WorldWideScience

Sample records for supersynchronous transfer orbit

  1. Negating the Yearly Eccentricity Magnitude Variation of Super-synchronous Disposal Orbits due to Solar Radiation Pressure

    Science.gov (United States)

    Jones, S. L.

    Solar radiation pressure alters satellites' eccentricity by accelerating and decelerating them during each orbit. The accumulated perturbation cancels yearly for geostationary satellites, but meanwhile the perigee radius changes. Disposed satellites must be reorbited higher to compensate, using more fuel. The examined disposal orbit points toward the Sun and uses the satellite's natural eccentricity. This causes the eccentricity vector to only change direction, keeping the perigee radius constant. This thesis verifies this behavior over one year with an analytical derivation and MATLAB simulation, gaining useful insights into its cause. The traditional and proposed disposal orbits are then modeled using NASA's GMAT for more realistic simulations. The proposed orbit's sensitivity to satellite and initialization errors is also examined. Relationships are developed to show these errors' effect on the perigee radius. In conclusion, while this orbit can be used in the short term, margins are necessary to guarantee protection of the geostationary belt.

  2. Optimization adn Guidance of Very Low-Thrust Transfers to Geostatoinary Orbit

    Science.gov (United States)

    Gil-Fernandez, J.; Tarabini, L.; Graziano, M.; Gomez-Tierno, M. A.

    A new hybrid direct-indirect optimization algorithm is presented to compute the minimum-time transfer between two orbits, including the phasing with a desired spacecraft. Very-low thrust means several hundred revolutions to perform the large change in orbital elements. The optimal control solution of the fast-evolution problem combined with a direct method for the secular trajectory avoids the numerical instability arising in very long propagations, decreases the computational time, reduces the sensitivity to the initial guess and provides a feasible transfer at every optimization step. Optimization of transfers from GTO to GEO is presented and two types of trajectories are analysed, sub-synchronous (apogee constrained below GEO altitude) and super-synchronous (free apogee altitude). The optimization of a transfer from LEO to a very high orbit (11 x 23 RE) is presented, showing the applicability of the method to different problems. A guidance algorithm is presented to compensate the deviations of the real trajectory from the optimal one due to off-nominal conditions. The results in closed-loop simulation of the guidance scheme to compensate deterministic perturbations not considered in the optimization show good performances in both analysed missions.

  3. Sub- and Super-Synchronous Self-Excited Vibrations of a Columnar Rotor Due to Axial Clearance Flow

    Science.gov (United States)

    Nishimura, H.; Horiguchi, H.; Suzuki, T.; Sugiyama, K.; Tsujimoto, Y.

    2016-11-01

    Sub- and super-synchronous self-excited vibrations due to axial clearance flows were observed in a columnar rotor with an upstream seal in experiments. A smaller clearance on the downstream seal had a larger effect of stabilizing the rotor. In computations, it was found that the rotordynamic fluid force tangential to the whirling orbit, which is caused as a response to the vibrations (whirling motions), destabilizes the rotor in the case of the upstream seal and stabilizes the rotor in the case of the downstream seal. It was clarified in the 1-D flow model that the tangential rotordynamic fluid force is mainly caused by an inertia of the clearance flow.

  4. The Subscale Orbital Fluid Transfer Experiment

    Science.gov (United States)

    Meserole, J. S.; Collins, Frank G.; Jones, Ogden; Antar, Basil; Menzel, Reinhard; Gray, Perry

    1989-01-01

    The Center for Advanced Spacecraft Propulsion (CASP) is a subcontractor to Boeing Aerospace Corporation to provide support for the concept definition and design of a subscale orbital fluid transfer experiment (SOFTE). SOFTE is an experiment that will look at the fluid mechanics of the process of transfer of a saturated fluid between two tanks. The experiment will be placed in two get away special (GAS) can containers; the tanks will be in one container and the power and electronics will be in a second container. Since GAS cans are being used, the experiment will be autonomous. The work during the present year consisted of examining concepts for visual observation of the fluid transfer process, methods for accurately metering the amount of fluid transferred between the two tanks, possible test fluids, and materials for the elastomeric diaphragm.

  5. United States orbital transfer vehicle programs

    Science.gov (United States)

    Gunn, Charles R.

    The United States will rely on five orbital transfer vehicles to carry spacecraft to higher energy orbits than achievable by the Space Shuttle or various Expendable Launch Vehicles (ELV). These vehicles are the Payload Assist Module-Delta (PAM-D), an upgraded version designated PAM-DII, the Inertial Upper Stage (IUS), the Transfer Orbit Stage (TOS), and the Orbital Maneuvering Vehicle (OMV). Development of these vehicles have evolved through contrasting cultures of government and commercial management. The spectrum of their capabilities range from providing spacecraft with only a preprogrammed perigee velocity additions to man-in-the-loop remote controlled spacecraft rendezvous, docking, retrieval and return to a space base; either the Shuttle or the Space Station Freedom. The PAM-D, PAM-DII, and IUS are now nearing maturity. Their characteristics, flight record, costs, and projected future uses are defined. The TOS and OMV are currently in development with first uses scheduled in 1992 and 1993, respectively. The TOS is being commercially developed while the OMV is government developed. The TOS and OMV capabilities, constraints, and costs are reviewed.

  6. 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.

  7. Transfer orbit stage mechanisms thermal vacuum test

    Science.gov (United States)

    Oleary, Scott T.

    1990-01-01

    A systems level mechanisms test was conducted on the Orbital Sciences Corp.'s Transfer Orbit Stage (TOS). The TOS is a unique partially reusable transfer vehicle which will boost a satellite into its operational orbit from the Space Shuttle's cargo bay. The mechanical cradle and tilt assemblies will return to earth with the Space Shuttle while the Solid Rocket Motor (SRM) and avionics package are expended. A mechanisms test was performed on the forward cradle and aft tilting assemblies of the TOS under thermal vacuum conditions. Actuating these assemblies under a 1 g environment and thermal vacuum conditions proved to be a complex task. Pneumatic test fixturing was used to lift the forward cradle, and tilt the SRM, and avionics package. Clinometers, linear voltage displacement transducers, and load cells were used in the thermal vacuum chamber to measure the performance and characteristics of the TOS mechanism assembly. Incorporation of the instrumentation and pneumatic system into the test setup was not routine since pneumatic actuation of flight hardware had not been previously performed in the facility. The methods used are presented along with the problems experienced during the design, setup and test phases.

  8. Computational chemistry and aeroassisted orbital transfer vehicles

    Science.gov (United States)

    Cooper, D. M.; Jaffe, R. L.; Arnold, J. O.

    1985-01-01

    An analysis of the radiative heating phenomena encountered during a typical aeroassisted orbital transfer vehicle (AOTV) trajectory was made to determine the potential impact of computational chemistry on AOTV design technology. Both equilibrium and nonequilibrium radiation mechanisms were considered. This analysis showed that computational chemistry can be used to predict (1) radiative intensity factors and spectroscopic data; (2) the excitation rates of both atoms and molecules; (3) high-temperature reaction rate constants for metathesis and charge exchange reactions; (4) particle ionization and neutralization rates and cross sections; and (5) spectral line widths.

  9. Hubble Space Telescope On-orbit Transfer Function Test

    Science.gov (United States)

    Vadlamudi, N.; Blair, M. A.; Clapp, B. R.

    1992-01-01

    The paper describes the On-orbit Transfer Function Test (TFT) designed for on-orbit vibration testing of the Hubble Space Telescope (HST). The TFT provides means for extracting accurate on-orbit characteristics of HST flexible body dynamics, making it possible to check periodically the state of the vehicle on-orbit and to assess changes in modal parameters.

  10. Orbital Transfer Techniques for Round-Trip Mars Missions

    Science.gov (United States)

    Landau, Damon

    2013-01-01

    The human exploration of Phobos and Deimos or the retrieval of a surface sample launched to low-Mars orbit presents a highly constrained orbital transfer problem. In general, the plane of the target orbit will not be accessible from the arrival or departure interplanetary trajectories with an (energetically optimal) tangential burn at periapsis. The orbital design is further complicated by the addition of a high-energy parking orbit for the relatively massive Deep Space Vehicle to reduce propellant expenditure, while the crew transfers to and from the target orbit in a smaller Space Exploration Vehicle. The proposed strategy shifts the arrival and departure maneuvers away from periapsis so that the apsidal line of the parking orbit lies in the plane of the target orbit, permitting highly efficient plane change maneuvers at apoapsis of the elliptical parking orbit. An apsidal shift during the arrival or departure maneuver is approximately five times as efficient as maneuvering while in Mars orbit, thus significantly reducing the propellant necessary to transfer between the arrival, target, and departure orbits.

  11. Orbital Transfer Techniques for Round-Trip Mars Missions

    Science.gov (United States)

    Landau, Damon

    2013-01-01

    The human exploration of Phobos and Deimos or the retrieval of a surface sample launched to low-Mars orbit presents a highly constrained orbital transfer problem. In general, the plane of the target orbit will not be accessible from the arrival or departure interplanetary trajectories with an (energetically optimal) tangential burn at periapsis. The orbital design is further complicated by the addition of a high-energy parking orbit for the relatively massive Deep Space Vehicle to reduce propellant expenditure, while the crew transfers to and from the target orbit in a smaller Space Exploration Vehicle. The proposed strategy shifts the arrival and departure maneuvers away from periapsis so that the apsidal line of the parking orbit lies in the plane of the target orbit, permitting highly efficient plane change maneuvers at apoapsis of the elliptical parking orbit. An apsidal shift during the arrival or departure maneuver is approximately five times as efficient as maneuvering while in Mars orbit, thus significantly reducing the propellant necessary to transfer between the arrival, target, and departure orbits.

  12. Study of the transfer between libration point orbits and lunar orbits in Earth-Moon system

    Science.gov (United States)

    Cheng, Yu; Gómez, Gerard; Masdemont, Josep J.; Yuan, Jianping

    2017-02-01

    This paper is devoted to the study of the transfer problem from a libration point orbit of the Earth-Moon system to an orbit around the Moon. The transfer procedure analysed has two legs: the first one is an orbit of the unstable manifold of the libration orbit and the second one is a transfer orbit between a certain point on the manifold and the final lunar orbit. There are only two manoeuvres involved in the method and they are applied at the beginning and at the end of the second leg. Although the numerical results given in this paper correspond to transfers between halo orbits around the L_1 point (of several amplitudes) and lunar polar orbits with altitudes varying between 100 and 500 km, the procedure we develop can be applied to any kind of lunar orbits, libration orbits around the L_1 or L_2 points of the Earth-Moon system, or to other similar cases with different values of the mass ratio.

  13. Dynamical modeling and lifetime analysis of geostationary transfer orbits

    Science.gov (United States)

    Wang, Yue; Gurfil, Pini

    2016-11-01

    The dynamics and lifetime reduction of geostationary transfer orbits (GTOs) are of great importance to space debris mitigation. The orbital dynamics, subjected to a complex interplay of multiple perturbations, are complicated and sensitive to the initial conditions and model parameters. In this paper, a simple but effective non-singular orbital dynamics model in terms of Milankovitch elements is derived. The orbital dynamics, which include the Earth oblateness, luni-solar perturbations, and atmospheric drag, are averaged over the orbital motion of the GTO object, or, as needed, also over the orbital motions of the Moon and Sun, to eliminate the short-period terms. After the averaging process, the effect of the atmospheric drag assumes a simple analytical form. The averaged orbital model is verified through a numerical simulation compared with commercial orbit propagators. GTO lifetime reduction by using the luni-solar perturbations is studied. It is shown that the long-period luni-solar perturbation is induced by the precession of the GTO orbital plane and apsidal line, whereas the short-period perturbation is induced by the periodic luni-solar orbital motions. The long- and short-period perturbations are isolated and studied separately, and their global distribution with respect to the orbital geometry is given. The desired initial orbital geometry with a short orbital lifetime is found and verified by a numerical simulation.

  14. A new method for determination of satellite orbits by transfer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The original idea of a new method for determination of satellite orbits by transfer is from Two-Way Satellite Time and Frequency Transfer (TWSTFT). The original method is called "determination of satellite orbit by transfer". The method is not only for determination of satellite orbit but also for the time transfer with high accuracy and precision. The advantage is that the accuracy and the precision for determination of satellite orbit are very high and the new method is favorable for various applications. The combination of various signals disseminated and received forms various modes of satellite orbit determinations. If receivers at stations receive the own station-disseminated signals via a satellite transponder, it forms an orbit determination mode called "receiving the own station-disseminated signals mode". If receivers at all stations receive the signals disseminated from the master station via satellite transponders, it forms an orbit determination mode called "receiving the master station-disseminated signals mode". If all of receivers at stations receive all stations-disseminated signals via satellite transponders, it forms an orbit determination mode called "receiving all stations-disseminated signals mode". Also there are other combinations of signals for satellite orbit determination. For dif- ferent orbit determination modes with different signal combinations, their rigorous formulae of proc- essing are hereby presented in this paper. The accurate and the precise satellite orbit determination for both of the modes, "receiving the own station-disseminated signals mode" and "receiving the master station-disseminated signals mode" is attempted. It shows that the accuracy and precision for both of modes are nearly the same, the ranging accuracy is better than 1 cm, and the observation residuals of satellite orbit determination are better than 9 cm in the observation duration of 1 day.

  15. A new method for determination of satellite orbits by transfer

    Institute of Scientific and Technical Information of China (English)

    LI ZhiGang; YANG XuHai; AI GuoXiang; SI HuLi; QIAO RongChuan; FENG ChuGang

    2009-01-01

    The original idea of a new method for determination of satellite orbits by transfer is from Two-Way Satellite Time and Frequency Transfer (TWSTFT).The original method is called "determination of satellite orbit by transfer".The method is not only for determination of satellite orbit but also for the time transfer with high accuracy and precision.The advantage is that the accuracy and the precision for determination of satellite orbit are very high and the new method is favorable for various applications.The combination of various signals disseminated and received forms various modes of satellite orbit determinations.If receivers at stations receive the own station-disseminated signals via a satellite transponder,it forms an orbit determination mode called "receiving the own station-disseminated signals mode".If receivers at all stations receive the signals disseminated from the master station via satellite transponders,it forms an orbit determination mode called "receiving the master station-disseminated signals mode".If all of receivers at stations receive all stations-disseminated signals via satellite transponders,it forms an orbit determination mode called "receiving all stations-disseminated signals mode".Also there are other combinations of signals for satellite orbit determination.For different orbit determination modes with different signal combinations,their rigorous formulae of processing are hereby presented in this paper.The accurate and the precise satellite orbit determination for both of the modes,"receiving the own station-disseminated signals mode" and "receiving the master station-disseminated signals mode" is attempted.It shows that the accuracy and precision for both of modes are nearly the same,the ranging accuracy is better than 1 cm,and the observation residuals of satellite orbit determination are better than 9 cm in the observation duration of 1 day.

  16. Particle swarm optimization applied to impulsive orbital transfers

    Science.gov (United States)

    Pontani, Mauro; Conway, Bruce A.

    2012-05-01

    The particle swarm optimization (PSO) technique is a population-based stochastic method developed in recent years and successfully applied in several fields of research. It mimics the unpredictable motion of bird flocks while searching for food, with the intent of determining the optimal values of the unknown parameters of the problem under consideration. At the end of the process, the best particle (i.e. the best solution with reference to the objective function) is expected to contain the globally optimal values of the unknown parameters. The central idea underlying the method is contained in the formula for velocity updating. This formula includes three terms with stochastic weights. This research applies the particle swarm optimization algorithm to the problem of optimizing impulsive orbital transfers. More specifically, the following problems are considered and solved with the PSO algorithm: (i) determination of the globally optimal two- and three-impulse transfer trajectories between two coplanar circular orbits; (ii) determination of the optimal transfer between two coplanar, elliptic orbits with arbitrary orientation; (iii) determination of the optimal two-impulse transfer between two circular, non-coplanar orbits; (iv) determination of the globally optimal two-impulse transfer between two non-coplanar elliptic orbits. Despite its intuitiveness and simplicity, the particle swarm optimization method proves to be capable of effectively solving the orbital transfer problems of interest with great numerical accuracy.

  17. Low-Energy Ballistic Transfers to Lunar Halo Orbits

    Science.gov (United States)

    Parker, Jeffrey S.

    2009-01-01

    Recent lunar missions have begun to take advantage of the benefits of low-energy ballistic transfers between the Earth and the Moon rather than implementing conventional Hohmann-like lunar transfers. Both Artemis and GRAIL plan to implement low-energy lunar transfers in the next few years. This paper explores the characteristics and potential applications of many different families of low-energy ballistic lunar transfers. The transfers presented here begin from a wide variety of different orbits at the Earth and follow several different distinct pathways to the Moon. This paper characterizes these pathways to identify desirable low-energy lunar transfers for future lunar missions.

  18. Interacting Binaries with Eccentric Orbits. Secular Orbital Evolution Due To Conservative Mass Transfer

    CERN Document Server

    Sepinsky, J F; Kalogera, V; Rasio, F A

    2007-01-01

    We investigate the secular evolution of the orbital semi-major axis and eccentricity due to mass transfer in eccentric binaries, assuming conservation of total system mass and orbital angular momentum. Assuming a delta function mass transfer rate centered at periastron, we find rates of secular change of the orbital semi-major axis and eccentricity which are linearly proportional to the magnitude of the mass transfer rate at periastron. The rates can be positive as well as negative, so that the semi-major axis and eccentricity can increase as well as decrease in time. Adopting a delta-function mass-transfer rate of $10^{-9} M_\\sun {\\rm yr}^{-1}$ at periastron yields orbital evolution timescales ranging from a few Myr to a Hubble time or more, depending on the binary mass ratio and orbital eccentricity. Comparison with orbital evolution timescales due to dissipative tides furthermore shows that tides cannot, in all cases, circularize the orbit rapidly enough to justify the often adopted assumption of instantan...

  19. Engine Optimization for a Solar Thermal Powered Orbit Transfer Vehicle

    Science.gov (United States)

    1998-06-01

    Recent technological advancements in solar thermal rocket propulsion and solar orbit transfer vehicles make it critical to perform additional engine performance analyses. Several system level flight demonstrations are imminent. Space flight hardware component testing is being conducted at the Air Force Research Laboratory, Edwards AFB, California. The focus of current research is engine and nozzle configurations for a solar orbit transfer vehicle. The optimal design must produce 1-10 pounds thrust, perform at high lsp and be compatible in a hybrid of spiral, perigee, and apogee (multi-burn) configurations. The nozzle material must not ablate when subjected to extreme thermal loading, yet be durable enough to withstand widely varying temperature differentials during frequent thermal cycling. This paper addresses propulsive needs in the orbit transfer arena and defines governing upper stage vehicle engine equations. These equations are modified versions of rocket engine equations used for chemical systems. The correction factors and modifications are for Solar Thermal Propulsion specific hardware.

  20. Interacting Binaries with Eccentric Orbits II. Secular Orbital Evolution Due To Non-Conservative Mass Transfer

    CERN Document Server

    Sepinsky, J F; Kalogera, V; Rasio, F A

    2009-01-01

    We investigate the secular evolution of the orbital semi-major axis and eccentricity due to mass transfer in eccentric binaries, allowing for both mass and angular momentum loss from the system. Adopting a delta function mass transfer rate at the periastron of the binary orbit, we find that, depending on the initial binary properties at the onset of mass transfer, the orbital semi-major axis and eccentricity can either increase or decrease at a rate linearly proportional to the magnitude of the mass transfer rate at periastron. The range of initial binary mass ratios and eccentricities that leads to increasing orbital semi-major axes and eccentricities broadens with increasing degrees of mass loss from the system and narrows with increasing orbital angular momentum loss from the binary. Comparison with tidal evolution timescales shows that the usual assumption of rapid circularization at the onset of mass transfer in eccentric binaries is not justified, irrespective of the degree of systemic mass and angular ...

  1. Angular dependence of spin-orbit spin-transfer torques

    KAUST Repository

    Lee, Ki-Seung

    2015-04-06

    In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

  2. Superfluid Helium On-Orbit Transfer (SHOOT) operations

    Science.gov (United States)

    Kittel, P.; Dipirro, M. J.

    1989-01-01

    The in-flight tests and the operational sequences of the Superfluid Helium On-Orbit Transfer (SHOOT) experiment are outlined. These tests include the transfer of superfluid helium at a variety of rates, the transfer into cold and warm receivers, the operation of an extravehicular activity coupling, and tests of a liquid acquisition device. A variety of different types of instrumentation will be required for these tests. These include pressure sensors and liquid flow meters that must operate in liquid helium, accurate thermometry, two types of quantity gauges, and liquid-vapor sensors.

  3. The K-1 Active Dispenser for Orbit Transfer

    Science.gov (United States)

    Lai, G.; Cochran, D.; Curtis, R.

    2002-01-01

    Kistler Aerospace Corporation is building the K-1, the world's first fully reusable launch vehicle. The two-stage K- 1 is designed primarily to service the market for low-earth orbit (LEO) missions, due to Kistler's need to recover both stages. For customers requiring payload delivery to high-energy orbits, Kistler can outfit the payload with a K- 1 Active Dispenser (an expendable third stage). The K-1 second stage will deploy the Active Dispenser mated with its payload into a 200 km circular LEO parking orbit. From this orbit, the Active Dispenser would use its own propulsion to place its payload into the final desired drop-off orbit or earth-escape trajectory. This approach allows Kistler to combine the low-cost launch services offered by the reusable two-stage K-1 with the versatility of a restartable, expendable upper stage. Enhanced with an Active Dispenser, the K-1 will be capable of delivering 1,500 kg to a geosynchronous transfer orbit or up to approximately 1,000 kg into a Mars rendezvous trajectory. The list price of a K-1 Active Dispenser launch is 25 million (plus the price of mission unique integration services) significantly less than the price of any launch vehicle service in the world with comparable capability.

  4. Optimal trajectories for LEO-to-LEO aeroassisted orbital transfer

    Science.gov (United States)

    Miele, A.; Lee, W. Y.; Mease, K. D.

    This paper considers both classical and minimax problems of optimal control arising in the study of noncoplanar, aeroassisted orbital transfer. The maneuver considered involves the transfer from one planetary orbit to another having different orbital inclination, but the same radius. An example is the LEO-to-LEO transfer of a spacecraft with a prescribed plane change, where LEO denotes low Earth orbit. The basic idea is to employ the hybrid combination of propulsive maneuvers in space and aerodynamic maneuvers in the sensible atmosphere. Hence, this type of flight is also called synergetic space flight. With reference to the atmospheric part of the maneuver, trajectory control is achieved by modulating the lift coefficient (hence, the angle of attack) and the angle of bank. The presence of upper and lower bounds on the lift coefficient is considered. Three different transfer maneuvers are studied. Type 1 involves four impulses and four space plane changes; Type 2 involves three impulses and three space plane changes; and Type 3 involves three impulses and no space plane change. In Type 1, the initial impulse directs the spacecraft away from Earth, and then is followed by an apogee impulse propelling the spacecraft toward Earth; in Types 2 and 3, the initial impulse directs the spacecraft toward Earth. A common element of these maneuvers is that they all include an atmospheric pass, with velocity depletion coupled with plane change. Within the framework of classical optimal control, the following problems are studied: (P1) minimize the energy required for orbital transfer; (P4) maximize the time of flight during the atmospheric portion of the trajectory; (P5) minimize the time integral of the square of the path inclination. Within the framework of minimax optimal control, the following problem is studied: (Q1) minimize the peak heating rate. Numerical solutions for Problems (P1), (P4), (P5), (Q1) are obtained by means of the sequential gradient-restoration algorithm

  5. Solar electric propulsion for the orbital transfer of large spacecraft to geosynchronous orbit

    Science.gov (United States)

    Garrison, James L.

    1992-01-01

    Low thrust trajectories utilizing electric propulsion and photovoltaic power sources are derived for the transfer of a large spacecraft from assembly in low earth orbit to operation at geosynchronous orbit. Conventional silicon photovoltaic devices are assumed. A 1 MeV equivalent electron flux model is used. The solar panel mass and size are taken from Advanced Photovoltaic Solar Array design concepts with 3-mil shielding. Shadowing of the vehicle and low earth orbit atmospheric drag are also modeled. The power system is sized so that end of life output is 30 percent of initial output. Steering of the thrust vector is defined by a three term series in which the coefficients are varied as controls to minimize the total power loss with cumulative exposure in the Van Allen region.

  6. Qualitative Properties of Orbits for Minimum-Fuel Impulsive Transfers between Circular Coplanar Orbits with a Given Launch Time

    Science.gov (United States)

    Kirpichnikov, S. N.; Vorobyev, A. Yu.; Teterin, S. N.

    2003-09-01

    The coplanar problem of minimizing propellant consumption in impulsive transfer between circular boundary orbits is investigated. The launch time and the initial configuration of objects on the boundary orbits are specified arbitrarily. The qualitative properties of optimal two-impulse trajectories and their optimality in the class of multi-impulse transfers are studied.

  7. Spin Orbit Interaction Engineering for beyond Spin Transfer Torque memory

    Science.gov (United States)

    Wang, Kang L.

    Spin transfer torque memory uses electron current to transfer the spin torque of electrons to switch a magnetic free layer. This talk will address an alternative approach to energy efficient non-volatile spintronics through engineering of spin orbit interaction (SOC) and the use of spin orbit torque (SOT) by the use of electric field to improve further the energy efficiency of switching. I will first discuss the engineering of interface SOC, which results in the electric field control of magnetic moment or magneto-electric (ME) effect. Magnetic memory bits based on this ME effect, referred to as magnetoelectric RAM (MeRAM), is shown to have orders of magnitude lower energy dissipation compared with spin transfer torque memory (STTRAM). Likewise, interests in spin Hall as a result of SOC have led to many advances. Recent demonstrations of magnetization switching induced by in-plane current in heavy metal/ferromagnetic heterostructures have been shown to arise from the large SOC. The large SOC is also shown to give rise to the large SOT. Due to the presence of an intrinsic extraordinarily strong SOC and spin-momentum lock, topological insulators (TIs) are expected to be promising candidates for exploring spin-orbit torque (SOT)-related physics. In particular, we will show the magnetization switching in a chromium-doped magnetic TI bilayer heterostructure by charge current. A giant SOT of more than three orders of magnitude larger than those reported in heavy metals is also obtained. This large SOT is shown to come from the spin-momentum locked surface states of TI, which may further lead to innovative low power applications. I will also describe other related physics of SOC at the interface of anti-ferromagnetism/ferromagnetic structure and show the control exchange bias by electric field for high speed memory switching. The work was in part supported by ERFC-SHINES, NSF, ARO, TANMS, and FAME.

  8. Low-Thrust Transfers from Distant Retrograde Orbits to L2 Halo Orbits in the Earth-Moon System

    Science.gov (United States)

    Parrish, Nathan L.; Parker, Jeffrey S.; Hughes, Steven P.; Heiligers, Jennette

    2016-01-01

    Enable future missions Any mission to a DRO or halo orbit could benefit from the capability to transfer between these orbits Chemical propulsion could be used for these transfers, but at high propellant cost Fill gaps in knowledge A variety of transfers using SEP or solar sails have been studied for the Earth-Moon system Most results in literature study a single transfer This is a step toward understanding the wide array of types of transfers available in an N-body force model.

  9. Emergence of a super-synchronized mobbing state in a large population of coupled chemical oscillators

    Science.gov (United States)

    Ghoshal, Gourab; Muñuzuri, Alberto P.; Pérez-Mercader, Juan

    2016-01-01

    Oscillatory phenomena are ubiquitous in Nature. The ability of a large population of coupled oscillators to synchronize constitutes an important mechanism to express information and establish communication among members. To understand such phenomena, models and experimental realizations of globally coupled oscillators have proven to be invaluable in settings as varied as chemical, biological and physical systems. A variety of rich dynamical behavior has been uncovered, although usually in the context of a single state of synchronization or lack thereof. Through the experimental and numerical study of a large population of discrete chemical oscillators, here we report on the unexpected discovery of a new phenomenon revealing the existence of dynamically distinct synchronized states reflecting different degrees of communication. Specifically, we discover a novel large-amplitude super-synchronized state separated from the conventionally reported synchronized and quiescent states through an unusual sharp jump transition when sampling the strong coupling limit. Our results assume significance for further elucidating globally coherent phenomena, such as in neuropathologies, bacterial cell colonies, social systems and semiconductor lasers.

  10. Transfer of optical orbital angular momentum to a bound electron

    Science.gov (United States)

    Schmiegelow, Christian T.; Schulz, Jonas; Kaufmann, Henning; Ruster, Thomas; Poschinger, Ulrich G.; Schmidt-Kaler, Ferdinand

    2016-10-01

    Photons can carry angular momentum, not only due to their spin, but also due to their spatial structure. This extra twist has been used, for example, to drive circular motion of microscopic particles in optical tweezers as well as to create vortices in quantum gases. Here we excite an atomic transition with a vortex laser beam and demonstrate the transfer of optical orbital angular momentum to the valence electron of a single trapped ion. We observe strongly modified selection rules showing that an atom can absorb two quanta of angular momentum from a single photon: one from the spin and another from the spatial structure of the beam. Furthermore, we show that parasitic ac-Stark shifts from off-resonant transitions are suppressed in the dark centre of vortex beams. These results show how light's spatial structure can determine the characteristics of light-matter interaction and pave the way for its application and observation in other systems.

  11. Orbit-to-ground Wireless Power Transfer test mission

    Science.gov (United States)

    Bergsrud, C.; Noghanian, S.; Straub, J.; Whalen, D.; Fevig, R.

    Since the 1970s the concept of transferring power from orbit for use on Earth has had a great deal of consideration for future energy and environmental sustainability here on Earth. The cost, size and complexity of a production-grade system are extremely large, and have many environmental considerations. There has never been a publicly disclosed orbit-to-ground power transfer test mission. A proposed project provides an opportunity to test the conceptual operation of such a system, albeit at a much lower power level than the `grand' or `real scale' system. During this test, a small Solar Powered (SP) 6-U CubSat will be deployed into Low-Earth Orbit (LEO) (225 or 325 km) to collect and store 1 KW of power from solar energy as the satellite is orbiting. The goal is to transmit 1 KW of wireless power at a microwave frequency of 5.8 or 10 GHz to a ground antenna array system. This paper presents the architecture for the proposed mission and discusses the regulatory, legal, and environmental issues that such a mission poses. Furthermore, the gain of the transmitter is analyzed at 20 and 30 dB as well as the gain of the receiver is analyzed at 30, 40, and 50 dB. A SP 6-U CubeSat will have a Lithium Ion (LIon) battery capable of storing enough energy for 83.33 Whr charge to run the satellites controls, and 1 KW necessary for a 5-minute demonstration and test (in addition to power required for its own operational requirements). Once charged, the satellite will use highly accurate position and attitude knowledge provided by an onboard star-tracker, Global Positioning Satellite (GPS) and inertial measurement unit to determine the proper orientation for the power transfer test. The onboard Attitude Determination and Control (ADCS) will be utilized to achieve and maintain this orientation during the test period. A cold-gas propulsion system will be available to de-spin the reaction wheels to ensure that sufficient ADCS capabilities exist for attitude-stabilization use during

  12. Optimal aeroassisted orbital transfer with plane change using collocation and nonlinear programming

    Science.gov (United States)

    Shi, Yun. Y.; Nelson, R. L.; Young, D. H.

    1990-01-01

    The fuel optimal control problem arising in the non-planar orbital transfer employing aeroassisted technology is addressed. The mission involves the transfer from high energy orbit (HEO) to low energy orbit (LEO) with orbital plane change. The basic strategy here is to employ a combination of propulsive maneuvers in space and aerodynamic maneuvers in the atmosphere. The basic sequence of events for the aeroassisted HEO to LEO transfer consists of three phases. In the first phase, the orbital transfer begins with a deorbit impulse at HEO which injects the vehicle into an elliptic transfer orbit with perigee inside the atmosphere. In the second phase, the vehicle is optimally controlled by lift and bank angle modulations to perform the desired orbital plane change and to satisfy heating constraints. Because of the energy loss during the turn, an impulse is required to initiate the third phase to boost the vehicle back to the desired LEO orbital altitude. The third impulse is then used to circularize the orbit at LEO. The problem is solved by a direct optimization technique which uses piecewise polynomial representation for the state and control variables and collocation to satisfy the differential equations. This technique converts the optimal control problem into a nonlinear programming problem which is solved numerically. Solutions were obtained for cases with and without heat constraints and for cases of different orbital inclination changes. The method appears to be more powerful and robust than other optimization methods. In addition, the method can handle complex dynamical constraints.

  13. Effect of perturbations on debris-to-debris orbital transfers: A quantitative analysis

    Science.gov (United States)

    Kumar, Kartik; Hekma, Enne; Agrawal, Abhishek; Topputo, Francesco

    2017-03-01

    We investigated the applicability of the Lambert solver (Izzo, 2014) for preliminary design of Multi-Target Active Debris Removal missions. Firstly, we computed ≈25 million debris-to-debris transfers using the Lambert solver for selected sets of debris objects in Low Earth Orbit, Geostationary Transfer Orbit, and Geosynchronous Orbit. Subsequently, we propagated the departure states of the Lambert transfers below selected ΔV cut-offs using the SGP4/SDP4 propagator (Vallado et al., 2006). We recorded the arrival position and velocity error vectors incurred by neglecting perturbations and analyzed the results for each orbital regime. Our results indicate that perturbations can play a significant role in determining the feasibility of debris-to-debris transfers. By using the Lambert solver and neglecting perturbations, the errors in the arrival position and velocity for individual legs can be large. The largest errors were obtained for transfers between debris objects in Sun-Synchronous Orbit (O (100) km error in magnitude of position vector and O (0.1) km/s error in magnitude of velocity vector). Hence, solely employing the Lambert solver to rank transfer legs could lead to incorrect choices for sequencing of multi-target trajectories. This is particularly relevant for transfers in Low Earth Orbit, where the effects of perturbations are the strongest.

  14. Low-Thrust Transfer Design of Low-Observable Geostationary Earth Orbit Satellite

    Directory of Open Access Journals (Sweden)

    Bing Hua

    2015-01-01

    Full Text Available With radar and surface-to-air missiles posing an increasing threat to on-orbit spacecraft, low-observable satellites play an important role in low-thrust transfers. This paper presents the design for a low-thrust geostationary earth orbit (GEO transfer control strategy which takes into consideration the low-observable constraint and discusses Earth shadow and perturbation. A control parameter optimization addresses the orbit transfer problem, and five thrust modes are used. Simulation results show that the method outlined in this paper is simple and feasible and results in reduced transfer time with a small amount of calculation. The method therefore offers a useful reference for low-thrust GEO transfer design.

  15. Application of Super-Synchronization Speed Control Technology in Two 80 MVA Motor-Generator Units of HL-2A

    Institute of Scientific and Technical Information of China (English)

    LI Huajun; WANG Fen; WANG Xiaoping; DU Chang; XUAN Weiming; PEN Jianfei; HU Haotian; LIU Lin; KANG Li; XU Lirong; HUANG Zhaorong

    2007-01-01

    Two sets of super-synchronization speed control assemblies for two 80 MVA motorgenerator units have been developed successfully in order to satisfy the demand of the toroidal field system in the HL-2A tokamak.Based on the three-phase logical no-circumfluence a.c./a.c.cycloconverter,the speeds of two 2500 kW double fed drive motors have been regulated by means of the vector control technology.The maximum operating speed of each motor- generator unit has been raised from 1488 rpm (revolutions per minute) to 1650 rpm and the released energy of each unit during a pulsed discharge can reach 500 MJ.As a result,the toroidal field system has the capacity to provide 2.8 tesla (T) in HL-2A experiments.

  16. Application of Super-Synchronization Speed Control Technology in Two 80 MVA Motor-Generator Units of HL-2A

    Science.gov (United States)

    Li, Huajun; Du, Chang; Xuan, Weiming; Pen, Jianfei; Hu, Haotian; Liu, Lin; Kang, Li; Xu, Lirong; Huang, Zhaorong; Wang, Fen; Wang, Xiaoping

    2007-04-01

    Two sets of super-synchronization speed control assemblies for two 80 MVA motor-generator units have been developed successfully in order to satisfy the demand of the toroidal field system in the HL-2A tokamak. Based on the three-phase logical no-circumfluence a.c./a.c. cycloconverter, the speeds of two 2500 kW double fed drive motors have been regulated by means of the vector control technology. The maximum operating speed of each motor- generator unit has been raised from 1488 rpm (revolutions per minute) to 1650 rpm and the released energy of each unit during a pulsed discharge can reach 500 MJ. As a result, the toroidal field system has the capacity to provide 2.8 tesla (T) in HL-2A experiments.

  17. Transfer of orbital angular momentum through sub-wavelength waveguides.

    Science.gov (United States)

    Wang, Yanqin; Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Luo, Xiangang

    2015-02-01

    Data capacity of optical communication is achieving its limit owing to the non-linear effect of optical fiber. As an effective alternative, light carrying orbital angular momentum can greatly increase the capacity for its unprecedented degree of freedom. We demonstrate the propagation of orbital angular momentum with topological charge of 1 and 2 in plasmonic circular waveguide with sub-wavelength diameter with little propagation loss of 2.73 dB/μm, which has never been observed in optical fibers with sub-wavelength diameter. We also confirm that lights carrying orbital angular momentum can be maintained in sharp bended sub-wavelength waveguide. This plasmonic waveguide may serve as a key component in on-chip systems involving OAM.

  18. Low-Thrust Orbital Transfers in the Two-Body Problem

    Directory of Open Access Journals (Sweden)

    A. A. Sukhanov

    2012-01-01

    Full Text Available Low-thrust transfers between given orbits within the two-body problem are considered; the thrust is assumed power limited. A simple method for obtaining the transfer trajectories based on the linearization of the motion near reference orbits is suggested. Required calculation accuracy can be reached by means of use of a proper number of the reference orbits. The method may be used in the case of a large number of the orbits around the attracting center; no averaging is necessary in this case. The suggested method also is applicable to the cases of partly given final orbit and if there are constraints on the thrust direction. The method gives an optimal solution to the linearized problem which is not optimal for the original nonlinear problem; the difference between the optimal solutions to the original and linearized problems is estimated using a numerical example. Also examples illustrating the method capacities are given.

  19. Algebraic Approach to the Minimum-Cost Multi-Impulse Orbit-Transfer Problem

    Science.gov (United States)

    Avendaño, M.; Martín-Molina, V.; Martín-Morales, J.; Ortigas-Galindo, J.

    2016-08-01

    We present a purely algebraic formulation (i.e. polynomial equations only) of the minimum-cost multi-impulse orbit transfer problem without time constraints, while keeping all the variables with a precise physical meaning. We apply general algebraic techniques to solve these equations (resultants, Gr\\"obner bases, etc.) in several situations of practical interest of different degrees of generality. For instance, we provide a proof of the optimality of the Hohmann transfer for the minimum fuel 2-impulse circular to circular orbit transfer problem, and we provide a general formula for the optimal 2-impulse in-plane transfer between two rotated elliptical orbits under a mild symmetry assumption on the two points where the impulses are applied (which we conjecture that can be removed).

  20. Lyapunov-based Low-thrust Optimal Orbit Transfer: An approach in Cartesian coordinates

    CERN Document Server

    Zhang, Hantian; Cao, Qingjie

    2014-01-01

    This paper presents a simple approach to low-thrust optimal-fuel and optimal-time transfer problems between two elliptic orbits using the Cartesian coordinates system. In this case, an orbit is described by its specific angular momentum and Laplace vectors with a free injection point. Trajectory optimization with the pseudospectral method and nonlinear programming are supported by the initial guess generated from the Chang-Chichka-Marsden Lyapunov-based transfer controller. This approach successfully solves several low-thrust optimal problems. Numerical results show that the Lyapunov-based initial guess overcomes the difficulty in optimization caused by the strong oscillation of variables in the Cartesian coordinates system. Furthermore, a comparison of the results shows that obtaining the optimal transfer solution through the polynomial approximation by utilizing Cartesian coordinates is easier than using orbital elements, which normally produce strongly nonlinear equations of motion. In this paper, the Eart...

  1. Transferring orbital and spin angular momenta of light to atoms

    Energy Technology Data Exchange (ETDEWEB)

    Picon, A; Benseny, A; Mompart, J [Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Vazquez de Aldana, J R; Plaja, L [Servicio Laser, Universidad de Salamanca, E-37008 Salamanca (Spain); Calvo, G F [Mathematics Department and IMACI-Institute of Applied Mathematics in Science and Engineering, Universidad de Castilla-La Mancha, E-13071 Ciudad Real (Spain); Roso, L, E-mail: antonio.picon@uab.ca [Centro de Laseres Pulsados, CLPU, Patio de Escuelas 1, E-37008 Salamanca (Spain)

    2010-08-15

    Light beams carrying orbital angular momentum (OAM), such as Laguerre-Gaussian (LG) beams, give rise to the violation of the standard dipolar selection rules during interaction with matter, yielding, in general, an exchange of angular momentum larger than {h_bar} per absorbed photon. By means of ab initio three-dimensional (3D) numerical simulations, we investigate in detail the interaction of a hydrogen atom with intense Gaussian and LG light pulses. We analyze the dependence of the angular momentum exchange with the polarization, the OAM and the carrier-envelope phase of light, as well as with the relative position between the atom and the light vortex. In addition, a quantum-trajectory approach based on the de Broglie-Bohm formulation of quantum mechanics is used to gain physical insight into the absorption of angular momentum by the hydrogen atom.

  2. Synergetic plane-change capability of a conceptual aeromaneuvering-orbital-transfer vehicle

    Science.gov (United States)

    Menees, Gene P.; Wilson, John F.; Adelman, Henry G.

    1987-01-01

    The flight strategy for a general low-earth orbit plane-change is analyzed for a conceptual, high-lift, aeromaneuvering-orbital-transfer vehicle, and applied to the important case of the 45 deg plane-inclination change. The study focuses on two principal methods: (1) the procedure to obtain a change in the inclination of the vehicle's orbital plane, and (2) the full rendezvous procedure. Optimal trajectories for minimal propellant use during the synergetic aerotransit are developed, which incorporate best estimates of constraints imposed by reusable thermal-protection requirements and human tolerance to g-load levels. The performance capability for one-way payload delivery to the target orbit is analyzed in detail and the capability for return to the base orbit demonstrated.

  3. Optical orbital angular momentum conservation during the transfer process from plasmonic vortex lens to light.

    Science.gov (United States)

    Yu, Haohai; Zhang, Huaijin; Wang, Yicheng; Han, Shuo; Yang, Haifang; Xu, Xiangang; Wang, Zhengping; Petrov, V; Wang, Jiyang

    2013-11-12

    We demonstrate the optical orbital angular momentum conservation during the transfer process from subwavelength plasmonic vortex lens (PVLs) to light and the generating process of surface plasmon polaritons (SPPs). Illuminating plasmonic vortex lenses with beams carrying optical orbital angular momentum, the SP vortices with orbital angular momentum were generated and inherit the optical angular momentum of light beams and PVLs. The angular momentum of twisting SP electromagnetic field is tunable by the twisted metal/dielectric interfaces of PVLs and angular momentum of illuminating singular light. This work may open the door for several possible applications of SP vortices in subwavelength region.

  4. Polyhedral representation of invariant manifolds applied to orbit transfers in the Earth-Moon system

    Science.gov (United States)

    Pontani, Mauro; Teofilatto, Paolo

    2016-02-01

    Recently, manifold dynamics has assumed an increasing relevance for analysis and design of low-energy missions, both in the Earth-Moon system and in alternative multibody environments. This work proposes and describes an intuitive polyhedral interpolative approach for each state component associated with manifold trajectories, both in two and in three dimensions. An adequate grid of data, coming from the numerical propagation of a finite number of manifold trajectories, is employed. Accuracy of this representation is evaluated with reference to the invariant manifolds associated with a two-dimensional Lyapunov orbit and a three-dimensional Halo orbit, and is proven to be satisfactory, with the exclusion of limited regions of the manifolds. As a first, preliminary application, the polyhedral interpolation technique allows identifying the orbits in the proximity of the interior collinear libration point as either asymptotic, transit, or bouncing trajectories. Then, two applications to orbital maneuvering are addressed. First, the globally optimal two-impulse transfer between a specified low Earth orbit and a Lyapunov orbit (through its stable manifold) is determined. Second, the minimum-time low-thrust transfer from the same terminal orbits is found using again the stable manifold. These applications prove the effectiveness of the polyhedral interpolative technique and represent the premise for its application also to different problems involving invariant manifold dynamics.

  5. Maximum orbit plane change with heat-transfer-rate considerations

    Science.gov (United States)

    Lee, J. Y.; Hull, D. G.

    1990-01-01

    Two aerodynamic maneuvers are considered for maximizing the plane change of a circular orbit: gliding flight with a maximum thrust segment to regain lost energy (aeroglide) and constant altitude cruise with the thrust being used to cancel the drag and maintain a high energy level (aerocruise). In both cases, the stagnation heating rate is limited. For aeroglide, the controls are the angle of attack, the bank angle, the time at which the burn begins, and the length of the burn. For aerocruise, the maneuver is divided into three segments: descent, cruise, and ascent. During descent the thrust is zero, and the controls are the angle of attack and the bank angle. During cruise, the only control is the assumed-constant angle of attack. During ascent, a maximum thrust segment is used to restore lost energy, and the controls are the angle of attack and bank angle. The optimization problems are solved with a nonlinear programming code known as GRG2. Numerical results for the Maneuverable Re-entry Research Vehicle with a heating-rate limit of 100 Btu/ft(2)-s show that aerocruise gives a maximum plane change of 2 deg, which is only 1 deg larger than that of aeroglide. On the other hand, even though aerocruise requires two thrust levels, the cruise characteristics of constant altitude, velocity, thrust, and angle of attack are easy to control.

  6. Minimum fuel coplanar aeroassisted orbital transfer using collocation and nonlinear programming

    Science.gov (United States)

    Shi, Yun Yuan; Young, D. H.

    1991-01-01

    The fuel optimal control problem arising in coplanar orbital transfer employing aeroassisted technology is addressed. The mission involves the transfer from high energy orbit (HEO) to low energy orbit (LEO) without plane change. The basic approach here is to employ a combination of propulsive maneuvers in space and aerodynamic maneuvers in the atmosphere. The basic sequence of events for the coplanar aeroassisted HEO to LEO orbit transfer consists of three phases. In the first phase, the transfer begins with a deorbit impulse at HEO which injects the vehicle into a elliptic transfer orbit with perigee inside the atmosphere. In the second phase, the vehicle is optimally controlled by lift and drag modulation to satisfy heating constraints and to exit the atmosphere with the desired flight path angle and velocity so that the apogee of the exit orbit is the altitude of the desired LEO. Finally, the second impulse is required to circularize the orbit at LEO. The performance index is maximum final mass. Simulation results show that the coplanar aerocapture is quite different from the case where orbital plane changes are made inside the atmosphere. In the latter case, the vehicle has to penetrate deeper into the atmosphere to perform the desired orbital plane change. For the coplanar case, the vehicle needs only to penetrate the atmosphere deep enough to reduce the exit velocity so the vehicle can be captured at the desired LEO. The peak heating rates are lower and the entry corridor is wider. From the thermal protection point of view, the coplanar transfer may be desirable. Parametric studies also show the maximum peak heating rates and the entry corridor width are functions of maximum lift coefficient. The problem is solved using a direct optimization technique which uses piecewise polynomial representation for the states and controls and collocation to represent the differential equations. This converts the optimal control problem into a nonlinear programming problem

  7. Orbit Transfers for Dawn's Vesta Operations : Navigation and Mission Design Experience

    Science.gov (United States)

    Han, Dongsuk

    2012-01-01

    Dawn, a mission belonging to NASA's Discovery Program, was launched on September 27, 2007 to explore main belt asteroids in order to yield insights into important questions about the formation and evolution of the solar system. From July of 2011 to August of 2012, the Dawn spacecraft successfully returned valuable science data, collected during the four planned mapping orbits at its first target asteroid, Vesta. Each mapping orbit was designed to enable a different set of scientific observations. Such a mission would have been impossible without the low thrust ion propulsion system (IPS). Maneuvering a spacecraft using only the IPS for the transfers between the mapping orbits posed many technical challenges to Dawn's flight team at NASA's Jet Propulsion Laboratory. Each transfer needs a robust plan that accounts for uncertainties in maneuver execution, orbit determination, and physical characteristics of Vesta. This paper discusses the mission design and navigational experience during Dawn's Vesta operations. Topics include requirements and constraints from Dawn's science and spacecraft teams, orbit determination and maneuver design and building process for transfers, developing timelines for thrust sequence build cycles, and the process of scheduling very demanding coverage with ground antennae at NASA's Deep Space Network.

  8. Tangent-impulse transfer from elliptic orbit to an excess velocity vector

    Institute of Scientific and Technical Information of China (English)

    Zhang Gang; Zhang Xiangyu; Cao Xibin

    2014-01-01

    The two-body orbital transfer problem from an elliptic parking orbit to an excess veloc-ity vector with the tangent impulse is studied. The direction of the impulse is constrained to be aligned with the velocity vector, then speed changes are enough to nullify the relative velocity. First, if one tangent impulse is used, the transfer orbit is obtained by solving a single-variable function about the true anomaly of the initial orbit. For the initial circular orbit, the closed-form solution is derived. For the initial elliptic orbit, the discontinuous point is solved, then the initial true anomaly is obtained by a numerical iterative approach; moreover, an alternative method is proposed to avoid the singularity. There is only one solution for one-tangent-impulse escape trajectory. Then, based on the one-tangent-impulse solution, the minimum-energy multi-tangent-impulse escape trajectory is obtained by a numerical optimization algorithm, e.g., the genetic method. Finally, several examples are provided to validate the proposed method. The numerical results show that the minimum-energy multi-tangent-impulse escape trajectory is the same as the one-tangent-impulse trajectory.

  9. Tangent-impulse transfer from elliptic orbit to an excess velocity vector

    Directory of Open Access Journals (Sweden)

    Zhang Gang

    2014-06-01

    Full Text Available The two-body orbital transfer problem from an elliptic parking orbit to an excess velocity vector with the tangent impulse is studied. The direction of the impulse is constrained to be aligned with the velocity vector, then speed changes are enough to nullify the relative velocity. First, if one tangent impulse is used, the transfer orbit is obtained by solving a single-variable function about the true anomaly of the initial orbit. For the initial circular orbit, the closed-form solution is derived. For the initial elliptic orbit, the discontinuous point is solved, then the initial true anomaly is obtained by a numerical iterative approach; moreover, an alternative method is proposed to avoid the singularity. There is only one solution for one-tangent-impulse escape trajectory. Then, based on the one-tangent-impulse solution, the minimum-energy multi-tangent-impulse escape trajectory is obtained by a numerical optimization algorithm, e.g., the genetic method. Finally, several examples are provided to validate the proposed method. The numerical results show that the minimum-energy multi-tangent-impulse escape trajectory is the same as the one-tangent-impulse trajectory.

  10. 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.

  11. The role of solar apsidal resonance in the evolution of geostationary transfer orbits

    Science.gov (United States)

    Wang, Yue; Gurfil, Pini

    2017-04-01

    Subjected to multiple perturbations and their complex interplay, the dynamical evolution of geostationary transfer orbits (GTOs) is sensitive to initial conditions and model parameters. As one of the most remarkable outcomes of multiple perturbations, the solar apsidal resonance, i.e., the 1:1 resonance between the solar orbital motion and the rotation of the orbital apsidal line caused by Earth's oblateness, is an important feature of the GTO evolution. It occurs when the semi-major axis is reduced by the atmospheric drag to the critical value, with which the rotation of the orbital apsidal line is commensurate with the solar orbital motion. In the present paper, we show that the solar apsidal resonance plays an important role in the evolution and decay of GTOs. To do so, we first explain the underlying dynamical mechanism of the solar apsidal resonance, which is the U-turn of the solar azimuth with respect to the orbital apsidal line and the resulting monotonic increase or decrease of the eccentricity. The resonance is then classified into three kinds, and their causes and effects are analyzed. Previous studies have regarded the solar apsidal resonance as a mechanism extending the orbital lifetime. However, we find that in most cases the GTO will re-enter Earth's atmosphere soon or only several years after the resonance, and so the solar apsidal resonance can be regarded as the prelude to the GTO final re-entry. Finally, the sensitivity of orbital dynamics is studied through numerical simulations. It is shown that the high sensitivity of the dynamics can be attributed to the resonance, which is difficult to predict or manage. With the initial state, it is possible to predict the orbit evolution of GTO only before the solar apsidal resonance. To predict the lifetime of GTO, new measurements on the orbit after the resonance are required.

  12. Space-to-Space Power Beaming Enabling High Performance Rapid Geocentric Orbit Transfer

    Science.gov (United States)

    Dankanich, John W.; Vassallo, Corinne; Tadge, Megan

    2015-01-01

    The use of electric propulsion is more prevalent than ever, with industry pursuing all electric orbit transfers. Electric propulsion provides high mass utilization through efficient propellant transfer. However, the transfer times become detrimental as the delta V transitions from near-impulsive to low-thrust. Increasing power and therefore thrust has diminishing returns as the increasing mass of the power system limits the potential acceleration of the spacecraft. By using space-to-space power beaming, the power system can be decoupled from the spacecraft and allow significantly higher spacecraft alpha (W/kg) and therefore enable significantly higher accelerations while maintaining high performance. This project assesses the efficacy of space-to-space power beaming to enable rapid orbit transfer while maintaining high mass utilization. Concept assessment requires integrated techniques for low-thrust orbit transfer steering laws, efficient large-scale rectenna systems, and satellite constellation configuration optimization. This project includes the development of an integrated tool with implementation of IPOPT, Q-Law, and power-beaming models. The results highlight the viability of the concept, limits and paths to infusion, and comparison to state-of-the-art capabilities. The results indicate the viability of power beaming for what may be the only approach for achieving the desired transit times with high specific impulse.

  13. Trajectory and Correction Maneuver During the Transfer from Earth to Halo Orbit

    Institute of Scientific and Technical Information of China (English)

    Xu Ming; Xu Shijie

    2008-01-01

    This article addresses the design of the trajectory transferring fi'om Earth to Halo orbit,and proposes a timing closed-loop strategy of correction maneuver during the trausfer in the frame of circular restricted three body problem (CR3BP).The relation between the Floquet multipliers and the magnitudes of Halo orbit is established,so that the suitable magnitude for the aerospace mission is chosen in previous researches,and six types of single-impulse transfer trajectories are attained from the geometry of the invariant manifolds.Based on one of the trajectories of indirect transfer which arc ignored in the most of literatures,the stochastic control theory for imperfect information of the discrete linear stochastic system is applied to design the trajectory correction maneuver.The statistical dispersion analysis is performed by Monte-Carlo simulation.

  14. Low-thrust orbit transfer optimization with refined Q-law and multi-objective genetic algorithm

    Science.gov (United States)

    Lee, Seungwon; Petropoulos, Anastassios E.; von Allmen, Paul

    2005-01-01

    An optimization method for low-thrust orbit transfers around a central body is developed using the Q-law and a multi-objective genetic algorithm. in the hybrid method, the Q-law generates candidate orbit transfers, and the multi-objective genetic algorithm optimizes the Q-law control parameters in order to simultaneously minimize both the consumed propellant mass and flight time of the orbit tranfer. This paper addresses the problem of finding optimal orbit transfers for low-thrust spacecraft.

  15. Coupled attitude-orbit dynamics and control for an electric sail in a heliocentric transfer mission.

    Directory of Open Access Journals (Sweden)

    Mingying Huo

    Full Text Available The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.

  16. Coupled attitude-orbit dynamics and control for an electric sail in a heliocentric transfer mission.

    Science.gov (United States)

    Huo, Mingying; Zhao, Jun; Xie, Shaobiao; Qi, Naiming

    2015-01-01

    The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.

  17. Phasing Delta-V for transfers from Sun-Earth halo orbits to the Moon

    Science.gov (United States)

    Chen, Hongru; Kawakatsu, Yasuhiro; Hanada, Toshiya

    2016-10-01

    Inspired by successful extended missions such as the ISEE-3, an investigation for the extended mission that involves a lunar encounter following a Sun-Earth halo orbit mission is considered valuable. Most previous studies present the orbit-to-orbit transfers where the lunar phase is not considered. Intended for extended missions, the present work aims to solve for the minimum phasing ∆V for various initial lunar phases. Due to the solution multiplicity of the two-point boundary value problem, the general constrained optimization algorithm that does not identify multiple feasible solutions is shown to miss minima. A two-step differential corrector with a two-body Lambert solver is developed for identifying multiple solutions. The minimum ∆V associated with the short-way and long-way approaches can be recovered. It is acquired that the required ∆V to cover all initial lunar phases is around 45 m/s for the halo orbit with out-of-plane amplitude Az greater than 3.5×105 km, and 14 m/s for a small halo orbit with Az=1×105 km. In addition, the paper discusses the phasing planning based on the ∆V result and the shift of lunar phase with halo orbit revolution.

  18. Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

    Energy Technology Data Exchange (ETDEWEB)

    Alexeyev, C. N.; Volyar, A. V. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Yavorsky, M. A. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Universite Bordeaux and CNRS, LOMA, UMR 5798, FR-33400 Talence (France)

    2011-12-15

    We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over the array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.

  19. Transfer Maneuvers Between Periodic Earth-Moon Orbits Using Stable an Unstable Manifolds

    Science.gov (United States)

    Marcuzzi, J. P.; Leiva, A. M.; Briozzo, C. B.

    In this paper we have determined the stable and unstable manifold of six unstable periodic orbits (h=-1,586656) in an appropriate surface of section in the Earth-Moon coplanar circular restricted three body problem. The cost diagrams give account of a low transfer tax on using this technique and they would allow to determine the lower cost regions in order to apply the required propellent in each maneuver. FULL TEXT IN SPANISH

  20. Catalytic surface effect on ceramic coatings for an aeroassisted orbital transfer vehicle

    Science.gov (United States)

    Steward, D. A.; Leiser, D. B.

    1984-01-01

    Surface catalytic efficiencies of glassy coatings were determined from a reaction boundary layer computation and arc-jet data. The catalytic efficiencies of the various coatings examined are discussed in terms of their reaction-rate constants. These constants are a function of the wall temperature (1290 K to 2000 K). In addition, the advantage of a thermal protection system for a bent biconic, aeroassisted orbital transfer vehicle with a low surface catalytic efficiency is discussed.

  1. Understanding Spacecraft Agility for Orbit Transfers on the Dawn Low-thrust Mission

    Science.gov (United States)

    Smith, Brett A.; Vanelli, C. Anthony; Lee, Allan Y.

    2012-01-01

    Conventional maneuver design processes were inadequate. Long thrusting durations with the small force of SEP. Increased coupling between ACS and NAV teams. Definition of quantifiable constraints proved impractical. Specifically for the Dawn mission, because of the attitude steering algorithm. A time-efficient simulation tool, qSTAT, was developed and allowed fast verification of candidate thrust profile designs. This approach allowed Dawn to overcome the complications of low-thrust orbit transfers.

  2. Thrust vector control of upper stage with a gimbaled thruster during orbit transfer

    Science.gov (United States)

    Wang, Zhaohui; Jia, Yinghong; Jin, Lei; Duan, Jiajia

    2016-10-01

    In launching Multi-Satellite with One-Vehicle, the main thruster provided by the upper stage is mounted on a two-axis gimbal. During orbit transfer, the thrust vector of this gimbaled thruster (GT) should theoretically pass through the mass center of the upper stage and align with the command direction to provide orbit transfer impetus. However, it is hard to be implemented from the viewpoint of the engineering mission. The deviations of the thrust vector from the command direction would result in large velocity errors. Moreover, the deviations of the thrust vector from the upper stage mass center would produce large disturbance torques. This paper discusses the thrust vector control (TVC) of the upper stage during its orbit transfer. Firstly, the accurate nonlinear coupled kinematic and dynamic equations of the upper stage body, the two-axis gimbal and the GT are derived by taking the upper stage as a multi-body system. Then, a thrust vector control system consisting of the special attitude control of the upper stage and the gimbal rotation of the gimbaled thruster is proposed. The special attitude control defined by the desired attitude that draws the thrust vector to align with the command direction when the gimbal control makes the thrust vector passes through the upper stage mass center. Finally, the validity of the proposed method is verified through numerical simulations.

  3. Spiraling Away from Vesta: Design of the Transfer from the Low to High Altitude Dawn Mapping Orbits

    Science.gov (United States)

    Smith, John C.; Parcher, Daniel W.; Whiffen, Gregory J.

    2013-01-01

    Dawn has successfully completed its orbital mission at Vesta and is currently en route to an orbital rendezvous with Ceres in 2015. The longest duration and most complex portion of the Vesta departure trajectory was the transfer from the low to high altitude science orbit. This paper describes the design of this low-thrust trajectory optimized assuming a minimum-propellant mass objective. The transfer utilized solar-electric ion propulsion applied over 139 spacecraft revolutions about Vesta. Science drivers, operational constraints, and robustness to statistical uncertainties are addressed. The 45-day transfer trajectory was successfully implemented in early 2012.

  4. Cryogenic On-Orbit Liquid Depot Storage, Acquisition, and Transfer Satellite (COLD-SAT)

    Science.gov (United States)

    Schuster, John R.; Russ, Edwin J.; Wachter, Joseph P.

    1990-01-01

    The Cryogenic On-Orbit Liquid Depot Storage, Acquisition, and Transfer Satellite (COLD-SAT) will perform subcritical liquid hydrogen handling experiments under low gravity conditions to provide engineering data for future space transportation missions. Comprising the four Class 1 enabling experiments are tank press control, tank chilldown, tank no-vent fill, and liquid acquisition device fill/refill. The nine Class 2 enhancing experiments are tanker thermal performance, pressurization, low-gravity setting and outflow, liquid acquisition device performance, transfer line chilldown, outflow subcooling, low-gravity vented fill, fluid dumping, and advanced instrumentation. Consisting of an experiment module mated to a spacecraft bus, COLD-SAT will be placed in an initial 1300 km circular orbit by an Atlas commercial launch vehicle, and will perform experiments in a semi-autonomous mode for a period of up to six months. The three-axis controlled spacecraft bus provides electric power, control and data management, communications, and attitude control along with propulsive acceleration levels ranging from 10(exp -6) to 10(exp -4) g. It is desired to understand the effects that low acceleration levels might have on the heat and mass transfer processes involved in some of the experiments. The experiment module contains the three liquid hydrogen tanks, valves, pressurization and pumping equipment, and instrumentation. Within the highly insulated tanks are specialized fluid management equipment that might be used in future space transportation systems. At launch all the liquid hydrogen for the experiments is contained in the largest tank, which has helium-purged insulation to prevent cryo-pumping of air on the launch pad. The tank is loaded by the hydrogen tanking system used for the Centaur upper stage of the Atlas. After reaching orbit the two smaller tanks become receivers for fluid transfers, and when tanked, become the vessels for performing many of the experiments.

  5. Shuttle and Transfer Orbit Thermal Analysis and Testing of the Chandra X-Ray Observatory CCD Imaging Spectrometer Radiator Shades

    Science.gov (United States)

    Sharp, John R.

    2001-01-01

    Contents include the following: (1) Introduction: Chandra X-ray observatory. Advanced CCD imaging spectrometer. (2) LEO and transfer orbit analyses: Geometric modeling in TSS w/specularity. Low earth orbital heating calculations. (3) Thermal testing and LMAC. (4) Problem solving. (5) VDA overcoat analyses. (6) VDA overcoat testing and MSFC. (7) Post-MSFC test evaluation.

  6. Shape similarity of charge-transfer (CT) excitation energy curves in a series of donor-acceptor complexes and its description with a transferable energy of CT orbital

    Science.gov (United States)

    Gritsenko, O. V.

    2017-08-01

    A simple nature of charge-transfer (CT) in the prototype complexes Dp -F2 (Dp =NH3 , H2O) manifests itself in a very close shape of their CT excitation energy curves ωCT (R) along the donor-acceptor separation R. It affords a simple orbital description in terms of the CT orbitals (CTOs) obtained with a transformation of the virtual orbitals of the standard local density approximation (LDA). The transferable energy of the relevant CTO as a function of R closely approximates the common shape of ωCT (R) , while the height of the individual curve is determined with the ionization potential of Dp .

  7. Optical and thermal characterization of membrane reflector materials for solar orbit transfer vehicles

    Science.gov (United States)

    Farmer, Gregory D.; McGee, Jennie K.; Partch, Russell; Lester, Dean M.

    2002-01-01

    The Air Force Research Laboratory (AFRL), is advancing technologies to enable greater mobility for future AF spacecraft. The Solar Orbit Transfer Vehicle (SOTV) program is developing components for a concept based on a solar thermal rocket and solar thermal power generation. The program is performing ground testing of a thin film membrane concentrator concept. To better understand system performance, a series of optical characterization tests of the membrane material were performed. The objective was to quantify the relationship between membrane optical properties and the concentrator on-orbit transmission performance and thermal profile. During testing we collected reflectivity, absorptivity, transmissivity, and emissivity data for un-coated and coated membrane material. The membrane material tested was fabricated using a flight-qualified polyimide material and proven manufacturing processes. The test results, and system thermal analysis are presented in this paper. The results of this research will be used to refine hardware performance predictions and improve sizing for flight demonstration. .

  8. Linear Energy Transfer (LET) spectra of cosmic radiation in low Earth orbit

    Science.gov (United States)

    Parnell, T. A.; Watts, J. W., Jr.; Akopova, A. B.; Magradze, N. V.; Dudkin, V. E.; Kovalev, E. E.; Potapov, Yu. V.; Benton, E. V.; Frank, A. L.; Benton, E. R.

    1995-01-01

    Integral linear energy transfer (LET) spectra of cosmic radiation (CR) particles were measured on five Cosmos series spacecraft in low Earth orbit (LEO). Particular emphasis is placed on results of the Cosmos 1887 biosatellite which carried a set of joint U.S.S.R.-U.S.A. radiation experiments involving passive detectors that included thermoluminescent detectors (TLD's), plastic nuclear track detectors (PNTD's), fission foils, nuclear photo-emulsions, etc. which were located both inside and outside the spacecraft. Measured LET spectra are compared with those theoretically calculated. Results show that there is some dependence of LET spectra on orbital parameters. The results are used to estimate the CR quality factor (QF) for the COSMOS 1887 mission.

  9. Studies on fluid dynamics of the flow field and gas transfer in orbitally shaken tubes.

    Science.gov (United States)

    Zhu, Li-Kuan; Song, Bo-Yan; Wang, Zhen-Long; Monteil, Dominique T; Shen, Xiao; Hacker, David L; De Jesus, Maria; Wurm, Florian M

    2017-01-01

    Orbitally shaken cylindrical bioreactors [OrbShake bioreactors (OSRs)] without an impeller or sparger are increasingly being used for the suspension cultivation of mammalian cells. Among small volume OSRs, 50-mL tubes with a ventilated cap (OSR50), originally derived from standard laboratory centrifuge tubes with a conical bottom, have found many applications including high-throughput screening for the optimization of cell cultivation conditions. To better understand the fluid dynamics and gas transfer rates at the liquid surface in OSR50, we established a three-dimensional simulation model of the unsteady liquid forms (waves) in this vessel. The studies verified that the operating conditions have a large effect on the interfacial surface. The volumetric mass transfer coefficient (kL a) was determined experimentally and from simulations under various working conditions. We also determined the liquid-phase mass transfer coefficient (kL ) and the specific interfacial area (a) under different conditions to demonstrate that the value of a affected the gas transfer rate more than did the value of kL . High oxygen transfer rates, sufficient for supporting the high-density culture of mammalian cells, were found. Finally, the average axial velocity of the liquid was identified to be an important parameter for maintaining cells in suspension. Overall these studies provide valuable insights into the preferable operating conditions for the OSR50, such as those needed for cell cultures requiring high oxygen levels. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:192-200, 2017.

  10. Charge efficiency of Ni/H2 cells during transfer orbit of Telstar 4 satellites

    Science.gov (United States)

    Fang, W. C.; Maurer, Dean W.; Vyas, B.; Thomas, M. N.

    1994-02-01

    The TELSTAR 4 communication satellites being manufactured by Martin Marietta Astro Space (Astro Space) for AT&T are three axis stabilized spacecraft scheduled to be launched on expendable vehicles such as the Atlas or Ariane rockets. Typically, these spacecraft consist of a box that holds the electronics and supports the antenna reflectors and the solar array wings. The wings and reflectors are folded against the sides of the box during launch and the spacecraft is spun for attitude control in that phase; they are then deployed after achieving the final orbit. The launch phase and transfer orbits required to achieve the final geosynchronous orbit typically take 4 to 5 days during which time the power required for command, telemetry, attitude control, heaters, etc., is provided by two 50 AH nickel hydrogen batteries augmented by the exposed outboard solar panels. In the past, this situation has presented no problem since there was a considerable excess of power available from the array. In the case of large high powered spacecraft such as TELSTAR 4, however, the design power levels in transfer orbit approach the time-averaged power available from the exposed surface area of the solar arrays, resulting in a very tight power margin. To compound the difficulty, the array output of the spinning spacecraft in transfer orbit is shaped like a full wave rectified sine function and provides very low charging rates to the batteries during portions of the rotation. In view of the typically low charging efficiency of alkaline nickel batteries at low rates, it was decided to measure the efficiency during a simulation of the TELSTAR 4 conditions at the expected power levels and temperatures on three nickel hydrogen cells of similar design. The unique feature of nickel hydrogen cells that makes the continuous measurement of efficiency possible is that hydrogen is one of the active materials and thus, cell pressure is a direct measure of the state of charge or available capacity

  11. Orbital localization, charge transfer, and band gaps in semilocal density-functional theory.

    Science.gov (United States)

    Armiento, R; Kümmel, S

    2013-07-19

    We derive an exchange energy functional of generalized gradient form with a corresponding potential that changes discontinuously at integer particle numbers. The functional is semilocal, yet incorporates key features that are connected to the derivative discontinuity of Kohn-Sham density-functional theory. We validate our construction for several paradigm systems and explain how it addresses central well-known deficiencies of antecedent semilocal methods, i.e., the description of charge transfer, properly localized orbitals, and band gaps. We find, e.g., an improved shell structure for atoms, eigenvalues that more closely correspond to ionization energies, and an improved description of band structure where localized states are lowered in energy.

  12. Topological charge transfer in frequency doubling of fractional orbital angular momentum state

    Science.gov (United States)

    Ni, R.; Niu, Y. F.; Du, L.; Hu, X. P.; Zhang, Y.; Zhu, S. N.

    2016-10-01

    Nonlinear frequency conversion is promising for manipulating photons with orbital angular momentum (OAM). In this letter, we investigate the second harmonic generation (SHG) of light beams carrying fractional OAM. By measuring the OAM components of the generated second harmonic (SH) waves, we find that the integer components of the fundamental beam will interact with each other during the nonlinear optical process; thus, we figure out the law for topological charge transfer in frequency doubling of the fractional OAM state. Theoretical predictions by solving the nonlinear coupled wave equations are consistent with the experimental results.

  13. Explained and Unexplained Momentum Impulse Transfer Events (MITEs)

    Science.gov (United States)

    Bantel, M.; Cunio, P.; Hendrix, D.; Therien, W.

    2016-09-01

    Precision orbit determination (OD) and characterization of resident space objects (RSOs) are fundamental components of Space Situational Awareness (SSA). Over 600 days beginning January 1, 2015, ExoAnalytic Solutions collected more than 60 million correlated astrometric measurements of active and inactive resident RSOs in geosynchronous Earth orbit (GEO) and in the near-GEO region using a global network of ground-based telescopes. Orbit Determination (OD) on several inactive RSOs in sub-synchronous (e.g., spent upper stages) and super-synchronous (e.g., retired satellites) orbits revealed occasional momentum impulse transfer events (MITEs) with detectable In-track velocity changes of 0.2 to 10 mm/s. These MITEs could not be explained using the accepted gravitational model and an isotropic spherical solar radiation acceleration. Two additional radiation pressure models were considered: a Yarkovsky effect and an asymmetric radiation pressure (diffuse ellipsoid), adding one and two additional free parameters to the model, respectively. Both models include a radiation pressure component perpendicular to the solar direction and in the RSO's orbital plane. The Yarkovsky and Ellipsoid radiation pressure, in combination with the RSO traversing the Earth's Umbra, can produce a measureable change in the RSO's mean motion; a delta-v of 0.5 mm/s per season is not uncommon. OD was performed using the three radiation pressure models (Sphere, Yarkovsky, and Ellipsoid) on six inactive RSOs having 9,000 to 35,000 observations over 600 days. The Ellipsoid model was in good agreement with 95% of the observations falling within a window of ± 20 microradians, or approximately ±0.8 km, over the entire 600 day duration, which included three equinox seasons. Data collection and analysis of inactive RSOs aids the SSA mission of precision tracking and characterization of debris in the space environment.

  14. Electron-impact vibrational excitation rates in the flow field of aeroassisted orbital transfer vehicles

    Science.gov (United States)

    Lee, J.-H.

    1985-01-01

    This paper examines the vibrational excitation rate processes expected in the flow field of aeroassisted orbital transfer vehicles (AOTVs). An analysis of the multiple-quantum vibrational excitation processes by electron impact is made to predict the vibrational excitation cross sections, rate coefficients, and relaxation times which control vibrational temperature. The expression for the rate of electron-vibration energy transfer is derived by solving the system of master equations which account for the multiple-level transitions. The vibrational excitation coefficients, which are the prerequisite physical quantities in solving the obtained vibrational equation, are calculated based on the theoretically predicted cross sections. These cross sections are obtained from quantum mechanical calculations, based on the concept that vibrational excitation of molecules by electron impact occurs through formation of an intermediate negative ion state. Finally, the modified Landau-Teller-type rate equation, which is suitable for the numerical calculations for the AOTV flow fields, is suggested.

  15. Beyond frontier molecular orbital theory: a systematic electron transfer model (ETM) for polar bimolecular organic reactions.

    Science.gov (United States)

    Cahill, Katharine J; Johnson, Richard P

    2013-03-01

    Polar bimolecular reactions often begin as charge-transfer complexes and may proceed with a high degree of electron transfer character. Frontier molecular orbital (FMO) theory is predicated in part on this concept. We have developed an electron transfer model (ETM) in which we systematically transfer one electron between reactants and then use density functional methods to model the resultant radical or radical ion intermediates. Sites of higher reactivity are revealed by a composite spin density map (SDM) of odd electron character on the electron density surface, assuming that a new two-electron bond would occur preferentially at these sites. ETM correctly predicts regio- and stereoselectivity for a broad array of reactions, including Diels-Alder, dipolar and ketene cycloadditions, Birch reduction, many types of nucleophilic additions, and electrophilic addition to aromatic rings and polyenes. Conformational analysis of radical ions is often necessary to predict reaction stereochemistry. The electronic and geometric changes due to one-electron oxidation or reduction parallel the reaction coordinate for electrophilic or nucleophilic addition, respectively. The effect is more dramatic for one-electron reduction.

  16. Operationally optimal maneuver strategy for spacecraft injected into sub-geosynchronous transfer orbit

    Science.gov (United States)

    Kiran, B. S.; Singh, Satyendra; Negi, Kuldeep

    The GSAT-12 spacecraft is providing Communication services from the INSAT/GSAT system in the Indian region. The spacecraft carries 12 extended C-band transponders. GSAT-12 was launched by ISRO’s PSLV from Sriharikota, into a sub-geosynchronous Transfer Orbit (sub-GTO) of 284 x 21000 km with inclination 18 deg. This Mission successfully accomplished combined optimization of launch vehicle and satellite capabilities to maximize operational life of the s/c. This paper describes mission analysis carried out for GSAT-12 comprising launch window, orbital events study and orbit raising maneuver strategies considering various Mission operational constraints. GSAT-12 is equipped with two earth sensors (ES), three gyroscopes and digital sun sensor. The launch window was generated considering mission requirement of minimum 45 minutes of ES data for calibration of gyros with Roll-sun-pointing orientation in T.O. Since the T.O. period was a rather short 6.1 hr, required pitch biases were worked out to meet the gyro-calibration requirement. A 440 N Liquid Apogee Motor (LAM) is used for orbit raising. The objective of the maneuver strategy is to achieve desired drift orbit satisfying mission constraints and minimizing propellant expenditure. In case of sub-GTO, the optimal strategy is to first perform an in-plane maneuver at perigee to raise the apogee to synchronous level and then perform combined maneuvers at the synchronous apogee to achieve desired drift orbit. The perigee burn opportunities were examined considering ground station visibility requirement for monitoring the burn. Two maneuver strategies were proposed: an optimal five-burn strategy with two perigee burns centered around perigee#5 and perigee#8 with partial ground station visibility and three apogee burns with dual station visibility, a near-optimal five-burn strategy with two off-perigee burns at perigee#5 and perigee#8 with single ground station visibility and three apogee burns with dual station visibility

  17. Influence of radiant energy exchange on the determination of convective heat transfer rates to Orbiter leeside surfaces during entry

    Science.gov (United States)

    Throckmorton, D. A.

    1982-01-01

    Temperatures measured at the aerodynamic surface of the Orbiter's thermal protection system (TPS), and calorimeter measurements, are used to determine heating rates to the TPS surface during atmospheric entry. On the Orbiter leeside, where convective heating rates are low, it is possible that a significant portion of the total energy input may result from solar radiation, and for the wing, cross radiation from the hot (relatively) Orbiter fuselage. In order to account for the potential impact of these sources, values of solar- and cross-radiation heat transfer are computed, based upon vehicle trajectory and attitude information and measured surface temperatures. Leeside heat-transfer data from the STS-2 mission are presented, and the significance of solar radiation and fuselage-to-wing cross-radiation contributions to total energy input to Orbiter leeside surfaces is assessed.

  18. Lab tests of a thermomechanical pump for shoot. [Superfluid Helium On-Orbit Transfer

    Science.gov (United States)

    Dipirro, Michael J.; Boyle, Robert F.

    1988-01-01

    Laboratory tests of a thermomechanical (TM) pump utilizing a commercially available porous disk have been conducted. Various size disks, heater configurations, and outlet flow impedances have been used to characterize scale models of the pump proposed for the Superfluid Helium On-Orbit Transfer (SHOOT) Flight Experiment. The results yield the scalability of the TM pump to larger diameters, and hence larger pumping rates, the dependence of flow rate on back pressure and heater power, and the limits of pumping speed due to internal losses within the porous disk due to mutual and superfluid friction. Analysis indicates that for low back pressures the flow rate is limited by the superfluid friction rather than the mutual friction. For the porous plug used in the early tests this amounts to a practical limit of 4.4 liters per hour per square centimeter. For a baselined flight plug area of 180 sq cm this yields 790 liters per hour.

  19. Solution accuracies of finite element reentry heat transfer and thermal stress analyses of Space Shuttle Orbiter

    Science.gov (United States)

    Ko, William L.

    1988-01-01

    Accuracies of solutions (structural temperatures and thermal stresses) obtained from different thermal and structural FEMs set up for the Space Shuttle Orbiter (SSO) are compared and discussed. For studying the effect of element size on the solution accuracies of heat-transfer and thermal-stress analyses of the SSO, five SPAR thermal models and five NASTRAN structural models were set up for wing midspan bay 3. The structural temperature distribution over the wing skin (lower and upper) surface of one bay was dome shaped and induced more severe thermal stresses in the chordwise direction than in the spanwise direction. The induced thermal stresses were extremely sensitive to slight variation in structural temperature distributions. Both internal convention and internal radiation were found to have equal effects on the SSO.

  20. Atmospheric Mining in the Outer Solar System: Outer Planet Orbital Transfer and Lander Analyses

    Science.gov (United States)

    Palaszewski, Bryan

    2016-01-01

    Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. Analyses of orbital transfer vehicles (OTVs), landers, and the issues with in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. For analyses of round trip OTV flights from Uranus to Miranda or Titania, a 10- Megawatt electric (MWe) OTV power level and a 200 metricton (MT) lander payload were selected based on a relative short OTV trip time and minimization of the number of lander flights. A similar optimum power level is suggested for OTVs flying from low orbit around Neptune to Thalassa or Triton. Several moon base sites at Uranus and Neptune and the OTV requirements to support them are also addressed.

  1. Transfer orbits to L4 with a solar sail in the Earth-Sun system

    Science.gov (United States)

    Farrés, Ariadna

    2017-08-01

    Solar sails are enablers for long interplanetary transfers, but also offer many advantages in Libration Point Orbits missions. The extra effect of the Solar Radiation Pressure allows a space vehicle, by changing the sail orientation, to be artificially displaced from the classical Lagrangian equilibrium points, L1 , … ,L5 , as well perturbed from the Lyapunov, Halo and Lissajous orbits that appear around them. Most of these equilibrium points are linearly unstable and have stable and unstable invariant manifolds associated with them. In this paper we explore the possibilities that these invariant manifolds offer to navigate in a natural way around a circular, restricted, three-body system. We take the Earth-Sun Restricted Three Body Problem as a model and, for different fixed sail orientations, we compute the stable and unstable manifolds associated with the equilibrium points of the system. We find natural trajectories that allow the vehicle to move around the family of equilibria in a controlled way and to go from a region close to L1 or L2 to a region close to L4.

  2. Superfluid helium orbital resupply - The status of the SHOOT flight experiment and preliminary user requirements. [Superfluid Helium On-Orbit Transfer

    Science.gov (United States)

    Dipirro, Michael J.; Kittel, Peter

    1989-01-01

    The Superfluid Helium On-Orbit Transfer (SHOOT) flight experiment is designed to demonstrate the components and techniques necessary to resupply superfluid helium to satellites or Space Station based facilities. A top level description as well as the development status of the critical components to be used in SHOOT are discussed. Some of these components include the thermomechanical pump, the fluid acquisition system, the normal helium and superfluid helium phase separators, Venturi flow meter, cryogenic valves, burst disks, and astronaut-compatible EVA coupler and transfer line. The requirements for the control electronics and software are given. A preliminary description of the requirements that must be met by a satellite requiring superfluid helium servicing is given. In particular, minimum and optimum plumbing arrangements are shown, transfer line flow impedance and heat input impacts are assessed, instrumentation is described, and performance parameters are considered.

  3. A First-Order Analytical Theory for Optimal Low-Thrust Limited-Power Transfers between Arbitrary Elliptical Coplanar Orbits

    Directory of Open Access Journals (Sweden)

    Sandro da Silva Fernandes

    2008-01-01

    Full Text Available A complete first-order analytical solution, which includes the short periodic terms, for the problem of optimal low-thrust limited-power transfers between arbitrary elliptic coplanar orbits in a Newtonian central gravity field is obtained through canonical transformation theory. The optimization problem is formulated as a Mayer problem of optimal control theory with Cartesian elements—position and velocity vectors—as state variables. After applying the Pontryagin maximum principle and determining the maximum Hamiltonian, classical orbital elements are introduced through a Mathieu transformation. The short periodic terms are then eliminated from the maximum Hamiltonian through an infinitesimal canonical transformation built through Hori method. Closed-form analytical solutions are obtained for the average canonical system by solving the Hamilton-Jacobi equation through separation of variables technique. For transfers between close orbits a simplified solution is straightforwardly derived by linearizing the new Hamiltonian and the generating function obtained through Hori method.

  4. Magnetization reversal in ferromagnetic thin films induced by spin-orbit interaction with Slonczewski-like spin transfer torque

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jia, E-mail: lijia@wipm.ac.cn [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)

    2014-10-07

    We theoretically investigate the dynamics of magnetization in ferromagnetic thin films induced by spin-orbit interaction with Slonczewski-like spin transfer torque. We reproduce the experimental results of perpendicular magnetic anisotropy films by micromagnetic simulation. Due to the spin-orbit interaction, the magnetization can be switched by changing the direction of the current with the assistant of magnetic field. By increasing the current amplitude, wider range of switching events can be achieved. Time evolution of magnetization has provided us a clear view of the process, and explained the role of minimum external field. Slonczewski-like spin transfer torque modifies the magnetization when current is present. The magnitude of the minimum external field is determined by the strength of the Slonczewski-like spin transfer torque. The investigations may provide potential applications in magnetic memories.

  5. Integrated control and health management. Orbit transfer rocket engine technology program

    Science.gov (United States)

    Holzmann, Wilfried A.; Hayden, Warren R.

    1988-01-01

    To insure controllability of the baseline design for a 7500 pound thrust, 10:1 throttleable, dual expanded cycle, Hydrogen-Oxygen, orbit transfer rocket engine, an Integrated Controls and Health Monitoring concept was developed. This included: (1) Dynamic engine simulations using a TUTSIM derived computer code; (2) analysis of various control methods; (3) Failure Modes Analysis to identify critical sensors; (4) Survey of applicable sensors technology; and, (5) Study of Health Monitoring philosophies. The engine design was found to be controllable over the full throttling range by using 13 valves, including an oxygen turbine bypass valve to control mixture ratio, and a hydrogen turbine bypass valve, used in conjunction with the oxygen bypass to control thrust. Classic feedback control methods are proposed along with specific requirements for valves, sensors, and the controller. Expanding on the control system, a Health Monitoring system is proposed including suggested computing methods and the following recommended sensors: (1) Fiber optic and silicon bearing deflectometers; (2) Capacitive shaft displacement sensors; and (3) Hot spot thermocouple arrays. Further work is needed to refine and verify the dynamic simulations and control algorithms, to advance sensor capabilities, and to develop the Health Monitoring computational methods.

  6. Improvement of orbit determination accuracy for Beidou Navigation Satellite System with Two-way Satellite Time Frequency Transfer

    Science.gov (United States)

    Tang, Chengpan; Hu, Xiaogong; Zhou, Shanshi; Guo, Rui; He, Feng; Liu, Li; Zhu, Lingfeng; Li, Xiaojie; Wu, Shan; Zhao, Gang; Yu, Yang; Cao, Yueling

    2016-10-01

    The Beidou Navigation Satellite System (BDS) manages to estimate simultaneously the orbits and clock offsets of navigation satellites, using code and carrier phase measurements of a regional network within China. The satellite clock offsets are also directly measured with Two-way Satellite Time Frequency Transfer (TWSTFT). Satellite laser ranging (SLR) residuals and comparisons with the precise ephemeris indicate that the radial error of GEO satellites is much larger than that of IGSO and MEO satellites and that the BDS orbit accuracy is worse than GPS. In order to improve the orbit determination accuracy for BDS, a new orbit determination strategy is proposed, in which the satellite clock measurements from TWSTFT are fixed as known values, and only the orbits of the satellites are solved. However, a constant systematic error at the nanosecond level can be found in the clock measurements, which is obtained and then corrected by differencing the clock measurements and the clock estimates from orbit determination. The effectiveness of the new strategy is verified by a GPS regional network orbit determination experiment. With the IGS final clock products fixed, the orbit determination and prediction accuracy for GPS satellites improve by more than 50% and the 12-h prediction User Range Error (URE) is better than 0.12 m. By processing a 25-day of measurement from the BDS regional network, an optimal strategy for the satellite-clock-fixed orbit determination is identified. User Equivalent Ranging Error is reduced by 27.6% for GEO satellites, but no apparent reduction is found for IGSO/MEO satellites. The SLR residuals exhibit reductions by 59% and 32% for IGSO satellites but no reductions for GEO and MEO satellites.

  7. Energy loss spectroscopy of Buckminster C60 with twisted electrons: Influence of orbital angular momentum transfer on plasmon generation

    CERN Document Server

    Schüler, M

    2016-01-01

    Recent experimental progress in creating and controlling singular electron beams that carry orbital angular momentum allows for new types of local spectroscopies. We theoretically investigate the twisted-electron energy loss spectroscopy (EELS) from the C60 fullerene. Of particular interest are the strong multipolar collective excitations and their selective response to the orbital angular momentum of the impinging electron beam. Based on ab-initio calculations for the collective response we compute EELS signals with twisted electron beams and uncover the interplay between the plasmon polarity and the amount of angular momentum transfer.

  8. Charge-transfer (CT) orbitals for the one-electron description of CT excitations in a wide range of donor-acceptor separations

    Science.gov (United States)

    Gritsenko, O. V.

    2017-01-01

    A transformation of the virtual Kohn-Sham orbitals is proposed to a set of charge-transfer orbitals (CTOs) adapted to description of CT excitations. The CTO scheme offers a simple estimate of the CT excitation energy with an orbital energy difference. This estimate reproduces well the reference values of the configuration interaction (CI) method in a wide range of donor-acceptor separations in the paradigmatic He -Be complex. CTO-based orbital energy and shape indices are proposed to assess the suitability of the CT description with virtual orbitals of a given basis set. Both indices yield correct trends for the Kohn-Sham and Hartree-Fock orbitals.

  9. The Earth-Moon CR3BP: A full Atlas of low-energy fast periodic transfer orbits

    CERN Document Server

    Leiva, A M; Leiva, Alejandro M.; Briozzo, Carlos B.

    2006-01-01

    In the framework of the planar CR3BP for mass parameter mu=0.0121505, corresponding to the Earth-Moon system, we identify and describe 80 families of periodic orbits encircling both the Earth and the Moon ("transfer" orbits). All the orbits in these families have very low energies, most of them corresponding to values of the Jacobi constant C for which the Hill surface is closed at the Lagrangian point L2. All of these orbits have also short period T, generally under six months. Most of the families are composed of orbits that are asymmetric with respect to the Earth-Moon axis. The main results presented for each family are: (i) the characteristic curves T(h), y(h), v_y(h), and v_x(h) on the Poincare section Sigma_1={x=0.836915310,y,v_x>0,v_y} normal to the Earth-Moon axis at the Lagrangian point L1, parameterized by their energy h=-C/2 in the synodic coordinate system; (ii) the stability parameter along each family; (iii) the intersections x_i(h) of the orbits with the Earth-Moon axis, on the Poincare sectio...

  10. Experimental verification of orbital engineering at the atomic scale: Charge transfer and symmetry breaking in nickelate heterostructures

    Science.gov (United States)

    Phillips, Patrick J.; Rui, Xue; Georgescu, Alexandru B.; Disa, Ankit S.; Longo, Paolo; Okunishi, Eiji; Walker, Fred; Ahn, Charles H.; Ismail-Beigi, Sohrab; Klie, Robert F.

    2017-05-01

    Epitaxial strain, layer confinement, and inversion symmetry breaking have emerged as powerful new approaches to control the electronic and atomic-scale structural properties of complex metal oxides. Trivalent rare-earth (RE) nickelate R E NiO3 heterostructures have been shown to be exemplars since the orbital occupancy, degeneracy, and, consequently, electronic/magnetic properties can be altered as a function of epitaxial strain, layer thickness, and superlattice structure. One recent example is the tricomponent LaTiO3-LaNiO3-LaAlO3 superlattice which exhibits charge transfer and orbital polarization as the result of its interfacial dipole electric field. A crucial step towards control of these parameters for future electronic and magnetic device applications is to develop an understanding of both the magnitude and range of the octahedral network's response towards interfacial strain and electric fields. An approach that provides atomic-scale resolution and sensitivity towards the local octahedral distortions and orbital occupancy is therefore required. Here, we employ atomic-resolution imaging coupled with electron spectroscopies and first-principles theory to examine the role of interfacial charge transfer and symmetry breaking in a tricomponent nickelate superlattice system. We find that nearly complete charge transfer occurs between the LaTiO3 and LaNiO3 layers, resulting in a mixed Ni2 +/Ni3 + valence state. We further demonstrate that this charge transfer is highly localized with a range of about 1 unit cell within the LaNiO3 layers. We also show how Wannier-function-based electron counting provides a simple physical picture of the electron distribution that connects directly with formal valence charges. The results presented here provide important feedback to synthesis efforts aimed at stabilizing new electronic phases that are not accessible by conventional bulk or epitaxial film approaches.

  11. Spectroscopic studies and molecular orbital calculations of charge transfer complexation between 3,5-dimethylpyrazole with DDQ in acetonitrile.

    Science.gov (United States)

    Habeeb, Moustafa M; Al-Attas, Amirah S; Al-Raimi, Doaa S

    2015-05-05

    Charge transfer (CT) interaction between 3,5-dimethylpyrazole (DMP) with the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinon (DDQ) has been investigated spectrophotometrically in acetonitrile (AN). Simultaneous reddish brown color has been observed upon mixing donor with acceptor solutions attributing to CT complex formation. The electronic spectra of the formed complex exhibited multi-charge transfer bands at 429, 447, 506, 542 and 589nm, respectively. Job(')s method of continuous variations and spectrophotometric titration methods confirmed the formation of the studied complex in 1:2 ratio between DMP and DDQ. Benesi-Hildebrand equation has been applied to calculate the stability constant of the formed complex where it recorded high value supporting formation of stable complex. Molecular orbital calculations using MM2 method and GAMESS (General Atomic and Molecular Electronic Structure System) interface computations as a package of ChemBio3D Ultra12 software were carried out for more analysis of the formed complex in the gas phase. The computational analysis included energy minimisation, stabilisation energy, molecular geometry, Mullikan charges, molecular electrostatic potential (MEP) surfaces of reactants and complex as well as characterization of the higher occupied molecular orbitals (HOMO) and lower unoccupied molecular orbitals (LUMO) surfaces of the complex. A good consistency between experimental and theoretical results has been recorded.

  12. Electronic structure of novel charge transfer compounds: application of Fermi orbital self-interaction corrected density functional theory

    Science.gov (United States)

    Hahn, Torsten; Rückerl, Florian; Liebing, Simon; Pederson, Mark

    We present our experimental and theoretical results on novel Picene/F4TCNQ and Manganese-Phthalocyanine/F4TCNQ donor / acceptor systems. We apply the recently developed Fermi-orbital based approach for self-interaction corrected density functional theory (FO-SIC DFT) to these materials and compare the results to standard DFT calculations and to experimental data obtained by photoemission spectroscopy. We focus our analysis on the description of the magnitude of the ground state charge transfer and on the details of the formed hybrid orbitals. Further, we show that for weakly bound donor / acceptor systems the FO-SIC approach delivers a more realistic description of the electronic structure compared to standard DFT calculations Support by DFG FOR1154 is greatly acknowledged.

  13. Low gravity thermal stratification of liquid helium on SHOOT. [Superfluid Helium On-Orbit Transfer

    Science.gov (United States)

    Shirron, P. J.; Dipirro, M. J.

    1992-01-01

    Estimates of the extent and impact of thermal stratification are presented as well as predictions of the behavior of the HeI/HeII boundary. Although thermal stratification of cryogens can be problematic and lead to their inefficient use in low gravity, for SHOOT the occurrence is beneficial both during ground hold and in orbit and presents no hazards. On the ground the parasitic heat load is both reduced and more efficiently removed. In orbit the pumpdown proceeds at a much more rapid rate, allowing orbital operations to begin earlier. The thermal conductivity of the aluminum tank and the normal liquid plus cooling at the liquid/vapor interface as the vapor bubble grows are sufficient to prevent undesirably high vapor pressures in the tank.

  14. NASA's CSTI Earth-to-Orbit Propulsion Program - On-target technology transfer to advanced space flight programs

    Science.gov (United States)

    Escher, William J. D.; Herr, Paul N.; Stephenson, Frank W., Jr.

    1990-01-01

    NASA's Civil Space Technology Initiative encompasses among its major elements the Earth-to-Orbit Propulsion Program (ETOPP) for future launch vehicles, which is budgeted to the extent of $20-30 million/year for the development of essential technologies. ETOPP technologies include, in addition to advanced materials and processes and design/analysis computational tools, the advanced systems-synthesis technologies required for definition of highly reliable LH2 and hydrocarbon fueled rocket engines to be operated at significantly reduced levels of risk and cost relative to the SSME. Attention is given to the technology-transfer services of ETOPP.

  15. Numerical and Analytical Study of Optimal Low-Thrust Limited-Power Transfers between Close Circular Coplanar Orbits

    Directory of Open Access Journals (Sweden)

    Sandro da Silva Fernandes

    2007-01-01

    Full Text Available A numerical and analytical study of optimal low-thrust limited-power trajectories for simple transfer (no rendezvous between close circular coplanar orbits in an inverse-square force field is presented. The numerical study is carried out by means of an indirect approach of the optimization problem in which the two-point boundary value problem, obtained from the set of necessary conditions describing the optimal solutions, is solved through a neighboring extremal algorithm based on the solution of the linearized two-point boundary value problem through Riccati transformation. The analytical study is provided by a linear theory which is expressed in terms of nonsingular elements and is determined through the canonical transformation theory. The fuel consumption is taken as the performance criterion and the analysis is carried out considering various radius ratios and transfer durations. The results are compared to the ones provided by a numerical method based on gradient techniques.

  16. 地球静止轨道—低轨道最优异面转移方法%Optimal noncoplanar orbital transfer between GEO and low-earth orbit

    Institute of Scientific and Technical Information of China (English)

    符俊; 蔡洪; 丁智坚

    2012-01-01

    研究了轨道转移飞行器(orbital transfer vehicle,OTV)从地球静止轨道向低轨道的最优异面转移过程,提出了解析法和智能优化算法.在解析法中,完整地推导了最优转移轨道的求解方法,提出了最优转移轨道应满足的条件,并采用牛顿迭代法求解第1次速度脉冲应改变的轨道倾角.以离轨点位置、入轨点位置和转移时间为优化变量,采用遗传算法对最优转移过程进行求解,给出了遗传算法求解该优化问题的设计步骤,并将变轨过程在卫星工具包(satellite tool kit,STK)场景中进行了演示.仿真结果表明两种方法均能满足Lawden一阶最优必要条件.%The optimal noncoplanar orbital transfer between geostationary earth orbit (GEO) and low-earth orbit for the orbital transfer vehicle (OTV) is studied,and analytical method and intelligence optimization algorithm are proposed.For the analytical method,the solution of the optimal transfer orbit is fully derived.The conditions which the optimal transfer orbit should be satisfied are given,and the optimal changed inclination due to the first impulse is solved by Newton iteration.The genetic algorithm (GA) is used to solve the optimal transfer orbit,where the optimal solution is composed of deorbit position,reorbit position and transfer time.The steps for GA are given and the demo of orbital transfer is carried out in Satellite Tool Kit (STK).The simulation results show that the Lawden's first-order optimality condition can be satisfied for both methods.

  17. Analytical Equations for Orbital Transfer Maneuvers of a Vehicle Using Constant Low Thrust

    Science.gov (United States)

    1981-12-01

    136auks" ,b , .. .. a. AFIT/GA/AA/81D -3 ANALITICAL EQUATIOIS FOR OR.BITAL TRASFER MANIUVRS OF A V 1CI, USING CONSTANT LOW THRUST THESIS AFIT/GA/AA...conventional chemical propulsion system- (Ref 1). Changing the velocity of a satellite such as described above can be used to boost a satellite into...taneously. This is a valid assumption for high thrust chemical propulsion, but not for low thrust electric propulsion. Therefore, a set of equations

  18. Evidence of Charge Transfer and Orbital Magnetic Moment in Multiferroic CuFeO2

    Science.gov (United States)

    Narumi, Yasuo; Nakamura, Tetsuya; Ikeno, Hidekazu; Terada, Noriki; Morioka, Takayuki; Saito, Kota; Kitazawa, Hideaki; Kindo, Koichi; Nojiri, Hiroyuki

    2016-11-01

    Soft X-ray absorption spectra (XAS) and magnetic circular dichroism (XMCD) of Fe and Cu L2,3 edges have been measured on the triangular lattice antiferromagnet CuFeO2. By applying sum rule analysis to the XMCD of Fe, the ratio of the orbital to spin magnetic moments is determined to be -0.071. Because the nominal valence of Fe in CuFeO2 was Fe3+ (3d5), the orbital magnetic moment was considered to be zero in the past. However, the present research demonstrates that the orbital magnetic moment of Fe takes a finite value and it is possibly due to Fe4+ (3d4), which is considered to be responsible for the strong magnetic anisotropy and the ferroelectricity. We compare the experimental results with the results of ab initio multiplet calculations based on the configuration interaction theory and discuss the anomalous electronic structures of Fe and Cu ions in CuFeO2.

  19. An Integrated Approach to Modeling Solar Electric Propulsion Vehicles During Long Duration, Near-Earth Orbit Transfers

    Science.gov (United States)

    Smith, David A.; Hojnicki, Jeffrey S.; Sjauw, Waldy K.

    2014-01-01

    Recent NASA interest in utilizing solar electronic propulsion (SEP) technology to transfer payloads, e.g. from low-Earth orbit (LEO) to higher energy geostationary-Earth orbit (GEO) or to Earth escape, has necessitated the development of high fidelity SEP vehicle models and simulations. These models and simulations need to be capable of capturing vehicle dynamics and sub-system interactions experienced during the transfer trajectories which are typically accomplished with continuous-burn (potentially interrupted by solar eclipse), long duration "spiral out" maneuvers taking several months or more to complete. This paper presents details of an integrated simulation approach achieved by combining a high fidelity vehicle simulation code with a detailed solar array model. The combined simulation tool gives researchers the functionality to study the integrated effects of various vehicle sub-systems (e.g. vehicle guidance, navigation and control (GN&C), electric propulsion system (EP)) with time varying power production. Results from a simulation model of a vehicle with a 50 kW class SEP system using the integrated tool are presented and compared to the results from another simulation model employing a 50 kW end-of-life (EOL) fixed power level assumption. These models simulate a vehicle under three degree of freedom dynamics (i.e. translational dynamics only) and include the effects of a targeting guidance algorithm (providing a "near optimal" transfer) during a LEO to near Earth escape (C (sub 3) = -2.0 km (sup 2) / sec (sup -2) spiral trajectory. The presented results include the impact of the fully integrated, time-varying solar array model (e.g. cumulative array degradation from traversing the Van Allen belts, impact of solar eclipses on the vehicle and the related temperature responses in the solar arrays due to operating in the Earth's thermal environment, high fidelity array power module, etc.); these are used to assess the impact on vehicle performance (i

  20. Orbital transfers in an asteroid system considering the solar radiation pressure

    Science.gov (United States)

    Oliveira, Geraldo Magela Couto; Bertachini de A. Prado, Antonio F.; Sanchez, Diogo Merguizo; Gomes, Vivian Martins

    2017-10-01

    The present paper studies the effects of the radiation pressure in the trajectories of a spacecraft in transfers between the collinear Lagrange points of a double asteroid system. The system considered is this paper is formed by the double asteroid 1996FG3 and the maneuvers are always assumed to be bi-impulsive. In a system formed by asteroids, the solar radiation pressure has a significant influence in the transfers paths. This occurs because the gravitational forces in these systems are smaller if compared with systems formed by larger bodies. Solutions with lower and higher fuel consumption can be found by adding the solar radiation pressure. The radiation pressure was not used as a control but its effects over the transfers were measured. For a small system of primaries such as an asteroid system, it is very important to take into account this force to make sure that the spacecraft will reach the desired point.

  1. Coherent transfer of optical orbital angular momentum in multi-order Raman sideband generation

    CERN Document Server

    Strohaber, J; Sokolov, A V; Kolomenskii, A A; Paulus, G G; Schuessler, H A

    2012-01-01

    Experimental results from the generation of Raman sidebands using optical vortices are presented. By generating two sets of sidebands originating from different locations in a Raman active crystal, one set containing optical orbital angular momentum and the other serving as a reference, a Young's double slit experiment was simultaneously realized for each sideband. The interference between the two sets of sidebands was used to determine the helicity and topological charge in each order. Topological charges in all orders were found to be discrete and follow selection rules predicted by a cascaded Raman process.

  2. Coherent transfer of optical orbital angular momentum in multi-order Raman sideband generation.

    Science.gov (United States)

    Strohaber, J; Zhi, M; Sokolov, A V; Kolomenskii, A A; Paulus, G G; Schuessler, H A

    2012-08-15

    Experimental results from the generation of Raman sidebands using optical vortices are presented. By generating two sets of sidebands originating from different locations in a Raman-active crystal, one set containing optical orbital angular momentum and the other serving as a reference, Young's double slit experiment was simultaneously realized for each sideband. The interference between the two sets of sidebands was used to determine the helicity and topological charge in each order. Topological charges in all orders were found to be discrete and follow selection rules predicted by a cascaded Raman process.

  3. Orbital angular momentum (OAM) multiplexing in free-space optical data transfer

    Science.gov (United States)

    Lin, Jiao; Yuan, Xiao-Cong; Tao, Shaohua

    2006-08-01

    In the optical wireless communication systems proposed by Gibson, et al, the information is encoded as states of orbital angular momentum (OAM) of light and the transmitter unit can produce laser beam with single OAM-state in a time-slot. Recently we have proved that it is possible to generate multiple OAM-states simultaneously by single spatial light modulator. This method is adopted in our free-space optical wireless communication system and these OAM-states can be detected in the receiving unit by a computer-generated hologram. Hence, the transmission capacity is enhanced significantly without increasing the complexity of system.

  4. Molecular orbital (SCF-Xα-SW) theory of metal-metal charge transfer processes in minerals

    Science.gov (United States)

    Sherman, David M.

    1987-01-01

    A number of mixed valence iron oxides and silicates (e.g., magnetite, ilvaite) exhibit thermally induced electron delocalization between adjacent Fe2+ and Fe3+ ions and optically induced electronic transitions which are assigned to Fe2+→Fe3+ intervalence charge transfer.

  5. Feedback Optimal Control of Low-thrust Orbit Transfer in Central Gravity Field

    Directory of Open Access Journals (Sweden)

    Ashraf H. Owis

    2013-05-01

    Full Text Available Low-thrust trajectories with variable radial thrust is studied in this paper. The problem is tackled by solving the Hamilton- Jacobi-Bellman equation via State Dependent Riccati Equation( STDE technique devised for nonlinear systems. Instead of solving the two-point boundary value problem in which the classical optimal control is stated, this technique allows us to derive closed-loop solutions. The idea of the work consists in factorizing the original nonlinear dynamical system into a quasi-linear state dependent system of ordinary differential equations. The generating function technique is then applied to this new dynamical system, the feedback optimal control is solved. We circumvent in this way the problem of expanding the vector field and truncating higher-order terms because no remainders are lost in the undertaken approach. This technique can be applied to any planet-to-planet transfer; it has been applied here to the Earth-Mars low-thrust transfer

  6. Cryogenic and thermal design for the Superfluid Helium On-Orbit Transfer (SHOOT) experiment

    Science.gov (United States)

    Lee, J. H.; Maa, S.; Brooks, W. F.; Ng, Y. S.

    1988-01-01

    The analysis and trade-offs of the external thermal design of the two 200-liter dewars required in the SHOOT experiment to extend space mission life by superfluid helium replenishment are discussed. Also considered are the support electronics and the optimization and prediction of the performance of the dewar and cryostat assemblies. Particular attention is given to the ground-hold and standby performance of the dewars, along with the temperature of the helium bath during high-flow-rate helium transfers.

  7. Orbital Interaction and Electron Density Transfer in PdII([9]aneB2AL2 Complexes: Theoretical Approaches

    Directory of Open Access Journals (Sweden)

    Jong Keun Park

    2013-10-01

    Full Text Available The geometric structures of Pd-complexes {Pd([9]aneB2AL2 and Pd([9]aneBABL2 where A = P, S; B = N; L = PH3, P(CH33, Cl−}, their selective orbital interaction towards equatorial or axial (soft A…Pd coordination of macrocyclic [9]aneB2A tridentate to PdL2, and electron density transfer from the electron-rich trans L-ligand to the low-lying unfilled a1g(5s-orbital of PdL2 were investigated using B3P86/lanl2DZ for Pd and 6-311+G** for other atoms. The pentacoordinate endo-[Pd([9]aneB2A(L-donor2]2+ complex with an axial (soft A--Pd quasi-bond was optimized for stability. The fifth (soft A--Pd quasi-bond between the σ-donor of soft A and the partially unfilled a1g(5s-orbital of PdL2 was formed. The pentacoordinate endo-Pd([9]aneB2A(L-donor2]2+ complex has been found to be more stable than the corresponding tetracoordinate endo-Pd complexes. Except for the endo-Pd pentacoordinates, the tetracoordinate Pd([9]aneBABL2 complex with one equatorial (soft A-Pd bond is found to be more stable than the Pd([9]aneB2AL2 isomer without the equatorial (A-Pd bond. In particular, the geometric configuration of endo-[Pd([9]anePNP(L-donor2]2+ could not be optimized.

  8. Measurements of the linear energy transfer spectra on the Mir orbital station and comparison with radiation transport models

    Science.gov (United States)

    Badhwar, G. D.; Konradi, A.; Atwell, W.; Golightly, M. J.; Cucinotta, F. A.; Wilson, J. W.; Petrov, V. M.; Tchernykh, I. V.; Shurshakov, V. A.; Lobakov, A. P.

    1996-01-01

    A tissue equivalent proportional counter designed to measure the linear energy transfer spectra (LET) in the range 0.2-1250 keV/micrometer was flown in the Kvant module on the Mir orbital station during September 1994. The spacecraft was in a 51.65 degrees inclination, elliptical (390 x 402 km) orbit. This is nearly the lower limit of its flight altitude. The total absorbed dose rate measured was 411.3 +/- 4.41 microGy/day with an average quality factor of 2.44. The galactic cosmic radiation (GCR) dose rate was 133.6 microGy/day with a quality factor of 3.35. The trapped radiation belt dose rate was 277.7 microGy/day with an average quality factor of 1.94. The peak rate through the South Atlantic Anomaly was approximately 12 microGy/min and nearly constant from one pass to another. A detailed comparison of the measured LET spectra has been made with radiation transport models. The GCR results are in good agreement with model calculations; however, this is not the case for radiation belt particles and again points to the need for improving the AP8 omni-directional trapped proton models.

  9. Spatial statistical point prediction guidance for heating-rate-limited aeroassisted orbital transfer

    Science.gov (United States)

    Ghosh, Pradipto; Conway, Bruce A.

    2015-06-01

    Feedback control of constrained non-linear dynamical systems satisfying a certain optimality criterion and meeting a specified transfer objective in the state space is recognized as one of the most challenging problems in control theory. One approach to computing optimal feedback policies is the dynamic programming route of numerically solving the Hamilton-Jacobi-Bellman (HJB) partial differential equation directly. In this paper an alternate and more tractable dynamic programming approach, the optimal feedback synthesis method, is utilized. The effectiveness of this method is demonstrated through an explicit guidance scheme for the heating-rate-constrained maneuver of an Aeroassisted Transfer Vehicle (AOTV). In optimal feedback synthesis, a feedback chart is constructed from a family of open-loop extremals, thus ensuring optimality with respect to any initial condition in the family. This paper presents a solution to the AOTV optimal feedback synthesis problem using the Gaussian process spatial prediction method of universal kriging. A closed-form expression for a near-optimal guidance law is derived. Its performance is found to be very promising; initial atmospheric entry errors due to simulated thruster misfiring are seen to be accurately corrected while the algebraic state-inequality constraint is closely respected.

  10. Spin-orbit evolution of Mercury revisited

    CERN Document Server

    Noyelles, Benoit; Makarov, Valeri; Efroimsky, Michael

    2013-01-01

    Mercury is a peculiar case, in that it is locked into the 3:2 spin-orbit resonance. Its rotation period, 58 days, is exactly two thirds of its orbital period. It is accepted that the eccentricity of Mercury (0.206) favours the trapping into this resonance. More controversial is how the capture took place. A recent study by Makarov has shown that entrapment into this resonance is certain if the eccentricity is larger than 0.2, provided that we use a realistic tidal model, based on the Darwin-Kaula expansion of the tidal torque, including both the elastic rebound and anelastic creep of solids. We here revisit the scenario of Mercury's capture into the supersynchronous spin-orbit resonances. The study is based on a realistic model of tidal friction in solids, that takes into account the rheology and the self-gravitation of the planet. Developed in Efroimsky, it was employed by Makarov et al. to determine the likely spin state of the planet GJ581d, with its eccentricity evolution taken into account. It was also u...

  11. Cost curves for the navigation between families of low energy Fast Periodic Transfer Orbits in the Earth-Moon planar circular restricted Three Body Problem.

    Science.gov (United States)

    Marcuzzi, J. P.; Leiva, A. M.; Briozzo, C. B.

    Using characteristic curves of low energy fast periodic transfer orbits in the Earth-Moon planar circular restricted three body problem we constructed cost curves that enable the study of maneuvers between them. In an appropiate surface of section the numerical diagrams show regions where transfer maneuvers involve lower costs and that would allow determine family members which make the propelent minimum for these maneuvers. FULL TEXT IN SPANISH.

  12. Surprising microscopy subtleties: Measuring picoscale thicknesses, visualizing core orbitals, and detecting charge transfer using the TEM

    Science.gov (United States)

    Odlyzko, Michael Luke

    50 years ago, Richard Feynman delivered a now-famous address outlining why there was "plenty of room left at the bottom": there remained much progress to be made in seeing and manipulating matter all the way down to the atomic scale. One of many means to that end, argued Feynman, was to make electron microscopes better. Why could not electrons with wavelengths of a few picometers not be used to clearly image atoms hundreds of picometers in size? Why could not electron beams be used to pattern miniscule wires a handful of metal atoms across? Over the course of decades, Feynman's vision has been pursued zealously with rich reward, not least in the electron microscopy field. Enabled by the development of bright field-emission electron sources, high-resolution polepieces, and now aberration correctors, transmission electron microscopy (TEM) at atomic resolution has become routine. Seemingly, there is little room left at the bottom; after all, once you can clearly see atoms, what more is there left to do? Thankfully, there is plenty. Much of the hard work has been in the development of equipment that expands TEM to allow unprecedented spatially resolved analysis of elemental composition, inelastic scattering, and temporal processes. But there are also many opportunities to uncover new information using now widely available techniques and equipment. In the studies presented here, there has been some success in following the latter path. In tandem with careful computational analysis, selected-area electron diffraction allows not only determination of crystal symmetry, lattice parameter, and microstructure, but also measurements of material thickness on the scale of atomic layers. Supported by careful data processing and rigorous simulations, spatially resolved X-ray spectroscopy data is converted into real-space measurements of core-level electronic orbitals, in addition to providing routine atomic resolution chemical mapping. And aided by the development of novel bonding

  13. Charge transfer and polarization for chloride ions bound in ClC transport proteins: natural bond orbital and energy decomposition analyses.

    Science.gov (United States)

    Church, Jonathan; Pezeshki, Soroosh; Davis, Christal; Lin, Hai

    2013-12-19

    ClC transport proteins show a distinct "broken-helix" architecture, in which certain α-helices are oriented with their N-terminal ends pointed toward the binding sites where the chloride ions are held extensively by the backbone amide nitrogen atoms from the helices. To understand the effectiveness of such binding structures, we carried out natural bond orbital analysis and energy decomposition analysis employing truncated active-site model systems for the bound chloride ions along the translocation pore of the EcClC proteins. Our results indicated that the chloride ions are stabilized in such a binding environment by electrostatic, polarization, and charge-transfer interactions with the backbone and a few side chains. Up to ~25% of the formal charges of the chloride ions were found smeared out to the surroundings primarily via charge transfer from the chloride's lone pair n(Cl) orbitals to the protein's antibonding σ*(N-H) or σ*(O-H) orbitals; those σ* orbitals are localized at the polar N-H and O-H bonds in the chloride's first solvation shells formed by the backbone amide groups and the side chains of residues Ser107, Arg147, Glu148, and Tyr445. Polarizations by the chloride ions were dominated by the redistribution of charge densities among the π orbitals and lone pair orbitals of the protein atoms, in particular the atoms of the backbone peptide links and of the side chains of Arg147, Glu148, and Tyr445. The substantial amounts of electron density involved in charge transfer and in polarization were consistent with the large energetic contributions by the two processes revealed by the energy decomposition analysis. The significant polarization and charge-transfer effects may have impacts on the mechanisms and dynamics of the chloride transport by the ClC proteins.

  14. Transfer efficiency of angular momentum in sum-frequency generation and control of its spin and orbital parts by varying polarization and frequency of fundamental beams

    Science.gov (United States)

    Perezhogin, I. A.; Grigoriev, K. S.; Potravkin, N. N.; Cherepetskaya, E. B.; Makarov, V. A.

    2017-08-01

    Considering sum-frequency generation in an isotropic chiral nonlinear medium, we analyze the transfer of the spin angular momentum of fundamental elliptically polarized Gaussian light beams to the signal beam, which appears as the superposition of two Laguerre-Gaussian modes with both spin and orbital angular momentum. Only for the circular polarization of the fundamental radiation is its angular momentum fully transferred to the sum-frequency beam; otherwise, part of it can be transferred to the medium. Its value, as well as the ratio of spin and orbital contributions in the signal beam, depends on the fundamental frequency ratio and the polarization of the incident beams. Higher energy conversion efficiency in sum-frequency generation does not always correspond to higher angular momentum conversion efficiency.

  15. Definition, technology readiness, and development cost of the orbit transfer vehicle engine integrated control and health monitoring system elements

    Science.gov (United States)

    Cannon, I.; Balcer, S.; Cochran, M.; Klop, J.; Peterson, S.

    1991-01-01

    An Integrated Control and Health Monitoring (ICHM) system was conceived for use on a 20 Klb thrust baseline Orbit Transfer Vehicle (OTV) engine. Considered for space used, the ICHM was defined for reusability requirements for an OTV engine service free life of 20 missions, with 100 starts and a total engine operational time of 4 hours. Functions were derived by flowing down requirements from NASA guidelines, previous OTV engine or ICHM documents, and related contracts. The elements of an ICHM were identified and listed, and these elements were described in sufficient detail to allow estimation of their technology readiness levels. These elements were assessed in terms of technology readiness level, and supporting rationale for these assessments presented. The remaining cost for development of a minimal ICHM system to technology readiness level 6 was estimated. The estimates are within an accuracy range of minus/plus 20 percent. The cost estimates cover what is needed to prepare an ICHM system for use on a focussed testbed for an expander cycle engine, excluding support to the actual test firings.

  16. Orbital transfer vehicle concept definition and system analysis study, 1985. Volume 5: Work breakdown structure and dictionary

    Science.gov (United States)

    Nelson, James H.; Callan, Daniel R.

    1985-01-01

    To establish consistency and visibility within the Orbital Transfer Vehicle (OTV) program, a preliminary work breakdown structure (WBS) and dictionary were developed. The dictionary contains definitions of terms to be used in conjunction with the WBS so that a clear understanding of the content of the hardware, function, and cost elements may be established. The OTV WBS matrix is a two-dimensional structure which shows the interrelationship of these dimensions: the hardware elements dimension and the phase and function dimension. The dimension of time cannot be shown graphically, but must be considered. Each cost entry varies with time so that it is necessary to know these cost values by year for budget planning and approval as well as for establishing cost streams for discounting purposes in the economic analysis. While a multiple dimensional approach may at first appear complex, it actually provides benefits which outweigh any concern. This structural interrelationship provides the capability to view and analyze the OTV costs from a number of different financial and management aspects. Cost may be summed by hardware groupings, phases, or functions. The WBS may be used in a number of dimensional or single listing format applications.

  17. TARGET/CRYOCHIL - THERMODYNAMIC ANALYSIS AND SUBSCALE MODELING OF SPACE-BASED ORBIT TRANSFER VEHICLE CRYOGENIC PROPELLANT RESUPPLY

    Science.gov (United States)

    Defelice, D. M.

    1994-01-01

    The resupply of the cryogenic propellants is an enabling technology for space-based transfer vehicles. As part of NASA Lewis's ongoing efforts in micro-gravity fluid management, thermodynamic analysis and subscale modeling techniques have been developed to support an on-orbit test bed for cryogenic fluid management technologies. These efforts have been incorporated into two FORTRAN programs, TARGET and CRYOCHIL. The TARGET code is used to determine the maximum temperature at which the filling of a given tank can be initiated and subsequently filled to a specified pressure and fill level without venting. The main process is the transfer of the energy stored in the thermal mass of the tank walls into the inflowing liquid. This process is modeled by examining the end state of the no-vent fill process. This state is assumed to be at thermal equilibrium between the tank and the fluid which is well mixed and saturated at the tank pressure. No specific assumptions are made as to the processes or the intermediate thermodynamic states during the filling. It is only assumed that the maximum tank pressure occurs at the final state. This assumption implies that, during the initial phases of the filling, the injected liquid must pass through the bulk vapor in such a way that it absorbs a sufficient amount of its superheat so that moderate tank pressures can be maintained. It is believed that this is an achievable design goal for liquid injection systems. TARGET can be run with any fluid for which the user has a properties data base. Currently it will only run for hydrogen, oxygen, and nitrogen since pressure-enthalpy data sets have been included for these fluids only. CRYOCHIL's primary function is to predict the optimum liquid charge to be injected for each of a series of charge-hold-vent chilldown cycles. This information can then be used with specified mass flow rates and valve response times to control a liquid injection system for tank chilldown operations. This will

  18. Effect of element size on the solution accuracies of finite-element heat transfer and thermal stress analyses of space shuttle orbiter

    Science.gov (United States)

    Ko, William L.; Olona, Timothy

    1987-01-01

    The effect of element size on the solution accuracies of finite-element heat transfer and thermal stress analyses of space shuttle orbiter was investigated. Several structural performance and resizing (SPAR) thermal models and NASA structural analysis (NASTRAN) structural models were set up for the orbiter wing midspan bay 3. The thermal model was found to be the one that determines the limit of finite-element fineness because of the limitation of computational core space required for the radiation view factor calculations. The thermal stresses were found to be extremely sensitive to a slight variation of structural temperature distributions. The minimum degree of element fineness required for the thermal model to yield reasonably accurate solutions was established. The radiation view factor computation time was found to be insignificant compared with the total computer time required for the SPAR transient heat transfer analysis.

  19. On-board orbit determination for low thrust LEO-MEO transfer by Consider Kalman Filtering and multi-constellation GNSS

    Science.gov (United States)

    Menzione, Francesco; Renga, Alfredo; Grassi, Michele

    2017-09-01

    In the framework of the novel navigation scenario offered by the next generation satellite low thrust autonomous LEO-to-MEO orbit transfer, this study proposes and tests a GNSS based navigation system aimed at providing on-board precise and robust orbit determination strategy to override rising criticalities. The analysis introduces the challenging design issues to simultaneously deal with the variable orbit regime, the electric thrust control and the high orbit GNSS visibility conditions. The Consider Kalman Filtering approach is here proposed as the filtering scheme to process the GNSS raw data provided by a multi-antenna/multi-constellation receiver in presence of uncertain parameters affecting measurements, actuation and spacecraft physical properties. Filter robustness and achievable navigation accuracy are verified using a high fidelity simulation of the low-thrust rising scenario and performance are compared with the one of a standard Extended Kalman Filtering approach to highlight the advantages of the proposed solution. Performance assessment of the developed navigation solution is accomplished for different transfer phases.

  20. Time-transfer experiments between satellite laser ranging ground stations via one-way laser ranging to the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Mao, D.; Sun, X.; Skillman, D. R.; Mcgarry, J.; Hoffman, E.; Neumann, G. A.; Torrence, M. H.; Smith, D. E.; Zuber, M. T.

    2014-12-01

    Satellite laser ranging (SLR) has long been used to measure the distance from a ground station to an Earth-orbiting satellite in order to determine the spacecraft position in orbit, and to conduct other geodetic measurements such as plate motions. This technique can also be used to transfer time between the station and satellite, and between remote SLR sites, as recently demonstrated by the Time Transfer by Laser Link (T2L2) project by the Centre National d'Etudes Spatiaes (CNES) and Observatorire de la Cote d'Azur (OCA) as well as the Laser Time Transfer (LTT) project by the Shanghai Astronomical Observatory, where two-way and one-way measurements were obtained at the same time. Here we report a new technique to transfer time between distant SLR stations via simultaneous one-way laser ranging (LR) to the Lunar Reconnaissance Orbiter (LRO) spacecraft at lunar distance. The major objectives are to establish accurate ground station times and to improve LRO orbit determination via these measurements. The results of these simultaneous LR measurements are used to compare the SLR station times or transfer time from one to the other using times-of-flight estimated from conventional radio frequency tracking of LRO. The accuracy of the time transfer depends only on the difference of the times-of-flight from each ground station to the spacecraft, and is expected to be at sub-nano second level. The technique has been validated by both a ground-based experiment and an experiment that utilized LRO. Here we present the results to show that sub-nanosecond precision and accuracy are achievable. Both experiments were carried out between the primary LRO-LR station, The Next Generation Satellite Laser Ranging (NGSLR) station, and its nearby station, Mobile Laser System (MOBLAS-7), both at Greenbelt, Maryland. The laser transmit time from both stations were recorded by the same event timer referenced to a Hydrogen maser. The results have been compared to data from a common All

  1. Shuttle and Transfer Orbit Thermal Analysis and Testing of the Chandra X-Ray Observatory Charge-Couple Device Imaging Spectrometer Radiator Shades

    Science.gov (United States)

    Sharp, John R.

    1999-01-01

    Thermal analyses of the Shuttle and Transfer Orbit of the Advanced X-Ray Astrophysics Facility Charge-Coupled Device (CCD) Imaging Spectrometer (ACIS), one of two science instruments on the Chandra X-Ray Observatory, revealed a low-earth orbit (LEO) overheating problem on the goldized Kapton faces of two radiator shades. The shades were coated with the goldized Kapton to provide a low hemispherical emittance to minimize direct and backloaded heating from the sun and the observatory and high specularity to optimize the coupling to space on two passive radiators which cool the focal plane to -120 C +/- 1 C during on-orbit operations. Since the observatory has a highly elliptical final orbit of 10,000 kilometers by 140,000 kilometers and the ACIS radiators and shades are oriented anti-sun, the high solar absorptance to emittance ratio of the goldized Kapton was not an issue. However, during Shuttle bay-to-earth operations, the short duration solar heating occurring near the eclipse entry and exit resulted in shade temperatures in excess of the cure temperature of the adhesive used to bond the goldized Kapton and honeycomb face-sheets. The detailed thermal analysis demonstrating the LEO overheating as well as the redesign options and thermal testing of a redesigned development unit shade are presented.

  2. Alternative Transfers to the NEOs 99942 Apophis, 1994 WR12, and 2007 UW1 via Derived Trajectories from Periodic Orbits of Family G

    Directory of Open Access Journals (Sweden)

    C. F. de Melo

    2009-01-01

    Full Text Available Swing-by techniques are extensively used in interplanetary missions to minimize fuel consumption and to raise payloads of spacecrafts. The effectiveness of this type of maneuver has been proven since the beginning of space exploration. According to this premise, we have explored the existence of a natural and direct link between low Earth orbits and the lunar sphere of influence to get low-energy transfer trajectories to the Near Earth Objects (NEOs 99942 Apophis, 1994 WR12, and 2007 UW1 through swing-bys with the Moon. The existence of this link is related to a family of retrograde periodic orbits around the Lagrangian equilibrium point L1 predicted for the circular, planar, restricted three-body Earth-Moon-particle problem. The trajectories in this link are sensitive to small disturbances. This enables them to be conveniently diverted reducing so the cost of the swing-by maneuver. These maneuvers allow a gain in energy sufficient for the trajectories to escape from the Earth-Moon system and to stabilize in heliocentric orbits between the Earth and Venus or Earth and Mars. Therefore, the trajectories have sufficient reach to intercept the NEOs' orbits.

  3. Orbit Control Scheme of Automated Transfer Vehicle%自动转移飞行器的轨控总体方案

    Institute of Scientific and Technical Information of China (English)

    靳永强; 毕雨雯

    2011-01-01

    The orbit control scheme and technology of the automated transfer vehicle (ATV) of ESA were discussed in this paper. The flying scheme, the configuration of the sensor system and actuators, and the different orbit control strategies during the phasing, homing, approaching and final approaching were analyzed.%介绍了欧空局的自动转移飞行器(ATV)的轨道控制方案和技术。给出了ATV的飞行方案、测量敏感器和执行机构的配置,以及在空间站调相段、寻的段、接近段和最终逼近段的轨控策略。

  4. Charge-transfer mechanism for electrophilic aromatic nitration and nitrosation via the convergence of (ab initio) molecular-orbital and Marcus-Hush theories with experiments.

    Science.gov (United States)

    Gwaltney, Steven R; Rosokha, Sergiy V; Head-Gordon, Martin; Kochi, Jay K

    2003-03-19

    The highly disparate rates of aromatic nitrosation and nitration, despite the very similar (electrophilic) properties of the active species: NO(+) and NO(2)(+) in Chart 1, are quantitatively reconciled. First, the thorough mappings of the potential-energy surfaces by high level (ab initio) molecular-orbital methodologies involving extensive coupled-cluster CCSD(T)/6-31G optimizations establish the intervention of two reactive intermediates in nitration (Figure 8) but only one in nitrosation (Figure 7). Second, the same distinctive topologies involving double and single potential-energy minima (Figures 6 and 5) also emerge from the semiquantitative application of the Marcus-Hush theory to the transient spectral data. Such a striking convergence from quite different theoretical approaches indicates that the molecular-orbital and Marcus-Hush (potential-energy) surfaces are conceptually interchangeable. In the resultant charge-transfer mechanism, the bimolecular interactions of arene donors with both NO(+) and NO(2)(+) spontaneously lead (barrierless) to pi-complexes in which electron transfer is concurrent with complexation. Such a pi-complex in nitration is rapidly converted to the sigma-complex, whereas this Wheland adduct in nitrosation merely represents a high energy (transition-state) structure. Marcus-Hush analysis thus demonstrates how the strongly differentiated (arene) reactivities toward NO(+) and NO(2)(+) can actually be exploited in the quantitative development of a single coherent (electron-transfer) mechanism for both aromatic nitrosation and nitration.

  5. Cryogenic on-orbit liquid depot storage acquisition and transfer (COLD-SAT) experiment subsystem instrumentation and wire harness design report

    Science.gov (United States)

    Edwards, Lawrence G.

    1994-01-01

    Subcritical cryogens such as liquid hydrogen (LH2) and liquid oxygen (LO2) are required for space based transportation propellant, reactant, and life support systems. Future long-duration space missions will require on-orbit systems capable of long-term cryogen storage and efficient fluid transfer capabilities. COLD-SAT, which stands for cryogenic orbiting liquid depot-storage acquisition and transfer, is a free-flying liquid hydrogen management flight experiment. Experiments to determine optimum methods of fluid storage and transfer will be performed on the COLD-SAT mission. The success of the mission is directly related to the type and accuracy of measurements made. The instrumentation and measurement techniques used are therefore critical to the success of the mission. This paper presents the results of the COLD-SAT experiment subsystem instrumentation and wire harness design effort. Candidate transducers capable of fulfilling the COLD-SAT experiment measurement requirements are identified. Signal conditioning techniques, data acquisition requirements, and measurement uncertainty analysis are presented. Electrical harnessing materials and wiring techniques for the instrumentation designed to minimize heat conduction to the cryogenic tanks and provide optimum measurement accuracy are listed.

  6. Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

    Science.gov (United States)

    Zhao, Wei-Ning; Fang, Wei; Sun, Li-Wei; Cui, Li-Hong; Wang, Yu-Peng

    2016-09-01

    In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors, a transfer chain consisting of a fiber coupling monochromator (FBM) and an integrating sphere transfer radiometer (ISTR) was designed in this paper. Depending on the Sun, this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band (RSB) covering 300-2500 nm with a spectral bandwidth of 0.5-6 nm. It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard. This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor, including the weak spectral signal measurement with uncertainty of 0.28%. According to the peculiar design and comprehensive uncertainty analysis, it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%. The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality. Project supported by the National Natural Science Foundation of China (Grant No. 41474161) and the National High-Technology Program of China (Grant No. 2015AA123703).

  7. Receding Horizon Control of the Spacecraft for Transferring between Halo Orbits%航天器Halo轨道间转移的滚动时域控制

    Institute of Scientific and Technical Information of China (English)

    彭海军; 谭述君; 吴志刚

    2012-01-01

    针对航天器在日/地系统共线平动点附近Halo轨道族之间的轨道转移问题,提出了一种在线实时求解滚动时域控制的新方法.首先采用高效的辛自适应非线性最优控制数值算法,离线规划出航天器在不同Halo轨道之间转移的最优轨迹和最优控制输入.然后提出一种在线实时求解滚动时域控制的新方法,基于已规划好的最优转移轨迹,应用滚动时域控制方法完成航天器在初始入轨偏差下的在线实时制导控制任务.最后的非线性动力学系统数值仿真结果表明:所提出的求解滚动时域控制的方法具有高效率特点,能够在线实时求解航天器在Halo轨道之间转移的制导控制问题,并很快消除初始入轨误差的影响.%A new method is presented for solving the on-line receding horizon control problem in real time, and it has been successfully applied into the transfer mission between the Halo orbits near collinear Libration points in the Sun-Earth system. First, by employing the efficient symplectic adaptive algorithm for nonlinear optimal control, the optimal transfer trajectory and control input are programmed off-line. Then, a new on-line real time numerical algorithm is proposed for solving the receding horizon control. Based on the optimal transfer trajectory and control, the transfer mission of the spacecraft with initial injection error is accomplished by using the receding horizon control method. Finally, the receding horizon controller is implemented for the transfer mission between Halo orbits. Finally numerical simulation results for nonlinear dynamics system show that the numerical method proposed for receding horizon control is effective, and it can solve the transfer mission between Halo orbits in real time. Beside, the initial injection error can be removed quickly.

  8. SeaWiFS Postlaunch Technical Report Series. Volume 5; The SeaWiFS Solar Radiation-Based Calibration and the Transfer-to-Orbit Experiment

    Science.gov (United States)

    Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Barnes, Robert A.; Eplee, Robert E., Jr.; Biggar, Stuart F.; Thome, Kurtis J.; Zalewski, Edward F.; Slater, Philip N.; Holmes, Alan W.

    1999-01-01

    The solar radiation-based calibration (SRBC) of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) was performed on 1 November 1993. Measurements were made outdoors in the courtyard of the instrument manufacturer. SeaWiFS viewed the solar irradiance reflected from the sensor's diffuser in the same manner as viewed on orbit. The calibration included measurements using a solar radiometer designed to determine the transmittances of principal atmospheric constituents. The primary uncertainties in the outdoor measurements are the transmission of the atmosphere and the reflectance of the diffuser. Their combined uncertainty is about 5 or 6%. The SRBC also requires knowledge of the extraterrestrial solar spectrum. Four solar models are used. When averaged over the responses of the SeaWiFS bands, the irradiance models agree at the 3.6% level, with the greatest difference for SeaWiFS band 8. The calibration coefficients from the SRBC are lower than those from the laboratory calibration of the instrument in 1997. For a representative solar model, the ratios of the SRBC coefficients to laboratory values average 0.962 with a standard deviation of 0.012. The greatest relative difference is 0.946 for band 8. These values are within the estimated uncertainties of the calibration measurements. For the transfer-to-orbit experiment, the measurements in the manufacturer's courtyard are used to predict the digital counts from the instrument on its first day on orbit (August 1, 1997). This experiment requires an estimate of the relative change in the diffuser response for the period between the launch of the instrument and its first solar measurements on orbit (September 9, 1997). In relative terms, the counts from the instrument on its first day on orbit averaged 1.3% higher than predicted, with a standard deviation of 1.2% and a greatest difference of 2.4% or band 7. The estimated uncertainty for the transfer-to-orbit experiment is about 3 or 4%.

  9. Electron density characteristics and charge transfer effect of hydrogen bond O-H···Pt(II): atoms in molecules study and natural bond orbital analysis

    Science.gov (United States)

    Zhang, Guiqiu; Li, Xiwen; Li, Yan; Chen, Dezhan

    2013-11-01

    In this report, we extended the works of Rizzato et al. [Angew. Chem. Int. Ed. 49, 7440 (2010)] on the nature of O-H...Pt hydrogen bond in trans-[PtCl2(NH3)(N-glycine)].H2O(1.H2O) complex, by computational study of O-H...Pt interaction in [NBu4][Pt(C6F5)3(8-hydroxyquinaldine)], with emphasis on charge transfer effect in this interaction of platinum(II) and hydrogen atom. According to the crystallographic geometry reported by José María Casas et al., [NBu4][Pt(C6F5)3(8-hydroxyquinaldine)] possesses one O-H...Pt hydrogen bridging interaction, similar to the case in trans-[PtCl2(NH3)(N-glycine)].H2O(1.H2O) complex. On the basis of topological criteria of electron density, we characterised this O-H...Pt interaction. Charge transferred between platinum(II) and σ*O-H orbital in this complex was calculated by using NBO method. The stabilised energy associated to charge transfer was estimated using a direct proportionality, that is 2-3 eV per electron transferred. Charge transfer effects in O-H...Pt hydrogen bonds were studied for these two complexes. Our results indicate that the interaction of O-H...Pt is closed-shell in nature with significant charge transfer, and that charge transfer effect is not negligible in the interaction of O-H...Pt. The second conclusion is different from the result of Rizzato et al.

  10. Orbital alignment dependence of electron transfer cross sections. I : H+-Na(3p) near the matching velocity

    NARCIS (Netherlands)

    Müller, U.; Meijer, H.A.J.; Holme, N.C.R.; Kmit, M.; Lauritsen, J.H.V.; Pedersen, J.O.P.; Richter, C.; Thomsen, J.W.; Andersen, N.; Nielsen, S.E.

    1995-01-01

    This paper reports experimental and theoretical results for the influence of target excitation and orbital alignment on the charge exchange process for the system H+-Na(3s,3p). The experimental velocity range covers for the first time the region around and beyond the "matching velocity" of 0.47 a.u.

  11. CNDO/SCF molecular orbital structural studies and charge transfer complex formation between 4,4’-dimethoxydiquinone and uracil

    Directory of Open Access Journals (Sweden)

    Anwar S. El-Shahawy

    2004-12-01

    Full Text Available Through CNDO/SCF molecular orbital calculations, the structure of 4,4’-dimethoxy- diquinone (DQ has been discussed and compared with some related compounds. The electron transfer between DQ and uracil was studied in ethanol as an interaction medium. The ionization potentials and the electron affinities of the studied molecules have been calculated in addition to their charge densities giving the columbic potential energy of the donor and acceptor. The experimental charge transfer band lies at 500 nm. The electronic transitions have been calculated for the singlet and triplet transitions in uracil and DQ molecules using the SCF eigenvectors of the two HOMO’s, ψn-1 and ψ n, and the two LUMO’s, ψ n+1 and ψ n+2, using CI theory. The calculated electronic transitions are compared with those of the experimental data to verify the non-planar structure of the DQ molecule.

  12. Single-event and total-dose effects in geo-stationary transfer orbit during solar-activity maximum period measured by the Tsubasa satellite

    Science.gov (United States)

    Koshiishi, H.; Kimoto, Y.; Matsumoto, H.; Goka, T.

    The Tsubasa satellite developed by the Japan Aerospace Exploration Agency was launched in Feb 2002 into Geo-stationary Transfer Orbit GTO Perigee 500km Apogee 36000km and had been operated well until Sep 2003 The objective of this satellite was to verify the function of commercial parts and new technologies of bus-system components in space Thus the on-board experiments were conducted in the more severe radiation environment of GTO rather than in Geo-stationary Earth Orbit GEO or Low Earth Orbit LEO The Space Environment Data Acquisition equipment SEDA on board the Tsubasa satellite had the Single-event Upset Monitor SUM and the DOSimeter DOS to evaluate influences on electronic devices caused by radiation environment that was also measured by the particle detectors of the SEDA the Standard DOse Monitor SDOM for measurements of light particles and the Heavy Ion Telescope HIT for measurements of heavy ions The SUM monitored single-event upsets and single-event latch-ups occurred in the test sample of two 64-Mbit DRAMs The DOS measured accumulated radiation dose at fifty-six locations in the body of the Tsubasa satellite Using the data obtained by these instruments single-event and total-dose effects in GTO during solar-activity maximum period especially their rapid changes due to solar flares and CMEs in the region from L 1 1 through L 11 is discussed in this paper

  13. Suppression of angular momentum transfer in cold collisions of transition metal atoms in ground States with nonzero orbital angular momentum.

    Science.gov (United States)

    Hancox, Cindy I; Doret, S Charles; Hummon, Matthew T; Krems, Roman V; Doyle, John M

    2005-01-14

    The Zeeman relaxation rate in cold collisions of Ti(3d(2)4s(2) 3F2) with He is measured. We find that collisional transfer of angular momentum is dramatically suppressed due to the presence of the filled 4s(2) shell. The degree of electronic interaction anisotropy, which is responsible for Zeeman relaxation, is estimated to be about 200 times smaller in the Ti-He complex than in He complexes with typical non-S-state atoms.

  14. Boundary problem solution of an optimal control transfer between circular orbits for an electric propulsion spacecraft in an irregular gravitational field of an asteroid

    Science.gov (United States)

    Shornikov, Andrey; Starinova, Olga

    2017-01-01

    There is a problem to control spacecraft's motion near objects with irregular gravitational fields as asteroids. In this paper we present a mathematical model of spacecraft motion with an electric propulsion engine in an irregular non-spherical gravitational field of the asteroid Eros 433. We propose to use the model of single gravity points for simulation of the motion of a spacecraft in the irregular gravitational field. The equations of spacecraft motion are corresponding equations of the n-body problem. A boundary task of the control spacecraft's transfer between circular orbits from 200 km to 100 km is considered. Authors propose a combination of the Pontryagin's maximum principle and the Newton's step by step approximation as solutions methods for the boundary problem.

  15. TRANSFER

    African Journals Online (AJOL)

    “Chemistry Department, Kenyatta University, P. 0. Box 43844 ... harvester (X) [L 2] in a manner consistent with the following Forster equation for long range energy transfer [3-7]. .... sensitive foods, chemical reactors and essences. Recently we ...

  16. Spin-orbit alignment for KELT-7b and HAT-P-56b via Doppler tomography with TRES

    Science.gov (United States)

    Zhou, George; Latham, David W.; Bieryla, Allyson; Beatty, Thomas G.; Buchhave, Lars A.; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.

    2016-08-01

    We present Doppler tomographic analyses for the spectroscopic transits of KELT-7b and HAT-P-56b, two hot-Jupiters orbiting rapidly rotating F-dwarf host stars. These include analyses of archival Tillinghast Reflector Echelle Spectrograph (TRES) observations for KELT-7b, and a new TRES transit observation of HAT-P-56b. We report spin-orbit aligned geometries for KELT-7b (2.7° ± 0.6°) and HAT-P-56b (8° ± 2°). The host stars KELT-7 and HAT-P-56 are among some of the most rapidly rotating planet-hosting stars known. We examine the tidal re-alignment model for the evolution of the spin-orbit angle in the context of the spin rates of these stars. We find no evidence that the rotation rates of KELT-7 and HAT-P-56 have been modified by star-planet tidal interactions, suggesting that the spin-orbit angle of systems around these hot stars may represent their primordial configuration. In fact, KELT-7 and HAT-P-56 are two of three systems in supersynchronous, spin-orbit aligned states, where the rotation periods of the host stars are faster than the orbital periods of the planets.

  17. Orbital-optimized coupled-electron pair theory and its analytic gradients: accurate equilibrium geometries, harmonic vibrational frequencies, and hydrogen transfer reactions.

    Science.gov (United States)

    Bozkaya, Uğur; Sherrill, C David

    2013-08-07

    Orbital-optimized coupled-electron pair theory [or simply "optimized CEPA(0)," OCEPA(0), for short] and its analytic energy gradients are presented. For variational optimization of the molecular orbitals for the OCEPA(0) method, a Lagrangian-based approach is used along with an orbital direct inversion of the iterative subspace algorithm. The cost of the method is comparable to that of CCSD [O(N(6)) scaling] for energy computations. However, for analytic gradient computations the OCEPA(0) method is only half as expensive as CCSD since there is no need to solve the λ2-amplitude equation for OCEPA(0). The performance of the OCEPA(0) method is compared with that of the canonical MP2, CEPA(0), CCSD, and CCSD(T) methods, for equilibrium geometries, harmonic vibrational frequencies, and hydrogen transfer reactions between radicals. For bond lengths of both closed and open-shell molecules, the OCEPA(0) method improves upon CEPA(0) and CCSD by 25%-43% and 38%-53%, respectively, with Dunning's cc-pCVQZ basis set. Especially for the open-shell test set, the performance of OCEPA(0) is comparable with that of CCSD(T) (ΔR is 0.0003 Å on average). For harmonic vibrational frequencies of closed-shell molecules, the OCEPA(0) method again outperforms CEPA(0) and CCSD by 33%-79% and 53%-79%, respectively. For harmonic vibrational frequencies of open-shell molecules, the mean absolute error (MAE) of the OCEPA(0) method (39 cm(-1)) is fortuitously even better than that of CCSD(T) (50 cm(-1)), while the MAEs of CEPA(0) (184 cm(-1)) and CCSD (84 cm(-1)) are considerably higher. For complete basis set estimates of hydrogen transfer reaction energies, the OCEPA(0) method again exhibits a substantially better performance than CEPA(0), providing a mean absolute error of 0.7 kcal mol(-1), which is more than 6 times lower than that of CEPA(0) (4.6 kcal mol(-1)), and comparing to MP2 (7.7 kcal mol(-1)) there is a more than 10-fold reduction in errors. Whereas the MAE for the CCSD method is

  18. Orbital transfer vehicle concept definition and system analysis study, 1985. Volume 2: OTV concept definition and evaluation. Book 4: Operations

    Science.gov (United States)

    Mitchell, Jack C.; Keeley, J. T.

    1985-01-01

    The benefits of the reusable Space Shuttle and the advent of the new Space Station hold promise for increasingly effective utilization of space by the scientific and commercial as well as military communities. A high energy reusable oribital transfer vehicle (OTV) represents an additional capability which also exhibits potential for enhancing space access by allowing more ambitious missions and at the same time reducing launch costs when compared to existing upper stages. This section, Vol. 2: Book 4, covers launch operations and flight operations. The launch operations section covers analyses of ground based and space based vehicles, launch site facilities, logistics requirements, propellant loading, space based maintenance and aft cargo carrier access options. The flight operations sections contain summary descriptions of ground based and space based OTV missions, operations and support requirements, and a discussion of fleet implications.

  19. Spin orbit alignment for KELT-7b and HAT-P-56b via Doppler tomography with TRES

    CERN Document Server

    Zhou, George; Bieryla, Allyson; Beatty, Thomas G; Buchhave, Lars A; Esquerdo, Gilbert A; Berlind, Perry; Calkins, Michael L

    2016-01-01

    We present Doppler tomographic analyses for the spectroscopic transits of KELT-7b and HAT-P-56b, two hot-Jupiters orbiting rapidly rotating F-dwarf host stars. These include analyses of archival TRES observations for KELT-7b, and a new TRES transit observation of HAT-P-56b. We report spin-orbit aligned geometries for KELT-7b (2.7 +/- 0.6 deg) and HAT-P-56b (8 +/- 2 deg). The host stars KELT-7 and HAT-P-56 are among some of the most rapidly rotating planet-hosting stars known. We examine the tidal re-alignment model for the evolution of the spin-orbit angle in the context of the spin rates of these stars. We find no evidence that the rotation rates of KELT-7 and HAT-P-56 have been modified by star-planet tidal interactions, suggesting that the spin-orbit angle of systems around these hot stars may represent their primordial configuration. In fact, KELT-7 and HAT-P-56 are two of three systems in super-synchronous, spin-orbit aligned states, where the rotation periods of the host stars are faster than the orbita...

  20. 载人登月转移轨道偏差传播机理分析与稳健性设计%Analysis of transfer orbit deviation propagation mechanism and robust design for manned lunar landing

    Institute of Scientific and Technical Information of China (English)

    贺波勇; 李海阳; 张波

    2013-01-01

    载人登月转移轨道具有飞行时间长,动力学模型复杂,非线性强且变系数的特点,而载人登月工程对转移轨道可靠性要求极高,研究地月转移轨道偏差传播机理和轨道稳健性设计不仅具有工程意义,更具有探索地月空间复杂引力场对轨道偏差作用的科学意义。本文首先分析了日地月中心引力和地球J2项摄动等主要作用力对转移轨道偏差的作用范围与影响大小,其次提出了一种基于标称轨道数据的变系数非线性动力学系统偏差传播机理解析分析方法,最后构建了基于偏差传播矩阵的转移轨道稳健性评价指标,并基于NSGA-II (Nondominated Sorting Genetic Algorithms)算法求解了载人登月转移轨道稳健性优化设计问题。仿真结果表明,本文提出的偏差传播机理分析方法能快速准确地求解出载人登月转移轨道偏差传播矩阵,利用偏差传播矩阵进行协方差分析和中途修正脉冲计算是简单准确的,考虑稳健性的转移轨道优化设计可以提高标称轨道品质。%Earth-moon transfer orbit for manned lunar landing needs a long flight time, complex, nonlinear and variable coefficient dynamics model, and asks for a high reliability. Analysis of deviation propagation mechanism and robust design of transfer orbit are investigated in this paper. It is not only practical for projecting, but also significant for exploring the role of earth-moon space gravitational field upon transfer orbit deviation. This paper analyses firstly the boundary and the amplitude of the sun, earth, and moon central gravitation, the earth J2 perturbation that affect the transfer orbit deviation transmission. And then a method to analyse the deviation propagation mechanism based on nominal orbital data is obtained analytically. A robust indicator of transfer orbit based on deviation transition matrix is proposed,and a robust optimization design method that employs NSGA

  1. Orbiter OMS and RCS technology

    Science.gov (United States)

    Boudreaux, R. A.

    1982-01-01

    Orbiter Orbital Maneuver Subsystem (OMS) and Reaction Control Subsystem (RCS) tankage has proved to be highly successful in shuttle flights on-orbit propellant transfer tests were done. Tank qualification tests along with flight demonstrations were carried out future uses of storable propellants are cited.

  2. 利用能量分析方法研究太阳帆的轨道转移%The orbit transfer design of solar sail based on energy analysis

    Institute of Scientific and Technical Information of China (English)

    张轲; 周凤歧; 祝开建; 熊菁

    2011-01-01

    Aim To study the orbit transfer problem of solar sails from a circular orbit around the Earth to the artificial Lagrange points under the conditions of Hill's restricted three-body problem. Methods Energy analysis method is used. In the parking orbit around the Earth, solar sail is expanded and the impulse is applied simultaneously. Then solar sail flies into the transfer orbit of artificial Lagrange point. Without active control, under certain attitude angle, solar sail moves into artificial Lagrange point stably. Results The analytical method is used to analyze the theoretical optimum of the orbital transfer, the result is close to the value of numerical result. Conclusion When the solar sail's attitude angle remains unchanged, it determines the constant of generalized energy. If attitude angle stays in several areas, an optimal transfer orbit exists. In these areas, the right attitude angle can be chosen to minimize the transfer energy from a certain orbit height to artificial Lagrange point. Meanwhile the transfer time is also shorter.%目的 考虑在Hill限制性三体问题的条件下,研究太阳帆从地球附近的圆轨道到人工拉格朗日点的轨道转移问题.方法 利用能量分析的方法,在地球附近的停泊轨道施加脉冲同时展开太阳帆,让太阳帆进入人工拉格朗日点的转移轨道,在无主动控制的情况下,太阳帆以某一姿态角沿转移轨道被动稳定地飞行到人工拉格朗日点.结果 利用解析方法分析了轨道转移的理论最优值,并与数值结果进行比较发现两者非常接近.结论 当太阳帆的姿态角保持不变的情况下,太阳帆的姿态角决定了太阳帆的广义能量常数.姿态角在几个区域内时,存在着最优转移轨道.在这些区域内,可以选择合适的姿态角使得从某一个轨道高度到人工拉格朗日点的转移能量最小,同时转移时间也较小.

  3. Orbital-selective charge transfer at oxygen-deficient LaAlO3/SrTiO3(001) interfaces

    Science.gov (United States)

    Ong, P. V.; Lee, Jaichan

    2013-05-01

    Density-functional theory within the local density approximation + Hubbard U approach was used to study interface electronic structures in stoichiometric and oxygen-deficient LaAlO3/SrTiO3 (LAO/STO) superlattices with regularly spaced n-type and p-type interfaces. Asymmetric behaviors between complementary n-type and p-type interfaces were revealed in terms of orbital-selective charge transfer. Extra electrons induced by oxygen vacancies at the p-type interface easily spread to the n-type interface and occupy the Ti 3dxyorbitals, while those induced by the vacancies at the n-type interface are strictly confined and reside in Ti 3dx2-y2 and/or 3d3z2-r2 orbtials. The electronic behavior of oxygen vacancies at the LAO/STO interfaces and the possibility of distinguishing between intrinsic electronic states, which are induced by the polar catastrophe, and extrinsic states due to oxygen vacancies are discussed in detail.

  4. Orbital cellulitis

    Science.gov (United States)

    ... hemolytic streptococci may also cause orbital cellulitis. Orbital cellulitis infections in children may get worse very quickly and ... in the space around the eye. An orbital cellulitis infection can get worse very quickly. A person with ...

  5. Solar sail heliocentric transfer orbit control based on analytical control laws%基于解析控制律的太阳帆星际转移轨道控制

    Institute of Scientific and Technical Information of China (English)

    史晓宁; 郭继峰; 荣思远; 崔乃刚

    2013-01-01

    Solar sail spacecrafts can provide motivation rely on reflecting the sun photons, so that it is suitable for long distance interstellar transfer task. Aiming at the problem of solar sail interstellar transfer orbit control, a new analytical control law is presented. This control law can realize the combination control of each orbit elements by setting the blending weights. The modified equinoctial orbital elements are introduced to the optimal derivation of the analytical optimal control law, and numerical simulations for the method are performed based on mercury exploration mission. Simulation results show that, the proposed control law has higher computational speed and the capability of realizing the combination control of each orbit elements, thus the solar sail interstellar transfer orbit can be obtained, which can satisfy the requirements of the project.%太阳帆航天器可依靠反射太阳光子提供动力,因此较适用于远距离的星际转移任务.针对太阳帆航天器星际转移轨道控制问题,提出一种新的解析最优控制律,通过设定混合权重对各轨道根数进行联合控制.引入改进春分点轨道根数对解析控制律进行了优化推导,并以水星探测任务为背景进行了相应的仿真分析.仿真结果表明,该控制律计算速度较快,可对各个轨道根数进行联合控制,从而得到满足工程要求的太阳帆航天器星际转移轨道.

  6. Electronic Coupling Calculations for Bridge-Mediated Charge Transfer Using Constrained Density Functional Theory (CDFT) and Effective Hamiltonian Approaches at the Density Functional Theory (DFT) and Fragment-Orbital Density Functional Tight Binding (FODFTB) Level

    Energy Technology Data Exchange (ETDEWEB)

    Gillet, Natacha; Berstis, Laura; Wu, Xiaojing; Gajdos, Fruzsina; Heck, Alexander; de la Lande, Aurelien; Blumberger, Jochen; Elstner, Marcus

    2016-10-11

    In this article, four methods to calculate charge transfer integrals in the context of bridge-mediated electron transfer are tested. These methods are based on density functional theory (DFT). We consider two perturbative Green's function effective Hamiltonian methods (first, at the DFT level of theory, using localized molecular orbitals; second, applying a tight-binding DFT approach, using fragment orbitals) and two constrained DFT implementations with either plane-wave or local basis sets. To assess the performance of the methods for through-bond (TB)-dominated or through-space (TS)-dominated transfer, different sets of molecules are considered. For through-bond electron transfer (ET), several molecules that were originally synthesized by Paddon-Row and co-workers for the deduction of electronic coupling values from photoemission and electron transmission spectroscopies, are analyzed. The tested methodologies prove to be successful in reproducing experimental data, the exponential distance decay constant and the superbridge effects arising from interference among ET pathways. For through-space ET, dedicated p-stacked systems with heterocyclopentadiene molecules were created and analyzed on the basis of electronic coupling dependence on donor-acceptor distance, structure of the bridge, and ET barrier height. The inexpensive fragment-orbital density functional tight binding (FODFTB) method gives similar results to constrained density functional theory (CDFT) and both reproduce the expected exponential decay of the coupling with donor-acceptor distances and the number of bridging units. These four approaches appear to give reliable results for both TB and TS ET and present a good alternative to expensive ab initio methodologies for large systems involving long-range charge transfers.

  7. Electronic Coupling Calculations for Bridge-Mediated Charge Transfer Using Constrained Density Functional Theory (CDFT) and Effective Hamiltonian Approaches at the Density Functional Theory (DFT) and Fragment-Orbital Density Functional Tight Binding (FODFTB) Level.

    Science.gov (United States)

    Gillet, Natacha; Berstis, Laura; Wu, Xiaojing; Gajdos, Fruzsina; Heck, Alexander; de la Lande, Aurélien; Blumberger, Jochen; Elstner, Marcus

    2016-10-11

    In this article, four methods to calculate charge transfer integrals in the context of bridge-mediated electron transfer are tested. These methods are based on density functional theory (DFT). We consider two perturbative Green's function effective Hamiltonian methods (first, at the DFT level of theory, using localized molecular orbitals; second, applying a tight-binding DFT approach, using fragment orbitals) and two constrained DFT implementations with either plane-wave or local basis sets. To assess the performance of the methods for through-bond (TB)-dominated or through-space (TS)-dominated transfer, different sets of molecules are considered. For through-bond electron transfer (ET), several molecules that were originally synthesized by Paddon-Row and co-workers for the deduction of electronic coupling values from photoemission and electron transmission spectroscopies, are analyzed. The tested methodologies prove to be successful in reproducing experimental data, the exponential distance decay constant and the superbridge effects arising from interference among ET pathways. For through-space ET, dedicated π-stacked systems with heterocyclopentadiene molecules were created and analyzed on the basis of electronic coupling dependence on donor-acceptor distance, structure of the bridge, and ET barrier height. The inexpensive fragment-orbital density functional tight binding (FODFTB) method gives similar results to constrained density functional theory (CDFT) and both reproduce the expected exponential decay of the coupling with donor-acceptor distances and the number of bridging units. These four approaches appear to give reliable results for both TB and TS ET and present a good alternative to expensive ab initio methodologies for large systems involving long-range charge transfers.

  8. New model of angular momentum transfer from the rotating central body of a two-body system into the orbital motion of this system (with application to the earth-moon system)

    CERN Document Server

    Schmutzer, E

    2005-01-01

    In a previous paper we treated within the framework of our Projective Unified Field Theory (Schmutzer 2004, Schmutzer 2005a) the 2-body system (e.g. earth-moon system) with a rotating central body in a rather abstract manner. Here a concrete model of the transfer of angular momentum from the rotating central body to the orbital motion of the whole 2-body system is presented, where particularly the transfer is caused by the inhomogeneous gravitational force of the moon acting on the oceanic waters of the earth, being modeled by a spherical shell around the solid earth. The theory is numerically tested. Key words: transfer of angular momentum from earth to moon, action of the gravitational force of the moon on the waters of the earth.

  9. LLOFX earth orbit to lunar orbit delta V estimation program user and technical documentation

    Science.gov (United States)

    1988-01-01

    The LLOFX computer program calculates in-plane trajectories from an Earth-orbiting space station to Lunar orbit in such a way that the journey requires only two delta V burns (one to leave Earth circular orbit and one to circularize into Lunar orbit). The program requires the user to supply the Space Station altitude and Lunar orbit altitude (in km above the surface), and the desired time of flight for the transfer (in hours). It then determines and displays the trans-Lunar injection (TLI) delta V required to achieve the transfer, the Lunar orbit insertion (LOI) delta V required to circularize the orbit around the Moon, the actual time of flight, and whether the transfer orbit is elliptical or hyperbolic. Return information is also displayed. Finally, a plot of the transfer orbit is displayed.

  10. Congenital orbital teratoma

    Directory of Open Access Journals (Sweden)

    Shereen Aiyub

    2013-01-01

    Full Text Available 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 patient underwent a lid-sparing exenteration with frozen section control of the apical margin. A dermis fat graft from the groin was placed beneath the lid skin to provide volume. Histopathology revealed mature tissues from each of the three germ cell layers which confirmed the diagnosis of mature teratoma. We describe the successful use of demis fat graft in socket reconstruction following lid-sparing exenteration for congenital orbital teratoma.

  11. System technology analysis of aeroassisted orbital transfer vehicles: Moderate lift/drag (0.75-1.5). Volume 3: Cost estimates and work breakdown structure/dictionary, phase 1 and 2

    Science.gov (United States)

    1985-01-01

    Technology payoffs of representative ground based (Phase 1) and space based (Phase 2) mid lift/drag ratio aeroassisted orbit transfer vehicles (AOTV) were assessed and prioritized. A narrative summary of the cost estimates and work breakdown structure/dictionary for both study phases is presented. Costs were estimated using the Grumman Space Programs Algorithm for Cost Estimating (SPACE) computer program and results are given for four AOTV configurations. The work breakdown structure follows the standard of the joint government/industry Space Systems Cost Analysis Group (SSCAG). A table is provided which shows cost estimates for each work breakdown structure element.

  12. Application and analysis of formation satellites cluster orbit transfer based on genetic algorithm%遗传算法在编队卫星群轨道机动中的应用分析

    Institute of Scientific and Technical Information of China (English)

    李京生; 邓忠民

    2009-01-01

    Orbit transfer of formation satellites was a potential way for future spacecrafts. The Lambert maneuver problem of formation satellites with initial and target positions was studied. Relative motion model including central orbit elements and perturbation was set up using Gim-Alfriend matrix, and an impulse thrust control strategy for coordinated formation keeping on transfer orbit was designed. Genetic algorithm (GA) was applied to optimize the maneuver of formation satellites, with the goal to minimize the total fuel consumption, or weighted index which concerns the fuel consumption and time duration. Factors affecting fuel consumption were analyzed. Simulation results indicate that GA is available to solve the maneuver problem of formation satellites.%卫星群机动是航天器发展的一个方向.针对编队卫星群的Lambert机动问题,采用Gim-Alfriend矩阵建立了包含中心轨道根数和摄动项的群卫星的相对运动模型,设计了转移轨道上的卫星群队形协同保持的脉冲控制策略.应用遗传算法对编队卫星群轨道机动问题进行了优化,优化指标分别为卫星群协同变轨过程中总燃料消耗最少或燃料均衡分配最小.分析了群机动过程中燃料消耗的影响因素.算例结果表明遗传算法可以很好地应用于编队卫星群机动问题.

  13. Orbital pseudotumor

    Science.gov (United States)

    ... Goodlick TA, Kay MD, Glaser JS, Tse DT, Chang WJ. Orbital disease and neuro-ophthalmology. In: Tasman ... 423. Review Date 8/20/2016 Updated by: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La ...

  14. Study of the deformation-driving νd5/2 orbital in 6728Ni39 using one-neutron transfer reactions

    Directory of Open Access Journals (Sweden)

    J. Diriken

    2014-09-01

    Full Text Available The νg9/2,d5/2,s1/2 orbitals are assumed to be responsible for the swift onset of collectivity observed in the region below 68Ni. Especially the single-particle energies and strengths of these orbitals are of importance. We studied such properties in the nearby 67Ni nucleus, by performing a (d,p-experiment in inverse kinematics employing a post-accelerated radioactive ion beam (RIB at the REX-ISOLDE facility. The experiment was performed at an energy of 2.95 MeV/u using a combination of the T-REX particle detectors, the Miniball γ-detection array and a newly-developed delayed-correlation technique as to investigate μs-isomers. Angular distributions of the ground state and multiple excited states in 67Ni were obtained and compared with DWBA cross-section calculations, leading to the identification of positive-parity states with substantial νg9/2 (1007 keV and νd5/2 (2207 keV and 3277 keV single-particle strengths up to an excitation energy of 5.8 MeV. 50% of the νd5/2 single-particle strength relative to the νg9/2-orbital is concentrated in and shared between the first two observed 5/2+ levels. A comparison with extended Shell Model calculations and equivalent (3He, d studies in the region around 9040Zr50 highlights similarities for the strength of the negative-parity pf and positive-parity g9/2 state, but differences are observed for the d5/2 single-particle strength.

  15. Foreign body orbital cyst

    DEFF Research Database (Denmark)

    Yazdanfard, Younes; Heegard, Steffen; Fledelius, Hans C.

    2001-01-01

    Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology......Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology...

  16. Orbital Fluid Resupply Assessment

    Science.gov (United States)

    Eberhardt, Ralph N.

    1989-01-01

    Orbital fluid resupply can significantly increase the cost-effectiveness and operational flexibility of spacecraft, satellites, and orbiting platforms and observatories. Reusable tankers are currently being designed for transporting fluids to space. A number of options exist for transporting the fluids and propellant to the space-based user systems. The fluids can be transported to space either in the Shuttle cargo bay or using expendable launch vehicles (ELVs). Resupply can thus be accomplished either from the Shuttle bay, or the tanker can be removed from the Shuttle bay or launched on an ELV and attached to a carrier such as the Orbital Maneuvering Vehicle (OMV) or Orbital Transfer Vehicle (OTV) for transport to the user to be serviced. A third option involves locating the tanker at the space station or an unmanned platform as a quasi-permanent servicing facility or depot which returns to the ground for recycling once its tanks are depleted. Current modular tanker designs for monopropellants, bipropellants, and water for space station propulsion are discussed. Superfluid helium tankers are addressed, including trade-offs in tanker sizes, shapes to fit the range of ELVs currently available, and boil-off losses associated with longer-term (greater than 6-month) space-basing. It is concluded that the mixed fleet approach to on-orbit consumables resupply offers significant advantages to the overall logistics requirements.

  17. Reversible Switching of Redox-Active Molecular Orbitals and Electron Transfer Pathways in Cu(A) Sites of Cytochrome c Oxidase.

    Science.gov (United States)

    Zitare, Ulises; Alvarez-Paggi, Damián; Morgada, Marcos N; Abriata, Luciano A; Vila, Alejandro J; Murgida, Daniel H

    2015-08-10

    The Cu(A) site of cytochrome c oxidase is a redox hub that participates in rapid electron transfer at low driving forces with two redox cofactors in nearly perpendicular orientations. Spectroscopic and electrochemical characterizations performed on first and second-sphere mutants have allowed us to experimentally detect the reversible switching between two alternative electronic states that confer different directionalities to the redox reaction. Specifically, the M160H variant of a native Cu(A) shows a reversible pH transition that allows to functionally probe both states in the same protein species. Alternation between states exerts a dramatic impact on the kinetic redox parameters, thereby suggesting this effect as the mechanism underlying the efficiency and directionality of Cu(A) electron transfer in vivo. These findings may also prove useful for the development of molecular electronics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Charge transfer and orbital reconstruction in the (La{sub 2/3}Sr{sub 1/3}MnO{sub 3}){sub m}/(SrRuO{sub 3}){sub n} superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Kai [Collaborative Innovation Center of Advanced Microstrucutres, Lab of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093 (China); School of Physics and Electronic information, Huaibei Normal University, Huaibei 235000 (China); Zhu, H. P.; Zou, W. Q.; Zhang, F. M.; Wu, X. S., E-mail: xswu@nju.edu.cn [Collaborative Innovation Center of Advanced Microstrucutres, Lab of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093 (China)

    2015-05-14

    The structural, electronic, and magnetic properties of (La{sub 2/3}Sr{sub 1/3}MnO{sub 3}){sub m}/(SrRuO{sub 3}){sub n} superlattices have been investigated based on the first principles calculations. An obvious Jahn-Teller distortion, which depends on m, n, appears in MnO{sub 6} octahedron in the superlattices. The stretch along c-axis of MnO{sub 6} octahedron at the interface lifts the Mn e{sub g} orbital degeneracy, with electrons preferring the lower energy 3z{sup 2}−r{sup 2} to the higher energy x{sup 2}−y{sup 2}. Benefitting from the charge transfer at the interface, the still occupied x{sup 2}−y{sup 2} orbital can mediate a robust in-plane double exchange interaction. La{sub 2/3}Sr{sub 1/3}MnO{sub 3} block is ferromagnetic and metallic, even for the superlattice with m = n = 1.

  19. Modelling the impact of blood flow on the temperature distribution in the human eye and the orbit: fixed heat transfer coefficients versus the Pennes bioheat model versus discrete blood vessels

    Energy Technology Data Exchange (ETDEWEB)

    Flyckt, V M M; Raaymakers, B W; Lagendijk, J J W [Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)

    2006-10-07

    Prediction of the temperature distribution in the eye depends on how the impact of the blood flow is taken into account. Three methods will be compared: a simplified eye anatomy that applies a single heat transfer coefficient to describe all heat transport mechanisms between the sclera and the body core, a detailed eye anatomy in which the blood flow is accounted for either by the bioheat approach, or by including the discrete vasculature in the eye and the orbit. The comparison is done both for rabbit and human anatomies, normo-thermally and when exposed to homogeneous power densities. The first simplified model predicts much higher temperatures than the latter two. It was shown that the eye is very hard to heat when taking physiological perfusion correctly into account. It was concluded that the heat transfer coefficient describing the heat transport from the sclera to the body core reported in the literature for the first simplified model is too low. The bioheat approach is appropriate for a first-order approximation of the temperature distribution in the eye when exposed to a homogeneous power density, but the discrete vasculature down to 0.2 mm in diameter needs to be taken into account when the heterogeneity of the temperature distribution at a mm scale is of interest.

  20. Modelling the impact of blood flow on the temperature distribution in the human eye and the orbit: fixed heat transfer coefficients versus the Pennes bioheat model versus discrete blood vessels

    Science.gov (United States)

    Flyckt, V. M. M.; Raaymakers, B. W.; Lagendijk, J. J. W.

    2006-10-01

    Prediction of the temperature distribution in the eye depends on how the impact of the blood flow is taken into account. Three methods will be compared: a simplified eye anatomy that applies a single heat transfer coefficient to describe all heat transport mechanisms between the sclera and the body core, a detailed eye anatomy in which the blood flow is accounted for either by the bioheat approach, or by including the discrete vasculature in the eye and the orbit. The comparison is done both for rabbit and human anatomies, normo-thermally and when exposed to homogeneous power densities. The first simplified model predicts much higher temperatures than the latter two. It was shown that the eye is very hard to heat when taking physiological perfusion correctly into account. It was concluded that the heat transfer coefficient describing the heat transport from the sclera to the body core reported in the literature for the first simplified model is too low. The bioheat approach is appropriate for a first-order approximation of the temperature distribution in the eye when exposed to a homogeneous power density, but the discrete vasculature down to 0.2 mm in diameter needs to be taken into account when the heterogeneity of the temperature distribution at a mm scale is of interest.

  1. Geometric orbit datum and orbit covers

    Institute of Scientific and Technical Information of China (English)

    梁科; 侯自新

    2001-01-01

    Vogan conjectured that the parabolic induction of orbit data is independent of the choice of the parabolic subgroup. In this paper we first give the parabolic induction of orbit covers, whose relationship with geometric orbit datum is also induced. Hence we show a geometric interpretation of orbit data and finally prove the conjugation for geometric orbit datum using geometric method.

  2. First-principles study of Sr2Ir1-xRhxO4: charge transfer, spin-orbit coupling change, and the metal-insulator transition

    Science.gov (United States)

    Sim, Jae-Hoon; Kim, Heung-Sik; Han, Myung Joon

    2015-03-01

    Using first-principles density functional theory (DFT) calculations, we investigated the electronic structure of Rh-doped iridate, Sr2Ir1-xRhxO4 for which the doping (x) dependent metal-insulator transition (MIT) has been reported experimentally and the controversial discussion developed regarding the origin of this transition. Our DFT+U calculation shows that the value of remains largely intact over the entire doping range considered here (x = 0 . 0 , 0 . 125 , 0 . 25 , 0 . 50 , 0 . 75 , and 1 . 0) in good agreement with the branching ratio measured by x-ray absorption spectroscopy. Also contrary to a previous picture to explain MIT based on the charge transfer between the transition-metal sites, our calculation clearly shows that those sites remain basically isoelectronic while the impurity bands of predominantly rhodium character are introduced near the Fermi level. As the doping increases, this impurity band overlaps with lower Hubbard band of iridium, leading to metal-insulator transition. The results will be discussed with comparison to the case of Ru doping. Computational resources were suported by The National Institute of Supercomputing and Networking/Korea Institute of Science and Technology Information with supercomputing resources including technical spport (Grant No. KSC-2013-C2-23).

  3. Halo orbit to science orbit captures at planetary moons

    Science.gov (United States)

    Bokelmann, Kevin A.; Russell, Ryan P.

    2017-05-01

    Ballisticly connecting halo orbits to science orbits in the circular-restricted three-body problem is investigated. Two classes of terminal science orbits are considered: low-altitude, tight orbits that are deep in the gravity well of the secondary body, and high-altitude, loose orbits that are strongly perturbed by the gravity of the primary body. General analytic expressions are developed to provide a minimum bound on impulse cost in both the circular restricted and the Hill's approximations. The equations are applied to a broad range of planetary moons, providing a mission design reference. Systematic grid search methods are developed to numerically find feasible transfers from halo orbits at Europa, confirming the analytical lower bound formulas. The two-impulse capture options in the case of Europa reveal a diverse set of potential solutions. Tight captures result in maneuver costs of 425-550 m/s while loose captures are found with costs as low as 30 m/s. The terminal orbits are verified to avoid escape or impact for at least 45 days.

  4. Molecular Orbital and Density Functional Study of the Formation, Charge Transfer, Bonding and the Conformational Isomerism of the Boron Trifluoride (BF3 and Ammonia (NH3 Donor-Acceptor Complex

    Directory of Open Access Journals (Sweden)

    Dulal C. Ghosh

    2004-09-01

    Full Text Available The formation of the F3B–NH3 supermolecule by chemical interaction of its fragment parts, BF3 and NH3, and the dynamics of internal rotation about the ‘B–N’ bond have been studied in terms of parameters provided by the molecular orbital and density functional theories. It is found that the pairs of frontier orbitals of the interacting fragments have matching symmetry and are involved in the charge transfer interaction. The donation process stems from the HOMO of the donor into the LUMO of the acceptor and simultaneously, back donation stems from the HOMO of acceptor into the LUMO of the donor. The density functional computation of chemical activation in the donor and acceptor fragments, associated with the physical process of structural reorganization just prior to the event of chemical reaction, indicates that BF3 becomes more acidic and NH3 becomes more basic, compared to their separate equilibrium states. Theoretically it is observed that the chemical reaction event of the formation of the supermolecule from its fragment parts is in accordance with the chemical potential equalization principle of the density functional theory and the electronegativity equalization principle of Sanderson. The energetics of the chemical reaction, the magnitude of the net charge transfer and the energy of the newly formed bond are quite consistent, both internally and with the principle of maximum hardness, PMH. The dynamics of the internal rotation of one part with respect to the other part of the supermolecule about the ‘B–N’ bond mimics the pattern of the conformational isomerism of the isostructural ethane molecule. It is also observed that the dynamics and evolution of molecular conformations as a function of dihedral angles is also in accordance with the principle of maximum hardness, PMH. Quite consistent with spectroscopic predictions, the height of the molecule

  5. 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.

  6. 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.

  7. Inflammation of the Orbit

    Science.gov (United States)

    ... Eye Exams, Study Finds Additional Content Medical News Inflammation of the Orbit (Inflammatory Orbital Pseudotumor) By James ... Introduction to Eye Socket Disorders Cavernous Sinus Thrombosis Inflammation of the Orbit Orbital Cellulitis Preseptal Cellulitis Tumors ...

  8. Imaging of Orbital Infections

    OpenAIRE

    Seyed Hassan Mostafavi

    2010-01-01

    Preseptal and orbital cellulitis occur more commonly in children than adults. The history and physical examination are crucial in distinguishing between preseptal and orbital cellulitis. The orbital septum delineates the anterior eyelid soft tissues from the orbital soft tissue. Infections anterior to the orbital septum are classified as preseptal cellulitis and those posterior to the orbital septum are termed orbital cellulitis. "nRecognition of orbital involvement is important not only...

  9. Orbital liposarcoma.

    Science.gov (United States)

    Borbolla-Pertierra, A M; Morales-Baños, D R; Martínez-Nava, L R; Garrido-Sánchez, G A; López-Hernández, C M; Velasco-Ramos, P

    2017-02-01

    The case is presented of a 46-year-old male with right eye proptosis and conjunctival hyperaemia, of 18 months onset. A well-defined intraconal mass was found in the computed tomography. In magnetic resonance this was hypo-intense on T1, enhanced with gadolinium and hyperintense on T2. Excisional biopsy was performed, which was reported as a well-differentiated liposarcoma in the histopathology study. Liposarcoma is a malignant adipose tissue tumour. It is very rare in the orbit, with 5 histological types, the most common being myxoid. The treatment of choice is wide surgical excision and may be accompanied with radiotherapy. As it is an infiltrative tumour, It has a high rate of recurrence. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  10. Impulsive orbit control for spacecraft around asteroid

    Institute of Scientific and Technical Information of China (English)

    崔祜涛; 崔平远; 栾恩杰

    2003-01-01

    An impulse feedback control law to change the mean orbit elements of spacecraft around asteroid is presented. First, the mean orbit elements are transferred to the osculating orbit elements at the burning time.Then, the feedback control law based on Gauss' s perturbation equations of motion is given. And the impulse control for targeting from the higher circulation orbit to the specified periapsis is developed. Finally, the numerical simulation is performed and the simulation results show that the presented impulse control law is effective.

  11. Small Orbits

    CERN Document Server

    Borsten, L; Ferrara, S; Marrani, A; Rubens, W

    2012-01-01

    We study both the "large" and "small" U-duality charge orbits of extremal black holes appearing in D = 5 and D = 4 Maxwell-Einstein supergravity theories with symmetric scalar manifolds. We exploit a formalism based on cubic Jordan algebras and their associated Freudenthal triple systems, in order to derive the minimal charge representatives, their stabilizers and the associated "moduli spaces". After recalling N = 8 maximal supergravity, we consider N = 2 and N = 4 theories coupled to an arbitrary number of vector multiplets, as well as N = 2 magic, STU, ST^2 and T^3 models. While the STU model may be considered as part of the general N = 2 sequence, albeit with an additional triality symmetry, the ST^2 and T^3 models demand a separate treatment, since their representative Jordan algebras are Euclidean or only admit non-zero elements of rank 3, respectively. Finally, we also consider minimally coupled N = 2, matter coupled N = 3, and "pure" N = 5 theories.

  12. Updates in Orbital Tumors

    Institute of Scientific and Technical Information of China (English)

    Nila; F.Moeloek

    1993-01-01

    Orbital anatomy, the clinical features of orbital tumors, the recent development of the diagnosis and management of orbital tumors were described. The incidence of orbital tumors in Dr. Cipto Mangunkusumo Hospital in the past years were introduced. The principle of management of orbital tumors and their prognosis were discussed.

  13. Electronic structure interpolation via atomic orbitals.

    Science.gov (United States)

    Chen, Mohan; Guo, G-C; He, Lixin

    2011-08-17

    We present an efficient scheme for accurate electronic structure interpolation based on systematically improvable optimized atomic orbitals. The atomic orbitals are generated by minimizing the spillage value between the atomic basis calculations and the converged plane wave basis calculations on some coarse k-point grid. They are then used to calculate the band structure of the full Brillouin zone using the linear combination of atomic orbitals algorithms. We find that usually 16-25 orbitals per atom can give an accuracy of about 10 meV compared to the full ab initio calculations, and the accuracy can be systematically improved by using more atomic orbitals. The scheme is easy to implement and robust, and works equally well for metallic systems and systems with complicated band structures. Furthermore, the atomic orbitals have much better transferability than Shirley's basis and Wannier functions, which is very useful for perturbation calculations.

  14. Imaging of Orbital Infections

    Directory of Open Access Journals (Sweden)

    Seyed Hassan Mostafavi

    2010-05-01

    Full Text Available Preseptal and orbital cellulitis occur more commonly in children than adults. The history and physical examination are crucial in distinguishing between preseptal and orbital cellulitis. The orbital septum delineates the anterior eyelid soft tissues from the orbital soft tissue. Infections anterior to the orbital septum are classified as preseptal cellulitis and those posterior to the orbital septum are termed orbital cellulitis. "nRecognition of orbital involvement is important not only because of the threatened vision loss associated with orbital cellulitis but also because of the potential for central nervous system complications including cavernous sinus thrombosis, meningitis, and death. "nOrbital imaging should be obtained in all patients suspected of having orbital cellulitis. CT is preferred to MR imaging, as the orbital tissues have high con-trast and the bone can be well visualized. Orbital CT scanning allows localization of the disease process to the preseptal area, the extraconal or intraconal fat, or the subperiosteal space. Axial CT views allow evaluation of the medial orbit and ethmoid sinuses, whereas coronal scans image the orbital roof and floor and the frontal and maxillary sinuses. If direct coronal imaging is not possible, reconstruction of thin axial cuts may help the assessment of the orbital roof and floor. Potential sources of orbital cellulitis such as sinusitis, dental infection, and facial cellulitis are often detectable on CT imaging. "nIn this presentation, the imaging considerations of the orbital infections; including imaging differentiation criteria of all types of orbital infections are reviewed.

  15. Preseptal Cellulitis, Orbital Cellulitis, Orbital Abscess

    OpenAIRE

    Rana Altan Yaycıoğlu

    2012-01-01

    Patients with orbital infections present to our clinic usually with unilateral pain, hyperemia, and edema of the eyelids. The differentiation between preseptal and orbital cellulitis is utmost important in that the second requires hospitalization. Since in orbital cellulitis, the tissues posterior to the orbital septum are involved, signs such as conjunctival chemosis, limited eye movement, decreased vision, as well as afferent pupil defect secondary to optic nerve involvement may al...

  16. Three Orbital Burns to Molniya Orbit via Shuttle Centaur G Upper Stage

    Science.gov (United States)

    Williams, Craig H.

    2014-01-01

    An unclassified analytical trajectory design, performance, and mission study was done for the 1982-86 joint NASA-USAF Shuttle/Centaur G upper stage development program to send performance-demanding payloads to high orbits such as Molniya using an unconventional orbit transfer. This optimized three orbital burn transfer to Molniya orbit was compared to the then-baselined two burn transfer. The results of the three dimensional trajectory optimization performed include powered phase steering data and coast phase orbital element data. Time derivatives of the orbital elements as functions of thrust components were evaluated and used to explain the optimization's solution. Vehicle performance as a function of parking orbit inclination was given. Performance and orbital element data was provided for launch windows as functions of launch time. Ground track data was given for all burns and coasts including variation within the launch window. It was found that a Centaur with fully loaded propellant tanks could be flown from a 37deg inclination low Earth parking orbit and achieve Molniya orbit with comparable performance to the baselined transfer which started from a 57deg inclined orbit: 9,545 lb vs. 9,552 lb of separated spacecraft weight respectively. There was a significant reduction in the need for propellant launch time reserve for a one hour window: only 78 lb for the three burn transfer vs. 320 lb for the two burn transfer. Conversely, this also meant that longer launch windows over more orbital revolutions could be done for the same amount of propellant reserve. There was no practical difference in ground tracking station or airborne assets needed to secure telemetric data, even though the geometric locations of the burns varied considerably. There was a significant adverse increase in total mission elapsed time for the three vs. two burn transfer (12 vs. 11/4 hrs), but could be accommodated by modest modifications to Centaur systems. Future applications were

  17. Three Orbital Burns to Molniya Orbit Via Shuttle_Centaur G Upper Stage

    Science.gov (United States)

    Williams, Craig H.

    2015-01-01

    An unclassified analytical trajectory design, performance, and mission study was done for the 1982 to 1986 joint National Aeronautics and Space Administration (NASA)-United States Air Force (USAF) Shuttle/Centaur G upper stage development program to send performance-demanding payloads to high orbits such as Molniya using an unconventional orbit transfer. This optimized three orbital burn transfer to Molniya orbit was compared to the then-baselined two burn transfer. The results of the three dimensional trajectory optimization performed include powered phase steering data and coast phase orbital element data. Time derivatives of the orbital elements as functions of thrust components were evaluated and used to explain the optimization's solution. Vehicle performance as a function of parking orbit inclination was given. Performance and orbital element data was provided for launch windows as functions of launch time. Ground track data was given for all burns and coasts including variation within the launch window. It was found that a Centaur with fully loaded propellant tanks could be flown from a 37 deg inclination low Earth parking orbit and achieve Molniya orbit with comparable performance to the baselined transfer which started from a 57 deg inclined orbit: 9,545 versus 9,552 lb of separated spacecraft weight, respectively. There was a significant reduction in the need for propellant launch time reserve for a 1 hr window: only 78 lb for the three burn transfer versus 320 lb for the two burn transfer. Conversely, this also meant that longer launch windows over more orbital revolutions could be done for the same amount of propellant reserve. There was no practical difference in ground tracking station or airborne assets needed to secure telemetric data, even though the geometric locations of the burns varied considerably. There was a significant adverse increase in total mission elapsed time for the three versus two burn transfer (12 vs. 1-1/4 hr), but could be

  18. Bilateral orbital cavernous haemangiomas.

    OpenAIRE

    Fries, P D; Char, D. H.

    1988-01-01

    Simultaneous bilateral orbital lesions are rare. The differential diagnosis includes orbital pseudotumour, metastasis, leukaemia, lymphoma, Wegener's granulomatosis, and neurofibromatosis. We report what we believe to be the first case of bilateral orbital cavernous haemangiomas.

  19. Orbital dystopia due to orbital roof defect.

    Science.gov (United States)

    Rha, Eun Young; Joo, Hong Sil; Byeon, Jun Hee

    2013-01-01

    We performed a retrospective review of patients who presented with delayed dystopia as a consequence of an orbital roof defect due to fractures and nontraumatic causes to search for a correlation between orbital roof defect size and surgical indications for the treatment thereof. Retrospective analyses were performed in 7 patients, all of whom presented with delayed dystopia due to orbital roof defects, between January 2001 and June 2011. The causes of orbital roof defects were displaced orbital roof fractures (5 cases), tumor (1 case), and congenital sphenoid dysplasia (1 case). All 7 patients had initially been treated conservatively and later presented with significant dystopia. The sizes of the defects were calculated on computed tomographic scans. Among the 7 patients, aspiration of cerebrospinal fluid, which caused ocular symptoms, in 1 patient with minimal displaced orbital roof and reconstruction with calvarial bone, titanium micromesh, or Medpor in 6 other patients were performed. The minimal size of the orbital roof in patients who underwent orbital roof reconstruction was 1.2 cm (defect height) x 1.0 cm (defect length), 0.94 cm(2). For all patients with orbital dystopia, displacement of the globe was corrected without any complications, regardless of whether the patient was evaluated grossly or by radiology. In this retrospective study, continuous monitoring of clinical signs and active surgical management should be considered for cases in which an orbital roof defect is detected, even if no definite symptoms are noted, to prevent delayed sequelae.

  20. The one-electron description of excited states: Natural excitation orbitals of density matrix theory and Kohn-Sham orbitals of density functional theory as ideal orbitals

    Science.gov (United States)

    van Meer, R.; Gritsenko, O. V.; Baerends, E. J.

    2015-10-01

    Linear response density matrix functional theory has been shown to solve the main problems of time-dependent density functional theory (deficient in case of double, charge transfer and bond breaking excitations). However, the natural orbitals preclude the description of excitations as (approximately) simple orbital-to-orbital transitions: many weakly occupied 'virtual' natural orbitals are required to describe the excitations. Kohn-Sham orbitals on the other hand afford for many excitations such a simple orbital description. In this communication we show that a transformation of the set of weakly occupied NOs can be defined such that the resulting natural excitation orbitals (NEOs) restore the single orbital transition structure for excitations generated by the linear response DMFT formalism.

  1. A Design Method for Earth-Moon Halo Orbit Transfer Trajectory Under Different Constraints to Moon Gravity-Assisted Maneuvers%不同月球借力约束下的地月 Halo 轨道转移轨道设计

    Institute of Scientific and Technical Information of China (English)

    张景瑞; 曾豪; 李明涛

    2016-01-01

    To design low-energy Earth-Moon L2 Halo orbit transfer trajectory for different mission requirements,a deep research on the influence of different constraints to the moon gravity-assisted maneuvers and Halo orbit insertion (HOI) points with different amplitudes on time of flight and fuel consumption is made,and a selection strategy for HOI points is proposed in this paper.Firstly,combined with mission requirements and effects of the moon gravity,different constraints are applied to the moon gravity-assisted maneuvers.Stable manifold of Halo orbit is adjusted through differential correction algorithm and the transfer trajectory from moon to Halo orbit is designed.Then,in consideration of orbit altitude ,orbit inclination,right ascension of ascending node and track angle at the same time,the hybrid optimization strategy combined genetic algorithm with differential correction algorithm is adopted to study Earth-Moon Halo orbit transfer trajectories with optimal fuel consumption.At last,the influence of moon gravity-assisted altitude and azimuth as well as different HOI points on flight time and fuel consumption of transfer trajectories is respectively analyzed,which has reference value for design and application of Earth-Moon Halo orbit transfer trajectories.%针对地月系 L2点不同任务需求下的低耗能转移轨道设计问题,基于不变流形理论与混合优化技术,深入研究了不同月球借力约束与不同幅值 Halo 轨道的入轨点(简称 HOI 点)对转移轨道飞行时间与燃料消耗的影响,给出了 HOI 点选择策略。首先结合任务要求并考虑月球引力影响,在月球借力点施加不同约束条件,通过微分修正算法调整 Halo 轨道的稳定流形,设计月球到 Halo 轨道的转移轨道。采用遗传算法与微分修正算法相结合的混合优化策略,在同时考虑地球停泊轨道高度、倾角、升交点赤经与航迹角等多约束条件下,对燃料最优的地月转

  2. Orbital Energy-Based Reaction Analysis of SN2 Reactions

    Directory of Open Access Journals (Sweden)

    Takao Tsuneda

    2016-07-01

    Full Text Available An orbital energy-based reaction analysis theory is presented as an extension of the orbital-based conceptual density functional theory. In the orbital energy-based theory, the orbitals contributing to reactions are interpreted to be valence orbitals giving the largest orbital energy variation from reactants to products. Reactions are taken to be electron transfer-driven when they provide small variations for the gaps between the contributing occupied and unoccupied orbital energies on the intrinsic reaction coordinates in the initial processes. The orbital energy-based theory is then applied to the calculations of several S N2 reactions. Using a reaction path search method, the Cl− + CH3I → ClCH3 + I− reaction, for which another reaction path called “roundabout path” is proposed, is found to have a precursor process similar to the roundabout path just before this SN2 reaction process. The orbital energy-based theory indicates that this precursor process is obviously driven by structural change, while the successor SN2 reaction proceeds through electron transfer between the contributing orbitals. Comparing the calculated results of the SN2 reactions in gas phase and in aqueous solution shows that the contributing orbitals significantly depend on solvent effects and these orbitals can be correctly determined by this theory.

  3. Preseptal Cellulitis, Orbital Cellulitis, Orbital Abscess

    Directory of Open Access Journals (Sweden)

    Rana Altan Yaycıoğlu

    2012-12-01

    Full Text Available Patients with orbital infections present to our clinic usually with unilateral pain, hyperemia, and edema of the eyelids. The differentiation between preseptal and orbital cellulitis is utmost important in that the second requires hospitalization. Since in orbital cellulitis, the tissues posterior to the orbital septum are involved, signs such as conjunctival chemosis, limited eye movement, decreased vision, as well as afferent pupil defect secondary to optic nerve involvement may also be observed. Prompt intravenous antibiotic treatment should be started, and surgical drainage may be performed if patient shows failure to improve in 48 hours despite optimal management. Without treatment, the clinical course may progress to subperiosteal or orbital abscess, and even to cavernous sinus thrombosis. (Turk J Ophthalmol 2012; 42: Supplement 52-6

  4. Orbit design for the Laser Interferometer Space Antenna (LISA)

    Institute of Scientific and Technical Information of China (English)

    Gerhard; HEINZEL; Albrecht; RDIGER

    2010-01-01

    The Laser Interferometer Space Antenna (LISA) is a joint ESA-NASA mission for detecting low-frequency gravitational waves in the frequency range from 0.1 mHz to 1 Hz, by using accurate laser interferometry between three spacecrafts, which will be launched around 2018 and one year later reach their operational orbits around the Sun. In order to operate successfully, it is crucial for the constellation of the three spacecrafts to have extremely high stability. Based on the study of operational orbits for a 2015 launch, we design the operational orbits of beginning epoch on 2019-03-01, and introduce the method of orbit design and optimization. We design the orbits of the transfer from Earth to the operational orbits, including launch phase and separation phase; furthermore, the relationship between energy requirement and flight time of these two orbit phases is investigated. Finally, an example of the whole orbit design is presented.

  5. Lunar Orbiter Photo Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Orbiter Photo Gallery is an extensive collection of over 2,600 high- and moderate-resolution photographs produced by all five of the Lunar Orbiter...

  6. ASC Champ Orbit Model

    DEFF Research Database (Denmark)

    Riis, Troels; Jørgensen, John Leif

    1999-01-01

    This documents describes a test of the implementation of the ASC orbit model for the Champ satellite.......This documents describes a test of the implementation of the ASC orbit model for the Champ satellite....

  7. Polygons in billiard orbits

    CERN Document Server

    Don, Henk

    2011-01-01

    We study the geometry of billiard orbits on rectangular billiards. A truncated billiard orbit induces a partition of the rectangle into polygons. We prove that thirteen is a sharp upper bound for the number of different areas of these polygons.

  8. Traumatic transconjunctival orbital emphysema.

    OpenAIRE

    Stroh, E M; Finger, P T

    1990-01-01

    Orbital emphysema can be produced by trans-conjunctival migration of air from a high pressure airgun. In an industrial accident an 8 mm conjunctival laceration was produced in the superior fornix which acted as a portal of entry for air into the subconjunctival, subcutaneous, and retrobulbar spaces. Computed tomography revealed no evidence of orbital fracture and showed that traumatic orbital emphysema occurred without a broken orbital bone.

  9. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  10. Painless orbital myositis

    Directory of Open Access Journals (Sweden)

    Rahul T Chakor

    2012-01-01

    Full Text Available Idiopathic orbital inflammation is the third most common orbital disease, following Graves orbitopathy and lymphoproliferative diseases. We present a 11 year old girl with 15 days history of painless diplopia. There was no history of fluctuation of symptoms, drooping of eye lids or diminished vision. She had near total restricted extra-ocular movements and mild proptosis of the right eye. There was no conjunctival injection, chemosis, or bulb pain. There was no eyelid retraction or lid lag. Rest of the neurological examination was unremarkable.Erythrocyte sedimentation rate was raised with eosinophilia. Antinuclear antibodies were positive. Liver, renal and thyroid functions were normal. Antithyroid, double stranded deoxyribonucleic acid and acetylcholine receptor antibodies were negative. Repetitive nerve stimulation was negative. Magnetic resonance imaging (MRI of the orbit was typical of orbital myositis. The patient responded to oral steroids. Orbital myositis can present as painless diplopia. MRI of orbit is diagnostic in orbital myositis.

  11. 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 

  12. Orbit Response Measurements at the SPS

    CERN Document Server

    Wenninger, J

    2004-01-01

    The optics of the SPS ring and the TT40 transfer line have been analyzed using the closed orbit (respectively trajectory) response to controlled corrector magnet deflections. A large amount of information on the machine model, beam position monitor quality and orbit corrector calibrations can be extracted from te response data. The data was analyzed with the LOCO fit program that was adapted to the SPS machine model. A large amount of data was collected on the SPS ring, and the modelling was tested under a number of different conditions. The SPS ring data showed that a significant number of horizontal SPS orbit correctors do not provide the nominal kick strength and are damaged at the level of the magnet coil. This note describes the experience that has been gained at the SPS, the information that could be extracted from orbit data and some of the limitations of the analysis procedure in the context of the SPS.

  13. Orbit design for a space ambulance vehicle

    Science.gov (United States)

    Nelson, Walter C.

    A number of rendezvous maneuvers between space stations in geocentric orbits at altitudes ranging between 200 km and geosynchronous altitude are examined. Minimum time to complete rendezvous is studied for purposes of expediting crew patient transfer to an orbiting medical base station (MBS) for the stabilization of trauma and definitive care. The vehicle to be used for the crew patient transfer to the MBS is the space ambulance vehicle (SAV). The SAV is assumed to use two velocity impulses to complete rendezvous maneuvers between an SS and the MBS: an accelerating impulse when departing the SS and a second decelerating impulse prior to docking with the MBS. Recommendations are made concerning the planning of space operations which will reduce both time and propulsive energy for rendezvous maneuvers. It is suggested that throttleable engines be used when transferring a crew patient whose trauma could be exacerbated by excessive acceleration of the carrier vehicle.

  14. 太阳帆航天器地球逃逸轨道解析最优控制律%Solar sail analytical optimal control law for earth escape transfer orbit

    Institute of Scientific and Technical Information of China (English)

    史晓宁; 李立涛; 崔乃刚

    2013-01-01

    针对太阳帆航天器地球逃逸轨道控制问题,给出一种新的解析最优控制律.该控制律可使航天器在逃逸过程中轨道能量变化速率最大,从而保证逃逸时间最短.考虑到地球逃逸轨道形状,引入改进春分点轨道根数对航天器运动学方程进行描述,并给出了地球逃逸轨道最优控制律的推导过程.仿真分析表明,该控制律计算速度较快,而且可以根据航天器状态实时计算姿态控制角,因此比较适用于未来太阳帆航天器在轨自主控制系统.%Aiming at orbit control problem for escaping the earth with solar sail, a new analytical optimal control law is presented. This approach maximizes the instantaneous rate of the increase of the total orbital energy in the process of escaping the earth, so as to ensure the shortest escape time. The equations of motion for the trajectory are expressed in modified equinoctial orbital elements, which are well behaved as the trajectory going from elliptic to hyperbolic during escape. Furthermore, the derivation of escaping the earth optimal control law is given. Simulation analysis shows that the control law has higher computational speed, and can real-timely calculate the attitude control angle according to the state of spacecraft by the simulation analysis, hence the control law is suitable for the application in future on-orbit solar sail autonomous control system.

  15. Orbital Maneuvering Vehicle (OMV) missions applications and systems requirements

    Science.gov (United States)

    Huber, W. G.; Cramblit, D. C.

    The routine delivery of large payloads to low earth orbit has become a reality with the Space Transportation System (STS). However, once earth orbit has been achieved, orbit transfer operations represent an inefficient use of the Space Shuttle. The Orbital Maneuvering Vehicle (OMV) will add a new and needed dimension to STS capabilities. Utilized in a reusable manner, the OMV is needed to deliver and retrieve satellites to and from orbital altitudes or inclinations beyond the practical limits of the Space Shuttle and to support basic Space Station activities. The initial OMV must also be designed to permit the addition of future mission kits to support the servicing, module changeout, or refueling of satellites in Low Earth Orbit (LEO) and Geostationary Earth Orbit (GEO), and the retrieval and deorbit of space debris. This paper addresses the mission needs along with the resulting performance implications, design requirements and operational capabilities imposed on the OMV planned for use in the late 1980s.

  16. Orbit Maneuver of Spinning Tether via Tidal Force

    CERN Document Server

    Baoyin, Hexi; Li, Junfeng

    2014-01-01

    Recently, the spinning tethered system is regarded as a typical and fundamental space structure attracting great interest of the aerospace engineers, and has been discussed primarily for specific space missions in past decades, including on-orbit capture and propellantless orbit transfer etc. The present work studies the dynamical behaviours of a fast spinning tethered binary system under central gravitational field, and derives principles of the basic laws of orbital maneuver. Considering the characteristics of coupled librational and orbital motions, an averaging method is introduced to deal with the slow-fast system equation, thus a definite equivalent model is derived. The general orbit motion is completely determined analytically, including the orbit geometry, periodicity, conversations and moving region etc. Since the possibility of orbit control using tether reaction has been proved by previous studies, special attention is paid to the transportation mode of angular momentum and mechanical energy betwe...

  17. Alternative paths to Earth-Moon transfer

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The planar, circular, restricted three-body problem predicts the existence of periodic orbits around the Lagrangian equilibrium point L1. Considering the Earth-lunar-probe system, some of these orbits pass very close to the surfaces of the Earth and the Moon. These characteristics make it possible for these orbits, in spite of their instability, to be used in transfer maneuvers between Earth and lunar parking orbits. The main goal of this paper is to explore this scenario, adopting a more complex and realistic dynamical system, the four-body problem Sun-Earth-Moon-probe. We defined and investigated a set of paths, derived from the orbits around L1, which are capable of achieving transfer between low-altitude Earth (LEO and lunar orbits, including high-inclination lunar orbits, at a low cost and with flight time between 13 and 15 days.

  18. Periodic orbits around areostationary points in the Martian gravity field

    Science.gov (United States)

    Liu, Xiao-Dong; Baoyin, Hexi; Ma, Xing-Rui

    2012-05-01

    This study investigates the problem of areostationary orbits around Mars in three-dimensional space. Areostationary orbits are expected to be used to establish a future telecommunication network for the exploration of Mars. However, no artificial satellites have been placed in these orbits thus far. The characteristics of the Martian gravity field are presented, and areostationary points and their linear stability are calculated. By taking linearized solutions in the planar case as the initial guesses and utilizing the Levenberg-Marquardt method, families of periodic orbits around areostationary points are shown to exist. Short-period orbits and long-period orbits are found around linearly stable areostationary points, but only short-period orbits are found around unstable areostationary points. Vertical periodic orbits around both linearly stable and unstable areostationary points are also examined. Satellites in these periodic orbits could depart from areostationary points by a few degrees in longitude, which would facilitate observation of the Martian topography. Based on the eigenvalues of the monodromy matrix, the evolution of the stability index of periodic orbits is determined. Finally, heteroclinic orbits connecting the two unstable areostationary points are found, providing the possibility for orbital transfer with minimal energy consumption.

  19. Periodic orbits around areostationary points in the Martian gravity field

    Institute of Scientific and Technical Information of China (English)

    Xiao-Dong Liu; Hexi Baoyin; Xing-Rui Ma

    2012-01-01

    This study investigates the problem of areostationary orbits around Mars in three-dimensional space.Areostationary orbits are expected to be used to establish a future telecommunication network for the exploration of Mars.However,no artificial satellites have been placed in these orbits thus far.The characteristics of the Martian gravity field are presented,and areostationary points and their linear stability are calculated.By taking linearized solutions in the planar case as the initial guesses and utilizing the Levenberg-Marquardt method,families of periodic orbits around areostationary points are shown to exist.Short-period orbits and long-period orbits are found around linearly stable areostationary points,but only short-period orbits are found around unstable areostationary points.Vertical periodic orbits around both linearly stable and unstable areostationary points are also examined.Satellites in these periodic orbits could depart from areostationary points by a few degrees in longitude,which would facilitate observation of the Martian topography.Based on the eigenvalues of the monodromy matrix,the evolution of the stability index of periodic orbits is determined.Finally,heteroclinic orbits connecting the two unstable areostationary points are found,providing the possibility for orbital transfer with minimal energy consumption.

  20. The Exoplanet Orbit Database

    CERN Document Server

    Wright, Jason T; Marcy, Geoffrey W; Han, Eunkyu; Feng, Ying; Johnson, John Asher; Howard, Andrew W; Valenti, Jeff A; Anderson, Jay; Piskunov, Nikolai

    2010-01-01

    We present a database of well determined orbital parameters of exoplanets. This database comprises spectroscopic orbital elements measured for 421 planets orbiting 357 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The database is available in a searchable, filterable, and sortable form on the Web at http://exoplanets.org through the Exoplanets Data Explorer Table, and the data can be plotted and explored through the Exoplanets Data Explorer Plotter. We use the Data Explorer to generate publication-ready plots giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the selection different biase...

  1. Preseptal and orbital cellulitis

    OpenAIRE

    Emine Akçay; Gamze Dereli Can; Nurullah Çağıl

    2014-01-01

    Preseptal cellulitis (PC) is defined as an inflammation of the eyelid and surrounding skin, whereas orbital cellulitis (OC) is an inflammation of the posterior septum of the eyelid affecting the orbit and its contents. Periorbital tissues may become infected as a result of trauma (including insect bites) or primary bacteremia. Orbital cellulitis generally occurs as a complication of sinusitis. The most commonly isolated organisms are Staphylococcus aureus, Streptococcus pneumoniae, S. epid...

  2. Orbital inflammation: Corticosteroids first.

    Science.gov (United States)

    Dagi Glass, Lora R; Freitag, Suzanne K

    2016-01-01

    Orbital inflammation is common, and may affect all ages and both genders. By combining a thorough history and physical examination, targeted ancillary laboratory testing and imaging, a presumptive diagnosis can often be made. Nearly all orbital inflammatory pathology can be empirically treated with corticosteroids, thus obviating the need for histopathologic diagnosis prior to initiation of therapy. In addition, corticosteroids may be effective in treating concurrent systemic disease. Unless orbital inflammation responds atypically or incompletely, patients can be spared biopsy.

  3. Geometric orbit datum and orbit covers

    Institute of Scientific and Technical Information of China (English)

    LIANG; Ke(

    2001-01-01

    [1]Vogan, D. , Dixmier algebras, sheets and representation theory (in Actes du colloque en I' honneur de Jacques Dixmier),Progress in Math. 92, Boston: Birkhauser Verlag, 1990, 333-397.[2]McGovern, W., Dixmier Algebras and Orbit Method, Operator Algebras, Unitary Representations and Invariant Theory,Boston: Birkhauser, 1990, 397-416.[3]Liang, K. , Parabolic inductions of nilpotent geometric orbit datum, Chinese Science Bulletin (in Chinese) , 1996, 41 (23):2116-2118.[4]Vogan, D., Representations of Real Reductive Lie Groups, Boston-Basel-Stuttgart: Birkhauser, 1981.[5]Lustig, G., Spaltenstein, N., Induced unipotent class, J. London Math. Soc., 1997, 19. 41-52.[6]Collingwood, D. H. , McGovern, W. M. , Nilpotent Orbits in Semisimple Lie Algebras, New York: Van Nostremt Reinhold,1993.

  4. Family of Orbiters

    Science.gov (United States)

    2008-01-01

    This image shows the paths of three spacecraft currently in orbit around Mars, as well as the path by which NASA's Phoenix Mars Lander will approach and land on the planet. The t-shaped crosses show where the orbiters will be when Phoenix enters the atmosphere, while the x-shaped crosses show their location at landing time. All three orbiters, NASA's Mars Reconnaissance Orbiter, NASA's Mars Odyssey and the European Space Agency's Mars Express, will be monitoring Phoenix during the final steps of its journey to the Red Planet. Phoenix will land just south of Mars's north polar ice cap.

  5. Orbital engineering in symmetry-breaking polar heterostructures.

    Science.gov (United States)

    Disa, Ankit S; Kumah, Divine P; Malashevich, Andrei; Chen, Hanghui; Arena, Dario A; Specht, Eliot D; Ismail-Beigi, Sohrab; Walker, F J; Ahn, Charles H

    2015-01-16

    We experimentally demonstrate a novel approach to substantially modify orbital occupations and symmetries in electronically correlated oxides. In contrast to methods using strain or confinement, this orbital tuning is achieved by exploiting charge transfer and inversion symmetry breaking using atomically layered heterostructures. We illustrate the technique in the LaTiO_{3}-LaNiO_{3}-LaAlO_{3} system; a combination of x-ray absorption spectroscopy and ab initio theory reveals electron transfer and concomitant polar fields, resulting in a ∼50% change in the occupation of Ni d orbitals. This change is sufficiently large to remove the orbital degeneracy of bulk LaNiO_{3} and creates an electronic configuration approaching a single-band Fermi surface. Furthermore, we theoretically show that such three-component heterostructuring is robust and tunable by choice of insulator in the heterostructure, providing a general method for engineering orbital configurations and designing novel electronic systems.

  6. 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.

  7. Patterns of orbital disorders

    Directory of Open Access Journals (Sweden)

    Balasubramanian Thiagarajan

    2014-08-01

    Full Text Available This article discusses various patterns of presentations of orbital lesions. Since this article has been authored by an otolaryngologist, the entire concept has been viewed from otolaryngologist's angle. With the advent of nasal endoscope trans nasal access to orbit is becoming the order of the day. Major advantage being that external skin incision is avoided.

  8. LUNISOLAR INVARIANT RELATIVE ORBITS

    OpenAIRE

    Walid Ali Rahoma

    2013-01-01

    The present study deal with constructing an analytical model within Hamiltonian formulation to design invariant relative orbits due to the perturbation of J2 and the lunisolar attraction. To fade the secular drift separation over the time between two neighboring orbits, two second order conditions that guarantee that drift are derived and enforced to be equal.

  9. Reticulohistiocytoma of the Orbit

    Science.gov (United States)

    Weissman, Heather M.; Hayek, Brent R.; Grossniklaus, Hans E.

    2015-01-01

    Reticulohistiocytoma is a rare, benign histiocytic proliferation of the skin or soft tissue. While ocular involvement has been documented in the past, there have been no previously reported cases of reticulohistiocytoma of the orbit. In this report, the authors describe a reticulohistiocytoma of the orbit in a middle-aged woman. PMID:24807799

  10. Methods of rapid orbit forecasting after maneuvers for geostationary satellites

    Institute of Scientific and Technical Information of China (English)

    YANG XuHai; LI ZhiGang; FENG ChuGang; GUO Ji; SHI HuLi; AI GuoXiang; WU FengLei; QIAO RongChuan

    2009-01-01

    A geostationary (GEO) satellite may serve as a navigation satellite,but there is a problem that maneuvers frequently occur and the forces are difficult to model.Based on the technique of determining setellite orbits by transfer,a predicted orbit with high accuracy may be achieved by the method of statistical orbit determination in case of no maneuver force.The predicted orbit will soon be invalid after the maneuver starts,and it takes a long time to get a valid orbit after the maneuver ends.In order to improve ephemeris usability,the method of rapid orbit forecasting after maneuvers is studied.First,GEO satellite movement is analyzed in case of maneuvers based on the observation from the orbit measurement system by transfer.Then when a GEO satellite is in the free status just after maneuvers,the short arc observation is used to forecast the orbit.It is assumed that the common system bias and biases of each station are constant,which can be obtained from orbit determination with long arc observations.In this way,only 6 orbit elements would be solved by the method of statistical orbit determination,and the ephemeris with high accuracy may be soon obtained.Actual orbit forecasting with short arc observation for SlNOSAT-1 satellite shows that,with the tracking network available,the precision of the predicted orbit (RMS of O-C) can reach about 5 m with 15 min arc observation,and about 3 m with 30 min arc observation.

  11. Methods of rapid orbit forecasting after maneuvers for geostationary satellites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A geostationary(GEO) satellite may serve as a navigation satellite,but there is a problem that maneuvers frequently occur and the forces are difficult to model.Based on the technique of determining satellite orbits by transfer,a predicted orbit with high accuracy may be achieved by the method of statis-tical orbit determination in case of no maneuver force.The predicted orbit will soon be invalid after the maneuver starts,and it takes a long time to get a valid orbit after the maneuver ends.In order to improve ephemeris usability,the method of rapid orbit forecasting after maneuvers is studied.First,GEO satellite movement is analyzed in case of maneuvers based on the observation from the orbit meas-urement system by transfer.Then when a GEO satellite is in the free status just after maneuvers,the short arc observation is used to forecast the orbit.It is assumed that the common system bias and biases of each station are constant,which can be obtained from orbit determination with long arc observations.In this way,only 6 orbit elements would be solved by the method of statistical orbit determination,and the ephemeris with high accuracy may be soon obtained.Actual orbit forecasting with short arc observation for SINOSAT-1 satellite shows that,with the tracking network available,the precision of the predicted orbit(RMS of O-C) can reach about 5 m with 15 min arc observation,and about 3 m with 30 min arc observation.

  12. Orbital Plots Using Gnuplot

    Science.gov (United States)

    Moore, Brian G.

    2000-06-01

    The plotting program Gnuplot is freely available, general purpose, easy to use, and available on a variety of platforms. Complex three-dimensional surfaces, including the familiar angular parts of the hydrogen atom orbitals, are easily represented using Gnuplot. Contour plots allow viewing the radial and angular variation of the probability density in an orbital. Examples are given of how Gnuplot is used in an undergraduate physical chemistry class to view familiar atomic orbitals in new ways or to generate views of orbital functions that the student may have not seen before. Gnuplot may also be easily integrated into the environment of a Web page; an example of this is discussed (and is available at http://onsager.bd.psu.edu/~moore/orbitals_gnuplot). The plotting commands are entered with a form and a CGI script is used to run Gnuplot and display the result back to the browser.

  13. Orbit Stabilization of Nanosat

    Energy Technology Data Exchange (ETDEWEB)

    JOHNSON,DAVID J.

    1999-12-01

    An algorithm is developed to control a pulsed {Delta}V thruster on a small satellite to allow it to fly in formation with a host satellite undergoing time dependent atmospheric drag deceleration. The algorithm uses four short thrusts per orbit to correct for differences in the average radii of the satellites due to differences in drag and one thrust to symmetrize the orbits. The radial difference between the orbits is the only input to the algorithm. The algorithm automatically stabilizes the orbits after ejection and includes provisions to allow azimuthal positional changes by modifying the drag compensation pulses. The algorithm gives radial and azimuthal deadbands of 50 cm and 3 m for a radial measurement accuracy of {+-} 5 cm and {+-} 60% period variation in the drag coefficient of the host. Approaches to further reduce the deadbands are described. The methodology of establishing a stable orbit after ejection is illustrated in an appendix. The results show the optimum ejection angle to minimize stabilization thrust is upward at 86{sup o} from the orbital velocity. At this angle the stabilization velocity that must be supplied by the thruster is half the ejection velocity. An ejection velocity of 0.02 m/sat 86{sup o} gives an azimuthal separation after ejection and orbit stabilization of 187 m. A description of liquid based gas thrusters suitable for the satellite control is included in an appendix.

  14. Quark Orbital Angular Momentum

    Directory of Open Access Journals (Sweden)

    Burkardt Matthias

    2015-01-01

    Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.

  15. Prototyping LHC Orbit Control

    CERN Document Server

    Wijnands, Thijs; Srinivasan, B

    2002-01-01

    Orbit correction consists in adjusting the strengths of the corrector magnets to make the measured beam position match a predefined reference. In the LHC, this involves around 2000 sensors and more than 1000 actuators that are distributed along both rings. The orbit correction scheme should be able to compensate for very slow orbit drifts in the range of a 10-2 Hz but also for fast motions (vibrations) up to 1 Hz. In this paper we investigate correction schemes that could be used in either case. The choice of design formalisms is based on the experience we gained with the SPS and the LEP.

  16. Dynamical mass transfer in cataclysmic binaries

    Science.gov (United States)

    Melia, Fulvio; Lamb, D. Q.

    1987-01-01

    When a binary comes into contact and mass transfer begins, orbital angular momentum is stored in the accretion disk until the disk couples tidally to the binary system. Taam and McDermott (1987) have suggested that this leads to unstable dynamical mass transfer in many cataclysmic variables in which mass transfer would otherwise be stable, and that it explains the gap between 2 and 3 h in the orbital period distribution of these systems. Here the consequences of this hypothesis for the evolution of cataclysmic binaries are explored. It is found that systems coming into contact longward of the period gap undergo one or more episodes of dynamical mass transfer.

  17. The difficulty of measuring orbital angular momentum

    Directory of Open Access Journals (Sweden)

    D. Preece

    2011-09-01

    Full Text Available Light can carry angular momentum as well as energy and momentum; the transfer of this angular momentum to an object results in an optical torque. The development of a rotational analogue to the force measurement capability of optical tweezers is hampered by the difficulty of optical measurement of orbital angular momentum. We present an experiment with encouraging results, but emphasise the difficulty of the task.

  18. Envelopes of Cometary Orbits

    Directory of Open Access Journals (Sweden)

    Mijajlović, Ž.

    2008-12-01

    Full Text Available We discuss cometary orbits from the standpoint of Nonstandard (Leibnitz analysis, a relatively new branch of mathematics. In particular, we consider parabolic cometary paths. It appears that, in a sense, every parabola is an ellipse.

  19. Orbital interactions in chemistry

    CERN Document Server

    Albright, Thomas A; Whangbo, Myung-Hwan

    2013-01-01

    Explains the underlying structure that unites all disciplines in chemistry Now in its second edition, this book explores organic, organometallic, inorganic, solid state, and materials chemistry, demonstrating how common molecular orbital situations arise throughout the whole chemical spectrum. The authors explore the relationships that enable readers to grasp the theory that underlies and connects traditional fields of study within chemistry, thereby providing a conceptual framework with which to think about chemical structure and reactivity problems. Orbital Interactions

  20. Dexter energy transfer pathways.

    Science.gov (United States)

    Skourtis, Spiros S; Liu, Chaoren; Antoniou, Panayiotis; Virshup, Aaron M; Beratan, David N

    2016-07-19

    Energy transfer with an associated spin change of the donor and acceptor, Dexter energy transfer, is critically important in solar energy harvesting assemblies, damage protection schemes of photobiology, and organometallic opto-electronic materials. Dexter transfer between chemically linked donors and acceptors is bridge mediated, presenting an enticing analogy with bridge-mediated electron and hole transfer. However, Dexter coupling pathways must convey both an electron and a hole from donor to acceptor, and this adds considerable richness to the mediation process. We dissect the bridge-mediated Dexter coupling mechanisms and formulate a theory for triplet energy transfer coupling pathways. Virtual donor-acceptor charge-transfer exciton intermediates dominate at shorter distances or higher tunneling energy gaps, whereas virtual intermediates with an electron and a hole both on the bridge (virtual bridge excitons) dominate for longer distances or lower energy gaps. The effects of virtual bridge excitons were neglected in earlier treatments. The two-particle pathway framework developed here shows how Dexter energy-transfer rates depend on donor, bridge, and acceptor energetics, as well as on orbital symmetry and quantum interference among pathways.

  1. 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.

  2. [Orbital complications of sinusitis].

    Science.gov (United States)

    Šuchaň, M; Horňák, M; Kaliarik, L; Krempaská, S; Koštialová, T; Kovaľ, J

    2014-12-01

    Orbital complications categorised by Chandler are emergency. They need early diagnosis and agresive treatment. Stage and origin of orbital complications are identified by rhinoendoscopy, ophtalmologic examination and CT of orbite and paranasal sinuses. Periorbital cellulitis and early stage of orbital cellulitis can be treated conservatively with i. v. antibiotics. Monitoring of laboratory parameters and ophtalmologic symptoms is mandatory. Lack of improvement or worsening of symptoms within 24-48 hours and advanced stages of orbital complications are indicated for surgery. The purpose of the study is to evaluate epidemiology, clinical features and management of sinogenic orbital complications. Retrospective data of 8 patients with suspicion of orbital complication admited to hospital from 2008 to 2013 were evaluated. Patients were analyzed in terms of gender, age, CT findings, microbiology, clinical features, stage and treatment. Male and female were afected in rate 1,66:1. Most of patients were young adult in 3rd. and 4th. decade of life (62,5 %). Acute and chronic sinusitis were cause of orbital complication in the same rate. The most common origin of orbital complication was ethmoiditis (62,5 %), than maxillary (25 %) and frontal (12,5 %) sinusitis. Polysinusitis with affection of ethmoidal, maxillary and frontal sinuses (75 %) was usual CT finding. Staphylococcus epidermidis and Staphylococcus aureus were etiological agens in half of cases. Periorbital oedema (100 %), proptosis, chemosis (50 %), diplopia and glaucoma (12,5 %) were observed. Based on examinations, diagnosis of periorbital oedema/preseptal cellulitis was made in 3 (37,5 %), orbital cellulitis in 3 (37,5 %) and subperiosteal abscess in 2 cases (25 %). All patients underwent combined therapy - i. v. antibiotics and surgery within 24 hours. Eradication of disease from ostiomeatal complex (OMC), drainage of affected sinuses and drainage of subperiosteal abscess were done via fuctional endonasal

  3. Orbit Propagation and Determination of Low Earth Orbit Satellites

    OpenAIRE

    Ho-Nien Shou

    2014-01-01

    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 t...

  4. Orbits for sixteen binaries

    Directory of Open Access Journals (Sweden)

    Cvetković Z.

    2006-01-01

    Full Text Available In this paper orbits for 13 binaries are recalculated and presented. The reason is that recent observations show higher residuals than the corresponding ephemerides calculated by using the orbital elements given in the Sixth Catalog of Orbits of Visual Binary Stars. The binaries studied were: WDS 00182+7257 = A 803, WDS 00335+4006 = HO 3, WDS 00583+2124 = BU 302, WDS 01011+6022 = A 926, WDS 01014+1155 = BU 867, WDS 01112+4113 = A 655, WDS 01361−2954 + HJ 3447, WDS 02333+5219 = STT 42 AB,WDS 04362+0814 = A 1840 AB,WDS 08017−0836 = A 1580, WDS 08277−0425 = A 550, WDS 17471+1742 = STF 2215 and WDS 18025+4414 = BU 1127 Aa-B. In addition, for three binaries - WDS 01532+1526 = BU 260, WDS 02563+7253 = STF 312 AB and WDS 05003+3924 = STT 92 AB - the orbital elements are calculated for the first time. In this paper the authors present not only the orbital elements, but the masses dynamical parallaxes, absolute magnitudes and ephemerides for the next five years, as well.

  5. Helioseismology with Solar Orbiter

    CERN Document Server

    Löptien, Björn; Gizon, Laurent; Schou, Jesper; Appourchaux, Thierry; Rodríguez, Julián Blanco; Cally, Paul S; Dominguez-Tagle, Carlos; Gandorfer, Achim; Hill, Frank; Hirzberger, Johann; Scherrer, Philip H; Solanki, Sami K

    2014-01-01

    The Solar Orbiter mission, to be launched in July 2017, will carry a suite of remote sensing and in-situ instruments, including the Polarimetric and Helioseismic Imager (PHI). PHI will deliver high-cadence images of the Sun in intensity and Doppler velocity suitable for carrying out novel helioseismic studies. The orbit of the Solar Orbiter spacecraft will reach a solar latitude of up to 21 deg (up to 34 deg by the end of the extended mission) and thus will enable the first local helioseismology studies of the polar regions. Here we consider an array of science objectives to be addressed by helioseismology within the baseline telemetry allocation (51 Gbit per orbit, current baseline) and within the science observing windows (baseline 3 x 10 days per orbit). A particularly important objective is the measurement of large-scale flows at high latitudes (rotation and meridional flow), which are largely unknown but play an important role in flux transport dynamos. The full range of Earth-Sun-spacecraft angles provi...

  6. Extended duration orbiter (EDO) insignia

    Science.gov (United States)

    1990-01-01

    Extended duration orbiter (EDO) insignia incorporates a space shuttle orbiter with payload bay doors (PLBDs) open and a spacelab module inside. Trailing the orbiter are the initials EDO. The EDO-modified Columbia, Orbiter Vehicle (OV) 102, will be flown for the first EDO mission, STS-50.

  7. Interacting Binaries with Eccentric Orbits. III. Orbital Evolution due to Direct Impact and Self-Accretion

    CERN Document Server

    Sepinsky, J F; Kalogera, V; Rasio, F A

    2010-01-01

    The rapid circularization and synchronization of the stellar components in an eccentric binary system at the onset of mass transfer is a fundamental assumption common to all binary stellar evolution and population synthesis codes, even though the validity of this assumption is questionable both theoretically and observationally. Here we calculate the evolution of the orbital elements of an eccentric binary through the direct three-body integration of a massive particle ejected through the inner Lagrangian point of the donor star at periastron. The trajectory of this particle leads to three possible outcomes: direct accretion onto the companion star within a single orbit, self-accretion back onto the donor star within a single orbit, or a quasi-periodic orbit around the companion star, possibly leading to the formation of a disk. We calculate the secular evolution of the binary orbit in the first two cases and conclude that direct impact accretion can increase as well as decrease the orbital semi-major axis an...

  8. Numerical simulation of orbitally shaken viscous fluids with free surface

    OpenAIRE

    Discacciati, Marco; Hacker, David; Quarteroni, A.; Quinodoz, Samuel; Tissot, Stéphanie; Wurm, M. Florian

    2013-01-01

    Orbitally shaken bioreactors are an emerging alternative to stirred-tank bioreactors for large-scale mam- malian cell culture, but their fluid dynamics is still not well defined. Among the theoretical and practical issues that remain to be resolved, the characterization of the liquid free surface during orbital shaking remains a major challenge because it is an essential aspect of gas transfer and mixing in these reactors. To simulate the fluid behavior and the free surface shape, we develope...

  9. 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.

  10. Vertical orbital dystopia.

    Science.gov (United States)

    Tan, S T; Ashworth, G; Czypionka, S; Poole, M D; Briggs, M

    1996-06-01

    Many pathologic processes may lead to vertical orbital dystopia. We reviewed 47 consecutive cases seen over a 13-year period. Twenty-nine patients underwent eye leveling procedures to improve cosmesis, 2 of these by camouflage procedures and 27 by orbital translocation. Ten patients had 16 secondary operations. There was one death, serious complications occurred in 3 patients, and nuisance complications occurred in 20 others. Seven patients developed diplopia postoperatively, and in 6 patients it was troublesome. In these, it resolved fully in 2 patients, improved to be of no consequence in 2, and in the remaining 2 troublesome symptoms persisted requiring inferior oblique muscle recession in 1. Binocular vision was never restored when not present preoperatively, and in 3 patients temporary loss occurred. There was an overall modest but significant improvement in appearance after surgery. It is concluded that vertical orbital translocation is rewarding and worthwhile.

  11. Deceleration Orbit Improvements

    Energy Technology Data Exchange (ETDEWEB)

    Church, M.

    1991-04-26

    During the accelerator studies period of 12/90-1/91 much study time was dedicated to improving the E760 deceleration ramps. 4 general goals were in mind: (1) Reduce the relative orbit deviations from the nominal reference orbit as much as possible. This reduces the potential error in the orbit length calculation - which is the primary source of error in the beam energy calculation. (2) Maximize the transverse apertures. This minimizes beam loss during deceleration and during accidental beam blow-ups. (3) Measure and correct lattice parameters. Knowledge of {gamma}{sub T}, {eta}, Q{sub h}, Q{sub v}, and the dispersion in the straight sections allows for a more accurate energy calculation and reliable SYNCH calculations. (4) Minimize the coupling. This allows one to discern between horizontal and vertical tunes.

  12. [Secondary orbital lymphoma].

    Science.gov (United States)

    Basanta, I; Sevillano, C; Álvarez, M D

    2015-09-01

    A case is presented of an 85 year-old Caucasian female with lymphoma that recurred in the orbit (secondary ocular adnexal lymphoma). The orbital tumour was a diffuse large B-cell lymphoma according to the REAL classification (Revised European-American Lymphoma Classification). Orbital lymphomas are predominantly B-cell proliferations of a variety of histological types, and most are low-grade tumours. Patients are usually middle-aged or elderly, and it is slightly more common in women. A palpable mass, proptosis and blepharoptosis are the most common signs of presentation. Copyright © 2011 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  13. New Measurements of Orbital Period Change in Cygnus X-3

    CERN Document Server

    Singh, N S; Paul, B; Agrawal, P C; Rao, A R; Singh, K Y

    2002-01-01

    A nonlinear nature of the binary ephemeris of Cygnus X-3 indicates either a change in the orbital period or an apsidal motion of the orbit. We have made extended observations of Cygnus X-3 with the Pointed Proportional Counters (PPCs) of the Indian X-ray Astronomy Experiment (IXAE) during 1999 July 3-13 and October 11-14. Using the data from these observations and the archival data from ROSAT, ASCA, BeppoSAX and RXTE, we have extended the data base for this source. Adding these new arrival time measurements to the published results, we make a comparison between the various possibilities, (a) orbital decay due to mass loss from the system, (b) mass transfer between the stars, and (c) apsidal motion of the orbit due to gravitational interaction between the two components. Orbital decay due to mass loss from the companion star seems to be the most probable scenario.

  14. Optical orbital angular momentum

    Science.gov (United States)

    Barnett, Stephen M.; Babiker, Mohamed; Padgett, Miles J.

    2017-01-01

    We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069775

  15. Optical orbital angular momentum

    Science.gov (United States)

    Barnett, Stephen M.; Babiker, Mohamed; Padgett, Miles J.

    2017-02-01

    We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next. This article is part of the themed issue 'Optical orbital angular momentum'.

  16. Lyapunov Orbits in the Jupiter System Using Electrodynamic Tethers

    Science.gov (United States)

    Bokelmann, Kevin; Russell, Ryan P.; Lantoine, Gregory

    2013-01-01

    Various researchers have proposed the use of electrodynamic tethers for power generation and capture from interplanetary transfers. The effect of tether forces on periodic orbits in Jupiter-satellite systems are investigated. A perturbation force is added to the restricted three-body problem model and a series of simplifications allows development of a conservative system that retains the Jacobi integral. Expressions are developed to find modified locations of equilibrium positions. Modified families of Lyapunov orbits are generated as functions of tether size and Jacobi integral. Zero velocity curves and stability analyses are used to evaluate the dynamical properties of tether-modified orbits.

  17. Lyapunov Orbits in the Jupiter System Using Electrodynamic Tethers

    Science.gov (United States)

    Bokelmann, Kevin; Russell, Ryan P.; Lantoine, Gregory

    2013-01-01

    Various researchers have proposed the use of electrodynamic tethers for power generation and capture from interplanetary transfers. The effect of tether forces on periodic orbits in Jupiter-satellite systems are investigated. A perturbation force is added to the restricted three-body problem model and a series of simplifications allows development of a conservative system that retains the Jacobi integral. Expressions are developed to find modified locations of equilibrium positions. Modified families of Lyapunov orbits are generated as functions of tether size and Jacobi integral. Zero velocity curves and stability analyses are used to evaluate the dynamical properties of tether-modified orbits.

  18. Design requirements for orbit maintenance of SPS elements

    Energy Technology Data Exchange (ETDEWEB)

    1980-11-01

    The objective of this study is to identify the design and operational requirements that will be imposed by the need to avoid unplanned reentry of SPS elements. The LEO Staging Base, Electric Orbit Transfer Vehicle, the LEO Construction Base, and SPS Self-Power Module are the SPS elements selected for this analysis. The orbit decay rates and attitude control/orbit maintenance propellant requirements for nominal and worst case conditions are defined. The sequence of events that could cause unplanned reentry are defined. The design and operational requirements that will be used to prevent the various elements from deorbiting are defined.

  19. Radionuclide transfer. Radionuklid Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, G.B.

    1993-01-01

    The research project described here had the aim to obtain further information on the transfer of nuclides during pregnancy and lactation. The tests were carried out in mini-pigs and rats receiving unchanging doses of radionuclides with the food. The following findings were revealed for the elements examined: Fe, Se, Cs and Zn were characterized by very high transfer levels in the mother, infant and foetus. A substantial uptake by the mother alone was observed for Co, Ag and Mn. The uptake by the foetus and infant here was 1 to 10 times lower. A preferential concentration in certain tissues was seen for Sr and Tc; the thyroid levels of Tc were about equally high in mothers and infants, while Sr showed less accumulation in the maternal bone. The lanthanide group of substances (Ce, Eu and Gd as well as Y and Ru) were only taken up to a very limited extent. The uptake of the examined radionuclides (Fe, Co, Ag, Ce) with the food ingested was found here to be ten times greater in rats as compared to mini-pigs. This showed that great caution must be observed, if the behaviour of radionuclides in man is extrapolated from relevant data obtained in rodents. (orig./MG)

  20. Local orbitals by minimizing powers of the orbital variance

    DEFF Research Database (Denmark)

    Jansik, Branislav; Høst, Stinne; Kristensen, Kasper;

    2011-01-01

    It is demonstrated that a set of local orthonormal Hartree–Fock (HF) molecular orbitals can be obtained for both the occupied and virtual orbital spaces by minimizing powers of the orbital variance using the trust-region algorithm. For a power exponent equal to one, the Boys localization function...... is obtained. For increasing power exponents, the penalty for delocalized orbitals is increased and smaller maximum orbital spreads are encountered. Calculations on superbenzene, C60, and a fragment of the titin protein show that for a power exponent equal to one, delocalized outlier orbitals may...

  1. Solar Orbiter Status Report

    Science.gov (United States)

    Gilbert, Holly; St. Cyr, Orville Chris; Mueller, Daniel; Zouganelis, Yannis; Velli, Marco

    2017-08-01

    With the delivery of the instruments to the spacecraft builder, the Solar Orbiter mission is in the midst of Integration & Testing phase at Airbus in Stevenage, U.K. This mission to “Explore the Sun-Heliosphere Connection” is the first medium-class mission of ESA’s Cosmic Vision 2015-2025 program and is being jointly implemented with NASA. The dedicated payload of 10 remote-sensing and in-situ instruments will orbit the Sun as close as 0.3 A.U. and will provide measurments from the photosphere into the solar wind. The three-axis stabilized spacecraft will use Venus gravity assists to increase the orbital inclination out of the ecliptic to solar latitudes as high as 34 degrees in the extended mission. The science team of Solar Orbiter has been working closely with the Solar Probe Plus scientists to coordinate observations between these two highly-complementary missions. This will be a status report on the mission development; the interested reader is referred to the recent summary by Müller et al., Solar Physics 285 (2013).

  2. Sedna Orbit Animation

    Science.gov (United States)

    2004-01-01

    This animation shows the location of the newly discovered planet-like object, dubbed 'Sedna,' in relation to the rest of the solar system. Starting at the inner solar system, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green). Pluto and the distant Kuiper Belt objects are seen next until finally Sedna comes into view. As the field widens the full orbit of Sedna can be seen along with its current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. Moving past Sedna, what was previously thought to be the inner edge of the Oort cloud appears. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

  3. Myxoma of the orbit.

    Directory of Open Access Journals (Sweden)

    Rambhatla Saptagirish

    2003-01-01

    Full Text Available Myxomas are rare, benign neoplasms of mesenchymal origin that usually develop in soft tissues. As the clinical manifestations are non-specific, it is difficult to diagnose the tumour without biopsy and histopathological examination. We report a case of orbital myxoma with histopathological correlation.

  4. Sedna Orbit Animation

    Science.gov (United States)

    2004-01-01

    This animation shows the location of the newly discovered planet-like object, dubbed 'Sedna,' in relation to the rest of the solar system. Starting at the inner solar system, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green). Pluto and the distant Kuiper Belt objects are seen next until finally Sedna comes into view. As the field widens the full orbit of Sedna can be seen along with its current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. Moving past Sedna, what was previously thought to be the inner edge of the Oort cloud appears. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

  5. Trajectory Design and Orbital Dynamics of Deep Space Exploration

    Science.gov (United States)

    Zhao, Y. H.

    2013-05-01

    The term of deep space exploration is used for the exploration in which a probe, unlike an earth satellite, escapes from the Earth's gravitation field, and conducts the exploration of celestial bodies within or away from the solar system. As the progress of aerospace science and technology, the exploration of the Moon and other planets of the solar system has attracted more and more attention throughout the world since late 1990s. China also accelerated its progress of the lunar exploration in recent years. Its first lunar-orbiting spacecraft, Chang'e 1, was successfully launched on 2007 October 24. It then achieved the goals of accurate maneuver and lunar orbiting, acquired a large amount of scientific data and a full lunar image, and finally impacted the Moon under control. On 2010 October 1, China launched Chang'e 2 with success, which obtained a full lunar image with a higher resolution and a high-definition image of the Sinus Iridum, and completed multiple extended missions such as orbiting the Lagrangian point L2, laying the groundwork for future deep space exploration. As the first phase of the three main operational phases (orbiting, landing, return) of the Chinese Lunar Exploration Program, the successful launches and flights of Chang'e 1 and Chang'e 2 are excellent applications of the orbit design of both the Earth-Moon transfer orbit and the circumlunar orbit, yet not involving the design of the entire trajectory consisting of the Earth-Moon transfer orbit, the circumlunar orbit, and the return orbit, which is produced particularly for sample return spacecraft. This paper studies the entire orbit design of the lunar sample return spacecraft which would be employed in both the third phase of the lunar exploration program and the human lunar landing program, analyzes the dynamic characteristics of the orbit, and works out the launch windows based on specific conditions. The results are universally applicable, and could serve as the basis of the orbit

  6. Integrated MLI: Advanced Thermal Insulation for Propellant Storage and Transfer Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cryogenic propellants, orbital cryogenic fuel depots and the ability to store, transfer, handle and refuel spacecraft in orbit are critical to NASA future missions...

  7. Unusual Sclerosing Orbital Pseudotumor Infiltrating Orbits and Maxillofacial Regions

    Directory of Open Access Journals (Sweden)

    Huseyin Toprak

    2014-01-01

    Full Text Available Idiopathic orbital pseudotumor (IOP is a benign inflammatory condition of the orbit without identifiable local or systemic causes. Bilateral massive orbital involvement and extraorbital extension of the IOP is very rare. We present an unusual case of IOP with bilateral massive orbital infiltration extending into maxillofacial regions and discuss its distinctive magnetic resonance imaging (MRI features that help to exclude other entities during differential diagnoses.

  8. Orbit correction algorithm for SSRF fast orbit feedback system

    Institute of Scientific and Technical Information of China (English)

    LIU Ming; YIN Chongxian; LIU Dekang

    2009-01-01

    A fast orbit feedback system is designed at SSRF to suppress beam orbit disturbance within sub-micron in the bandwidth up to 100 Hz.The SVD (Singular value decomposition) algorithm is applied to calculate the inverse response matrix in global orbit correction.The number of singular eigenvalues will influence orbit noise suppression and corrector strengths.The method to choose singular eigenvalue rejection threshold is studied in this paper,and the simulation and experiment results are also presented.

  9. Comparison of Low Earth Orbit and Geosynchronous Earth Orbits

    Science.gov (United States)

    Drummond, J. E.

    1980-01-01

    The technological, environmental, social, and political ramifications of low Earth orbits as compared to geosynchronous Earth orbits for the solar power satellite (SPS) are assessed. The capital cost of the transmitting facilities is dependent on the areas of the antenna and rectenna relative to the requirement of high efficiency power transmission. The salient features of a low orbit Earth orbits are discussed in terms of cost reduction efforts.

  10. Transfer Pricing

    DEFF Research Database (Denmark)

    Nielsen, Søren Bo

    2014-01-01

    Against a background of rather mixed evidence about transfer pricing practices in multinational enterprises (MNEs) and varying attitudes on the part of tax authorities, this paper explores how multiple aims in transfer pricing can be pursued across four different transfer pricing regimes. A MNE h...

  11. Pragmatic Transfer.

    Science.gov (United States)

    Kasper, Gabriele

    1992-01-01

    Attempting to clarify the concept of pragmatic transfer, this article proposes as a basic distinction Leech/Thomas' dichotomy of sociopragmatics versus pragmalinguistics, presenting evidence for transfer at both levels. Issues discussed include pragmatic universals in speech act realization, conditions for pragmatic transfer, communicative…

  12. Diplopia secondary to orbital surgery.

    Science.gov (United States)

    Silbert, David I; Matta, Noelle S; Singman, Eric L

    2012-01-01

    Diplopia may occur following any type of ocular or pericocular surgery. The surgeries most frequently associated with postoperative diplopia include: repair of orbital fracture, endoscopic sinus surgery (from inadvertent orbital penetration), and orbital decompression for thyroid-related immune orbitopathy (TRIO). Postoperative diplopia after orbital tumor resection has been reported--e.g., after excision of fibrous dysplasia and osteoma. However, a recent case series suggests diplopia after orbital tumor resection is uncommon and transient. Surgical intervention for orbital trauma carries the highest risk of postoperative diplopia and will be the focus of this review. We will also present a case report of worsening diplopia following repair of orbital floor fracture to highlight potential motility issues that can arise when implants are employed to treat orbital floor fractures.

  13. Topics in orbit equivalence

    CERN Document Server

    Kechris, Alexander S

    2004-01-01

    This volume provides a self-contained introduction to some topics in orbit equivalence theory, a branch of ergodic theory. The first two chapters focus on hyperfiniteness and amenability. Included here are proofs of Dye's theorem that probability measure-preserving, ergodic actions of the integers are orbit equivalent and of the theorem of Connes-Feldman-Weiss identifying amenability and hyperfiniteness for non-singular equivalence relations. The presentation here is often influenced by descriptive set theory, and Borel and generic analogs of various results are discussed. The final chapter is a detailed account of Gaboriau's recent results on the theory of costs for equivalence relations and groups and its applications to proving rigidity theorems for actions of free groups.

  14. Small Mercury Relativity Orbiter

    Science.gov (United States)

    Bender, Peter L.; Vincent, Mark A.

    1989-01-01

    The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

  15. Preseptal and orbital cellulitis

    Directory of Open Access Journals (Sweden)

    Emine Akçay

    2014-09-01

    Full Text Available Preseptal cellulitis (PC is defined as an inflammation of the eyelid and surrounding skin, whereas orbital cellulitis (OC is an inflammation of the posterior septum of the eyelid affecting the orbit and its contents. Periorbital tissues may become infected as a result of trauma (including insect bites or primary bacteremia. Orbital cellulitis generally occurs as a complication of sinusitis. The most commonly isolated organisms are Staphylococcus aureus, Streptococcus pneumoniae, S. epidermidis, Haempphilus influenzae, Moraxella catarrhalis and S. pyogenes. The method for the diagnosis of OS and PS is computed tomography. Using effective antibiotics is a mainstay for the treatment of PC and OC. There is an agreement that surgical drainage should be performed in cases of complete ophthalmoplegia or significant visual impairment or large abscesses formation. This infections are also at a greater risk of acute visual loss, cavernous sinus thrombosis, meningitis, cerebritis, endophthalmitis, and brain abscess in children. Early diagnosis and appropriate treatment are crucial to control the infection. Diagnosis, treatment, management and complications of PC and OC are summarized in this manuscript. J MicrobiolInfect Dis 2014; 4(3: 123-127

  16. Flight Performance Handbook for Orbital Operations: Orbital Mechanics and Astrodynamics Formulae, Theorems, Techniques, and Applications

    Science.gov (United States)

    Ambrosio, Alphonso; Blitzer, Leon; Conte, S.D.; Cooper, Donald H.; Dergarabedian, P.; Dethlefsen, D.G.; Lunn, Richard L.; Ireland, Richard O.; Jensen, Arnold A.; Kang, Garfield; Levy, Ezra C.; Liu, Anthony; Marcus, Silvia R.; Mickelwait, A.B.; Moe, Kenneth; Moe, Mildred M.; Pitton, A.R.; Scheuer, Ernest M.; Tompkins, E.H.; Weiser, Peter B.; Whitford, R.K.; Wolverton, R.W.

    1961-01-01

    This handbook provides parametric data useful both to the space vehicle designer and mission analyst. It provides numerical and analytical relationships between missions and gross vehicle characteristics as a function of performance parameters. The effects of missile constraints and gross guidance limitations plus operational constraints such as launch site location, tracking net location, orbit visibility and mission on trajectory and orbit design parameters are exhibited. The influence of state-of- the-art applications of solar power as compared to future applications of nuclear power on orbit design parameters, such as eclipse time, are among the parameters included in the study. The principal aim, however, is in providing the analyst with useful parametric design information to cover the general area of earth satellite missions in the region of near-earth to cislunar space and beyond and from injection to atmospheric entry and controlled descent. The chapters are organized around the central idea of orbital operations in the 1961-1969 era with emphasis on parametric flight mechanics studies for ascent phase and parking orbits, transfer maneuvers, rendezvous maneuver, operational orbit considerations, and operational orbit control. The results are based almost entirely on the principles of flight and celestial mechanics. Numerous practical examples have been worked out in detail. This is especially important where it has been difficult or impossible to represent all possible variations of the parameters. The handbook contains analytical formulae and sufficient textual material to permit their proper use. The analytic methods consist of both exact and rapid, approximate methods. Scores of tables, working graphs and illustrations amplify the mathematical models which, together with important facts and data, cover the engineering and scientific applications of orbital mechanics. Each of the five major chapters are arranged to provide a rapid review of an entire

  17. Chaos Behaviour of Molecular Orbit

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Tang; SUN Fu-Yan; SHEN Shu-Lan

    2007-01-01

    Based on H(u)ckel's molecular orbit theory,the chaos and;bifurcation behaviour of a molecular orbit modelled by a nonlinear dynamic system is studied.The relationship between molecular orbit and its energy level in the nonlinear dynamic system is obtained.

  18. Spin Orbit Torque in Ferromagnetic Semiconductors

    KAUST Repository

    Li, Hang

    2016-06-21

    Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read\\' and `write\\' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall

  19. The EJSM Jupiter-Ganymede Orbiter

    Science.gov (United States)

    Blanc, M.; Lebreton, J.-P.; Stankov, A.; Greeley, R.; Pappalardo, R. T.; Fujimoto, M.

    2008-09-01

    The Europa-Jupiter System Mission (EJSM), currently subject of a joint study by NASA, ESA and JAXA, would combine a fleet of three satellites in order to investigate in depth many questions related to the Jupiter System. These investigations are essential for our understanding of the emergence and evolution of habitable worlds, not only within the Solar System, but also for extrasolar planet investigations. Scientific targets of EJSM focus on Europa and Ganymede as a key pair of Galilean satellites, to address the questions on their habitability, formation, and internal structure, as well as the coupling with the whole Jovian system: Jupiter's atmosphere and interior, magnetosphere and magnetodisk.. In combination with a Jupiter Europa Orbiter (JEO that would be provided by NASA) and a Jupiter Magnetospheric Orbiter (JMO that would be provided by JAXA), ESA is studying a Jupiter Ganymede Orbiter (JGO). The mission scenario includes a launch in 2020 with a transfer time to Jupiter of ~6 years. After the orbit insertion around Jupiter, a first phase (~2 years) will be devoted to Jupiter system and Callisto studies, with multiple flybys of Callisto planned at low altitude (~200 km), followed by a Ganymede orbit insertion and extensive study of Ganymede (~1 year). In depth comparative study of inner (Io and Europe) and outer (Ganymede and Callisto) satellites with combined payload of JEO and JGO will address the question of the geologic relative evolution of the satellites. On JGO, the transport phenomena in the magnetosphere of Jupiter will be studied in combination with JMO, and the Ganymede magnetosphere will be observed in situ. Jupiter atmosphere investigations on JGO will focus on coupling phenomena between troposphere, stratosphere and mesosphere, the stratospheric composition and the question of thermospheric heating.

  20. Multi-Body Capture to Low-altitude Circular Orbits at Europa

    Science.gov (United States)

    Grebow, Daniel J.; Petropoulos, Anastassios E.; Finlayson, Paul A.

    2011-01-01

    For capture to a 200-km circular orbit around Europa, millions of different points along the orbit are simulated in the Jupiter-Europa Restricted 3-Body Problem. The transfers exist as members of families of trajectories, where certain families consistently outperform the others. The trajectories are not sensitive to changes in inclination for the final circular orbit. The top performing trajectories appear to follow the invariant manifolds of L2 Lyapunov orbits for capture into a retrograde orbit, and in some cases saving up to 40% of the from the patched 2-body problem. Transfers are attached to the current nominal mission for NASA's Jupiter-Europa Orbiter, where the total cost is roughly 100 m/s less than the baseline mission.

  1. Orbital Optimization in the Active Space Decomposition Model

    CERN Document Server

    Kim, Inkoo; Shiozaki, Toru

    2015-01-01

    We report the derivation and implementation of orbital optimization algorithms for the active space decomposition (ASD) model, which are extensions of complete active space self-consistent field (CASSCF) and its occupation-restricted variants in the conventional multiconfiguration electronic-structure theory. Orbital rotations between active subspaces are included in the optimization, which allows us to unambiguously partition the active space into subspaces, enabling application of ASD to electron and exciton dynamics in covalently linked chromophores. One- and two-particle reduced density matrices, which are required for evaluation of orbital gradient and approximate Hessian elements, are computed from the intermediate tensors in the ASD energy evaluation. Numerical results on 4-(2-naphthylmethyl)-benzaldehyde and [3$_6$]cyclophane and model Hamiltonian analyses of triplet energy transfer processes in the Closs systems are presented. Furthermore model Hamiltonians for hole and electron transfer processes in...

  2. Binary evolution using the theory of osculating orbits: conservative Algol evolution

    CERN Document Server

    Davis, P J; Deschamps, R

    2014-01-01

    Our aim is to calculate the evolution of Algol binaries within the framework of the osculating orbital theory, which considers the perturbing forces acting on the orbit of each star arising from mass exchange via Roche lobe overflow (RLOF). The scheme is compared to results calculated from a `classical' prescription. Using our stellar binary evolution code BINSTAR, we calculate the orbital evolution of Algol binaries undergoing case A and case B mass transfer, by applying the osculating scheme. The velocities of the ejected and accreted material are evaluated by solving the restricted three-body equations of motion, within the ballistic approximation. This allows us to determine the change of linear momentum of each star, and the gravitational force applied by the mass transfer stream. Torques applied on the stellar spins by tides and mass transfer are also considered. Using the osculating formalism gives shorter post-mass transfer orbital periods typically by a factor of 4 compared to the classical scheme, o...

  3. Earth Orbit Raise Design for the Artemis Mission

    Science.gov (United States)

    Wiffen, Gregory J.; Sweetser, Theodore H.

    2011-01-01

    The Artemis mission is an extension of the Themis mission. The Themis mission1 consisted of five identical spacecraft in varying sized Earth orbits designed to make simultaneous measurements of the Earth's electric and magnetic environment. Themis was designed to observe geomagnetic storms resulting from solar wind's interaction with the Earth's magnetosphere. Themis was meant to answer the age old question of why the Earth's aurora can change rapidly on a global scale. The Themis spacecraft are spin stabilized with 20 meter long electric field booms as well as several shorter magnetometer booms. The goal of the Artemis2 mission extension is to deliver the field and particle measuring capabilities of two of the Themis spacecraft to the vicinity of the Moon. The Artemis mission required transferring two Earth orbiting Themis spacecraft on to two different low energy trans-lunar trajectories ultimately ending in lunar orbit. This paper describes the processes that resulted in successful orbit raise designs for both spacecraft.

  4. Libration Point Orbit Utilization for Tactical Advantage in Communications, Surveillance, and Risk Mitigation

    Science.gov (United States)

    2014-10-27

    2013 Received Paper 4.00 Kathryn Davis, George Born, Eric Butcher. Transfers to Earth–Moon L3 halo orbits, Acta Astronautica , (07 2013): 116. doi...Orbits,”Acta Astronautica , doi: 10.1016/j.actaastro.2013.03.004 (2013). [12] Lee, D. Butcher, E. A., and Sanyal, A. K., “Optimal Interior Earth

  5. 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.

  6. Galactic Habitable Orbits

    Science.gov (United States)

    Rahimi, A.; Mao, S.; Kawata, D.

    2014-03-01

    The fossil record shows that the Earth has experienced several mass extinctions over the past 500 million years1, and it has been suggested that there is a periodicity in extinction events on timescales of tens1 and/or hundreds of millions of years. Various hypotheses have been proposed to explain the cause of the mass extinctions, including the suggestion that the Earth's ozone layer may have been destroyed by intense radiation from a nearby supernovae2- 3, exposing the Earth's surface to damaging UV radiation. Recent observations of cores taken from the ocean floor revealed atoms of a very rare isotope of iron (60Fe) believed to have arrived on Earth around 2 million years ago as fallout from a nearby supernovae4. Astronomical evidence for that past supernovae was recently found in the debris of a young cluster of massive stars5, by tracing its past orbit, putting it at the right place at the right time to explain the mild extinction event. Here we report new high-resolution (both in space and time) N-body chemodynamical simulations (carried out with our novel code GCD+6) of the evolution of a model Milky Way Galaxy, tracing the orbit of èsun-like' stars over a 500 million year period, checking the proximity to supernovae throughout the history of the orbit and comparing the times when this occurs with past mass extinctions on Earth. We additionally explain the important effects of the spiral arm pattern, radial migration of stars and Galactic chemistry on habitability.

  7. Review of orbital imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goh, P.S. [Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore)], E-mail: dnrgohps@nus.edu.sg; Gi, M.T. [Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore); Charlton, A. [Department of Pathology, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore); Tan, C.; Gangadhara Sundar, J.K.; Amrith, S. [Department of Ophthalmology, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore)

    2008-06-15

    CT and MRI are commonly used in the evaluation of patients with suspected orbital disease. Many different diseases may present within this small anatomical space. The purpose of this article is to present a diagnostic strategy based on a compartment model. Localizing pathology to sinus, bone, extraconal space, muscle cone, intraconal space, optic nerve, globe or lacrimal fossa allows significant reduction in the number of differential diagnoses as these compartments contain different tissues which disease may involve or arise from. Certain diseases may also present in multiple compartments. Common diseases which might present in one or multiple compartments will be discussed.

  8. Lunar Exploration Orbiter (LEO)

    Science.gov (United States)

    Jaumann, R.; Spohn, T.; Hiesinger, H.; Jessberger, E. K.; Neukum, G.; Oberst, J.; Helbert, J.; Christensen, U.; Keller, H. U.; Mall, U.; Böhnhardt, H.; Hartogh, P.; Glassmeier, K.-H.; Auster, H.-U.; Moreira, A.; Werner, M.; Pätzold, M.; Palme, H.; Wimmer-Schweingruber, R.; Mandea, M.; Lesur, V.; Häusler, B.; Hördt, A.; Eichentopf, K.; Hauber, E.; Hoffmann, H.; Köhler, U.; Kührt, E.; Michaelis, H.; Pauer, M.; Sohl, F.; Denk, T.; van Gasselt, S.

    2007-08-01

    The Moon is an integral part of the Earth-Moon system, it is a witness to more than 4.5 b. y. of solar system history, and it is the only planetary body except Earth for which we have samples from known locations. The Moon is our closest companion and can easily be reached from Earth at any time, even with a relatively modest financial budget. Consequently, the Moon was the first logical step in the exploration of our solar system before we pursued more distant targets such as Mars and beyond. The vast amount of knowledge gained from the Apollo and other lunar missions of the late 1960's and early 1970's demonstrates how valuable the Moon is for the understanding of our planetary system. Even today, the Moon remains an extremely interesting target scientifically and technologically, as ever since, new data have helped to address some of our questions about the Earth-Moon system, many questions remained. Therefore, returning to the Moon is the critical stepping-stone to further exploring our immediate planetary neighborhood. In this concept study, we present scientific and technological arguments for a national German lunar mission, the Lunar Explorations Orbiter (LEO). Numerous space-faring nations have realized and identified the unique opportunities related to lunar exploration and have planned missions to the Moon within the next few years. Among these missions, LEO will be unique, because it will globally explore the Moon in unprecedented spatial and spectral resolution. LEO will significantly improve our understanding of the lunar surface composition, surface ages, mineralogy, physical properties, interior, thermal history, gravity field, regolith structure, and magnetic field. The Lunar Explorations Orbiter will carry an entire suite of innovative, complementary technologies, including high-resolution camera systems, several spectrometers that cover previously unexplored parts of the electromagnetic spectrum over a broad range of wavelengths, microwave and

  9. Analysis of medium-energy transfers to the Moon

    Science.gov (United States)

    Oshima, Kenta; Topputo, Francesco; Campagnola, Stefano; Yanao, Tomohiro

    2017-03-01

    This study analyzes a recently discovered class of exterior transfers to the Moon. These transfers terminate in retrograde ballistic capture orbits, i.e., orbits with negative Keplerian energy and angular momentum with respect to the Moon. Yet, their Jacobi constant is relatively low, for which no forbidden regions exist, and the trajectories do not appear to mimic the dynamics of the invariant manifolds of the Lagrange points. This paper shows that these orbits shadow instead lunar collision orbits. We investigate the dynamics of singular, lunar collision orbits in the Earth-Moon planar circular restricted three-body problem, and reveal their rich phase space structure in the medium-energy regime, where invariant manifolds of the Lagrange point orbits break up. We show that lunar retrograde ballistic capture trajectories lie inside the tube structure of collision orbits. We also develop a method to compute medium-energy transfers by patching together orbits inside the collision tube and those whose apogees are located in the appropriate quadrant in the Sun-Earth system. The method yields the novel family of transfers as well as those ending in direct capture orbits, under particular energetic and geometrical conditions.

  10. Science Planning and Orbit Classification for Solar Probe Plus

    Science.gov (United States)

    Kusterer, M. B.; Fox, N. J.; Rodgers, D. J.; Turner, F. S.

    2016-12-01

    There are a number of challenges for the Science Planning Team (SPT) of the Solar Probe Plus (SPP) Mission. Since SPP is using a decoupled payload operations approach, tight coordination between the mission operations and payload teams will be required. The payload teams must manage the volume of data that they write to the spacecraft solid-state recorders (SSR) for their individual instruments for downlink to the ground. Making this process more difficult, the geometry of the celestial bodies and the spacecraft during some of the SPP mission orbits cause limited uplink and downlink opportunities. The payload teams will also be required to coordinate power on opportunities, command uplink opportunities, and data transfers from instrument memory to the spacecraft SSR with the operation team. The SPT also intend to coordinate observations with other spacecraft and ground based systems. To solve these challenges, detailed orbit activity planning is required in advance for each orbit. An orbit planning process is being created to facilitate the coordination of spacecraft and payload activities for each orbit. An interactive Science Planning Tool is being designed to integrate the payload data volume and priority allocations, spacecraft ephemeris, attitude, downlink and uplink schedules, spacecraft and payload activities, and other spacecraft ephemeris. It will be used during science planning to select the instrument data priorities and data volumes that satisfy the orbit data volume constraints and power on, command uplink and data transfer time periods. To aid in the initial stages of science planning we have created an orbit classification scheme based on downlink availability and significant science events. Different types of challenges arise in the management of science data driven by orbital geometry and operational constraints, and this scheme attempts to identify the patterns that emerge.

  11. Periodic orbits for three and four co-orbital bodies

    Science.gov (United States)

    Verrier, P. E.; McInnes, C. R.

    2014-08-01

    We investigate the natural families of periodic orbits associated with the equilibrium configurations of the planar-restricted 1 + n-body problem for the case 2 ≤ n ≤ 4 equal-mass satellites. Such periodic orbits can be used to model both trojan exoplanetary systems and parking orbits for captured asteroids within the Solar system. For n = 2, there are two families of periodic orbits associated with the equilibria of the system: the well-known horseshoe and tadpole orbits. For n = 3, there are three families that emanate from the equilibrium configurations of the satellites, while for n = 4, there are six such families as well as numerous additional connecting families. The families of periodic orbits are all of the horseshoe or tadpole type, and several have regions of neutral linear stability.

  12. Periodic orbits for 3 and 4 co-orbital bodies

    CERN Document Server

    Verrier, Patricia

    2014-01-01

    We investigate the natural families of periodic orbits associated with the equilibrium configurations of the the planar restricted $1+n$ body problem for the case $2\\leq n \\leq 4$ equal mass satellites. Such periodic orbits can be used to model both trojan exoplanetary systems and parking orbits for captured asteroids within the solar system. For $n=2$ there are two families of periodic orbits associated with the equilibria of the system: the well known horseshoe and tadpole orbits. For $n=3$ there are three families that emanate from the equilibrium configurations of the satellites, while for $n=4$ there are six such families as well as numerous additional connecting families. The families of periodic orbits are all of the horseshoe or tadpole type, and several have regions of neutral linear stability.

  13. Orbital debris issues

    Science.gov (United States)

    Kessler, D. J.

    Orbital debris issues fall into three major topics: Environment Definition, Spacecraft Hazard, and Space Object Management. The major issue under Environment Definition is defining the debris flux for sizes smaller (10 cm in diameter) than those tracked by the North American Aerospace Defense Command (NORAD). Sources for this size debris are fragmentation of larger objects, either by explosion or collision, and solid rocket motor products. Modeling of these sources can predict fluxes in low Earth orbit which are greater than the meteoroid environment. Techniques to measure the environment in the size interval between 1 mm and 10 cm are being developed, including the use of telescopes and radar both on the ground and in space. Some impact sensors designed to detect meteoroids may have detected solid rocket motor products. Once the environment is defined, it can be combined with hypervelocity impact data and damage criteria to evaluate the Spacecraft Hazard. Shielding may be required to obtain an acceptable damage level. Space Object Management includes techniques to control the environment and the desired policy to effectively minimize the hazard to spacecraft. One control technique - reducing the likelihood of future explosions in space - has already been implemented by NASA. The effectiveness of other techniques has yet to be evaluated.

  14. MIT Orbital Transfer Vehicle (MOTV): CASTOR Satellite: Design Document

    Science.gov (United States)

    2010-11-18

    with Chocolate Satellite ................................................... 38 Figure 2.1-1: Ground System Layout...292 Figure 6.2-8: Analog Output Channels ........................................................................... 293 Figure 6.2-9: Turn PID Off...connections. Diagrams of the pin connections are included. The Grounding section identifies the type of grounding connections (i.e. analog , digital

  15. Molecular orbitals for properties and spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Robert, Vincent [Laboratoire de Chimie Quantique, Institut de Chimie, Université de Strasbourg, 1 rue Blaise Pascal 67000 Strasbourg-France (France); Domingo, Alex [Quantum Chemistry and Physical Chemistry Celestijnenlaan 200f, 3001 Heverlee - Belgium (Belgium); Braunstein, Pierre; Danopoulos, Andreas; Monakhov, Kirill [Laboratoire de Chimie de Coordination, Institut de Chimie, Université de Strasbourg, 4 rue Blaise Pascal 67081 Strasbourg-France (France)

    2015-12-31

    The description and clarification of spectroscopies and properties goes through ab initio calculations. Wave function based calculations (CASSCF/CASPT2) are particularly appealing since they offer spectroscopic accuracy and means of interpretation. we performed such calculations to elucidate the origin of unusual structural changes and intramolecular electron transfer phenomenon. Based on optimized molecular orbitals and a reading of the multireference wave function, it is suggested that intimate interactions are likely to considerably modify the standard pictures. A so-called PIMA (polarization-induced metalâĹŠarene) interaction similar to the more familiar anion-π interaction is responsible for a significant deviation from sp{sup 3} geometry and an energetic stabilization of 50 kJ/mol in Cr(II) benzyl organometallic complexes. In a similar fashion, it is proposed that the energetic profile of the IVCT (inter valence charge transfer) exhibits strong similarities to the Marcus’ theory, suggesting a response behaviour of the ensemble of electrons as electron transfer occurs in Fe{sup 2+}/Fe{sup 3+} bimetallic compound. The electronic reorganization induced by the IVCT process accounts for 11.8 eV, a very large effect that reduces the transfer energy down to 0.89 eV, in very good agreement with experiments.

  16. Orbital Maneuvering Vehicle (OMV) remote servicing kit

    Science.gov (United States)

    Brown, Norman S.

    1988-01-01

    With the design and development of the Orbital Maneuvering Vehicle (OMV) progressing toward an early 1990 initial operating capability (IOC), a new era in remote space operations will evolve. The logical progression to OMV front end kits would make available in situ satellite servicing, repair, and consummables resupply to the satellite community. Several conceptual design study efforts are defining representative kits (propellant tanks, debris recovery, module servicers); additional focus must also be placed on an efficient combination module servicer and consummables resupply kit. A remote servicer kit of this type would be designed to perform many of the early maintenance/resupply tasks in both nominal and high inclination orbits. The kit would have the capability to exchange Orbital Replacement Units (ORUs), exchange propellant tanks, and/or connect fluid transfer umbilicals. Necessary transportation system functions/support could be provided by interfaces with the OMV, Shuttle (STS), or Expendable Launch Vehicle (ELV). Specific remote servicer kit designs, as well as ground and flight demonstrations of servicer technology are necessary to prepare for the potential overwhelming need. Ground test plans should adhere to the component/system/breadboard test philosophy to assure maximum capability of one-g testing. The flight demonstration(s) would most likely be a short duration, Shuttle-bay experiment to validate servicer components requiring a micro-g environment.

  17. [Endoscopic approaches to the orbit].

    Science.gov (United States)

    Cebula, H; Lahlou, A; De Battista, J C; Debry, C; Froelich, S

    2010-01-01

    During the last decade, the use of endoscopic endonasal approaches to the pituitary has increased considerably. The endoscopic endonasal and transantral approaches offer a minimally invasive alternative to the classic transcranial or transconjunctival approaches to the medial aspect of the orbit. The medial wall of the orbit, the orbital apex, and the optic canal can be exposed through a middle meatal antrostomy, an anterior and posterior ethmoidectomy, and a sphenoidotomy. The inferomedial wall of the orbit can be also perfectly visualized through a sublabial antrostomy or an inferior meatal antrostomy. Several reports have described the use of an endoscopic approach for the resection or the biopsy of lesions located on the medial extraconal aspect of the orbit and orbital apex. However, the resection of intraconal lesions is still limited by inadequate instrumentation. Other indications for the endoscopic approach to the orbit are the decompression of the orbit for Graves' ophthalmopathy and traumatic optic neuropathy. However, the optimal management of traumatic optic neuropathy remains very controversial. Endoscopic endonasal decompression of the optic nerve in case of tumor compression could be a more valid indication in combination with radiation therapy. Finally, the endoscopic transantral treatment of blowout fracture of the floor of the orbit is an interesting option that avoids the eyelid or conjunctive incision of traditional approaches. The collaboration between the neurosurgeon and the ENT surgeon is mandatory and reduces the morbidity of the approach. Progress in instrumentation and optical devices will certainly make this approach promising for intraconal tumor of the orbit.

  18. 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

  19. Transfer Pricing

    DEFF Research Database (Denmark)

    Rohde, Carsten; Rossing, Christian Plesner

    trade internally as the units have to decide what prices should be paid for such inter-unit transfers. One important challenge is to uncover the consequences that different transfer prices have on the willingness in the organizational units to coordinate activities and trade internally. At the same time...

  20. Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Morgan, T.; Chin, G.

    2007-08-01

    NASA's Lunar Reconnaissance Orbiter (LRO) plans to launch in October 2008 with a companion secondary impactor mission, LCROSS, as the inaugural missions for the Exploration System Mission Directorate. LRO is a pathfinder whose objective is to obtain the needed information to prepare for eventual human return to the Moon. LRO will undertake at least one baseline year of operation with additional extended mission phase sponsored by NASA's Science Mission Directorate. LRO will employ six individual instruments to produce accurate maps and high-resolution images of future landing sites, to assess potential lunar resources, and to characterize the radiation environment. LRO will also test the feasibility of one advanced technology demonstration package. The LRO payload includes: Lunar Orbiter Laser Altimeter (LOLA) which will determine the global topography of the lunar surface at high resolution, measure landing site slopes, surface roughness, and search for possible polar surface ice in shadowed regions; Lunar Reconnaissance Orbiter Camera (LROC) which will acquire targeted narrow angle images of the lunar surface capable of resolving meter-scale features to support landing site selection, as well as wide-angle images to characterize polar illumination conditions and to identify potential resources; Lunar Exploration Neutron Detector (LEND) which will map the flux of neutrons from the lunar surface to search for evidence of water ice, and will provide space radiation environment measurements that may be useful for future human exploration; Diviner Lunar Radiometer Experiment (DLRE) which will chart the temperature of the entire lunar surface at approximately 300 meter horizontal resolution to identify cold-traps and potential ice deposits; Lyman-Alpha Mapping Project (LAMP) which will map the entire lunar surface in the far ultraviolet. LAMP will search for surface ice and frost in the polar regions and provide images of permanently shadowed regions illuminated only

  1. Orbital State Uncertainty Realism

    Science.gov (United States)

    Horwood, J.; Poore, A. B.

    2012-09-01

    Fundamental to the success of the space situational awareness (SSA) mission is the rigorous inclusion of uncertainty in the space surveillance network. The *proper characterization of uncertainty* in the orbital state of a space object is a common requirement to many SSA functions including tracking and data association, resolution of uncorrelated tracks (UCTs), conjunction analysis and probability of collision, sensor resource management, and anomaly detection. While tracking environments, such as air and missile defense, make extensive use of Gaussian and local linearity assumptions within algorithms for uncertainty management, space surveillance is inherently different due to long time gaps between updates, high misdetection rates, nonlinear and non-conservative dynamics, and non-Gaussian phenomena. The latter implies that "covariance realism" is not always sufficient. SSA also requires "uncertainty realism"; the proper characterization of both the state and covariance and all non-zero higher-order cumulants. In other words, a proper characterization of a space object's full state *probability density function (PDF)* is required. In order to provide a more statistically rigorous treatment of uncertainty in the space surveillance tracking environment and to better support the aforementioned SSA functions, a new class of multivariate PDFs are formulated which more accurately characterize the uncertainty of a space object's state or orbit. The new distribution contains a parameter set controlling the higher-order cumulants which gives the level sets a distinctive "banana" or "boomerang" shape and degenerates to a Gaussian in a suitable limit. Using the new class of PDFs within the general Bayesian nonlinear filter, the resulting filter prediction step (i.e., uncertainty propagation) is shown to have the *same computational cost as the traditional unscented Kalman filter* with the former able to maintain a proper characterization of the uncertainty for up to *ten

  2. Precise Orbit Determination for ALOS

    Science.gov (United States)

    Nakamura, Ryo; Nakamura, Shinichi; Kudo, Nobuo; Katagiri, Seiji

    2007-01-01

    The Advanced Land Observing Satellite (ALOS) has been developed to contribute to the fields of mapping, precise regional land coverage observation, disaster monitoring, and resource surveying. Because the mounted sensors need high geometrical accuracy, precise orbit determination for ALOS is essential for satisfying the mission objectives. So ALOS mounts a GPS receiver and a Laser Reflector (LR) for Satellite Laser Ranging (SLR). This paper deals with the precise orbit determination experiments for ALOS using Global and High Accuracy Trajectory determination System (GUTS) and the evaluation of the orbit determination accuracy by SLR data. The results show that, even though the GPS receiver loses lock of GPS signals more frequently than expected, GPS-based orbit is consistent with SLR-based orbit. And considering the 1 sigma error, orbit determination accuracy of a few decimeters (peak-to-peak) was achieved.

  3. Orbital Eccrine Hidrocystoma

    Directory of Open Access Journals (Sweden)

    Deniz Marangoz

    2016-10-01

    Full Text Available A 29-year-old female patient presented with a painless mass on her upper eyelid medially. She noticed the mass 4 years earlier and it had increased in size over time. She had no diplopia, eyelid swelling, skin lesion overlying the mass, or visual disturbances. On ocular examination, eye movements and funduscopy were normal. The mass was movable and painless with palpation. Magnetic resonance imaging with contrast showed a 12x8x7 mm well-circumscribed cystic lesion with no contrast dye appearance. Surgical removal was performed delicately and no capsular rupture occured. Pathological examination revealed an eccrine hidrocystoma. Our aim is to underline that eccrine hidrocystoma should be included in differential diagnosis of orbital masses.

  4. 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.

  5. Orbital angular momentum microlaser

    Science.gov (United States)

    Miao, Pei; Zhang, Zhifeng; Sun, Jingbo; Walasik, Wiktor; Longhi, Stefano; Litchinitser, Natalia M.; Feng, Liang

    2016-07-01

    Structured light provides an additional degree of freedom for modern optics and practical applications. The effective generation of orbital angular momentum (OAM) lasing, especially at a micro- and nanoscale, could address the growing demand for information capacity. By exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser producing a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. The polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Our OAM microlaser could find applications in the next generation of integrated optoelectronic devices for optical communications in both quantum and classical regimes.

  6. Orbital science's 'Bermuda Triangle'

    Science.gov (United States)

    Sherrill, Thomas J.

    1991-02-01

    The effects of a part of the inner Van Allen belt lying closest to the earth, known as the South Atlantic Anomaly (SAA) upon spacecraft including the Hubble Space Telescope (HST), are discussed. The area consists of positively charged ions and electrons from the Van Allen Belt which become trapped in the earth's dipole field. Contor maps representing the number of protons per square centimeter per second having energies greater than 10 million electron volts are presented. It is noted that the HST orbit causes it to spend about 15 percent of its time in the SAA, but that, unlike the experience with earlier spacecraft, the satellite's skin, internal structure, and normal electronic's packaging provides sufficient protection against eletrons, although some higher energy protons still get through. Various charged particle effects which can arise within scientific instruments including fluorescence, Cerenkov radiation, and induced radioactivity are described.

  7. Geology orbiter comparison study

    Science.gov (United States)

    Cutts, J. A. J.; Blasius, K. R.; Davis, D. R.; Pang, K. D.; Shreve, D. C.

    1977-01-01

    Instrument requirements of planetary geology orbiters were examined with the objective of determining the feasibility of applying standard instrument designs to a host of terrestrial targets. Within the basic discipline area of geochemistry, gamma-ray, X-ray fluorescence, and atomic spectroscopy remote sensing techniques were considered. Within the discipline area of geophysics, the complementary techniques of gravimetry and radar were studied. Experiments using these techniques were analyzed for comparison at the Moon, Mercury, Mars and the Galilean satellites. On the basis of these comparative assessments, the adaptability of each sensing technique was judged as a basic technique for many targets, as a single instrument applied to many targets, as a single instrument used in different mission modes, and as an instrument capability for nongeoscience objectives.

  8. Achieving Climate Change Absolute Accuracy in Orbit

    Science.gov (United States)

    Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C. O.; Bantges, R.; Best, F.; Bowman, K.; Brindley, H.; Butler, J. J.; Collins, W.; Dykema, J. A.; Doelling, D. R.; Feldman, D. R.; Fox, N.; Huang, X.; Holz, R.; Huang, Y.; Jennings, D.; Jin, Z.; Johnson, D. G.; Jucks, K.; Kato, S.; Kratz, D. P.; Liu, X.; Lukashin, C.; Mannucci, A. J.; Phojanamongkolkij, N.; Roithmayr, C. M.; Sandford, S.; Taylor, P. C.; Xiong, X.

    2013-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5-50 micron), the spectrum of solar radiation reflected by the Earth and its atmosphere (320-2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a "NIST [National Institute of Standards and Technology] in orbit." CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

  9. Orbit Determination Toolbox

    Science.gov (United States)

    Carpenter, James R.; Berry, Kevin; Gregpru. Late; Speckman, Keith; Hur-Diaz, Sun; Surka, Derek; Gaylor, Dave

    2010-01-01

    The Orbit Determination Toolbox is an orbit determination (OD) analysis tool based on MATLAB and Java that provides a flexible way to do early mission analysis. The toolbox is primarily intended for advanced mission analysis such as might be performed in concept exploration, proposal, early design phase, or rapid design center environments. The emphasis is on flexibility, but it has enough fidelity to produce credible results. Insight into all flight dynamics source code is provided. MATLAB is the primary user interface and is used for piecing together measurement and dynamic models. The Java Astrodynamics Toolbox is used as an engine for things that might be slow or inefficient in MATLAB, such as high-fidelity trajectory propagation, lunar and planetary ephemeris look-ups, precession, nutation, polar motion calculations, ephemeris file parsing, and the like. The primary analysis functions are sequential filter/smoother and batch least-squares commands that incorporate Monte-Carlo data simulation, linear covariance analysis, measurement processing, and plotting capabilities at the generic level. These functions have a user interface that is based on that of the MATLAB ODE suite. To perform a specific analysis, users write MATLAB functions that implement truth and design system models. The user provides his or her models as inputs to the filter commands. The software provides a capability to publish and subscribe to a software bus that is compliant with the NASA Goddard Mission Services Evolution Center (GMSEC) standards, to exchange data with other flight dynamics tools to simplify the flight dynamics design cycle. Using the publish and subscribe approach allows for analysts in a rapid design center environment to seamlessly incorporate changes in spacecraft and mission design into navigation analysis and vice versa.

  10. The conservation of orbital symmetry

    CERN Document Server

    Woodward, R B

    2013-01-01

    The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain-or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book ope

  11. Homogeneous orbit closures and applications

    CERN Document Server

    Lindenstrauss, Elon

    2011-01-01

    We give new classes of examples of orbits of the diagonal group in the space of unit volume lattices in R^d for d > 2 with nice (homogeneous) orbit closures, as well as examples of orbits with explicitly computable but irregular orbit closures. We give Diophantine applications to the former, for instance we show that if x is the cubic root of 2 then for any y,z in R liminf |n|=0 (as |n| goes to infinity), where denotes the distance of a real number c to the integers.

  12. Orbit Alignment in Triple Stars

    Science.gov (United States)

    Tokovinin, Andrei

    2017-08-01

    The statistics of the angle Φ between orbital angular momenta in hierarchical triple systems with known inner visual or astrometric orbits are studied. A correlation between apparent revolution directions proves the partial orbit alignment known from earlier works. The alignment is strong in triples with outer projected separation less than ∼50 au, where the average Φ is about 20^\\circ . In contrast, outer orbits wider than 1000 au are not aligned with the inner orbits. It is established that the orbit alignment decreases with the increasing mass of the primary component. The average eccentricity of inner orbits in well-aligned triples is smaller than in randomly aligned ones. These findings highlight the role of dissipative interactions with gas in defining the orbital architecture of low-mass triple systems. On the other hand, chaotic dynamics apparently played a role in shaping more massive hierarchies. The analysis of projected configurations and triples with known inner and outer orbits indicates that the distribution of Φ is likely bimodal, where 80% of triples have {{Φ }}< 70^\\circ and the remaining ones are randomly aligned.

  13. "Transfer Shock" or "Transfer Ecstasy?"

    Science.gov (United States)

    Nickens, John M.

    The alleged characteristic drop in grade point average (GPA) of transfer students and the subsequent rise in GPA was investigated in this study. No statistically significant difference was found in first term junior year GPA between junior college transfers and native Florida State University students after the variance accounted for by the…

  14. New orbit correction method uniting global and local orbit corrections

    Science.gov (United States)

    Nakamura, N.; Takaki, H.; Sakai, H.; Satoh, M.; Harada, K.; Kamiya, Y.

    2006-01-01

    A new orbit correction method, called the eigenvector method with constraints (EVC), is proposed and formulated to unite global and local orbit corrections for ring accelerators, especially synchrotron radiation(SR) sources. The EVC can exactly correct the beam positions at arbitrarily selected ring positions such as light source points, simultaneously reducing closed orbit distortion (COD) around the whole ring. Computer simulations clearly demonstrate these features of the EVC for both cases of the Super-SOR light source and the Advanced Light Source (ALS) that have typical structures of high-brilliance SR sources. In addition, the effects of errors in beam position monitor (BPM) reading and steering magnet setting on the orbit correction are analytically expressed and also compared with the computer simulations. Simulation results show that the EVC is very effective and useful for orbit correction and beam position stabilization in SR sources.

  15. 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.

  16. 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.

  17. Jovian Tour Design for Orbiter and Lander Missions to Europa

    Science.gov (United States)

    Campagnola, Stefano; Buffington, Brent B.; Petropoulos, Anastassios E.

    2013-01-01

    Europa is one of the most interesting targets for solar system exploration, as its ocean of liquid water could harbor life. Following the recommendation of the Planetary Decadal Survey, NASA commissioned a study for a flyby mission, an orbiter mission, and a lander mission. This paper presents the moon tours for the lander and orbiter concepts. The total delta v and radiation dose would be reduced by exploiting multi-body dynamics and avoiding phasing loops in the Ganymede-to- Europa transfer. Tour 11-O3, 12-L1 and 12-L4 are presented in details and their performaces compared to other tours from previous Europa mission studies.

  18. Orbital Debris Quarterly News. Volume 13; No. 1

    Science.gov (United States)

    Liou, J.-C. (Editor); Shoots, Debi (Editor)

    2009-01-01

    Topics discussed include: new debris from a decommissioned satellite with a nuclear power source; debris from the destruction of the Fengyun-1C meteorological satellite; quantitative analysis of the European Space Agency's Automated Transfer Vehicle 'Jules Verne' reentry event; microsatellite impact tests; solar cycle 24 predictions and other long-term projections and geosynchronus (GEO) environment for the Orbital Debris Engineering Model (ORDEM2008). Abstracts from the NASA Orbital Debris Program Office, examining satellite reentry risk assessments and statistical issues for uncontrolled reentry hazards, are also included.

  19. On-orbit operational scenarios, tools and techniques

    Science.gov (United States)

    Jennings, Jerry L.; Walker, James

    1991-01-01

    This paper concentrates on methods and techniques used to develop operational scenarios for orbital missions, including development of models to analyze alternatives, modification of tools and refinement of techniques for future missions. Many of these tools and techniques have been derived from previous tools, techniques and experience from the Orbital Maneuvering Vehicle (OMV) program. Results from use of these tools show the current Cargo Transfer Vehicle nominal mission scenario, with 95 discrete events defined for the CTV mission from the NLS Heavy Lift Launch Vehicle (HLLV) to Space Station Freedom (SSF).

  20. Orbital Maneuvering Vehicle (OMV) three-point docking latch

    Science.gov (United States)

    Myers, W. Neill; Forbes, John C.; Barnes, Wayne L.

    1990-01-01

    The primary purpose of the OMV is to dock with orbiting payloads and then either transfer them to a different orbit or return them to the Space Shuttle for servicing. Some such missions will involve docking with payloads equipped with a Flight Support System (FSS) type of interface; an example is the Hubble Space Telescope (HST). The design and development of a mechanism to be used for testing this docking concept on the NASA-Marshall test beds is described. The test results to date are also presented.

  1. Study of closed orbit response to magnet vibrations at the SSRF storage ring

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-Hui; ZHAO Zhen-Tang; DAI Zhi-Min; LIU Gui-Min

    2008-01-01

    This paper presents the analytical and simulation responses of the closed orbit distortion in the SSRF storage ring to random and plane wave like magnet vibrations respectively. It is shown that the use of girder is very beneficial in the view of suppressing this response function. Effect of the independently supported gradient bending magnets to the closed orbit response is given. An analytic formula is written to give a rough estimate of the closed orbit distortion due to ground motion, taking into account the closed orbit response function and girder transfer function. As an example, the result of SSRF case is given.

  2. Energy transfer in the solar system

    Science.gov (United States)

    Jelbring, H.

    2013-12-01

    Different types of energy transfer are presented from the literature and are approached and commented on. It follows from these articles that energy transfer in addition to solar irradiation is less well understood by contemporary scientist. The transformation of energy between kinetic and potential energy in planetary orbits might be of crucial importance for understanding energy transfer between celestial bodies and the development of commensurabilities. There is evidence pointing to interactions (friction) between space and satellites producing volcanism. The reversible transfer of energy between the orbit of Moon and Earth's rotational energy is crucial to the creation of the 13.6-day and 27.3-day periods in both solar variables and Earth bound climate variables. It is hypothesized that the Earth-Moon system is modulating the sunspot numbers and creating both these periods, and that the great planets are responsible for the 11 yr solar cycle.

  3. Fourier Series Approximations to J2-Bounded Equatorial Orbits

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-01-01

    Full Text Available The current paper offers a comprehensive dynamical analysis and Fourier series approximations of J2-bounded equatorial orbits. The initial conditions of heterogeneous families of J2-perturbed equatorial orbits are determined first. Then the characteristics of two types of J2-bounded orbits, namely, pseudo-elliptic orbit and critical circular orbit, are studied. Due to the ambiguity of the closed-form solutions which comprise the elliptic integrals and Jacobian elliptic functions, showing little physical insight into the problem, a new scheme, termed Fourier series expansion, is adopted for approximation herein. Based on least-squares fitting to the coefficients, the solutions are expressed with arbitrary high-order Fourier series, since the radius and the flight time vary periodically as a function of the polar angle. As a consequence, the solutions can be written in terms of elementary functions such as cosines, rather than complex mathematical functions. Simulations enhance the proposed approximation method, showing bounded and negligible deviations. The approximation results show a promising prospect in preliminary orbits design, determination, and transfers for low-altitude spacecrafts.

  4. Diplopia and orbital wall fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.

    2014-01-01

    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and su

  5. [Enophthalmos in an orbital tumor].

    Science.gov (United States)

    Szabo, Bianca; Szabo, I; Nicula, Cristina; Popescu, Livia Adriana

    2013-01-01

    Enophtalmus is an unusual sign of the orbital tumors often represented by proptosis. One patient with enophtalmus and intraorbital tumor and aplasy is presented. The treatment of choice of orbital tumor is complete surgical excision and careful follow-up. Considering the more aggressive course followed by recurrent tumor, correct diagnosis and management is essential.

  6. Diffractive molecular-orbital tomography

    Science.gov (United States)

    Zhai, Chunyang; Zhu, Xiaosong; Lan, Pengfei; Wang, Feng; He, Lixin; Shi, Wenjing; Li, Yang; Li, Min; Zhang, Qingbin; Lu, Peixiang

    2017-03-01

    High-order-harmonic generation in the interaction of femtosecond lasers with atoms and molecules opens the path to molecular-orbital tomography and to probe the electronic dynamics with attosecond-Ångström resolutions. Molecular-orbital tomography requires both the amplitude and phase of the high-order harmonics. Yet the measurement of phases requires sophisticated techniques and represents formidable challenges at present. Here we report a scheme, called diffractive molecular-orbital tomography, to retrieve the molecular orbital solely from the amplitude of high-order harmonics without measuring any phase information. We have applied this method to image the molecular orbitals of N2, CO2, and C2H2 . The retrieved orbital is further improved by taking account the correction of Coulomb potential. The diffractive molecular-orbital tomography scheme, removing the roadblock of phase measurement, significantly simplifies the molecular-orbital tomography procedure and paves an efficient and robust way to the imaging of more complex molecules.

  7. GridOrbit public display

    DEFF Research Database (Denmark)

    Ramos, Juan David Hincapie; Tabard, Aurélien; Bardram, Jakob

    2010-01-01

    We introduce GridOrbit, a public awareness display that visualizes the activity of a community grid used in a biology laboratory. This community grid executes bioin-formatics algorithms and relies on users to donate CPU cycles to the grid. The goal of GridOrbit is to create a shared awareness about...

  8. Diplopia and orbital wall fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.

    2014-01-01

    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and

  9. Low Earth Orbiter: Terminal

    Science.gov (United States)

    Kremer, Steven E.; Bundick, Steven N.

    1999-01-01

    In response to the current government budgetary environment that requires the National Aeronautics and Space Administration (NASA) to do more with less, NASA/Goddard Space Flight Center's Wallops Flight Facility has developed and implemented a class of ground stations known as a Low Earth Orbiter-Terminal (LEO-T). This development thus provides a low-cost autonomous ground tracking service for NASA's customers. More importantly, this accomplishment provides a commercial source to spacecraft customers around the world to purchase directly from the company awarded the NASA contract to build these systems. A few years ago, NASA was driven to provide more ground station capacity for spacecraft telemetry, tracking, and command (TT&C) services with a decreasing budget. NASA also made a decision to develop many smaller, cheaper satellites rather than a few large spacecraft as done in the past. In addition, university class missions were being driven to provide their own TT&C services due to the increasing load on the NASA ground-tracking network. NASA's solution for this ever increasing load was to use the existing large aperture systems to support those missions requiring that level of performance and to support the remainder of the missions with the autonomous LEO-T systems. The LEO-T antenna system is a smaller, cheaper, and fully autonomous unstaffed system that can operate without the existing NASA support infrastructure. The LEO-T provides a low-cost, reliable space communications service to the expanding number of low-earth orbiting missions around the world. The system is also fostering developments that improve cost-effectiveness of autonomous-class capabilities for NASA and commercial space use. NASA has installed three LEO-T systems. One station is at the University of Puerto Rico, the second system is installed at the Poker Flat Research Range near Fairbanks, Alaska, and the third system is installed at NASA's Wallops Flight Facility in Virginia. This paper

  10. Video Orbits of the Geminids

    Science.gov (United States)

    Hajdukova, M.

    2014-07-01

    Geminid meteoroids, observed by the video technique, were analysed with the aim of determining the actual dispersion of their reciprocal semimajor axes 1/a within the stream. Orbits were selected from the European Video Meteor Network Database, EDMOND, (Kornos et al., 2013), from the SonotaCo Shower Catalogue (SonotaCo, 2009), and from the Czech Catalogue of Video Meteor Orbits (Koten et al., 2003). The observed orbital dispersion, including the measurement errors, was compared with that obtained from the precisely-reduced photographic orbits of Geminids from the IAU Meteor Data Center (Lindblad et al., 2003). In this paper, we concentrate on the influence of errors on the orbital dispersion. The size and distribution of observational errors determined from the long-period meteoroid streams (Hajdukova 2013), were applied to determine the real dispersion within this short-period meteoroid stream. The observed dispersions, described by the median absolute deviation in terms of 1/a, range from 0.041 to 0.050 1/au. The deviation of the median reciprocal semimajor axis from the parent (3200) Phaethon, obtained from Japanese video orbits, is 0.009 1/au, and that from the EDMOND data 0.01 1/au. This deviation obtained from the photographic orbits of the IAU Meteor Data Center was significantly greater (Hajdukova 2009). Similar results were obtained from the Czech Video Orbits Catalogue, where the value is 0.05 1/au. The investigation showed that semimajor axes of meteor orbits in both the SonotaCo and EDMOND datasets are systematically biased as a consequence of the method used for the video orbit determination, probably because corrections for atmospheric deceleration were either incorrectly made or were not done at all. Thus, the determined heliocentric velocities are underestimated, and the semimajor axes medians shifted towards smaller values. The observed distributions in 1/a from these video data become biased towards higher values of 1/a. The orbits of the Geminid

  11. Measuring Scars of Periodic Orbits

    CERN Document Server

    Kaplan, L

    1999-01-01

    The phenomenon of periodic orbit scarring of eigenstates of classically chaotic systems is attracting increasing attention. Scarring is one of the most important ``corrections'' to the ideal random eigenstates suggested by random matrix theory. This paper discusses measures of scars and in so doing also tries to clarify the concepts and effects of eigenfunction scarring. We propose a new, universal scar measure which takes into account an entire periodic orbit and the linearized dynamics in its vicinity. This measure is tuned to pick out those structures which are induced in quantum eigenstates by unstable periodic orbits and their manifolds. It gives enhanced scarring strength as measured by eigenstate overlaps and inverse participation ratios, especially for longer orbits. We also discuss off-resonance scars which appear naturally on either side of an unstable periodic orbit.

  12. The 2009 Mars Telecommunications Orbiter

    Science.gov (United States)

    Wilson, G. R.; Depaula, R.; Diehl, R. E.; Edwards, C. D.; Fitzgerald, R. J.; Franklin, S. F.; Gibbs, R. G.; Kerridge, S. A.; Komarek, T. A.; Noreen, G. K.

    The first spacecraft with a primary function of providing communication links while orbiting a foreign planet has begun development for a launch in 2009. NASA's Mars Telecommunications Orbiter would use three radio bands to magnify the benefits of other future Mars missions and enable some types of missions otherwise impractical. It would serve as the Mars hub for a growing interplanetary Internet. And it would pioneer the use of planet-to-planet laser communications to demonstrate the possibility for even great networking capabilities in the future. During its nearly 10-year mission in orbit, Mars Telecommunications Orbiter would aid navigation of arriving spacecraft to their martian landing sites and monitor critical events during landings and orbit insertions. In addition, it would enable data-transmission volumes great enough to bring a virtual Mars presence to the public through a range of Internet and video features.

  13. Project ECHO: Electronic Communications from Halo Orbit

    Science.gov (United States)

    Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

    1994-01-01

    The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite

  14. VSOP-2 Orbit Determination

    Science.gov (United States)

    Takeuchi, H.; VSOP-2 Orbit Determination Sub-Working Group

    2009-08-01

    Precise orbit determination (POD) is a key factor to enable phase referencing observations with Astro-G. A POD accuracy of 30 cm is required for efficient X-band phase referencing observations, accuracy of 6 cm for K-band observations, and accuracy of 3 cm for Q-band observations. For the POD, Astro-G will be equipped with a GPS/Galileo receiver and a SLR (Satellite Laser Ranging) retroreflector array. Four POD antennas will be equipped on four sides of the satellite body, to cover all directions. The SLR will be used as a complement to the GPS at middle-to-high altitude. Because the refroreflector array should always face to the Earth direction, it will be set up on the Ka-link antenna gimbal. The most significant perturbing force for the Astro-G is solar radiation pressure (SRP). The reflectivity of each surface component should be preliminary measured in detail to model the SRP. The estimated achievable POD accuracy at apogee is 10 ˜ 30 cm in nominal case. Phase referencing observations in K- or Q-band can be performed if the enough amount of SLR tracking data can be obtained at high altitudes.

  15. Hydrogenoid orbitals revisited: From Slater orbitals to Coulomb Sturmians

    Indian Academy of Sciences (India)

    Danilo Calderini; Simonetta Cavalli; Cecilia Coletti; Gaia Grossi; Vincenzo Qquilanti

    2012-01-01

    The simple connection between the Slater orbitals, venerable in quantum chemistry, and the Coulomb Sturmian orbitals, more recently employed in atomic and molecular physics, is pointed out explicitly in view of the renewed interest in both as basis sets in applied quantum mechanics. Research in Slater orbitals mainly concerns multicentre, many-body integrals, whereas that on Sturmians exploits their orthonormality and completeness with no need of continuum states. An account of recent progress is outlined, also with reference to relationships between the two basis sets, and with the momentum space and hyperspherical harmonics representations.

  16. Heat transfer physics

    CERN Document Server

    Kaviany, Massoud

    2014-01-01

    This graduate textbook describes atomic-level kinetics (mechanisms and rates) of thermal energy storage, transport (conduction, convection, and radiation), and transformation (various energy conversions) by principal energy carriers. The approach combines the fundamentals of molecular orbitals-potentials, statistical thermodynamics, computational molecular dynamics, quantum energy states, transport theories, solid-state and fluid-state physics, and quantum optics. The textbook presents a unified theory, over fine-structure/molecular-dynamics/Boltzmann/macroscopic length and time scales, of heat transfer kinetics in terms of transition rates and relaxation times, and its modern applications, including nano- and microscale size effects. Numerous examples, illustrations, and homework problems with answers that enhance learning are included. This new edition includes applications in energy conversion (including chemical bond, nuclear, and solar), expanded examples of size effects, inclusion of junction quantum tr...

  17. 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

  18. Spin-inversion in nanoscale graphene sheets with a Rashba spin-orbit barrier

    Directory of Open Access Journals (Sweden)

    Somaieh Ahmadi

    2012-03-01

    Full Text Available Spin-inversion properties of an electron in nanoscale graphene sheets with a Rashba spin-orbit barrier is studied using transfer matrix method. It is found that for proper values of Rashba spin-orbit strength, perfect spin-inversion can occur in a wide range of electron incident angle near the normal incident. In this case, the graphene sheet with Rashba spin-orbit barrier can be considered as an electron spin-inverter. The efficiency of spin-inverter can increase up to a very high value by increasing the length of Rashba spin-orbit barrier. The effect of intrinsic spin-orbit interaction on electron spin inversion is then studied. It is shown that the efficiency of spin-inverter decreases slightly in the presence of intrinsic spin-orbit interaction. The present study can be used to design graphene-based spintronic devices.

  19. Circumbinary disk, an efficient medium extracting orbital angular momentum in close binaries

    Institute of Scientific and Technical Information of China (English)

    CHEN WenCong; ZENG QingGuo

    2009-01-01

    The loss of orbital angular momentum plays an important role in the mass transfer and orbital evolution of close binaries. The traditional mechanisms of orbital angular momentum loss consist of gravitational wave radiation, mass loss and magnetic braking. However, a small fraction of the mass outflow may form a thin circumbinary disk (CB disk) located in the orbital plane of the binary during mass exchange. The tide torques caused by the gravitational interaction between a CB disk and a binary system brake binary effectively, and extract the orbital angular momentum from the binary system. In this study, numerical calculations for the evolution of the white dwarf binary show that a CB disk is an efficient medium extracting orbital angular momentum even if the mass loss is very small. Finally, some theo-retical research and observational progress on CB disks are presented.

  20. SPHERES Mars Orbiting Sample Return External Orbiting Capture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's Mars Sample Return (MSR) mission scenario utilizes a small Orbiting Sample (OS) satellite, launched from the surface of Mars, which will rendezvous with an...

  1. 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.

  2. [Orbital tumor emergencies in childhood].

    Science.gov (United States)

    Morax, S; Desjardins, L

    2009-05-01

    Emergencies in childhood orbital tumorals are rare. The absolute emergency involves malignant primary orbital tumors, such as rhabdomyosarcoma or secondary malignant tumors (metastatic neuroblastoma, leukemia), involving a vital prognosis requiring prompt diagnosis. Delayed emergencies are usually vascular lesions. Among these lesions, immature orbital hemangioma, with a good prognosis, must be distinguished from orbital adnexal lymphangiomas, which are less frequent but can lead to dramatic cosmetic and functional disorders. In rare cases, they can be responsible for sudden, painful proptosis, due to orbital hemorrhage, with a risk of optic nerve compression, requiring emergency surgical treatment. Neurogenous lesions, either isolated, such as in gliomas, or associated with a systemic disease, such as Recklinghausen neurofibromatosis, threaten the functional prognosis. Diagnosis of pediatric orbital tumors is based on a good clinical examination, precise imaging investigations, and evaluation of the locoregional extension of the tumor. Biopsy is required in emergency situations, when rhabdomyosarcoma is suspected, in order to start the chemotherapy. However, the biopsy can be superfluous, and even useless or dangerous, when clinical and imaging investigations are sufficient to provide a diagnosis of capillary hemangioma, lymphangioma, or metastatic tumor from an abdominal malignancy. Treatment is closely related to the etiopathogenesis of the tumor. The outcomes are vital, functional and cosmetic. They may require orbital surgery (biopsy, tumoral resection, orbital decompression in case of a compressive hemorrhage), systemic corticotherapy (as in immature adnexal hemangioma), radiation, and chemotherapy (rhabdomyosarcoma, secondary malignant tumor). These diseases require a pediatric ophthalmological medical center specializing in orbital surgery, with close collaboration of multiple specialists such as onco-pediatricians and neurosurgeons.

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

    Science.gov (United States)

    Song, Young-Joo; Bae, Jonghee; Kim, Young-Rok; Kim, Bang-Yeop

    2016-12-01

    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 control center

  4. Technology Transfer

    Science.gov (United States)

    Smith, Nanette R.

    1995-01-01

    The objective of this summer's work was to attempt to enhance Technology Application Group (TAG) ability to measure the outcomes of its efforts to transfer NASA technology. By reviewing existing literature, by explaining the economic principles involved in evaluating the economic impact of technology transfer, and by investigating the LaRC processes our William & Mary team has been able to lead this important discussion. In reviewing the existing literature, we identified many of the metrics that are currently being used in the area of technology transfer. Learning about the LaRC technology transfer processes and the metrics currently used to track the transfer process enabled us to compare other R&D facilities to LaRC. We discuss and diagram impacts of technology transfer in the short run and the long run. Significantly, it serves as the basis for analysis and provides guidance in thinking about what the measurement objectives ought to be. By focusing on the SBIR Program, valuable information regarding the strengths and weaknesses of this LaRC program are to be gained. A survey was developed to ask probing questions regarding SBIR contractors' experience with the program. Specifically we are interested in finding out whether the SBIR Program is accomplishing its mission, if the SBIR companies are providing the needed innovations specified by NASA and to what extent those innovations have led to commercial success. We also developed a survey to ask COTR's, who are NASA employees acting as technical advisors to the SBIR contractors, the same type of questions, evaluating the successes and problems with the SBIR Program as they see it. This survey was developed to be implemented interactively on computer. It is our hope that the statistical and econometric studies that can be done on the data collected from all of these sources will provide insight regarding the direction to take in developing systematic evaluations of programs like the SBIR Program so that they can

  5. Ocular complications of orbital venography.

    Science.gov (United States)

    Safer, J N; Guibor, P

    1975-03-01

    Three ocular complications directly related to orbital venography are described, one resulting in permanent loss of vision,. The patient had lymphangioma of the orbit which evidently had bled secondary to increased venous pressure and injection of contrast bolus. Both of the 2 patients with transient visual disturbances had diabetic retinopathy. The common factor is felt to be an imparied vascular bed which cannot meet the stress of increased venous pressure and contrast medium injection. Conditions which predispose to ocular-orbital stasis and/or hemorrhage are discussed.

  6. Fusion-Enabled Pluto Orbiter and Lander

    Science.gov (United States)

    Thomas, Stephanie

    2017-01-01

    The Pluto orbiter mission proposed here is credible and exciting. The benefits to this and all outer-planet and interstellar-probe missions are difficult to overstate. The enabling technology, Direct Fusion Drive, is a unique fusion engine concept based on the Princeton Field-Reversed Configuration (PFRC) fusion reactor under development at the Princeton Plasma Physics Laboratory. The truly game-changing levels of thrust and power in a modestly sized package could integrate with our current launch infrastructure while radically expanding the science capability of these missions. During this Phase I effort, we made great strides in modeling the engine efficiency, thrust, and specific impulse and analyzing feasible trajectories. Based on 2D fluid modeling of the fusion reactors outer stratum, its scrape-off-layer (SOL), we estimate achieving 2.5 to 5 N of thrust for each megawatt of fusion power, reaching a specific impulse, Isp, of about 10,000 s. Supporting this model are particle-in-cell calculations of energy transfer from the fusion products to the SOL electrons. Subsequently, this energy is transferred to the ions as they expand through the magnetic nozzle and beyond. Our point solution for the Pluto mission now delivers 1000 kg of payload to Pluto orbit in 3.75 years using 7.5 N constant thrust. This could potentially be achieved with a single 1 MW engine. The departure spiral from Earth orbit and insertion spiral to Pluto orbit require only a small portion of the total delta-V. Departing from low Earth orbit reduces mission cost while increasing available mission mass. The payload includes a lander, which utilizes a standard green propellant engine for the landing sequence. The lander has about 4 square meters of solar panels mounted on a gimbal that allows it to track the orbiter, which beams 30 to 50 kW of power using a 1080 nm laser. Optical communication provides dramatically high data rates back to Earth. Our mass modeling investigations revealed that if

  7. Blastocyst Transfer

    OpenAIRE

    sprotocols

    2014-01-01

    ### Method: Blastocyst transfer is usually performed 24 hours after aggregation when the morulae have become expanded blastocysts and on the same day as injection. A little time is given between injection and transfer to allow blastocysts to re-expand. **The Recipient** Careful selection of the recipient is most important as the pups are the end result of a lot of hard work. Two strains of mice are used:RB Swiss and (CBA*C57BL6/J)f1. RB Swiss are quiet and make excellent mothers ...

  8. Heat transfer

    CERN Document Server

    Holman, J P

    2010-01-01

    As one of the most popular heat transfer texts, Jack Holman's "Heat Transfer" is noted for its clarity, accessible approach, and inclusion of many examples and problem sets. The new tenth edition retains the straight-forward, to-the-point writing style while covering both analytical and empirical approaches to the subject. Throughout the book, emphasis is placed on physical understanding while, at the same time, relying on meaningful experimental data in those situations that do not permit a simple analytical solution. New examples and templates provide students with updated resources for computer-numerical solutions.

  9. Thermodynamic, kinetic and electronic structure aspects of a charge-transfer active bichromophoric organofullerene

    Indian Academy of Sciences (India)

    K Senthil Kumar; Archita Patnaik

    2013-03-01

    Our recent work on charge transfer in the electronically push-pull dimethylaminoazobenzene-fullerene C60 donor-bridge-acceptor dyad through orbital picture revealed charge displacement from the n(N=N) (non-bonding) and (N=N) type orbitals centred on the donor part to the purely fullerene centred LUMOs and (LUMO+n) orbitals, delocalized over the entire molecule. Consequently, this investigation centres around the kinetic and thermodynamic parameters involved in the solvent polarity dependent intramolecular photo-induced electron transfer processes in the dyad, indispensable for artificial photosynthetic systems. A quasi-reversible electron transfer pathway was elucidated with electrode-specific heterogeneous electron transfer rate constants.

  10. Space Shuttle orbiter trimmed center-of-gravity extension study

    Science.gov (United States)

    Scallion, W. I.; Phillips, W. P.

    1985-01-01

    Aerodynamic, heat transfer, and system design studies to determine removable modifications for the Space Shuttle orbiter that would extend its forward center-of-gravity triom capability are summarized. Wind-tunnel tests were conducted at Mach numbers ranging from 0.25 to 20.3 to determine the most effective aerodynamic modifications. Heat transfer and system design studies determined the impact of the modifications on the thermal protection system and structural weight of the vehicle. The most effective modifications were in-fillet canards or a forward extension of the existing forward wing fillet.

  11. CODIMENSION 3 BIFURCATIONS OF HOMOCLINIC ORBITS WITH ORBIT FLIPS AND INCLINATION FLIPS

    Institute of Scientific and Technical Information of China (English)

    SHUI SHULIANG; ZHU DEMING

    2004-01-01

    The homoclinic bifurcations in four dimensional vector fields are investigated by setting up a local coordinates near the homoclinic orbit. This homoclinic orbit is nonprincipal in the meanings that its positive semi-orbit takes orbit flip and its unstable foliation takes inclination flip. The existence, nonexistence, uniqueness and coexistence of the 1-homoclinic orbit and the 1-periodic orbit are studied. The existence of the twofold periodic orbit and three-fold periodic orbit are also obtained.

  12. Local pair natural orbitals for excited states.

    Science.gov (United States)

    Helmich, Benjamin; Hättig, Christof

    2011-12-07

    We explore how in response calculations for excitation energies with wavefunction based (e.g., coupled cluster) methods the number of double excitation amplitudes can be reduced by means of truncated pair natural orbital (PNO) expansions and localized occupied orbitals. Using the CIS(D) approximation as a test model, we find that the number of double excitation amplitudes can be reduced dramatically with minor impact on the accuracy if the excited state wavefunction is expanded in state-specific PNOs generated from an approximate first-order guess wavefunction. As for ground states, the PNO truncation error can also for excitation energies be controlled by a single threshold related to generalized natural occupation numbers. The best performance is found with occupied orbitals which are localized by the Pipek-Mezey localization. For a large test set of excited states we find with this localization that already a PNO threshold of 10(-8)-10(-7), corresponding to an average of only 40-80 PNOs per pair, is sufficient to keep the PNO truncation error for vertical excitation energies below 0.01 eV. This is a significantly more rapid convergence with the number doubles amplitudes than in domain-based local response approaches. We demonstrate that the number of significant excited state PNOs scales asymptotically linearly with the system size in the worst case of completely delocalized excitations and sub-linearly whenever the chromophore does not increase with the system size. Moreover, we observe that the flexibility of state-specific PNOs to adapt to the character of an excitation allows for an almost unbiased treatment of local, delocalized and charge transfer excited states.

  13. Local pair natural orbitals for excited states

    Science.gov (United States)

    Helmich, Benjamin; Hättig, Christof

    2011-12-01

    We explore how in response calculations for excitation energies with wavefunction based (e.g., coupled cluster) methods the number of double excitation amplitudes can be reduced by means of truncated pair natural orbital (PNO) expansions and localized occupied orbitals. Using the CIS(D) approximation as a test model, we find that the number of double excitation amplitudes can be reduced dramatically with minor impact on the accuracy if the excited state wavefunction is expanded in state-specific PNOs generated from an approximate first-order guess wavefunction. As for ground states, the PNO truncation error can also for excitation energies be controlled by a single threshold related to generalized natural occupation numbers. The best performance is found with occupied orbitals which are localized by the Pipek-Mezey localization. For a large test set of excited states we find with this localization that already a PNO threshold of 10-8-10-7, corresponding to an average of only 40-80 PNOs per pair, is sufficient to keep the PNO truncation error for vertical excitation energies below 0.01 eV. This is a significantly more rapid convergence with the number doubles amplitudes than in domain-based local response approaches. We demonstrate that the number of significant excited state PNOs scales asymptotically linearly with the system size in the worst case of completely delocalized excitations and sub-linearly whenever the chromophore does not increase with the system size. Moreover, we observe that the flexibility of state-specific PNOs to adapt to the character of an excitation allows for an almost unbiased treatment of local, delocalized and charge transfer excited states.

  14. Electron vortices: Beams with orbital angular momentum

    Science.gov (United States)

    Lloyd, S. M.; Babiker, M.; Thirunavukkarasu, G.; Yuan, J.

    2017-07-01

    The recent prediction and subsequent creation of electron vortex beams in a number of laboratories occurred after almost 20 years had elapsed since the recognition of the physical significance and potential for applications of the orbital angular momentum carried by optical vortex beams. A rapid growth in interest in electron vortex beams followed, with swift theoretical and experimental developments. Much of the rapid progress can be attributed in part to the clear similarities between electron optics and photonics arising from the functional equivalence between the Helmholtz equations governing the free-space propagation of optical beams and the time-independent Schrödinger equation governing freely propagating electron vortex beams. There are, however, key differences in the properties of the two kinds of vortex beams. This review is primarily concerned with the electron type, with specific emphasis on the distinguishing vortex features: notably the spin, electric charge, current and magnetic moment, the spatial distribution, and the associated electric and magnetic fields. The physical consequences and potential applications of such properties are pointed out and analyzed, including nanoparticle manipulation and the mechanisms of orbital angular momentum transfer in the electron vortex interaction with matter.

  15. Thermal orbital injuries from disposable cauteries.

    Science.gov (United States)

    Liu, D; Stasior, O G

    1984-07-01

    Forty rabbits divided in six groups and three brands of hot wire cautery with temperature ranging from 190 degrees C to 1035 degrees C were used in this experiment. A surgical procedure resembling a cosmetic blepharoplasty was performed on a total of 60 lower eyelids of the rabbits. The remaining eyelids were either shams or normal controls. Cautery application to orbital fat was carefully controlled, i.e., 10 or 20 seconds in single or double applications. Gross observation and microscopic examination of the biopsied specimens taken at 3 hours, 2 days, and 2 weeks after the procedures were performed. Evidence of thermal injury to the lacrimal gland and extraocular muscle damage was found. Although no evidence of thermal injury to the optic nerve was found, it was conceivable that either by a direct transfer of heat or by an indirect inflammatory and compressive effect the health of the optic nerve might be threatened. It is strongly recommended that hot wire cautery be used with extreme caution when working with orbital tissues.

  16. Transfer Timing

    OpenAIRE

    2003-01-01

    sim present Simulation Presentation Interactive Media Element This IME is used in the Computer Communications and Networks class offered in the Graduate School of Operations and Information Sciences. This introductory computer networking course provides the theory and principles of networking and communications protocols. This IME is used to help students understand data transfer options. CS3502 Computer Communications and Networks

  17. Sophisticated transfer

    NARCIS (Netherlands)

    Reinhart, T.

    2006-01-01

    On the eve of the Iraq war, fears were expressed in different circles that under the cover of war, Israel may attempt a transfer of Palestinians in the “seam line” area of the northern West Bank (Kalkilya, Tulkarem). Last week, the army produced a scene from this scenario. On April 2 at 3 AM, a larg

  18. Real and Hybrid Atomic Orbitals.

    Science.gov (United States)

    Cook, D. B.; Fowler, P. W.

    1981-01-01

    Demonstrates that the Schrodinger equation for the hydrogenlike atom separates in both spheroconal and prolate spheroidal coordinates and that these separations provide a sound theoretical basis for the real and hybrid atomic orbitals. (Author/SK)

  19. [Orbital metastasis in malignant melanoma].

    Science.gov (United States)

    Pedroli, G L; Hamedani, M; Barraco, P; Oubaaz, A; Morax, S

    2001-03-01

    We report the case of a 60-year-old man presenting bilateral progressive proptosis with diplopia, weight loss, tachycardia, nervosity, and stomach pain. These signs seemed at first to favor a diagnosis of Graves'ophthalmopathy. Thyroid tests were negative and the initial orbital CT scan was considered normal. A new radiological investigation 4 months later in our hospital revealed typical hypertrophy of the extraocular muscles compatible with orbital metastasis. The systemic investigations demonstrated a pulmonary tumor, multiple hepatic lesions, and several pigmented nodules of gastric mucosa. The pathology of pulmonary and gastric specimens confirmed the diagnosis of malignant melanoma. The primary lesion remains unknown. The authors discuss the differential diagnoses of orbital metastasis and the radiological characteristics of orbital metastasis in malignant melanoma.

  20. Quark spin-orbit correlations

    CERN Document Server

    Lorcé, Cédric

    2014-01-01

    The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton spin-orbit correlation. We showed that this quantity can be expressed in terms of moments of measurable parton distributions. Using the available phenomenological information about the valence quarks, we concluded that this correlation is negative, meaning that the valence quark spin and kinetic orbital angular momentum are, in average, opposite. The quark spin-orbit correlation can also be expressed more intuitively in terms of relativistic phase-space distributions, which can be seen as the mother distributions of the standard generalized and transverse-momentum dependent parton distributions. We present here for the first time some examples of the general multipole decomposition of these phase-space distributions.

  1. ORBITAL MANIFESTATIONS OF SINUS DISEASE

    Directory of Open Access Journals (Sweden)

    Jyothirmayi

    2015-01-01

    Full Text Available AIM : To study the orbital manifestations in patients with sinus disease. METHODS : Patients wit h paranasal sinus disease presenting to OPD at Government ENT Hospital, AMC, Visakhapatnam from January 2012 to June 2014 were screened for orbital manifestations. Out of these, thirteen patients with orbital disease were referred to GREH, AMC, Visakhapatn am and were thoroughly investigated and managed appropriately. RESULTS : Out of the 14 patients 4 were female and 10 were male. Age ranged from 19 years to 70 years. 5 had maxillary sinus disease (4 - carcinoma and 1 case of mucormycosis. Frontal sinus dis ease was seen in two patients, one fibrous dysplasia and one malignancy. Five patients had ethmoidal sinus disease of which three patients were found to have ethmoidal sinus tumour (Malignant melanoma, Squamous cell Carcinoma. More than two sinuses were i nvolved in 2 patients. CONCLUSIONS : Early screening of patients with sinus disease by an Ophthalmologist can help in preventing severe vision threatening orbital complications.

  2. Closed Orbits in Phase Space

    Science.gov (United States)

    Murphy, Andrew; Haestad, Jace; Morgan, Thomas

    2015-09-01

    We report characteristics of closed classical orbits in an electric field in phase space produced in photoabsorption. Rydberg states of atomic and molecular hydrogen and helium are considered. The core potential used for the hydrogen molecule is an effective one electron one center core potential evaluated at the internuclear equilibrium distance. Poincare surfaces of section in phase space are generated by integrating the equations of motion in semiparabolic coordinates u = (r + z) 1 / 2 and v = (r - z) 1 / 2, and plotting the location in phase space (pv versus v) whenever u = 0, with the electric field in the z direction. Combination orbits produced by Rydberg electron core scattering are studied and the evolution in phase space of these combination orbits due to scattering from one closed orbit into another is investigated. Connections are made to measured laser photoabsorption experiments that excite Rydberg states (20 recurrence spectra. The phase space structures responsible for the spectra are identified.

  3. A Case of Orbital Histoplasmosis.

    Science.gov (United States)

    Krakauer, Mark; Prendes, Mark Armando; Wilkes, Byron; Lee, Hui Bae Harold; Fraig, Mostafa; Nunery, William R

    2016-01-01

    Histoplasma capsulatum var capsulatum is a dimorphic fungus endemic to the Ohio and Mississippi River Valleys of the United States. In this case report, a 33-year-old woman who presented with a right orbital mass causing progressive vision loss, diplopia, and facial swelling is described. Lateral orbitotomy with lateral orbital wall bone flap was performed for excisional biopsy of the lesion. The 1.5 × 1.8 × 2.3 cm cicatricial mass demonstrated a granulomatous lesion with necrosis and positive staining consistent with Histoplasma capsulatum var capsulatum infection. To the authors' knowledge, this is the first case of orbital histoplasmosis to be reported in the United States and the first case worldwide of orbital histoplasmosis due to Histoplasma capsulatum var capsulatum.

  4. Formation around planetary displaced orbit

    Institute of Scientific and Technical Information of China (English)

    GONG Sheng-ping; LI Jun-feng; BAOYIN He-xi

    2007-01-01

    The paper investigates the relative motion around the planetary displaced orbit. Several kinds of displaced orbits for geocentric and martian cases were discussed. First, the relative motion was linearized around the displaced orbits. Then, two seminatural control laws were investigated for each kind of orbit and the stable regions were obtained for each case. One of the two control laws is the passive control law that is very attractive for engineering practice. However, the two control laws are not very suitable for the Martian mission. Another special semi-natural control law is designed based on the requirement of the Martian mission. The results show that large stable regions exist for the control law.

  5. Orbital entanglement in quantum chemistry

    CERN Document Server

    Boguslawski, Katharina

    2014-01-01

    The basic concepts of orbital entanglement and its application to chemistry are briefly reviewed. The calculation of orbital entanglement measures from correlated wavefunctions is discussed in terms of reduced $n$-particle density matrices. Possible simplifications in their evaluation are highlighted in case of seniority-zero wavefunctions. Specifically, orbital entanglement allows us to dissect electron correlation effects in its strong and weak contributions, to determine bond orders, to assess the quality and stability of active space calculations, to monitor chemical reactions, and to identify points along the reaction coordinate where electronic wavefunctions change drastically. Thus, orbital entanglement represents a useful and intuitive tool to interpret complex electronic wavefunctions and to facilitate a qualitative understanding of electronic structure and how it changes in chemical processes.

  6. How to Orbit the Earth.

    Science.gov (United States)

    Quimby, Donald J.

    1984-01-01

    Discusses the geometry, algebra, and logic involved in the solution of a "Mindbenders" problem in "Discover" magazine and applies it to calculations of satellite orbital velocity. Extends the solution of this probe to other applications of falling objects. (JM)

  7. Orbital mechanics near Lagrange's points

    OpenAIRE

    Utashima, Masayoshi; 歌島 昌由

    1997-01-01

    The first libration-point satellite ISEE-3 (International Sun-Earth Explorer-3) was launched in 1978. Though, no libration-point satellites were realized after the launch of the ISEE-3, NASA launched the ESA's Solar and Heliospheric Observatory (SOHO) spacecraft into the halo orbit in the sun-earth system in late 1995. The halo orbit in the sun-earth system is adequate for missions such as solar observation, astronomical observation, NEO (Near Earth Objects) observation, communications with t...

  8. Orbit Determination Analysis for SSAPurposes

    OpenAIRE

    2015-01-01

    Space Situational Awareness (SSA) is the characterization of the space environmentand of space activities. The fundament of SSA is the access to information about theorbit of space objects. There exist several techniques to determine the orbit of objects inspace, both from space-based and from ground-based observations. This Master's Thesisproject aims at investigating orbit determinations from ground-based radar observations.In particular, the use of the EISCAT Ultra-High-Frequency (UHF) inc...

  9. Orbits in a logarithmic potential

    Energy Technology Data Exchange (ETDEWEB)

    Hooverman, R. H.

    2014-04-15

    The characteristics of charged particle orbits in the logarithmic electrostatic potential field surrounding a straight conducting wire at a fixed potential are investigated. The equations of motion of an electron in a logarithmic potential are derived, the limiting cases are considered, and the results of numerical integration of the equations of motion are presented along with sketches of a few representative orbits. (C.E.S.)

  10. Diplopia and orbital wall fractures.

    Science.gov (United States)

    Boffano, Paolo; Roccia, Fabio; Gallesio, Cesare; Karagozoglu, K Hakki; Forouzanfar, Tymour

    2014-01-01

    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and such fractures. This study is based on 2 databases that have continuously recorded data of patients hospitalized with maxillofacial fractures between 2001 and 2010. On the whole, 447 patients (334 males, 113 females) with pure blow-out orbital wall fractures were included. The most frequently involved orbital site was the floor (359 fractures), followed by medial wall (41 fractures) and lateral wall (5 fractures). At presentation, 227 patients (50.7%) had evidence of diplopia. In particular, in most patients, a diplopia in all directions was referred (78 patients). Statistically significant associations were found between diplopia on eye elevation and orbital floor fractures (P diplopia and medial wall fractures (P diplopia on eye elevation and horizontal diplopia at presentation could be useful clinical indicators orbital floor and medial wall fractures, respectively.

  11. Microbiological profile of orbital abscess

    Directory of Open Access Journals (Sweden)

    N Suneetha

    2012-01-01

    Full Text Available Background: Knowledge of the culture and sensitivity pattern is necessary, for the institution of appropriate empirical antibiotic therapy in orbital abscess. Objective: The objective of this study is to describe culture and sensitivity patterns of specimens from the orbit and surrounding structures. Materials and Methods: Retrospectively the medical records of 56 cases of orbital abscess were reviewed. Results: Cultures were positive in 38/56 (68.8% orbital specimens and the organisms included Staphylococcus aureus 18, Streptococci 7, Pseudomonas aeruginosa 3, 2 each of Enterobactersp, Escherichia coli, Proteus mirabilis, Acinetobacter sp. and 1 each of Actinomyces israelii, Diptheroids, Coagulase negative Staphylococcus, Citrobacter freundii, Methicillin-resistant S. aureus and Enterococcus faecalis. Four had polymicrobial infection. Culture of purulent nasal discharge, swabs taken from foci of infection on the face, and blood cultures were done in 26/56, and positive cultures were obtained in 16/26 (61.5% specimens. In 12 patients, there was a concurrence in the organism cultured from the orbit and from cultures from other sites. Gram-negative organisms were associated with increased ocular morbidity. Conclusion: Gram-positive cocci, especially S. aureus are the most common organisms isolated from orbital abscesses. Infections by Gram-negative organisms were associated with more complications. Empirical intravenous antibiotic therapy should have a broad spectrum of activity effective against a wide range of Staphylococcal organisms and Gram-negative bacilli.

  12. Low Earth orbit communications satellite

    Science.gov (United States)

    Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

    1992-01-01

    A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

  13. Orbital Volumetry in Graves' Orbitopathy

    DEFF Research Database (Denmark)

    Al-Bakri, Moug; Rasmussen, Åse Krogh; Thomsen, Carsten

    2014-01-01

    .6 cm(3) in controls, 8.7 ± 8.0 cm(3) in GO without DON, and 9.4 ± 3.1 cm(3) in GO with DON. The muscle and fat volumes were higher in patients with GO than in controls (P orbits with and without DON were not significantly different. The volume of the optic nerve were...... similar in the 3 groups. The number of apical, coronal 2 mm thick slices with no fat was 2.9 ± 0.9 in normal orbits, it was 4.1 ± 1.0 in GO orbits without DON and 5.3 ± 0.8 in GO orbits with DON (P = 0.007). Conclusion. Apical muscle enlargement may be more important than orbital fat enlargement......Purpose. We wanted to investigate the relative significance of fat and muscle enlargement in the development of dysthyroid optic neuropathy (DON) in Graves' orbitopathy (GO). Methods. Preoperative coronal CT scans of 13 patients with and without DON who subsequently underwent orbital decompression...

  14. Trajectory Design from GTO to Near-Equatorial Lunar Orbit for the Dark Ages Radio Explorer (DARE) Spacecraft

    Science.gov (United States)

    Genova, Anthony L.; Yang Yang, Fan; Perez, Andres Dono; Galal, Ken F.; Faber, Nicolas T.; Mitchell, Scott; Landin, Brett; Burns, Jack O.

    2015-01-01

    The trajectory design for the Dark Ages Radio Explorer (DARE) mission concept involves launching the DARE spacecraft into a geosynchronous transfer orbit (GTO) as a secondary payload. From GTO, the spacecraft then transfers to a lunar orbit that is stable (i.e., no station-keeping maneuvers are required with minimum perilune altitude always above 40 km) and allows for more than 1,000 cumulative hours for science measurements in the radio-quiet region located on the lunar farside.

  15. Space Tourism: Orbital Debris Considerations

    Science.gov (United States)

    Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

    2002-01-01

    Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a

  16. Orbital, subconjunctival, and subcutaneous emphysema after an orbital floor fracture

    Directory of Open Access Journals (Sweden)

    Ababneh OH

    2013-06-01

    Full Text Available Osama H Ababneh Department of Ophthalmology, The University of Jordan and Jordan University Hospital, Amman, Jordan Abstract: A 16-year-old boy presented to the emergency department with the complaint of a sudden, painful left eye and proptosis after an episode of sneezing. A few hours earlier, he had sustained a blunt trauma to the left orbit as the result of a fistfight. The initial examination showed subcutaneous and subconjunctival emphysema. Visual acuity in the left eye was 20/30 (0.67, the pupils were reactive with no relative afferent pupillary defect, and there were mild limitations in levoduction and supraduction. A slit-lamp examination showed normal anterior and posterior segments with an intraocular pressure of 26 mmHg. An orbital computed tomography scan showed orbital, subconjunctival, and subcutaneous emphysema associated with a small fracture of the orbital floor. Following conservative management with broad-spectrum oral antibiotics, a topical antiglaucoma drug, and lubricating eye drops, the patient improved dramatically within one week. Keywords: emphysema, orbital fracture, trauma

  17. Charge transfer and emergent phenomena of oxide heterostructures

    Science.gov (United States)

    Chen, Hanghui

    Charge transfer is a common phenomenon at oxide interfaces. We use first-principles calculations to show that via heterostructuring of transition metal oxides, the electronegativity difference between two dissimilar transition metal ions can lead to high level of charge transfer and induce substantial redistribution of electrons and ions. Notable examples include i) enhancing correlation effects and inducing a metal-insulator transition; ii) tailoring magnetic structures and inducing interfacial ferromagnetism; iii) engineering orbital splitting and inducing a non-cuprate single-orbital Fermi surface. Utilizing charge transfer to induce emergent electronic/magnetic/orbital properties at oxide interfaces is a robust approach. Combining charge transfer with quantum confinement and expitaxial strain provides an appealing prospect of engineering electronic structure of artificial oxide heterostructures. This research was supported by National Science Foundation under Grant No. DMR-1120296.

  18. Transfer functions

    Science.gov (United States)

    Taback, I.

    1979-01-01

    The vulnerability of electronic equipment to carbon fibers is studied. The effectiveness of interfaces, such as filters, doors, window screens, and cabinets, which affect the concentration, exposure, or deposition of carbon fibers on both (internal and external) sides of the interface is examined. The transfer function of multilayer aluminum mesh, wet and dry, polyurethane foam, and window screen are determined as a function of air velocity. FIlters installed in typical traffic control boxes and air conditioners are also considered.

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

    Science.gov (United States)

    Marr, G.

    2003-01-01

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

  20. ROGER a potential orbital space debris removal system

    Science.gov (United States)

    Starke, Juergen; Bischof, Bernd; Foth, W.-O.; -J., J.; Günther

    The previous activities in the field of On Orbit Servicing studied in the 1990's included in partic-ular the capability of vehicles in GEO to capture and support satellites (mainly communication satellites) to enable repair and continuation of operations, and finally the controlled transfer the target into a permanent graveyard orbit. The specific capture tools for these applications were mostly based on robotic systems to capture and fix the target under specific dynamic constraints (e.g. slowly tumbling target) without damage, and to allow the stabilization, re-orientation and potential repair of the target and subsequent release or transport to the final disposal orbit. Due to the drastically increasing number of debris particularly in the Low Earth Orbits (SSO) the active debris removal is now necessary to counteract to the predicted debris production cascade (Kessler Syndrome), which means the pollution of the total sphere in low earth orbit and not only the SSO area. In most of the debris congresses it was recommended to start removal with the still integrated systems as soon as possible. In the case of large debris objects, the soft capture system can be replaced by a simpler and robust system able to operate from a safe distance to the target and flexible enough to capture and hold different types of targets such as deactivated and/or defective satellites, upper stages and big fragments. These nominally non -cooperative targets might be partially destroyed by the capture process, but the production of additional debris shall be avoided. A major argument for the commercial applications is a multi-target mission potential, which is possible at GEO because the transfer propellant requirement to the disposal orbit and the return to the orbit of the next potential target is relative low (orbits with similar inclination and altitude). The proposed ROGER system is designed as a spacecraft with rendezvous capabilities including inspection in the vicinity of the

  1. Orbit graphs and face-transitivity of k-orbit polytopes

    OpenAIRE

    Cunningham, Gabe

    2012-01-01

    The orbit graph of a k-orbit polytope is a graph on k nodes that shows how the flag orbits are related by flag adjacency. Using orbit graphs, we classify k-orbit polytopes and determine when a k-orbit polytope is i-transitive. We then provide an explicit classification of three-orbit polytopes, and we describe a generating set for their automorphism groups.

  2. Tumor pathology of the orbit.

    Science.gov (United States)

    Héran, F; Bergès, O; Blustajn, J; Boucenna, M; Charbonneau, F; Koskas, P; Lafitte, F; Nau, E; Roux, P; Sadik, J C; Savatovsky, J; Williams, M

    2014-10-01

    The term orbital tumor covers a wide range of benign and malignant diseases affecting specific component of the orbit or developing in contact with them. They are found incidentally or may be investigated as part of the assessment of a systemic disorder or because of orbital signs (exophthalmos, pain, etc.). Computed tomography, MRI and Color Doppler Ultrasound (CDU), play a varying role depending on the clinical presentation and the disease being investigated. This article reflects long experience in a reference center but does not claim to be exhaustive. We have chosen to consider these tumors from the perspective of their usual presentation, emphasizing the most common causes and suggestive radiological and clinical presentations (progressive or sudden-onset exophthalmos, children or adults, lacrimal gland lesions, periorbital lesions and enophthalmos). We will describe in particular muscle involvement (thyrotoxicosis and tumors), vascular lesions (cavernous sinus hemangioma, orbital varix, cystic lymphangioma), childhood lesions and orbital hematomas. We offer straightforward useful protocols for simple investigation and differential diagnosis. Readers who wish to go further to extend their knowledge in this fascinating area can refer to the references in the bibliography.

  3. First Spacecraft Orbit of Mercury

    Science.gov (United States)

    Showstack, Randy

    2011-03-01

    After a 7.9-billion-kilometer flight since its launch on 3 August 2004—which included flybys of Earth, Venus, and Mercury—NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered a planned, highly elliptical orbit around the closest planet to our Sun on 17 March. Engineers in the mission operations center at the Johns Hopkins University Applied Physics Laboratory (JHU/APL) in Laurel, Md., which manages the mission for NASA, received radiometric signals indicating a successful orbit insertion at 9:10 P.M. local time. "Tonight we will have orbited the fifth planet in the solar system. This is a major accomplishment," Ed Weiler, NASA assistant administrator for the Science Mission Directorate, said at a 17 March public forum at JHU/APL, noting that spacecraft have previously entered orbit around several other planets. "You only go into orbit for the first time around Mercury once in human history, and that is what was accomplished tonight."

  4. Featured Image: Globular Cluster Orbits

    Science.gov (United States)

    Kohler, Susanna

    2017-04-01

    This figure (click for the full view) shows the meridional galactic orbits of 12 globular clusters that orbit the Milky Way. The recent release of stellar parallax data from Gaia allowed a team of scientists at Dartmouth College to improve measurements of a number of galactic globular clusters very old clusters of stars that can either orbit within the galactic disk and bulge or more distantly in the galactic halo. In a recent publication led by Erin OMalley, the team presents their findings and combines their new measurements for the clusters with proper motions from past studies to calculate the orbits that these globulars take. These calculations show us whether the clusters reside in the galactic disk and bulge (as only NGC 104 does in the sample shown here, since its orbit is confined to 8 kpc radially and 4 kpc vertically of the galactic center), or if they are halo clusters. To learn more about the authors work, you can check out the paper below!CitationErin M. OMalley et al 2017 ApJ 838 162. doi:10.3847/1538-4357/aa6574

  5. Quantum transport in ferromagnetic graphene super lattice in the presence of Rashba spin–orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Hasanirokh, Kobra; Esmaelpour, Mohammad; Mohammadpour, Hakimeh; Phirouznia, Arash

    2014-05-01

    Using the transfer matrix method, we study the electron transport through a single-layer graphene superlattice with alternating layers of ferromagnetic and normal regions with Rashba spin–orbit coupling. We show that the transport properties of the system depend strongly on the superlattice parameters. As another result, Rashba spin–orbit coupling manifests to be of crucial importance in controlling the transmission probabilities and Giant Magneto Resistance (GMR).

  6. The Eccentric Behavior of Nearly Frozen Orbits

    Science.gov (United States)

    Sweetser, Theodore H.; Vincent, Mark A.

    2013-01-01

    Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

  7. MRI of orbital hydroxyapatite implants

    Energy Technology Data Exchange (ETDEWEB)

    Flanders, A.E. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); De Potter, P. [Dept. of Ophthalmology, Wills Eye Inst., Philadelphia, PA (United States); Rao, V.M. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); Tom, B.M. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); Shields, C.L. [Dept. of Ophthalmology, Wills Eye Inst., Philadelphia, PA (United States); Shields, J.A. [Dept. of Ophthalmology, Wills Eye Inst., Philadelphia, PA (United States)

    1996-04-01

    Our aim was to use MRI for the postsurgical assessment of a new form of integrated orbital implant composed of a porous calcium phosphate hydroxyapatite substrate. We studied ten patients 24-74 years of age who underwent enucleation and implantation of a hydroxyapatite ball; 5-13 months after surgery, each patient was examined by spin-echo MRI, with fat suppression and gadolinium enhancement. Fibrovascular ingrowth was demonstrated in all ten patients as areas of enhancement at the periphery of the hydroxyapatite sphere that extended to the center to a variable degree. The radiologist should aware of the MRI appearances of the coralline hydroxyapatite orbital implant since it is now widely used following enucleation. MRI is a useful means to determine successful incorporation of the substrate into the orbital tissues. The normal pattern of contrast enhancement should not be mistaken for recurrent tumor or infection. (orig.)

  8. Orbital Evolution of 4179 Toutatis

    CERN Document Server

    Siregar, Suryadi

    2013-01-01

    Asteroid 1934 CT;1989 AC, well known as 4179 Toutatis, is an Apollo and Mars-crosser asteroid with a chaotic orbit produced by a 3:1 resonance with Jupiter and a 1:4 resonance with the Earth, and frequent close approaches to the Earth. It is listed as a potential hazardous object (PHA). The aim of this study is to investigate the possibility of 4179 Toutatis to be ejected from the Solar System. This paper presents an orbital evolution of 4179 Toutatis in time interval of ~300 kyr. Investigation of its orbital evolution is conducted by using the Mercury subroutine package, where the gravitational perturbations of eight major planets in the Solar System are considered. Over very short time scales (~300 kyr) relative to the Solar System life time (~10 Gyr), the asteroid 4179 Toutatis gave an example of chaotic motion that can cause asteroid to move outward and may be followed by escaping from the Solar System.

  9. Oncocytic Adenocarcinoma of the Orbit.

    Science.gov (United States)

    Harris, Gerald J; Paul, Sean; Hunt, Bryan C

    Oncocytic adenocarcinoma of the orbit is a rare tumor, with 1 case of nonlacrimal sac, nonlacrimal gland origin, and a poor outcome previously reported. An 85-year-old man with a 2-month history of left-sided epiphora, enlarging eyelid nodules, and diplopia in left gaze was found on imaging to have a poorly circumscribed, nodular mass of uniform radiodensity in the inferomedial orbit. Incisional biopsy revealed morphologic and immunohistochemical features of oncocytic adenocarcinoma with origin in the caruncle suspected, and CT of the neck, chest, abdomen, and pelvis showed no metastases or remote primary tumor source. Based on multidisciplinary consensus, orbital exenteration with adjuvant radiation therapy was performed, and there was no evidence of residual or recurrent tumor 2 years after treatment.

  10. Multiple Myeloma of the Orbit

    Directory of Open Access Journals (Sweden)

    Mona Hassan

    2012-01-01

    Full Text Available The authors report a case of a 62-year-old female with history of multiple myeloma who presents with complains of swelling and pain in her right eye. On examination, it was found that she has proptosis, chemosis, and diplopia along with decreased vision. Initial workup and treatment did not yield significant results, eventually she was found to have myelomatous changes in her right orbit on MRI and was diagnosed with multiple myeloma of the orbit which resolved solely with radiation. This case tends to highlight the importance of considering myeloma of the orbit as a very important and early differential diagnosis in a patient with a history of multiple myeloma presenting with a swollen and painful eye.

  11. GridOrbit public display

    DEFF Research Database (Denmark)

    Ramos, Juan David Hincapie; Tabard, Aurélien; Bardram, Jakob

    2010-01-01

    We introduce GridOrbit, a public awareness display that visualizes the activity of a community grid used in a biology laboratory. This community grid executes bioin-formatics algorithms and relies on users to donate CPU cycles to the grid. The goal of GridOrbit is to create a shared awareness about...... the research taking place in the biology laboratory. This should promote contribu-tions to the grid, and thereby mediate the appropriation of the grid technology. GridOrbit visualizes the activity in the grid, shows information about the different active projects, and supports a messaging functionality where...... people comment on projects. Our work explores the usage of interactive technologies as enablers for the appropriation of an otherwise invisible infrastructure....

  12. Orbital computed tomography for exophthalmos

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ok Keun; Lee, Hyun; Sol, Chang Hyo; Kim, Byung Soo [College of Medicine, Pusan National University, Busan (Korea, Republic of)

    1987-06-15

    Since exophthalmos is caused by any decrease in the size of bony orbit or occurrence of mass within the rigid orbit, the accurate diagnosis of its causes are essential in determining the therapeutic aims. Exophthalmos is one of the important signs being the indication for orbital computed tomography along with periorbital swelling, visual loss, orbital trauma and diplopia. CT as the diagnostic tool for the cause of exophthalmos not only displays a superb role with uncomparable quality in comparison to any conventional diagnostic methods but also has a decisive role in determining the therapeutic aims and the appropriate operative method when the operation is indicated. The orbital CT was performed from May in 1983 to May in 1985 whose with chief complaints were exophthalmos and 23 cases were confirmed by operation, biopsy, clinical progression or other diagnostic procedures. Here was report thoroughly analyzed 23 cases. The results were as follows : 1. The etiologic disease of exophthalmos were 6 cases of pseudotumor, 4 cases of thyroid ophthalmopathy, 4 cases of maxill ary sinus and nasal cavity Ca., 3 cases of mucocele and 1 case of alveolar soft part sarcoma, osteoma, dermoid cyst, pleomorphic adenoma, meningioma, and C.C.F. each. 2. The origin of the etiologic diseases of exophthalmos were 13 cases of primary within bony orbit and 10 cases of secondary from adjacent structure. 3. The site of lesions were 11 cases of intraconal and extraconal, 10 cases of extraconal, and 2 cases of intraconal origin. 4. The degree of exophthalmos in CT scan was in proportion to the volume of the mass except in the case of thyroid ophthalmopathy. The upper limit of normal range by CT scan using regression line equation was 16.2 mm in approximation. 5. CT was a very useful diagnostic tool in the accurate assessment of the kinds of lesion, its location, and its relationship to adjacent structures in the diagnosis of etiologic diseases of exophthalmos.

  13. A novel algorithm for generating libration point orbits about the collinear points

    Science.gov (United States)

    Ren, Yuan; Shan, Jinjun

    2014-09-01

    This paper presents a numerical algorithm that can generate long-term libration points orbits (LPOs) and the transfer orbits from the parking orbits to the LPOs in the circular-restricted three-body problem (CR3BP) and the full solar system model without initial guesses. The families of the quasi-periodic LPOs in the CR3BP can also be constructed with this algorithm. By using the dynamical behavior of LPO, the transfer orbit from the parking orbit to the LPO is generated using a bisection method. At the same time, a short segment of the target LPO connected with the transfer orbit is obtained, then the short segment of LPO is extended by correcting the state towards its adjacent point on the stable manifold of the target LPO with differential evolution algorithm. By implementing the correction strategy repeatedly, the LPOs can be extended to any length as needed. Moreover, combining with the continuation procedure, this algorithm can be used to generate the families of the quasi-periodic LPOs in the CR3BP.

  14. Heat transfer

    CERN Document Server

    Jorge, Kubie; Thomas, Grassie

    2012-01-01

    A core task of engineers is to analyse energy related problems. The analytical treatment is usually based on principles of thermodynamics, fluid mechanics and heat transfer, but is increasingly being handled computationally.This unique resource presents a practical textbook, written for both undergraduates and professionals, with a series of over 60 computer workbooks on an accompanying CD.The book emphasizes how complex problems can be deconstructed into a series of simple steps. All thermophysical property computations are illustrated using diagrams within text and on the compani

  15. moisture transfer

    Directory of Open Access Journals (Sweden)

    Don Kulasiri

    2005-01-01

    model drying porous materials. Coupled partial differential equations governing the moisture and heat transfer can be solved using numerical techniques, and in this paper we solve them analytically in a setting suitable for industrial drying situations. We discuss the nature of the solutions using the physical properties of Pinus radiata. It is shown that the temperature gradients play a significant role in deciding the moisture profiles within the material when thickness is large and that models based only on moisture potential gradients may not be sufficient to explain the drying phenomena in moist porous materials.

  16. Dawn Orbit Determination Team: Trajectory and Gravity Prediction Performance During Vesta Science Phases

    Science.gov (United States)

    Kennedy, Brian; Abrahamson, Matt; Ardito, Alessandro; Han, Dongsuk; Haw, Robert; Mastrodemos, Nicholas; Nandi, Sumita; Park, Ryan; Rush, Brian; Vaughan, Andrew

    2013-01-01

    The Dawn spacecraft was launched on September 27th, 2007. Its mission is to consecutively rendezvous with and observe the two largest bodies in the asteroid belt, Vesta and Ceres. It has already completed over a year's worth of direct observations of Vesta (spanning from early 2011 through late 2012) and is currently on a cruise trajectory to Ceres, where it will begin scientific observations in mid-2015. Achieving this data collection required careful planning and execution from all spacecraft teams. Dawn's Orbit Determination (OD) team was tasked with accurately predicting the trajectory of the Dawn spacecraft during the Vesta science phases, and also determining the parameters of Vesta to support future science orbit design. The future orbits included the upcoming science phase orbits as well as the transfer orbits between science phases. In all, five science phases were executed at Vesta, and this paper will describe some of the OD team contributions to the planning and execution of those phases.

  17. Dawn Orbit Determination Team: Trajectory and Gravity Prediction Performance During Vesta Science Phases

    Science.gov (United States)

    Kennedy, Brian; Abrahamson, Matt; Ardito, Alessandro; Han, Dongsuk; Haw, Robert; Mastrodemos, Nicholas; Nandi, Sumita; Park, Ryan; Rush, Brian; Vaughan, Andrew

    2013-01-01

    The Dawn spacecraft was launched on September 27th, 2007. Its mission is to consecutively rendezvous with and observe the two largest bodies in the asteroid belt, Vesta and Ceres. It has already completed over a year's worth of direct observations of Vesta (spanning from early 2011 through late 2012) and is currently on a cruise trajectory to Ceres, where it will begin scientific observations in mid-2015. Achieving this data collection required careful planning and execution from all spacecraft teams. Dawn's Orbit Determination (OD) team was tasked with accurately predicting the trajectory of the Dawn spacecraft during the Vesta science phases, and also determining the parameters of Vesta to support future science orbit design. The future orbits included the upcoming science phase orbits as well as the transfer orbits between science phases. In all, five science phases were executed at Vesta, and this paper will describe some of the OD team contributions to the planning and execution of those phases.

  18. 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.

  19. AA, closed orbit observation pickup

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    Electrostatic pickups around the circumference of the AA served for the measurement of the closed orbits across the wide momentum range of +- 3% to either side of central orbit. The pickups were of the "shoebox" type, with diagonal cuts, a horizontal and a vertical one mechanically coupled together. They were located where they would not require extra space. The wide ones (very wide indeed: 70 cm), like the one we see here, were placed inside the vacuum chamber of the wide quadrupoles QFW, at maximum dispersion. See also 8001372, 8001383, 8010045

  20. AA, closed orbit observation pickup

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    Electrostatic pickups around the circumference of the AA served for the measurement of the closed orbits across the wide momentum range of +- 3% to either side of central orbit. The pickups were of the "shoebox" type, with diagonal cuts, a horizontal and a vertical one mechanically coupled together. They were located where they would not require extra space. The wide ones (very wide indeed: 70 cm), like the one we see here, were placed inside the vacuum chamber of the wide quadrupoles, QFW, at maximum dispersion. See also 8001372,8001383, 8010042

  1. Orbital resonances around black holes.

    Science.gov (United States)

    Brink, Jeandrew; Geyer, Marisa; Hinderer, Tanja

    2015-02-27

    We compute the length and time scales associated with resonant orbits around Kerr black holes for all orbital and spin parameters. Resonance-induced effects are potentially observable when the Event Horizon Telescope resolves the inner structure of Sgr A*, when space-based gravitational wave detectors record phase shifts in the waveform during the resonant passage of a compact object spiraling into the black hole, or in the frequencies of quasiperiodic oscillations for accreting black holes. The onset of geodesic chaos for non-Kerr spacetimes should occur at the resonance locations quantified here.

  2. AA, closed orbit observation pickup

    CERN Multimedia

    1980-01-01

    Electrostatic pickups around the circumference of the AA served for the measurement of the closed orbits across the wide momentum range of +- 3% to either side of central orbit. The pickups were of the "shoebox" type, with diagonal cuts, a horizontal and a vertical one mechanically coupled together. They were located where they would not require extra space. The small ones, like the one we see here, were inserted into the vacuum chamber of the BLG (long and narrow) bending magnets. See also 8001372, 8010042, 8010045

  3. AA, closed orbit observation pickup

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    Electrostatic pickups around the circumference of the AA served for the measurement of the closed orbits across the wide momentum range of +- 3% to either side of central orbit. The pickups were of the "shoebox" type, with diagonal cuts, a horizontal and a vertical one mechanically coupled together. They were located where they would not require extra space. The small ones, like the one we see here, were inserted into the vacuum chamber of the BLG (long and narrow) bending magnets. Werner Sax contemplates his achievement. See also 8001383, 8010042, 8010045.

  4. Primary orbital squamous cell carcinoma

    Directory of Open Access Journals (Sweden)

    Ana L. Campos Arbulú

    2017-02-01

    Full Text Available Primary orbital squamous cell carcinoma is a rare entity. There is little published literature. We report a case of primary squamous cell carcinoma of the orbital soft tissues. Surgical resection offered the best treatment for the patient. Complete resection of the lesion was achieved. The patient received adjuvant radiotherapy due to the proximity of the lesion to the surgical margins. Surgical treatment is feasible and should be considered as part of the surgeon's arsenal. However, therapeutic decisions must be made on a case-by-case basis

  5. Nodular Fasciitis of the Orbit.

    Science.gov (United States)

    Compton, Christopher J; Clark, Jeremy D; Thompson, Matthew P; Lee, Hui Bae H; Nunery, William R

    A 13-month-old boy was presented with new onset proptosis of the right eye. CT scan and MRI showed an enhancing mass in the right superior orbit with local bone remodeling and erosion. A craniotomy was performed for biopsy and sub-total resection. Histopathology and immunohistochemistry confirmed the lesion to be nodular fasciitis. Nodular fasciitis lesions are classically found in the anterior ocular adnexa, especially in pediatric patients. This is the first reported case of nodular fasciitis arising in the posterior orbit of a child younger than 16.

  6. Spin torque on the surface of graphene in the presence of spin orbit splitting

    Directory of Open Access Journals (Sweden)

    Ji Chen

    2013-06-01

    Full Text Available We study theoretically the spin transfer torque of a ferromagnetic layer coupled to (deposited onto a graphene surface in the presence of the Rashba spin orbit coupling (RSOC. We show that the RSOC induces an effective magnetic field, which will result in the spin precession of conduction electrons. We derive correspondingly the generalized Landau-Lifshitz-Gilbert (LLG equation, which describes the precessional motion of local magnetization under the influence of the spin orbit effect. Our theoretical estimate indicates that the spin orbit spin torque may have significant effect on the magnetization dynamics of the ferromagnetic layer coupled to the graphene surface.

  7. On non-coplanar Hohmann Transfer using angles as parameters

    CERN Document Server

    Rincon, Angel; Lacruz, Elvis; Abellan, Gabriel; Diaz, Sttiwuer

    2015-01-01

    We study a more complex case of Hohmann orbital transfer of a satellite by considering non-coplanar and elliptical orbits, instead of planar and circular orbits. We use as parameter the angle between the initial and transference planes that minimizes the energy, and therefore the fuel of a satellite, through the application of two non-tangential impulses for all possible cases. We found an analytical expression that minimizes the energy for each configuration. Some reasonable physical constraints are used: we apply impulses at perigee or apogee of the orbit, we consider the duration of the impulse to be short compared to the duration of the trip, we take the nodal line of three orbits to be coincident and the three semimajor axes to lie in the same plane. We study the only four possible cases but assuming non-coplanar elliptic orbits. In addition, we validate our method through a numerical solution obtained by using some of the actual orbital elements of Sputnik I and Vanguard I satellites. For these orbits, ...

  8. Trajectory Design From GTO To Lunar Equatorial Orbit For The Dark Ages Radio Explorer (DARE) Spacecraft

    CERN Document Server

    Genova, Anthony L; Perez, Andres Dono; Galal, Ken F; Faber, Nicolas T; Mitchell, Scott; Landin, Brett; Datta, Abhirup; Burns, Jack O

    2015-01-01

    The trajectory design for the Dark Ages Radio Explorer (DARE) mission con-cept involves launching the DARE spacecraft into a geosynchronous transfer orbit (GTO) as a secondary payload. From GTO, the spacecraft then transfers to a lunar orbit that is stable (i.e., no station-keeping maneuvers are required with minimum perilune altitude always above 40 km) and allows for more than 1,000 cumulative hours for science measurements in the radio-quiet region located on the lunar farside.

  9. Zygomatico-orbital artery as a recipient vessel for microsurgical head and neck reconstruction.

    Science.gov (United States)

    Higashino, Takuya; Sawamoto, Naoya; Hirai, Rintaro; Arikawa, Masaki

    2013-07-01

    The selection of recipient vessels in head and neck reconstruction is one of the key factors influencing its difficulty and outcome. We report a case of a microsurgical scalp reconstruction using the zygomatico-orbital artery as a recipient vessel.A 71-year-old woman had intractable skin ulcers on her head after neurosurgeries. Computed tomography angiography findings showed that the superficial temporal artery was obstructed and that the zygomatico-orbital artery ran forward and upward. She underwent scalp reconstruction using a free anterior lateral thigh flap. The zygomatico-orbital artery was dissected distally, cut, and turned over cranially. The diameter of the zygomatico-orbital artery was 1.2 mm. The blood flow through the zygomatico-orbital artery was sufficient. The thinned scalp area was excised, and some of the titanium devices and infectious tissues were removed. An anterior lateral thigh flap measuring 20 × 9 cm was harvested and transferred to the defect in the head. The discrepancy in calibers was within double, and the zygomatico-orbital artery fit the descending branch of the lateral circumflex femoral artery. The flap was transferred successfully.The zygomatico-orbital artery is one of the branches from the external carotid artery and supports the suprazygomatic territory. The zygomatico-orbital artery is present in 78% to 92% of people and originates from the superficial temporal artery and sometimes from the frontal branch of superficial temporal artery. The mean diameter of the zygomatico-orbital artery at origin is reported to be 1.20 mm. The zygomatico-orbital artery is another option as a recipient vessel in head and neck reconstruction.

  10. Orbit/CLASP is required for myosin accumulation at the cleavage furrow in Drosophila male meiosis.

    Directory of Open Access Journals (Sweden)

    Daishi Kitazawa

    Full Text Available Peripheral microtubules (MTs near the cell cortex are essential for the positioning and continuous constriction of the contractile ring (CR in cytokinesis. Time-lapse observations of Drosophila male meiosis showed that myosin II was first recruited along the cell cortex independent of MTs. Then, shortly after peripheral MTs made contact with the equatorial cortex, myosin II was concentrated there in a narrow band. After MT contact, anillin and F-actin abruptly appeared on the equatorial cortex, simultaneously with myosin accumulation. We found that the accumulation of myosin did not require centralspindlin, but was instead dependent on Orbit, a Drosophila ortholog of the MT plus-end tracking protein CLASP. This protein is required for stabilization of central spindle MTs, which are essential for cytokinesis. Orbit was also localized in a mid-zone of peripheral MTs, and was concentrated in a ring at the equatorial cortex during late anaphase. Fluorescence resonance energy transfer experiments indicated that Orbit is closely associated with F-actin in the CR. We also showed that the myosin heavy chain was in close proximity with Orbit in the cleavage furrow region. Centralspindlin was dispensable in Orbit ring formation. Instead, the Polo-KLP3A/Feo complex was required for the Orbit accumulation independently of the Orbit MT-binding domain. However, orbit mutations of consensus sites for the phosphorylation of Cdk1 or Polo did not influence the Orbit accumulation, suggesting an indirect regulatory role of these protein kinases in Orbit localization. Orbit was also necessary for the maintenance of the CR. Our data suggest that Orbit plays an essential role as a connector between MTs and the CR in Drosophila male meiosis.

  11. Precision Orbit Determination for the Lunar Reconnaissance Orbiter: orbit quality and gravity field estimation

    Science.gov (United States)

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

    2010-12-01

    We present results of the Precision Orbit Determination work undertaken by the Lunar Orbiter Laser Altimeter (LOLA) Science Team for the Lunar Reconnaissance Orbiter (LRO) mission, in order to meet the position knowledge accuracy requirements (50-m total position) and to precisely geolocate the LRO datasets. In addition to the radiometric tracking data, one-way laser ranges (LR) between Earth stations and the spacecraft are made possible by a small telescope mounted on the spacecraft high-gain antenna. The photons received from Earth are transmitted to one LOLA detector by a fiber optics bundle. The LOLA timing system enables 5-s LR normal points with precision better than 10cm. Other types of geodetic constraints are derived from the altimetric data itself. The orbit geometry can be constrained at the times of laser groundtrack intersections (crossovers). Due to the Moon's slow rotation, orbit solutions and normal equations including altimeter crossovers are processed and created in one month batches. Recent high-resolution topographic maps near the lunar poles are used to produce a new kind of geodetic constraints. Purely geometric, those do not necessitate actual groundtrack intersections. We assess the contributions of those data types, and the quality of our orbits. Solutions which use altimetric crossover meet the horizontal 50-m requirement, and perform usually better (10-20m). We also obtain gravity field solutions based on LRO and historical data. The various LRO data are accumulated into normal equations, separately for each one month batch and for each measurement type, which enables the final weights to be adjusted during the least-squares inversion step. Expansion coefficients to degree and order 150 are estimated, and a Kaula rule is still needed to stabilize the farside field. The gravity field solutions are compared to previous solutions (GLGM-3, LP150Q, SGM100h) and the geopotential predicted from the latest LOLA spherical harmonic expansion.

  12. Astrometric positioning and orbit determination of geostationary satellites

    Science.gov (United States)

    Montojo, F. J.; López Moratalla, T.; Abad, C.

    2011-03-01

    In the project titled “Astrometric Positioning of Geostationary Satellite” (PASAGE), carried out by the Real Instituto y Observatorio de la Armada (ROA), optical observation techniques were developed to allow satellites to be located in the geostationary ring with angular accuracies of up to a few tenths of an arcsec. These techniques do not necessarily require the use of large telescopes or especially dark areas, and furthermore, because optical observation is a passive method, they could be directly applicable to the detection and monitoring of passive objects such as space debris in the geostationary ring.By using single-station angular observations, geostationary satellite orbits with positional uncertainties below 350 m (2 sigma) were reconstructed using the Orbit Determination Tool Kit software, by Analytical Graphics, Inc. This software is used in collaboration with the Spanish Instituto Nacional de Técnica Aeroespacial.Orbit determination can be improved by taking into consideration the data from other stations, such as angular observations alone or together with ranging measurements to the satellite. Tests were carried out combining angular observations with the ranging measurements obtained from the Two-Way Satellite Time and Frequency Transfer technique that is used by ROA’s Time Section to carry out time transfer with other laboratories. Results show a reduction of the 2 sigma uncertainty to less than 100 m.

  13. An Earth Orbiting Satellite Service and Repair Facility

    Science.gov (United States)

    Berndt, Andrew; Cardoza, Mike; Chen, John; Daley, Gunter; Frizzell, Andy; Linton, Richard; Rast, Wayne

    1989-01-01

    A conceptual design was produced for the Geosynchronous Satellite Servicing Platform (GSSP), an orbital facility capable of repairing and servicing satellites in geosynchronous orbit. The GSSP is a man-tended platform, which consists of a habitation module, operations module, service bay and truss assembly. This design review includes an analysis of life support systems, thermal and power requirements, robotic and automated systems, control methods and navigation, and communications systems. The GSSP will utilize existing technology available at the time of construction, focusing mainly on modifying and integrating existing systems. The entire facility, along with two satellite retrieval vehicles (SRV), will be placed in geosynchronous orbit by the Advanced Launch System. The SRV will be used to ferry satellites to and from the GSSP. Technicians will be transferred from Earth to the GSSP and back in an Apollo-derived Crew Transfer Capsule (CTC). These missions will use advanced telerobotic equipment to inspect and service satellites. Four of these missions are tentatively scheduled per year. At this rate, the GSSP will service over 650 satelites during the projected 25 year lifespan.

  14. Optimal Reorientation Of Spacecraft Orbit

    Directory of Open Access Journals (Sweden)

    Chelnokov Yuriy Nikolaevich

    2014-06-01

    Full Text Available The problem of optimal reorientation of the spacecraft orbit is considered. For solving the problem we used quaternion equations of motion written in rotating coordinate system. The use of quaternion variables makes this consideration more efficient. The problem of optimal control is solved on the basis of the maximum principle. An example of numerical solution of the problem is given.

  15. DOT strategies versus orbiter strategies

    NARCIS (Netherlands)

    Rutten, R.J.

    2001-01-01

    The Dutch Open Telescope is a high-resolution solar imager coming on-line at La Palma. The definition of the DOT science niche, strategies, and requirements resemble Solar Orbiter considerations and deliberations. I discuss the latter in the light of the former, and claim that multi-line observation

  16. Three planets orbiting Wolf 1061

    CERN Document Server

    Wright, D J; Tinney, C G; Bentley, J S; Zhao, Jinglin

    2015-01-01

    We use archival HARPS spectra to detect three planets orbiting the M3 dwarf Wolf1061 (GJ 628). We detect a 1.36 Mearth minimum-mass planet with an orbital period P = 4.888d (Wolf1061b), a 4.25 Mearth minimum-mass planet with orbital period P = 17.867d (Wolf1061c), and a likely 5.21 Mearth minimum-mass planet with orbital period P = 67.274d (Wolf1061d). All of the planets are of sufficiently low mass that they may be rocky in nature. The 17.867d planet falls within the habitable zone for Wolf 1061 and the 67.274d planet falls just outside the outer boundary of the habitable zone. There are no signs of activity observed in the bisector spans, cross-correlation full-width-half-maxima, Calcium H & K indices, NaD indices, or H-alpha indices near the planetary periods. We use custom methods to generate a cross-correlation template tailored to the star. The resulting velocities do not suffer the strong annual variation observed in the HARPS DRS velocities. This differential technique should deliver better exploi...

  17. Orbital abscess: Management and outcome

    Directory of Open Access Journals (Sweden)

    N Suneetha

    2000-01-01

    Full Text Available Purpose: To discuss the diagnosis, management and outcome of various types of orbital abscess. Methods: The medical records of 13 patients diagnosed and treated for orbital abscess were reviewed. The sources of infection included: paranasal sinusitis (n = 5, odontogenic origin of infection (n = 4, one each, temporal fossa abscess, palatal abscess, furuncle on the nose, and secondary to retrobulbar injection of steroid. Computed tomographic scans revealed the presence of an abscess in all 13 cases. Associated findings on CT scan included: sinus disease (n = 8, cavernous sinus thrombosis (n = 2 and subdural empyema (n = 2. All patients were treated with intensive, multiple, intravenous antibiotics and early surgical drainage. Results: Purulent material collected surgically from the orbit cultured Staphylococcus aureus (n = 3, two each Pseudomonas aeruginosa, Proteus mirabilis, Acinetobacter species and one each β-haemolytic Streptococci, Citrobacter frundi and Enterobacter. Final visual acuity was good in 6 patients (6/12 - 6/6 and no light perception in 6 others. Visual acuity could not be recorded in the infant. The other complications were intracranial abscess (n = 4, cavernous sinus thrombosis (n = 2 and restricted ocular motility (n = 1. Conclusions: A high index of suspicion is necessary, along with early institution of appropriate diagnostic imaging, and aggressive medical and surgical treatment for a favourable outcome in cases of orbital abscess.

  18. Myeloid Sarcoma in the Orbit.

    Science.gov (United States)

    Qian, Xiaoxiao; Gigantelli, James W; Abromowitch, Minnie; Morgan, Linda A; Suh, Donny W

    2016-12-08

    The authors describe a case of myeloid sarcoma of the orbit in a pediatric patient. An 8-month-old male infant presented to the ophthalmology clinic with a left orbital mass, which had been increasing in size over the previous 2 months. The mass was initially diagnosed at another clinic as an infantile hemangioma, and had been treated with a topical formulation of timolol. In the ophthalmology clinic, orbital magnetic resonance imaging showed a solid enhancing mass. A biopsy was performed, and histopathology revealed myeloid sarcoma. The disease responded well to a standard chemotherapy regimen. Myeloid sarcoma is a rare, extra-medullary presentation that can occur as an isolated tumor, concurrently with or at relapse of acute myeloid leukemia. Because few cases of myeloid sarcoma in the orbit have been reported, this case report aids in the management of myeloid sarcoma in pediatric patients. The report describes an 8-month-old male infant, the youngest patient to develop myeloid sarcoma without preexisting acute myeloid leukemia. [J Pediatr Ophthalmol Strabismus. 2016;53:e64-e68.].

  19. 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…

  20. Energy and the Elliptical Orbit

    Science.gov (United States)

    Nettles, Bill

    2009-01-01

    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…

  1. Removing Orbital Debris with Lasers

    CERN Document Server

    Phipps, Claude R; Bradford, Brian; George, E Victor; Libby, Stephen B; Liedahl, Duane A; Marcovici, Bogdan; Olivier, Scot S; Pleasance, Lyn D; Reilly, James P; Rubenchik, Alexander; Strafford, David N; Valley, Michael T

    2011-01-01

    Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of LEO space is threatened by runaway collisional cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1 cm demands serious attention. A promising proposed solution uses a high power pulsed laser system on the Earth to make plasma jets on the objects, slowing them slightly, and causing them to re-enter and burn up in the atmosphere. In this paper, we reassess this approach in light of recent advances in low-cost, light-weight modular design for large mirrors, calculations of laser-induced orbit changes and in design of repetitive, multi-kilojoule lasers, that build on inertial fusion research. These advances now suggest that laser orbital debris removal (LODR) is the most cost-effective way to mitigate the debris problem. No other solutions have been proposed that address the whole problem of large and small debris. A LODR system will have multiple uses beyond debris removal. Internat...

  2. THREE PLANETS ORBITING WOLF 1061

    Energy Technology Data Exchange (ETDEWEB)

    Wright, D. J.; Wittenmyer, R. A.; Tinney, C. G.; Bentley, J. S.; Zhao, Jinglin, E-mail: duncan.wright@unsw.edu.au [Department of Astronomy and Australian Centre for Astrobiology, School of Physics, University of New South Wales, NSW 2052 (Australia)

    2016-02-01

    We use archival HARPS spectra to detect three planets orbiting the M3 dwarf Wolf 1061 (GJ 628). We detect a 1.36 M{sub ⊕} minimum-mass planet with an orbital period P = 4.888 days (Wolf 1061b), a 4.25 M{sub ⊕} minimum-mass planet with orbital period P = 17.867 days (Wolf 1061c), and a likely 5.21 M{sub ⊕} minimum-mass planet with orbital period P = 67.274 days (Wolf 1061d). All of the planets are of sufficiently low mass that they may be rocky in nature. The 17.867 day planet falls within the habitable zone for Wolf 1061 and the 67.274 day planet falls just outside the outer boundary of the habitable zone. There are no signs of activity observed in the bisector spans, cross-correlation FWHMs, calcium H and K indices, NaD indices, or Hα indices near the planetary periods. We use custom methods to generate a cross-correlation template tailored to the star. The resulting velocities do not suffer the strong annual variation observed in the HARPS DRS velocities. This differential technique should deliver better exploitation of the archival HARPS data for the detection of planets at extremely low amplitudes.

  3. NATO: In-orbit experience

    Science.gov (United States)

    Capulli, J. J.

    1980-01-01

    The performance of the NATO-111-A and NATO 111-B satellite battery is reported. The electrical power subsystem is briefly described. The electrical characteristics and the reconditioning experience of the batteries is cited. The in-orbit experience is compared with results of preflight accelerated life tests.

  4. Starshade Orbital Maneuver Study for WFIRST

    Science.gov (United States)

    Soto, Gabriel; Savransky, Dmitry; Garrett, Daniel; Delacroix, Christian; Sinha, Amlan

    2017-01-01

    The Wide Field Infrared Survey Telescope (WFIRST) mission, scheduled for launch in the mid-2020s will perform exoplanet science via both microlensing surveys and direct imaging. Currently, an internal coronagraph is planned to perform starlight suppression for exoplanet imaging. Alternatively, an external starshade could be used to achieve the required high contrasts. A starshade could potentially have higher throughput than an equivalent coronagraph, would also have the benefit of a wavelength-independent inner working angle (IWA), and would remove the requirement of deformable mirrors in the telescope optics. The starshade approach would require a separately-launched occulter spacecraft to be positioned at exact distances from the telescope along the line of sight to a target star system. We perform a detailed study to quantify the Δv requirements and feasibility of deploying this additional spacecraft as a means of exoplanet imaging. The fuel use of the occulter can be categorized into two phases: station-keeping during imaging and repositioning between different targets. WFIRST is assumed to be in a halo orbit about the Sun-Earth L2 point with an out of plane amplitude of 250,000km. Based on its designed IWA, the occulter is given an offset distance from the nominal WFIRST orbit. Target star systems and look vectors are generated using Exoplanet Open-Source Imaging Simulator (EXOSIMS); a boundary value problem is then solved between successive targets. Given a list of possible targets, the minimum time and minimum Δv transfers are computed. These methods are used to estimate the number of possible observations that could be performed with the expected available fuel mass limit imposed by the likely occulter launch vehicle.

  5. Exploring A Thermal-Orbital Feedback Mechanism At Europa

    Science.gov (United States)

    Walker, Matthew; Mitchell, Jonathan L.; Bills, Bruce

    2016-10-01

    We present a geophysical model of the Europa system to describe it's structural, orbital, and thermal states. In doing so, we examine the potential for feedback mechanisms to occur which can produce oscillatory behavior in shell thickness, eccentricity, and heat flux, due to the coupled nature of the relevant processes. We implement a tidal heating model to describe the heat flux into the body. This model depends primarily on the shell structure as well as the orbital eccentricity. The model has the capacity to consider multilayered bodies for which the interior structure can evolve over time. Furthermore, the tidal heating model is fully three dimensionally resolved, having the ability to predict radial and lateral variations in heating throughout Europa. This allows us to predict particular locations on Europa that should have the maximum surface heat flux. This heating model is coupled to the orbital evolution as well. Tidal dissipation pulls energy out of the orbit, effectively reducing the semi-major axis and eccentricity, circularizing the orbit. This would slow, and even shut down, the tidal heating at Europa, however, the Galilean Satellites' Laplace resonance continuously transfers energy back into Europa's orbit, keeping the tidal dissipation active. We compare the tidal heat input to the heat conducted out of the ice shell, which is a function of shell thickness, among other things. Heat transfer into or out of the ice compensates any imbalance of heat. This heating, in turn, leads to structural variations of the shell. For example, if tidal heating is greater than the heat conducted out of the shell, the remaining balance goes into sensible and latent heats which thin the shell (thus increasing the surface heat output to balance that which is tidally input). Oppositely, when conducted heat output is greater than the tidal heating, the shell thickens. Shell thickness variations then result in global extension or contraction, due to the density difference

  6. Shadowing Lemma and Chaotic Orbit Determination

    CERN Document Server

    Spoto, Federica

    2015-01-01

    Orbit determination is possible for a chaotic orbit of a dynamical system, given a finite set of observations, provided the initial conditions are at the central time. In a simple discrete model, the standard map, we tackle the problem of chaotic orbit determination when observations extend beyond the predictability horizon. If the orbit is hyperbolic, a shadowing orbit is computed by the least squares orbit determination. We test both the convergence of the orbit determination iterative procedure and the behaviour of the uncertainties as a function of the maximum number $n$ of map iterations observed. When the initial conditions belong to a chaotic orbit, the orbit determination is made impossible by numerical instability beyond a computability horizon, which can be approximately predicted by a simple formula. Moreover, the uncertainty of the results is sharply increased if a dynamical parameter is added to the initial conditions as parameter to be estimated. The uncertainty of the dynamical parameter decrea...

  7. The globe and orbit in Laron syndrome.

    Science.gov (United States)

    Kornreich, L; Konen, O; Lilos, P; Laron, Z

    2011-09-01

    Patients with LS have an inborn growth hormone resistance, resulting in failure to generate IGF-1. The purpose of this study was to evaluate the size of the eye and orbit in LS. We retrospectively reviewed the MR imaging of the brain in 9 patients with LS for the following parameters: axial diameter of the globe, interzygomatic distance, perpendicular distance from the interzygomatic line to margins of the globe, medial-to-lateral diameter of the orbit at the anterior orbital rim, distance from the anterior orbital rim to the anterior globe, maximal distance between the medial walls of the orbits, lateral orbital wall angle, lateral orbital wall length, and mediolateral thickness of the intraorbital fat in the most cranial image of the orbit. All measurements were made bilaterally. Twenty patients referred for MR imaging for unrelated reasons served as control subjects. Compared with the control group, the patients with LS had a significantly smaller maximal globe diameter and shallower but wider orbits due to a shorter lateral wall, a smaller medial distance between the orbits, and a larger angle of the orbit. The ratio between the most anterior orbital diameter and the globe was greater than that in controls. The position of the globe was more anterior in relation to the interzygomatic line. Shallow and wide orbits and small globes relative to orbital size are seen in LS and may be secondary to IGF-1 deficiency.

  8. Space shuttle orbiter trimmed center-of-gravity extension study. Volume 3: Impact of retrofits for center-of-gravity extension on orbiter thermal-protection system

    Science.gov (United States)

    Dunavant, J. C.

    1979-01-01

    Heat transfer studies were conducted at Mach 10.3 on space shuttle orbiter models with the S-2 fillet and C-4 canard retrofit moldlines which were generated in aerodynamic and system design studies to increase the allowable c.g. range of the orbiter. Areas of orbiter most strongly affected were the sides where a shear layer which separated along the wing leading edge impinged. Analytical studies of the heating effect on the thermal-protection system were made which indicated that scar weight on the orbiter sides due to allowances for retrofits of the S-2 fillet and C-4 canard is small (less than about 90 kg (200 lbs) in comparison to the total weight of the retrofit).

  9. [Orbital mycetoma: a case report].

    Science.gov (United States)

    Gueye, N N; Seck, S M; Diop, Y; Ndiaye Sow, M N; Agboton, G; Diakhaté, M; Dieng, M; Dieng, M T

    2013-05-01

    Mycetomas are pathological processes through which exogenous fungal or actinomycotic etiological agents produce grains. These etiological agents live in the soil and plants of endemic areas. They are introduced traumatically, primarily into the foot. The orbital location is rare. We report the case of a 17-year-old student admitted for progressive left proptosis over 2 years, following penetrating trauma by a fork in a rural setting. Examination revealed a heterogenous orbital mass with multiple fistulae, producing pus and black grains, and suggested, due to the color of the grains, a diagnosis of fungal mycetoma. MRI revealed a destructive process at the level of the lamina papracea of the ethmoid and the orbital floor. Anatomopathological examination confirmed the fungal nature of the infection, while culture in Sabouraud's medium was inconclusive. The outcome was favorable after exenteration and debridementof the ipsilateral maxillary sinus and nasal cavities, along with 4 months of ketoconazole. No recurrence has been observed for 14 months after surgery. Mycetomas are endemic to northwest Africa. Most frequently located in the foot, they are seldom seen in the orbit. The color of the grains provides a clue as to the etiology. Black-grain mycetomas are always fungal and are treated surgically--essentially like cancer--as the persistence of a single grain will cause a recurrence. The orbital location of a mycetoma is rare. In the present case report, the concept of port of entry, the clinical appearance, and the color of the grains guided the diagnosis. The histological examination of the surgical specimen confirmed the diagnosis. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  10. Space Shuttle Orbiter-Illustration

    Science.gov (United States)

    2001-01-01

    This illustration is an orbiter cutaway view with callouts. The orbiter is both the brains and heart of the Space Transportation System (STS). About the same size and weight as a DC-9 aircraft, the orbiter contains the pressurized crew compartment (which can normally carry up to seven crew members), the huge cargo bay, and the three main engines mounted on its aft end. There are three levels to the crew cabin. Uppermost is the flight deck where the commander and the pilot control the mission. The middeck is where the gallery, toilet, sleep stations, and storage and experiment lockers are found for the basic needs of weightless daily living. Also located in the middeck is the airlock hatch into the cargo bay and space beyond. It is through this hatch and airlock that astronauts go to don their spacesuits and marned maneuvering units in preparation for extravehicular activities, more popularly known as spacewalks. The Space Shuttle's cargo bay is adaptable to hundreds of tasks. Large enough to accommodate a tour bus (60 x 15 feet or 18.3 x 4.6 meters), the cargo bay carries satellites, spacecraft, and spacelab scientific laboratories to and from Earth orbit. It is also a work station for astronauts to repair satellites, a foundation from which to erect space structures, and a hold for retrieved satellites to be returned to Earth. Thermal tile insulation and blankets (also known as the thermal protection system or TPS) cover the underbelly, bottom of the wings, and other heat-bearing surfaces of the orbiter to protect it during its fiery reentry into the Earth's atmosphere. The Shuttle's 24,000 individual tiles are made primarily of pure-sand silicate fibers, mixed with a ceramic binder. The solid rocket boosters (SRB's) are designed as an in-house Marshall Space Flight Center project, with United Space Boosters as the assembly and refurbishment contractor. The solid rocket motor (SRM) is provided by the Morton Thiokol Corporation.

  11. Polarization control of single photon quantum orbital angular momentum states.

    Science.gov (United States)

    Nagali, E; Sciarrino, F; De Martini, F; Piccirillo, B; Karimi, E; Marrucci, L; Santamato, E

    2009-10-12

    The orbital angular momentum of photons, being defined in an infinite-dimensional discrete Hilbert space, offers a promising resource for high-dimensional quantum information protocols in quantum optics. The biggest obstacle to its wider use is presently represented by the limited set of tools available for its control and manipulation. Here, we introduce and test experimentally a series of simple optical schemes for the coherent transfer of quantum information from the polarization to the orbital angular momentum of single photons and vice versa. All our schemes exploit a newly developed optical device, the so-called "q-plate", which enables the manipulation of the photon orbital angular momentum driven by the polarization degree of freedom. By stacking several q-plates in a suitable sequence, one can also have access to higher-order angular momentum subspaces. In particular, we demonstrate the control of the orbital angular momentum m degree of freedom within the subspaces of |m| = 2h and |m| = 4h per photon.

  12. Orbital excitation blockade and algorithmic cooling in quantum gases.

    Science.gov (United States)

    Bakr, Waseem S; Preiss, Philipp M; Tai, M Eric; Ma, Ruichao; Simon, Jonathan; Greiner, Markus

    2011-12-21

    Interaction blockade occurs when strong interactions in a confined, few-body system prevent a particle from occupying an otherwise accessible quantum state. Blockade phenomena reveal the underlying granular nature of quantum systems and allow for the detection and manipulation of the constituent particles, be they electrons, spins, atoms or photons. Applications include single-electron transistors based on electronic Coulomb blockade and quantum logic gates in Rydberg atoms. Here we report a form of interaction blockade that occurs when transferring ultracold atoms between orbitals in an optical lattice. We call this orbital excitation blockade (OEB). In this system, atoms at the same lattice site undergo coherent collisions described by a contact interaction whose strength depends strongly on the orbital wavefunctions of the atoms. We induce coherent orbital excitations by modulating the lattice depth, and observe staircase-like excitation behaviour as we cross the interaction-split resonances by tuning the modulation frequency. As an application of OEB, we demonstrate algorithmic cooling of quantum gases: a sequence of reversible OEB-based quantum operations isolates the entropy in one part of the system and then an irreversible step removes the entropy from the gas. This technique may make it possible to cool quantum gases to have the ultralow entropies required for quantum simulation of strongly correlated electron systems. In addition, the close analogy between OEB and dipole blockade in Rydberg atoms provides a plan for the implementation of two-quantum-bit gates in a quantum computing architecture with natural scalability.

  13. Mixed fleet assessment for on-orbit consumables resupply

    Science.gov (United States)

    Eberhardt, Ralph N.; Dominick, Sam M.

    1988-01-01

    Significant increases in the cost effectiveness and operational flexibility of in-space systems can be realized when the capability to replenish consumable fluids and propellants is incorporated into the designs of spacecraft, satellites, and orbiting platforms and laboratories. Reusable tankers are currently being designed for transporting fluids to space. A number of options exist for transporting the fluids and propellants to the space-based user systems. The fluids can be transported to space either in the Shuttle cargo bay or using Expendable Launch Vehicles (ELVs). Resupply can thus be accomplished either from the Shuttle bay, or the tanker can be removed from an ELV and attached to a carrier such as the Orbital Maneuvering Vehicle (OMV) or Orbital Transfer Vehicle (OTV) for transport to the user to be serviced. A third option involves locating the tanker at the Space Station or an unmanned platform as a quasi-permanent servicing facility which returns to the ground for recycling once its tanks have been depleted. This paper documents the impacts of a mixed fleet approach to consumables logistics to orbit. Both storable fluids and propellants, and superfluid helium, are considered. Current modular tanker designs for monopropellants, bipropellants and water for Space Station propulsion are discussed. Trade-offs in superfluid helium tanker sizes, shapes to fit the range of ELVs currently available, and boil-off losses associated with longer-term (greater than 6 months) space-basing, are addressed.

  14. Study on the construction of satisfactory nonorthogonal localized molecular orbitals

    Institute of Scientific and Technical Information of China (English)

    FENG; Huasheng; BIAN; Jiang; LI; Lemin

    2004-01-01

    Comparing to orthogonal localized molecular orbitals (OLMO), the nonorthogonal localized molecular orbitals (NOLMO) exhibit bonding pictures more accordant with those in the traditional chemistry. They are more contracted, so that they have a better transferability and better performances for the calculation of election correlation energies and for the linear scaling algorithms of large systems. The satisfactory NOLMOs should be as contracted as possible while their shapes and spatial distribution keep in accordance with the traditional chemical bonding picture. It is found that the spread of NOLMOs is a monotonic decreasing function of their orthogonality, and it may reduce to any extent as the orthogonality descends. However, when the orthogonality descends to some point, the shapes and spatial distribution of the NOLMOs deviate drastically from the traditional chemical bonding picture, and finally the NOLMOs tend to linear dependence. Without the requirement of orthogonalization, some other constraints have to be imposed for constructing satisfactory NOLMOs by minimizing their spread functional. It is shown that satisfactory results can be generated by coupling the minimization of orbital spread functionals with the maximization of the distances between orbital centroids.

  15. Autonomous robotic operations for on-orbit satellite servicing

    Science.gov (United States)

    Ogilvie, Andrew; Allport, Justin; Hannah, Michael; Lymer, John

    2008-04-01

    The Orbital Express Demonstration System (OEDS) flight test successfully demonstrated technologies required to autonomously service satellites on-orbit. The mission's integrated robotics solution, the Orbital Express Demonstration Manipulator System (OEDMS) developed by MDA, performed critical flight test operations. The OEDMS comprised a six-jointed robotic manipulator arm and its avionics, non-proprietary servicing and ORU (Orbital Replacement Unit) interfaces, a vision and arm control system for autonomous satellite capture, and a suite of Ground Segment and Flight Segment software allowing script generation and execution under supervised or full autonomy. The arm was mounted on ASTRO, the servicer spacecraft developed by Boeing. The NextSat, developed by Ball Aerospace, served as the client satellite. The OEDMS demonstrated two key goals of the OEDS flight test: autonomous free-flyer capture and berthing of a client satellite, and autonomous transfer of ORUs from servicer to client and back. The paper provides a description of the OEDMS and the key operations it performed.

  16. Low Thrust Cis-Lunar Transfers Using a 40 kW-Class Solar Electric Propulsion Spacecraft

    Science.gov (United States)

    Mcguire, Melissa L.; Burke, Laura M.; Mccarty, Steven L.; Hack, Kurt J.; Whitley, Ryan J.; Davis, Diane C.; Ocampo, Cesar

    2017-01-01

    This paper captures trajectory analysis of a representative low thrust, high power Solar Electric Propulsion (SEP) vehicle to move a mass around cis-lunar space in the range of 20 to 40 kW power to the Electric Propulsion (EP) system. These cis-lunar transfers depart from a selected Near Rectilinear Halo Orbit (NRHO) and target other cis-lunar orbits. The NRHO cannot be characterized in the classical two-body dynamics more familiar in the human spaceflight community, and the use of low thrust orbit transfers provides unique analysis challenges. Among the target orbit destinations documented in this paper are transfers between a Southern and Northern NRHO, transfers between the NRHO and a Distant Retrograde Orbit (DRO) and a transfer between the NRHO and two different Earth Moon Lagrange Point 2 (EML2) Halo orbits. Because many different NRHOs and EML2 halo orbits exist, simplifying assumptions rely on previous analysis of orbits that meet current abort and communication requirements for human mission planning. Investigation is done into the sensitivities of these low thrust transfers to EP system power. Additionally, the impact of the Thrust to Weight ratio of these low thrust SEP systems and the ability to transit between these unique orbits are investigated.

  17. A New Tour Design Technique to Enable an Enceladus Orbiter

    Science.gov (United States)

    Strange, N.; Campagnola, S.; Russell, R.

    2009-12-01

    As a result of discoveries made by the Cassini spacecraft, Saturn's moon Enceladus has emerged as a high science-value target for a future orbiter mission. [1] However, past studies of an Enceladus orbiter mission [2] found that entering Enceladus orbit either requires a prohibitively large orbit insertion ΔV (> 3.5 km/s) or a prohibitively long flight time. In order to reach Enceladus with a reasonable flight time and ΔV budget, a new tour design method has been developed that uses gravity-assists of the low-mass moons Rhea, Dione, and Tethys combined with v-infinity leveraging maneuvers. This new method can achieve Enceladus orbit with a combined leveraging and insertion ΔV of ~1 km/s and a 2.5 year Saturn tour. Among many challenges in designing a trajectory for an Enceladus mission, the two most prominent arise because Enceladus is a low mass moon (its GM is only ~7 km^2/s^2), deep within Saturn's gravity well (its orbit is at 4 Saturn radii). Designing ΔV-efficient rendezvous with Enceladus is the first challenge, while the second involves finding a stable orbit which can achieve the desired science measurements. A paper by Russell and Lara [3] has recently addressed the second problem, and a paper this past August by Strange, Campagnola, and Russell [4] has adressed the first. This method developed to solve the second problem, the leveraging tour, and the science possibilities of this trajectory will be the subject of this presentation. the new methods in [4], a leveraging tour with Titan, Rhea, Dione, and Tethys can reach Enceladus orbit with less than half of the ΔV of a direct Titan-Enceladus transfer. Starting from the TSSM Saturn arrival conditions [5], with a chemical bi-prop system, this new tour design technique could place into Enceladus orbit ~2800 kg compared to ~1100 kg from a direct Titan-Enceladus transfer. Moreover, the 2.5 year leveraging tour provides many low-speed and high science value flybys of Rhea, Dione, and Tethys. This exciting

  18. 'Orbital volume restoration rate after orbital fracture'; a CT-based orbital volume measurement for evaluation of orbital wall reconstructive effect.

    Science.gov (United States)

    Wi, J M; Sung, K H; Chi, M

    2017-01-13

    PurposeTo evaluate the effect of orbital reconstruction and factors related to the effect of orbital reconstruction by assessing of orbital volume using orbital computed tomography (CT) in cases of orbital wall fracture.MethodsIn this retrospective study, 68 patients with isolated blowout fractures were evaluated. The volumes of orbits and herniated orbital tissues were determined by CT scans using a three-dimensional reconstruction technique (the Eclipse Treatment Planning System). Orbital CT was performed preoperatively, immediately after surgery, and at final follow ups (minimum of 6 months). We evaluated the reconstructive effect of surgery making a new formula, 'orbital volume reconstruction rate' from orbital volume differences between fractured and contralateral orbits before surgery, immediately after surgery, and at final follow up.ResultsMean volume of fractured orbits before surgery was 23.01±2.60 cm(3) and that of contralateral orbits was 21.31±2.50 cm(3) (P=0.005). Mean volume of the fractured orbits immediately after surgery was 21.29±2.42 cm(3), and that of the contralateral orbits was 21.33±2.52 cm(3) (P=0.921). Mean volume of fractured orbits at final follow up was 21.50±2.44 cm(3), and that of contralateral orbits was 21.32±2.50 cm(3) (P=0.668). The mean orbital volume reconstruction rate was 100.47% immediately after surgery and 99.17% at final follow up. No significant difference in orbital volume reconstruction rate was observed with respect to fracture site or orbital implant type. Patients that underwent operation within 14 days of trauma had a better reconstruction rate at final follow up than patients who underwent operation over 14 days after trauma (P=0.039).ConclusionComputer-based measurements of orbital fracture volume can be used to evaluate the reconstructive effect of orbital implants and provide useful quantitative information. Significant reduction of orbital volume is observed immediately after orbital wall

  19. In-Flight Operation of the Dawn Ion Propulsion System Through Orbit Capture at Vesta

    Science.gov (United States)

    Garner, Charles E.; Rayman, Marc D.; Brophy, John R.; Mikes, Steven C.

    2011-01-01

    The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from 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 into an Earth-escape trajectory. Onboard the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide most of the ?V needed for heliocentric transfer to Vesta, orbit capture at Vesta, transfer among Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer among Ceres science orbits. The first 80 days after launch were dedicated to the initial checkout of the spacecraft which was followed by about ten months of full-power thrusting leading to a Mars gravity assist in February 2009 that provided 1 km/s of heliocentric energy increase and is the only part of the mission following launch in which a needed velocity change is not accomplished by the IPS. Deterministic thrusting for heliocentric transfer to Vesta resumed in June 2009 and was concluded with orbit capture at Vesta in July 2011. IPS was operated for approximately 23,400 hours, consumed approximately 250 kg of xenon, and provided a delta-V of approximately 6.7 km/s to achieve orbit capture at Vesta. IPS performance characteristics are very close to the expected performance characteristics based on analysis performed pre-launch. The only significant problem to have occurred over the almost four years of IPS operations in flight was the temporary failure of a valve driver board in DCIU-1, resulting in a loss of thrust of approximately 29 hours. Thrusting operations resumed after switching to DCIU-2, and power cycling conducted after orbit capture indicates DCIU-1 is completely operational. After about three weeks of survey operations IPS will be used to maneuver the

  20. [Rhino-orbital mucormycosis with orbital abscess: a case report].

    Science.gov (United States)

    Tatar, Emel Cadallı; Sürenoğlu, Unzile Akpınar; Işık, Eray; Tütüncü, Ediz; Korkmaz, Hakan

    2011-01-01

    Sinonasal mucormycosis is a rare, life-threatening and insidious fungal infection. Uncontrolled diabetes mellitus and immunsupression are the most important risk factors. The infection is clinically characterized by black necrotic tissues and crusting in the nasal cavity. In acute fulminant rhinosinusitis and particularly in infections caused by mucor species, black scar tissues seen on the nasal mucosa are pathognomonic. High level of suspicion in the risk group the diagnosis is confirmed by histopathological examination. The rhinoorbital form is even rarer and the findings may range from orbital pain to ophtalmoplegia and blindness. In this report we present a 72-year-old female patient with uncontrolled type 2 diabetes mellitus who was admited with the complaints of exophtalmos in the left eye, diplopia and headache. In the physical examination there was purulent discharge in the middle meatus and left orbital abscess was detected on computed tomography. We performed an emergency endoscopic sinus surgery. While we did not observe any necrotic tissues, granulation tissues were detected and pus was drained from the orbital cavity. The result of the histopathological examination was reported as invasive mucormycosis. We presented this case to emphasize the importance of early diagnosis and treatment of rhinoorbital mucormycosis.

  1. Dynamics of weak stability boundary transfer trajectories to Moon

    Science.gov (United States)

    Dutt, Pooja; Anilkumar, A. K.; George, R. K.

    2016-11-01

    In order to design a WSB trajectory to Moon, highly elliptical geocentric orbit is propagated forward in time so that its perigee increases to Earth-Moon distance. Another highly elliptical selenocentric orbit is propagated backward in time till it starts moving towards Earth. The two trajectories are patched using Fixed Time of Arrival targeting method to obtain a WSB transfer trajectory. In this paper, various geocentric and selenocentric orbits are considered and eligible candidates for WSB transfer are represented on the phase space with color code on transfer time. Genetic Algorithm is used to find patching points to reduce the sum of Δ V required at the patching points. Lunar fly-by on the way to apogee is also studied.

  2. Targeting Low-Energy Ballistic Lunar Transfers

    Science.gov (United States)

    Parker, Jeffrey S.

    2010-01-01

    Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

  3. Aiming at a 1-cm orbit for low earth orbiters: Reduced-dynamic and kinematic precise orbit determination

    NARCIS (Netherlands)

    Visser, P.N.A.M.; Van den IJssel, J.

    2003-01-01

    The computation of high-accuracy orbits is a prerequisite for the success of Low Earth Orbiter (LEO) missions such as CHAMP, GRACE and GOCE. The mission objectives of these satellites cannot be reached without computing orbits with an accuracy at the few cm level. Such a level of accuracy might be a

  4. 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.

  5. Overview of the Mars Reconnaissance Orbiter mission

    Science.gov (United States)

    Mateer, B.; Graf, J.; Zurek, R.; Jones, R.; Eisen, H.; Johnston, M.; Jai, D. B.

    2002-01-01

    The Mars Reconnaissance Orbiter will deliver to Mars orbit a payload to conduct remote sensing science observations, characterize sites for future landers, and provide critical telecom/navigation relay capability for follow-on missions.

  6. Tumors of the orbit; Orbitatumoren

    Energy Technology Data Exchange (ETDEWEB)

    Mueller-Forell, Wibke [Klinikum der Univ. Mainz (Germany). Inst. fuer Neuroradiologie

    2008-09-15

    This short review will present an overview not only of the findings in imaging, but the main clinical symptoms of the different orbital space occupying lesions, (not only different tumors, but even tumor-like lesions), as those should be included in differential diagnostic consideration. This should lead to a targeted diagnostic procedure in the individual patient. Basic knowledge of orbital anatomy is as important as the knowledge of the pros and contra's of computed tomography (CT) and magnetic resonance imaging (MRI), which should influence the examination protocol. Imaging findings of the most important tumors/lesions of the globe, the intraconal and extraconal space as well as of the optic nerve are presented with different examples (without any demand of completeness). (orig.)

  7. Canadian Meteor Orbit Radar (CMOR

    Directory of Open Access Journals (Sweden)

    A. R. Webster

    2004-01-01

    Full Text Available The radar system described here (CMOR comprises a basic 5-element receiving system, co-located with a pulsed transmitter, specifically designed to observe meteor echoes and to determine their position in space with an angular resolution of ~1° and a radial resolution of ~3 km. Two secondary receiving sites, a few km distant and arranged to form approximately a right angle with the base station, allow the determination of the velocity (speed and direction of the meteor that, together with the time of occurrence, lead to an estimate of the orbit of the original meteoroid. Some equipment details are presented along with a method used to determine the orbits. Representative echoes are shown and observations on the 2002 Leonid shower presented.

  8. SILEX in-orbit performances

    Science.gov (United States)

    Planche, Gilles; Chorvalli, Vincent

    2004-06-01

    PASTEL embarked on-board SPOT4, French LEO earth observation satellite, and OPALE mounted on-board ARTEMIS, European GEO telecommunication satellite are the key components of SILEX (Semi-conductor Inter-satellite Link Experiment) system. Launched in March 1998, PASTEL terminal was first verified via star tracking. Then, first SILEX optical communication was successfully performed in December 2001 with ARTEMIS at 31000 km. Following 12 months ARTEMIS orbit rising, SILEX commissioning phase was successfully achieved in spring 2003. Today, more than hundred successful optical communications have been achieved. On 1st of October 2003, the SILEX optical link was declared fully operational by the European and French space agencies. After a recall of SILEX architecture, design and on-ground verification, this paper reports on in-orbit results.

  9. The rehybridization of electronic orbitals in carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ouyang Yu; Peng Jing-Cui; Wang Hui; Peng Zhi-Hua

    2008-01-01

    Rehybridization of electronic orbitals in carbon nanotubes contains tilting angles of π orbital, electrons wavefunc-tions of π orbital and σ orbital, degrees of hybridization, etc. In this paper, we have obtained analytical formulas of tilting angle of π orbital relative to tube surface, electrons wavefunctions of π orbital and σ orbital, degrees of hybridization, separately, as well as the numerical results.

  10. Anteromedial Approach to the Orbit

    OpenAIRE

    DEDA, Haluk; Ugur, Hasan Çaglar; Yorulmaz, Irfan; Kucuk, Babur

    2001-01-01

    This study evaluated the surgical results of the anteromedial approach for treatment of orbital lesions in 16 patients. Pre- and postoperatively, all patients underwent a complete physical examination focusing on the head and neck area including a thorough ophthalmologic evaluation, computerized tomography, and magnetic resonance imaging. The surgical approach was limited to a medial orbitotomy in five patients; the remaining 11 patients underwent a medial orbitotomy combined with an external...

  11. A new kinematical definition of orbital eccentricity

    Directory of Open Access Journals (Sweden)

    Ninković S.

    2009-01-01

    Full Text Available A new concept of orbital eccentricity is given. The dimensionless quantities proposed in the present paper to serve as orbital eccentricities have a kinematical nature. The purpose is to use them in describing the motion for the case of three-dimensional orbits. A comparison done for nearly planar orbits shows that the values of the eccentricities proposed here do not differ significantly from those corresponding to the eccentricities of geometric nature usually applied.

  12. Understanding pediatric bacterial preseptal and orbital cellulitis

    Directory of Open Access Journals (Sweden)

    Gonzalez Mithra

    2010-01-01

    Full Text Available Pediatric preseptal and orbital cellulitis are infectious disorders that result in periorbital inflammation. Preseptal cellulitis is often associated with breaches in the skin barrier whereas orbital cellulitis is commonly associated with paranasal sinusitis. Orbital cellulitis may be associated with subperiosteal abscess. It is important to distinguish between preseptal from orbital cellulitis. Clinical examination and diagnostic imaging are useful in determining appropriate management. Patients are usually treated with broad spectrum antibiotics and surgery when indicated.

  13. Spin-orbit ferromagnetic resonance

    Science.gov (United States)

    Ferguson, Andrew

    2013-03-01

    In conventional magnetic resonance techniques the magnitude and direction of the oscillatory magnetic field are (at least approximately) known. This oscillatory field is used to probe the properties of a spin ensemble. Here, I will describe experiments that do the inverse. I will discuss how we use a magnetic resonance technique to map out the current-induced effective magnetic fields in the ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P). These current-induced fields have their origin in the spin-orbit interaction. Effective magnetic fields are observed with symmetries which resemble the Dresselhaus and Rashba spin-orbit interactions and which depend on the diagonal and off-diagonal strain respectively. Ferromagnetic semiconductor materials of different strains, annealing conditions and concentrations are studied and the results compared with theoretical calculations. Our original study measured the rectification voltage coming from the product of the oscillatory magnetoresistance, during magnetisation precession, and the alternating current. More recently we have developed an impedance matching technique which enables us to extract microwave voltages from these high resistance (10 k Ω) samples. In this way we measure the microwave voltage coming from the product of the oscillating magneto-resistance and a direct current. The direct current is observed to affect the magnetisation precession, indicating that anti-damping as well as field-like torques can originate from the spin-orbit interaction.

  14. Proxima's orbit around Alpha Centauri

    CERN Document Server

    Kervella, P

    2016-01-01

    Proxima and Alpha Centauri AB have almost identical distances and proper motions with respect to the Sun. Although the probability of such similar parameters is in principle very low, the question whether they actually form a single gravitationally bound triple system has been open since the discovery of Proxima one century ago. Owing to recent high precision radial velocity measurements and the revision of the parameters of the Alpha Cen pair, we show that Proxima and Alpha Cen are gravitationally bound with a high degree of confidence. The orbital period of Proxima is approximately 600 000 years, with a moderate excentricity of 0.42 +0.07 -0.08. Proxima comes within 5.3 -0.9 +1.2 kAU of Alpha Cen at periastron, and the apastron occurs at 12.9 +0.3 -0.1 kAU. This orbital motion may have influenced the formation or evolution of the recently discovered planet orbiting Proxima as well as circumbinary planet formation around Alpha Cen.

  15. Access to Mars from Earth-Moon Libration Point Orbits:. [Manifold and Direct Options

    Science.gov (United States)

    Kakoi, Masaki; Howell, Kathleen C.; Folta, David

    2014-01-01

    This investigation is focused specifically on transfers from Earth-Moon L(sub 1)/L(sub 2) libration point orbits to Mars. Initially, the analysis is based in the circular restricted three-body problem to utilize the framework of the invariant manifolds. Various departure scenarios are compared, including arcs that leverage manifolds associated with the Sun-Earth L(sub 2) orbits as well as non-manifold trajectories. For the manifold options, ballistic transfers from Earth-Moon L(sub 2) libration point orbits to Sun-Earth L(sub 1)/L(sub 2) halo orbits are first computed. This autonomous procedure applies to both departure and arrival between the Earth-Moon and Sun-Earth systems. Departure times in the lunar cycle, amplitudes and types of libration point orbits, manifold selection, and the orientation/location of the surface of section all contribute to produce a variety of options. As the destination planet, the ephemeris position for Mars is employed throughout the analysis. The complete transfer is transitioned to the ephemeris model after the initial design phase. Results for multiple departure/arrival scenarios are compared.

  16. The puzzling orbital period evolution of the LMXB AX J1745.6-2901

    Science.gov (United States)

    Ponti, G.; De, K.; Muñoz-Darias, T.; Stella, L.; Nandra, K.

    2016-09-01

    The orbital period evolution of X-ray binaries provides fundamental clues to understanding mechanisms of angular momentum transfer and loss in these systems. We present an X-ray eclipse timing analysis of the transient low mass X-ray binary AX J1745.6-2901. This system shows full eclipses and thus is one of the few objects of this class for which accurate orbital evolution studies can be carried out. We report on XMM-Newton and ASCA observations covering 30 complete X-ray eclipses spanning an interval of more than 20 years. We improve the determination of the orbital period to a relative precision of 2 × 10-8, two orders of magnitudes better than previous measurements. We determine, for the first time, a highly significant rate of decrease of the orbital period dot{P}_{orb}=-4.03± 0.32× 10^{-11} s/s. This is at least one order of magnitude larger than expected from conservative mass transfer and angular momentum losses due to gravitational waves and magnetic braking, and might result from either non-conservative mass transfer or magnetic activity changing the quadrupole moment of the companion star. Imprinted on the long term evolution of the orbit, we observe highly significant eclipse leads-delays of ˜10 - 30 s, characterised by a clear state dependence in which, on average, eclipses occur earlier during the hard state.

  17. The puzzling orbital period evolution of the LMXB AX J1745.6-2901

    Science.gov (United States)

    Ponti, G.; De, K.; Muñoz-Darias, T.; Stella, L.; Nandra, K.

    2017-01-01

    The orbital period evolution of X-ray binaries provides fundamental clues to understanding mechanisms of angular momentum transfer and loss in these systems. We present an X-ray eclipse timing analysis of the transient low-mass X-ray binary AX J1745.6-2901. This system shows full eclipses and thus is one of the few objects of this class for which accurate orbital evolution studies can be carried out. We report on XMM-Newton and ASCA observations covering 30 complete X-ray eclipses spanning an interval of more than 20 yr. We improve the determination of the orbital period to a relative precision of 2 × 10-8, two orders of magnitudes better than previous measurements. We determine, for the first time, a highly significant rate of decrease of the orbital period dot{P}_{orb}=-4.03± 0.32{×} 10^{-11} s s-1. This is at least one order of magnitude larger than expected from conservative mass transfer and angular momentum losses due to gravitational waves and magnetic braking, and might result from either non-conservative mass transfer or magnetic activity changing the quadrupole moment of the companion star. Imprinted on the long-term evolution of the orbit, we observe highly significant eclipse leads-delays of ˜10-30 s, characterized by a clear state dependence in which, on average, eclipses occur earlier during the hard state.

  18. Servicing of multiple satellites using an OMV-derived transfer vehicle

    Science.gov (United States)

    Graves, Carl D.; Meissinger, Hans F.; Rosen, Alan

    Servicing vehicles and supplies to be used for extending the mission life of polar orbiting satellites will be launched into orbit by expendable launch vehicles, since the Space Shuttle currently is not expected to operate in this orbital regime. The Orbital Maneuvering Vehicle or a smaller version being designed for this purpose, and its performance potential as a permanently space-based satellite servicing vehicle, are the subject of this paper. A single servicing vehicle of this class can maneuver, as required, to visit multiple user satellites in their respective orbits. Cost-effective orbit transfer techniques are essential for a viable multi-satellite servicing scenario. Such transfer modes and servicing scenarios, and the usable payload delivery performance achievable are analyzed and compared.

  19. The LHC Orbit and Trajectory System

    CERN Document Server

    Bishop, D; Calvo-Giraldo, E; Cocq, D; Jensen, L; Jones, R; Savioz, J J; Waters, G

    2003-01-01

    This paper describes the definitive acquisition system selected for the measurement of the closed orbit and trajectory in the CERN-LHC and its transfer lines. The system is based on a Wide Band Time Normaliser (WBTN) followed by a 10-bit ADC and a Digital Acquisition Board (DAB), the latter developed by TRIUMF, Canada. The complete chain works at 40MHz, so allowing the position of each bunch to be measured individually. In order to avoid radiation problems with the electronics in the LHC tunnel, all the digital systems will be kept on the surface and linked to the analogue front-ends via a single mode fibre-optic connection. Slow control via a WorldFIP fieldbus will be used in the tunnel for setting the various operational modes of the system and will also be used to check power supply statuses. As well as describing the hardware involved, some results will be shown from a complete prototype system installed on four pick-ups in the CERN-SPS using the full LHC topology.

  20. Spin orbit torque based electronic neuron

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Abhronil, E-mail: asengup@purdue.edu; Choday, Sri Harsha; Kim, Yusung; Roy, Kaushik [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2015-04-06

    A device based on current-induced spin-orbit torque (SOT) that functions as an electronic neuron is proposed in this work. The SOT device implements an artificial neuron's thresholding (transfer) function. In the first step of a two-step switching scheme, a charge current places the magnetization of a nano-magnet along the hard-axis, i.e., an unstable point for the magnet. In the second step, the SOT device (neuron) receives a current (from the synapses) which moves the magnetization from the unstable point to one of the two stable states. The polarity of the synaptic current encodes the excitatory and inhibitory nature of the neuron input and determines the final orientation of the magnetization. A resistive crossbar array, functioning as synapses, generates a bipolar current that is a weighted sum of the inputs. The simulation of a two layer feed-forward artificial neural network based on the SOT electronic neuron shows that it consumes ∼3× lower power than a 45 nm digital CMOS implementation, while reaching ∼80% accuracy in the classification of 100 images of handwritten digits from the MNIST dataset.

  1. Optical communications beyond orbital angular momentum

    Science.gov (United States)

    Rosales-Guzmán, Carmelo; Trichili, Abderrahmen; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

    2016-09-01

    Current optical communication technologies are predicted to face a bandwidth capacity limit in the near future. The nature of the limitation is fundamental rather than technological and is set by nonlinearities in optical fibers. One solution, suggested over 30 years ago, comprises the use of spatial modes of light as information carriers. Along this direction, light beams endowed with orbital angular momentum (OAM) have been demonstrated as potential information carriers in both, free space and fibres. However, recent studies suggest that purely OAM modes does not increase the bandwidth of optical communication systems. In fact, in all work to date, only the azimuthal component of transverse spatial modes has been used. Crucially, all transverse spatial modes require two degrees of freedom to be described; in the context of Laguerre-Gaussian (LGp`) beams these are azimuthal (l) and radial (p), the former responsible for OAM. Here, we demonstrate a technique where both degrees of freedom of LG modes are used as information carrier over free space. We transfer images encoded using 100 spatial modes in three wavelengths as our basis, and employ a spatial demultiplexing scheme that detects all 100 modes simultaneously. Our scheme is a hybrid of MIMO and SMM, and serves as a proof-of-principle demonstration. The cross-talk between the modes is small and independent of whether OAM modes are used or not.

  2. The geostationary orbit and developing countries

    Science.gov (United States)

    Medina, E. R.

    1982-01-01

    The geostationary orbit is becoming congested due to use by several countries throughout the world, and the request for use of this orbit is increasing. There are 188 geostationary stations in operation. An equitable distribution of stations on this orbit is requested.

  3. Information Measures for Statistical Orbit Determination

    Science.gov (United States)

    Mashiku, Alinda K.

    2013-01-01

    The current Situational Space Awareness (SSA) is faced with a huge task of tracking the increasing number of space objects. The tracking of space objects requires frequent and accurate monitoring for orbit maintenance and collision avoidance using methods for statistical orbit determination. Statistical orbit determination enables us to obtain…

  4. The History of the Molniya Orbit

    Science.gov (United States)

    Kettering Group

    Arthur C. Clarke's name is often linked with the Geostationary orbit as a result of his 1945 paper in Wireless World. Less well-known is where the credit for discovering the Molniya orbit should lie. This paper presents the evidence uncovered to date concerning the original concept and provides some insight into the ways in which the orbit has subsequently been exploited.

  5. Atomic Orbitals for the New Millennium

    CERN Document Server

    Williams, J M

    1999-01-01

    This very short article introduces a set of nested atomic orbitals, called MCAS, to replace the current s, p, d, and f orbitals. The simplest orbital is a tetrahedrally directed, four lobed, mono-orbital instead of the spherical s orbital. All the other orbitals, no matter what their energy (shell) level is, are nested with this one. All the electrons have the same spin and only one electron is allotted to each orbital. Electron spin pairing is accomplished through opposing orbitals instead of actual electron spin reversal. Orbital energy level is maintained by nuclear propulsion through perigee kick. Orbitals hybridize as Aufbau proceeds, in contrast to the inflexible, current building model. The inert gases have completely uniform electronic shells that contain only one orbital type per shell. Since outer completed shells have only one type of orbital, all eight outer electrons are identical rather than being of two types as occurs in the current model; hence, Lewis' electron-dot octet. Hydrogen should resi...

  6. Orbital Topology Controlling Charge Injection in Quantum-Dot-Sensitized Solar Cells.

    Science.gov (United States)

    Hansen, Thorsten; Žídek, Karel; Zheng, Kaibo; Abdellah, Mohamed; Chábera, Pavel; Persson, Petter; Pullerits, Tõnu

    2014-04-03

    Quantum-dot-sensitized solar cells are emerging as a promising development of dye-sensitized solar cells, where photostable semiconductor quantum dots replace molecular dyes. Upon photoexcitation of a quantum dot, an electron is transferred to a high-band-gap metal oxide. Swift electron transfer is crucial to ensure a high overall efficiency of the solar cell. Using femtosecond time-resolved spectroscopy, we find the rate of electron transfer to be surprisingly sensitive to the chemical structure of the linker molecules that attach the quantum dots to the metal oxide. A rectangular barrier model is unable to capture the observed variation. Applying bridge-mediated electron-transfer theory, we find that the electron-transfer rates depend on the topology of the frontier orbital of the molecular linker. This promises the capability of fine tuning the electron-transfer rates by rational design of the linker molecules.

  7. 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

  8. Orbital-Dependent Density Functionals for Chemical Catalysis

    Science.gov (United States)

    2011-02-16

    Biradical ...transferred  state  is  a   biradical .  The   lowest-­‐energy  adiabatic  singlet  state  shows  at  least  two  minima  along... biradical )  at  intermediate  approach  (Ca⋯C  distance  ≈2.5–2.7   Å)  with  molecular  orbital  structure  ϕ1ϕ2,

  9. Orbital forcing of the Paleocene and Eocene carbon cycle

    Science.gov (United States)

    Zeebe, Richard E.; Westerhold, Thomas; Littler, Kate; Zachos, James C.

    2017-05-01

    Multimillion-year proxy records across the Paleocene and Eocene show prominent variations on orbital time scales. The cycles, which have been identified at various sites across the globe, preferentially concentrate spectral power at eccentricity and precessional frequencies. It is evident that these cycles are an expression of changes in global climate and carbon cycling paced by astronomical forcing. However, little is currently known about the link between orbital forcing and the carbon cycle-climate system and the amplitude of associated atmospheric CO2 variations. Here we use simple and complex carbon cycle models to explore the basic effect of different orbital forcing schemes and noise on the carbon cycle. Our primary modeling target is the high-resolution, ˜7.7 Myr long, benthic isotope record at Ocean Drilling Program Site 1262 in the South Atlantic. For direct insolation forcing (as opposed to artificial eccentricity-tilt-precession), one major challenge is understanding how the system transfers spectral power from high to low frequencies. We discuss feasible solutions, including insolation transformations analogous to electronic AC-DC conversion (DC'ing). Regarding mechanisms, we focus on tropical insolation and a long-term carbon imbalance in terrestrial organic burial/oxidation but do not rule out other scenarios. Our analysis shows that high-latitude mechanisms are unlikely drivers of orbitally paced changes in the late Paleocene-early Eocene (LPEE) Earth system. Furthermore, we provide constraints on the origin and isotopic composition of a possible LPEE cyclic carbon imbalance/source responding to astronomical forcing. Our simulations also reveal a mechanism for the large δ13C-eccentricity lag at the 400 kyr period observed in Paleocene, Oligocene, and Miocene sections. We present the first estimates of orbital-scale variations in atmospheric CO2 during the late Paleocene and early Eocene.

  10. Neutron orbital radii in {sup 13} C; Radios orbitales neutronicos en {sup 13} C

    Energy Technology Data Exchange (ETDEWEB)

    Aguilera R, E.F.; Murillo, G.; Ramirez, J.J.; Avila, O.L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1988-01-15

    In this work its were carried out experimental measurements of the reaction {sup 12}C(d,p) {sup 13}C at low energy. Preliminary results of a DWBA analysis of the data are presented, and the possibility of using this reaction to obtain the orbital radius of the transferred neutron is investigated. (Author)

  11. Propagation of orbital angular momentum carrying beams through a perturbing medium

    CSIR Research Space (South Africa)

    Chaibi, A

    2013-09-01

    Full Text Available The orbital angular momentum of light has been suggested as a means of information transfer over free-space, yet the detected optical vortex is known to be sensitive to perturbation. Such effects have been studied theoretically, in particular...

  12. Charge-Transfer Matrix Elements by FMO-LCMO Approach: Hole Transfer in DNA with Parameter Tuned Range-Separated DFT

    CERN Document Server

    Kitoh-Nishioka, Hirotaka

    2016-01-01

    A scheme for computing charge-transfer matrix elements with the linear combination of fragment molecular orbitals and the 'nonempirically tuned range-separated' density functional is presented. It takes account of the self-consistent orbital relaxation induced by environmental Coulomb field and the exchange interaction in fragment pairs at low computational scaling along the system size. The accuracy was confirmed numerically on benchmark systems of imidazole and furane homo-dimer cations. Applications to hole transfers in DNA nucleobase pairs and in a $\\pi$-stack adenine octomer highlight the effects of orbital relaxation.

  13. Orbital, subconjunctival, and subcutaneous emphysema after an orbital floor fracture

    OpenAIRE

    2013-01-01

    Osama H Ababneh Department of Ophthalmology, The University of Jordan and Jordan University Hospital, Amman, Jordan Abstract: A 16-year-old boy presented to the emergency department with the complaint of a sudden, painful left eye and proptosis after an episode of sneezing. A few hours earlier, he had sustained a blunt trauma to the left orbit as the result of a fistfight. The initial examination showed subcutaneous and subconjunctival emphysema. Visual acuity in the left eye was 20/30 (0.67...

  14. A Survey of Research on Service-Spacecraft Orbit Design

    Institute of Scientific and Technical Information of China (English)

    LI Yue; ZHANG Jian-xin; ZHANG Qiang; WEI Xiao-peng

    2013-01-01

    On-orbit service spacecraft orbit problem has been addressed for decades. The research of on-orbit service spacecraft orbit can be roughly divided into orbit design and orbit optimization. The paper mainly focuses on the orbit design problem. We simply summarize of the previous works, and point out the main content of the on-orbit service spacecraft orbit design. We classify current on-orbit service spacecraft orbit design problem into parking-orbit design, maneuvering-orbit design and servicing-orbit design. Then, we give a detail description of the three specific orbits, and put forward our own ideas on the existed achievements. The paper will provide a meaningful reference for the on-orbit service spacecraft orbital design research.

  15. New Orbit Propagator to Be Used in Orbital Debris Evolutionary Models

    OpenAIRE

    Narumi, Tomohiro; Hanada, Toshiya

    2007-01-01

    An orbital environment debris evolutionary model for low Earth orbit has been developed at Kyushu University. A fast orbit propagator is essentially needed in such an evolutionary model because the number of space debris larger than 1 cm in low earth orbit is very large and it takes much time to compute long-term orbital changes of space debris. The effects of orbital perturbations are investigated for hundreds of years, and the rate of change in orbital elements were invented by earlier publ...

  16. Space Shuttle Orbiter auxiliary power unit status

    Science.gov (United States)

    Reck, M.; Loken, G.; Horton, J.; Lukens, W.; Scott, W.; Baughman, J.; Bauch, T.

    An overview of the United States Space Shuttle Orbiter APU, which provides power to the Orbiter vehicle hydraulic system, is presented. Three complete APU systems, each with its own separate fuel system, supply power to three dedicated hydraulic systems. These in turn provide power to all Orbiter vehicle critical flight functions including launch, orbit, reentry, and landing. The basic APU logic diagram is presented. The APU includes a hydrazine-powered turbine that drives a hydraulic pump and various accessories through a high-speed gearbox. The APU also features a sophisticated thermal management system designed to ensure safe and reliable operation in the various launch, orbit, reentry, and landing environments.

  17. Liouville theory and special coadjoint Virasoro orbits

    OpenAIRE

    Gorsky, A.; Johansen, A.

    1993-01-01

    We describe the Hamiltonian reduction of the coajoint Kac-Moody orbits to the Virasoro coajoint orbits explicitly in terms of the Lagrangian approach for the Wess-Zumino-Novikov-Witten theory. While a relation of the coajoint Virasoro orbit $Diff \\; S^1 /SL(2,R)$ to the Liouville theory has been already studied we analyse the role of special coajoint Virasoro orbits $Diff \\; S^1/\\tilde{T}_{\\pm ,n}$ corresponding to stabilizers generated by the vector fields with double zeros. The orbits with ...

  18. Astrometric Determination of VSOP-2 Orbital Parameters

    Science.gov (United States)

    Fomalont, E.; Moellenbrock, G.; Claussen, M.

    2009-08-01

    VSOP-2 phase referencing, needed to image faint sources and to determine accurate positions, will require an orbit accuracy of about 2 cm at 23 GHz. This accuracy, however, may not be obtainable by direct orbital measurements. We propose an observation scheme, similar to that used at the VLBA, to be included during a phase referencing observation of about one orbit in order to determine a more accurate orbit determination. We show the effects of orbit errors, explain the suggested observations and reduction methods, and discuss the potential problems that might impede the use of this technique.

  19. Novel Surgical Approaches to the Orbit.

    Science.gov (United States)

    Campbell, Ashley A; Grob, Seanna R; Yoon, Michael K

    2015-01-01

    Determining safe surgical access to the orbit can be difficult given the complex anatomy and delicacy of the orbital structures. When considering biopsy or removal of an orbital tumor or repair of orbital fractures, careful planning is required to determine the ideal approach. Traditionally, this has at times necessitated invasive procedures with large incisions and extensive bone removal. The purpose of this review was to present newly techniques and devices in orbital surgery that have been reported over the past decade, with aims to provide better exposure and/or minimally invasive approaches and to improve morbidity and/or mortality.

  20. Holonomy invariance, orbital resonances, and kilohertz QPOs

    CERN Document Server

    Abramowicz, M A; Kluzniak, W; Thampan, A V; Wallinder, F

    2002-01-01

    Quantized orbital structures are typical for many aspects of classical gravity (Newton's as well as Einstein's). The astronomical phenomenon of orbital resonances is a well-known example. Recently, Rothman, Ellis and Murugan (2001) discussed quantized orbital structures in the novel context of a holonomy invariance of parallel transport in Schwarzschild geometry. We present here yet another example of quantization of orbits, reflecting both orbital resonances and holonomy invariance. This strong-gravity effect may already have been directly observed as the puzzling kilohertz quasi-periodic oscillations (QPOs) in the X-ray emission from a few accreting galactic black holes and several neutron stars.

  1. The harmonic structure of generic Kerr orbits

    CERN Document Server

    Grossman, Rebecca; Perez-Giz, Gabe

    2011-01-01

    Generic Kerr orbits exhibit intricate three-dimensional motion. We offer a classification scheme for these intricate orbits in terms of periodic orbits. The crucial insight is that for a given effective angular momentum $L$ and angle of inclination $\\iota$, there exists a discrete set of orbits that are geometrically $n$-leaf clovers in a precessing {\\it orbital plane}. When viewed in the full three dimensions, these orbits are periodic in $r-\\theta$. Each $n$-leaf clover is associated with a rational number, $1+q_{r\\theta}=\\omega_\\theta/\\omega_r$, that measures the degree of perihelion precession in the precessing orbital plane. The rational number $q_{r\\theta}$ varies monotonically with the orbital energy and with the orbital eccentricity. Since any bound orbit can be approximated as near one of these periodic $n$-leaf clovers, this special set offers a skeleton that illuminates the structure of all bound Kerr orbits, in or out of the equatorial plane.

  2. Orbital compression syndrome presenting as orbital cellulitis in a child with sickle cell anemia.

    Science.gov (United States)

    Douvoyiannis, Miltiadis; Fakioglu, Esra; Litman, Nathan

    2010-04-01

    Orbital bone infarction with subsequent orbital compression syndrome presenting as orbital cellulitis is reported in a child with sickle cell anemia. She deteriorated despite the use of antibiotics and improved after the surgical drainage of the collection. Radiographic findings, absence of sinusitis, hemorrhagic nature of the collection, and negative cultures all were consistent with orbital compression syndrome secondary to a vasoocclusive crisis. This condition needs to be differentiated from the more common orbital cellulitis secondary to sinusitis.

  3. Polarized Molecular Orbital Model Chemistry 3. The PMO Method Extended to Organic Chemistry.

    Science.gov (United States)

    Isegawa, Miho; Fiedler, Luke; Leverentz, Hannah R; Wang, Yingjie; Nachimuthu, Santhanamoorthi; Gao, Jiali; Truhlar, Donald G

    2013-01-08

    The polarized molecular orbital (PMO) method, a neglect-of-diatomic-differential-overlap (NDDO) semiempirical molecular orbital method previously parameterized for systems composed of O and H, is here extended to carbon. We modified the formalism and optimized all the parameters in the PMO Hamiltonian by using a genetic algorithm and a database containing both electrostatic and energetic properties; the new parameter set is called PMO2. The quality of the resulting predictions is compared to results obtained by previous NDDO semiempirical molecular orbital methods, both including and excluding dispersion terms. We also compare the PMO2 properties to SCC-DFTB calculations. Within the class of semiempirical molecular orbital methods, the PMO2 method is found to be especially accurate for polarizabilities, atomization energies, proton transfer energies, noncovalent complexation energies, and chemical reaction barrier heights and to have good across-the-board accuracy for a range of other properties, including dipole moments, partial atomic charges, and molecular geometries.

  4. Pyrite oxidation and reduction - Molecular orbital theory considerations. [for geochemical redox processes

    Science.gov (United States)

    Luther, George W., III

    1987-01-01

    In this paper, molecular orbital theory is used to explain a heterogeneous reaction mechanism for both pyrite oxidation and reduction. The mechanism demonstrates that the oxidation of FeS2 by Fe(3+) may occur as a result of three important criteria: (1) the presence of a suitable oxidant having a vacant orbital (in case of liquid phase) or site (solid phase) to bind to the FeS2 via sulfur; (2) the initial formation of a persulfido (disulfide) bridge between FeS2 and the oxidant, and (3) an electron transfer from a pi(asterisk) orbital in S2(2-) to a pi or pi(asterisk) orbital of the oxidant.

  5. Polarized Molecular Orbital Model Chemistry 3. The PMO Method Extended to Organic Chemistry

    Science.gov (United States)

    Isegawa, Miho; Fiedler, Luke; Leverentz, Hannah R.; Wang, Yingjie; Nachimuthu, Santhanamoorthi; Gao, Jiali; Truhlar, Donald G.

    2013-01-01

    The polarized molecular orbital (PMO) method, a neglect-of-diatomic-differential-overlap (NDDO) semiempirical molecular orbital method previously parameterized for systems composed of O and H, is here extended to carbon. We modified the formalism and optimized all the parameters in the PMO Hamiltonian by using a genetic algorithm and a database containing both electrostatic and energetic properties; the new parameter set is called PMO2. The quality of the resulting predictions is compared to results obtained by previous NDDO semiempirical molecular orbital methods, both including and excluding dispersion terms. We also compare the PMO2 properties to SCC-DFTB calculations. Within the class of semiempirical molecular orbital methods, the PMO2 method is found to be especially accurate for polarizabilities, atomization energies, proton transfer energies, noncovalent complexation energies, and chemical reaction barrier heights and to have good across-the-board accuracy for a range of other properties, including dipole moments, partial atomic charges, and molecular geometries. PMID:23704835

  6. Excitation of high orbital angular momentum Rydberg states with Laguerre-Gauss beams

    CERN Document Server

    Rodrigues, J D; Mendonça, J T

    2015-01-01

    We consider the excitation of Rydberg states through photons carrying an intrinsic orbital angular momentum degree of freedom. Laguerre-Gauss modes, with a helical wave-front structure, correspond to such a set of laser beams, which carry some units of orbital angular momentum in their propagation direction. We demonstrate that, in a proper geometrical setting, this orbital angular momentum can be transferred to the internal degrees of freedom of the atoms, thus violating the standard dipolar selection rules. Higher orbital angular momentum states become accessible through a single photon excitation process. We investigate how the spacial structure of the Laguerre-Gauss beam affects the radial coupling strength, assuming the simplest case of hydrogen-like wavefunctions. Finally we discuss a generalization of the angular momentum coupling, in order to include the effects of the fine and hyperfine splitting, in the context of the Wigner-Eckart theorem.

  7. Away from generalized gradient approximation: orbital-dependent exchange-correlation functionals.

    Science.gov (United States)

    Baerends, E J; Gritsenko, O V

    2005-08-08

    The local-density approximation of density functional theory (DFT) is remarkably accurate, for instance, for geometries and frequencies, and the generalized gradient approximations have also made bond energies quite reliable. Sometimes, however, one meets with failure in individual cases. One of the possible routes towards better functionals would be the incorporation of orbital dependence (which is an implicit density dependency) in the functionals. We discuss this approach both for energies and for response properties. One possibility is the use of the Hartree-Fock-type exchange energy expression as orbital-dependent functional. We will argue that in spite of the increasing popularity of this approach, it does not offer any advantage over Hartree-Fock for energies. We will advocate not to apply the separation of exchange and correlation, which is so ingrained in quantum chemistry, but to model both simultaneously. For response properties the energies and shapes of the virtual orbitals are crucial. We will discuss the benefits that Kohn-Sham potentials can offer which are derived from either an orbital-dependent energy functional, including the exact-exchange functional, or which can be obtained directly as orbital-dependent functional. We highlight the similarity of the Hartree-Fock and Kohn-Sham occupied orbitals and orbital energies, and the essentially different meanings the virtual orbitals and orbital energies have in these two models. We will show that these differences are beneficial for DFT in the case of localized excitations (in a small molecule or in a fragment), but are detrimental for charge-transfer excitations. Again, orbital dependency, in this case in the exchange-correlation kernel, offers a solution.

  8. Kalman Orbit Optimized Loop Tracking

    Science.gov (United States)

    Young, Lawrence E.; Meehan, Thomas K.

    2011-01-01

    Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.

  9. Technology transfer by multinationals

    OpenAIRE

    Kostyantyn Zuzik

    2003-01-01

    The paper analyses the issue of technology transfer by multinational corporations. The following questions are explored: (a) world market of technologies, the role of MNCs (b) Choice of the technology transfer mode, Dunning's OLI-theory as a factor of the choice of the mode of transfer (c) measurement and profitability of technology transfer (d) transfer of technology through partnerships, JVs, alliances and through M&As (e) aspects of technology transfer by services multinationals. Paper uti...

  10. Technology transfer by multinationals

    OpenAIRE

    2003-01-01

    The paper analyses the issue of technology transfer by multinational corporations. The following questions are explored: (a) world market of technologies, the role of MNCs (b) Choice of the technology transfer mode, Dunning's OLI-theory as a factor of the choice of the mode of transfer (c) measurement and profitability of technology transfer (d) transfer of technology through partnerships, JVs, alliances and through M&As (e) aspects of technology transfer by services multinationals. Paper uti...

  11. Solar sail time-optimal interplanetary transfer trajectory design

    Institute of Scientific and Technical Information of China (English)

    Sheng-Ping Gong; Yun-Feng Gao; Jun-Feng Li

    2011-01-01

    The fuel consumption associated with some interplanetary transfer trajectories using chemical propulsion is not affordable.A solar sail is a method of propulsion that does not consume fuel.Transfer time is one of the most pressing problems of solar sail transfer trajectory design.This paper investigates the time-optimal interplanetary transfer trajectories to a circular orbit of given inclination and radius.The optimal control law is derived from the principle of maximization.An indirect method is used to solve the optimal control problem by selecting values for the initial adjoint variables,which are normalized within a unit sphere.The conditions for the existence of the time-optimal transfer are dependent on the lightness number of the sail and the inclination and radius of the target orbit.A numerical method is used to obtain the boundary values for the time-optimal transfer trajectories.For the cases where no time-optimal transfer trajectories exist,first-order necessary conditions of the optimal control are proposed to obtain feasible solutions.The results show that the transfer time decreases as the minimum distance from the Sun decreases during the transfer duration.For a solar sail with a small lightness number,the transfer time may be evaluated analytically for a three-phase transfer trajectory.The analytical results are compared with previous results and the associated numerical results.The transfer time of the numerical result here is smaller than the transfer time from previous results and is larger than the analytical result.

  12. On-orbit Passive Thermography

    Science.gov (United States)

    Howell, Patricia A.; Winfree, William P.; Cramer, K. Elliott

    2008-01-01

    On July 12, 2006, British-born astronaut Piers Sellers became the first person to conduct thermal nondestructive evaluation experiments in space, demonstrating the feasibility of a new tool for detecting damage to the reinforced carbon-carbon (RCC) structures of the Shuttle. This new tool was an EVA (Extravehicular Activity, or spacewalk) compatible infrared camera developed by NASA engineers. Data was collected both on the wing leading edge of the Orbiter and on pre-damaged samples mounted in the Shuttle s cargo bay. A total of 10 infrared movies were collected during the EVA totaling over 250 megabytes of data. Images were downloaded from the orbiting Shuttle to Johnson Space Center for analysis and processing. Results are shown to be comparable to ground-based thermal inspections performed in the laboratory with the same type of camera and simulated solar heating. The EVA camera system detected flat-bottom holes as small as 2.54cm in diameter with 50% material loss from the back (hidden) surface in RCC during this first test of the EVA IR Camera. Data for the time history of the specimen temperature and the capability of the inspection system for imaging impact damage are presented.

  13. Kepler's Constant and WDS Orbit

    CERN Document Server

    Siregar, S

    2012-01-01

    The aim of this work are to find a Kepler's constant by using polynomial regression of the angular separation \\rho = \\rho(t) and the position angle \\theta = \\theta(t). The Kepler's constant obtained is used to derive the element of orbit. As a case study the angular separation and the position angle of the WDS 00063 +5826 and the WDS 04403-5857 were investigated. For calculating the element of orbit the Thiele-Innes van den Bos method is used. The rough data of the angular separation \\rho(t) and the position angle \\theta(t) are taken from the US Naval Observatory, Washington. This work also presents the masses and absolute bolometric magnitudes of each star.These stars include into the main-sequence stars with the spectral class G5V for WDS04403-5857and the type of spectrum G3V for WDS 00063+5826. The life time of the primary star and the secondary star of WDS 04403-5857 nearly equal to 20 Gyr. The life time of the primary star and the secondary star of WDS 00063+5826 are 20 Gyr and 19 Gyr, respectively.

  14. Fungal infections of the orbit

    Directory of Open Access Journals (Sweden)

    Bipasha Mukherjee

    2016-01-01

    Full Text Available Fungal infections of the orbit can lead to grave complications. Although the primary site of inoculation of the infective organism is frequently the sinuses, the patients can initially present to the ophthalmologist with ocular signs and symptoms. Due to its varied and nonspecific clinical features, especially in the early stages, patients are frequently misdiagnosed and even treated with steroids which worsen the situation leading to dire consequences. Ophthalmologists should be familiar with the clinical spectrum of disease and the variable presentation of this infection, as early diagnosis and rapid institution of appropriate therapy are crucial elements in the management of this invasive sino-orbital infection. In this review, relevant clinical, microbiological, and imaging findings are discussed along with the current consensus on local and systemic management. We review the recent literature and provide a comprehensive analysis. In the immunocompromised, as well as in healthy patients, a high index of suspicion must be maintained as delay in diagnosis of fungal pathology may lead to disfiguring morbidity or even mortality. Obtaining adequate diagnostic material for pathological and microbiological examination is critical. Newer methods of therapy, particularly oral voriconazole and topical amphotericin B, may be beneficial in selected patients.

  15. Introducing the Moon's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2014-11-01

    I present a novel way to introduce the lunar orbital eccentricity in introductory astronomy courses. The Moon is perhaps the clearest illustration of the general orbital elements such as inclination, ascending node, eccentricity, perigee, and so on. Furthermore, I like the students to discover astronomical phenomena for themselves, by means of a guided exercise, rather than just telling them the facts.1 The inclination and nodes may be found by direct observation, monitoring carefully the position of the Moon among the stars. Even the regression of the nodes may be discovered in this way2 To find the eccentricity from students' observations is also possible,3 but that requires considerable time and effort. if a whole class should discover it in a short time, here is a method more suitable for a one-day class or home assignment. The level I aim at is, more or less, advanced high school or first-year college students. I assume them to be acquainted with celestial coordinates and the lunar phases, and to be able to use algebra and trigonometry.

  16. The earth orbiting space debris

    Directory of Open Access Journals (Sweden)

    Rossi A.

    2005-01-01

    Full Text Available The space debris population is similar to the asteroid belt, since it is subject to a process of high-velocity mutual collisions that affects the long-term evolution of its size distribution. Presently, more than 10 000 artificial debris particles with diameters larger than 10 cm (and more than 300 000 with diameters larger than 1 cm are orbiting the Earth, and are monitored and studied by a large network of sensors around the Earth. Many objects of different kind compose the space debris population, produced by different source mechanisms ranging from high energy fragmentation of large spacecraft to slow diffusion of liquid metal. The impact against a space debris is a serious risk that every spacecraft must face now and it can be evaluated with ad-hoc algorithms. The long term evolution of the whole debris population is studied with computer models allowing the simulation of all the known source and sink mechanisms. One of these codes is described in this paper and the evolution of the debris environment over the next 100 years, under different traffic scenarios, is shown, pointing out the possible measures to mitigate the growth of the orbital debris population. .

  17. Orbital variations, climate and paleoecology.

    Science.gov (United States)

    Bartlein, P J; Prentice, I C

    1989-07-01

    One of the most exciting discoveries in the earth sciences in recent decades has been the proof that ice ages are governed by deterministic variations in the earth's orbit. These variations modify the latitudinal and seasonal distribution of solar radiation at periods ranging from 103 to 10(5) years, and alternately produce conditions for building and melting continental ice. The same solar radiation variations also govern other aspects of world climate, including the temperatures of the midlatitude continental interiors, the intensity of upwelling in the tropical oceans, and the strength and extent of the monsoons. The interplay of solar radiation, seasonality and ice-sheet changes is responsible for the complex ecological history documented in the fossil record of the past 20 000 years. But the orbital variations have occurred throughout earth's history, and have caused periodic environmental changes in both terrestrial and marine environments even during times when there was no ice. Species have responded to these changes by range migration, an evolved ability that may maintain their genetic coherence in the face of a continually changing environment.

  18. Measured force on elongated bodies in a simulated low-Earth orbit environment

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado, C. A.; Ketsdever, A. D. [University of Colorado, Colorado Springs, CO 80918 (United States); Gimelshein, S. F. [University of Southern California, Los Angeles, CA 90033 (United States)

    2014-12-09

    An overview of the development of a magnetically filtered atomic oxygen plasma source and the application of the source to study low-Earth orbit drag on elongated bodies is presented. Plasma diagnostics show that the magnetic filter plasma source produces atomic oxygen ions (O{sup +}) with streaming energies equivalent to the relative orbital environment of approximately 5eV and can supply the appropriate density for LEO simulation. Previous research has demonstrated that momentum transfer between ions and metal surfaces is equivalent to the momentum transfer expected for neutral molecules with similar energy, due to charge exchange occurring prior to momentum transfer. Total drag measurements of aluminum cuboid geometries of varying length to diameter ratios immersed in the extracted plasma plume are presented as a function of streaming ion energy.

  19. LROC - Lunar Reconnaissance Orbiter Camera

    Science.gov (United States)

    Robinson, M. S.; Eliason, E.; Hiesinger, H.; Jolliff, B. L.; McEwen, A.; Malin, M. C.; Ravine, M. A.; Thomas, P. C.; Turtle, E. P.

    2009-12-01

    The Lunar Reconnaissance Orbiter (LRO) went into lunar orbit on 23 June 2009. The LRO Camera (LROC) acquired its first lunar images on June 30 and commenced full scale testing and commissioning on July 10. The LROC consists of two narrow-angle cameras (NACs) that provide 0.5 m scale panchromatic images over a combined 5 km swath, and a wide-angle camera (WAC) to provide images at a scale of 100 m per pixel in five visible wavelength bands (415, 566, 604, 643, and 689 nm) and 400 m per pixel in two ultraviolet bands (321 nm and 360 nm) from the nominal 50 km orbit. Early operations were designed to test the performance of the cameras under all nominal operating conditions and provided a baseline for future calibrations. Test sequences included off-nadir slews to image stars and the Earth, 90° yaw sequences to collect flat field calibration data, night imaging for background characterization, and systematic mapping to test performance. LRO initially was placed into a terminator orbit resulting in images acquired under low signal conditions. Over the next three months the incidence angle at the spacecraft’s equator crossing gradually decreased towards high noon, providing a range of illumination conditions. Several hundred south polar images were collected in support of impact site selection for the LCROSS mission; details can be seen in many of the shadows. Commissioning phase images not only proved the instruments’ overall performance was nominal, but also that many geologic features of the lunar surface are well preserved at the meter-scale. Of particular note is the variety of impact-induced morphologies preserved in a near pristine state in and around kilometer-scale and larger young Copernican age impact craters that include: abundant evidence of impact melt of a variety of rheological properties, including coherent flows with surface textures and planimetric properties reflecting supersolidus (e.g., liquid melt) emplacement, blocks delicately perched on

  20. Magnonic Charge Pumping via Spin-Orbit Coupling

    Science.gov (United States)

    Ciccarelli, Chiara; Hals, Kjetil; Irvine, Andrew; Novak, Vit; Tserkovnyak, Yaroslav; Kurebayashi, Hidekazu; Brataas, Arne; Ferguson, Andrew

    2015-03-01

    The interplay between spin, charge and orbital degrees of freedom has led to the development of spintronic devices such as spin-torque oscillators and spin-transfer torque MRAM. In this development, spin pumping represents a convenient way to electrically detect magnetization dynamics. The effect originates from direct conversion of low-energy quantized spin waves in the magnet, known as magnons, into a flow of spins from the precessing magnet to adjacent leads. In this case, a secondary spin-charge conversion element, such as heavy metals with large spin Hall angle or multilayer layouts, is required to convert the spin current into a charge signal. Here, we report the observation of charge pumping in which a precessing ferromagnet pumps a charge current, demonstrating direct conversion of magnons into high-frequency currents via spin-orbit interaction. The generated electric current, unlike spin currents generated by spin-pumping, can be directly detected without the need of any additional spin-charge conversion mechanism. The charge-pumping phenomenon is generic and gives a deeper understanding of its reciprocal effect, the spin orbit torque, which is currently attracting interest for their potential in manipulating magnetic information.

  1. 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.

  2. Spin transport at interfaces with spin-orbit coupling: Formalism

    Science.gov (United States)

    Amin, V. P.; Stiles, M. D.

    2016-09-01

    We generalize magnetoelectronic circuit theory to account for spin transfer to and from the atomic lattice via interfacial spin-orbit coupling. This enables a proper treatment of spin transport at interfaces between a ferromagnet and a heavy-metal nonmagnet. This generalized approach describes spin transport in terms of drops in spin and charge accumulations across the interface (as in the standard approach), but additionally includes the responses from in-plane electric fields and offsets in spin accumulations. A key finding is that in-plane electric fields give rise to spin accumulations and spin currents that can be polarized in any direction, generalizing the Rashba-Edelstein and spin Hall effects. The spin accumulations exert torques on the magnetization at the interface when they are misaligned from the magnetization. The additional out-of-plane spin currents exert torques via the spin-transfer mechanism on the ferromagnetic layer. To account for these phenomena we also describe spin torques within the generalized circuit theory. The additional effects included in this generalized circuit theory suggest modifications in the interpretations of experiments involving spin-orbit torques, spin pumping, spin memory loss, the Rashba-Edelstein effect, and the spin Hall magnetoresistance.

  3. COLD-SAT - An orbital cryogenic hydrogen technology experiment

    Science.gov (United States)

    Schuster, J. R.; Wachter, Joseph P.; Powers, Albert G.

    1989-01-01

    The COLD-SAT spacecraft will perform subcritical liquid hydrogen storage and transfer experiments under low-gravity conditions to provide engineering data for future space transportation missions. Consisting of an experiment module mated to a spacecraft bus, COLD-SAT will be placed in an initial 460 km circular orbit by an Atlas I commercial launch vehicle. After deployment, the three-axis-controlled spacecraft bus will provide electric power, experiment control and data management, communications, and attitude control along with propulsive acceleration levels ranging from 10 (-6) to 10(-4) g. These accelerations are an important aspect of some of the experiments, as it is desired to know the effects that low gravity levels might have on the heat and mass transfer processes involved. The experiment module will contain the three liquid hydrogen tanks, valves, pressurization equipment, and instrumentation. At launch all the hydrogen will be in the largest tank, which has helium-purged MLI and is loaded and topped off by the hydrogen tanking system used for the Centaur upper stage of the Atlas. The two smaller tanks will be utilized in orbit for performing some of the experiments. The experiments are grouped into two classes on the basis of their priority, and include six regarded as enabling technology and nine regarded as enhancing technology.

  4. COLD-SAT: An orbital cryogenic hydrogen technology experiment

    Science.gov (United States)

    Schuster, J. R.; Wachter, Joseph P.; Powers, Albert G.

    1989-01-01

    The COLD-SAT spacecraft will perform subcritical liquid hydrogen storage and transfer experiments under low-gravity conditions to provide engineering data for future space transportation missions. Consisting of an experiment module mated to a spacecraft bus, COLD-SAT will be placed in an initial 460 km circular orbit by an Atlas I commercial launch vehicle. After deployment, the three-axis-controlled spacecraft bus will provide electric power, experiment control and data management, communications, and attitude control along with propulsive acceleration levels ranging from 10(-6) to 10(-4)g. These accelerations are an important aspect of some of the experiments, as it is desired to know the effects that low gravity levels might have on the heat and mass transfer processes involved. The experiment module will contain the three liquid hydrogen tanks, valves, pressurization equipment, and instrumentation. At launch all the hydrogen will be in the largest tank, which has helium-purged MLI and is loaded and topped off by the hydrogen tanking system used for the Centaur upper stage of the Atlas. The two smaller tanks will be utilized in orbit for performing some of the experiments. The experiments are grouped into two classes on the basis of their priority, and include six regarded as enabling technology and nine regarded as enhancing technology.

  5. Analytical representations of precise orbit predictions for Earth orbiting space objects

    Science.gov (United States)

    Sang, Jizhang; Li, Bin; Chen, Junyu; Zhang, Pin; Ning, Jinsheng

    2017-01-01

    Accurate orbits of Earth orbiting space objects are usually generated from an orbit determination/prediction process using numerical integrators, and presented to users in a tabulated form or a state vector including force model parameters. When dealing with hundreds of thousands of space objects such as in the space conjunction assessment, the memory required for the tabulated orbits or the computing time for propagating orbits using the state vector are both confronting to users. This paper presents two methods of analytically representing numerical orbits considering the accuracy, computing efficiency and memory. The first one is a two-step TLE-based method in which the numerical orbits are first fitted into a TLE set and then correction functions are applied to improve the position accuracy. In the second method, the orbit states are represented in equinoctial elements first, and then again correction functions are applied to reduce the position errors. Experiments using six satellite laser ranging (SLR) satellites and 12 debris objects with accurate orbits show that both methods can represent the accurate orbits over 5 days in an accuracy of a few dozens of meters for the circular orbits and several hundred meters for the eccentric orbits. The computing time is similar to that using the NORAD TLE/SGP4 algorithm, and storage for the orbit elements and function coefficients is about 3-5 KB. These features could make the two methods beneficial for the maintenance of orbit catalog of large numbers of space objects.

  6. Homoclinic Bifurcation of Orbit Flip with Resonant Principal Eigenvalues

    Institute of Scientific and Technical Information of China (English)

    Tian Si ZHANG; De Ming ZHU

    2006-01-01

    Codimension-3 bifurcations of an orbit-flip homoclinic orbit with resonant principal eigenvalues are studied for a four-dimensional system. The existence, number, co-existence and non-coexistence of 1-homoclinic orbit, 1-periodic orbit, 2n-homoclinic orbit and 2n-periodic orbit are obtained. The bifurcation surfaces and existence regions are also given.

  7. Degenerate Orbit Flip Homoclinic Bifurcations with Higher Dimensions

    Institute of Scientific and Technical Information of China (English)

    Ran Chao WU; Jian Hua SUN

    2006-01-01

    Bifurcations of a degenerate homoclinic orbit with orbit flip in high dimensional system are existence and uniqueness of 1-homoclinic orbit and 1-periodic orbit are given. Also considered is the existence of 2-homoclinic orbit and 2-periodic orbit. In additon, the corresponding bifurcation surfaces are given.

  8. The Jupiter Ganymede Orbiter mission and spacecraft architecture

    Science.gov (United States)

    Boulade, Sebastien; Maliet, Eric; Saks, Noah; Lang, Rainer; Kemble, Steve

    2010-05-01

    . The inter-planetary transfer will take about 5.9 years. The initial Jovian orbit will be followed by a total of four Ganymede and Callisto swing-by manoeuvres. JGO will then be injected into a resonant orbit around Callisto, providing good surface coverage. Through another swing by sequence, the Orbiter will be injected into an elliptical orbit around Ganymede , to be circularized later in the mission. The whole mission duration in the Jovian environment will last 3.5 years. Astrium is leading an assessment study of the Jupiter Ganymede Orbiter programme for ESA. In this framework, Astrium has defined a cost-efficient spacecraft architecture, based on successful experience on ESA interplanetary missions (Rosetta, Mars Express, Venus Express) and offers innovative solutions for the main challenges of the JGO mission (high radiations and low illumination environment, long distance and long duration mission requiring high autonomy, navigation concepts). The spacecraft design is presented, including the accommodation of the set of payload instruments.

  9. Active Debris Removal mission design in Low Earth Orbit

    Science.gov (United States)

    Martin, Th.; Pérot, E.; Desjean, M.-Ch.; Bitetti, L.

    2013-03-01

    Active Debris Removal (ADR) aims at removing large sized intact objects ― defunct satellites, rocket upper-stages ― from space crowded regions. Why? Because they constitute the main source of the long-term debris environment deterioration caused by possible future collisions with fragments and worse still with other intact but uncontrolled objects. In order to limit the growth of the orbital debris population in the future (referred to as the Kessler syndrome), it is now highly recommended to carry out such ADR missions, together with the mitigation measures already adopted by national agencies (such as postmission disposal). At the French Space Agency, CNES, and in the frame of advanced studies, the design of such an ADR mission in Low Earth Orbit (LEO) is under evaluation. A two-step preliminary approach has been envisaged. First, a reconnaissance mission based on a small demonstrator (˜500 kg) rendezvousing with several targets (observation and in-flight qualification testing). Secondly, an ADR mission based on a larger vehicle (inherited from the Orbital Transfer Vehicle (OTV) concept) being able to capture and deorbit several preselected targets by attaching a propulsive kit to these targets. This paper presents a flight dynamics level tradeoff analysis between different vehicle and mission concepts as well as target disposal options. The delta-velocity, times, and masses required to transfer, rendezvous with targets and deorbit are assessed for some propelled systems and propellant less options. Total mass budgets are then derived for two end-to-end study cases corresponding to the reconnaissance and ADR missions mentioned above.

  10. Continuation of Sets of Constrained Orbit Segments

    DEFF Research Database (Denmark)

    Schilder, Frank; Brøns, Morten; Chamoun, George Chaouki

    Sets of constrained orbit segments of time continuous flows are collections of trajectories that represent a whole or parts of an invariant set. A non-trivial but simple example is a homoclinic orbit. A typical representation of this set consists of an equilibrium point of the flow and a trajecto...... orbit segments, this is very disadvantageous in practice. In this talk we will present an algorithm that allows the efficient continuation of sets of constrained orbit segments together with the solution of the full variational problem.......Sets of constrained orbit segments of time continuous flows are collections of trajectories that represent a whole or parts of an invariant set. A non-trivial but simple example is a homoclinic orbit. A typical representation of this set consists of an equilibrium point of the flow and a trajectory...

  11. Orbital behavior around a nonuniform celestial body

    Science.gov (United States)

    Rosson, Z.; Hall, F.; Vogel, T.

    2016-09-01

    To effectively model the orbit around a nonuniform celestial body, detailed information needs to be determined of the perturbations. This research looked at one of the most crucial perturbations: the nonuniform gravitational field of a celestial body. Given an orbiting particle (a satellite), we utilized numerical methods to calculate its orbit in two dimensions around a discretized center mass structure. The gravitational acceleration imposed on the particle due to each mass point sums vectorally as the particle completes each infinitesimal time step of one orbit. There are noticeable effects on the orbit as the conditions of the center mass change. The development of a simulation code allows for the modelling of the orbit about an irregular body with satisfactory accuracy.

  12. On Orbital Period Changes in Nova Outbursts

    CERN Document Server

    Martin, Rebecca G; Schaefer, Bradley E

    2011-01-01

    We propose a new mechanism that produces an orbital period change during a nova outburst. When the ejected material carries away the specific angular momentum of the white dwarf, the orbital period increases. A magnetic field on the surface of the secondary star forces a fraction of the ejected material to corotate with the star, and hence the binary system. The ejected material thus takes angular momentum from the binary orbit and the orbital period decreases. We show that for sufficiently strong magnetic fields on the surface of the secondary star, the total change to the orbital period could even be negative during a nova outburst, contrary to previous expectations. Accurate determinations of pre- and post-outburst orbital periods of recurrent nova systems could test the new mechanism, in addition to providing meaningful constraints on otherwise difficult to measure physical quantities. We apply our mechanism to outbursts of the recurrent nova U Sco.

  13. Transfer Readiness Pilot Study.

    Science.gov (United States)

    Scott-Skillman, Thelma; And Others

    The California Community Colleges (CCC) has implemented a prototype model for determining student transfer readiness as a primary means of assessing community college transfer effectiveness. This report provides definitions of transfer readiness and guidelines for colleges participating in the CCC transfer readiness study. First, a memorandum from…

  14. Making benefit transfers work

    DEFF Research Database (Denmark)

    Bateman, I.J.; Brouwer, R.; Ferrini, S.

    We develop and test guidance principles for benefits transfers. These argue that when transferring across relatively similar sites, simple mean value transfers are to be preferred but that when sites are relatively dissimilar then value function transfers will yield lower errors. The paper also...

  15. Ray transfer matrix for a spiral phase plate.

    Science.gov (United States)

    Eggleston, M; Godat, T; Munro, E; Alonso, M A; Shi, H; Bhattacharya, M

    2013-12-01

    We present a ray transfer matrix for a spiral phase plate. Using this matrix we determine the stability of an optical resonator made of two spiral phase plates and trace stable ray orbits in the resonator. Our results should be relevant to laser physics, optical micromanipulation, quantum information, and optomechanics.

  16. Wireless power transfer for electric vehicles and mobile devices

    CERN Document Server

    Rim, Chun T

    2017-01-01

    From mobile, cable-free re-charging of electric vehicles, smart phones and laptops to collecting solar electricity from orbiting solar farms, wireless power transfer (WPT) technologies offer consumers and society enormous benefits. Written by innovators in the field, this comprehensive resource explains the fundamental principles and latest advances in WPT and illustrates key applications of this emergent technology.

  17. Optimal Low Energy Earth-Moon Transfers

    Science.gov (United States)

    Griesemer, Paul Ricord; Ocampo, Cesar; Cooley, D. S.

    2010-01-01

    The optimality of a low-energy Earth-Moon transfer is examined for the first time using primer vector theory. An optimal control problem is formed with the following free variables: the location, time, and magnitude of the transfer insertion burn, and the transfer time. A constraint is placed on the initial state of the spacecraft to bind it to a given initial orbit around a first body, and on the final state of the spacecraft to limit its Keplerian energy with respect to a second body. Optimal transfers in the system are shown to meet certain conditions placed on the primer vector and its time derivative. A two point boundary value problem containing these necessary conditions is created for use in targeting optimal transfers. The two point boundary value problem is then applied to the ballistic lunar capture problem, and an optimal trajectory is shown. Additionally, the ballistic lunar capture trajectory is examined to determine whether one or more additional impulses may improve on the cost of the transfer.

  18. Cryogenic heat transfer

    CERN Document Server

    Barron, Randall F

    2016-01-01

    Cryogenic Heat Transfer, Second Edition continues to address specific heat transfer problems that occur in the cryogenic temperature range where there are distinct differences from conventional heat transfer problems. This updated version examines the use of computer-aided design in cryogenic engineering and emphasizes commonly used computer programs to address modern cryogenic heat transfer problems. It introduces additional topics in cryogenic heat transfer that include latent heat expressions; lumped-capacity transient heat transfer; thermal stresses; Laplace transform solutions; oscillating flow heat transfer, and computer-aided heat exchanger design. It also includes new examples and homework problems throughout the book, and provides ample references for further study.

  19. High Precision Orbit Determination of CHAMP Satellite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qile; LIU Jingnan; GE Maorong

    2006-01-01

    The precision orbit determination of challenging minisatellite payload(CHAMP) satellite was done based on position and navigation data analyst(PANDA) software which is developed in Wuhan University, using the onboard GPS data of year 2002 from day 126 to 131. The orbit accuracy was assessed by analyzing the difference from GFZ post-processed science orbits (PSO), the GPS carrier and pseudo-range data residuals and the satellite laser ranging (SLR) residuals.

  20. Wavefunction Intensity Statistics from Unstable Periodic Orbits

    CERN Document Server

    Kaplan, L

    1998-01-01

    We examine the effect of short unstable periodic orbits on wavefunction statistics in a classically chaotic system, and find that the tail of the wavefunction intensity distribution in phase space is dominated by scarring associated with the least unstable periodic orbits. In an ensemble average over systems with classical orbits of different instabilities, a power law tail is found, in sharp contrast to the exponential prediction of random matrix theory. The calculations are compared with numerical data and quantitative agreement is obtained