2012-01-01

The eld of nite tree automata provides fundamental notations and tools for reasoning about set of terms called regular or recognizable tree languages. We consider two kinds of analysis using regular tree languages, applied to logic programs. The rst approach is to try to discover automatically...... a tree automaton from a logic program, approximating its minimal Herbrand model. In this case the input for the analysis is a program, and the output is a tree automaton. The second approach is to expose or check properties of the program that can be expressed by a given tree automaton. The input...... to the analysis is a program and a tree automaton, and the output is an abstract model of the program. These two contrasting abstract interpretations can be used in a wide range of analysis and verication problems....

Multi-GNSS orbit determination using satellite laser ranging

Science.gov (United States)

Bury, Grzegorz; Sośnica, Krzysztof; Zajdel, Radosław

2018-04-01

Galileo, BeiDou, QZSS, and NavIC are emerging global navigation satellite systems (GNSSs) and regional navigation satellite systems all of which are equipped with laser retroreflector arrays for range measurements. This paper summarizes the GNSS-intensive tracking campaigns conducted by the International Laser Ranging Service and provides results from multi-GNSS orbit determination using solely SLR observations. We consider the whole constellation of GLONASS, all active Galileo, four BeiDou satellites: 1 MEO, 3 IGSO, and one QZSS. We analyze the influence of the number of SLR observations on the quality of the 3-day multi-GNSS orbit solution. About 60 SLR observations are needed for obtaining MEO orbits of sufficient quality with the root mean square (RMS) of 3 cm for the radial component when compared to microwave-based orbits. From the analysis of a minimum number of tracking stations, when considering the 3-day arcs, 5 SLR stations do not provide a sufficient geometry of observations. The solution obtained using ten stations is characterized with RMS of 4, 9, and 18 cm in the radial, along-track, and cross-track direction, respectively, for MEO satellites. We also investigate the impact of the length of orbital arc on the quality of SLR-derived orbits. Hence, 5- and 7-day arcs constitute the best solution, whereas 3-day arcs are of inferior quality due to an insufficient number of SLR observations and 9-day arcs deteriorate the along-track component. The median RMS from the comparison between 7-day orbital arcs determined using SLR data with microwave-based orbits assumes values in the range of 3-4, 11-16, and 15-27 cm in radial, along-track, and cross-track, respectively, for MEO satellites. BeiDou IGSO and QZSS are characterized by RMS values higher by a factor of 8 and 24, respectively, than MEO orbits.

Drift-free solar sail formations in elliptical Sun-synchronous orbits

Science.gov (United States)

Parsay, Khashayar; Schaub, Hanspeter

2017-10-01

To study the spatial and temporal variations of plasma in the highly dynamic environment of the magnetosphere, multiple spacecraft must fly in a formation. The objective for this study is to investigate the feasibility of solar sail formation flying in the Earth-centered, Sun-synchronous orbit regime. The focus of this effort is to enable formation flying for a group of solar sails that maintain a nominally fixed Sun-pointing attitude during formation flight, solely for the purpose of precessing their orbit apse lines Sun-synchronously. A fixed-attitude solar sail formation is motivated by the difficulties in the simultaneous control of orbit and attitude in flying solar sails. First, the secular rates of the orbital elements resulting from the effects of solar radiation pressure (SRP) are determined using averaging theory for a Sun-pointing attitude sail. These averaged rates are used to analytically derive the first-order necessary conditions for a drift-free solar sail formation in Sun-synchronous orbits, assuming a fixed Sun-pointing orientation for each sail in formation. The validity of the first-order necessary conditions are illustrated by designing quasi-periodic relative motions. Next, nonlinear programming is applied to design truly drift-free two-craft solar sail formations. Lastly, analytic expressions are derived to determine the long-term dynamics and sensitivity of the formation with respect to constant attitude errors, uncertainty in orbital elements, and uncertainty in a sail's characteristic acceleration.

Baseline Design and Performance Analysis of Laser Altimeter for Korean Lunar Orbiter

Directory of Open Access Journals (Sweden)

Hyung-Chul Lim

2016-09-01

Full Text Available Korea’s lunar exploration project includes the launching of an orbiter, a lander (including a rover, and an experimental orbiter (referred to as a lunar pathfinder. Laser altimeters have played an important scientific role in lunar, planetary, and asteroid exploration missions since their first use in 1971 onboard the Apollo 15 mission to the Moon. In this study, a laser altimeter was proposed as a scientific instrument for the Korean lunar orbiter, which will be launched by 2020, to study the global topography of the surface of the Moon and its gravitational field and to support other payloads such as a terrain mapping camera or spectral imager. This study presents the baseline design and performance model for the proposed laser altimeter. Additionally, the study discusses the expected performance based on numerical simulation results. The simulation results indicate that the design of system parameters satisfies performance requirements with respect to detection probability and range error even under unfavorable conditions.

Pointer Analysis for JavaScript Programming Tools

DEFF Research Database (Denmark)

Feldthaus, Asger

Tools that can assist the programmer with tasks, such as, refactoring or code navigation, have proven popular for Java, C#, and other programming languages. JavaScript is a widely used programming language, and its users could likewise benefit from such tools, but the dynamic nature of the language...... is an obstacle for the development of these. Because of this, tools for JavaScript have long remained ineffective compared to those for many other programming languages. Static pointer analysis can provide a foundation for more powerful tools, although the design of this analysis is itself a complicated endeavor....... In this work, we explore techniques for performing pointer analysis of JavaScript programs, and we find novel applications of these techniques. In particular, we demonstrate how these can be used for code navigation, automatic refactoring, semi-automatic refactoring of incomplete programs, and checking of type...

TET-1- A German Microsatellite for Technology On -Orbit Verification

Science.gov (United States)

Föckersperger, S.; Lattner, K.; Kaiser, C.; Eckert, S.; Bärwald, W.; Ritzmann, S.; Mühlbauer, P.; Turk, M.; Willemsen, P.

2008-08-01

Due to the high safety standards in the space industry every new product must go through a verification process before qualifying for operation in a space system. Within the verification process the payload undergoes a series of tests which prove that it is in accordance with mission requirements in terms of function, reliability and safety. Important verification components are the qualification for use on the ground as well as the On-Orbit Verification (OOV), i.e. proof that the product is suitable for use under virtual space conditions (on-orbit). Here it is demonstrated that the product functions under conditions which cannot or can only be partially simulated on the ground. The OOV-Program of the DLR serves to bridge the gap between the product tested and qualified on the ground and the utilization of the product in space. Due to regular and short-term availability of flight opportunities industry and research facilities can verify their latest products under space conditions and demonstrate their reliability and marketability. The Technologie-Erprobungs-Tr&äger TET (Technology Experiments Carrier) comprises the core elements of the OOV Program. A programmatic requirement of the OOV Program is that a satellite bus already verified in orbit be used in the first segment of the program. An analysis of suitable satellite buses showed that a realization of the TET satellite bus based on the BIRD satellite bus fulfilled the programmatic requirements best. Kayser-Threde was selected by DLR as Prime Contractor to perform the project together with its major subcontractors Astro- und Feinwerktechnik, Berlin for the platform development and DLR-GSOC for the ground segment development. TET is now designed to be a modular and flexible micro-satellite for any orbit between 450 and 850 km altitude and inclination between 53° and SSO. With an overall mass of 120 kg TET is able to accommodate experiments of up to 50 kg. A multipurpose payload supply systemThere is

Enumeration and stability analysis of simple periodic orbits in β-Fermi Pasta Ulam lattice

International Nuclear Information System (INIS)

Sonone, Rupali L.; Jain, Sudhir R.

2014-01-01

We study the well-known one-dimensional problem of N particles with a nonlinear interaction. The special case of quadratic and quartic interaction potential among nearest neighbours is the β-Fermi-Pasta-Ulam model. We enumerate and classify the simple periodic orbits for this system and find the stability zones, employing Floquet theory. Such stability analysis is crucial to understand the transition of FPU lattice from recurrences to globally chaotic behavior, energy transport in lower dimensional system, dynamics of optical lattices and also its impact on shape parameter of bio-polymers such as DNA and RNA

Enumeration and stability analysis of simple periodic orbits in β-Fermi Pasta Ulam lattice

Energy Technology Data Exchange (ETDEWEB)

Sonone, Rupali L., E-mail: vaidehisonone@gmail.com; Jain, Sudhir R., E-mail: vaidehisonone@gmail.com [Department of Physics, University of Pune, Pune-411007, India and Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085 (India)

2014-04-24

We study the well-known one-dimensional problem of N particles with a nonlinear interaction. The special case of quadratic and quartic interaction potential among nearest neighbours is the β-Fermi-Pasta-Ulam model. We enumerate and classify the simple periodic orbits for this system and find the stability zones, employing Floquet theory. Such stability analysis is crucial to understand the transition of FPU lattice from recurrences to globally chaotic behavior, energy transport in lower dimensional system, dynamics of optical lattices and also its impact on shape parameter of bio-polymers such as DNA and RNA.

Atmospheric interaction with nanosatellites from observed orbital decay

Science.gov (United States)

Macario-Rojas, A.; Smith, K. L.; Crisp, N. H.; Roberts, P. C. E.

2018-06-01

Nanosatellites have gained considerable presence in low Earth orbits wherein the atmospheric interaction with exposed surfaces plays a fundamental role in the evolution of motion. These aspects become relevant with the increasing applicability of nanosatellites to a broader range of missions objectives. This investigation sets out to determine distinctive drag coefficient development and attributes of atmospheric gas-surface interactions in nanosatellites in the common form of standard 3U CubeSats from observed orbital decay. As orbital decay can be measured with relative accuracy, and its mechanism broken down into its constituent sources, the value of drag-related coefficients can be inferred by fitting modelled orbit predictions to observed data wherein the coefficient of interest is the adjusted parameter. The analysis uses the data of ten historical missions with documented passive attitude stabilisation strategies to reduce uncertainties. Findings indicate that it is possible to estimate fitted drag coefficients in CubeSats with physical representativeness. Assessment of atomic oxygen surface coverage derived from the fitted drag coefficients is broadly consistent with theoretical trends. The proposed methodology opens the possibility to assess atmospheric interaction characteristics by using the unprecedented opportunity arising from the numerous observed orbital decay of nanosatellites.

Orbital elements and an analysis of models for HDE 226868 = Cygnus X-1

International Nuclear Information System (INIS)

Bolton, C.T.

1975-01-01

Radial velocities from 21 new high-dispersion spectrograms of HDE 226868 are presented. These are combined with previously published data to calculate a ''definitive'' set of orbital elements for the binary system. In particular, archival data are used to obtain a precise period. The ellipsoidal light curve is analyzed using both a Roche model and an ellipsoidal model, and the results are compared with work by Hutchings. Information from the absorption-line and emission-line velocity curves and the light curve is combined to give estimates for the orbital inclination and the component masses. The possible errors in the analysis are discussed and are shown to be negligible. A qualitative model for the mass transfer is proposed that explains the intensity and velocity variations of the optical emission lines and the variations in the X-ray intensity: including the low-energy X-ray absorption events sometimes seen near superior conjunction of the secondary. Tests of this model are also proposed. Finally, the observations are used to test various models that have been proposed for the system. The observations rule out low mass and rotating degenerate dwarf secondaries and present difficulties for the triple star model. The magnetic reconnection model is not ruled out by the observations. Models in which the secondary is a black hole are consistent with all available observations

Nontraumatic orbital roof encephalocele.

Science.gov (United States)

Hoang, Amber; Maugans, Todd; Ngo, Thang; Ikeda, Jamie

2017-02-01

Intraorbital meningoencephaloceles occur most commonly as a complication of traumatic orbital roof fractures. Nontraumatic congenital orbital meningoncephaloceles are very rare, with most secondary to destructive processes affecting the orbit and primary skull defects. Treatment for intraorbital meningoencephaloceles is surgical repair, involving the excision of herniated brain parenchyma and meninges and reconstruction of the osseous defect. Most congenital lesions present in infancy with obvious globe and orbital deformities; we report an orbital meningoencephalocele in a 3-year-old girl who presented with ptosis. Copyright © 2017 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Biodiesel Emissions Analysis Program

Science.gov (United States)

Using existing data, the EPA's biodiesel emissions analysis program sought to quantify the air pollution emission effects of biodiesel for diesel engines that have not been specifically modified to operate on biodiesel.

Mean-field study of correlation-induced antisymmetric spin-orbit coupling in a two-orbital honeycomb model

Science.gov (United States)

Hayami, Satoru; Kusunose, Hiroaki; Motome, Yukitoshi

2018-05-01

We investigate a two-orbital Hubbard model on a honeycomb structure, with a special focus on the antisymmetric spin-orbit coupling (ASOC) induced by symmetry breaking in the electronic degrees of freedom. By investigating the ground-state phase diagram by the mean-field approximation in addition to the analysis in the strong correlation limit, we obtain a variety of symmetry-broken phases that induce different types of effective ASOCs by breaking of spatial inversion symmetry. We find several unusual properties emergent from the ASOCs, such as a linear magnetoelectric effect in a spin-orbital ordered phase at 1/4 filling and a spin splitting in the band structure in charge ordered phases at 1/4 and 1/2 fillings. We also show that a staggered potential on the honeycomb structure leads to another type of ASOC, which gives rise to a valley splitting in the band structure at 1/2 filling. We discuss the experimental relevance of our results to candidate materials including transition metal dichalcogenides and trichalcogenides.

E-Orbit Functions

Directory of Open Access Journals (Sweden)

Jiri Patera

2008-01-01

Full Text Available We review and further develop the theory of $E$-orbit functions. They are functions on the Euclidean space $E_n$ obtained from the multivariate exponential function by symmetrization by means of an even part $W_{e}$ of a Weyl group $W$, corresponding to a Coxeter-Dynkin diagram. Properties of such functions are described. They are closely related to symmetric and antisymmetric orbit functions which are received from exponential functions by symmetrization and antisymmetrization procedure by means of a Weyl group $W$. The $E$-orbit functions, determined by integral parameters, are invariant withrespect to even part $W^{aff}_{e}$ of the affine Weyl group corresponding to $W$. The $E$-orbit functions determine a symmetrized Fourier transform, where these functions serve as a kernel of the transform. They also determine a transform on a finite set of points of the fundamental domain $F^{e}$ of the group $W^{aff}_{e}$ (the discrete $E$-orbit function transform.

Modeling and analysis of periodic orbits around a contact binary asteroid

Science.gov (United States)

Feng, Jinglang; Noomen, Ron; Visser, Pieter N. A. M.; Yuan, Jianping

2015-06-01

The existence and characteristics of periodic orbits (POs) in the vicinity of a contact binary asteroid are investigated with an averaged spherical harmonics model. A contact binary asteroid consists of two components connected to each other, resulting in a highly bifurcated shape. Here, it is represented by a combination of an ellipsoid and a sphere. The gravitational field of this configuration is for the first time expanded into a spherical harmonics model up to degree and order 8. Compared with the exact potential, the truncation at degree and order 4 is found to introduce an error of less than 10 % at the circumscribing sphere and less than 1 % at a distance of the double of the reference radius. The Hamiltonian taking into account harmonics up to degree and order 4 is developed. After double averaging of this Hamiltonian, the model is reduced to include zonal harmonics only and frozen orbits are obtained. The tesseral terms are found to introduce significant variations on the frozen orbits and distort the frozen situation. Applying the method of Poincaré sections, phase space structures of the single-averaged model are generated for different energy levels and rotation rates of the asteroid, from which the dynamics driven by the 4×4 harmonics model is identified and POs are found. It is found that the disturbing effect of the highly irregular gravitational field on orbital motion is weakened around the polar region, and also for an asteroid with a fast rotation rate. Starting with initial conditions from this averaged model, families of exact POs in the original non-averaged system are obtained employing a numerical search method and a continuation technique. Some of these POs are stable and are candidates for future missions.

Congenital orbital encephalocele, orbital dystopia, and exophthalmos.

Science.gov (United States)

Hwang, Kun; Kim, Han Joon

2012-07-01

We present here an exceedingly rare variant of a nonmidline basal encephalocele of the spheno-orbital type, and this was accompanied with orbital dystopia in a 56-year-old man. On examination, his left eye was located more inferolaterally than his right eye, and the patient said this had been this way since his birth. The protrusion of his left eye was aggravated when he is tired. His naked visual acuity was 0.7/0.3, and the ocular pressure was 14/12 mm Hg. The exophthalmometry was 10/14 to 16 mm. His eyeball motion was not restricted, yet diplopia was present in all directions. The distance from the midline to the medial canthus was 20/15 mm. The distance from the midline to the midpupillary line was 35/22 mm. The vertical dimension of the palpebral fissure was 12/9 mm. The height difference of the upper eyelid margin was 11 mm, and the height difference of the lower eyelid margin was 8 mm. Facial computed tomography and magnetic resonance imaging showed left sphenoid wing hypoplasia and herniation of the left anterior temporal pole and dura mater into the orbit, and this resulted into left exophthalmos and encephalomalacia in the left anterior temporal pole. To the best of our knowledge, our case is the second case of basal encephalocele and orbital dystopia.

Benefits of high aerodynamic efficiency to orbital transfer vehicles

Science.gov (United States)

Andrews, D. G.; Norris, R. B.; Paris, S. W.

1984-01-01

The benefits and costs of high aerodynamic efficiency on aeroassisted orbital transfer vehicles (AOTV) are analyzed. Results show that a high lift to drag (L/D) AOTV can achieve significant velocity savings relative to low L/D aerobraked OTV's when traveling round trip between low Earth orbits (LEO) and alternate orbits as high as geosynchronous Earth orbit (GEO). Trajectory analysis is used to show the impact of thermal protection system technology and the importance of lift loading coefficient on vehicle performance. The possible improvements in AOTV subsystem technologies are assessed and their impact on vehicle inert weight and performance noted. Finally, the performance of high L/D AOTV concepts is compared with the performances of low L/D aeroassisted and all propulsive OTV concepts to assess the benefits of aerodynamic efficiency on this class of vehicle.

Measurement of orbital volume by computed tomography. Especially on the growth of orbit

Energy Technology Data Exchange (ETDEWEB)

Furuta, Minoru [Fukushima Medical Coll. (Japan)

2000-10-01

Using reconstructed X-ray computed tomography (CT) images of serial coronal sections, we measured the orbital volume and studied its changes with age. The subjects consisted of 109 patients (74 males, 35 females) who had undergone X-ray CT. After the reproducibility of orbital volume measurements and laterality in individuals were confirmed, the relation between the orbital volume and the age, sex, weight, and interlateral orbital rim distance were examined. The difference between two measurements in the same patients was 0.4% for measured volume, which showed the reproducibility of this measurement to be good. The laterality in individuals was 0.06 cm{sup 3}: this difference was very small and not significant. The orbital volume showed no unbalance between the right and left at any stage of growth. Both the height and the interlateral orbital rim distance had a strong correlation with the orbital volume. Referring to the relation between age and orbital volume, a strong correlation with an almost identical approximate equation was obtained for both sexes under 12 years of age. Presumably, the rapid growth of the orbit comes to an end by 15 years of age in males and 11 years in females. This means that more than 95% growth of adults has already been completed in the first half of the teens. The mean orbital volume in adult Japanese is 23.6{+-}2.0 (mean{+-}standard deviation) cm{sup 3} in males and 20.9{+-}1.3 cm{sup 3} in females. (author)

Measurement of orbital volume by computed tomography. Especially on the growth of orbit

International Nuclear Information System (INIS)

Furuta, Minoru

2000-01-01

Using reconstructed X-ray computed tomography (CT) images of serial coronal sections, we measured the orbital volume and studied its changes with age. The subjects consisted of 109 patients (74 males, 35 females) who had undergone X-ray CT. After the reproducibility of orbital volume measurements and laterality in individuals were confirmed, the relation between the orbital volume and the age, sex, weight, and interlateral orbital rim distance were examined. The difference between two measurements in the same patients was 0.4% for measured volume, which showed the reproducibility of this measurement to be good. The laterality in individuals was 0.06 cm 3 : this difference was very small and not significant. The orbital volume showed no unbalance between the right and left at any stage of growth. Both the height and the interlateral orbital rim distance had a strong correlation with the orbital volume. Referring to the relation between age and orbital volume, a strong correlation with an almost identical approximate equation was obtained for both sexes under 12 years of age. Presumably, the rapid growth of the orbit comes to an end by 15 years of age in males and 11 years in females. This means that more than 95% growth of adults has already been completed in the first half of the teens. The mean orbital volume in adult Japanese is 23.6±2.0 (mean±standard deviation) cm 3 in males and 20.9±1.3 cm 3 in females. (author)

Coulomb-free and Coulomb-distorted recolliding quantum orbits in photoelectron holography

Science.gov (United States)

Maxwell, A. S.; Figueira de Morisson Faria, C.

2018-06-01

We perform a detailed analysis of the different types of orbits in the Coulomb quantum orbit strong-field approximation (CQSFA), ranging from direct to those undergoing hard collisions. We show that some of them exhibit clear counterparts in the standard formulations of the strong-field approximation for direct and rescattered above-threshold ionization, and show that the standard orbit classification commonly used in Coulomb-corrected models is over-simplified. We identify several types of rescattered orbits, such as those responsible for the low-energy structures reported in the literature, and determine the momentum regions in which they occur. We also find formerly overlooked interference patterns caused by backscattered Coulomb-corrected orbits and assess their effect on photoelectron angular distributions. These orbits improve the agreement of photoelectron angular distributions computed with the CQSFA with the outcome of ab initio methods for high energy phtotoelectrons perpendicular to the field polarization axis.

Probabilistic Structural Analysis Program

Science.gov (United States)

Pai, Shantaram S.; Chamis, Christos C.; Murthy, Pappu L. N.; Stefko, George L.; Riha, David S.; Thacker, Ben H.; Nagpal, Vinod K.; Mital, Subodh K.

2010-01-01

NASA/NESSUS 6.2c is a general-purpose, probabilistic analysis program that computes probability of failure and probabilistic sensitivity measures of engineered systems. Because NASA/NESSUS uses highly computationally efficient and accurate analysis techniques, probabilistic solutions can be obtained even for extremely large and complex models. Once the probabilistic response is quantified, the results can be used to support risk-informed decisions regarding reliability for safety-critical and one-of-a-kind systems, as well as for maintaining a level of quality while reducing manufacturing costs for larger-quantity products. NASA/NESSUS has been successfully applied to a diverse range of problems in aerospace, gas turbine engines, biomechanics, pipelines, defense, weaponry, and infrastructure. This program combines state-of-the-art probabilistic algorithms with general-purpose structural analysis and lifting methods to compute the probabilistic response and reliability of engineered structures. Uncertainties in load, material properties, geometry, boundary conditions, and initial conditions can be simulated. The structural analysis methods include non-linear finite-element methods, heat-transfer analysis, polymer/ceramic matrix composite analysis, monolithic (conventional metallic) materials life-prediction methodologies, boundary element methods, and user-written subroutines. Several probabilistic algorithms are available such as the advanced mean value method and the adaptive importance sampling method. NASA/NESSUS 6.2c is structured in a modular format with 15 elements.

Orbit Clustering Based on Transfer Cost

Science.gov (United States)

Gustafson, Eric D.; Arrieta-Camacho, Juan J.; Petropoulos, Anastassios E.

2013-01-01

We propose using cluster analysis to perform quick screening for combinatorial global optimization problems. The key missing component currently preventing cluster analysis from use in this context is the lack of a useable metric function that defines the cost to transfer between two orbits. We study several proposed metrics and clustering algorithms, including k-means and the expectation maximization algorithm. We also show that proven heuristic methods such as the Q-law can be modified to work with cluster analysis.

Low-Cost 3D Printing Orbital Implant Templates in Secondary Orbital Reconstructions.

Science.gov (United States)

Callahan, Alison B; Campbell, Ashley A; Petris, Carisa; Kazim, Michael

Despite its increasing use in craniofacial reconstructions, three-dimensional (3D) printing of customized orbital implants has not been widely adopted. Limitations include the cost of 3D printers able to print in a biocompatible material suitable for implantation in the orbit and the breadth of available implant materials. The authors report the technique of low-cost 3D printing of orbital implant templates used in complex, often secondary, orbital reconstructions. A retrospective case series of 5 orbital reconstructions utilizing a technique of 3D printed orbital implant templates is presented. Each patient's Digital Imaging and Communications in Medicine data were uploaded and processed to create 3D renderings upon which a customized implant was designed and sent electronically to printers open for student use at our affiliated institutions. The mock implants were sterilized and used intraoperatively as a stencil and mold. The final implant material was chosen by the surgeons based on the requirements of the case. Five orbital reconstructions were performed with this technique: 3 tumor reconstructions and 2 orbital fractures. Four of the 5 cases were secondary reconstructions. Molded Medpor Titan (Stryker, Kalamazoo, MI) implants were used in 4 cases and titanium mesh in 1 case. The stenciled and molded implants were adjusted no more than 2 times before anchored in place (mean 1). No case underwent further revision. The technique and cases presented demonstrate 1) the feasibility and accessibility of low-cost, independent use of 3D printing technology to fashion patient-specific implants in orbital reconstructions, 2) the ability to apply this technology to the surgeon's preference of any routinely implantable material, and 3) the utility of this technique in complex, secondary reconstructions.

The analysis of single-electron orbits in a free electron laser based upon a rectangular hybrid wiggler

International Nuclear Information System (INIS)

Kordbacheh, A.; Ghahremaninezhad, Roghayeh; Maraghechi, B.

2012-01-01

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.

The analysis of single-electron orbits in a free electron laser based upon a rectangular hybrid wiggler

Science.gov (United States)

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.

Isospin dependence of the spin-orbit splitting in nuclei

International Nuclear Information System (INIS)

Isakov, V.I.

2007-01-01

The analysis has been made of experimental data on level spectra, single-nucleon transfer reactions near closed shells, and data on polarization effects in charge-exchange (p, n) reactions between isoanalogous states of nuclei with even A. It is concluded that there is a significant difference between the spin-orbit splittings of neutrons and protons in identical orbitals. This conclusion is confirmed in the frame work of different theoretical approaches [ru

Stable low-altitude orbits around Ganymede considering a disturbing body in a circular orbit

Science.gov (United States)

Cardoso dos Santos, J.; Carvalho, J. P. S.; Vilhena de Moraes, R.

2014-10-01

Some missions are being planned to visit Ganymede like the Europa Jupiter System Mission that is a cooperation between NASA and ESA to insert the spacecraft JGO (Jupiter Ganymede Orbiter) into Ganymedes orbit. This comprehension of the dynamics of these orbits around this planetary satellite is essential for the success of this type of mission. Thus, this work aims to perform a search for low-altitude orbits around Ganymede. An emphasis is given in polar orbits and it can be useful in the planning of space missions to be conducted around, with respect to the stability of orbits of artificial satellites. The study considers orbits of artificial satellites around Ganymede under the influence of the third-body (Jupiter's gravitational attraction) and the polygenic perturbations like those due to non-uniform distribution of mass (J_2 and J_3) of the main body. A simplified dynamic model for these perturbations is used. The Lagrange planetary equations are used to describe the orbital motion of the artificial satellite. The equations of motion are developed in closed form to avoid expansions in eccentricity and inclination. The results show the argument of pericenter circulating. However, low-altitude (100 and 150 km) polar orbits are stable. Another orbital elements behaved variating with small amplitudes. Thus, such orbits are convenient to be applied to future space missions to Ganymede. Acknowledgments: FAPESP (processes n° 2011/05671-5, 2012/12539-9 and 2012/21023-6).

Titan Orbiter Aerorover Mission

Science.gov (United States)

Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

2001-01-01

We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

Inspection of the Math Model Tools for On-Orbit Assessment of Impact Damage Report

Science.gov (United States)

Harris, Charles E.; Raju, Ivatury S.; Piascik, Robert S> KramerWhite, Julie A.; KramerWhite, Julie A.; Labbe, Steve G.; Rotter, Hank A.

2007-01-01

In Spring of 2005, the NASA Engineering Safety Center (NESC) was engaged by the Space Shuttle Program (SSP) to peer review the suite of analytical tools being developed to support the determination of impact and damage tolerance of the Orbiter Thermal Protection Systems (TPS). The NESC formed an independent review team with the core disciplines of materials, flight sciences, structures, mechanical analysis and thermal analysis. The Math Model Tools reviewed included damage prediction and stress analysis, aeroheating analysis, and thermal analysis tools. Some tools are physics-based and other tools are empirically-derived. Each tool was created for a specific use and timeframe, including certification, real-time pre-launch assessments. In addition, the tools are used together in an integrated strategy for assessing the ramifications of impact damage to tile and RCC. The NESC teams conducted a peer review of the engineering data package for each Math Model Tool. This report contains the summary of the team observations and recommendations from these reviews.

Harmonically excited orbital variations

International Nuclear Information System (INIS)

Morgan, T.

1985-01-01

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs

The nuclear analysis program at MURR

International Nuclear Information System (INIS)

Glascock, M.D.

1993-01-01

The University of Missouri-Columbia (MU) has continually upgraded research facilities and programs at the MU research reactor (MURR) throughout its 26-yr history. The Nuclear Analysis Program (NAP) area has participated in these upgrades over the years. As one of the largest activation analysis laboratories on a university campus, the activities of the NAP are broadly representative of the diversity of applications for activation analysis and related nuclear science. This paper describes the MURR's NAP and several of the research, education, and service projects in which the laboratory is currently engaged

Shuttle Orbiter Active Thermal Control Subsystem design and flight experience

Science.gov (United States)

Bond, Timothy A.; Metcalf, Jordan L.; Asuncion, Carmelo

1991-01-01

The paper examines the design of the Space Shuttle Orbiter Active Thermal Control Subsystem (ATCS) constructed for providing the vehicle and payload cooling during all phases of a mission and during ground turnaround operations. The operation of the Shuttle ATCS and some of the problems encountered during the first 39 flights of the Shuttle program are described, with special attention given to the major problems encountered with the degradation of the Freon flow rate on the Orbiter Columbia, the Flash Evaporator Subsystem mission anomalies which occurred on STS-26 and STS-34, and problems encountered with the Ammonia Boiler Subsystem. The causes and the resolutions of these problems are discussed.

Program Analysis and Its Relevance for Educational Research

Directory of Open Access Journals (Sweden)

Bernd Käpplinger

2008-01-01

Full Text Available Program analyses are frequently used in research on continuing education. The use of such analyses will be described in this article. Existing data sources, research topics, qualitative, quantitative and mixed methods, will be discussed. Three types of program analysis will be developed. The article ends with a discussion of the advantages and disadvantages of program analysis in contrast to questionnaires. Future developments and challenges will be sketched in the conclusion. Recommendations for the future development of program analysis will be given. URN: urn:nbn:de:0114-fqs0801379

Development Status of the WetLab-2 Project: New Tools for On-orbit Real-time Quantitative Gene Expression.

Science.gov (United States)

Jung, Jimmy; Parra, Macarena P.; Almeida, Eduardo; Boone, Travis; Chinn, Tori; Ricco, Antonio; Souza, Kenneth; Hyde, Liz; Rukhsana, Yousuf; Richey, C. Scott

2013-01-01

The primary objective of NASA Ames Research Centers WetLab-2 Project is to place on the ISS a research platform to facilitate gene expression analysis via quantitative real-time PCR (qRT-PCR) of biological specimens grown or cultured on orbit. The WetLab-2 equipment will be capable of processing multiple sample types ranging from microbial cultures to animal tissues dissected on-orbit. In addition to the logistical benefits of in-situ sample processing and analysis, conducting qRT-PCR on-orbit eliminates the confounding effects on gene expression of reentry stresses and shock acting on live cells and organisms. The system can also validate terrestrial analyses of samples returned from ISS by providing quantitative on-orbit gene expression benchmarking prior to sample return. The ability to get on orbit data will provide investigators with the opportunity to adjust experimental parameters for subsequent trials based on the real-time data analysis without need for sample return and re-flight. Finally, WetLab-2 can be used for analysis of air, surface, water, and clinical samples to monitor environmental contaminants and crew health. The verification flight of the instrument is scheduled to launch on SpaceX-5 in Aug. 2014.Progress to date: The WetLab-2 project completed a thorough study of commercially available qRT-PCR systems and performed a downselect based on both scientific and engineering requirements. The selected instrument, the Cepheid SmartCycler, has advantages including modular design (16 independent PCR modules), low power consumption, and rapid ramp times. The SmartCycler has multiplex capabilities, assaying up to four genes of interest in each of the 16 modules. The WetLab-2 team is currently working with Cepheid to modify the unit for housing within an EXPRESS rack locker on the ISS. This will enable the downlink of data to the ground and provide uplink capabilities for programming, commanding, monitoring, and instrument maintenance. The project is

Lissajous orbit acquisition and interpretation in relation to vibration analysis

International Nuclear Information System (INIS)

Ahmed, S.; Mahmood, A.; Bibi, A.; Shehzad, K.; Zahoor, Y.

2001-01-01

In resent years, it has become common practice to install dual non-contacting eddy current probes on critical high-speed turbo-machinery to avoid false shutdowns in the events that one of the probes should fail. The pickups are mounted radially in each bearing with the axis of the pickups separated by 90 deg. Some are mounted in the horizontal or vertical directions; others are mounted on an axis 45 deg. from the horizontal '10:30' and '1:30' clock positions. These same non contacting pickups can be hooked into an oscilloscope to provide Lissajous orbit patterns of the shaft's motion in the bearing. This text will deal with proper setup of the transducers and instrumentation required to produce Lissajous orbits. Some examples Lissajous are given and their the diagnosis of common machine problems is provided. The interpretation of JS plots will be the highlight of this text. (author)

Space Shuttle OMS engine valve technology. [Orbital Maneuvering System

Science.gov (United States)

Wichmann, H.

1974-01-01

Valve technology program to determine shutoff valve concepts suitable for the Orbital Maneuvering System (OMS) engine of the Space Shuttle. The tradeoff studies selected the electric torque motor operated dual poppet and ball valves as the most desirable valve concepts for the OMS Engine Shutoff Valve. A prototype of one of these concepts was built and subjected to a design verification program. A number of unique features were designed to include the required contamination insensitivity, operating fluid compatibility, decontamination capability, minimum maintenance requirement and long service life capability.

Spin-orbit torques from interfacial spin-orbit coupling for various interfaces

Science.gov (United States)

Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M. D.

2017-09-01

We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal-metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism.

Orbit-attitude coupled motion around small bodies: Sun-synchronous orbits with Sun-tracking attitude motion

Science.gov (United States)

Kikuchi, Shota; Howell, Kathleen C.; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

2017-11-01

The motion of a spacecraft in proximity to a small body is significantly perturbed due to its irregular gravity field and solar radiation pressure. In such a strongly perturbed environment, the coupling effect of the orbital and attitude motions exerts a large influence that cannot be neglected. However, natural orbit-attitude coupled dynamics around small bodies that are stationary in both orbital and attitude motions have yet to be observed. The present study therefore investigates natural coupled motion that involves both a Sun-synchronous orbit and Sun-tracking attitude motion. This orbit-attitude coupled motion enables a spacecraft to maintain its orbital geometry and attitude state with respect to the Sun without requiring active control. Therefore, the proposed method can reduce the use of an orbit and attitude control system. This paper first presents analytical conditions to achieve Sun-synchronous orbits and Sun-tracking attitude motion. These analytical solutions are then numerically propagated based on non-linear coupled orbit-attitude equations of motion. Consequently, the possibility of implementing Sun-synchronous orbits with Sun-tracking attitude motion is demonstrated.

Integrating computer programs for engineering analysis and design

Science.gov (United States)

Wilhite, A. W.; Crisp, V. K.; Johnson, S. C.

1983-01-01

The design of a third-generation system for integrating computer programs for engineering and design has been developed for the Aerospace Vehicle Interactive Design (AVID) system. This system consists of an engineering data management system, program interface software, a user interface, and a geometry system. A relational information system (ARIS) was developed specifically for the computer-aided engineering system. It is used for a repository of design data that are communicated between analysis programs, for a dictionary that describes these design data, for a directory that describes the analysis programs, and for other system functions. A method is described for interfacing independent analysis programs into a loosely-coupled design system. This method emphasizes an interactive extension of analysis techniques and manipulation of design data. Also, integrity mechanisms exist to maintain database correctness for multidisciplinary design tasks by an individual or a team of specialists. Finally, a prototype user interface program has been developed to aid in system utilization.

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

Science.gov (United States)

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.

Congenital orbital teratoma

OpenAIRE

Aiyub, Shereen; Chan, Weng Onn; Szetu, John; Sullivan, Laurence J; Pater, John; Cooper, Peter; Selva, Dinesh

2013-01-01

We present a case of mature congenital orbital teratoma managed with lid-sparing exenteration and dermis fat graft. This is a case report on the management of congenital orbital teratoma. A full-term baby was born in Fiji with prolapsed right globe which was surrounded by a nonpulsatile, cystic mass. Clinical and imaging features were consistent with congenital orbital teratoma. Due to limited surgical expertise, the patient was transferred to Adelaide, Australia for further management. The p...

The solar neighborhood. XXXIV. A search for planets orbiting nearby M dwarfs using astrometry

International Nuclear Information System (INIS)

Lurie, John C.; Henry, Todd J.; Ianna, Philip A.; Jao, Wei-Chun; Quinn, Samuel N.; Winters, Jennifer G.; Koerner, David W.; Riedel, Adric R.; Subasavage, John P.

2014-01-01

Astrometric measurements are presented for seven nearby stars with previously detected planets: six M dwarfs (GJ 317, GJ 667C, GJ 581, GJ 849, GJ 876, and GJ 1214) and one K dwarf (BD-10 -3166). Measurements are also presented for six additional nearby M dwarfs without known planets, but which are more favorable to astrometric detections of low mass companions, as well as three binary systems for which we provide astrometric orbit solutions. Observations have baselines of 3 to 13 years, and were made as part of the RECONS long-term astrometry and photometry program at the CTIO/SMARTS 0.9 m telescope. We provide trigonometric parallaxes and proper motions for all 16 systems, and perform an extensive analysis of the astrometric residuals to determine the minimum detectable companion mass for the 12 M dwarfs not having close stellar secondaries. For the six M dwarfs with known planets, we are not sensitive to planets, but can rule out the presence of all but the least massive brown dwarfs at periods of 2–12 years. For the six more astrometrically favorable M dwarfs, we conclude that none have brown dwarf companions, and are sensitive to companions with masses as low as 1 M Jup for periods longer than two years. In particular, we conclude that Proxima Centauri has no Jovian companions at orbital periods of 2–12 years. These results complement previously published M dwarf planet occurrence rates by providing astrometrically determined upper mass limits on potential super-Jupiter companions at orbits of two years and longer. As part of a continuing survey, these results are consistent with the paucity of super-Jupiter and brown dwarf companions we find among the over 250 red dwarfs within 25 pc observed longer than five years in our astrometric program.

The solar neighborhood. XXXIV. A search for planets orbiting nearby M dwarfs using astrometry

Energy Technology Data Exchange (ETDEWEB)

Lurie, John C. [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Henry, Todd J.; Ianna, Philip A. [RECONS Institute, Chambersburg, PA 17201 (United States); Jao, Wei-Chun; Quinn, Samuel N.; Winters, Jennifer G. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302 (United States); Koerner, David W. [Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ 86011 (United States); Riedel, Adric R. [Department of Astrophysics, American Museum of Natural History, New York, NY 10034 (United States); Subasavage, John P., E-mail: lurie@uw.edu [United States Naval Observatory, Flagstaff, AZ 86001 (United States)

2014-11-01

Astrometric measurements are presented for seven nearby stars with previously detected planets: six M dwarfs (GJ 317, GJ 667C, GJ 581, GJ 849, GJ 876, and GJ 1214) and one K dwarf (BD-10 -3166). Measurements are also presented for six additional nearby M dwarfs without known planets, but which are more favorable to astrometric detections of low mass companions, as well as three binary systems for which we provide astrometric orbit solutions. Observations have baselines of 3 to 13 years, and were made as part of the RECONS long-term astrometry and photometry program at the CTIO/SMARTS 0.9 m telescope. We provide trigonometric parallaxes and proper motions for all 16 systems, and perform an extensive analysis of the astrometric residuals to determine the minimum detectable companion mass for the 12 M dwarfs not having close stellar secondaries. For the six M dwarfs with known planets, we are not sensitive to planets, but can rule out the presence of all but the least massive brown dwarfs at periods of 2–12 years. For the six more astrometrically favorable M dwarfs, we conclude that none have brown dwarf companions, and are sensitive to companions with masses as low as 1 M{sub Jup} for periods longer than two years. In particular, we conclude that Proxima Centauri has no Jovian companions at orbital periods of 2–12 years. These results complement previously published M dwarf planet occurrence rates by providing astrometrically determined upper mass limits on potential super-Jupiter companions at orbits of two years and longer. As part of a continuing survey, these results are consistent with the paucity of super-Jupiter and brown dwarf companions we find among the over 250 red dwarfs within 25 pc observed longer than five years in our astrometric program.

Implementation of the Orbital Maneuvering Systems Engine and Thrust Vector Control for the European Service Module

Science.gov (United States)

Millard, Jon

2014-01-01

The European Space Agency (ESA) has entered into a partnership with the National Aeronautics and Space Administration (NASA) to develop and provide the Service Module (SM) for the Orion Multipurpose Crew Vehicle (MPCV) Program. The European Service Module (ESM) will provide main engine thrust by utilizing the Space Shuttle Program Orbital Maneuvering System Engine (OMS-E). Thrust Vector Control (TVC) of the OMS-E will be provided by the Orbital Maneuvering System (OMS) TVC, also used during the Space Shuttle Program. NASA will be providing the OMS-E and OMS TVC to ESA as Government Furnished Equipment (GFE) to integrate into the ESM. This presentation will describe the OMS-E and OMS TVC and discuss the implementation of the hardware for the ESM.

Orbital atherectomy for treating de novo, severely calcified coronary lesions: 3-year results of the pivotal ORBIT II trial.

Science.gov (United States)

Lee, Michael; Généreux, Philippe; Shlofmitz, Richard; Phillipson, Daniel; Anose, Bynthia M; Martinsen, Brad J; Himmelstein, Stevan I; Chambers, Jeff W

2017-06-01

The presence of heavy coronary artery calcification increases the complexity of percutaneous coronary intervention (PCI) and increases the incidence of major adverse cardiac events (MACE): death, myocardial infarction (MI), target vessel revascularization (TVR), and stent thrombosis. The ORBIT II (Evaluate the Safety and Efficacy of OAS in Treating Severely Calcified Coronary Lesions) trial reported low rates of procedural, 30-day, 1-year, and 2-year ischemic complications after treatment of de novo, severely calcified lesions with the Diamondback 360° Coronary Orbital Atherectomy System (OAS) (Cardiovascular Systems, Inc.). ORBIT II was a single-arm trial that enrolled 443 patients at 49U.S. sites; in this study, de novo, severely calcified coronary lesions were treated with OAS prior to stenting. The primary safety endpoint was 30-day MACE: the composite of cardiac death, MI, and TVR (inclusive of target lesion revascularization (TLR)). The primary efficacy endpoint was procedural success: stent delivery with a residual stenosis of atherectomy. There were 360 (81.3%) subjects who completed the protocol-mandated 3-year visit.The overall cumulative rate of 3-year MACE was 23.5%, including cardiac death (6.7%), MI (11.2%), and TVR (10.2%). The 3-year target lesion revascularization rate was 7.8%. In the final 3-year analysis of the ORBIT II trial, orbital atherectomy of severely calcified coronary lesions followed by stenting resulted in a low rate of adverse ischemic events compared with historical controls.Orbital atherectomy represents a safe and effective revascularization strategy for patients with severely calcified coronary lesions. The ORBIT II trial enrolled 443 subjects to study orbital atherectomy followed by stenting for de novo severely calcified coronary lesions. The overall cumulative 3-year MACE rate was 23.5%, including cardiac death (6.7%), MI (11.2%), and TVR (10.2%); the 3-year target lesion revascularization rate was 7.8%. Orbital atherectomy

Status of CHAP: composite HTGR analysis program

International Nuclear Information System (INIS)

Secker, P.A.; Gilbert, J.S.

1975-12-01

Development of an HTGR accident simulation program is in progress for the prediction of the overall HTGR plant transient response to various initiating events. The status of the digital computer program named CHAP (Composite HTGR Analysis Program) as of June 30, 1975, is given. The philosophy, structure, and capabilities of the CHAP code are discussed. Mathematical descriptions are given for those HTGR components that have been modeled. Component model validation and evaluation using auxiliary analysis codes are also discussed

NASA Orbital Debris Large-Object Baseline Population in ORDEM 3.0

Science.gov (United States)

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.

Single-shell tank retrieval program mission analysis report

Energy Technology Data Exchange (ETDEWEB)

Stokes, W.J.

1998-08-11

This Mission Analysis Report was prepared to provide the foundation for the Single-Shell Tank (SST) Retrieval Program, a new program responsible for waste removal for the SSTS. The SST Retrieval Program is integrated with other Tank Waste Remediation System activities that provide the management, technical, and operations elements associated with planning and execution of SST and SST Farm retrieval and closure. This Mission Analysis Report provides the basis and strategy for developing a program plan for SST retrieval. This Mission Analysis Report responds to a US Department of Energy request for an alternative single-shell tank retrieval approach (Taylor 1997).

Single-shell tank retrieval program mission analysis report

International Nuclear Information System (INIS)

Stokes, W.J.

1998-01-01

This Mission Analysis Report was prepared to provide the foundation for the Single-Shell Tank (SST) Retrieval Program, a new program responsible for waste removal for the SSTS. The SST Retrieval Program is integrated with other Tank Waste Remediation System activities that provide the management, technical, and operations elements associated with planning and execution of SST and SST Farm retrieval and closure. This Mission Analysis Report provides the basis and strategy for developing a program plan for SST retrieval. This Mission Analysis Report responds to a US Department of Energy request for an alternative single-shell tank retrieval approach (Taylor 1997)

Topology of tokamak orbits

International Nuclear Information System (INIS)

Rome, J.A.; Peng, Y.K.M.

1978-09-01

Guiding center orbits in noncircular axisymmetric tokamak plasmas are studied in the constants of motion (COM) space of (v, zeta, psi/sub m/). Here, v is the particle speed, zeta is the pitch angle with respect to the parallel equilibrium current, J/sub parallels/, and psi/sub m/ is the maximum value of the poloidal flux function (increasing from the magnetic axis) along the guiding center orbit. Two D-shaped equilibria in a flux-conserving tokamak having β's of 1.3% and 7.7% are used as examples. In this space, each confined orbit corresponds to one and only one point and different types of orbits (e.g., circulating, trapped, stagnation and pinch orbits) are represented by separate regions or surfaces in the space. It is also shown that the existence of an absolute minimum B in the higher β (7.7%) equilibrium results in a dramatically different orbit topology from that of the lower β case. The differences indicate the confinement of additional high energy (v → c, within the guiding center approximation) trapped, co- and countercirculating particles whose orbit psi/sub m/ falls within the absolute B well

Orbiter/carrier separation for the ALT free flight no. 1 reference trajectories. Mission planning, mission analysis and software formulation

Science.gov (United States)

Glenn, G. M.

1976-01-01

Details of the generation of the separation trajectories are discussed. The analysis culminated in definition of separation trajectories between physical separation and orbiter/carrier vortex clearance. Specifications, assumptions and analytical approach used to generate the separation trajectories are presented. Results of the analytical approach are evaluated. Conclusions and recommendations are summarized. Supporting references are listed.

Orbit selection of nanosatellite formation in term of fuel consumption

Science.gov (United States)

Pimnoo, Ammarin; Hiraki, Koju

In nanosatellite formation mission design, orbit selection is a necessary factor. Fuel consumption is also necessary to maintain the orbit. Therefore, the best orbit should be the one of minimum fuel consumption for nanosatellite formation. The purpose of this paper is to provide a convenient way to estimate fuel consumption for a nanosatellite to keep formation flying. The formation is disturbed by J _{2} perturbation and other perturbing accelerations. Firstly, the Hill-Clohessy-Wiltshire equations are used in the analysis. Gaussian variation of parameters is included into the Hill’s equation to analyze the variation of Kaplerian orbital elements. The J _{2} perturbation and other perturbing accelerations such as atmospheric drag, solar-radiation pressure and third-body perturbations are considered. Thus, a linear model based on Hill’s equation is established to estimate fuel consumption. Finally, an example of the best orbit for formation flying with minimum fuel consumption shall be presented.

Plato: A localised orbital based density functional theory code

Science.gov (United States)

Kenny, S. D.; Horsfield, A. P.

2009-12-01

The Plato package allows both orthogonal and non-orthogonal tight-binding as well as density functional theory (DFT) calculations to be performed within a single framework. The package also provides extensive tools for analysing the results of simulations as well as a number of tools for creating input files. The code is based upon the ideas first discussed in Sankey and Niklewski (1989) [1] with extensions to allow high-quality DFT calculations to be performed. DFT calculations can utilise either the local density approximation or the generalised gradient approximation. Basis sets from minimal basis through to ones containing multiple radial functions per angular momenta and polarisation functions can be used. Illustrations of how the package has been employed are given along with instructions for its utilisation. Program summaryProgram title: Plato Catalogue identifier: AEFC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFC_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 219 974 No. of bytes in distributed program, including test data, etc.: 1 821 493 Distribution format: tar.gz Programming language: C/MPI and PERL Computer: Apple Macintosh, PC, Unix machines Operating system: Unix, Linux and Mac OS X Has the code been vectorised or parallelised?: Yes, up to 256 processors tested RAM: Up to 2 Gbytes per processor Classification: 7.3 External routines: LAPACK, BLAS and optionally ScaLAPACK, BLACS, PBLAS, FFTW Nature of problem: Density functional theory study of electronic structure and total energies of molecules, crystals and surfaces. Solution method: Localised orbital based density functional theory. Restrictions: Tight-binding and density functional theory only, no exact exchange. Unusual features: Both atom centred and uniform meshes available

RS-34 (Peacekeeper Post Boost Propulsion System) Orbital Debris Application Concept Study

Science.gov (United States)

Esther, Elizabeth A.; Burnside, Christopher G.

2013-01-01

The Advanced Concepts Office (ACO) at the NASA Marshall Space Flight Center (MSFC) lead a study to evaluate the Rocketdyne produced RS-34 propulsion system as it applies to an orbital debris removal design reference mission. The existing RS-34 propulsion system is a remaining asset from the de-commissioned United States Air Force Peacekeeper ICBM program; specifically the pressure-fed storable bi-propellant Stage IV Post Boost Propulsion System. MSFC gained experience with the RS-34 propulsion system on the successful Ares I-X flight test program flown in the Ares I-X Roll control system (RoCS). The heritage hardware proved extremely robust and reliable and sparked interest for further utilization on other potential in-space applications. Subsequently, MSFC is working closely with the USAF to obtain all the remaining RS-34 stages for re-use opportunities. Prior to pursuit of securing the hardware, MSFC commissioned the Advanced Concepts Office to understand the capability and potential applications for the RS-34 Phoenix stage as it benefits NASA, DoD, and commercial industry. Originally designed, the RS-34 Phoenix provided in-space six-degrees-of freedom operational maneuvering to deploy multiple payloads at various orbital locations. The RS-34 Concept Study, preceded by a utilization study to understand how the unique capabilities of the RS-34 Phoenix and its application to six candidate missions, sought to further understand application for an orbital debris design reference mission as the orbital debris removal mission was found to closely mimic the heritage RS-34 mission. The RS-34 Orbital Debris Application Concept Study sought to identify multiple configurations varying the degree of modification to trade for dry mass optimization and propellant load for overall capability and evaluation of several candidate missions. The results of the RS-34 Phoenix Utilization Study show that the system is technically sufficient to successfully support all of the missions

Analysis of Hansen's Inferior and Superior Partial Anomalies and the Division of the Elliptic Orbit into Two Segments

Science.gov (United States)

Sharaf, M. A.; Saad, A. S.

2017-10-01

In this paper, a novel analysis was established to prove how Hansen's inferior and superior partial anomalies k and k_1 can divide the elliptic orbit into two segments. The analysis depends on the departures of r (for k) and 1/r (for k1) from their minima. By these departures, we can find: (i) Transformations relating the eccentric anomaly to k and the true anomaly to k1. (ii) Expressions for k and k_1 in terms of the orbital elements. (iii) The interpretation and the intervals of definition of two moduli (X, S) related to k and k_1. (iv) The extreme values of r and the elliptic equations in terms of k and k1. (v) For r' and r'', the modulus X as a measure of the asymmetry of r' (or r'') from r'' (or r'), and the modulus S12 as a measure of the asymmetry of r' and r'' from the minimum value of r. (vi) A description of the segments represented by k and k1. (vii) The relative position of the radius vector at k0° and k1=180°.

Neonatal orbital abscess

Directory of Open Access Journals (Sweden)

Khalil M Al-Salem

2014-01-01

Full Text Available Orbital complications due to ethmoiditis are rare in neonates. A case of orbital abscess due to acute ethmoiditis in a 28-day-old girl is presented. A Successful outcome was achieved following antimicrobial therapy alone; spontaneous drainage of the abscess occurred from the lower lid without the need for surgery. From this case report, we intend to emphasize on eyelid retraction as a sign of neonatal orbital abscess, and to review all the available literature of similar cases.

Optimizing Orbit-Instrument Configuration for Global Precipitation Mission (GPM) Satellite Fleet

Science.gov (United States)

Smith, Eric A.; Adams, James; Baptista, Pedro; Haddad, Ziad; Iguchi, Toshio; Im, Eastwood; Kummerow, Christian; Einaudi, Franco (Technical Monitor)

2001-01-01

Following the scientific success of the Tropical Rainfall Measuring Mission (TRMM) spearheaded by a group of NASA and NASDA scientists, their external scientific collaborators, and additional investigators within the European Union's TRMM Research Program (EUROTRMM), there has been substantial progress towards the development of a new internationally organized, global scale, and satellite-based precipitation measuring mission. The highlights of this newly developing mission are a greatly expanded scope of measuring capability and a more diversified set of science objectives. The mission is called the Global Precipitation Mission (GPM). Notionally, GPM will be a constellation-type mission involving a fleet of nine satellites. In this fleet, one member is referred to as the "core" spacecraft flown in an approximately 70 degree inclined non-sun-synchronous orbit, somewhat similar to TRMM in that it carries both a multi-channel polarized passive microwave radiometer (PMW) and a radar system, but in this case it will be a dual frequency Ku-Ka band radar system enabling explicit measurements of microphysical DSD properties. The remainder of fleet members are eight orbit-synchronized, sun-synchronous "constellation" spacecraft each carrying some type of multi-channel PMW radiometer, enabling no worse than 3-hour diurnal sampling over the entire globe. In this configuration the "core" spacecraft serves as a high quality reference platform for training and calibrating the PMW rain retrieval algorithms used with the "constellation" radiometers. Within NASA, GPM has advanced to the pre-formulation phase which has enabled the initiation of a set of science and technology studies which will help lead to the final mission design some time in the 2003 period. This presentation first provides an overview of the notional GPM program and mission design, including its organizational and programmatic concepts, scientific agenda, expected instrument package, and basic flight

Program Analysis Scenarios in Rascal

NARCIS (Netherlands)

M.A. Hills (Mark); P. Klint (Paul); J.J. Vinju (Jurgen); F. Durán

2012-01-01

textabstractRascal is a meta programming language focused on the implementation of domain-specific languages and on the rapid construction of tools for software analysis and software transformation. In this paper we focus on the use of Rascal for software analysis. We illustrate a range of scenarios

Analysis of orbitally excited B-mesons

CERN Document Server

Albrecht, Zoltan; Quast, Gunter

2003-01-01

This thesis reports on the study of orbitally excited B** mesons in DELPHI b-events taken in the years 1994 to 2000 with the DELPHI detector at the LEP collider. The analyses presented represent the result of applying much improved and extended techniques of spectroscopy since the first DELPHI publication in 1995. A major improvement has occurred in the area of particle identification, where a neural network approach has been implemented in the DELPHI software package. Developments in the area of neural networks have led to much improved enrichment of the excited B states. The Bˆ{**} neural networks identify, on a track-by-track basis, the decay pion/kaon originating from the Bˆ{**} decay, suppressing background and keeping signal events in an efficient way. To improve detector resolution, a further application of neural networks has been applied to reconstruct the underlying Q-value. The corresponding network gives a correction on existing measurements of the Q-value in the form of a probability density fu...

Preliminary Products of Precise Orbit Determination Using Satellite Laser Ranging Observations for ILRS AAC

Directory of Open Access Journals (Sweden)

Young-Rok Kim

2012-09-01

Full Text Available In this study, we present preliminary results of precise orbit determination (POD using satellite laser ranging (SLR observations for International Laser Ranging Service (ILRS Associate Analysis Center (AAC. Using SLR normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2, the NASA/GSFC GEODYN II software are utilized for POD. Weekly-based orbit determination strategy is applied to process SLR observations and the post-fit residuals check, and external orbit comparison are performed for orbit accuracy assessment. The root mean square (RMS value of differences between observations and computations after final iteration of estimation process is used for post-fit residuals check. The result of ILRS consolidated prediction format (CPF is used for external orbit comparison. Additionally, we performed the precision analysis of each ILRS station by post-fit residuals. The post-fit residuals results show that the precisions of the orbits of LAGEOS-1 and LAGEOS-2 are 0.9 and 1.3 cm, and those of ETALON-1 and ETALON-2 are 2.5 and 1.9 cm, respectively. The orbit assessment results by ILRS CPF show that the radial accuracies of LAGEOS-1 and LAGEOS-2 are 4.0 cm and 5.3 cm, and the radial accuracies of ETALON-1 and ETALON-2 are 30.7 cm and 7.2 cm. These results of station precision analysis confirm that the result of this study is reasonable to have implications as preliminary results for administrating ILRS AAC.

Characteristics of persistent spin current components in a quasi-periodic Fibonacci ring with spin–orbit interactions: Prediction of spin–orbit coupling and on-site energy

International Nuclear Information System (INIS)

Patra, Moumita; Maiti, Santanu K.

2016-01-01

In the present work we investigate the behavior of all three components of persistent spin current in a quasi-periodic Fibonacci ring subjected to Rashba and Dresselhaus spin–orbit interactions. Analogous to persistent charge current in a conducting ring where electrons gain a Berry phase in presence of magnetic flux, spin Berry phase is associated during the motion of electrons in presence of a spin–orbit field which is responsible for the generation of spin current. The interplay between two spin–orbit fields along with quasi-periodic Fibonacci sequence on persistent spin current is described elaborately, and from our analysis, we can estimate the strength of any one of two spin–orbit couplings together with on-site energy, provided the other is known. - Highlights: • Determination of Rashba and Dresselhaus spin–orbit fields is discussed. • Characteristics of all three components of spin current are explored. • Possibility of estimating on-site energy is given. • Results can be generalized to any lattice models.

Characteristics of persistent spin current components in a quasi-periodic Fibonacci ring with spin–orbit interactions: Prediction of spin–orbit coupling and on-site energy

Energy Technology Data Exchange (ETDEWEB)

Patra, Moumita; Maiti, Santanu K., E-mail: santanu.maiti@isical.ac.in

2016-12-15

In the present work we investigate the behavior of all three components of persistent spin current in a quasi-periodic Fibonacci ring subjected to Rashba and Dresselhaus spin–orbit interactions. Analogous to persistent charge current in a conducting ring where electrons gain a Berry phase in presence of magnetic flux, spin Berry phase is associated during the motion of electrons in presence of a spin–orbit field which is responsible for the generation of spin current. The interplay between two spin–orbit fields along with quasi-periodic Fibonacci sequence on persistent spin current is described elaborately, and from our analysis, we can estimate the strength of any one of two spin–orbit couplings together with on-site energy, provided the other is known. - Highlights: • Determination of Rashba and Dresselhaus spin–orbit fields is discussed. • Characteristics of all three components of spin current are explored. • Possibility of estimating on-site energy is given. • Results can be generalized to any lattice models.

Seawifs Technical Report Series. Volume 2: Analysis of Orbit Selection for Seawifs: Ascending Versus Descending Node

Science.gov (United States)

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

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

Science.gov (United States)

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.

MOM-E: Moon-Orbiting Mothership Explorer

Science.gov (United States)

Murphy, Gloria A.

2010-01-01

The National Aeronautics and Space Administration proposed that a new class of robotic space missions and spacecrafts be introduced to "ensure that future missions are safe, sustainable and affordable". Indeed, the United States space program aims for a return to manned space missions beyond Earth orbit, and robotic explorers are intended to pave the way. This vision requires that all future missions become less costly, provide a sustainable business plan, and increase in safety. Over the course of several fast feasibility studies that considered the 3 drivers above, the small-scale, consumer-driven Moon-Orbiting Mothership Explorer (MOM-E) mission was born. MOM-E's goals are to enable space exploration by offering a scaled down platform which carries multiple small space explorers to the Moon. Each payload will be dropped at their desired destination, offering a competitive price to customers. MOM-E's current scope of operations is limited to the Moon and will be used as a proof of concept mission. However, MOM-E is specifically designed with the idea that the platform is scalable.

The Trailblazer Program

Science.gov (United States)

Trefney, Charles J.

1999-01-01

This paper presents the "Three Pillars of Success" for the Trailblazer Program. The topics include: 1) The "Rocket Equation" for SSTO (Single Stage To Orbit); 2) The Rocket I* Barrier; 3) Rocket-Based Combined-Cycle Engine; 4) Potential for Reusability; 5) Factors Mitigating RBCC Performance; 6) The "Trailblazer" Program; 7) Trailblazer Performance Goals; 8) Trailblazer Reference Vehicle; and 9) Trailblazer Program Architecture.

Air-ground temperature coupling: analysis by means of Thermal Orbits

Czech Academy of Sciences Publication Activity Database

Čermák, Vladimír; Bodri, L.

2016-01-01

Roč. 6, č. 1 (2016), s. 112-122 ISSN 2160-0414 R&D Projects: GA ČR(CZ) GAP210/11/0183; GA MŠk(CZ) LG13040 Institutional support: RVO:67985530 Keywords : Thermal Orbits * temperature monitoring * air temperature vs ground temperature Subject RIV: DG - Athmosphere Sciences, Meteorology

Matlab programming for numerical analysis

CERN Document Server

Lopez, Cesar

2014-01-01

MATLAB is a high-level language and environment for numerical computation, visualization, and programming. Using MATLAB, you can analyze data, develop algorithms, and create models and applications. The language, tools, and built-in math functions enable you to explore multiple approaches and reach a solution faster than with spreadsheets or traditional programming languages, such as C/C++ or Java. Programming MATLAB for Numerical Analysis introduces you to the MATLAB language with practical hands-on instructions and results, allowing you to quickly achieve your goals. You will first become

Development, Demonstration and Validation of the Deep Space Orbit Determination Software Using Lunar Prospector Tracking Data

Directory of Open Access Journals (Sweden)

Eunji Lee

2017-09-01

Full Text Available The deep space orbit determination software (DSODS is a part of a flight dynamic subsystem (FDS for the Korean Pathfinder Lunar Orbiter (KPLO, a lunar exploration mission expected to launch after 2018. The DSODS consists of several sub modules, of which the orbit determination (OD module employs a weighted least squares algorithm for estimating the parameters related to the motion and the tracking system of the spacecraft, and subroutines for performance improvement and detailed analysis of the orbit solution. In this research, DSODS is demonstrated and validated at lunar orbit at an altitude of 100 km using actual Lunar Prospector tracking data. A set of a priori states are generated, and the robustness of DSODS to the a priori error is confirmed by the NASA planetary data system (PDS orbit solutions. Furthermore, the accuracy of the orbit solutions is determined by solution comparison and overlap analysis as about tens of meters. Through these analyses, the ability of the DSODS to provide proper orbit solutions for the KPLO are proved.

Update on orbital reconstruction.

Science.gov (United States)

Chen, Chien-Tzung; Chen, Yu-Ray

2010-08-01

Orbital trauma is common and frequently complicated by ocular injuries. The recent literature on orbital fracture is analyzed with emphasis on epidemiological data assessment, surgical timing, method of approach and reconstruction materials. Computed tomographic (CT) scan has become a routine evaluation tool for orbital trauma, and mobile CT can be applied intraoperatively if necessary. Concomitant serious ocular injury should be carefully evaluated preoperatively. Patients presenting with nonresolving oculocardiac reflex, 'white-eyed' blowout fracture, or diplopia with a positive forced duction test and CT evidence of orbital tissue entrapment require early surgical repair. Otherwise, enophthalmos can be corrected by late surgery with a similar outcome to early surgery. The use of an endoscope-assisted approach for orbital reconstruction continues to grow, offering an alternative method. Advances in alloplastic materials have improved surgical outcome and shortened operating time. In this review of modern orbital reconstruction, several controversial issues such as surgical indication, surgical timing, method of approach and choice of reconstruction material are discussed. Preoperative fine-cut CT image and thorough ophthalmologic examination are key elements to determine surgical indications. The choice of surgical approach and reconstruction materials much depends on the surgeon's experience and the reconstruction area. Prefabricated alloplastic implants together with image software and stereolithographic models are significant advances that help to more accurately reconstruct the traumatized orbit. The recent evolution of orbit reconstruction improves functional and aesthetic results and minimizes surgical complications.

Energy Decomposition Analysis Based on Absolutely Localized Molecular Orbitals for Large-Scale Density Functional Theory Calculations in Drug Design.

Science.gov (United States)

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.

Satellite laser ranging to low Earth orbiters: orbit and network validation

Science.gov (United States)

Arnold, Daniel; Montenbruck, Oliver; Hackel, Stefan; Sośnica, Krzysztof

2018-04-01

Satellite laser ranging (SLR) to low Earth orbiters (LEOs) provides optical distance measurements with mm-to-cm-level precision. SLR residuals, i.e., differences between measured and modeled ranges, serve as a common figure of merit for the quality assessment of orbits derived by radiometric tracking techniques. We discuss relevant processing standards for the modeling of SLR observations and highlight the importance of line-of-sight-dependent range corrections for the various types of laser retroreflector arrays. A 1-3 cm consistency of SLR observations and GPS-based precise orbits is demonstrated for a wide range of past and present LEO missions supported by the International Laser Ranging Service (ILRS). A parameter estimation approach is presented to investigate systematic orbit errors and it is shown that SLR validation of LEO satellites is not only able to detect radial but also along-track and cross-track offsets. SLR residual statistics clearly depend on the employed precise orbit determination technique (kinematic vs. reduced-dynamic, float vs. fixed ambiguities) but also reveal pronounced differences in the ILRS station performance. Using the residual-based parameter estimation approach, corrections to ILRS station coordinates, range biases, and timing offsets are derived. As a result, root-mean-square residuals of 5-10 mm have been achieved over a 1-year data arc in 2016 using observations from a subset of high-performance stations and ambiguity-fixed orbits of four LEO missions. As a final contribution, we demonstrate that SLR can not only validate single-satellite orbit solutions but also precise baseline solutions of formation flying missions such as GRACE, TanDEM-X, and Swarm.

Supervoltage orbital radiotherapy for progressive Graves' ophthalmopathy

International Nuclear Information System (INIS)

Kriss, J.P.; McDougall, I.R.; Petersen, I.A.; Donaldson, S.S.

1989-01-01

Since 1968 we have employed supervoltage orbital radiation as treatment for severe progressive Graves' ophthalmopathy. A numerical ophthalmic index was used to asess pre- and post-treatment serverity. In the past 20 years we have treated 311 patients of whom 275 have been followed for ≤ 1 year or until any eye surgery was performed. An orbital radiation dosage of 2000 rads in 2 weeks was used for the majority of patients (Series I and III). Series II patients received an orbital dose of 3000 rads in 3 weeks. Demographic differences were observed between these series, thus mandating presentation of the results of each separately. Analyses excluded any result achieved by any post-radiation surgical procedure on the eyes. Post-theraphy worsening of ophtalmopathy occurred in only 29 of 1025 observations. Improvement or complete resolution was observed within each category of eye involvement, but lack of favorable response was also recorded in significant numbers. Improvement in proptosis occurred with the lowest frequency and magnitude. About 30% of the patients required eye muscle surgery to correct residual diplopia. Analysis of the data by step-wise linear regression analysis enabled us a. to derive formulae predicting the problable response to radiation therapy according to sign and severity, and b. identify parameters which diminished the likelihood or the extent of a favorable response. The latter included male sex, never thyrotoxic, age greater than 60 years, and requirement for concomitant treatment for hyperthyroidism. No long-term adverse reactions attributable to the radiotherapy have been observed. We conclude that supervoltage orbital radiotherapy, combined with later eye muscle surgery if necessary, is an effective treatment strategy for progressive Graves' ophthalmopathy. (author)

Orbital glass in HTSC

International Nuclear Information System (INIS)

Kusmartsev, F.V.

1992-10-01

The physical reasons why the orbital glass may exist in granular high-temperature superconductors and the existing experimental data appeared recently are discussed. The orbital glass is characterized by the coexistence of the orbital paramagnetic state with the superconducting state and occurs at small magnetic fields H c0 c1 . The transition in orbital glass arises at the critical field H c0 which is inversely proportional to the surface cross-area S of an average grain. In connection with theoretical predictions the possible experiments are proposed. (author). 10 refs

Invariant Solar Sail Formations in Elliptical Sun-Synchronous Orbits

Science.gov (United States)

Parsay, Khashayar

. These averaged rates are used to analytically derive the necessary conditions for a drift-free solar sail formation in Sun-synchronous orbits, assuming a fixed Sun-pointing orientation for each sail in formation. Next, the problem of formation design is solved using nonlinear programming for optimal two-craft, three-craft, and four-craft solar sail formations, in terms of formation quality and stability. Finally, the problem of formation establishment is addressed using optimal control theory, assuming that the sails are capable of making small changes to their orientations with respect to the Sun. These studies demonstrate the feasibility of solar sail formation flying for exploring the geomagnetic tail and improve upon previous work, which only considered unnatural relative motions that require continuous use of active control to remain in formation.

The Mars Reconnaissance Orbiter Mission: 10 Years of Exploration from Mars Orbit

Science.gov (United States)

Johnston, M. Daniel; Zurek, Richard W.

2016-01-01

The Mars Reconnaissance Orbiter ( MRO ) entered Mars orbit on March 10, 2006. After five months of aerobraking, a series of propulsive maneuvers were used to establish the desired low -altitude science orbit. The spacecraft has been on station in its 255 x 320 k m, sun -synchronous (approximately 3 am -pm ), primary science orbit since September 2006 performing both scientific and Mars programmatic support functions. This paper will provide a summary of the major achievements of the mission to date and the major flight activities planned for the remainder of its third Extended Mission (EM3). Some of the major flight challenges the flight team has faced are also discussed.

Seismic analysis program group: SSAP

International Nuclear Information System (INIS)

Uchida, Masaaki

2002-05-01

A group of programs SSAP has been developed, each member of which performs seismic calculation using simple single-mass system model or multi-mass system model. For response of structures to a transverse s-wave, a single-mass model program calculating response spectrum and a multi-mass model program are available. They perform calculation using the output of another program, which produces simulated earthquakes having the so-called Ohsaki-spectrum characteristic. Another program has been added, which calculates the response of one-dimensional multi-mass systems to vertical p-wave input. It places particular emphasis on the analysis of the phenomena observed at some shallow earthquakes in which stones jump off the ground. Through a series of test calculations using these programs, some interesting information has been derived concerning the validity of superimposing single-mass model calculation, and also the condition for stones to jump. (author)

Orbital Infarction due to Sickle Cell Disease without Orbital Pain

Directory of Open Access Journals (Sweden)

Cameron L. McBride

2016-01-01

Full Text Available Sickle cell disease is a hemoglobinopathy that results in paroxysmal arteriolar occlusion and tissue infarction that can manifest in a plurality of tissues. Rarely, these infarcted crises manifest in the bony orbit. Orbital infarction usually presents with acute onset of periorbital tenderness, swelling, erythema, and pain. Soft tissue swelling can result in proptosis and attenuation of extraocular movements. Expedient diagnosis of sickle cell orbital infarction is crucial because this is a potentially sight-threatening entity. Diagnosis can be delayed since the presentation has physical and radiographic findings mimicking various infectious and traumatic processes. We describe a patient who presented with sickle cell orbital crisis without pain. This case highlights the importance of maintaining a high index of suspicion in patients with known sickle cell disease or of African descent born outside the United States in a region where screening for hemoglobinopathy is not routine, even when the presentation is not classic.

Eye and orbital cavity

International Nuclear Information System (INIS)

Panfilova, G.V.; Koval', G.Yu.

1984-01-01

Radioanatomy of eyes and orbit is described. Diseases of the orbit (developmental anomalies, inflammatory diseases, lacrimal apparatus deseases, toxoplasmosis, tumors and cysts et al.), methods of foreign body localization in the eye are considered. Roentgenograms of the orbit and calculation table for foreign body localization in spherical eyes of dissimilar diameter are presented

A UNIFIED FRAMEWORK FOR THE ORBITAL STRUCTURE OF BARS AND TRIAXIAL ELLIPSOIDS

Energy Technology Data Exchange (ETDEWEB)

Valluri, Monica; Abbott, Caleb [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Shen, Juntai [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Debattista, Victor P., E-mail: mvalluri@umich.edu, E-mail: calebga@umich.edu, E-mail: jshen@shao.ac.cn, E-mail: vpdebattista@uclan.ac.uk [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE (United Kingdom)

2016-02-20

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.

Numerical evaluation of two-center integrals over Slater type orbitals

Energy Technology Data Exchange (ETDEWEB)

Kurt, S. A., E-mail: slaykurt@gmail.com [Department of Physics, Natural Sciences Institute, Ondokuz Mayıs University, 55139, Samsun (Turkey); Yükçü, N., E-mail: nyukcu@gmail.com [Department of Energy Systems Engineering, Faculty of Technology, Adıyaman University, 02040, Adıyaman (Turkey)

2016-03-25

Slater Type Orbitals (STOs) which one of the types of exponential type orbitals (ETOs) are used usually as basis functions in the multicenter molecular integrals to better understand physical and chemical properties of matter. In this work, we develop algorithms for two-center overlap and two-center two-electron hybrid and Coulomb integrals which are calculated with help of translation method for STOs and some auxiliary functions by V. Magnasco’s group. We use Mathematica programming language to produce algorithms for these calculations. Numerical results for some quantum numbers are presented in the tables. Consequently, we compare our obtained numerical results with the other known literature results and other details of evaluation method are discussed.

Numerical evaluation of two-center integrals over Slater type orbitals

International Nuclear Information System (INIS)

Kurt, S. A.; Yükçü, N.

2016-01-01

Slater Type Orbitals (STOs) which one of the types of exponential type orbitals (ETOs) are used usually as basis functions in the multicenter molecular integrals to better understand physical and chemical properties of matter. In this work, we develop algorithms for two-center overlap and two-center two-electron hybrid and Coulomb integrals which are calculated with help of translation method for STOs and some auxiliary functions by V. Magnasco’s group. We use Mathematica programming language to produce algorithms for these calculations. Numerical results for some quantum numbers are presented in the tables. Consequently, we compare our obtained numerical results with the other known literature results and other details of evaluation method are discussed.

Local orbit feedback

International Nuclear Information System (INIS)

Anon.

1991-01-01

Critically aligned experiments are sensitive to small changes in the electron beam orbit. At the NSLS storage rings, the electron beam and photon beam motions have been monitored over the past several years. In the survey conducted in 1986 by the NSLS Users Executive Committee, experimenters requested the vertical beam position variation and the vertical angle variation, within a given fill, remain within 10 μm and 10 μr, respectively. This requires improvement in the beam stability by about one order of magnitude. At the NSLS and SSRL storage rings, the beam that is originally centered on the position monitor by a dc orbit correction is observed to have two kinds of motion: a dc drift over a storage period of several hours and a beam bounce about its nominal position. These motions are a result of the equilibrium orbit not being held perfectly stable due to time-varying errors introduced into the magnetic guide field by power supplies, mechanical vibration of the magnets, cooling water temperature variations, etc. The approach to orbit stabilization includes (1) identifying and suppressing as many noise sources on the machine as possible, (2) correcting the beam position globally (see Section 6) by controlling a number of correctors around the circumference of the machine, and (3) correcting the beam position and angle at a given source location by position feedback using local detectors and local orbit bumps. The third approach, called Local Orbit Feedback will be discussed in this section

ORBIT II sub-analysis: Impact of impaired renal function following treatment of severely calcified coronary lesions with the Orbital Atherectomy System.

Science.gov (United States)

Lee, Michael S; Lee, Arthur C; Shlofmitz, Richard A; Martinsen, Brad J; Hargus, Nick J; Elder, Mahir D; Généreux, Philippe; Chambers, Jeffrey W

2017-04-01

To investigate the safety and efficacy of the coronary Orbital Atherectomy System (OAS) to prepare severely calcified lesions for stent deployment in patients grouped by renal function. Percutaneous coronary intervention (PCI) of severely calcified lesions is associated with increased rates of major adverse cardiac events (MACE), including death, myocardial infarction (MI), and target vessel revascularization (TVR) compared with PCI of non-calcified vessels. Patients with chronic kidney disease (CKD) are at increased risk for MACE after PCI. The impact of CKD on coronary orbital atherectomy treatment has not been well characterized. ORBIT II was a prospective, multicenter trial in the U.S., which enrolled 443 patients with severely calcified coronary lesions. The MACE rate was defined as a composite of cardiac death, MI, and target vessel revascularization. Of the 441 patients enrolled with known estimated glomerular filtration rate (eGFR) values at baseline, 333 (75.5%) patients had eGFR renal impairment had a higher MACE rate through one year follow-up due to a higher rate of periprocedural MI. Interestingly, the rates of cardiac death and revascularization through 1-year were similar in patients with eGFR renal impairment and severely calcified coronary lesions. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.