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1

A modified proportional navigation scheme for rendezvous and docking with tumbling targets: The Planar case  

NASA Technical Reports Server (NTRS)

A two-phase proportional navigation scheme is developed for the case of two rigid bodies engaged in a rendezvous/docking maneuver. The target vehicle is nonmaneuvering, but does have constant nonzero angular and linear velocities. Under these conditions, it is shown that previously obtained solutions are not applicable. Analytical solutions are obtained leading to relationships between the transverse and LOS navigation constants. It is shown that the transverse navigation constant for the second phase of the maneuver must be 2. Also, initial conditions necessary for rendezvous are presented.

Fitz-Coy, Norman; Liu, Ming-Cheng

1995-01-01

2

Nonlinearity-induced spacecraft tumbling  

SciTech Connect

An existing tumbling criterion for the dumbbell satellite in planar librations is reexamined and modified to reflect a recently identified tumbling mode associated with the horizontal attitude orientation. It is shown that for any initial attitude there exists a critical angular rate below which the motion is oscillatory and harmonic and beyond which a continuous tumbling will ensue. If the angular rate is at the critical value the spacecraft drifts towards the horizontal attitude from which a spontaneous periodic tumbling occurs.

Amos, A.K. [Pennsylvania State Univ., University Park, PA (United States)

1994-12-31

3

Side Effects of Collisions: Spin Rate Changes, Tumbling Rotation States, and Binary Asteroids  

NASA Astrophysics Data System (ADS)

Energetic collisions in the asteroid belt produce several observable effects, altering their size distribution and rotational properties. Moreover, interesting objects or systems may be created: dynamical families, or binaries, and asteroids in unusual rotation states (fast rotators or tumbling bodies). While the evolution of the size distribution and properties of families as well as binaries are discussed in separate chapters, the other relevant effects of collisions will be dealt with here. During collisions, both the projectile and the target bring their own spin and orbital angular momenta to the system. In the collision the fragments may acquire a "breakup spin" connected to the breakup process. The "breakup spin" is related to the ejection velocity and size of the fragment; fast and small ejecta can achieve rapid spin rates. Usually, freshly created fragments leaving a collisional site do not spin around their axis of maximum momentum of inertia; thus, tumbling (observed also in laboratory experiments) is "natural." The presence of dissipative processes damps the wobbling, with a timescale that is usually short compared to the age of the solar system. Observations of main-belt asteroids suggest a lower limit of ~2 h to their spin periods. Very fast rotators, which must be monolithic bodies held together by internal strength, are present only among the smallest observed asteroids (all of which are NEAs, owing to obvious selection effects). Several asteroids have very long rotational periods, which remains puzzling. Theoretical arguments give preliminary and qualitative explanations for the observed properties. Asteroidal binary systems are an expected outcome from catastrophic collisions, through the effect of the mutual gravitational interaction or as a consequence of later bursting fission.

Paolicchi, P.; Burns, J. A.; Weidenschilling, S. J.

4

Usage and User Experience of Communication before and during Rendezvous  

ERIC Educational Resources Information Center

This paper reports a field evaluation of the mobile phone as a "package" of device and services. The evaluation compares 44 university students' usage and user experience of communication before and during rendezvous. During a rendezvous (en route), students rated many aspects of the experience of phone use less favourably than before a rendezvous

Colbert, Martin

2005-01-01

5

Tumbling in pigeons  

Microsoft Academic Search

THE spectacular hereditary trait of backward somersaulting by Tumbler pigeons has been known since 1600 AD1 and was described by Darwin as ``... one of the most remarkable inherited habits or instincts ever recorded ...''2. The potentially important physiological mechanism of tumbling is unknown, largely because the extreme rapidity of the somersaulting blurs visual observation of the component motions3-9. Filming

Richard K. Entrikin; S. H. Bryant

1974-01-01

6

Tumbling of Small Axisymmetric Particles in Random and Turbulent Flows  

NASA Astrophysics Data System (ADS)

We analyze the tumbling of small nonspherical, axisymmetric particles in random and turbulent flows. We compute the orientational dynamics in terms of a perturbation expansion in the Kubo number, and obtain the tumbling rate in terms of Lagrangian correlation functions. These capture preferential sampling of the fluid gradients, which in turn can give rise to differences in the tumbling rates of disks and rods. We show that this is a weak effect in Gaussian random flows. But in turbulent flows persistent regions of high vorticity cause disks to tumble much faster than rods, as observed in direct numerical simulations [S. Parsa, E. Calzavarini, F. Toschi, and G. A. Voth, Phys. Rev. Lett. 109, 134501 (2012), 10.1103/PhysRevLett.109.134501]. For larger particles (at finite Stokes numbers), rotational and translational inertia affects the tumbling rate and the angle at which particles collide, due to the formation of rotational caustics.

Gustavsson, K.; Einarsson, J.; Mehlig, B.

2014-01-01

7

Rendezvous effects in the diffusion process on bipartite metapopulation networks  

NASA Astrophysics Data System (ADS)

Epidemic outbreaks have been shown to be closely related to the rendezvous-induced transmission of infection, which is caused by casual contact with infected individuals in public gatherings. To investigate rendezvous effects in the spread of infectious diseases, we propose an epidemic model on metapopulation networks bipartite-divided into two sets of location and rendezvous nodes. At a given transition rate ?kk'p, each individual transfers from location k to rendezvous p (where rendezvous-induced disease incidence occurs) and thereafter moves to location k'. We find that the eigenstructure of a transition-rate-dependent matrix determines the epidemic threshold condition. Both analytical and numerical results show that rendezvous-induced transmission accelerates the progress of infectious diseases, implying the significance of outbreak control measures including prevention of public gatherings or decentralization of a large-scale rendezvous into downsized ones.

Cao, Lang; Li, Xun; Wang, Bing; Aihara, Kazuyuki

2011-10-01

8

Rough and Tumble Play 101  

ERIC Educational Resources Information Center

Many people fear that play-fighting or rough and tumble play is the same as real fighting. There is also a fear that this rough play will become real fighting if allowed to continue. Most of all, parents and teachers fear that during the course of rough and tumble play a child may be hurt. To provide for and allow children to play rough without…

Carlson, Frances

2009-01-01

9

Rendezvous Docking Simulator  

NASA Technical Reports Server (NTRS)

Rendezvous Docking Simulator. The simulation demonstrated linear and gimbal motions of the capsule and a Gemini-Agena docking. [Entire movie available on DVD from CASI as Doc ID 20070030983. Contact help@sti.nasa.gov

1963-01-01

10

The NEAR Rendezvous Burn Anomaly  

E-print Network

The NEAR Rendezvous Burn Anomaly of December 1998 Final Report of the NEAR (Near Earth Asteroid Report of the NEAR (Near Earth Asteroid Rendezvous) Anomaly Review Board November 1999 ©1999 The Johns .................................................................................................................................................... 4 Reconstructed Timeline

Rhoads, James

11

Tumbling dynamics of flexible wings  

NASA Astrophysics Data System (ADS)

We are broadly interested in elucidating the role of flexibility in passive flight. In particular, we examine the role of bending on the flight of autorotating winged seedpods through an experimental investigation of tumbling rectangular paper strips freely falling in air. Our results suggest the existence of a critical length above which the wing bends. We develop a theoretical model that demonstrates that this buckling is prompted by inertial forces associated with the tumbling motion, and yields a buckling criterion consistent with that observed. We further develop a reduced model for the flight dynamics of flexible tumbling wings, that illustrates the effect of aeroelastic coupling on flight characteristics and explains experimentally observed variations in the wing's falling speed and range. Other modes of flexible passive flight are discussed as well as biological implications for the dispersal of seed pods.

Tam, Daniel; Bush, John; Robitaille, Michael; Kudrolli, Arshad

2009-11-01

12

Gemini Rendezvous Docking Simulator  

NASA Technical Reports Server (NTRS)

Gemini Rendezvous Docking Simulator suspended from the roof of the Langley Research Center's aircraft hanger. Francis B. Smith wrote: 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.'

1964-01-01

13

Rendezvous with Zarya  

NASA Technical Reports Server (NTRS)

Backdropped against a blanket of heavy cloud cover, the Russian-built FGB, also called Zarya, nears the Space Shuttle Endeavour and the U.S.-built Node 1, also called Unity (foreground). Inside Endeavour's cabin, the STS-88 crew readies the Remote Manipulator System (RMS) for Zarya capture as they await the carefully choreographed dance of the rendezvous.

1998-01-01

14

A Guidance and Navigation Strategy for Rendezvous and Proximity Operations with a Noncooperative Spacecraft in Geosynchronous Orbit  

NASA Astrophysics Data System (ADS)

The feasibility and benefits of various spacecraft servicing concepts are currently being assessed, and all require that servicer spacecraft perform rendezvous, proximity operations, and capture operations with the spacecraft to be serviced. There are many high-value commercial and military spacecraft located in geosynchronous orbit (GEO) which may be candidates for servicing, but GEO is a regime in which rendezvous and capture operations are not commonplace; further, most GEO spacecraft were not designed to be cooperative rendezvous targets, and some may even be completely nonfunctional and therefore potentially tumbling. In this work we present elements of a guidance and navigation strategy for rendezvous and proximity operations with a noncooperative spacecraft in GEO. Translational ?v is assessed for a passively safe co-elliptic rendezvous approach sequence that is followed by injection into a safety ellipse about a noncooperative tumbling spacecraft and, ultimately, final approach to capture. Covariance analysis is presented for a simulation of range and bearing measurements throughout the rendezvous and proximity operations sequence.

Barbee, Brent W.; Carpenter, J. Russell; Heatwole, Scott; Markley, F. Landis; Moreau, Michael; Naasz, Bo J.; Van Eepoel, John

2011-07-01

15

Tumbling of a rigid rod in a shear flow  

NASA Astrophysics Data System (ADS)

The tumbling of a rigid rod in a shear flow is analyzed in the high viscosity limit. Following Burgers, the Master Equation is derived for the probability distribution of the orientation of the rod. The equation contains one dimensionless number, the Weissenberg number, which is the ratio of the shear rate and the orientational diffusion constant. The equation is solved for the stationary state distribution for arbitrary Weissenberg numbers, in particular for the limit of high Weissenberg numbers. The stationary state gives an interesting flow pattern for the orientation of the rod, showing the interplay between flow due to the driving shear force and diffusion due to the random thermal forces of the fluid. The average tumbling time and tumbling frequency is calculated as a function of the Weissenberg number. A simple crossover function is proposed which covers the whole regime from small to large Weissenberg numbers.

van Leeuwen, J. M. J.; Blöte, H. W. J.

2014-09-01

16

On the tumbling toast problem  

NASA Astrophysics Data System (ADS)

A didactical revisitation of the so-called tumbling toast problem is presented here. The numerical solution of the related Newton's equations has been found in the space domain, without resorting to the complete time-based law of motion, with a considerable reduction of the mathematical complexity of the problem. This could allow the effect of the different physical mechanisms ruling the overall dynamics to be appreciated in a more transparent way, even by undergraduates. Moreover, the availability from the literature of experimental investigations carried out on tumbling toast allows us to propose different theoretical models of growing complexity in order to show the corresponding improvement of the agreement between theory and observation.

Borghi, Riccardo

2012-09-01

17

Rendezvous Docking Simulator  

NASA Technical Reports Server (NTRS)

Multiple exposure of Rendezvous Docking Simulator. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. The controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.

1964-01-01

18

Rendezvous BET Program  

NASA Technical Reports Server (NTRS)

Computes relative positions of two vehicles in concentric orbits. LRBET3 program best-estimate-of-trajectory (BET) calculation for postflight trajectory analysis of Shuttle orbital rendezvous maneuvers. LRBET3 produces estimated measurements for reconstructing relative positions of two vehicles. Kalman filter and smoothing filter applied to relative measurement input data to estimate state vector, reduce noise, and produce BET output. BET calculation minimizes variances of all trajectory estimation errors. LRBET3 written in FORTRAN IV for batch execution.

Lear, W. M.

1986-01-01

19

Apollo Project - Rendezvous  

NASA Technical Reports Server (NTRS)

Originally the Rendezvous was used by the astronauts preparing for Gemini missions. The Rendezvous Docking Simulator was then modified and used to develop docking techniques for the Apollo program. By 1966, it was noted by A.W. Vogeley (in the paper cited below) that: 'since emphasis on space docking is decreasing, the facility is being modified to serve as a closed-circuit TV carriage. It will view an HO-scale model of a Kennedy Airport runway in the study of Category II (break-out at 100 feet) landing problems. This simulation technique is considered adequate in this case because of the large model-scale and because visibility under Category II conditions is often rather poor. Peripheral vision will also be supplied in these studies (which is not generally the case) - an important requirement, particularly where rapid decisions (upon break-out) must be made.' This last simulation application is shown as it was displayed for a public open house at Langley Research Center. From A.W. Vogeley, 'Piloted Space-Flight Simulation at Langley Research Center,' Paper presented at the American Society of Mechanical Engineers, 1966 Winter Meeting, New York, NY, November 27 - December 1, 1966. 'The Rendezvous Docking Simulator and also the Lunar Landing Research Facility are both rather large moving-base simulators. It should be noted, however, that neither was built primarily because of its motion characteristics. The main reason they were built was to provide a realistic visual scene. A secondary reason was that they would provide correct angular motion cues (important in control of vehicle short-period motions) even though the linear acceleration cues would be incorrect.'

1967-01-01

20

Cooperative control of UAV rendezvous  

Microsoft Academic Search

The cooperative control of timing and synchronization of tasks of multiple unmanned air vehicles (UAVs) represents a valuable capability for a wide range of potential multi-UAV missions. This research addresses the specific problem of cooperative rendezvous in which multiple UAVs are to arrive at their targets simultaneously. The development of a rendezvous manager state machine and a cooperative control decomposition

T. W. McLain; Phillip R. Chandler; Steven Rasmussen; Meir Pachter

2001-01-01

21

Kazakhstan's Currency Tumbles  

NSDL National Science Digital Library

This week's In the News follows economic conditions in the former Soviet Republic of Kazakhstan. The seven resources discussed provide news, government links, and background information on Kazakhstan and its currency. Following a Kazahk National Bank announcement ending government limitations on currency exchange, the tenge fell in value from 88.30 tenge to the dollar on April 2, 1999 to 150.00 tenge to the dollar on April 6, 1999. The decision allows Kazakhstan's currency to float freely on international exchange markets and has resulted in some criticism from the International Monetary Fund (IMF). According to the IMF's representative Paul Ross, the decision should stimulate economic growth in this once-industrial economy, but it may come at some social cost. Currently, Kazahk citizens may exchange their bank deposits at pre-fall rates to the dollar providing they do not withdraw their savings for nine months, and as the BBC reports, many shop keepers in the commercial capital of Almaty have already doubled their prices.

Waters, Megan.

1999-01-01

22

Multiple asteroid rendezvous missions  

NASA Technical Reports Server (NTRS)

Asteroid missions, centered on multiple asteroid rendezvous missions to main belt asteroids, are discussed and the required solar electric propulsion for these missions as well as the current performance estimates are examined. A brief statistical analysis involving asteroid availability transfer requirements and propulsion system capabilities is given, leading to a prediction that 5 to 8 asteroids can be encountered with a single launch. Measurement techniques include visual imaging, radio tracking, magnetometry, and in the case of landers, seismometry. The spacecraft will be propelled by a solar electric system with a power level of 25 kW to 40 kW and tour possibilities for 13 different asteroids have been developed. Preliminary estimates of asteroid triaxiality are made to calculate the effect of close orbits.

Bender, D. F.; Friedlander, A. L.

1979-01-01

23

An extension of generalized Taylor dispersion in unbounded homogeneous shear flows to run-and-tumble chemotactic bacteria  

E-print Network

-and-tumble chemotactic bacteria R. N. Bearon School of Oceanography, Box 357940, University of Washington, Seattle of flow, the biased random walk of bacteria such as Escherichia coli is modeled by straight runs. In the well-studied situation of weak bias in tumble rate, bacteria disperse over a diffusive time scale

Bearon, Rachel

24

Maximising somersault rotation in tumbling.  

PubMed

Performing complex somersaulting skills during the flight phase of tumbling requires the generation of linear and angular momenta during the approach and takeoff phases. This paper investigates how approach characteristics and takeoff technique affect performance with a view to maximising somersault rotation in tumbling. A five-segment planar simulation model, customised to an elite gymnast, was used to produce a simulation which closely matched a recorded performance of a double layout somersault by the elite gymnast. Three optimisations were carried out to maximise somersault rotation with different sets of initial conditions. Using the same initial linear and angular momentum as the double layout somersault and varying the joint torque activation timings allowed a double straight somersault to be performed with 19% more rotation potential than the actual performance. Increasing the approach velocity to a realistic maximum of 7 ms(-1) resulted in a 42% reduction in rotation potential when the activation timings were unchanged but allowed a triple layout somersault to be performed with an increase of 31% in rotation potential when activation timings were re-optimised. Increasing also the initial angular momentum to a realistic maximum resulted in a 4% reduction in rotation potential when the activation timings were unchanged but allowed a triple straight somersault to be performed with a further increase of 9% in rotation potential when activation timings were re-optimised. It is concluded that the limiting factor to maximising somersault rotation is the ability to generate high linear and angular velocities during the approach phase coupled with the ability to adopt consonant activation timings during the takeoff phase. PMID:14996558

King, M A Mark A; Yeadon, M R Maurice R

2004-04-01

25

STS-135: Rendezvous Pitch Maneuver  

NASA Video Gallery

On July 10, 2011, space shuttle Atlantis performed the nine-minute Rendezvous Pitch Maneuver, or â??backflip.â?ť With Commander Chris Ferguson at the helm, Atlantis rotated 360 degrees backward to ...

26

STS-133: Rendezvous Pitch Maneuver  

NASA Video Gallery

At 1:15 p.m. EST Saturday, space shuttle Discovery began the nine-minute Rendezvous Pitch Maneuver, or "backflip." With Commander Steve Lindsey at the helm, Discovery rotated 360 degrees backward t...

27

Tumbling Dynamics of Passive Flexible Wings  

NASA Astrophysics Data System (ADS)

The influence of flexibility on the flight of autorotating winged seedpods is examined through an experimental investigation of tumbling rectangular paper strips freely falling in air. Our results suggest the existence of a critical length above which the wing bends. We develop a theoretical model that demonstrates that this buckling is prompted by inertial forces associated with the tumbling motion, and yields a buckling criterion consistent with that observed. We further develop a reduced model for the flight dynamics of flexible tumbling wings that illustrates the effect of aeroelastic coupling on flight characteristics and rationalizes experimentally observed variations in the wing’s falling speed and range.

Tam, Daniel; Bush, John W. M.; Robitaille, Michael; Kudrolli, Arshad

2010-05-01

28

History of Space Shuttle Rendezvous  

NASA Technical Reports Server (NTRS)

This technical history is intended to provide a technical audience with an introduction to the rendezvous and proximity operations history of the Space Shuttle Program. It details the programmatic constraints and technical challenges encountered during shuttle development in the 1970s and over thirty years of shuttle missions. An overview of rendezvous and proximity operations on many shuttle missions is provided, as well as how some shuttle rendezvous and proximity operations systems and flight techniques evolved to meet new programmatic objectives. This revised edition provides additional information on Mercury, Gemini, Apollo, Skylab, and Apollo/Soyuz. Some chapters on the Space Shuttle have been updated and expanded. Four special focus chapters have been added to provide more detailed information on shuttle rendezvous. A chapter on the STS-39 mission of April/May 1991 describes the most complex deploy/retrieve mission flown by the shuttle. Another chapter focuses on the Hubble Space Telescope servicing missions. A third chapter gives the reader a detailed look at the February 2010 STS-130 mission to the International Space Station. The fourth chapter answers the question why rendezvous was not completely automated on the Gemini, Apollo, and Space Shuttle vehicles.

Goodman, John L.

2011-01-01

29

Rendezvousing at Familiar and Unfamiliar Places  

NASA Astrophysics Data System (ADS)

This paper reports a diary study of rendezvousing as performed by university students. The study compares students' performance when meeting at familiar and unfamiliar rendezvous points. It reports various findings that help to set goals for the development of personal navigation and related services at appropriate levels. For example, when meeting at novel rendezvous points, students: (i) fail to meet as initially agreed more frequently; (ii) report more stress and lost opportunity as a result of rendezvousing problems; (iii) change plan during the rendezvous more often; (iv) communicate more about the rendezvous, particularly using text messaging; (v) attribute rendezvousing problems to lack of geographic and travel information more often, and to additional, spontaneous tasks such as ‘popping to the bank’ less often. Meetings at novel rendezvous points are also more likely to include acquaintances and strangers.

Colbert, Martin

2004-09-01

30

A closer look at tumbling toast  

NASA Astrophysics Data System (ADS)

The study of the mechanics of tumbling toast provides an informative and entertaining project for undergraduates. The relatively recent introduction of software packages to facilitate the analysis of video recordings, and the numerical solution of complex differential equations, makes such a study an attractive candidate for inclusion in an experimental physics course at the undergraduate level. In the study reported here it is found that the experimentally determined free fall angular velocity of a board, tumbling off the edge of a table, can only be predicted at all accurately if slipping is taken into account. The size and shape of the board used in the calculations and in the experiments were roughly the same as that of a piece of toast. In addition, it is found that the board, tumbling from a standard table of height 76 cm, will land butter-side down (neglecting any bounce) for two ranges of overhang (?0). ?0 is defined as the initial distance from the table edge to a vertical line drawn through the center of mass when the board is horizontal. For our board (length 10.2 cm) the approximate ranges of overhang are 0-0.8 and 2.7-5.1 cm. The importance of the 0-0.8 cm (only 2% of all possible overhangs for which tumbling is possible) favoring a butter-side down landing should not be underestimated when pondering the widely held belief that toast, tumbling from a table, usually falls butter-side down.

Bacon, M. E.; Heald, George; James, Matt

2001-01-01

31

TRAC based sensing for autonomous rendezvous  

NASA Technical Reports Server (NTRS)

The Targeting Reflective Alignment Concept (TRAC) sensor is to be used in an effort to support an Autonomous Rendezvous and Docking (AR&D) flight experiment. The TRAC sensor uses a fixed-focus, fixed-iris CCD camera and a target that is a combination of active and passive components. The system experiment is anticipated to fly in 1994 using two Commercial Experiment Transporters (COMET's). The requirements for the sensor are: bearing error less than or equal to 0.075 deg; bearing error rate less than 0.3 deg/sec; attitude error less than 0.5 deg.; and attitude rate error less than 2.0 deg/sec. The range requirement depends on the range and the range rate of the vehicle. The active component of the target is several 'kilo-bright' LED's that can emit 2500 millicandela with 40 milliwatts of input power. Flashing the lights in a known pattern eliminates background illumination. The system should be able to rendezvous from 300 meters all the way to capture. A question that arose during the presentation: What is the life time of the LED's and their sensitivity to radiation? The LED's should be manufactured to Military Specifications, coated with silicon dioxide, and all other space qualified precautions should be taken. The LED's will not be on all the time so they should easily last the two-year mission.

Everett, Louis J.; Monford, Leo

1991-01-01

32

Observing Young Children's Rough-and-Tumble Play  

ERIC Educational Resources Information Center

This research investigated the rough-and-tumble play of 17 five-year-old children in two early childhood settings. The study resulted in an increased understanding of the forms of rough-and-tumble play displayed by young children. This study demonstrates that both boys and girls are engaged in a variety of rough-and-tumble play behaviours.…

Tannock, Michelle

2011-01-01

33

Automated rendezvous and docking with video imagery  

NASA Technical Reports Server (NTRS)

For rendezvous and docking, assessing and tracking relative orientation is necessary within a minimum approach distance. Special target light patterns have previously been considered for use with video sensors for ease of determining relative orientation. A generalization of those approaches is addressed. At certain ranges, the entire structure of the target vehicle constitutes an acceptable target; at closer ranges, substructures will suffice. Acting on the same principle as the human intelligence, these structures can be compared with a memory model to assess the relative orientation and range. Models for comparison are constructed from a CAD facet model and current imagery. This approach requires fast image handling, projection, and comparison techniques which rely on rapidly developing parallel processing technology. Relative orientation and range assessment consists of successful comparison of the perceived target aspect with a known aspect. Generating a known projection from a model within required times, say subsecond times, is only now approaching feasibility. With this capability, rates of comparison used by the human brain can be approached and arbitrary known structures can be compared in reasonable times. Future space programs will have access to powerful computation devices which far exceed even this capability. For example, the possibility will exist to assess unknown structures and then control rendezvous and docking, all at very fast rates. The first step which has the current utility, namely applying this to known structures, is taken.

Rodgers, Mike; Kennedy, Larry Z.

1991-01-01

34

Tumbling For Seed Cleaning and Conditioning1  

Microsoft Academic Search

Small rock tumblers can be used to clean and condition seeds both in an aqueous and a dry mode. During the process, grit and gravel remove fruit pulp and abrade seed coats. Wet tumbling of seed aids imbibition, leaches water-soluble germination inhibitors, and may partially substitute for cold stratification for some shrub seed lots.

David Dreesen

35

Hydra Rendezvous and Docking Sensor  

NASA Technical Reports Server (NTRS)

The U.S. technology to support a CEV AR&D activity is mature and was developed by NASA and supporting industry during an extensive research and development program conducted during the 1990's and early 2000 time frame at the Marshall Space Flight Center. Development and demonstration of a rendezvous/docking sensor was identified early in the AR&D Program as the critical enabling technology that allows automated proxinity operations and docking. A first generation rendezvous/docking sensor, the Video Guidance Sensor (VGS) was developed and successfully flown on STS 87 and again on STS 95, proving the concept of a video-based sensor. Advances in both video and signal processing technologies and the lessons learned from the two successful flight experiments provided a baseline for the development of a new generation of video based rendezvous/docking sensor. The Advanced Video Guidance Sensor (AVGS) has greatly increased performance and additional capability for longer-range operation. A Demonstration Automatic Rendezvous Technology (DART) flight experiment was flown in April 2005 using AVGS as the primary proximity operations sensor. Because of the absence of a docking mechanism on the target satellite, this mission did not demonstrate the ability of the sensor to coltrold ocking. Mission results indicate that the rendezvous sensor operated successfully in "spot mode" (2 km acquisition of the target, bearing data only) but was never commanded to "acquire and track" the docking target. Parts obsolescence issues prevent the construction of current design AVGS units to support the NASA Exploration initiative. This flight proven AR&D technology is being modularized and upgraded with additional capabilities through the Hydra project at the Marshall Space Flight Center. Hydra brings a unique engineering approach and sensor architecture to the table, to solve the continuing issues of parts obsolescence and multiple sensor integration. This paper presents an approach to sensor hardware trades, to address the needs of future vehicles that may rendezvous and dock with the International Space Station (ISS). It will also discuss approaches for upgrading AVGS to address parts obsolescence, and concepts for modularizing the sensor to provide configuration flexibility for multiple vehicle applications. Options for complementary sensors to be integrated into the multi-head Hydra system will also be presented. Complementary sensor options include ULTOR, a digital image correlator system that could provide relative six-degree-of-freedom information independently from AVGS, and time-of-flight sensors, which determine the range between vehicles by timing pulses that travel from the sensor to the target and back. Common targets and integrated targets, suitable for use with the multi-sensor options in Hydra, will also be addressed.

Roe, Fred; Carrington, Connie

2007-01-01

36

Tumble-mix anaerobic digestion of dry beef manure  

SciTech Connect

Anaerobic digestion of beef manure at an influent total solids concentration of 26% was demonstrated using an innovative tumble-mix fermenter. At an organic loading rate of 4.7 kg VS m-/sup 3/ d-/sup 1/ and a 23% VS influent concentration, a 54% volatile solids reduction was achieved. The average biogas production was 1.37 m/sup 3/ m-/sup 3/ d-/sup 1/ with a gas quality of 54% CH/sub 4/.

Kottwitz, D.; Schulte, D.D.

1982-12-01

37

STS-134 Re-Rendezvous Design History  

NASA Technical Reports Server (NTRS)

In preparation to provide the capability for the Orion spacecraft to rendezvous with the International Space Station (ISS), a new suite of relative navigation sensors are in development and will be tested on one of the final Space Shuttle missions to ISS. The National Aeronautics and Space Administration (NASA) commissioned a flight test of prototypes of the instruments on STS-134, in order to test their performance in the space environment during the nominal rendezvous and docking, as well as a re-rendezvous dedicated to testing the prototype sensors following the undocking of the Space Shuttle Orbiter at the end of the mission. Unlike the initial rendezvous and docking, the re-rendezvous profile would replicate the newly designed Orion coelliptic approach trajectory, something never before attempted with the Shuttle Orbiter. Therefore, there were a number of new parameters that needed to be conceived of, designed, and tested for this re-rendezvous to make the flight test successful. And all of this work had to be integrated with the normal operations of the ISS and Shuttle and had to conform to the constraints of the mission and vehicles. The result of this work is a separation and re-rendezvous trajectory design that will prove not only the design of the relative navigation sensors for the Orion vehicle, but also will serve as a proof of concept for the Orion rendezvous trajectory itself. This document presents the analysis and decision making process involved in attaining the final STS-134 re-rendezvous design.

Stuit, Timothy D.

2011-01-01

38

Comet rendezvous - The next step  

NASA Technical Reports Server (NTRS)

Features of a proposed NASA-West Germany Comet Rendezvous Asteroid Flyby mission (CRAF) are summarized. The spacecraft would carry an imaging system, visual and IR mapping spectrometers, an IR radiometer, an instrumented lander probe, ion mass, neutral-gas, secondary-ion mass, superthermal-ion and retarding potential ion mass spectrometers, etc. The spacecraft would fly alongside the nucleus, hover near it, and circle it. The earliest potential encounter would be with Comet Tempel 2 in October 1996, followed by a flyby of the asteroid 46 Hestia. The science goals of the mission are explored, mainly with reference to unanswered questions remaining after the Halley missions.

Neugebauer, Marcia

1987-01-01

39

NASA MSFC hardware in the loop simulations of automatic rendezvous and capture systems  

NASA Technical Reports Server (NTRS)

Two complementary hardware-in-the-loop simulation facilities for automatic rendezvous and capture systems at MSFC are described. One, the Flight Robotics Laboratory, uses an 8 DOF overhead manipulator with a work volume of 160 by 40 by 23 feet to evaluate automatic rendezvous algorithms and range/rate sensing systems. The other, the Space Station/Station Operations Mechanism Test Bed, uses a 6 DOF hydraulic table to perform docking and berthing dynamics simulations.

Tobbe, Patrick A.; Naumann, Charles B.; Sutton, William; Bryan, Thomas C.

1991-01-01

40

Onboard navigation rendezvous expert system  

NASA Technical Reports Server (NTRS)

The Onboard Navigation rendezvous expert system is designed to aid the ground flight controller in monitoring the shuttle onboard navigation system. The system is designed to keep track of the navigation sensors and relative state vectors. In addition, the system also keeps an event log and fills out forms usually handled by the flight controller. This expert system is one of the few rendezvous specific systems being developed for the Mission Control Center. The expert system has been in development for six years. Through these years the system has seen hardware, software, and personnel changes. Initial development was done by the Information Systems Directorate (ISD) and Mission Operations Directorate (MOD) at Johnson Space Center. As of October 1, 1991 the system has been turned over to MOD. The system is completely developed except for some minor adjustments to the user interface. The rule base is in the verification stage with total certification of the system due to be completed by May 1992. Test cases for verification are obtained by saving data used for flight controller integrated simulations. The actual data comes from both the shuttle mission simulator and the Mission Control Center Computer. So far no actual flight data has been available. This paper covers all aspects of the system from the development history to the current hardware, software, and use of the system.

Kocen, Michelle

1991-01-01

41

Terminal guidance and navigation for comet and asteroid rendezvous  

NASA Technical Reports Server (NTRS)

A terminal guidance and navigation scheme developed in earlier work was modified and evaluated for a solar electric propulsion rendezvous mission to comet Encke. The scheme is intended for autonomous, on-board use. The guidance algorithm is based on optimal control theory and minimizes the time integrated square of thrust acceleration. The navigation algorithm employs a modified Kalman filter set in measurement variables. Random sequences were generated to simulate measurement errors, and the evaluation was conducted with detailed numerical computations which include actual motions of spacecraft and comet. The evaluations showed that the scheme attains rendezvous and maintains station after rendezvous within less than 10 km for estimated best measurements and within less than 100 km for estimated worst measurements. The measurements required are angles, range, and range rate. Angles and range appear to be absolutely necessary; range rate is not as strong a measurement type, and further modifications of the filter will allow a scheme that does not require the rate measurements.

Bennett, A. G.; Pitts, R. G.

1975-01-01

42

Particle motion and energy distribution in tumbling ball mills  

Microsoft Academic Search

The charge flow characteristics and the local energy distributions have a profound influence on the comminution behavior in tumbling ball mills. Computer simulation using a particle dynamics method offers a viable approach for investigating the flow and energy distribution characteristics within tumbling particulate media. In particle dynamics method, particulate systems are simulated by tracking particles as they move in response

Anil Misra; Josephine Cheung

1999-01-01

43

Dynamics and control of a tumbling satellite retrieval device  

Microsoft Academic Search

The problem of capturing and despinning a satellite in an uncontrolled three-axis tumble is addressed. The proposed solution is a device which resembles a hollow cage. Thin cylindrical elements are arranged in a regular octahedron, forming a three-dimensional space truss with masses mounted at each corner of the octahedron. The device, which is larger than the tumbling satellite, opens at

Jon Mark Neff

1991-01-01

44

Hubble Space Telescope Servicing Mission 3A Rendezvous Operations  

NASA Technical Reports Server (NTRS)

The Hubble Space Telescope (HST) hardware complement includes six gas bearing, pulse rebalanced rate integrating gyros, any three of which are sufficient to conduct the science mission. After the loss of three gyros between April 1997 and April 1999 due to a known corrosion mechanism, NASA decided to split the third HST servicing mission into SM3A, accelerated to October 1999, and SM3B, scheduled for November 2001. SM3A was developed as a quick turnaround 'Launch on Need' mission to replace all six gyros. Loss of a fourth gyro in November 1999 caused HST to enter Zero Gyro Sunpoint (ZGSP) safemode, which uses sun sensors and magnetometers for attitude determination and momentum bias to maintain attitude stability during orbit night. Several instances of large attitude excursions during orbit night were observed, but ZGSP performance was adequate to provide power-positive sun pointing and to support low gain antenna communications. Body rates in ZGSP were estimated to exceed the nominal 0.1 deg/sec rendezvous limit, so rendezvous operations were restructured to utilize coarse, limited life, Retrieval Mode Gyros (RMGs) under Hardware Sunpoint (HWSP) safemode. Contingency procedures were developed to conduct the rendezvous in ZGSP in the event of RMGA or HWSP computer failure. Space Shuttle Mission STS-103 launched on December 19, 1999 after a series of weather and Shuttle-related delays. After successful rendezvous and grapple under HWSP/RMGA, the crew changed out all six gyros. Following deploy and systems checkout, HST returned to full science operations.

Lee, S.; Anandakrishnan, S.; Connor, C.; Moy, E.; Smith, D.; Myslinski, M.; Markley, L.; Vernacchio, A.

2001-01-01

45

The Comet Rendezvous Asteroid Flyby project  

NASA Technical Reports Server (NTRS)

The Comet Rendezvous Asteroid Flyby (CRAF) spacecraft will be provided by the first Mariner Mark II (MMII). The MMII is a modular spacecraft which can be inexpensively reconfigured for different missions beyond the inner solar system. The rationale for a comet rendezvous mission are discussed, taking into account the probability that comets alone retain evidence of the chemical and physical conditions under which all solar system bodies were formed. A description of the rationale for the study of asteroids on the Comet Rendezvous Asteroid Flyby Mission is also presented. On its way to the rendezvous with a comet, the spacecraft will fly by one or more asteroids. It is assumed that the target asteroids will include moderately large main-belt objects several tens to perhaps 100 kilometers in diameter. Attention is also given to mission details, the spacecraft system, and the missions operations system.

Draper, R. F.

1985-01-01

46

Tumbling, an Interactive Way to Move Forward  

NSDL National Science Digital Library

The migration of Drosophila border cells has become a powerful model with which to genetically identify guidance cues that control the directed migration of a group of interconnected cells. During oogenesis, border cells delaminate from an epithelial layer and move collectively toward the oocyte. In vivo observation has been added to the impressive experimental toolkit available to study border cell migration. These studies reveal two previously unknown migratory behaviors: one in which cells within the border cell cluster constantly change their position, and another called "tumbling," by which the entire border cell cluster rotates forward. Unexpectedly, the same receptor tyrosine kinases control these different modes of migration through separate downstream pathways. An early mode is mediated by the actin regulatory proteins ELMO and Mbc and resembles cellular polarization during individual cell migration; whereas during a later phase, communication between cells, facilitated by mitogen-activated protein kinase and phospholipase C–γ, organizes the polarity of the entire cluster.

Hiroko Sano (New York University School of Medicine;Howard Hughes Medical Institute and the Kimmel Center for Biology and Medicine of the Skirball Institute REV); Sara Ricardo (New York University School of Medicine;Howard Hughes Medical Institute and the Kimmel Center for Biology and Medicine of the Skirball Institute REV); Ruth Lehmann (New York University School of Medicine;Howard Hughes Medical Institute and the Kimmel Center for Biology and Medicine of the Skirball Institute REV)

2007-11-13

47

Failed escape: solid surfaces prevent tumbling of Escherichia coli.  

PubMed

Understanding how bacteria move close to surfaces is crucial for a broad range of microbial processes including biofilm formation, bacterial dispersion, and pathogenic infections. We used digital holographic microscopy to capture a large number (>10(3)) of three-dimensional Escherichia coli trajectories near and far from a surface. We found that within 20???m from a surface tumbles are suppressed by 50% and reorientations are largely confined to surface-parallel directions, preventing escape of bacteria from the near-surface region. A hydrodynamic model indicates that the tumble suppression is likely due to a surface-induced reduction in the hydrodynamic force responsible for the flagellar unbundling that causes tumbling. These findings imply that tumbling does not provide an effective means to escape trapping near surfaces. PMID:25148353

Molaei, Mehdi; Barry, Michael; Stocker, Roman; Sheng, Jian

2014-08-01

48

Development of an autonomous video rendezvous and docking system, phase 3  

NASA Technical Reports Server (NTRS)

Field-of-view limitations proved troublesome. Higher resolution was required. Side thrusters were too weak. The strategy logic was improved and the Kalman filter was augmented to estimate target attitude and tumble rate. Two separate filters were used. The new filter estimates target attitude and angular momentum. The Newton-Raphson iteration improves image interpretation.

Tietz, J. C.

1984-01-01

49

Rendezvous radar for the orbital maneuvering vehicle  

NASA Technical Reports Server (NTRS)

The Rendezvous Radar Set (RRS) was designed at Motorola's Strategic Electronics Division in Chandler, Arizona, to be a key subsystem aboard NASA's Orbital Maneuvering Vehicle (OMV). The unmanned OMV, which was under development at TRW's Federal Systems Division in Redondo Beach, California, was designed to supplement the Shuttle's satellite delivery, retrieval, and maneuvering activities. The RRS was to be used to locate and then provide the OMV with vectoring information to the target satellite (or Shuttle or Space Station) to aid the OMV in making a minimum fuel consumption approach and rendezvous. The OMV development program was halted by NASA in 1990 just as parts were being ordered for the RRS engineering model. The paper presented describes the RRS design and then discusses new technologies, either under development or planned for development at Motorola, that can be applied to radar or alternative sensor solutions for the Automated Rendezvous and Capture problem.

Locke, John W.; Olds, Keith A.; Quaid, Thomas

1991-01-01

50

Multiple exposure of Rendezvous Docking Simulator  

NASA Technical Reports Server (NTRS)

Multiple exposure of Rendezvous Docking Simulator. Francis B. Smith, described the simmulator as follows: 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.'

1964-01-01

51

A frequency rendezvous approach for decentralized dynamic spectrum access networks  

Microsoft Academic Search

In this paper, we propose a transmission frequency rendezvous approach for secondary users deployed in decentralized dynamic spectrum access networks. Frequency rendezvous is a critical step in bootstrapping a wireless network that does not possess centralized control. Current techniques for enabling frequency rendezvous in decentralized dynamic spectrum access networks either require pre-existing infrastructure or use one of several simplifying assumptions

Di Pu; Alexander M. Wyglinski; Mike McLernon

2009-01-01

52

Study of a comet rendezvous mission. Volume 2: Appendices  

NASA Technical Reports Server (NTRS)

Appendices to the comet Encke rendezvous mission consider relative positions of comet, earth and sun; viewing condition for Encke; detection of Taurid meteor streams; ephemeris of comet Encke; microwave and optical techniques in rendezvous mission; approach instruments; electrostatic equilibrium of ion engine spacecraft; comet flyby data for rendezvous spacecraft assembly; observations of P/Encke extracted from a compilation; and summary of technical innovations.

1972-01-01

53

Trigger Angle Targeting for Orbital Rendezvous  

NASA Astrophysics Data System (ADS)

Orbital rendezvous missions often have a co-elliptic approach phase where a chaser vehicle approaches an object with a near-constant relative altitude and relative velocity. A well known orbital rendezvous technique is to trigger the Terminal Phase Initiation (TPI) maneuver when the apparent elevation of the target reaches some nominal angle. The best elevation trigger angle on which to initiate the final transfer maneuver must balance favorable performance characteristics and desirable operational simplicity. A detailed analysis is given deriving the best trigger angles and showing how these results correlate to past missions and how they could potentially influence future ones.

Woffinden, David C.; Ben Rose, M.; Geller, David K.

2008-12-01

54

Onboard rendezvous navigation for the Space Shuttle  

NASA Technical Reports Server (NTRS)

The onboard rendezvous navigation software for Shuttle flight 41-C are described. Particular attention is given to the inputs, models, and outputs of the software. The performance of the rendezvous navigation system is compared to predicted performance profiles in connection with the relative vehicle geometry, as well as the location of the navigation sensor tracking arcs. The methods used to process navigational sensor measurements in order to update the state vector are also summarized. A table listing the sources of maneuver targeting errors is provided.

Wylie, A. D.; Devezin, H. G.

1985-01-01

55

The real-time operations of the Space Shuttle Orbiter during rendezvous and proximity operations  

NASA Technical Reports Server (NTRS)

The Space Shuttle Orbiter is the only U.S. spacecraft in operation today that routinely performs an orbital rendezvous with another spacecraft. The trajectory planning and training of both flight crews and ground operations personnel required to achieve a 100 percent success rate is considerable. The preflight planning and training can be reduced through very simple design considerations of a new space vehicle.

Dougherty, Andrew; Meyer, Chris

1991-01-01

56

Designing the STS-134 Re-Rendezvous: A Preparation for Future Crewed Rendezvous Missions  

NASA Technical Reports Server (NTRS)

In preparation to provide the capability for the Orion spacecraft, also known as the Multi-Purpose Crew Vehicle (MPCV), to rendezvous with the International Space Station (ISS) and future spacecraft, a new suite of relative navigation sensors are in development and were tested on one of the final Space Shuttle missions to ISS. The National Aeronautics and Space Administration (NASA) commissioned a flight test of prototypes of the Orion relative navigation sensors on STS-134, in order to test their performance in the space environment during the nominal rendezvous and docking, as well as a re-rendezvous dedicated to testing the prototype sensors following the undocking of the Space Shuttle orbiter at the end of the mission. Unlike the rendezvous and docking at the beginning of the mission, the re-rendezvous profile replicates the newly designed Orion coelliptic approach trajectory, something never before attempted with the shuttle orbiter. Therefore, there were a number of new parameters that needed to be conceived of, designed, and tested for this rerendezvous to make the flight test successful. Additionally, all of this work had to be integrated with the normal operations of the ISS and shuttle and had to conform to the constraints of the mission and vehicles. The result of this work is a separation and rerendezvous trajectory design that would not only prove the design of the relative navigation sensors for the Orion vehicle, but also would serve as a proof of concept for the Orion rendezvous trajectory itself. This document presents the analysis and decision making process involved in attaining the final STS-134 re-rendezvous design.

Stuit, Timothy D.

2011-01-01

57

Tracking techniques for space shuttle rendezvous  

NASA Technical Reports Server (NTRS)

The space shuttle rendezvous radar has a requirement to track cooperative and non-cooperative targets. For this reason the Lunar Module (LM) Rendezvous Radar was modified to incorporate the capability of tracking a non-cooperative target. The modifications are discussed. All modifications except those relating to frequency diversity were completed, and system tests were performed to confirm proper performance in the non-cooperative mode. Frequency diversity was added to the radar and to the special test equipment, and then system tests were performed. This last set of tests included re-running the tests of the non-cooperative mode without frequency diversity, followed by tests with frequency diversity and tests of operation in the original cooperative mode.

1975-01-01

58

Laser space rendezvous and docking tradeoff  

NASA Technical Reports Server (NTRS)

A spaceborne laser radar (LADAR) was configured to meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit. The LADAR, configurated using existing pulsed CO2 laser technology and a 1980 system technology baseline, is well suited for the envisioned space tug missions. The performance of a family of candidate LADARS was analyzed. Tradeoff studies as a function of size, weight, and power consumption were carried out for maximum ranges of 50, 100, 200, and 300 nautical miles. The investigation supports the original contention that a rendezvous and docking LADAR can be constructed to offer a cost effective and reliable solution to the envisioned space missions. In fact, the CO2 ladar system offers distinct advantages over other candidate systems.

Adelman, S.; Levinson, S.; Raber, P.; Weindling, F.

1974-01-01

59

Determination of tailless aircraft tumbling and stability characteristics through computational fluid dynamics  

Microsoft Academic Search

Tailless aircraft configurations such as flying wings are susceptible to tumbling. Tumbling involves an autorotative pitching motion primarily about an axis parallel to the aircraft's lateral axis combined with planar translation. Tumbling is the suspected cause of a tailless aircraft (Northrop YB-49) crash in the late 1940s and is a potential problem for future flying wing and blended wing body

Syta Saephan

2006-01-01

60

Lunar Ascent and Rendezvous Trajectory Design  

NASA Technical Reports Server (NTRS)

The Lunar Lander Ascent Module (LLAM) will leave the lunar surface and actively rendezvous in lunar orbit with the Crew Exploration Vehicle (CEV). For initial LLAM vehicle sizing efforts, a nominal trajectory, along with required delta-V and a few key sensitivities, is very useful. A nominal lunar ascent and rendezvous trajectory is shown, along with rationale and discussion of the trajectory shaping. Also included are ascent delta-V sensitivities to changes in target orbit and design thrust-to-weight of the vehicle. A sample launch window for a particular launch site has been completed and is included. The launch window shows that budgeting enough delta-V for two missed launch opportunities may be reasonable. A comparison between yaw steering and on-orbit plane change maneuvers is included. The comparison shows that for large plane changes, which are potentially necessary for an anytime return from mid-latitude locations, an on-orbit maneuver is much more efficient than ascent yaw steering. For a planned return, small amounts of yaw steering may be necessary during ascent and must be accounted for in the ascent delta-V budget. The delta-V cost of ascent yaw steering is shown, along with sensitivity to launch site latitude. Some discussion of off-nominal scenarios is also included. In particular, in the case of a failed Powered Descent Initiation burn, the requirements for subsequent rendezvous with the Orion vehicle are outlined.

Sostaric, Ronald R.; Merriam, Robert S.

2008-01-01

61

Orion Handling Qualities During ISS Rendezvous and Docking  

NASA Technical Reports Server (NTRS)

The Orion spacecraft was designed to rendezvous with multiple vehicles in low earth orbit (LEO) and beyond. To perform the required rendezvous and docking task, Orion must provide enough control authority to perform coarse translational maneuvers while maintaining precision to perform the delicate docking corrections. While Orion has autonomous docking capabilities, it is expected that final approach and docking operations with the International Space Station (ISS) will initially be performed in a manual mode. A series of evaluations was conducted by NASA and Lockheed Martin at the Johnson Space Center to determine the handling qualities (HQ) of the Orion spacecraft during different docking and rendezvous conditions using the Cooper-Harper scale. This paper will address the specifics of the handling qualities methodology, vehicle configuration, scenarios flown, data collection tools, and subject ratings and comments. The initial Orion HQ assessment examined Orion docking to the ISS. This scenario demonstrates the Translational Hand Controller (THC) handling qualities of Orion. During this initial assessment, two different scenarios were evaluated. The first was a nominal docking approach to a stable ISS, with Orion initializing with relative position dispersions and a closing rate of approximately 0.1 ft/sec. The second docking scenario was identical to the first, except the attitude motion of the ISS was modeled to simulate a stress case ( 1 degree deadband per axis and 0.01 deg/sec rate deadband per axis). For both scenarios, subjects started each run on final approach at a docking port-to-port range of 20 ft. Subjects used the THC in pulse mode with cues from the docking camera image, window views, and range and range rate data displayed on the Orion display units. As in the actual design, the attitude of the Orion vehicle was held by the automated flight control system at 0.5 degree deadband per axis. Several error sources were modeled including Reaction Control System (RCS) jet angular and position misalignment, RCS thrust magnitude uncertainty, RCS jet force direction uncertainty due to self plume impingement, and Orion center of mass uncertainty.

Hart, Jeremy J.; Stephens, J. P.; Spehar, P.; Bilimoria, K.; Foster, C.; Gonzalex, R.; Sullivan, K.; Jackson, B.; Brazzel, J.; Hart, J.

2011-01-01

62

Rough-and-Tumble Play on the Elementary School Playground.  

ERIC Educational Resources Information Center

Discusses rough-and-tumble (R&T) play and misconceptions about its role in the development of young children. Contrasts R&T with aggressive behaviors. Discusses the educational benefits of R&T and offers recommendations for incorporating it into young children's curricula. (Author/RWB)

Pellegrini, A. D.; Perlmutter, Jane C.

1988-01-01

63

Tumbling mill steel media abrasion wear test development  

Microsoft Academic Search

The goal of this paper is to propose, build and test an abrasion apparatus that will allow the investigation of tumbling mill steel media abrasive friction and wear as a function of the energies\\/forces acting in abrasion in a given mill. The following development is based on the possibility of estimating energy\\/force spectra in abrasion by using a discrete element

Peter Radziszewski; Rena Varadi; Tapiwa Chenje; Lena Santella; Anthony Sciannamblo

2005-01-01

64

Orbit determination of the Comet Rendezvous/Asteroid Flyby mission - Post-rendezvous phases  

NASA Technical Reports Server (NTRS)

Orbit determination during the post-rendezvous phases of the Comet Rendezvous/Asteroid Flyby mission is described. The orbit determination process is discussed, with emphasis placed on optical imaging of landmarks and Doppler tracking. Rotational dynamics are introduced for the cometary nucleus. State estimation errors are given for spacecraft trajectory prediction and cometary nucleus attitude prediction. Estimation errors are also given for parameters that describe the cometary nucleus such as moments of inertia and gravity harmonics. The orbit determination performance in support of science observations while in orbit about the nucleus is described.

Miller, James K.; Wood, Lincoln J.; Weeks, Connie J.

1989-01-01

65

Red blood cells and other non-spherical capsules in shear flow: oscillatory dynamics and the tank-treading-to-tumbling transition  

E-print Network

We consider the motion of red blood cells and other non-spherical microcapsules dilutely suspended in a simple shear flow. Our analysis indicates that depending on the viscosity, membrane elasticity, geometry and shear rate, the particle exhibits either tumbling, tank-treading of the membrane about the viscous interior with periodic oscillations of the orientation angle, or intermittent behavior in which the two modes occur alternately. For red blood cells, we compute the complete phase diagram and identify a novel tank-treading-to-tumbling transition at low shear rates. Observations of such motions coupled with our theoretical framework may provide a sensitive means of assessing capsule properties.

J. M. Skotheim; T. W. Secomb

2006-05-26

66

Radar Performance Improvement. Angle Tracking Modification to Fire Control Radar System for Space Shuttle Rendezvous  

NASA Technical Reports Server (NTRS)

The AN/APQ-153 fire control radar modified to provide angle tracking was evaluated for improved performance. The frequency agile modifications are discussed along with the range-rate improvement modifications, and the radar to computer interface. A parametric design and comparison of noncoherent and coherent radar systems are presented. It is shown that the shuttle rendezvous range and range-rate requirements can be made by a Ku-Band noncoherent pulse radar.

Little, G. R.

1976-01-01

67

Multiple Radios for Effective Rendezvous in Cognitive Radio Networks  

E-print Network

Multiple Radios for Effective Rendezvous in Cognitive Radio Networks Lu Yu1 , Hai Liu1 , Yiu in cognitive radio networks (CRNs) for establishing a communication link on a commonly-available channel, we investigate the rendezvous problem in CRNs where cognitive users are equipped with multiple radios

Chu, Xiaowen

68

Powered Safe Abort for Autonomous Rendezvous of Spacecraft  

E-print Network

Powered Safe Abort for Autonomous Rendezvous of Spacecraft Louis Breger and Jonathan P. How MIT-optimized rendezvous trajectories. These trajectories guarantee the existence of known powered abort trajectories the existence of known active safe abort trajectories for a large class of possible spacecraft anomalies

How, Jonathan P.

69

Let's Rendezvous: Application of Location-Aware Computing  

E-print Network

technology and location-aware devices to aid in the act of rendezvousing. Most technologies (cell-phones. The exciting aspect of our rendezvousing project is our exploration of the social impact location-aware devices navigation are vast and we hope to make some initial observations concerning its social impact. In addition

Toronto, University of

70

Automated rendezvous and capture demonstration study  

NASA Technical Reports Server (NTRS)

This study was instituted to assist NASA and MSFC in the development of ground and flight options to demonstrate the capability of Automated Rendezvous and Capture (AR&C). Study goals placed emphasis on low cost approaches and the need to be responsive to newly developing programs and studies such as Space Station Freedom and the Cargo Transfer Vehicle. This study provides an assessment of vehicle options and AR&C requirements to assist in the meaningful development of an AR&C capability. This report documents study activities performed at Applied Research, Inc. (ARI) between 1 Apr. 1992 and May 1993.

1993-01-01

71

Autonomous Rendezvous and Docking Conference, volume 2  

NASA Technical Reports Server (NTRS)

Autonomous Rendezvous and Docking (ARD) will be a requirement for future space programs. Clear examples include satellite servicing, repair, recovery, and reboost in the near term, and the longer range lunar and planetary exploration programs. ARD will permit more aggressive unmanned space activities, while providing a valuable operational capability for manned missions. The purpose of the conference is to identify the technologies required for an on-orbit demonstration of ARD, assess the maturity of those technologies, and provide the necessary insight for a quality assessment of programmatic management, technical, schedule, and cost risks.

1990-01-01

72

Rendezvous radar for the orbital maneuvering vehicle  

NASA Technical Reports Server (NTRS)

This paper describes the development of the Rendezvous Radar Set (RRS) for the Orbital Maneuvering Vehicle (OMV) for the National Aeronautics and Space Administration (NASA). The RRS was to be used to locate, and then provide vectoring information to, target satellites (or Shuttle or Space Station) to aid the OMV in making a minimum-fuel-consumption approach and rendezvous. The RRS design is that of an X-Band, all solid-state, monopulse tracking, frequency hopping, pulse-Doppler radar system. The development of the radar was terminated when the OMV prime contract to TRW was terminated by NASA. At the time of the termination, the development was in the circuit design stage. The system design was virtually completed, the PDR had been held. The RRS design was based on Motorola's experiences, both in the design and production of radar systems for the US Army and in the design and production of hi-rel communications systems for NASA space programs. Experience in these fields was combined with the latest digital signal processor and micro-processor technology to design a light-weight, low-power, spaceborne radar. The antenna and antenna positioner (gimbals) technology developed for the RRS is now being used in the satellite-to-satellite communication link design for Motorola's Iridium telecommunications system.

Locke, John W.; Olds, Keith; Parks, Howard

1991-01-01

73

The comet rendezvous asteroid flyby mission  

NASA Technical Reports Server (NTRS)

The Comet Rendezvous Asteroid Flyby (CRAF) mission is designed to answer the many questions raised by the Halley missions by exploring a cometary nucleus in detail, following it around its orbit and studying its changing activity as it moves closer to and then away from the Sun. In addition, on its way to rendezvous with the comet, CRAF will fly by a large, primitive class main belt asteroid and will return valuable data for comparison with the comet results. The selected asteroid is 449 Hamburga with a diameter of 88 km and a surface composition of carbonaceous chondrite meteorites. The expected flyby date is January, 1998. The CRAF spacecraft will continue to make measurements in orbit around the cometary nucleus as they both move closer to the Sun, until the dust and gas hazard becomes unsafe. At that point the spacecraft will move in and out between 50 and 2,500 kilometers to study the inner coma and the cometary ionosphere, and to collect dust and gas samples for onboard analysis. Following perihelion, the spacecraft will make a 50,000 km excursion down the comet's tail, further investigating the solar wind interaction with the cometary atmosphere. The spacecraft will return to the vicinity of the nucleus about four months after perihelion to observe the changes that have taken place. If the spacecraft remains healthy and adequate fuel is still onboard, an extended mission to follow the comet nucleus out to aphelion is anticipated.

Morrison, David; Neugebauer, Marcia; Weissman, Paul R.

1989-01-01

74

Statistical Mechanics of Interacting Run-and-Tumble Bacteria  

E-print Network

We consider self-propelled particles undergoing run-and-tumble dynamics (as exhibited by E. coli) in one dimension. Building on previous analyses at drift-diffusion level for the one-particle density, we add both interactions and noise, enabling discussion of domain formation by "self-trapping", and other collective phenomena. Mapping onto detailed-balance systems is possible in certain cases.

J. Tailleur; M. E. Cates

2008-03-07

75

Rough?and?tumble play and social problem solving flexibility  

Microsoft Academic Search

There were three goals in this study: To determine the relation between boys’ temperament and rough?and?tumble (R&T) play; to determine the group composition of R&T, games, and other forms of reciprocal social interaction; and to determine the extent to which the vigor and flexibility components of R&T are related to social affiliation and social problem solving flexibility. Thirteen sociometrically defined

A. D. Pellegrini

1992-01-01

76

Open Field Phase Measurement Telemeter For Orbital Rendez-Vous  

NASA Astrophysics Data System (ADS)

For about four years, collaborating with its industrial and scientific partners, CNES has studied the different types of optical sensors that could help to fulfil an impactless rendez-vous and docking mission between two spatial vehicles moving on a low orbit around the Earth. As a part of that activities, a study realized by Sercel and CNES resulted in the definition of a phase measurement rangefinder able to measure distances from 2 to 500 meters with an accuracy varying from 20 millimeters to 40 millimeters at a rate of 1 Hz. The range and the field of view (+5°) of that instrument together with specific constraints due to spatial environment lead to choose high power (100 mW) current modulated continuous wave laser diode as lightning source for this application. As a matter of fact, the target satellite must keep passive during the mission. Furthermore, the sensor must work in open field to avoid the use of mechanical scanning systems and must be able to deliver a correct information even if the sun is in its field of view so that the rendez-vous scenario is not constrainted. Last, semi-conductor technologies have been preferred because their spatialisation seems to be simpler. Yet, a speckle phenomenon due to the multimode optical fibre onto which the laser diode is connected appears in the field of view. That phenomenon, associated to the dynamic behaviour of the component (spectral drift versus current intensity) prevents the sensor from delivering an homogeneous answer in different points of the field. The phenomenon has been analysed and a solution implying an adapted modulation for the laser diode is proposed. The global sensor principle is described.

Faup, Michel; Hullein, Francois

1989-01-01

77

Demonstration of autonomous rendezvous technology (DART) project summary  

NASA Astrophysics Data System (ADS)

Since the 1960s, NASA has performed numerous rendezvous and docking missions. The common element of all US rendezvous and docking is that the spacecraft has always been piloted by astronauts. Only the Russian Space Program has developed and demonstrated an autonomous capability. The Demonstration of Autonomous Rendezvous Technology (DART) project currently funded under NASA's SPace Launch Initiative (SLI) Cycle I , provides a key step in establishing an autonomous rendezvous capaibility for the United States. The Objective of the DART mission is to demonstrate, in space, the hardware and software necessary for autonomous rendezvous. Orbital Sciences Corporation intends to integrate an Advanced Video Guidance Sensor and Autonomous Rendezvous and Proximity Operations algorithms into a Pegasus upper stage in order to demonstrate the capability to autonomously rendezvous with a target currently in orbit. The DART mission will occur in April 2004. The launch site will be Vandenberg AFB and the launch vehicle will be a Pegasus XL equipped with a Hydrazine Auxiliary Propulsion System 4th Stage. All mission objectives will be completed within a 24 hour period. The paper provides a summary of mission objectives, mission overview and a discussion on the design features of the chase and target vehicles.

Rumford, Timothy E.

2003-08-01

78

Elementary-School Children's Rough-and-Tumble Play and Social Competence  

Microsoft Academic Search

The intent of this study was to describe relations between elementary-school children's rough-and-tumble play and their social competence. Elementary-school children (Grades K, 2, and 4) were observed on the school playground during their recess periods. Results suggested that rough-and-tumble play for popular children led to games-with-rules, whereas it led to aggression for rejected children. Furthermore, popular children's rough-and-tumble was positively

A. D. Pellegrini

1988-01-01

79

Concept definition study for recovery of tumbling satellites. Volume 1: Executive summary, study results  

NASA Technical Reports Server (NTRS)

The first assessment is made of the design requirements and conceptual definition of a front end kit to be transported on the currently defined Orbital Maneuvering Vehicle (OMV) and the Space Transportation System Shuttle Orbiter, to conduct remote, teleoperated recovery of disabled and noncontrollable, tumbling satellites. Previous studies did not quantify the dynamic characteristics of a tumbling satellite, nor did they appear to address the full spectrum of Tumbling Satellite Recovery systems requirements. Both of these aspects are investigated with useful results.

Cable, D. A.; Derocher, W. L., Jr.; Cathcart, J. A.; Keeley, M. G.; Madayev, L.; Nguyen, T. K.; Preese, J. R.

1986-01-01

80

Expert system isssues in automated, autonomous space vehicle rendezvous  

NASA Technical Reports Server (NTRS)

The problems involved in automated autonomous rendezvous are briefly reviewed, and the Rendezvous Expert (RENEX) expert system is discussed with reference to its goals, approach used, and knowledge structure and contents. RENEX has been developed to support streamlining operations for the Space Shuttle and Space Station program and to aid definition of mission requirements for the autonomous portions of rendezvous for the Mars Surface Sample Return and Comet Nucleus Sample return unmanned missions. The experience with REMEX to date and recommendations for further development are presented.

Goodwin, Mary Ann; Bochsler, Daniel C.

1987-01-01

81

Automated Rendezvous and Capture in Space: A Technology Assessment  

NASA Technical Reports Server (NTRS)

This paper presents the results of a study to assess the technology of automated rendezvous and capture (AR&C) in space. The outline of the paper is as follows: First, the history of manual and automated rendezvous and capture and rendezvous and dock is presented. Next, the need for AR&C in space is reviewed. In light of these, AR&C systems are proposed that meet NASA's future needs, but can be developed in a reasonable amount of time with a reasonable amount of money. Technology plans for developing these systems are presented; cost and schedule are included.

Polites, Michael E.

1998-01-01

82

Rendezvous requirements and candidate worst case flights from the October 1973 space shuttle traffic model  

NASA Technical Reports Server (NTRS)

Data appearing in the October 1973 space shuttle traffic model were analyzed to determine the rendezvous requirements for the proposed shuttle flights occurring between 1980 and 1991. Four families of flights have been identified, namely, single-payload rendezvous, multiple-payload rendezvous, payload and tug rendezvous, and tug only rendezvous. Charts have been prepared which summarize the respective data. Observations are presented for each of the four flight families, and worst case flights are proposed from each family for further analysis.

Kreiter, T. J.

1974-01-01

83

Pathfinder autonomous rendezvous and docking project  

NASA Technical Reports Server (NTRS)

Capabilities are being developed and demonstrated to support manned and unmanned vehicle operations in lunar and planetary orbits. In this initial phase, primary emphasis is placed on definition of the system requirements for candidate Pathfinder mission applications and correlation of these system-level requirements with specific requirements. The FY-89 activities detailed are best characterized as foundation building. The majority of the efforts were dedicated to assessing the current state of the art, identifying desired elaborations and expansions to this level of development and charting a course that will realize the desired objectives in the future. Efforts are detailed across all work packages in developing those requirements and tools needed to test, refine, and validate basic autonomous rendezvous and docking elements.

Lamkin, Stephen (editor); Mccandless, Wayne (editor)

1990-01-01

84

Ion Drive multi-asteroid rendezvous trajectories  

NASA Technical Reports Server (NTRS)

The general characteristics of multiasteroid rendezvous missions are examined, taking into account a use of an improved solar electric propulsion system, called Ion Drive. The improvements are related to the development of light-weight solar cells, extensions to high thruster power levels with high exhaust velocity, and the attachment of solar concentrators to increase the power available beyond 1.5 AU. Flight times on the order of 500-800 days are generally required. It is assumed that a stay time of about 60 days at each asteroid is adequate. Attention is given to launch and spacecraft parameters, the search technique, and multiasteroid tours involving Ceres and Vesta. It is found that at least four asteroids in the main belt, generally selected from those with known characteristics, may be reached on a single mission with a 100-kg separable probe landed on each one.

Bender, D. F.

1977-01-01

85

Effect of tumbling and RN genotype on sensory perception of cured-smoked pork loin.  

PubMed

Effects of tumbling and RN genotype on sensory perception of cured-smoked loins were studied on loins from 32 crossbred female pigs containing Hampshire blood. Right-side loins were intermittently tumbled during 4 h, whereas left-side loins were left non-tumbled. Tumbled loins were more tender and uniform in cured colour as well as less acidulous in taste compared with non-tumbled loins. Further, the formation of undesirable pores was lower in tumbled loins. Final juiciness tended to be higher and meat taste intensity lower in tumbled loins, whereas initial juiciness did not differ. There were no significant interactions between tumbling and RN genotype for sensory attributes. RN(-) carriers (RN(-)/rn(+)) were more acidulous in taste, had more pronounced meat taste and were saltier than non-carriers (rn(+) /rn(+)). Moreover, they tended to have higher initial juiciness and more undesirable pores, and be less homogeneous in cured pink colour. No differences in consumer preference between the four treatments were detected in the ranking test, but most persons ranked non-tumbled loins highest regarding overall liking. Instrumental tenderness measurements agreed well with sensory tenderness scores. PMID:22063150

Hullberg, Anja; Johansson, Lisbeth; Lundström, Kerstin

2005-04-01

86

Navigation for Rendezvous and Orbit Missions to Small Solar-System Bodies  

NASA Technical Reports Server (NTRS)

All previous spacecraft encounters with small solar-system bodies, such as asteroids and comets, have been flybys (e.g. Galileo's flybys of the asteroids Gaspra and Ida). Several future projects plan to build on the flyby experience and progress to the next level with rendezvous and orbit missions to small bodies. This presents several new issues and challenges for navigation which have never been considered before. This paper addresses these challenges by characterizing the different phases of a small body rendezvous and by describing the navigation requirements and goals of each phase. Prior to the encounter with the small body, improvements to its ephemeris and initial estimates of its physical parameters, e.g. size, shape, mass, rotation rate, rotation pole, and possibly outgassing, are made as accurately as ground-based measurements allow. This characterization can take place over years...

Helfrich, C. E.; Scheeres, D. J.; Williams, B. G.; Bollman, W. E.; Davis, R. P.; Synnott, S. P.; Yeomans, D. K.

1994-01-01

87

Towards the string dual of tumbling and cascading gauge theories  

E-print Network

We build type IIB backgrounds that can be interpreted as the dual description of field theories in which the dynamics shows many non-trivial phenomena, generalizing the baryonic branch of the Klebanov-Strassler system. We illustrate the steps of the explicit construction with a particularly interesting example. The dual field theory exhibits the expected behavior of an N=1 supersymmetric gauge theory which, over different ranges of the radial direction, is undergoing a cascade of Seiberg dualities, a period of running, a cascade of Higgsings (tumbling) and finally gaugino condensation.

Eduardo Conde; Jerome Gaillard; Carlos Nunez; Maurizio Piai; Alfonso V. Ramallo

2011-12-14

88

Grinding media oscillation: effect on torsional vibrations in tumble mills  

E-print Network

of Test Rig Figure 3.2 Exploded View of Test Rig 21 Figure 3.3 shows the schematic diagram of the tumble mill and its parts. The mill is made of a PVC pipe of 12? (0.3 m) inside diameter and 4? (0.1 m) length. The wall thickness of PVC... mm) diameter attached to this Plexiglas cover at its center to serve as a filling door. Through this filling door one can load or unload the mill with grinding media. The other side of the PVC mill is closed with a 12?? (0.32 m) diameter, 3/8? (10...

Toram, Kiran Kumar

2005-11-01

89

Automated Rendezvous and Capture System Development and Simulation for NASA  

NASA Technical Reports Server (NTRS)

The United States does not have an Automated Rendezvous and Capture Docking (AR&C) capability and is reliant on manned control for rendezvous and docking of orbiting spacecraft. T h i s reliance on the labor intensive manned interface for control of rendezvous and docking vehicles has a significant impact on the cost of the operation of the International Space Station (ISS) and precludes the use of any U.S. expendable launch capabilities for Space Station resupply. The Marshall Space Flight Center (MSFC) has conducted pioneering research in the development of an automated rendezvous and capture (or docking) (AR&C) system for U.S. space vehicles. This A M C system was tested extensively using hardware-in-the-loop simulations in the Flight Robotics Laboratory, and a rendezvous sensor, the Video Guidance Sensor was developed and successfully flown on the Space Shuttle on flights STS-87 and STS-95, proving the concept of a video- based sensor. Further developments in sensor technology and vehicle and target configuration have lead to continued improvements and changes in AR&C system development and simulation. A new Advanced Video Guidance Sensor (AVGS) with target will be utilized as the primary navigation sensor on the Demonstration of Autonomous Rendezvous Technologies (DART) flight experiment in 2004. Realtime closed-loop simulations will be performed to validate the improved AR&C systems prior to flight.

Roe, Fred D.; Howard, Richard T.; Murphy, Leslie

2004-01-01

90

Automated rendezvous and capture system development and simulation for NASA  

NASA Astrophysics Data System (ADS)

The United States does not have an Automated Rendezvous and Capture/Docking (AR&C) capability and is reliant on manned control for rendezvous and docking of orbiting spacecraft. This reliance on the labor intensive manned interface for control of rendezvous and docking vehicles has a significant impact on the cost of the operation of the International Space Station (ISS) and precludes the use of any U.S. expendable launch capabilities for Space Station resupply. The Marshall Space Flight Center (MSFC) has conducted pioneering research in the development of an automated rendezvous and capture (or docking) (AR&C) system for U.S. space vehicles. This AR&C system was tested extensively using hardware-in-the-loop simulations in the Flight Robotics Laboratory, and a rendezvous sensor, the Video Guidance Sensor was developed and successfully flown on the Space Shuttle on flights STS-87 and STS-95, proving the concept of a video- based sensor. Further developments in sensor technology and vehicle and target configuration have lead to continued improvements and changes in AR&C system development and simulation. A new Advanced Video Guidance Sensor (AVGS) with target will be utilized as the primary navigation sensor on the Demonstration of Autonomous Rendezvous Technologies (DART) flight experiment in 2004. Realtime closed-loop simulations will be performed to validate the improved AR&C systems prior to flight.

Roe, Fred D.; Howard, Richard T.; Murphy, Leslie

2004-09-01

91

RIGID BODY INERTIA ESTIMATION WITH APPLICATIONS TO THE CAPTURE OF A TUMBLING SATELLITE  

E-print Network

343 AAS 09-123 RIGID BODY INERTIA ESTIMATION WITH APPLICATIONS TO THE CAPTURE OF A TUMBLING SATELLITE Daniel Sheinfeld* and Stephen Rock A framework for rigid-body inertia estimation is presented forces to the tumbling satellite, and knowledge of the inertia properties of the satellite is necessary

92

OPTIMAL DESPIN OF A TUMBLING SATELLITE WITH AN ARBITRARY THRUSTER CONFIGURATION, INERTIA MATRIX,  

E-print Network

1 OPTIMAL DESPIN OF A TUMBLING SATELLITE WITH AN ARBITRARY THRUSTER CONFIGURATION, INERTIA MATRIX to despin a tumbling satellite with known, but arbitrary thruster configuration, inertia matrix, and cost of impulsive thrusters, arbitrary inertia matrix, and a minimum fuel consumption cost functional. The control

93

Rough and Tumble, Friendship, and Dominance in Schoolchildren: Evidence for Continuity and Change with Age.  

ERIC Educational Resources Information Center

Investigated play-fighting and chasing among 7-, 9-, and 11-year-olds in their school playground, where rough and tumble behaviors occupied approximately 10 percent of the time of 94 students. Findings indicated that rough and tumble tended to occur in a friendly, nonaggressive context. The importance of partner's strength increased with age.…

Humphreys, Anne P.; Smith, Peter K.

1987-01-01

94

Elementary-School Children's Rough-and-Tumble Play and Social Competence.  

ERIC Educational Resources Information Center

Observations of playground behavior of kindergarteners and second- and fourth-grade students suggested that rough-and-tumble play led to games-with-rules for popular children, and to aggression for rejected children. Findings are discussed in terms of possible effects of the sociometric composition of rough-and-tumble play groups. (RH)

Pellegrini, A. D.

1988-01-01

95

TALON and CRADLE: Systems for the rescue of tumbling spacecraft and astronauts  

NASA Technical Reports Server (NTRS)

Advanced pressure suit and tool designs are beginning to allow extravehicular astronauts to repair space vehicles and so increase mission life and system reliability. A common spacecraft failure that is a severe challenge to the rescue mission planner is loss of attitude control resulting in tumbling motion. If an extravehicular astronaut flying the Manned Maneuvering Unit (MMU) 'falls' into a tumble, the result could be loss of life. TALON (Tumble Arresting Large Oscillation Nullifier) is a device capable of capturing a target in an uncontrolled three-axis tumble. CRADLE (Concentric Rotating Astronaut Detumble Lifesaving Equipment) is a similar device sized to rescue a suited astronaut. The two rescue vehicles work on the same basic principle. They are structural shells with articulated limbs which can surround a tumbling target and thus align both the chaser and target centers of mass (CM).

Idle, Dunning, V

1991-01-01

96

Advanced Multipurpose Rendezvous Tracking System Study  

NASA Technical Reports Server (NTRS)

Rendezvous and docking (R&D) sensors needed to support Earth orbital operations of vehicles were investigated to determine the form they should take. An R&D sensor must enable an interceptor vehicle to determine both the relative position and the relative attitude of a target vehicle. Relative position determination is fairly straightforward and places few constraints on the sensor. Relative attitude determination, however, is more difficult. The attitude is calculated based on relative position measurements of several reflectors placed in a known arrangement on the target vehicle. The constraints imposed on the sensor by the attitude determination method are severe. Narrow beamwidth, wide field of view (fov), high range accuracy, and fast random scan capability are all required to determine attitude by this method. A consideration of these constraints as well as others imposed by expected operating conditions and the available technology led to the conclusion that the sensor should be a cw optical radar employing a semiconductor laser transmitter and an image dissector receiver.

Laurie, R. J.; Sterzer, F.

1982-01-01

97

Automated Rendezvous and Capture System Development and Simulation for NASA  

NASA Technical Reports Server (NTRS)

The United States does not have an Automated Rendezvous and Capture/Docking (AR and C) capability and is reliant on manned control for rendezvous and docking of orbiting spacecraft. This reliance on the labor intensive manned interface for control of rendezvous and docking vehicles has a significant impact on the cost of the operation of the International Space Station (ISS) and precludes the use of any U.S. expendable launch capabilities for Space Station resupply. The Soviets have the capability to autonomously dock in space, but their system produces a hard docking with excessive force and contact velocity. Automated Rendezvous and Capture/Docking has been identified as a key enabling technology for the Space Launch Initiative (SLI) Program, DARPA Orbital Express and other DOD Programs. The development and implementation of an AR&C capability can significantly enhance system flexibility, improve safety, and lower the cost of maintaining, supplying, and operating the International Space Station. The Marshall Space Flight Center (MSFC) has conducted pioneering research in the development of an automated rendezvous and capture (or docking) (AR and C) system for U.S. space vehicles. This AR&C system was tested extensively using hardware-in-the-loop simulations in the Flight Robotics Laboratory, and a rendezvous sensor, the Video Guidance Sensor was developed and successfully flown on the Space Shuttle on flights STS-87 and STS-95, proving the concept of a video- based sensor. Further developments in sensor technology and vehicle and target configuration have lead to continued improvements and changes in AR&C system development and simulation. A new Advanced Video Guidance Sensor (AVGS) with target will be utilized on the Demonstration of Autonomous Rendezvous Technologies (DART) flight experiment in 2004.

Roe, Fred D.; Howard, Richard T.; Murphy, Leslie

2004-01-01

98

Navigation capability for an ion drive rendezvous with Halley's Comet  

NASA Technical Reports Server (NTRS)

An analysis has been conducted in connection with plans for a study of Halley's Comet during its 1986 apparition. The use of low-thrust vehicles, utilizing an ion drive system, is being considered for a comet rendezvous mission. A preliminary trajectory for the Halley rendezvous mission calls for launch on June 20, 1982, followed by rendezvous on December 21, 1985. The navigation analysis described focuses on the terminal approach to Halley, the 60-day period preceding rendezvous. Navigation analysis assumptions are examined, taking into account navigation error sources, radio tracking, onboard optical data, earth-based comet observations, and orbit determination and guidance strategies. The preliminary mission design considers a rendezvous at approximately 56,000 km from the comet nucleus (6,000 km outside the dust envelope). Navigation performance is measured in terms of comet-relative position and velocity errors at encounter. Variations to the baseline navigation study provide illustrations concerning the close link between delivery accuracy and stochastic thrust errors.

Thornton, C. L.; Jacobson, R. A.

1977-01-01

99

Crossover from tumbling to tank-treading-like motion in dense simulated suspensions of red blood cells  

E-print Network

Via computer simulations, we provide evidence that the shear rate induced red blood cell tumbling-to-tank-treading transition also occurs at quite high volume fractions, where collective effects are important. The transition takes place as the ratio of suspension stress to the characteristic cell membrane stress exceeds a certain value, independent of volume fraction and cell deformability. This value coincides with that for a transition from an orientationally less ordered to a highly ordered phase. The average cell deformation does not show any signature of the transition, but rather follows a simple scaling law independent of volume fraction.

Timm Krüger; Markus Gross; Dierk Raabe; Fathollah Varnik

2013-07-02

100

A Monte-Carlo performance analysis of Kalman filter and targeting algorithms for autonomous orbital rendezvous  

E-print Network

Autonomous orbital rendezvous with an orbiting sample (OS) is seen as an enabling technology for a Mars Sample Return (MSR) mission, so several demonstrations have been planned. With CNES cooperation a proposed rendezvous ...

Vaughan, Andrew Thomas, 1979-

2004-01-01

101

Apollo-Lunar Orbital Rendezvous Technique  

NASA Technical Reports Server (NTRS)

Apollo-Lunar Orbital Rendezvous Technique. The film shows artists rendition of the spacecrafts, boosters, and flight of the Apollo lunar missions. The Apollo spacecraft will consist of three modules: the manned Command Module; the Service Module, which contains propulsion systems; and the Lunar Excursion Module (LEM) to carry astronauts to the moon and back to the Command and Service Modules. The spacecraft will be launched via a three-stage Saturn booster. The first stage will provide 7.5 million pounds of thrust from five F-1 engines for liftoff and initial powered flight. The second stage will develop 1 million pounds of thrust from five J-2 engines to boost the spacecraft almost into Earth orbit. Immediately after ignition of the second stage, the Launch Escape System will be jettisoned. A single J-2 engine in the S4B stage will provide 200,000 pounds of thrust to place the spacecraft in an earth parking orbit. It also will be used to propel the spacecraft into a translunar trajectory, then it will separate from the Apollo Modules. Onboard propulsion systems will be used to insert the spacecraft into lunar orbit. Two astronauts will enter the LEM, which will separate from the command and service modules. The LEM will go into elliptical orbit and prepare for landing. The LEM will lift off of the Moon's surface to return to the Command and Service Modules, and most likely be left in lunar orbit. After leaving the Moon's orbit, and shortly before entering Earth's orbit, the Service Module will be ejected. The Command Module will be oriented for reentry into the Earth's atmosphere. A drogue parachute will deploy at approximately 50,000 feet, followed by the main parachute system for touchdown. [Entire movie available on DVD from CASI as Doc ID 20070030988. Contact help@sti.nasa.gov

1963-01-01

102

Determination of tailless aircraft tumbling and stability characteristics through computational fluid dynamics  

NASA Astrophysics Data System (ADS)

Tailless aircraft configurations such as flying wings are susceptible to tumbling. Tumbling involves an autorotative pitching motion primarily about an axis parallel to the aircraft's lateral axis combined with planar translation. Tumbling is the suspected cause of a tailless aircraft (Northrop YB-49) crash in the late 1940s and is a potential problem for future flying wing and blended wing body aircraft. It may be difficult if not impossible for a tailless aircraft to escape the tumbling motion once it begins. It is therefore important for aircraft designers to know the causes of tumbling in order to prevent its onset. Tumbling has been demonstrated in qualitative free-flight wind tunnel experiments, but few have attempted to quantify the motion using computational fluid dynamics. The purpose of this research is to use computational fluid dynamics to study the tumbling characteristics of a tailless aircraft and then determine dynamic stability information from the simulations. Specifically, the effects of initial conditions, degrees-of-freedom, Reynolds number, and aircraft static margin will be investigated. Lumped pitch damping derivatives will be determined from the simulations.

Saephan, Syta

103

Production of mineral aggregates in quartz tumbling experiments  

NASA Astrophysics Data System (ADS)

Introduction Tumbling experiments with quartz sand with the purpose of tracing the effect of broken bonds in mineral surfaces resulted in an unexpected production of aggregates. These aggregates are a few microns in diameter, spherical and resembling tiny white "snowballs." Particle comminution by aeolian and other natural weathering processes are known in soil science and is often seen as an increase of fine particles towards the top of soil profiles (Nřrnberg, P. 1987, 1988, 2002, J.S. Wright 2007). When mineral grains collide in aeolian processes they break up along weakness zones in the crystal lattice. This mechanism causes broken bonds between atoms in the crystal lattice and results in reactive groups in the mineral surface. This mechanism provides the background for experiments to investigate the oxidation processes of magnetite on the planet Mars. The primary magnetic iron oxide phase on Mars is to day known to be magnetite and the colour of the dust on Mars is most likely due to hematite. To investigate if the oxidation process could take place without going over dissolution and precipitation in water, experiments with tumbling of quartz grains in sealed glass containers along with magnetite were started. The idea was that activated bonds at the surface of quartz could oxidize magnetite and convert it to hematite over time. This proved to be the case (Merrison, J.P. et al. 2010). However, in these experiments we observed the formation of the white aggregates which has been the subject of the study that we present here. Results of tumbling experiments Commercially available quarts (Merck) was sieved to obtain the fraction between 125 and 1000 µm. This fraction was tumbled in glass containers for months and resulted in production of a significant amount of fine grained material (Merrison, J.P et al. 2010). A part of this fine fraction consists of the "snowball"-like aggregates which is a fragile element with relatively high specific surface. The physical properties of these structures will be discussed in this paper. Nřrnberg, P. 1977: Soil Profile Development in Sands of Varying Age in Vendsyssel, Denmark. Catena, 4, 165-179. Nřrnberg, P. 1980: Mineralogy of a podzol formed in sandy materials in Northern Denmark. Geoderma, 24, 25-43. Nřrnberg, P. 2002: Particle comminution and aeolian addition in young dune sand soils. Transactions, 17th World Congress of Soil Science, Bangkok, Thailand, Symp. 25, pp. 9. Janet S. Wright, Janet S. 2007: An overview of the role of weathering in the production of quartz silt Sedimentary Geology, 202, 337-351 Merrison, J.P., Gunnlaugsson, H.P., Nřrnberg, P., Jensen, A.E., Rasmussen, K.R. 2007: Determination of the Wind Induced Detachment Threshold for Granular Material on Mars using Wind Tunnel Simulations. Icarus, 191, 568-580.

Nřrnberg, Per; Finster, Kai; Pall Gunnlaugsson, Haraldur; Knak Jensen, Svend; Merrison, Jonathan Peter

2013-04-01

104

Automated space vehicle control for rendezvous proximity operations  

NASA Technical Reports Server (NTRS)

Rendezvous during the unmanned space exploration missions, such as a Mars Rover/Sample Return will require a completely automatic system from liftoff to docking. A conceptual design of an automated rendezvous, proximity operations, and docking system is being implemented and validated at the Johnson Space Center (JSC). The emphasis is on the progress of the development and testing of a prototype system for control of the rendezvous vehicle during proximity operations that is currently being developed at JSC. Fuzzy sets are used to model the human capability of common sense reasoning in decision-making tasks and such models are integrated with the expert systems and engineering control system technology to create a system that performs comparably to a manned system.

Lea, Robert N.

1988-01-01

105

Automated space vehicle control for rendezvous proximity operations  

NASA Technical Reports Server (NTRS)

Rendezvous during the unmanned space exploration missions, such as a Mars Rover/Sample Return will require a completely automatic system from liftoff to docking. A conceptual design of an automated rendezvous, proximity operations, and docking system is being implemented and validated at the Johnson Space Center (JSC). The emphasis is on the progress of the development and testing of a prototype system for control of the rendezvous vehicle during proximity operations that is currently being developed at JSC. Fuzzy sets are used to model the human capability of common sense reasoning in decision making tasks and such models are integrated with the expert systems and engineering control system technology to create a system that performs comparably to a manned system.

Lea, Robert N.

1988-01-01

106

Robust H? Control for Spacecraft Rendezvous with a Noncooperative Target  

PubMed Central

The robust H? control for spacecraft rendezvous with a noncooperative target is addressed in this paper. The relative motion of chaser and noncooperative target is firstly modeled as the uncertain system, which contains uncertain orbit parameter and mass. Then the H? performance and finite time performance are proposed, and a robust H? controller is developed to drive the chaser to rendezvous with the non-cooperative target in the presence of control input saturation, measurement error, and thrust error. The linear matrix inequality technology is used to derive the sufficient condition of the proposed controller. An illustrative example is finally provided to demonstrate the effectiveness of the controller. PMID:24027446

Wu, Shu-Nan; Zhou, Wen-Ya; Tan, Shu-Jun; Wu, Guo-Qiang

2013-01-01

107

A comparative analysis of the layout back somersault and full twisting back somersault in tumbling  

E-print Network

A COMPARATIVE ANALYSIS OF THE LAYOUT BACK SOMERSAULT AND FULL TWISTING BACK SOMERSAULT IN TUMBLING A Thesis by HARRY SAMUEL SEIDEL, JR. Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE August 1976 Major Subject: Health and Physical Education A COMPARATIVE ANALYSIS OF THE LAYOUT BACK SOMERSAULT AND FULL TWISTING BACK SOMERSAULT IN TUMBLING A Thesis by HARRY SAMUEL SEIDEL, JR. Approved as to style...

Seidel, Harry Samuel

2012-06-07

108

ENHANCING SOCIAL COORDINATION 1 Rendezvousing with Location-Aware Devices  

E-print Network

this information will impact social behaviours. Location awareness is fundamentally different than active verbal to significantly impact users' social coordination, particularly while rendezvousing. It is important that we explore how new technologies influence social behaviours and communication in order to realize their full

Toronto, University of

109

Spectrum Sharing with Rotating Radar: Implications for Cognitive Radio Rendezvous  

E-print Network

measurements of an actual radar system, this paper studies how an ad hoc network of cognitive radios lackingSpectrum Sharing with Rotating Radar: Implications for Cognitive Radio Rendezvous Jeffrey D. Poston--To date, research on spectrum sharing has almost exclusively studied dynamic access limited to agility

Buehrer, R. Michael

110

Optimal analytic rendezvous using Clohessy-Wiltshire equations  

NASA Technical Reports Server (NTRS)

The optimal solution time that minimizes the sum of the two applied impulses necessary to rendezvous is obtained analytically for the Clohessy-Wiltshire equations with a linear gravity model assumption. A plume impingement inequality constraint on the solution is examined, and an optimal policy is developed. Numerical tests are conducted to verify the analysis and to illustrate the optimal solution algorithm.

Jezewski, D. J.; Donaldson, J. D.

1978-01-01

111

Autonomous Mars ascent and orbit rendezvous for earth return missions  

NASA Technical Reports Server (NTRS)

The details of tha assessment of autonomous Mars ascent and orbit rendezvous for earth return missions are presented. Analyses addressing navigation system assessments, trajectory planning, targeting approaches, flight control guidance strategies, and performance sensitivities are included. Tradeoffs in the analysis and design process are discussed.

Edwards, H. C.; Balmanno, W. F.; Cruz, Manuel I.; Ilgen, Marc R.

1991-01-01

112

Affect of Shape Abnormality in Foot and Toenail on Tumbling of Aged  

NASA Astrophysics Data System (ADS)

There is the increasing concern of the society to prevent the tumbling of the aged. The study of the static, as well as dynamic aspects, such as the muscular strength of the lower-limb and the postural stability, should be developed, especially from the viewpoint of the aged. This paper focuses on the external observation of the foot and toenail, as being correlated to the physical functions of the lower-limb against tumbling. The lower-limb functions are evaluated in terms of the 10 m walking time, the toe-gap force and single-foot standing period. The correlation to the personal tumbling experiences is also examined. It is seen that the groups, which exhibit external abnormalities in the foot and the toenail, generally decline in the muscular strength and postural stability. They also have more frequent tumbling experiences and express in their concern of the danger of tumbling. It seems that those shapes abnormalities can indicate, to some extent, the tumbling danger of the aged.

Yamashita, Kazuhiko; Nomoto, Yohei; Umezawa, Jun; Miyagawa, Haruki; Kawasumi, Masashi; Koyama, Hironori; Saito, Masao

113

Development of automated rendezvous and proximity operations techniques for rendezvous and close-in operations and satellite servicing  

NASA Technical Reports Server (NTRS)

The development of freeflyer maneuvering system and shuttle orbiter flight profiles and hardware/software requirements that will provide and automated rendezvous, station keeping, and docking capability is discussed. Automated control techniques, sensors, target vehicle requirements, and a soft docking system are addressed.

Becker, R. W.; Anderson, R. L.

1982-01-01

114

Autonomous satellite rendezvous and docking using lidar and model based vision  

NASA Astrophysics Data System (ADS)

Servicing satellites on-orbit requires ability to rendezvous and dock by an unmanned spacecraft with no or minimum human input. Novel imaging sensors and computer vision technologies are required to detect a target spacecraft at a distance of several kilometers and to guide the approaching spacecraft to contact. Current optical systems operate at much shorter distances, provide only bearing and range towards the target, or rely on visual targets. Emergence of novel LIDAR technologies and computer vision algorithms will lead to a new generation of rendezvous and docking systems in the near future. Such systems will be capable of autonomously detecting a target satellite at a distance of a few kilometers, estimating its bearing, range and relative orientation under virtually any illumination, and in any satellite pose. At MDA Space Missions we have developed a proof-of-concept vision system that uses a scanning LIDAR to estimate pose of a known satellite. First, the vision system detects a target satellite, and estimates its bearing and range. Next, the system estimates the full pose of the satellite using a 3D model. Finally, the system tracks satellite pose with high accuracy and update rate. Estimated pose provides information where the docking port is located even if the port is not visible and enables selecting more efficient flight trajectory. The proof-of-concept vision system has been integrated with a commercial time-of-flight LIDAR and tested using a moving scaled satellite replica in the MDA Vision Testbed.

Jasiobedzki, Piotr; Se, Stephen; Pan, Tong; Umasuthan, Manickam; Greenspan, Michael

2005-05-01

115

Dynamical properties of nematic liquid crystals subjected to shear flow and magnetic fields: Tumbling instability and nonequilibrium fluctuations  

NASA Astrophysics Data System (ADS)

We investigate the dynamical properties of monodomain nematic liquid crystals under shear flow and magnetic fields on the basis of the Ericksen-Leslie theory. Stable and unstable states appear depending on the magnetic field and the shear rate. The trajectory of the unstable state shows tumbling motion. The phase diagram of these states is plotted as a function of the three components of the magnetic field at a constant shear rate. The phase diagram changes depending on the viscous properties of different types of nematic liquid crystals. In this nonequilibrium steady state, we calculate the correlation function of director fluctuations and the response function, and discuss the nonequilibrium fluctuations and the modified fluctuation-dissipation relation in connection with nonconservative forces due to shear flow.

Fatriansyah, Jaka Fajar; Orihara, Hiroshi

2013-07-01

116

Genetic algorithm based fuzzy control of spacecraft autonomous rendezvous  

NASA Technical Reports Server (NTRS)

The U.S. Bureau of Mines is currently investigating ways to combine the control capabilities of fuzzy logic with the learning capabilities of genetic algorithms. Fuzzy logic allows for the uncertainty inherent in most control problems to be incorporated into conventional expert systems. Although fuzzy logic based expert systems have been used successfully for controlling a number of physical systems, the selection of acceptable fuzzy membership functions has generally been a subjective decision. High performance fuzzy membership functions for a fuzzy logic controller that manipulates a mathematical model simulating the autonomous rendezvous of spacecraft are learned using a genetic algorithm, a search technique based on the mechanics of natural genetics. The membership functions learned by the genetic algorithm provide for a more efficient fuzzy logic controller than membership functions selected by the authors for the rendezvous problem. Thus, genetic algorithms are potentially an effective and structured approach for learning fuzzy membership functions.

Karr, C. L.; Freeman, L. M.; Meredith, D. L.

1990-01-01

117

Minispacecraft for a multiple-asteroid rendezvous mission  

NASA Technical Reports Server (NTRS)

The development of the Multiple Asteroid Rendezvous Tracker and Explorer spacecraft, which is designed for the analysis of the composition and the motion of several main-belt asteroids, is discussed. The mission includes a laboratory lander craft (the main lab) and several minispacecraft. The main lab will be equipped with a complete sample analysis laboratory and multiple external sensors. Each of the minispacecraft, which are much smaller than the main lab and contain only a few instruments, is targeted to rendezvous with an asteroid, on which it will land and perform a preliminary surface analysis. This will identify the most scientifically interesting asteroid. The main lab will then be sent to this asteroid for performing a detailed analysis including soil sampling.

Fowler, Wallace T.; Pinon, Elfego, III; Roesset, Peter J.; Striepe, Scott A.; Korsmeyer, David J.

1993-01-01

118

Cognitive Vision for Autonomous Satellite Rendezvous and Docking  

Microsoft Academic Search

We present a cognitively-controlled vision system that com- bines low-level object recognition and tracking with high-level symbolic reasoning for the purpose of solving difficult space robotics problems—satellite rendezvous and docking. The rea- soning module, which encodes a model of the environment, performs deliberation to 1) guide the vision system in a task- directed manner, 2) activate vision modules depending on

Faisal Qureshi; Demetri Terzopoulos; Piotr Jasiobedzki

2005-01-01

119

Low-energy multiple rendezvous of main belt asteroids  

NASA Technical Reports Server (NTRS)

An approach to multiple asteroid rendezvous missions to the main belt region is proposed. In this approach key information which consists of a launch date and delta V can be generated for all possible pairs of asteroids satisfying specific constraints. This information is made available on a computer file for 1000 numbered asteroids with reasonable assumptions, limitations, and approximations to limit the computer requirements and the size of the data file.

Penzo, Paul A.; Bender, David F.

1992-01-01

120

Fast solar sail rendezvous mission to near Earth asteroids  

NASA Astrophysics Data System (ADS)

The concept of fast solar sail rendezvous missions to near Earth asteroids is presented by considering the hyperbolic launch excess velocity as a design parameter. After introducing an initial constraint on the hyperbolic excess velocity, a time optimal control framework is derived and solved by using an indirect method. The coplanar circular orbit rendezvous scenario is investigated first to evaluate the variational trend of the transfer time with respect to different hyperbolic excess velocities and solar sail characteristic accelerations. The influence of the asteroid orbital inclination and eccentricity on the transfer time is studied in a parametric way. The optimal direction and magnitude of the hyperbolic excess velocity are identified via numerical simulations. The found results for coplanar circular scenarios are compared in terms of fuel consumption to the corresponding bi-impulsive transfer of the same flight time, but without using a solar sail. The fuel consumption tradeoff between the required hyperbolic excess velocity and the achievable flight time is discussed. The required total launch mass for a particular solar sail is derived in analytical form. A practical mission application is proposed to rendezvous with the asteroid 99942 Apophis by using a solar sail in combination with the provided hyperbolic excess velocity.

Zeng, Xiangyuan; Gong, Shengping; Li, Junfeng

2014-12-01

121

Autonomous rendezvous, docking, and landing system using cruise missile technologies  

NASA Astrophysics Data System (ADS)

General Dynamics has been developing an Autonomous Rendezvous Docking and Landing (ARD&L) system that utilizes cruise missile technologies. In November 1990 the Autonomous Rendezvous and Docking (AR&D) system was first demonstrated for members of NASA's Strategic Avionics Technology Working Group (SATWG). This simulation utilized prototype hardware from the Cruise Missile and Advanced Centaur Avionics systems. The objective was to show that all the accuracy, reliability, and operational requirements established for a spacecraft to dock with Space Station Freedom could be met by the proposed system. Rapid prototyping techniques were used to evaluate the proposed system in a real time, hardware in the loop simulation of the rendezvous and docking reference mission. The simulation is currently being upgraded to test an Autonomous Approach and Landing (AA&L) system. Both systems use inertial guidance and control systems supplemented by the Global Positioning System (GPS) and an Image Processing System (IPS), for target recognition and tracking. The IPS includes a general purpose multiprocessor computer and a selected suite of sensors that will provide the required relative position and orientation data. Graphic displays can provide the astronaut/operator with realtime guidance and navigation data with enhanced video or sensor imagery.

Jones, Ruel E.

1992-07-01

122

Supervised autonomous rendezvous and docking system technology evaluation  

NASA Technical Reports Server (NTRS)

Technology for manned space flight is mature and has an extensive history of the use of man-in-the-loop rendezvous and docking, but there is no history of automated rendezvous and docking. Sensors exist that can operate in the space environment. The Shuttle radar can be used for ranges down to 30 meters, Japan and France are developing laser rangers, and considerable work is going on in the U.S. However, there is a need to validate a flight qualified sensor for the range of 30 meters to contact. The number of targets and illumination patterns should be minimized to reduce operation constraints with one or more sensors integrated into a robust system for autonomous operation. To achieve system redundancy, it is worthwhile to follow a parallel development of qualifying and extending the range of the 0-12 meter MSFC sensor and to simultaneously qualify the 0-30(+) meter JPL laser ranging system as an additional sensor with overlapping capabilities. Such an approach offers a redundant sensor suite for autonomous rendezvous and docking. The development should include the optimization of integrated sensory systems, packaging, mission envelopes, and computer image processing to mimic brain perception and real-time response. The benefits of the Global Positioning System in providing real-time positioning data of high accuracy must be incorporated into the design. The use of GPS-derived attitude data should be investigated further and validated.

Marzwell, Neville I.

1991-01-01

123

Finding rendezvous: An approach to locating Rocky Mountain Rendezvous sites through use of historic documents, geophysical survey, and LiDAR  

NASA Astrophysics Data System (ADS)

The general locations of the Rocky Mountain Rendezvous have been known to historians through documentary evidence since the mid to late 1800s. While the approximate locations of the rendezvous sites provided through historic documents have sufficed for the placement of signs and markers commemorating these annual events, archaeologists seeking to learn more about the yearly gathering of mountain men and native peoples through excavations need a more precise area to begin their search on the landscape. The exact locations of the Rocky Mountain Rendezvous are yet unknown in the sense of an archaeologist visiting a rendezvous site, trowel in hand, and hoping to unearth a small portion of fur trade history. In this study, I present a method for moving from the approximate locations for the Rocky Mountain Rendezvous sites provided by historic documents to identifying specific rendezvous archaeological sites through use of historic documents, geophysical survey, and GIS modeling. The first paper in this dissertation examines the demographics of the rendezvous. By use of historic documents, I present a method for estimating the number of people who may have been present at the rendezvous and winter camps from 1825 through 1829. By using this method for estimating people at the rendezvous, it becomes clear more native people were in attendance at the rendezvous and winter camps than trappers and traders of European descent. Once armed with the knowledge a rendezvous site should more closely resemble the archaeological signature of a Protohistoric native camp than a historic Euroamerican archaeological site, the search for a Protohistoric native camp to be mapped with geophysical survey instruments can begin. During this study, such a search resulted in the successful mapping of a portion of the camp surrounding a fur trading post on the banks of Powder River in east-central Wyoming. The final section in the dissertation will address the issue of where and how to focus a geophysical survey in hopes of finding the Protohistoric camp signature within the potential rendezvous locations identified in the historic documents. The study focuses on identifying potential survey areas along the Green River in western Wyoming considered highly probable to contain intact buried archaeological deposits dating to at least the early 1800s. A systematic survey is proposed focusing on areas not only identified through historic documentary research as being locations for the rendezvous, but also containing sediments holding intact deposits dating to the time of the fur trade.

Becker, Rory J.

124

A new approach to impulsive rendezvous near circular orbit  

NASA Astrophysics Data System (ADS)

A new approach is presented for the problem of planar optimal impulsive rendezvous of a spacecraft in an inertial frame near a circular orbit in a Newtonian gravitational field. The total characteristic velocity to be minimized is replaced by a related characteristic-value function and this related optimization problem can be solved in closed form. The solution of this problem is shown to approach the solution of the original problem in the limit as the boundary conditions approach those of a circular orbit. Using a form of primer-vector theory the problem is formulated in a way that leads to relatively easy calculation of the optimal velocity increments. A certain vector that can easily be calculated from the boundary conditions determines the number of impulses required for solution of the optimization problem and also is useful in the computation of these velocity increments. Necessary and sufficient conditions for boundary conditions to require exactly three nonsingular non-degenerate impulses for solution of the related optimal rendezvous problem, and a means of calculating these velocity increments are presented. A simple example of a three-impulse rendezvous problem is solved and the resulting trajectory is depicted. Optimal non-degenerate nonsingular two-impulse rendezvous for the related problem is found to consist of four categories of solutions depending on the four ways the primer vector locus intersects the unit circle. Necessary and sufficient conditions for each category of solutions are presented. The region of the boundary values that admit each category of solutions of the related problem are found, and in each case a closed-form solution of the optimal velocity increments is presented. Similar results are presented for the simpler optimal rendezvous that require only one-impulse. For brevity degenerate and singular solutions are not discussed in detail, but should be presented in a following study. Although this approach is thought to provide simpler computations than existing methods, its main contribution may be in establishing a new approach to the more general problem.

Carter, Thomas; Humi, Mayer

2012-04-01

125

Experimentally validated computations of flow, mixing and segregation of non-cohesive grains in 3D tumbling blenders  

Microsoft Academic Search

Granular mixing is a vital operation in food, chemical, and pharmaceutical industries. Although the tumbling blender is by far the most common device used to mix grains, surprisingly little is known about mixing or segregation in these devices. In this paper, we report the first fully three-dimensional (3D) particle dynamics simulations of granular dynamics in two standard industrial tumbling blender

Maher Moakher; Troy Shinbrot; Fernando J. Muzzio

2000-01-01

126

Statistics of tumbling of a single polymer molecule in shear flow  

E-print Network

We present experimental results on statistics of polymer orientation angles relatively to shear plane and tumbling times in shear flow with thermal noise. Strong deviation of probability distribution functions (PDF) of these parameters from Gaussian was observed and a good accord with theory was found. The scaling relations of PDF widths for both angles as a function of the control parameter $Wi$ are verified and compared with numerics. An universal exponential PDF tail for the tumbling times and its predicted scaling with $Wi$ are also tested experimentally against numerics.

Sergiy Gerashchenko; Victor Steinberg

2005-03-11

127

Theory of Tumbling Bodies Entering Planetary Atmospheres with Application to Probe Vehicles and the Australian Tektites  

NASA Technical Reports Server (NTRS)

The tumbling motion of aerodynamically stable bodies entering planetary atmospheres is analyzed considering that the tumbling, its arrest, and the subsequent oscillatory motion are governed by the equation for the fifth Painleve' transcendent. Results based on the asymptotic behavior of the transcendent are applied to study (1) the oscillatory behavior of planetary probe vehicles in relation to aerodynamic heating and loads and (2) the dynamic behavior of the Australian tektites on entering the Earth's atmosphere, under the hypothesis that their origin was the Moon.

Tobak, Murray; Peterson, Victor L.

1964-01-01

128

Emergent Run-and-Tumble Behavior in a Simple Model of Chlamydomonas with Intrinsic Noise  

E-print Network

Recent experiments on the green alga Chlamydomonas that swims using synchronized beating of a pair of flagella have revealed that it exhibits a run-and-tumble behavior similar to that of bacteria such as E. Coli. Using a simple purely hydrodynamic model that incorporates a stroke cycle and an intrinsic Gaussian white noise, we show that a stochastic run-and-tumble behavior could emerge, due to the nonlinearity of the combined synchronization-rotation-translation dynamics. This suggests the intriguing possibility that the alga might exploit nonlinear mechanics---as opposed to sophisticated biochemical circuitry as used by bacteria---to control its behavior.

Rachel R. Bennett; Ramin Golestanian

2012-11-14

129

Quality characteristics of a dry-cured lamb leg as affected by tumbling after dry-salting and processing time.  

PubMed

The aim of this study was to evaluate selected quality characteristics of a dry-cured lamb leg with different tumbling treatments after salting. The characteristics were measured at different processing times. Three batches of dry-cured lamb legs (nine legs per batch) were prepared with no-, short- and long-tumbling treatments, and microbial counts, NaCl, aw, proximate composition, pH, free fatty acids, water soluble nitrogen, volatile compounds, texture and colour were evaluated at days 1, 22 and 71 of processing. Furthermore, a descriptive sensory analysis (flavour and texture) was performed in the final product (day 71). Time-related changes were observed for most of the characteristics studied. The effect of tumbling was only observed for the sensory attribute pastiness that was higher in tumbled legs. Methyl-branched butanal was only detected in tumbled legs. PMID:24553493

Villalobos-Delgado, Luz H; Caro, Irma; Blanco, Carolina; Morán, Lara; Prieto, Nuria; Bodas, Raul; Giráldez, Francisco J; Mateo, Javier

2014-05-01

130

Analysis of the relative attitude estimation and control problem for satellite inspection and orbital rendezvous  

NASA Astrophysics Data System (ADS)

A key component of satellite inspection and orbital rendezvous missions is relative attitude estimation and control. This paper analyzes a specific angles-only relative attitude estimation concept where it is assumed that a chaser spacecraft is capable of processing onboard imagery of a resident space object (RSO) and identifying the pixel locations of preselected RSO features. The pixel measurements along with chaser gyro and star camera data are processed by an extended Kalman filter to provide continuous estimates of the relative position and attitude. A novel linear covariance program is used to evaluate the effects of feature-tracking camera errors, gyro errors, star camera errors, measurement rates, and translation and rotational disturbances on relative navigation performance. Linear covariance techniques are further employed to evaluate the closed-loop performance of a relative attitude and position control system.

Geller, D.

2007-06-01

131

Effects of Location-Aware Computing On Rendezvous David Dearman, Kirstie Hawkey, and Kori M. Inkpen  

E-print Network

Effects of Location-Aware Computing On Rendezvous Behaviour David Dearman, Kirstie Hawkey, and Kori is to investigate how location-aware technology impacts rendezvousing behaviour (meeting at an agreed upon time M. Inkpen Dalhousie University, Faculty of Computer Science, 6050 University Ave., Halifax, NS

Hawkey, Kirstie

132

Social Gravity: A Virtual Elastic Tether for Casual, Privacy-Preserving Pedestrian Rendezvous  

E-print Network

Social Gravity: A Virtual Elastic Tether for Casual, Privacy-Preserving Pedestrian Rendezvous John, simple and privacy-preserving mee- tups. Our design provides cues which allow dynamic co- ordination of rendezvous without revealing user's positions. Using accelerometers and magnetometers, combined with GPS

Williamson, John

133

Social Gravity: A Virtual Elastic Tether for Casual, Privacy-Preserving Pedestrian Rendezvous  

E-print Network

Social Gravity: A Virtual Elastic Tether for Casual, Privacy-Preserving Pedestrian Rendezvous John, simple and privacy-preserving mee- tups. Our design provides cues which allow dynamic coor- dination of rendezvous without revealing users' positions. Using accelerometers and magnetometers, combined with GPS

Williamson, John

134

Multiple Agents RendezVous In a Ring in Spite of a Black Hole  

E-print Network

this problem when in the network there is a black hole: a stationary process located at a node that destroysMultiple Agents RendezVous In a Ring in Spite of a Black Hole Stefan Dobrev Paola Flocchini Giuseppe Prencipe Nicola Santoro§ Abstract The Rendezvous of anonymous mobile agents in a anonymous network

Santoro, Nicola

135

Integrated GPS\\/INS navigation system design for autonomous spacecraft rendezvous  

Microsoft Academic Search

The goal of the NASA Space Launch Initiative (SLI) program is to advance the technologies for the next generation reusable launch vehicle (RLV). The SLI program has identified automated rendezvous and docking as an area requiring further research and development. Currently, the Space Shuttle uses a partially manual system for rendezvous, but a fully automated system could be safer and

David Edward Gaylor

2003-01-01

136

Influences of agricultural practices on water quality of Tumbling Creek cave stream in Taney County, Missouri  

Microsoft Academic Search

Influences of agricultural practices on water quality of the Tumbling Creek cave stream are of particular interest because of the karst nature of the area and the recent implementation of a Better Management Practice (BMP). Water quality parameters, measured bi-weekly during one year, consisted of pH, turbidity, water temperature, specific conductivity, total dissolved solids, alkalinity, and chloride. Heavy metals, nutrient

H. Neill; M. Gutiérrez; T. Aley

2004-01-01

137

Practitioner Expertise: Creating Quality within the Daily Tumble of Events in Youth Settings  

ERIC Educational Resources Information Center

Practitioners in youth settings experience life on the ground as a tumble of events, shaped by a confluence of youth needs, institutional expectations, and other inputs. The quality of the setting is determined in part by practitioners' expertise in shaping and responding to these events. The situations that arise in practice, and how staff…

Larson, Reed W.; Rickman, Aimee N.; Gibbons, Colleen M.; Walker, Kathrin C.

2009-01-01

138

GYMNASTICS LESSONS Whether you want to learn how to tumble, get some exercise, or  

E-print Network

GYMNASTICS LESSONS Whether you want to learn how to tumble, get some exercise, or just have fun, you will find something that meets your gymnastic needs here. No previous experience necessary. We will be responsible for coming to the gymnastics room to pick up your children immediately after class. · If you

Beex, A. A. "Louis"

139

Factors during tumble drying that influence dimensional stability and distortion of cotton knitted fabrics  

Microsoft Academic Search

The length and width shrinkages, skewness, spirality and moisture content of three weft knitted cotton structures, plain single jersey, interlock and lacoste, were determined at regular intervals during tumble drying. Significant length and width shrinkages occurred in all three structures with the amount of shrinkage increasing rapidly in plain single jersey and lacoste as their moisture contents fell below 30

L. Higgins; S. C. Anand; M. E. Hall; D. A. Holmes

2003-01-01

140

Further Application of the Semenov Model to Evaluate the Possibility of Spontaneous Combustion in Tumble Dryers  

Microsoft Academic Search

Previously, Jones applied the Semenov boundary conditions and thermal explosion theory to the problem of predicting spontaneous combustion of laundered clothing in a commercial tumble dryer. This problem is revisited here with a modification of the limiting assumptions made in the previous work. Relaxation of the limiting assumptions (i.e., considering air flow through the drum) demonstrates that the self-heating processes

D. R. Morrison; R. A. Ogle

2008-01-01

141

Rough and Tumble Play Quality: Theoretical Foundations for a New Measure of Father-Child Interaction  

ERIC Educational Resources Information Center

Energetic, competitive, body-contact play (rough and tumble play (RTP)) is commonly observed among young children and is reported as an important feature of father-child relationships. Animal studies have demonstrated positive developmental effects of peer-peer play-wrestling, influencing cognitive and social outcomes. The purpose of this paper is…

Fletcher, Richard; StGeorge, Jennifer; Freeman, Emily

2013-01-01

142

Is Father-Child Rough-and-Tumble Play Associated with Attachment or Activation Relationships?  

ERIC Educational Resources Information Center

The activation relationship theory, primarily focused on parental stimulation of risk-taking along with parental control during exploration, predicts that boys will be activated more than girls by their fathers. This theory may explain why fathers engage in rough-and-tumble play (RTP) with children more frequently than mothers, especially with…

Paquette, Daniel; Dumont, Caroline

2013-01-01

143

Virtual reality applications to automated rendezvous and capture  

NASA Technical Reports Server (NTRS)

Virtual Reality (VR) is a rapidly developing Human/Computer Interface (HCI) technology. The evolution of high-speed graphics processors and development of specialized anthropomorphic user interface devices, that more fully involve the human senses, have enabled VR technology. Recently, the maturity of this technology has reached a level where it can be used as a tool in a variety of applications. This paper provides an overview of: VR technology, VR activities at Marshall Space Flight Center (MSFC), applications of VR to Automated Rendezvous and Capture (AR&C), and identifies areas of VR technology that requires further development.

Hale, Joseph; Oneil, Daniel

1991-01-01

144

Reference equations of motion for automatic rendezvous and capture  

NASA Technical Reports Server (NTRS)

The analysis presented in this paper defines the reference coordinate frames, equations of motion, and control parameters necessary to model the relative motion and attitude of spacecraft in close proximity with another space system during the Automatic Rendezvous and Capture phase of an on-orbit operation. The relative docking port target position vector and the attitude control matrix are defined based upon an arbitrary spacecraft design. These translation and rotation control parameters could be used to drive the error signal input to the vehicle flight control system. Measurements for these control parameters would become the bases for an autopilot or feedback control system (FCS) design for a specific spacecraft.

Henderson, David M.

1992-01-01

145

Rendezvous and proximity operations sensor candidates  

NASA Astrophysics Data System (ADS)

As part of an ESA study, RVD and proximity operations on autonomous smart sensors for guidance between spacecraft are discussed. Measurement parameters for the sensors include range, range resolution, and range rate between 20 km and 0.1 m, and angular and lateral relative position between 20 km and 0.1 m. Sensors examined include a PRN Ku-band microwave range and attitude sensor, a CW laser diode range and attitude sensor, and a solid state smart camera for near field guidance. The study suggests that autonomous spacecraft docking is realistic to the extent that pin-to-pin connections/alignment can be warranted, and provided that the expected lateral offset of the docking/matching items to the sensor view area is sufficiently precise.

Kunkel, B.; Hartl, Ph.; Fehse, W.

1985-02-01

146

Determination of Eros Physical Parameters for Near Earth Asteroid Rendezvous Orbit Phase Navigation  

NASA Technical Reports Server (NTRS)

Navigation of the orbit phase of the Near Earth steroid Rendezvous (NEAR) mission will re,quire determination of certain physical parameters describing the size, shape, gravity field, attitude and inertial properties of Eros. Prior to launch, little was known about Eros except for its orbit which could be determined with high precision from ground based telescope observations. Radar bounce and light curve data provided a rough estimate of Eros shape and a fairly good estimate of the pole, prime meridian and spin rate. However, the determination of the NEAR spacecraft orbit requires a high precision model of Eros's physical parameters and the ground based data provides only marginal a priori information. Eros is the principal source of perturbations of the spacecraft's trajectory and the principal source of data for determining the orbit. The initial orbit determination strategy is therefore concerned with developing a precise model of Eros. The original plan for Eros orbital operations was to execute a series of rendezvous burns beginning on December 20,1998 and insert into a close Eros orbit in January 1999. As a result of an unplanned termination of the rendezvous burn on December 20, 1998, the NEAR spacecraft continued on its high velocity approach trajectory and passed within 3900 km of Eros on December 23, 1998. The planned rendezvous burn was delayed until January 3, 1999 which resulted in the spacecraft being placed on a trajectory that slowly returns to Eros with a subsequent delay of close Eros orbital operations until February 2001. The flyby of Eros provided a brief glimpse and allowed for a crude estimate of the pole, prime meridian and mass of Eros. More importantly for navigation, orbit determination software was executed in the landmark tracking mode to determine the spacecraft orbit and a preliminary shape and landmark data base has been obtained. The flyby also provided an opportunity to test orbit determination operational procedures that will be used in February of 2001. The initial attitude and spin rate of Eros, as well as estimates of reference landmark locations, are obtained from images of the asteroid. These initial estimates are used as a priori values for a more precise refinement of these parameters by the orbit determination software which combines optical measurements with Doppler tracking data to obtain solutions for the required parameters. As the spacecraft is maneuvered; closer to the asteroid, estimates of spacecraft state, asteroid attitude, solar pressure, landmark locations and Eros physical parameters including mass, moments of inertia and gravity harmonics are determined with increasing precision. The determination of the elements of the inertia tensor of the asteroid is critical to spacecraft orbit determination and prediction of the asteroid attitude. The moments of inertia about the principal axes are also of scientific interest since they provide some insight into the internal mass distribution. Determination of the principal axes moments of inertia will depend on observing free precession in the asteroid's attitude dynamics. Gravity harmonics are in themselves of interest to science. When compared with the asteroid shape, some insight may be obtained into Eros' internal structure. The location of the center of mass derived from the first degree harmonic coefficients give a direct indication of overall mass distribution. The second degree harmonic coefficients relate to the radial distribution of mass. Higher degree harmonics may be compared with surface features to gain additional insight into mass distribution. In this paper, estimates of Eros physical parameters obtained from the December 23,1998 flyby will be presented. This new knowledge will be applied to simplification of Eros orbital operations in February of 2001. The resulting revision to the orbit determination strategy will also be discussed.

Miller, J. K.; Antreasian, P. J.; Georgini, J.; Owen, W. M.; Williams, B. G.; Yeomans, D. K.

1995-01-01

147

Optimization of multi-mode rendezvous trajectories with constraints  

NASA Astrophysics Data System (ADS)

Approximate numerical methods of optimization of spacecraft rendezvous trajectories are presented that make use of interior point algorithms for problems of linear programming of high dimensionality (tens to hundreds of thousands of variables). The basis of the methods is discretization of a trajectory into small segments in which maneuvers are allowed to be executed; for all segments sets of pseudo-impulses are introduced that determine the possible directions of the spacecraft thrust vector. The terminal conditions are presented in the form of a linear matrix equation. A matrix inequality for the sums of characteristic velocities of pseudo-impulses on each segment is used to make a transformation to the linear programming form. Spacecraft rendezvous trajectories are considered in the neighborhood of circular orbits with the use of multi-mode propulsion systems (including those with low thrust) and existence of boundary conditions at interior points and constraints on the time of operation of the propulsion system at separate segments of the trajectory.

Ulybyshev, Yu. P.

2008-04-01

148

An autonomous rendezvous and docking system using cruise missile technologies  

NASA Astrophysics Data System (ADS)

In November 1990 the Autonomous Rendezvous & Docking (AR&D) system was first demonstrated for members of NASA's Strategic Avionics Technology Working Group. This simulation utilized prototype hardware from the Cruise Missile and Advanced Centaur Avionics systems. The object was to show that all the accuracy, reliability and operational requirements established for a space craft to dock with Space Station Freedom could be met by the proposed system. The rapid prototyping capabilities of the Advanced Avionics Systems Development Laboratory were used to evaluate the proposed system in a real time, hardware in the loop simulation of the rendezvous and docking reference mission. The simulation permits manual, supervised automatic and fully autonomous operations to be evaluated. It is also being upgraded to be able to test an Autonomous Approach and Landing (AA&L) system. The AA&L and AR&D systems are very similar. Both use inertial guidance and control systems supplemented by GPS. Both use an Image Processing System (IPS), for target recognition and tracking. The IPS includes a general purpose multiprocessor computer and a selected suite of sensors that will provide the required relative position and orientation data. Graphic displays can also be generated by the computer, providing the astronaut / operator with real-time guidance and navigation data with enhanced video or sensor imagery.

Jones, Ruel Edwin

149

Autonomous control procedures for shuttle rendezvous proximity operations  

NASA Technical Reports Server (NTRS)

The results are presented of a study which uses fuzzy sets to model a Space Shuttle pilot's reasoning and actions while performing rendezvous proximity operation maneuvers. In this model fuzzy sets are used to simulate smooth and continuous actions as would be expected from an experienced pilot and to simulate common sense reasoning in the decision process. The present model assumes visual information available to the Shuttle pilot from the Shuttle Crew Optical Alignment Sighting (COAS) device and the overhead window and rendezvous radar sensor information available to him from an onboard display. This model will be used in a flight analysis simulator to perform studies requiring a large number of runs, each of which currently needs an engineer in the loop to supply the piloting decisions. This work has much broader implications in control of robots such as the Flight Telerobotic Servicer, in automated pilot control and attitude control, and in advisory and evaluation functions that could be used for flight data monitoring or for testing of various rule sets in flight preparation.

Lea, Robert N.; Mitchell, Eric V.; Goodwin, Mary Ann

1987-01-01

150

An autonomous rendezvous and docking system using cruise missile technologies  

NASA Technical Reports Server (NTRS)

In November 1990 the Autonomous Rendezvous & Docking (AR&D) system was first demonstrated for members of NASA's Strategic Avionics Technology Working Group. This simulation utilized prototype hardware from the Cruise Missile and Advanced Centaur Avionics systems. The object was to show that all the accuracy, reliability and operational requirements established for a space craft to dock with Space Station Freedom could be met by the proposed system. The rapid prototyping capabilities of the Advanced Avionics Systems Development Laboratory were used to evaluate the proposed system in a real time, hardware in the loop simulation of the rendezvous and docking reference mission. The simulation permits manual, supervised automatic and fully autonomous operations to be evaluated. It is also being upgraded to be able to test an Autonomous Approach and Landing (AA&L) system. The AA&L and AR&D systems are very similar. Both use inertial guidance and control systems supplemented by GPS. Both use an Image Processing System (IPS), for target recognition and tracking. The IPS includes a general purpose multiprocessor computer and a selected suite of sensors that will provide the required relative position and orientation data. Graphic displays can also be generated by the computer, providing the astronaut / operator with real-time guidance and navigation data with enhanced video or sensor imagery.

Jones, Ruel Edwin

1991-01-01

151

Optimal two-impulse rendezvous with terminal tangent burn considering the trajectory constraints  

NASA Astrophysics Data System (ADS)

The two-impulse orbital rendezvous problem with a terminal tangent burn between coplanar elliptical orbits is studied by considering a lower bound on perigee radius and an upper bound on apogee radius for the transfer orbit. This problem requires that two spacecraft arrive at the rendezvous point with the same arrival flight-path angle after the same flight time. The admissible range of the final true anomaly that meets the perigee and apogee constraints is obtained in closed form. The revolution number of the transfer orbit is expressed as a function of the true anomaly and the revolution numbers of the initial and final orbits. All the feasible solutions are obtained with a bound on the revolution number of the final orbit. Then, the minimum-fuel one is determined by comparing their costs. Finally, two numerical examples are provided to obtain all the feasible solutions for given initial impulse points and the optimal solution with the initial coasting arc. Numerical results show that the minimum-fuel solution for the terminal tangent burn rendezvous is close to that for the cotangent rendezvous when the rendezvous time is long enough; however, the cotangent rendezvous may not exist when the rendezvous time is short.

Xie, Chengqing; Zhang, Gang; Zhang, Yingchun; Li, Huayi

2014-08-01

152

Gossip-Based Solutions for Discrete Rendezvous in Populations of Communicating Agents  

PubMed Central

The objective of the rendezvous problem is to construct a method that enables a population of agents to agree on a spatial (and possibly temporal) meeting location. We introduce the buffered gossip algorithm as a general solution to the rendezvous problem in a discrete domain with direct communication between decentralized agents. We compare the performance of the buffered gossip algorithm against the well known uniform gossip algorithm. We believe that a buffered solution is preferable to an unbuffered solution, such as the uniform gossip algorithm, because the use of a buffer allows an agent to use multiple information sources when determining its desired rendezvous point, and that access to multiple information sources may improve agent decision making by reinforcing or contradicting an initial choice. To show that the buffered gossip algorithm is an actual solution for the rendezvous problem, we construct a theoretical proof of convergence and derive the conditions under which the buffered gossip algorithm is guaranteed to produce a consensus on rendezvous location. We use these results to verify that the uniform gossip algorithm also solves the rendezvous problem. We then use a multi-agent simulation to conduct a series of simulation experiments to compare the performance between the buffered and uniform gossip algorithms. Our results suggest that the buffered gossip algorithm can solve the rendezvous problem faster than the uniform gossip algorithm; however, the relative performance between these two solutions depends on the specific constraints of the problem and the parameters of the buffered gossip algorithm. PMID:25397882

Hollander, Christopher D.; Wu, Annie S.

2014-01-01

153

Short profile for the human spacecraft Soyuz-TMA rendezvous mission to the ISS?  

NASA Astrophysics Data System (ADS)

Reduction of flight duration after insertion till docking to the ISS is considered. In the beginning of the human flight era both the USSR and the USA used short mission profiles due to limited life support resources. A rendezvous during these missions was usually achieved in 1-5 revolutions. The short-term rendezvous were made possible by the coordinated launch profiles of both rendezvousing spacecraft, which provided specific relative position of the spacecraft or phase angle conditions. After the beginning of regular flights to the orbital stations these requirements became difficult to fulfill. That is why it was decided to transfer to 1- or 2-day rendezvous profile. The long stay of a crew in a limited habitation volume of the Soyuz-TMA spacecraft before docking to the ISS is one of the most strained parts of the flight and naturally cosmonauts wish to dock to the ISS as soon as possible. As a result of previous studies the short four-burn rendezvous mission profile with docking in a few orbits was developed. It is shown that the current capabilities of the Soyuz-FG launch vehicle and the Soyuz-TMA spacecraft are sufficient to provide for that. The first test of the short rendezvous mission during Progress cargo vehicle flight to the ISS is planned for 2012. Possible contingencies pertinent to this profile are described. In particular, in the majority of the emergency cases there is a possibility of an urgent transfer to the present 2-day rendezvous profile. Thus, the short mission will be very flexible and will not influence the ISS mission plan. Fuel consumption for the nominal and emergency cases is defined by statistical simulation of the rendezvous mission. The qualitative analysis of the short-term and current 2-day rendezvous missions is performed.

Murtazin, Rafail; Petrov, Nikolay

2012-08-01

154

Real-time simulations for automated rendezvous and capture  

NASA Technical Reports Server (NTRS)

Although the individual technologies for automated rendezvous and capture (AR&C) exist, they have not yet been integrated to produce a working system in the United States. Thus, real-time integrated systems simulations are critical to the development and pre-flight demonstration of an AR&C capability. Real-time simulations require a level of development more typical of a flight system compared to purely analytical methods, thus providing confidence in derived design concepts. This presentation will describe Martin Marietta's Space Operations Simulation (SOS) Laboratory, a state-of-the-art real-time simulation facility for AR&C, along with an implementation for the Satellite Servicer System (SSS) Program.

Cuseo, John A.

1991-01-01

155

NASA Automated Rendezvous and Capture Review. Executive summary  

NASA Technical Reports Server (NTRS)

In support of the Cargo Transfer Vehicle (CTV) Definition Studies in FY-92, the Advanced Program Development division of the Office of Space Flight at NASA Headquarters conducted an evaluation and review of the United States capabilities and state-of-the-art in Automated Rendezvous and Capture (AR&C). This review was held in Williamsburg, Virginia on 19-21 Nov. 1991 and included over 120 attendees from U.S. government organizations, industries, and universities. One hundred abstracts were submitted to the organizing committee for consideration. Forty-two were selected for presentation. The review was structured to include five technical sessions. Forty-two papers addressed topics in the five categories below: (1) hardware systems and components; (2) software systems; (3) integrated systems; (4) operations; and (5) supporting infrastructure.

1991-01-01

156

Near Earth Asteroid Rendezvous (NEAR) Spacecraft/Delta II launch  

NASA Technical Reports Server (NTRS)

The Near Earth Asteroid Rendezvous (NEAR) spacecraft undergoing preflight preparation in the Spacecraft Assembly Encapsulation Facility-2 (SAEF-2) at Kennedy Space Center (KSC). NEAR will perform two critical mission events - Mathilde flyby and the Deep-Space maneuver. NEAR will fly-by Mathilde, a 38-mile (61-km) diameter C-type asteroid, making use of its imaging system to obtain useful optical navigation images. The primary science instrument will be the camera, but measurements of magnetic fields and mass also will be made. The Deep-Space Maneuver (DSM) will be executed about a week after the Mathilde fly-by. The DSM represents the first of two major burns during the NEAR mission of the 100-pound bi-propellant (Hydrazine/nitrogen tetroxide) thruster. This maneuver is necessary to lower the perihelion distance of NEAR's trajectory. The DSM will be conducted in two segments to minimize the possibility of an overburn situation.

1996-01-01

157

STS 63 Flight Day 4 Highlights/MIR-Shuttle Rendezvous  

NASA Technical Reports Server (NTRS)

STS 63 Flight, day 4, the MIR-Shuttle rendezvous is highlighted in this video. The six-member team in the Shuttle are introduced and discuss their functions and tests for this day of the flight. There is actual footage of earth from space, of the MIR Space Station, a tour of the Shuttle cockpit, some footage from the MIR of the Space Shuttle, and footage from inside the MIR with the cosmonauts. Mission control communications with the Shuttle, communication between the Shuttle and MIR, and an historic communication between the Shuttle's astronauts and President Bill Clinton are included. President Clinton interviews each of the six-member team and discusses the upcoming space walk by Dr. Bernard Harris, the first black astronaut to walk in space. This video was recorded on February 6, 1995.

1995-01-01

158

STS 63 flight day 4 highlights/MIR-Shuttle rendezvous  

NASA Astrophysics Data System (ADS)

STS 63 Flight, day 4, the MIR-Shuttle rendezvous is highlighted in this video. The six-member team in the Shuttle are introduced and discuss their functions and tests for this day of the flight. There is actual footage of earth from space, of the MIR Space Station, a tour of the Shuttle cockpit, some footage from the MIR of the Space Shuttle, and footage from inside the MIR with the cosmonauts. Mission control communications with the Shuttle, communication between the Shuttle and MIR, and an historic communication between the Shuttle's astronauts and President Bill Clinton are included. President Clinton interviews each of the six-member team and discusses the upcoming space walk by Dr. Bernard Harris, the first black astronaut to walk in space. This video was recorded on February 6, 1995.

1995-02-01

159

Differential drag spacecraft rendezvous using an adaptive Lyapunov control strategy  

NASA Astrophysics Data System (ADS)

This paper introduces a novel Lyapunov-based adaptive control strategy for spacecraft maneuvers using atmospheric differential drag. The control forces required for rendezvous maneuvers at low Earth orbits can be generated by varying the aerodynamic drag affecting each spacecraft. This can be accomplished, for example, by rotating dedicated sets of drag panels. Thus, the relative spacecraft motion can be controlled without using any propellant since the motion of the panels can be powered by solar energy. A novel adaptive Lyapunov controller is designed, and a critical value for the relative drag acceleration that ensures Lyapunov stability is found. The critical value is used to adapt the Lyapunov controller, enhancing its performance. The method is validated using simulations. The results show that the Adaptive Lyapunov technique outperforms previous control strategies for differential drag based spacecraft maneuvering.

Pérez, David; Bevilacqua, Riccardo

2013-02-01

160

Orion Rendezvous, Proximity Operations, and Docking Design and Analysis  

NASA Technical Reports Server (NTRS)

The Orion vehicle will be required to perform rendezvous, proximity operations, and docking with the International Space Station (ISS) and the Earth Departure Stage (EDS)/Lunar Landing Vehicle (LLV) stack in Low Earth Orbit (LEO) as well as with the Lunar Landing Vehicle in Low Lunar Orbit (LLO). The RPOD system, which consists of sensors, actuators, and software is being designed to be flexible and robust enough to perform RPOD with different vehicles in different environments. This paper will describe the design and the analysis which has been performed to date to allow the vehicle to perform its mission. Since the RPOD design touches on many areas such as sensors selection and placement, trajectory design, navigation performance, and effector performance, it is inherently a systems design problem. This paper will address each of these issues in order to demonstrate how the Orion RPOD has been designed to accommodate and meet all the requirements levied on the system.

D'Souza, Christopher; Hanak, F. Chad; Spehar, Pete; Clark, Fred D.; Jackson, Mark

2007-01-01

161

Rendezvous, proximity operations and capture quality function deployment report  

NASA Astrophysics Data System (ADS)

Rendezvous, Proximity Operations, and Capture (RPOC) is a missions operations area which is extremely important to present and future space initiatives and must be well planned and coordinated. To support this, a study team was formed to identify a specific plan of action using the Quality Function Deployment (QFD) process. This team was composed of members from a wide spectrum of engineering and operations organizations which are involved in the RPOC technology area. The key to this study's success is an understanding of the needs of potential programmatic customers and the technology base available for system implementation. To this end, the study team conducted interviews with a variety of near term and future programmatic customers and technology development sponsors. The QFD activity led to a thorough understanding of the needs of these customers in the RPOC area, as well as the relative importance of these needs.

Lamkin, Stephen L.

1991-12-01

162

Mission opportunity maps for rendezvous with earth-crossing asteroids  

NASA Technical Reports Server (NTRS)

Rendezvous missions for earth-crossing asteroids are of interest to NASA, for scientific purposes as well as for technological applications and ecological implications. To provide a comprehensive data base for planners of such missions, a mission opportunity map (MOM) has been created for eight relatively easy-to-access asteroids. A MOM presents such mission data as launch dates, flight times, and launch and postlaunch delta-V requirements for all useful mission opportunities. The merits of a MOM are: (1) searches for all useful mission opportunities are completed in the process of generating a MOM, and (2) a clear view of good and bad opportunities, the extent of performance variations, and the repeatability of the missions.

Yen, C.-W. L.

1984-01-01

163

Mission opportunity maps for rendezvous with earth-crossing asteroids  

NASA Technical Reports Server (NTRS)

Rendezvous missions to earth-crossing asteroids are of interest to NASA, for scientific purposes as well as for technological applications and ecological implications. To provide a comprehensive data base for planners of such missions, a mission opportunity map (MOM) has been created for eight relatively easy-to-access asteroids. A MOM presents such mission data as launch dates, flight times, and launch and postlaunch delta V requirements for all useful mission opportunities. The merits of a MOM are: (1) searches for all useful mission oportunities are completed in the process of generating a MOM, and (2) a MOM provides a clear view of good and bad opportunities, the extent of performance variations, and the repeatability of the missions.

Yen, Chen-Wan L.

1989-01-01

164

Rendezvous Integration Complexities of NASA Human Flight Vehicles  

NASA Technical Reports Server (NTRS)

Propellant-optimal trajectories, relative sensors and navigation, and docking/capture mechanisms are rendezvous disciplines that receive much attention in the technical literature. However, other areas must be considered. These include absolute navigation, maneuver targeting, attitude control, power generation, software development and verification, redundancy management, thermal control, avionics integration, robotics, communications, lighting, human factors, crew timeline, procedure development, orbital debris risk mitigation, structures, plume impingement, logistics, and in some cases extravehicular activity. While current and future spaceflight programs will introduce new technologies and operations concepts, the complexity of integrating multiple systems on multiple spacecraft will remain. The systems integration task may become more difficult as increasingly complex software is used to meet current and future automation, autonomy, and robotic operation requirements.

Brazzel, Jack P.; Goodman, John L.

2009-01-01

165

The comet rendezvous asteroid flyby mission: A status report  

NASA Technical Reports Server (NTRS)

The Comet Rendezvous Asteroid Flyby (CRAF) mission received a new start in fiscal year 1990. CRAF will match orbits with an active short-period comet and follow it around the Sun, making scientific measurements of the nucleus, coma, and tail. The Imaging system will map the nucleus surface at a resolution of 1 meter/line-pair or better, while Visible and Infrared Mapping Spectrometer (VIMS) and Thermal Infrared Radiometer Experiment (TIREX) will produce spectral and thermal maps of the surface. Onboard instruments will collect cometary dust, ice, and gases and perform elemental and molecular analysis. A suite of fields and particles instruments will observe the solar wind interaction with the cometary atmosphere and tail. Radio tracking of the spacecraft will provide an accurate measure of the nucleus mass and higher harmonics in the comet's gravity field. En route to the comet, the spacecraft will make a close flyby of a large asteroid, preferably a primitive type from the outer main belt. Observations at the asteroid include remote sensing mapping of the surface, detection of any solar wind interaction observable at the flyby distance, and measurement of the asteroid mass to better than 10 percent accuracy. Detailed design of the CRAF spacecraft is currently underway at the Jet Propulsion Laboratory (JPL). Recent mass growth has necessitated a switch to Venus-Earth gravity assist type trajectories, similar to that used by the Galileo spacecraft. These trajectories require longer flight times from launch to rendezvous with the target comet. The details of the current baseline mission, spacecraft design, and instrument payload will be reviewed.

Weissman, Paul R.; Neugebauer, Marcia

1991-01-01

166

STS-41 MS Akers tumbles out of JSC's CCT during egress exercises  

NASA Technical Reports Server (NTRS)

STS-41 Mission Specialist (MS) Thomas D. Akers, wearing a launch and entry suit (LES) and launch and entry helmet (LEH), tumbles out of JSC's crew compartment trainer (CCT) during side hatch emergency egress exercises. Using the crew escape system (CES) pole, Akers simulated the procedures necessary to bailout of the Shuttle during the ascent phase. A technician assists Akers, rolling across an inflated safety pad, as a second technician looks on. In the open side hatch, another crewmember prepares for egress.

1990-01-01

167

Predicting the overall specific energy requirement of crushing, high pressure grinding roll and tumbling mill circuits  

Microsoft Academic Search

In a previous paper [Morrell, S. 2008a. A method for predicting the specific energy requirement of comminution circuits and assessing their energy utilisation efficiency. Minerals Engineering 21(3), 5–9] an approach was described which enabled the specific energy of tumbling mills such as Autogenous (AG), Semi-autogenous (SAG) and ball mills to be estimated from laboratory-derived ore characterisation data. The following paper

S. Morrell

2009-01-01

168

Accuracy Analysis for Automatic Orientation of a Tumbling Oblique Viewing Sensor System  

NASA Astrophysics Data System (ADS)

Dynamic camera systems with moving parts are difficult to handle in photogrammetric workflow, because it is not ensured that the dynamics are constant over the recording period. Minimum changes of the camera's orientation greatly influence the projection of oblique images. In this publication these effects - originating from the kinematic chain of a dynamic camera system - are analysed and validated. A member of the Modular Airborne Camera System family - MACS-TumbleCam - consisting of a vertical viewing and a tumbling oblique camera was used for this investigation. Focus is on dynamic geometric modeling and the stability of the kinematic chain. To validate the experimental findings, the determined parameters are applied to the exterior orientation of an actual aerial image acquisition campaign using MACS-TumbleCam. The quality of the parameters is sufficient for direct georeferencing of oblique image data from the orientation information of a synchronously captured vertical image dataset. Relative accuracy for the oblique data set ranges from 1.5 pixels when using all images of the image block to 0.3 pixels when using only adjacent images.

Stebner, K.; Wieden, A.

2014-03-01

169

An application of linear covariance analysis to the design of responsive near-rendezvous missions  

E-print Network

This thesis investigates a new class of launch vehicles capable of being released from an aircraft which ultimately have the goal of achieving near-rendezvous conditions at orbital altitudes up to 800 km. These launch ...

Visser, Benjamin Lee

2007-01-01

170

A vision based control system for autonomous rendezvous and capture of a Mars Orbital Sample  

E-print Network

NASA's Mars Sample Return (MSR) mission involves many challenging operations. The current mission scenario utilizes a small Orbiting Sample (OS) satellite, launched from the surface of Mars, which will rendezvous with an ...

Jyothindran, Vishnu

2013-01-01

171

Methodology for prototyping increased levels of automation for spacecraft rendezvous functions  

E-print Network

The Crew Exploration Vehicle (CEV) necessitates higher levels of automation than previous NASA vehicles due to program requirements for automation, including Automated Rendezvous and Docking (AR&D). Studies of spacecraft development often point...

Hart, Jeremy Jay

2009-05-15

172

Avionics and control system development for mid-air rendezvous of two unmanned aerial vehicles  

E-print Network

A flight control system was developed to achieve mid-air rendezvous of two unmanned aerial vehicles (UAVs) as a part of the Parent Child Unmanned Aerial Vehicle (PCUAV) project at MIT and the Draper Laboratory. A lateral ...

Park, Sanghyuk, 1973-

2004-01-01

173

A feasibility study of unmanned rendezvous and docking in Mars orbit: Midterm review  

NASA Technical Reports Server (NTRS)

The ascent, rendezvous, docking and sample transfer operations in a potential MSSR mission that uses the Mars orbital rendezvous mode are considered. In order that the design choices made for these operations remain compatible with the rest of the mission, the impact on the Earth launch, Mars landing and orbiting and Earth return phase are also being assessed. The selection and description of a preliminary baseline concept are presented.

1974-01-01

174

On Torque and Tumbling in Swimming Escherichia coli  

Microsoft Academic Search

Bacteria swim by rotating long thin helical filaments, each driven at its base by a reversible rotary motor. When the motors of peritrichous cells turn counterclockwise (CCW), their filaments form bundles that drive the cells forward. We imaged fluorescently labeled cells of Escherichia coli with a high-speed charge-coupled- device camera (500 frames\\/s) and measured swimming speeds, rotation rates of cell

Nicholas C. Darnton; Linda Turner; Svetlana Rojevsky; Howard C. Berg

2007-01-01

175

Sodium chloride concentration affects yield, quality, and sensory acceptability of vacuum-tumbled marinated broiler breast fillets.  

PubMed

The objective of this experiment was to determine the effect of sodium chloride concentration on yield, instrumental quality, and sensory acceptability of broiler breast meat that was vacuum tumbled with a 15% solution (over green weight) for 30 min. Different concentrations (0, 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50%) of NaCl (salt) and 0.35% sodium tripolyphosphate were included in the marinade solution. After marinating, breast fillets were evaluated for marination yields, pH, surface color, cooking loss, tenderness, expressible moisture, proximate composition, purge loss, sodium content, and sensory acceptability. As salt concentration increased, CIE L* decreased linearly, with a concentration of 0.75% having lower (P < 0.05) CIE L* values when compared with the control, 0, and 0.25% NaCl treatments. In addition, there was a linear and quadratic decrease (P < 0.05) in shear force as salt concentration increased, with no further decrease (P < 0.05) when greater than 0.75% NaCl was used. Cooking yield increased (P < 0.05) as the salt concentration increased to 1.0%. All marinated treatments were preferred (P < 0.05) over the control treatment, and all treatments marinated with at least 0.50% sodium chloride had an average rating of like moderately. Cluster analysis indicated that consumer groups varied in their preference of broiler breast meat treatments and that samples that were marinated with between 0.5 to 1.0% NaCl were acceptable to the majority of consumers. Marination with 0.75% NaCl was sufficient to maximize yields and decrease lightness (L*) in vacuum-tumbled, marinated broiler breast that is sold raw, but 1.0% NaCl could be used in a precooked product because it minimizes cook loss. In addition, use of 0.50% NaCl had minimal effects on yields, color, and sensory acceptability when compared with products that were marinated with greater concentrations of NaCl. PMID:22499878

Lopez, K; Schilling, M W; Armstrong, T W; Smith, B S; Corzo, A

2012-05-01

176

Autonomous Mission Manager for Rendezvous, Inspection and Mating  

NASA Technical Reports Server (NTRS)

To meet cost and safety objectives, space missions that involve proximity operations between two vehicles require a high level of autonomy to successfully complete their missions. The need for autonomy is primarily driven by the need to conduct complex operations outside of communication windows, and the communication time delays inherent in space missions. Autonomy also supports the goals of both NASA and the DOD to make space operations more routine, and lower operational costs by reducing the requirement for ground personnel. NASA and the DoD have several programs underway that require a much higher level of autonomy for space vehicles. NASA's Space Launch Initiative (SLI) program has ambitious goals of reducing costs by a factor or 10 and improving safety by a factor of 100. DARPA has recently begun its Orbital Express to demonstrate key technologies to make satellite servicing routine. The Air Force's XSS-ll program is developing a protoflight demonstration of an autonomous satellite inspector. A common element in space operations for many NASA and DOD missions is the ability to rendezvous, inspect anclJor dock with another spacecraft. For DARPA, this is required to service or refuel military satellites. For the Air Force, this is required to inspect un-cooperative resident space objects. For NASA, this is needed to meet the primary SLI design reference mission of International Space Station re-supply. A common aspect for each of these programs is an Autonomous Mission Manager that provides highly autonomous planning, execution and monitoring of the rendezvous, inspection and docking operations. This paper provides an overview of the Autonomous Mission Manager (AMM) design being incorporated into many of these technology programs. This AMM provides a highly scalable level of autonomous operations, ranging from automatic execution of ground-derived plans to highly autonomous onboard planning to meet ground developed mission goals. The AMM provides the capability to automatically execute the plans and monitor the system performance. In the event of system dispersions or failures the AMM can modify plans or abort to assure overall system safety. This paper describes the design and functionality of Draper's AMM framework, presents concept of operations associated with the use of the AMM, and outlines the relevant features of the flight demonstrations.

Zimpfer, Douglas J.

2003-01-01

177

The Successful Development of an Automated Rendezvous and Capture (AR&C) System for the National Aeronautics and Space Administration  

Microsoft Academic Search

During the 1990’s, the Marshall Space Flight Center (MSFC) conducted pioneering research in the development of an automated rendezvous and capture\\/docking (AR&C) system for U.S. space vehicles. Development and demonstration of a rendezvous sensor was identified early in the AR&C Program as the critical enabling technology that allows automated proximity operations and docking. A first generation rendezvous sensor, the Video

Fred D. Roe; Richard T. Howard

2003-01-01

178

The Successful Development of an Automated Rendezvous and Capture (AR&C) System for the National Aeronautics and Space Administration  

Microsoft Academic Search

During the 1990's, the Marshall Space Flight Center (MSFC) conducted pioneering research in the development of an automated rendezvous and capture\\/docking (AR&C) system for U.S. space vehicles. Development and demonstration of a rendezvous sensor was identified early in the AR&C Program as the critical enabling technology that allows automated proximity operations and docking. A first generation rendezvous sensor, the Video

Fred D. Roe; Richard T. Howard

2003-01-01

179

Multi-sensor Testing for Automated Rendezvous and Docking  

NASA Technical Reports Server (NTRS)

During the past two years, many sensors have been tested in an open-loop fashion in the Marshall Space Flight Center (MSFC) Flight Robotics Laboratory (FRL) to both determine their suitability for use in Automated Rendezvous and Docking (AR&D) systems and to ensure the test facility is prepared for future multi-sensor testing. The primary focus of this work was in support of the CEV AR&D system, because the AR&D sensor technology area was identified as one of the top risks in the program. In 2006, four different sensors were tested individually or in a pair in the MSFC FRL. In 2007, four sensors, two each of two different types, were tested simultaneously. In each set of tests, the target was moved through a series of pre-planned trajectories while the sensor tracked it. In addition, a laser tracker "truth" sensor also measured the target motion. The tests demonstrated the functionality of testing four sensors simultaneously as well as the capabilities (both good and bad) of all of the different sensors tested. This paper outlines the test setup and conditions, briefly describes the facility, summarizes the earlier results of the individual sensor tests, and describes in some detail the results of the four-sensor testing. Post-test analysis includes data fusion by minimum variance estimation and sequential Kalman filtering. This Sensor Technology Project work was funded by NASA's Exploration Technology Development Program.

Howard, Richard T.; Carrington, Connie K.

2008-01-01

180

Observer-based body-frame hovering control over a tumbling asteroid  

NASA Astrophysics Data System (ADS)

Observer-based hovering control over a tumbling asteroid in the body-fixed frame is studied. An extended Kalman filter (EKF) is used to process range measurements from a small collection of ground stations, yielding estimates of the spacecraft state vector and the gravitational parameters of the asteroid assuming a second degree and order gravity field model. The estimated states are used in the optimal feedback control algorithm which consists of two alternatives: time-varying LQR or the Lyapunov-Floquet transformation (LFT) and time-invariant LQR. The closed-loop response of the system and the control effort required are investigated and compared for both control strategies.

Nazari, Morad; Wauson, Robert; Critz, Thomas; Butcher, Eric A.; Scheeres, Daniel J.

2014-09-01

181

Integrated GPS/INS navigation system design for autonomous spacecraft rendezvous  

NASA Astrophysics Data System (ADS)

The goal of the NASA Space Launch Initiative (SLI) program is to advance the technologies for the next generation reusable launch vehicle (RLV). The SLI program has identified automated rendezvous and docking as an area requiring further research and development. Currently, the Space Shuttle uses a partially manual system for rendezvous, but a fully automated system could be safer and more reliable. Previous studies have shown that it is feasible to use the Global Positioning System (GPS) for spacecraft navigation during rendezvous with the International Space Station (ISS). However, these studies have not accounted for the effects of GPS signal blockage and multipath in the vicinity of the ISS, which make a GPS-only navigation system less accurate and reliable. One possible solution is to combine GPS with an inertial navigation system (INS). The integration of GPS and INS can be achieved using a Kalman filter. GPS/INS systems have been used in aircraft for many years and have also been used in launch vehicles. However, the performance of GPS/INS systems in orbit and during spacecraft rendezvous has not been characterized. The primary objective of this research is to evaluate the ability of an integrated GPS/INS to provide accurate navigation solutions during a rendezvous scenario where the effects of ISS signal blockage, multipath and delta-v maneuvers degrade GPS-only navigation. In order to accomplish this, GPS-only and GPS/INS Kalman filters have been developed for both absolute and relative navigation, as well as a new statistical multipath model for spacecraft operating near the ISS. Several factors that affect relative navigation performance were studied, including: filter tuning, GPS constellation geometry, rendezvous approach direction, and inertial sensor performance. The results showed that each of these factors has a large impact on relative navigation performance. Finally, it has been demonstrated that a GPS/INS system based on medium accuracy aircraft avionics-grade inertial sensors does not provide adequate relative navigation performance for rendezvous with the ISS unless accelerometer thresholding is used. However, the use of state-of-the-art inertial navigation sensors provides relative position accuracy which is adequate for rendezvous with ISS if an additional rendezvous sensor is included.

Gaylor, David Edward

2003-10-01

182

Flight data results of estimate fusion for spacecraft rendezvous navigation from shuttle mission STS-69  

NASA Technical Reports Server (NTRS)

A recently developed rendezvous navigation fusion filter that optimally exploits existing distributed filters for rendezvous and GPS navigation to achieve the relative and inertial state accuracies of both in a global solution is utilized here to process actual flight data. Space Shuttle Mission STS-69 was the first mission to date which gathered data from both the rendezvous and Global Positioning System filters allowing, for the first time, a test of the fusion algorithm with real flight data. Furthermore, a precise best estimate of trajectory is available for portions of STS-69, making possible a check on the performance of the fusion filter. In order to successfully carry out this experiment with flight data, two extensions to the existing scheme were necessary: a fusion edit test based on differences between the filter state vectors, and an underweighting scheme to accommodate the suboptimal perfect target assumption made by the Shuttle rendezvous filter. With these innovations, the flight data was successfully fused from playbacks of downlinked and/or recorded measurement data through ground analysis versions of the Shuttle rendezvous filter and a GPS filter developed for another experiment. The fusion results agree with the best estimate of trajectory at approximately the levels of uncertainty expected from the fusion filter's covariance matrix.

Carpenter, J. Russell; Bishop, Robert H.

1996-01-01

183

Manned maneuvering unit applications for automated rendezvous and capture  

NASA Astrophysics Data System (ADS)

Automated Rendezvous and Capture (AR&C) is an important technology to multiple National Aeronautics and Space Administration (NASA) programs and centers. The recent Johnson Spacecraft Center (JSC) AR&C Quality Function Deployment (QFD) has listed on-orbit demonstration of related technologies as a near term priority. Martin Marietta has been evaluating use of the Manned Maneuvering Unit (MMU) for a low cost near term on-orbit demonstration of AR&C technologies such as control algorithms, sensors, and processors as well as system level performance. The MMU Program began in 1979 as the method of repairing the Space Shuttle (STS) Thermal Protection System (the tiles). The units were not needed for this task, but were successfully employed during three Shuttle flights in 1984: a test flight was flown in in February as proof of concept, in April the MMU participated in the Solar Max Repair Mission, and in November the MMU's returned to space to successfully rescue the two errant satellites, Westar and Palapa. In the intervening years, the MMU simulator and MMU Qualification Test Unit (QTU) have been used for Astronaut training and experimental evaluations. The Extra-Vehicular Activities (EVA) Retriever has used the QTU, in an unmanned form, as a free-flyer on the Johnson Space Center (JSC) Precision Air Bearing Floor (PABF). Currently, the MMU is undergoing recertification for flight. The two flight units were removed from storage in September, 1991 and evaluation tests were performed. The tests demonstrated that the units are in good shape with no discrepancies that would preclude further use. The Return to Flight effort is currently clearing up recertification issues and evaluating the design against the present Shuttle environments.

Brehm, Donald L.; Cuseo, John A.; Lenda, Joseph A.; Ray, Lex; Whitsett, C. Edward

184

Manned maneuvering unit applications for automated rendezvous and capture  

NASA Technical Reports Server (NTRS)

Automated Rendezvous and Capture (AR&C) is an important technology to multiple National Aeronautics and Space Administration (NASA) programs and centers. The recent Johnson Spacecraft Center (JSC) AR&C Quality Function Deployment (QFD) has listed on-orbit demonstration of related technologies as a near term priority. Martin Marietta has been evaluating use of the Manned Maneuvering Unit (MMU) for a low cost near term on-orbit demonstration of AR&C technologies such as control algorithms, sensors, and processors as well as system level performance. The MMU Program began in 1979 as the method of repairing the Space Shuttle (STS) Thermal Protection System (the tiles). The units were not needed for this task, but were successfully employed during three Shuttle flights in 1984: a test flight was flown in in February as proof of concept, in April the MMU participated in the Solar Max Repair Mission, and in November the MMU's returned to space to successfully rescue the two errant satellites, Westar and Palapa. In the intervening years, the MMU simulator and MMU Qualification Test Unit (QTU) have been used for Astronaut training and experimental evaluations. The Extra-Vehicular Activities (EVA) Retriever has used the QTU, in an unmanned form, as a free-flyer on the Johnson Space Center (JSC) Precision Air Bearing Floor (PABF). Currently, the MMU is undergoing recertification for flight. The two flight units were removed from storage in September, 1991 and evaluation tests were performed. The tests demonstrated that the units are in good shape with no discrepancies that would preclude further use. The Return to Flight effort is currently clearing up recertification issues and evaluating the design against the present Shuttle environments.

Brehm, Donald L.; Cuseo, John A.; Lenda, Joseph A.; Ray, Lex; Whitsett, C. Edward

1991-01-01

185

WARPS AND BARS FROM THE EXTERNAL TIDAL TORQUES OF TUMBLING DARK HALOS  

SciTech Connect

The dark matter halos in LAMBDA cold dark matter cosmological simulations are triaxial and highly flattened. In many cases, these triaxial equilibria are also tumbling slowly, typically about their short axes, with periods of order a Hubble time. Halos may therefore exert a slowly changing external torque on spiral galaxies that can affect their dynamical evolution in interesting ways. We examine the effect of the external torques exerted by a tumbling quadrupolar tidal field on the evolution of spiral galaxies using N-body simulations with realistic, disk galaxy models. We measure the amplitude of the external quadrupole moments of dark halos in cosmological simulations and use these to force disk galaxy models in a series of N-body experiments for a range of pattern speeds. We find that the torques are strong enough to induce long-lived transient warps in disks similar to those observed in real spirals and also induce the bar instability at later times in some galaxy models that are otherwise stable for long periods of time in isolation. We also observe forced spiral structure near the edge of the disk where normally self gravity is too weak to be responsible for such a structure. This overlooked influence of dark halos may well be responsible for many of the peculiar aspects of disk galaxy dynamics.

Dubinski, John [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Chakrabarty, Dalia, E-mail: dubinski@astro.utoronto.c, E-mail: dalia.chakrabarty@nottingham.ac.u [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2009-10-01

186

Prediction of flow-aligning and tumbling in a bent-core nematic liquid crystal using measurements of orienation order parameters  

NASA Astrophysics Data System (ADS)

The flow behavior of bent-core nematic liquid crystal (A131), which has been known to exhibit a biaxial nematic phase, is predicted by measurements of 2^nd and 4^th rank orientation order parameters. Using experimentally determined uniaxial, and , and biaxial orientation order parameters, , and from polarized micro-Raman spectroscopy, we compute the tumbling parameter, ?. The relationships between the order parameters and tumbling parameter derived by 2 different groups are used and the results are computed: a molecular theory by Archer and Larson (1995), that by Kroger and Seller (1995) for uniaxial system, and Leslie's theory for 2-director continuum. Temperature evolution of tumbling parameter shows the transition from a flow alignment regime to a tumbling instability. The results of the temperature evolution of tumbling parameter of bent-core nematic LC are compared to those of pure nematic LC (5CB) and LC mixture (E7).

Park, Min Sang; Park, Beom-Jin; Park, Jung Ok; Srinivasarao, Mohan

2010-03-01

187

An Assessment of the Technology of Automated Rendezvous and Capture in Space  

NASA Technical Reports Server (NTRS)

This paper presents the results of a study to assess the technology of automated rendezvous and capture (AR&C) in space. The outline of the paper is as follows. First, the history of manual and automated rendezvous and capture and rendezvous and dock is presented. Next, the need for AR&C in space is established. Then, today's technology and ongoing technology efforts related to AR&C in space are reviewed. In light of these, AR&C systems are proposed that meet NASA's future needs, but can be developed in a reasonable amount of time with a reasonable amount of money. Technology plans for developing these systems are presented; cost and schedule are included.

Polites, M. E.

1998-01-01

188

Interesting rendezvous location in a liver transplantation patient with anastomosis stricture  

PubMed Central

An endoscopic or radiologic percutaneous approach may be an initial minimally invasive method for treating biliary strictures after living donor liver transplantation; however, cannulation of biliary strictures is sometimes difficult due to the presence of a sharp or twisted angle within the stricture or a complete stricture. When an angulated or twisted biliary stricture interrupts passage of a guidewire over the stricture, it is difficult to replace the percutaneous biliary drainage catheter with inside stents by endoscopic retrograde cholangiopancreatography. The rendezvous technique can be used to overcome this difficulty. In addition to the classical rendezvous method, in cases with complete transection of the common bile duct a modified technique involving the insertion of a snare into the subhepatic space has been successfully performed. Herein, we report a modified rendezvous technique in the duodenal bulb as an extraordinary location for a patient with duct-to-duct anastomotic complete stricture after liver transplantation.

Odemis, Bulent; Oztas, Erkin; Yurdakul, Mehmet; Torun, Serkan; Suna, Nuredtin; Kayacetin, Ertugrul

2014-01-01

189

Time-fixed rendezvous by impulse factoring with an intermediate timing constraint. [for transfer orbits  

NASA Technical Reports Server (NTRS)

A method is presented for factoring a two-impulse orbital transfer into a three- or four-impulse transfer which solves the rendezvous problem and satisfies an intermediate timing constraint. Both the time of rendezvous and the intermediate time of a alinement are formulated as any element of a finite sequence of times. These times are integer multiples of a constant plus an additive constant. The rendezvous condition is an equality constraint, whereas the intermediate alinement is an inequality constraint. The two timing constraints are satisfied by factoring the impulses into collinear parts that vectorially sum to the original impulse and by varying the resultant period differences and the number of revolutions in each orbit. Five different types of solutions arise by considering factoring either or both of the two impulses into two or three parts with a limit for four total impulses. The impulse-factoring technique may be applied to any two-impulse transfer which has distinct orbital periods.

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

1974-01-01

190

Methodology for Developing a Probabilistic Risk Assessment Model of Spacecraft Rendezvous and Dockings  

NASA Technical Reports Server (NTRS)

In 2007 NASA was preparing to send two new visiting vehicles carrying logistics and propellant to the International Space Station (ISS). These new vehicles were the European Space Agency s (ESA) Automated Transfer Vehicle (ATV), the Jules Verne, and the Japanese Aerospace and Explorations Agency s (JAXA) H-II Transfer Vehicle (HTV). The ISS Program wanted to quantify the increased risk to the ISS from these visiting vehicles. At the time, only the Shuttle, the Soyuz, and the Progress vehicles rendezvoused and docked to the ISS. The increased risk to the ISS was from an increase in vehicle traffic, thereby, increasing the potential catastrophic collision during the rendezvous and the docking or berthing of the spacecraft to the ISS. A universal method of evaluating the risk of rendezvous and docking or berthing was created by the ISS s Risk Team to accommodate the increasing number of rendezvous and docking or berthing operations due to the increasing number of different spacecraft, as well as the future arrival of commercial spacecraft. Before the first docking attempt of ESA's ATV and JAXA's HTV to the ISS, a probabilistic risk model was developed to quantitatively calculate the risk of collision of each spacecraft with the ISS. The 5 rendezvous and docking risk models (Soyuz, Progress, Shuttle, ATV, and HTV) have been used to build and refine the modeling methodology for rendezvous and docking of spacecrafts. This risk modeling methodology will be NASA s basis for evaluating the addition of future ISS visiting spacecrafts hazards, including SpaceX s Dragon, Orbital Science s Cygnus, and NASA s own Orion spacecraft. This paper will describe the methodology used for developing a visiting vehicle risk model.

Farnham, Steven J., II; Garza, Joel, Jr.; Castillo, Theresa M.; Lutomski, Michael

2011-01-01

191

Monsters, magic and Mr Psycho: a biocultural approach to rough and tumble play in the early years of primary school  

Microsoft Academic Search

This paper focuses upon the developmental role of rough and tumble (R&T) play with particular attention to the narratives that children use to underpin such activities. A review of the literature suggests that current early years research and practice pays scant attention to children's outdoor free play activities. A piece of original research is described in which playtime activities were

Pam Jarvis

2007-01-01

192

Early Play Arousal, Sex-Typed Play, and Activity Level as Precursors to Later Rough-and-Tumble Play.  

ERIC Educational Resources Information Center

The extent of father's participation in rough-and-tumble (R&T) play with their children when the children were 18 months old, and children's early preferences for play sex-typed as boys' play, were related to levels of children's R&T play in first grade. (MDM)

McBride-Chang, Catherine; Jacklin, Carol Nagy

1993-01-01

193

Recent developments in electropolishing and tumbling R&D at Fermilab  

SciTech Connect

Fermi National Accelerator Lab (Fermilab) is continuing to improve its infrastructure for research and development on the processing of superconducting radio frequency cavities. A single cell 3.9 GHz electropolishing tool built at Fermilab and operated at an industrial partner was recently commissioned. The EP tool was used to produce a single cell 3.9 GHz cavity that reached an accelerating gradient of 30 MV/m with a quality factor of 5 x 10{sup 9}. A single cell 1.3 GHz cavity was also electropolished at the same industrial vendor using the vendor's vertical full-immersion technique. On their first and only attempt the vendor produced a single cell 1.3 GHz cavity that reached 30 MV/m with a quality factor of 1 x 10{sup 10}. These results will be detailed along with preliminary tumbling results.

Cooper, C.; Brandt, J.; Cooley, L.; Ge, M.; Harms, E.; Khabiboulline, T.; Ozelis, J.; /Fermilab; Boffo, C.; /Babcock Noell, Wuerzburg

2009-10-01

194

Electron Spin-Lattice Relaxation Mechanisms of Rapidly-Tumbling Nitroxide Radicals  

PubMed Central

Electron spin relaxation times at 295 K were measured at frequencies between 250 MHz and 34 GHz for perdeuterated 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (PDT) in five solvents with viscosities that result in tumbling correlation times, ?R, between 4 and 50 ps and for three 14N/15N pairs of nitroxides in water with ?R between 9 and 19 ps. To test the impact of structure on relaxation three additional nitroxides with ?R between 10 and 26 ps were studied. In this fast tumbling regime T2?1 ? T1?1 at frequencies up to about 9 GHz. At 34 GHz T2?1 > T1?1 due to increased contributions to T2?1 from incomplete motional averaging of g-anisotropy, and T2?1 ? T1?1 is proportional to ?R. The contribution to T1?1 from spin rotation is independent of frequency and decreases as ?R increases. Spin rotation dominates T1?1 at 34 GHz for all ?R studied, and at all frequencies studied for ?R = 4 ps. The contribution to T1?1 from modulation of nitrogen hyperfine anisotropy increases as frequency decreases and as ?R increases; it dominates at low frequencies for ?R > ? 15 ps. The contribution from modulation of g anisotropy is significant only at 34 GHz. Inclusion of a thermally-activated process was required to account for the observation that for most of the radicals, T1?1 was smaller at 250 MHz than at 1 to 2 GHz. The significant 15N/14N isotope effect, the small H/D isotope effect, and the viscosity dependence of the magnitude of the contribution from the thermally-activated process suggest that it arises from intramolecular motions of the nitroxide ring that modulate the isotropic A values. PMID:24056272

Biller, Joshua R.; Elajaili, Hanan; Meyer, Virginia; Rosen, Gerald M.; Eaton, Sandra S.; Eaton, Gareth R.

2013-01-01

195

Electron spin-lattice relaxation mechanisms of rapidly-tumbling nitroxide radicals.  

PubMed

Electron spin relaxation times at 295 K were measured at frequencies between 250 MHz and 34 GHz for perdeuterated 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (PDT) in five solvents with viscosities that result in tumbling correlation times, ?R, between 4 and 50 ps and for three (14)N/(15)N pairs of nitroxides in water with ?R between 9 and 19 ps. To test the impact of structure on relaxation three additional nitroxides with ?R between 10 and 26 ps were studied. In this fast tumbling regime T2(-1)~T1(-1) at frequencies up to about 9 GHz. At 34 GHz T2(-1)>T1(-1) due to increased contributions to T2(-1) from incomplete motional averaging of g-anisotropy, and T2(-1)-T1(-1) is proportional to ?R. The contribution to T1(-1) from spin rotation is independent of frequency and decreases as ?R increases. Spin rotation dominates T1(-1) at 34 GHz for all ?R studied, and at all frequencies studied for ?R=4 ps. The contribution to T1(-1) from modulation of nitrogen hyperfine anisotropy increases as frequency decreases and as ?R increases; it dominates at low frequencies for ?R>~15 ps. The contribution from modulation of g anisotropy is significant only at 34 GHz. Inclusion of a thermally-activated process was required to account for the observation that for most of the radicals, T1(-1) was smaller at 250 MHz than at 1-2 GHz. The significant (15)N/(14)N isotope effect, the small H/D isotope effect, and the viscosity dependence of the magnitude of the contribution from the thermally-activated process suggest that it arises from intramolecular motions of the nitroxide ring that modulate the isotropic A values. PMID:24056272

Biller, Joshua R; Elajaili, Hanan; Meyer, Virginia; Rosen, Gerald M; Eaton, Sandra S; Eaton, Gareth R

2013-11-01

196

Use of isotropically tumbling bicelles to measure curvature induced by membrane components.  

PubMed

Isotropically tumbling discoidal bicelles are a useful biophysical tool for the study of lipids and proteins by NMR, dynamic light scattering, and small-angle X-ray scattering. Isotropically tumbling bicelles present a low-curvature central region, typically enriched with DMPC in the lamellar state, and a highly curved detergent rim, typically composed of DHPC. In this report, we study the impact of the partitioning and induced curvature of a few molecules of a foreign lipid on the bicelle size, structure, and curvature. Previous approaches for studying curvature have focused on macroscopic and bulk properties of membrane curvature. In the approach presented here, we show that the conical shape of the DOPE lipid and the inverted-conical shape of the DPC lipid induce measurable curvature changes in the bicelle size. Bicelles with an average of 1.8 molecules of DOPE have marked increases in the size of bicelles, consistent with negative membrane curvature in the central region of the bicelle. With bicelle curvature models, radii of curvature on the order of -100 Ĺ and below are measured, with a greater degree of curvature observed in the more pliable L? state above the phase-transition temperature of DMPC. Bicelles with an average of 1.8 molecules of DPC are reduced in size, consistent with positive membrane curvature in the rim, and at higher temperatures, DPC is distributed in the central region to form mixed-micelle structures. We use translational and rotational diffusion measurements by NMR, size-exclusion chromatography, and structural models to quantitate changes in bicelle size, curvature, and lipid dynamics. PMID:25203267

Draney, Adrian W; Smrt, Sean T; Lorieau, Justin L

2014-10-01

197

Multi-agent rendezvous on street networks Malika Meghjani and Gregory Dudek  

E-print Network

them to meet (i.e. rendezvous) at some point during their travels. We propose an energy efficient other for load balancing, or when automated taxis need to load balance passengers. We propose are expressed by an actual traversability database for urban The authors are with the Centre for Intelligent

198

Precision spacecraft rendezvous using global positioning system: An integrated hardware approach  

Microsoft Academic Search

The objective of this dissertation is to develop a precision rendezvous methodology for Earth orbiting spacecraft utilizing the Global Positioning System (GPS). A GPS receiver is placed on each space vehicle and a communication link is used to pass GPS measurements from the target to the chaser spacecraft. The integrated navigation and guidance system resides on the chaser vehicle. The

Takuji Ebinuma

2001-01-01

199

Security-Enhanced Virtual Channel Rendezvous Algorithm for Dynamic Spectrum Access Wireless Networks  

Microsoft Academic Search

This paper presents the security-enhanced virtual channel rendezvous (SVCR) algorithm to improve the robustness of a dynamic spectrum access (DSA) network against attacks from power-constrained smart jammers. The jammer is smart in the sense that it senses and analyzes the spectrum activities of the DSA network before launching an attack. SVCR does not use a common control channel. In addition,

Liangping Ma; Chien-Chung Shen

2008-01-01

200

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

NASA Technical Reports Server (NTRS)

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

Kachmar, P. M.

1973-01-01

201

An analytic approach to optimal rendezvous using Clohessy-Wiltshire equations  

NASA Technical Reports Server (NTRS)

An analytic approach is used to obtain the optimal solution time that minimizes the sum of the two applied impulses necessary to rendezvous for the Clohessy-Wiltshire equations. A plume impingement inequality constraint on the solution is examined, and an optimal policy is developed. Numerical tests are conducted to verify the analysis and to illustrate the optimal solution algorithm.

Jezewski, D. J.; Donaldson, J. D.

1979-01-01

202

Mission Design for a Multiple-Rendezvous Mission to Jupiter's Trojans  

Microsoft Academic Search

In this paper, we will provide a feasible mission design for a multiple-rendezvous mission to Jupiter's Trojans. It is based on solar electric propulsion, as being currently used on the DAWN spacecraft, and other flight-proven technology. First, we have selected a set of mission objectives, the prime objective being the detection of water -especially subsurface water -to provide evidence for

Volker Maiwald; Bernd Dachwald

2010-01-01

203

Methodology for Prototyping Increased Levels of Automation for Spacecraft Rendezvous Functions  

NASA Technical Reports Server (NTRS)

The Crew Exploration Vehicle necessitates higher levels of automation than previous NASA vehicles, due to program requirements for automation, including Automated Rendezvous and Docking. Studies of spacecraft development often point to the locus of decision-making authority between humans and computers (i.e. automation) as a prime driver for cost, safety, and mission success. Therefore, a critical component in the Crew Exploration Vehicle development is the determination of the correct level of automation. To identify the appropriate levels of automation and autonomy to design into a human space flight vehicle, NASA has created the Function-specific Level of Autonomy and Automation Tool. This paper develops a methodology for prototyping increased levels of automation for spacecraft rendezvous functions. This methodology is used to evaluate the accuracy of the Function-specific Level of Autonomy and Automation Tool specified levels of automation, via prototyping. Spacecraft rendezvous planning tasks are selected and then prototyped in Matlab using Fuzzy Logic techniques and existing Space Shuttle rendezvous trajectory algorithms.

Hart, Jeremy J.; Valasek, John

2007-01-01

204

Autonomous satellite rendezvous and docking using lidar and model based vision  

Microsoft Academic Search

Servicing satellites on-orbit requires ability to rendezvous and dock by an unmanned spacecraft with no or minimum human input. Novel imaging sensors and computer vision technologies are required to detect a target spacecraft at a distance of several kilometers and to guide the approaching spacecraft to contact. Current optical systems operate at much shorter distances, provide only bearing and range

Piotr Jasiobedzki; Stephen Se; Tong Pan; Manickam Umasuthan; Michael Greenspan

2005-01-01

205

The Direction of Synthetic Actors in the Film RendezVous a Montreal  

Microsoft Academic Search

This article describes how the synthetic actors Marilyn Monroe and Humphrey Bogart were directed in the film Rendez-vous a Montreal, using the Human Factory software. Innovative points are emphasized. The recreation of famous persons and reconstitution of their personalities, as well as the corresponding animation, are considered from an artistic point of view. Technical points discussed are personalized expressions, abstract

N. Magnenat-Thalmann; Daniel Thalmann

1987-01-01

206

Usage of pre-flight data in short rendezvous mission of Soyuz-TMA spacecrafts  

NASA Astrophysics Data System (ADS)

The paper describes the reduction of the vehicle autonomous flight duration before docking to the ISS. The Russian Soyuz-TMA spacecraft dock to the ISS two days after launch. Due to the limited volume inside Soyuz-TMA the reduction of time until docking to the ISS is very important, since the long stay of the cosmonauts in the limited volume adds to the strain of the space flight. In the previous papers of the authors it was shown that the existing capabilities of Soyuz-TMA, the ISS and the ground control loop make it possible to transfer to the five-orbit rendezvous profile. However, the analysis of the cosmonauts' schedule on the launch day shows that its duration is at the allowable limit and that is why it is necessary to find a way to further reduce the flight duration of Soyuz-TMA before docking to less than five orbits. In a traditional rendezvous profile, the calculation of rendezvous burns begins only after determination of the actual vehicle insertion orbit. The paper describes an approach in which the first two rendezvous burns are performed as soon as the spacecraft reaches the reference orbit and the values of the burns are calculated prior to the launch based on the pre-flight data for the nominal insertion. This approach decreases the duration of the rendezvous by one orbit. The demonstration flight of a Progress vehicle using the proposed profile was implemented on August 1, 2012 and completely confirmed the correctness of the imbedded principles. The paper considers the possible improvements of the proposed approach and recovery from the contingencies.

Murtazin, Rafail; Petrov, Nikolay

2014-01-01

207

Coupling fast water exchange to slow molecular tumbling in Gd3+ chelates: why faster is not always better  

PubMed Central

The influence of dynamics on solution state structure is a widely overlooked consideration in chemistry. Variations in Gd3+ chelate hydration with changing coordination geometry and dissociative water exchange kinetics substantially impact the effectiveness (or relaxivity) of mono-hydrated Gd3+ chelates as T1-shortening contrast agents for MRI. Theory shows that relaxivity is highly dependent upon the Gd3+-water proton distance (rGdH) and yet this distance is almost never considered as a variable in assessing the relaxivity of a Gd3+ chelate as a potential contrast agent. The consequence of this omission can be seen when considering the relaxivity of isomeric Gd3+ chelates that exhibit different dissociative water exchange kinetics. The results described herein show that the relaxivity of a chelate with ‘optimal’ dissociative water exchange kinetics is actually lower than that of an isomeric chelate with ‘sub-optimal’ dissociative water exchange. When the rate of molecular tumbling of these chelates is slowed, an approach that has long been understood to increase relaxivity, the observed difference in relaxivity is increased with the more rapidly exchanging (‘optimal’) chelate exhibiting lower relaxivity than the ‘sub-optimally’ exchanging isomer. The difference between the chelates arises from a non-field dependent parameter: either the hydration number (q) or rGdH. For solution state Gd3+ chelates, changes in the values of q and rGdH are indistinguishable. These parametric expressions simply describe the hydration state of the chelate – i.e. the number and position of closely associating water molecules. The hydration state (q/rGdH6) of a chelate is intrinsically linked to its dissociative water exchange rate kex and the interrelation of these parameters must be considered when examining the relaxivity of Gd3+ chelates. The data presented herein indicates that the changes in the hydration parameter (q/rGdH6) associated with changing dissociative water exchange kinetics has a profound effect on relaxivity and suggest that achieving the highest relaxivities in monohydrated Gd3+ chelates is more complicated than simply “optimizing” dissociative water exchange kinetics. PMID:23841587

Avedano, Stefano; Botta, Mauro; Haigh, Julian S.; Longo, Dario; Woods, Mark

2013-01-01

208

Fuel optimal low thrust rendezvous with outer planets via gravity assist  

NASA Astrophysics Data System (ADS)

Low thrust propulsion and gravity assist (GA) are among the most promising techniques for deep space explorations. In this paper the two techniques are combined and treated comprehensively, both on modeling and numerical techniques. Fuel optimal orbit rendezvous via multiple GA is first formulated as optimal guidance with multiple interior constraints and then the optimal necessary conditions, various transversality conditions and stationary conditions are derived by Pontryagin's Maximum Principle (PMP). Finally the initial orbit rendezvous problem is transformed into a multiple point boundary value problem (MPBVP). Homotopic technique combined with random searching globally and Particle Swarm Optimization (PSO), is adopted to handle the numerical difficulty in solving the above MPBVP by single shooting method. Two scenarios in the end show the merits of the present approach.

Guo, TieDing; Jiang, FangHua; Baoyin, HeXi; LI, JunFeng

2011-04-01

209

Relative position and attitude estimation of spacecrafts based on dual quaternion for rendezvous and docking  

NASA Astrophysics Data System (ADS)

The capacity to acquire the relative position and attitude information between the chaser and the target satellites in real time is one of the necessary prerequisites for the successful implementation of autonomous rendezvous and docking. This paper addresses a vision based relative position and attitude estimation algorithm for the final phase of spacecraft rendezvous and docking. By assuming that the images of feature points on the target satellite lie within the convex regions, the estimation of the relative position and attitude is converted into solving a convex optimization problem in which the dual quaternion method is employed to represent the rotational and translational transformation between the chaser body frame and the target body frame. Due to the point-to-region correspondence instead of the point-to-point correspondence is used, the proposed estimation algorithm shows good performance in robustness which is verified through computer simulations.

Qiao, Bing; Tang, Shuren; Ma, Kexin; Liu, Zhenya

2013-10-01

210

Model predictive control application to spacecraft rendezvous in mars sample return scenario  

NASA Astrophysics Data System (ADS)

Model Predictive Control (MPC) is an optimization-based control strategy that is considered extremely attractive in the autonomous space rendezvous scenarios. The Online Recon¦guration Control System and Avionics Architecture (ORCSAT) study addresses its applicability in Mars Sample Return (MSR) mission, including the implementation of the developed solution in a space representative avionic architecture system. With respect to a classical control solution High-integrity Autonomous RendezVous and Docking control system (HARVD), MPC allows a signi¦cant performance improvement both in trajectory and in propellant save. Furthermore, thanks to the online optimization, it allows to identify improvements in other areas (i. e., at mission de¦nition level) that could not be known a priori.

Saponara, M.; Barrena, V.; Bemporad, A.; Hartley, E. N.; Maciejowski, J.; Richards, A.; Tramutola, A.; Trodden, P.

2013-12-01

211

Low-Cost Innovation in Spaceflight: The Near Earth Asteroid Rendezvous (NEAR) Shoemaker Mission  

NASA Technical Reports Server (NTRS)

On a spring day in 1996, at their research center in the Maryland countryside, representatives from the Johns Hopkins University Applied Physics Laboratory (APL) presented Administrator Daniel S. Goldin of the National Aeronautics and Space Administration (NASA) with a check for $3.6 million. 1 Two and a half years earlier, APL officials had agreed to develop a spacecraft capable of conducting an asteroid rendezvous and to do so for slightly more than $122 million. This was a remarkably low sum for a spacecraft due to conduct a planetaryclass mission. By contrast, the Mars Observer spacecraft launched in 1992 for an orbital rendezvous with the red planet had cost $479 million to develop, while the upcoming Cassini mission to Saturn required a spacecraft whose total cost was approaching $1.4 billion. In an Agency accustomed to cost overruns on major missions, the promise to build a planetary-class spacecraft for about $100 million seemed excessively optimistic.

McCurdy, Howard E.

2005-01-01

212

Investigation of a Lagrangian-point propellant depot rendezvous approach for an interplanetary mission to Mars  

NASA Astrophysics Data System (ADS)

This thesis investigates the feasibility of a refueling station for a beyond Earth orbit (BEO) mission. The propellant depot is located at the L2-Lagrangian point within the Earth-Moon system. This investigation determines if a refueling mission will reduce propulsive energy requirements necessary for Earth departure of a BEO-vehicle to achieve an interplanetary transfer to Mars. Furthermore, this research presents a trade study which identifies approximate total requirements for a direct and rendezvous mission to Mars as well as the necessary fuel masses to complete each approach. This analysis provides conclusive information in determining the benefits in utilizing a rendezvous location for refueling a spacecraft en versus loading the required fuel masses into a launch vehicle to support a direct transfer to Mars.

Ehrlich, Joshua W.

213

Mission options for the first SEPS application. [rendezvous with near earth asteroids and comets  

NASA Technical Reports Server (NTRS)

Missions to comets and asteroids are primary candidates for Solar Electric Propulsion System (SEPS) applications. NASA estimates that the first SEPS mission might be launched as early as 1988. This paper presents mission opportunities available for launches between 1988 and early 1991 and discusses the performance capabilities of the current SEPS. Use of a Shuttle Two-Stage IUS and/or a Shuttle Wide Tank Centaur launch vehicle is assumed in the performance assessment. The list of possible first SEPS missions consists of nine missions to comets of primary interest and examples of multiple asteroid rendezvous missions. Both an earth crossing asteroid and a main belt asteroid are considered as first possible targets in the multiple asteroid rendezvous examples. Mission opportunity and performance maps for Eros and Anteros are presented which provide exact performance data and optimal launch and arrival dates for any launch year.

Yen, C.-W. L.

1981-01-01

214

Rendezvous-guidance trajectory planning for robotic dynamic obstacle avoidance and interception.  

PubMed

This correspondence presents a novel online trajectory-planning method for the autonomous robotic interception of moving targets in the presence of dynamic obstacles, i.e., position and velocity matching (also referred to as rendezvous). The proposed time-optimal interception method is a hybrid algorithm that augments a novel rendezvous-guidance (RG) technique with the velocity-obstacle approach, for obstacle avoidance, first reported by Fiorini and Shiller. The obstacle-avoidance algorithm itself could not be used in its original form and had to be modified to ensure that the online planned path deviates minimally from the one generated by the RG algorithm. Extensive simulation and experimental analyses, some of which are reported in this correspondence, have clearly demonstrated the tangible time efficiency of the proposed interception method. PMID:17186819

Kunwar, Faraz; Benhabib, Beno

2006-12-01

215

Optimal impulsive time-fixed orbital rendezvous and interception with path constraints  

NASA Technical Reports Server (NTRS)

Minimum-fuel, impulsive, time-fixed solutions are obtained for the problem of orbital rendezvous and interception with interior path constraints. Transfers between coplanar circular orbits in an inverse-square gravitational field are considered, subject to a circular path constraint representing a minimum or maximum permissible orbital radius. Primer vector theory is extended to incorporate path constraints. The optimal number of impulses, their times and positions, and the presence of initial or final coasting arcs are determined. The existence of constraint boundary arcs and boundary points is investigated as well as the optimality of a class of singular arc solutions. To illustrate the complexities introduced by path constraints, an analysis is made of optimal rendezvous in field-free space subject to a minimum radius constraint.

Taur, D.-R.; Prussing, J. E.; Coverstone-Carroll, V.

1990-01-01

216

Analytical Evaluation of a Method of Midcourse Guidance for Rendezvous with Earth Satellites  

NASA Technical Reports Server (NTRS)

A digital-computer simulation was made of the midcourse or ascent phase of a rendezvous between a ferry vehicle and a space station. The simulation involved a closed-loop guidance system in which both the relative position and relative velocity between ferry and station are measured (by simulated radar) and the relative-velocity corrections required to null the miss distance are computed and applied. The results are used to study the effectiveness of a particular set of guidance equations and to study the effects of errors in the launch conditions and errors in the navigation data. A number of trajectories were investigated over a variety of initial conditions for cases in which the space station was in a circular orbit and also in an elliptic orbit. Trajectories are described in terms of a rotating coordinate system fixed in the station. As a result of this study the following conclusions are drawn. Successful rendezvous can be achieved even with launch conditions which are substantially less accurate than those obtained with present-day techniques. The average total-velocity correction required during the midcourse phase is directly proportional to the radar accuracy but the miss distance is not. Errors in the time of booster burnout or in the position of the ferry at booster burnout are less important than errors in the ferry velocity at booster burnout. The use of dead bands to account for errors in the navigational (radar) equipment appears to depend upon a compromise between the magnitude of the velocity corrections to be made and the allowable miss distance at the termination of the midcourse phase of the rendezvous. When approximate guidance equations are used, there are limits on their accuracy which are dependent on the angular distance about the earth to the expected point of rendezvous.

Eggleston, John M.; Dunning, Robert S.

1961-01-01

217

Automated rendezvous and docking sensor testing at the flight robotics laboratory  

NASA Astrophysics Data System (ADS)

The Exploration Systems Architecture defines missions that require rendezvous, proximity operations, and docking (RPOD) of two spacecraft both in Low Earth Orbit (LEO) and in Low Lunar Orbit (LLO). Uncrewed spacecraft must perform automated and/or autonomous rendezvous, proximity operations and docking operations (commonly known as Automated Rendezvous and Docking, (AR&D).) The crewed versions of the spacecraft may also perform AR&D, possibly with a different level of automation and/or autonomy, and must also provide the crew with relative navigation information for manual piloting. The capabilities of the RPOD sensors are critical to the success of the Exploration Program. NASA has the responsibility to determine whether the Crew Exploration Vehicle (CEV) contractor-proposed relative navigation sensor suite will meet the CEV requirements. The relatively low technology readiness of relative navigation sensors for AR&D has been carried as one of the CEV Projects top risks. The AR&D Sensor Technology Project seeks to reduce this risk by increasing technology maturation of selected relative navigation sensor technologies through testing and simulation, and to allow the CEV Project to assess the relative navigation sensors.

Howard, Richard T.; Williamson, Marlin L.; Johnston, Albert S.; Brewster, Linda L.; Mitchell, Jennifer D.; Cryan, Scott P.; Strack, David; Key, Kevin

2007-04-01

218

Rapid design and optimization of low-thrust rendezvous/interception trajectory for asteroid deflection missions  

NASA Astrophysics Data System (ADS)

Asteroid deflection techniques are essential in order to protect the Earth from catastrophic impacts by hazardous asteroids. Rapid design and optimization of low-thrust rendezvous/interception trajectories is considered as one of the key technologies to successfully deflect potentially hazardous asteroids. In this paper, we address a general framework for the rapid design and optimization of low-thrust rendezvous/interception trajectories for future asteroid deflection missions. The design and optimization process includes three closely associated steps. Firstly, shape-based approaches and genetic algorithm (GA) are adopted to perform preliminary design, which provides a reasonable initial guess for subsequent accurate optimization. Secondly, Radau pseudospectral method is utilized to transcribe the low-thrust trajectory optimization problem into a discrete nonlinear programming (NLP) problem. Finally, sequential quadratic programming (SQP) is used to efficiently solve the nonlinear programming problem and obtain the optimal low-thrust rendezvous/interception trajectories. The rapid design and optimization algorithms developed in this paper are validated by three simulation cases with different performance indexes and boundary constraints.

Li, Shuang; Zhu, Yongsheng; Wang, Yukai

2014-02-01

219

Precision spacecraft rendezvous using global positioning system: An integrated hardware approach  

NASA Astrophysics Data System (ADS)

The objective of this dissertation is to develop a precision rendezvous methodology for Earth orbiting spacecraft utilizing the Global Positioning System (GPS). A GPS receiver is placed on each space vehicle and a communication link is used to pass GPS measurements from the target to the chaser spacecraft. The integrated navigation and guidance system resides on the chaser vehicle. The fundamental component of the measurement processing navigation system is a real-time recursive extended Kalman filter (EKF). The navigation system provides absolute and relative position and velocity estimates that are used by the on-board guidance for computing rendezvous maneuvers without ground support. To achieve very precise relative navigation, the filter processes double-difference carrier phase measurements. The unavoidable double-difference integer ambiguity is part of the filter state and is treated as a real number. The Global Simulation Systems (GSS) STR4760 GPS signal generator was used to perform open-loop simulations to evaluate the relative navigation filter performance in conjunction with a commercial, user programmable GPS receiver that was extensively modified for space applications. Open-loop implies that no on-board targeted rendezvous maneuvers are executed. The open-loop simulation investigations show that a 5 cm or less relative positioning accuracy and about a 1 mm/s relative velocity estimation accuracy are achievable. With these highly accurate relative navigation results, the notion of autonomous space rendezvous becomes plausible. One of the key contributions of this research involves the development of a hardware-in-the loop (HWIL) GPS test facility, which is capable of performing active closed-loop scenarios in real-time mode with actual GPS signal processing hardware. The GSS STR4760 is a closed-loop simulation system capable with the GSS STR4762 Remote Control option. The HWIL GPS test facility was constructed and configured to evaluate the newly developed relative navigation algorithms integrated with on-board targeting from real-time navigation data. This is the first time this type of hardware for closed-loop spacecraft rendezvous experiments has been reported.

Ebinuma, Takuji

220

Diffusion, sedimentation equilibrium, and harmonic trapping of run-and-tumble nanoswimmers.  

PubMed

The diffusion of self-propelling nanoswimmers is explored by dissipative particle dynamics in which a nanoswimmer swims by forming an instantaneous force dipole with one of its nearest neighboring solvent beads. Our simulations mimic run-and-tumble behavior by letting the swimmer run for a time ?, then it randomly changes its direction for the next run period. Our simulations show that the swimming speed (?(a)) of a nanoswimmer is proportional to the propulsion force and the mobility of a pusher is the same as that of a puller. The effective diffusivity is determined by three methods: mean squared displacement, velocity autocorrelation function, and sedimentation equilibrium. The active colloid undergoes directed propulsion at short time scales but changes to random motion at long time scales. The velocity autocorrelation function decreases with time and becomes zero beyond the run time. Under gravity, the concentration profile of active colloids follows Boltzmann distribution with a sedimentation length consistent with that acquired from the drift-diffusion equation. In our simulation, all three methods yield the same result, the effective diffusivity of an active colloid is the sum of the diffusivity of a passive colloid and ?(a)˛?/6. When the active colloids are confined by a harmonic well, they are trapped within a confinement length defined by the balance between the swimmer active force and restoring force of the well. When the confinement length is large compared to the run length, the stationary density profile follows the Boltzmann distribution. However, when the run length exceeds the confinement length, the density distribution is no longer described by Boltzmann distribution, instead we found a bimodal distribution. PMID:24718999

Wang, Zhengjia; Chen, Hsuan-Yi; Sheng, Yu-Jane; Tsao, Heng-Kwong

2014-05-14

221

SPARTAN: A High-Fidelity Simulation for Automated Rendezvous and Docking Applications  

NASA Technical Reports Server (NTRS)

bd Systems (a subsidiary of SAIC) has developed the Simulation Package for Autonomous Rendezvous Test and ANalysis (SPARTAN), a high-fidelity on-orbit simulation featuring multiple six-degree-of-freedom (6DOF) vehicles. SPARTAN has been developed in a modular fashion in Matlab/Simulink to test next-generation automated rendezvous and docking guidance, navigation,and control algorithms for NASA's new Vision for Space Exploration. SPARTAN includes autonomous state-based mission manager algorithms responsible for sequencing the vehicle through various flight phases based on on-board sensor inputs and closed-loop guidance algorithms, including Lambert transfers, Clohessy-Wiltshire maneuvers, and glideslope approaches The guidance commands are implemented using an integrated translation and attitude control system to provide 6DOF control of each vehicle in the simulation. SPARTAN also includes high-fidelity representations of a variety of absolute and relative navigation sensors that maybe used for NASA missions, including radio frequency, lidar, and video-based rendezvous sensors. Proprietary navigation sensor fusion algorithms have been developed that allow the integration of these sensor measurements through an extended Kalman filter framework to create a single optimal estimate of the relative state of the vehicles. SPARTAN provides capability for Monte Carlo dispersion analysis, allowing for rigorous evaluation of the performance of the complete proposed AR&D system, including software, sensors, and mechanisms. SPARTAN also supports hardware-in-the-loop testing through conversion of the algorithms to C code using Real-Time Workshop in order to be hosted in a mission computer engineering development unit running an embedded real-time operating system. SPARTAN also contains both runtime TCP/IP socket interface and post-processing compatibility with bdStudio, a visualization tool developed by bd Systems, allowing for intuitive evaluation of simulation results. A description of the SPARTAN architecture and capabilities is provided, along with details on the models and algorithms utilized and results from representative missions.

Turbe, Michael A.; McDuffie, James H.; DeKock, Brandon K.; Betts, Kevin M.; Carrington, Connie K.

2007-01-01

222

Constant-thrust glideslope guidance algorithm for time-fixed rendezvous in real halo orbit  

NASA Astrophysics Data System (ADS)

This paper presents a fixed-time glideslope guidance algorithm that is capable of guiding the spacecraft approaching a target vehicle on a quasi-periodic halo orbit in real Earth-Moon system. To guarantee the flight time is fixed, a novel strategy for designing the parameters of the algorithm is given. Based on the numerical solution of the linearized relative dynamics of the Restricted Three-Body Problem (expressed in inertial coordinates with a time-variant nature), the proposed algorithm breaks down the whole rendezvous trajectory into several arcs. For each arc, a two-impulse transfer is employed to obtain the velocity increment (delta-v) at the joint between arcs. Here we respect the fact that instantaneous delta-v cannot be implemented by any real engine, since the thrust magnitude is always finite. To diminish its effect on the control, a thrust duration as well as a thrust direction are translated from the delta-v in the context of a constant thrust engine (the most robust type in real applications). Furthermore, the ignition and cutoff delays of the thruster are considered as well. With this high-fidelity thrust model, the relative state is then propagated to the next arc by numerical integration using a complete Solar System model. In the end, final corrective control is applied to insure the rendezvous velocity accuracy. To fully validate the proposed guidance algorithm, Monte Carlo simulation is done by incorporating the navigational error and the thrust direction error. Results show that our algorithm can effectively maintain control over the time-fixed rendezvous transfer, with satisfactory final position and velocity accuracies for the near-range guided phase.

Lian, Yijun; Meng, Yunhe; Tang, Guojian; Liu, Luhua

2012-10-01

223

Third Report of the Task Force on the Shuttle-Mir Rendezvous and Docking Missions  

NASA Technical Reports Server (NTRS)

In May 1994, the Task Force on the Shuttle-Mir Rendezvous and Docking Missions was established by the NASA Advisory Council. Its purpose is to review Phase 1 (Shuttle-Mir) planning, training, operations, rendezvous and docking, and management and to provide interim reports containing specific recommendations to the Advisory Council. Phase 1 represents the building block to create the experience and technical expertise for an International Space Station. The Phase 1 program brings together the United States and Russia in a major cooperative and contractual program that takes advantage of both countries' capabilities. The content of the Phase 1 program consists of the following elements as defined by the Phase 1 Program Management Plan, dated October 6, 1994: Shuttle-Mir rendezvous and docking missions; astronaut long duration presence on Mir Requirements for Mir support of Phase 1 when astronauts are not on board; outfitting Spektr and Priroda modules with NASA science, research, and risk mitigation equipment Related ground support requirements of NASA and the Russian Space Agency (RSA) to support Phase 1 Integrated NASA and RSA launch schedules and manifests The first meeting of the Task Force was held at the Johnson Space Center (JSC) on May 24 and 25, 1994 with a preliminary report submitted to the NASA Advisory Council on June 6, 1994. The second meeting of the Task Force was held at JSC on July 12 and 13, 1994 and a detailed report containing a series of specific recommendations was submitted on July 29, 1994. This report reflects the results of the third Task Force meeting which was held at JSC on 11 and 12 October, 1994. The briefings presented at that meeting reviewed NASA's response to the Task Force recommendations made to date and provided background data and current status on several critical areas which the Task Force had not addressed in its previous reports.

1994-01-01

224

Effect of field size, head motion, and rotational velocity on roll vection and illusory self-tilt in a tumbling room  

NASA Technical Reports Server (NTRS)

The effect of field size, velocity, and visual fixation upon the perception of self-body rotation and tilt was examined in a rotating furnished room. Subjects sat in a stationary chair in the furnished room which could be rotated about the body roll axis. For full-field conditions, complete 360 degrees body rotation (tumbling) was the most common sensation (felt by 80% of subjects). Constant tilt or partial tumbling (less than 360 degrees rotation) occurred more frequently with a small field of view (20 deg). The number of subjects who experienced complete tumbling increased with increases in field of view and room velocity (for velocities between 15 and 30 degrees s-1). The speed of perceived self-rotation relative to room rotation also increased with increasing field of view.

Allison, R. S.; Howard, I. P.; Zacher, J. E.; Oman, C. M. (Principal Investigator)

1999-01-01

225

Embedded Relative Navigation Sensor Fusion Algorithms for Autonomous Rendezvous and Docking Missions  

NASA Technical Reports Server (NTRS)

bd Systems (a subsidiary of SAIC) has developed a suite of embedded relative navigation sensor fusion algorithms to enable NASA autonomous rendezvous and docking (AR&D) missions. Translational and rotational Extended Kalman Filters (EKFs) were developed for integrating measurements based on the vehicles' orbital mechanics and high-fidelity sensor error models and provide a solution with increased accuracy and robustness relative to any single relative navigation sensor. The filters were tested tinough stand-alone covariance analysis, closed-loop testing with a high-fidelity multi-body orbital simulation, and hardware-in-the-loop (HWIL) testing in the Marshall Space Flight Center (MSFC) Flight Robotics Laboratory (FRL).

DeKock, Brandon K.; Betts, Kevin M.; McDuffie, James H.; Dreas, Christine B.

2008-01-01

226

Manned Mars lander launch-to-rendezvous analysis for a 1981 Venus-swingby mission  

NASA Technical Reports Server (NTRS)

A description is given of the return of a manned Mars lander by a launch from the surface of Mars to some intermediate orbit, with subsequent maneuvers to rendezvous with a primary spacecraft (called the orbiter) in a Mars parking orbit. The type of Mars mission used to demonstrate the analytical technique includes a Venus swingby on the Mars-to-Earth portion of the trajectory in order to reduce the total mission velocity requirement. The total velocity requirement for the mission considered (if inplane launches are assumed) is approximately 17,500 ft/sec.

Faust, N. L.; Murtagh, T. B.

1971-01-01

227

Rendezvous technique following thermal ureteric injury after radiofrequency ablation in a solitary kidney.  

PubMed

Percutaneous radiofrequency (RF) ablation is a promising treatment for solid renal tumors in selected patients. Nontarget thermal damage is a known risk of the procedure. The authors describe a case of a patient who underwent RF ablation of a lower pole renal lesion and subsequently developed a ureteric stricture secondary to thermal injury. Successful management of the ureteric stricture required a rendezvous procedure. This report illustrates the potential complication of ureteric stricture formation after a RF ablation procedure and the management challenges posed by such thermal injuries. PMID:18589329

Doody, Orla; Given, Mark F; Harper, Matthew; Kavnoudias, Helen; Thomson, Kenneth R; Lyon, Stuart M

2008-07-01

228

Orbit Modification of Earth-Crossing Asteroids/Comets Using Rendezvous Spacecraft and Laser Ablation  

NASA Technical Reports Server (NTRS)

This report describes the approach and results of an end-to-end simulation to deflect a long-period comet (LPC) by using a rapid rendezvous spacecraft and laser ablation system. The laser energy required for providing sufficient deflection DELTA V and an analysis of possible intercept/rendezvous spacecraft trajectories are studied in this analysis. These problems minimize a weighted sum of the flight time and required propellant by using an advanced propulsion system. The optimal thrust-vector history and propellant mass to use are found in order to transfer a spacecraft from the Earth to a targeted celestial object. One goal of this analysis is to formulate an optimization problem for intercept/rendezvous spacecraft trajectories. One approach to alter the trajectory of the object in a highly controlled manner is to use pulsed laser ablative propulsion. A sufficiently intense laser pulse ablates the surface of a near-Earth object (NEO) by causing plasma blowoff. The momentum change from a single laser pulse is very small. However, the cumulative effect is very effective because the laser can interact with the object over long periods of time. The laser ablation technique can overcome the mass penalties associated with other nondisruptive approaches because no propellant is required to generate the DELTA V (the material of the celestial object is the propellant source). Additionally, laser ablation is effective against a wide range of surface materials and does not require any landing or physical attachment to the object. For diverting distant asteroids and comets, the power and optical requirements of a laser ablation system on or near the Earth may be too extreme to contemplate in the next few decades. A hybrid solution would be for a spacecraft to carry a laser as a payload to a particular celestial body. The spacecraft would require an advanced propulsion system capable of rapid rendezvous with the object and an extremely powerful electrical generator, which is likely needed for the propulsion system as well. The spacecraft would station-keep with the object at a small standoff distance while the laser ablation is performed.

Park, Sang-Young; Mazanek, Daniel D.

2005-01-01

229

NASA Automated Rendezvous and Capture Review. A compilation of the abstracts  

NASA Technical Reports Server (NTRS)

This document presents a compilation of abstracts of papers solicited for presentation at the NASA Automated Rendezvous and Capture Review held in Williamsburg, VA on November 19-21, 1991. Due to limitations on time and other considerations, not all abstracts could be presented during the review. The organizing committee determined however, that all abstracts merited availability to all participants and represented data and information reflecting state-of-the-art of this technology which should be captured in one document for future use and reference. The organizing committee appreciates the interest shown in the review and the response by the authors in submitting these abstracts.

1991-01-01

230

Saturn ring rendezvous mission utilizing a tethered sub-satellite  

NASA Technical Reports Server (NTRS)

By combining the advanced technologies of constant-thrust propulsion and space tethers in a planetary mission, it may be feasible to perform a complete radial and azimuthal survey of the Saturnian ring system from close range (about 10 km) in a period of some 300 days. Constant-thrust propulsion would provide the means of 'hovering' above the rings while simultaneously spiraling radially inward toward Saturn. Use of a tethered sub-satellite at a distance of 500-1000 km from the main spacecraft would permit an instrumented package to achieve a significant azimuthal angular rate relative to the rings. Exhaustive 360 deg azimuthal mapping at one or two selected distances from Saturn could be performed in a few tens of days.

Bright, Larry E.

1990-01-01

231

Rough-and-Tumble Play and the Development of Physical Aggression and Emotion Regulation: A Five-Year Follow-Up Study  

Microsoft Academic Search

This is a follow-up to a study demonstrating that rough-and-tumble play was related to physical aggression in the preschool\\u000a years. Fathers reported on the frequency of father-child rough-and-tumble play interactions, and the degree to which fathers\\u000a were dominant in the play dyad was observed and coded from play interactions. In this follow-up study, school-aged children’s\\u000a physically aggressive behaviors and emotion

Joseph L. Flanders; Melissa Simard; Daniel Paquette; Sophie Parent; Frank Vitaro; Robert O. Pihl; Jean R. Séguin

2010-01-01

232

Effects of beef enhancement with non-meat ingredients, blade tenderization, and vacuum tumbling on quality attributes of four beef cuts stored in a high oxygen environment  

E-print Network

of Advisory Committee: Dr. Rhonda K. Miller The objective of this study was to evaluate the effects of non-meat ingredients, blade tenderization and vacuum-tumbling on the textural, visual and sensory characteristics of steaks from Biceps femoris....01) in injected steaks for all muscles except in Biceps femoris steaks. Injected steaks had higher pH (P<0.01) measurements than non-injected treatments in all muscles except the Triceps brachii long head. Neither blade tenderization nor vacuum-tumbling had...

Williams, Tracey Ann

2005-02-17

233

Study on Performance of Integration Control by Man and Machine in Stage of Final Approaching for Spaceship Rendezvous and Docking  

NASA Astrophysics Data System (ADS)

With the development of manned space technology, space rendezvous and docking (RVD) technology will play a more and more important role. The astronauts’ participation in a final close period of man-machine combination control is an important way of RVD technology. Spacecraft RVD control involves control problem of a total of 12 degrees of freedom (location) and attitude which it relative to the inertial space the orbit. Therefore, in order to reduce the astronauts’ operation load and reduce the security requirements to the ground station and achieve an optimal performance of the whole man-machine system, it is need to study how to design the number of control parameters of astronaut or aircraft automatic control system. In this study, with the laboratory conditions on the ground, a method was put forward to develop an experimental system in which the performance evaluation of spaceship RVD integration control by man and machine could be completed. After the RVD precision requirements were determined, 26 male volunteers aged 20-40 took part in the performance evaluation experiments. The RVD integration control success rates and total thruster ignition time were chosen as evaluation indices. Results show that if less than three RVD parameters control tasks were finished by subject and the rest of parameters control task completed by automation, the RVD success rate would be larger than eighty-eight percent and the fuel consumption would be optimized. In addition, there were two subjects who finished the whole six RVD parameters control tasks by enough train. In conclusion, if the astronauts' role should be integrated into the RVD control, it was suitable for them to finish the heading, pitch and roll control in order to assure the man-machine system high performance. If astronauts were needed to finish all parameter control, two points should be taken into consideration, one was enough fuel and another was enough long operation time.

Zhou, Qianxiang; Liu, Zhongqi

234

Pancreatic duct drainage using EUS-guided rendezvous technique for stenotic pancreaticojejunostomy  

PubMed Central

The patient was a 30-year-old female who had undergone excision of the extrahepatic bile duct and Roux-en-Y hepaticojejunostomy for congenital biliary dilatation at the age of 7. Thereafter, she suffered from recurrent acute pancreatitis due to pancreaticobiliary maljunction and received subtotal stomach-preserving pancreaticoduodenectomy. She developed a pancreatic fistula and an intra-abdominal abscess after the operation. These complications were improved by percutaneous abscess drainage and antibiotic therapy. However, upper abdominal discomfort and the elevation of serum pancreatic enzymes persisted due to stenosis from the pancreaticojejunostomy. Because we could not accomplish dilation of the stenosis by endoscopic retrograde cholangiopancreatography, we tried an endoscopic ultrasonography (EUS) guided rendezvous technique for pancreatic duct drainage. After transgastric puncture of the pancreatic duct using an EUS-fine needle aspiration needle, the guidewire was inserted into the pancreatic duct and finally reached to the jejunum through the stenotic anastomosis. We changed the echoendoscope to an oblique-viewing endoscope, then grasped the guidewire and withdrew it through the scope. The stenosis of the pancreaticojejunostomy was dilated up to 4 mm, and a pancreatic stent was put in place. Though the pancreatic stent was removed after three months, the patient remained symptom-free. Pancreatic duct drainage using an EUS-guided rendezvous technique was useful for the treatment of a stenotic pancreaticojejunostomy after pancreaticoduodenectomy. PMID:23964156

Takikawa, Tetsuya; Kanno, Atsushi; Masamune, Atsushi; Hamada, Shin; Nakano, Eriko; Miura, Shin; Ariga, Hiroyuki; Unno, Jun; Kume, Kiyoshi; Kikuta, Kazuhiro; Hirota, Morihisa; Yoshida, Hiroshi; Katayose, Yu; Unno, Michiaki; Shimosegawa, Tooru

2013-01-01

235

Pancreatic duct drainage using EUS-guided rendezvous technique for stenotic pancreaticojejunostomy.  

PubMed

The patient was a 30-year-old female who had undergone excision of the extrahepatic bile duct and Roux-en-Y hepaticojejunostomy for congenital biliary dilatation at the age of 7. Thereafter, she suffered from recurrent acute pancreatitis due to pancreaticobiliary maljunction and received subtotal stomach-preserving pancreaticoduodenectomy. She developed a pancreatic fistula and an intra-abdominal abscess after the operation. These complications were improved by percutaneous abscess drainage and antibiotic therapy. However, upper abdominal discomfort and the elevation of serum pancreatic enzymes persisted due to stenosis from the pancreaticojejunostomy. Because we could not accomplish dilation of the stenosis by endoscopic retrograde cholangiopancreatography, we tried an endoscopic ultrasonography (EUS) guided rendezvous technique for pancreatic duct drainage. After transgastric puncture of the pancreatic duct using an EUS-fine needle aspiration needle, the guidewire was inserted into the pancreatic duct and finally reached to the jejunum through the stenotic anastomosis. We changed the echoendoscope to an oblique-viewing endoscope, then grasped the guidewire and withdrew it through the scope. The stenosis of the pancreaticojejunostomy was dilated up to 4 mm, and a pancreatic stent was put in place. Though the pancreatic stent was removed after three months, the patient remained symptom-free. Pancreatic duct drainage using an EUS-guided rendezvous technique was useful for the treatment of a stenotic pancreaticojejunostomy after pancreaticoduodenectomy. PMID:23964156

Takikawa, Tetsuya; Kanno, Atsushi; Masamune, Atsushi; Hamada, Shin; Nakano, Eriko; Miura, Shin; Ariga, Hiroyuki; Unno, Jun; Kume, Kiyoshi; Kikuta, Kazuhiro; Hirota, Morihisa; Yoshida, Hiroshi; Katayose, Yu; Unno, Michiaki; Shimosegawa, Tooru

2013-08-21

236

Endoscopic Sphincterotomy Using the Rendezvous Technique for Choledocholithiasis during Laparoscopic Cholecystectomy: A Case Report  

PubMed Central

A 50-year-old male was examined at another hospital for fever, general fatigue and slight abdominal pain. He was treated with antibiotics and observed. However, his symptoms did not lessen, and laboratory tests revealed liver dysfunction, jaundice and an increased inflammatory response. He was then admitted to our hospital and underwent an abdominal computed tomography scan and magnetic resonance cholangiopancreatography (MRCP), which revealed common bile duct (CBD) stones. He was diagnosed with mild acute cholangitis. As the same time, he was admitted to our hospital and an emergency endoscopic retrograde cholangiopancreatography was performed. Vater papilla opening in the third portion of the duodenum and presence of a peripapillary duodenal diverticulum made it difficult to perform cannulation of the CBD. In addition, MRCP revealed that the CBD was extremely narrow (diameter 5 mm). We therefore performed laparoscopic cholecystectomy and endoscopic sphincterotomy using the rendezvous technique for choledocholithiasis simultaneously rather than laparoscopic CBD exploration. After the operation, the patient was discharged with no complications. Although the rendezvous technique has not been very commonly used because several experts in the technique and a large operating room are required, this technique is a very attractive and effective approach for treating choledocholithiasis, for which endoscopic treatment is difficult. PMID:25298761

Tanaka, Takayuki; Haraguchi, Masashi; Tokai, Hirotaka; Ito, Shinichiro; Kitajima, Masachika; Ohno, Tsuyoshi; Onizuka, Shinya; Inoue, Keiji; Motoyoshi, Yasuhide; Kuroki, Tamotsu; Kanemastu, Takashi; Eguchi, Susumu

2014-01-01

237

Design and development of guidance navigation and control algorithms for spacecraft rendezvous and docking experimentation  

NASA Astrophysics Data System (ADS)

This paper presents the design of the GNC system of a ground test-bed for spacecraft rendezvous and docking experiments. The test-bed is developed within the STEPS project (Systems and Technologies for Space Exploration). The facility consists of a flat floor and two scaled vehicles, one active chaser and one "semi-active" target. Rendezvous and docking maneuvers are performed floating on the plane with pierced plates as lifting systems. The system is designed to work both with inertial and non-inertial reference frame, receiving signals from navigation sensors as: accelerometers, gyroscopes, laser meter, radio finder and video camera, and combining them with a digital filter. A Proportional-Integrative-Derivative control law and Pulse Width Modulators are used to command the cold gas thrusters of the chaser, and to follow an assigned trajectory with its specified velocity profile. The design and development of the guidance, navigation and control system and its architecture—including the software algorithms—are detailed in the paper, presenting a performance analysis based on a simulated environment. A complete description of the integrated subsystems is also presented.

Guglieri, Giorgio; Maroglio, Franco; Pellegrino, Pasquale; Torre, Liliana

2014-01-01

238

A Comparison of Trajectory Optimization Methods for the Impulsive Minimum Fuel Rendezvous Problem  

NASA Technical Reports Server (NTRS)

In this paper we present, a comparison of trajectory optimization approaches for the minimum fuel rendezvous problem. Both indirect and direct methods are compared for a variety of test cases. The indirect approach is based on primer vector theory. The direct approaches are implemented numerically and include Sequential Quadratic Programming (SQP). Quasi- Newton and Nelder-Meade Simplex. Several cost function parameterizations are considered for the direct approach. We choose one direct approach that appears to be the most flexible. Both the direct and indirect methods are applied to a variety of test cases which are chosen to demonstrate the performance of each method in different flight regimes. The first test case is a simple circular-to-circular coplanar rendezvous. The second test case is an elliptic-to-elliptic line of apsides rotation. The final test case is an orbit phasing maneuver sequence in a highly elliptic orbit. For each test case we present a comparison of the performance of all methods we consider in this paper.

Hughes, Steven P.; Mailhe, Laurie M.; Guzman, Jose J.

2003-01-01

239

A relative navigation application of ULTOR technology for automated rendezvous and docking  

NASA Astrophysics Data System (ADS)

NASA's initiative for space exploration will require the development of robotic servicing and unmanned resupply of permanent space borne facilities. An enabling technology to accomplish these goals is by sensor systems capable of Rendezvous, Proximity Operations and Docking (RPOD) missions. Marshall Space Flight Center (MSFC) conducted an experiment whose objective intent was to characterize sensor systems for potential use in RPOD scenarios. The MSFC experiment integrated candidate sensors with the Small Air Sled (SAS) on the air bearing floor of the MSFC Flight Robotics Lab. Advanced Optical Systems Inc. (AOS) has developed several different sensor technologies for Automated Rendezvous and Docking (AR&D). For the MSFC experiment, we applied AOS ULTOR advanced correlation technology as an AR&D sensor. The ULTOR system applied Automatic Target Recognition (ATR) algorithms to provide six-degrees-of-freedom (6DOF) information for target position and attitude. In addition, ULTOR provided a data-link interface to the SAS for closed loop guidance and navigation commands. Navigational data from the ULTOR system was collected during the experiment and compared to a MSFC truth sensor for position and attitude estimation accuracy. This data will be presented as well as videos recording the progression of the SAS under ULTOR control to the target.

Hannah, S. Joel

2006-05-01

240

An integrated autonomous rendezvous and docking system architecture using Centaur modern avionics  

NASA Astrophysics Data System (ADS)

The avionics system for the Centaur upper stage is in the process of being modernized with the current state-of-the-art in strapdown inertial guidance equipment. This equipment includes an integrated flight control processor with a ring laser gyro based inertial guidance system. This inertial navigation unit (INU) uses two MIL-STD-1750A processors and communicates over the MIL-STD-1553B data bus. Commands are translated into load activation through a Remote Control Unit (RCU) which incorporates the use of solid state relays. Also, a programmable data acquisition system replaces separate multiplexer and signal conditioning units. This modern avionics suite is currently being enhanced through independent research and development programs to provide autonomous rendezvous and docking capability using advanced cruise missile image processing technology and integrated GPS navigational aids. A system concept was developed to combine these technologies in order to achieve a fully autonomous rendezvous, docking, and autoland capability. The current system architecture and the evolution of this architecture using advanced modular avionics concepts being pursued for the National Launch System are discussed.

Nelson, Kurt

241

Space Shuttle Program: Automatic rendezvous, proximity operations, and capture (category 3)  

NASA Technical Reports Server (NTRS)

The NASA Johnson Space Center is actively pursuing the development and demonstration of capabilities for automatic rendezvous, proximity operations, and capture (AR&C) using the Space Shuttle as the active vehicle. This activity combines the technologies, expertise, tools, and facilities of the JSC Tracking and Communications Division (EE), Navigation, Control and Aeronautics Division (EG), Automation and Robotics Division (ER), and Structures and Mechanics Division (ES) of the Engineering Directorate and the Flight Design and Dynamics Division (DM) of the Mission Operations Directorate. Potential benefits of AR&C include more efficient and repeatable rendezvous, proximity operations, and capture operations; reduced impacts on the target vehicles (e.g., Orbiter RCS plume loads); reduced flight crew work loads; reduced ground support requirements; and reduced operational constraints. This paper documents the current JSC capabilities/tools/facilities for AR&C and describes a proposed plan for a progression of ground demonstrations and flight tests and demonstrations of AR&C capabilities. This plan involves the maturing of existing technologies in tracking and communications; guidance, navigation and control; mechanisms; manipulators; and systems management and integrating them into several evolutionary demonstration stages.

Jackson, William L.; Lee, Roscoe; Eick, Richard E.; Hallstrom, J. V.; Hiers, Harry K.; Mcmanamen, John P.; Olszewski, Oscar W.; Prather, Joseph L.; Rue, D. L.; Zimmer, Karl J.

1991-01-01

242

Space Shuttle Guidance, Navigation, and Rendezvous Knowledge Capture Reports. Revision 1  

NASA Technical Reports Server (NTRS)

This document is a catalog and readers guide to lessons learned, experience, and technical history reports, as well as compilation volumes prepared by United Space Alliance personnel for the NASA/Johnson Space Center (JSC) Flight Dynamics Division.1 It is intended to make it easier for future generations of engineers to locate knowledge capture documentation from the Shuttle Program. The first chapter covers observations on documentation quality and research challenges encountered during the Space Shuttle and Orion programs. The second chapter covers the knowledge capture approach used to create many of the reports covered in this document. These chapters are intended to provide future flight programs with insight that could be used to formulate knowledge capture and management strategies. The following chapters contain descriptions of each knowledge capture report. The majority of the reports concern the Space Shuttle. Three are included that were written in support of the Orion Program. Most of the reports were written from the years 2001 to 2011. Lessons learned reports concern primarily the shuttle Global Positioning System (GPS) upgrade and the knowledge capture process. Experience reports on navigation and rendezvous provide examples of how challenges were overcome and how best practices were identified and applied. Some reports are of a more technical history nature covering navigation and rendezvous. They provide an overview of mission activities and the evolution of operations concepts and trajectory design. The lessons learned, experience, and history reports would be considered secondary sources by historians and archivists.

Goodman, John L.

2011-01-01

243

Orbital Express Autonomous Rendezvous and Capture Sensor System (ARCSS) flight test results  

NASA Astrophysics Data System (ADS)

The Orbital Express flight demonstration was established by the Defense Advanced Research Projects Agency (DARPA) to develop and validate key technologies required for cost-effective servicing of next-generation satellites. A contractor team led by Boeing Advanced Network and Space Systems built two mated spacecraft launched atop an Atlas V rocket from Cape Canaveral, Florida, on March 8, 2007. The low earth orbit test flight demonstrated on orbit transfer of hydrazine propellant, transfer of a spare battery between spacecraft and the ability to replace a spacecraft computer on orbit. It also demonstrated autonomous rendezvous and capture (AR&C) using advanced sensor, guidance, and relative navigation hardware and software. This paper summarizes the results of the on-orbit performance testing of the ARCSS (Autonomous Rendezvous and Capture Sensor System). ARCSS uses onboard visible, infrared and laser rangefinder sensors to provide real time data and imagery to the onboard sensor computer. The Boeing-developed Vis-STAR software executing on the sensor computer uses the ARCSS data to provide precision real-time client bearing, range and attitude as needed, from long range to soft capture. The paper summarizes the ARCSS and Vis-STAR on orbit performance.

Leinz, Manny R.; Chen, Chih-Tsai; Beaven, Michael W.; Weismuller, Thomas P.; Caballero, David L.; Gaumer, William B.; Sabasteanski, Peter W.; Scott, Peter A.; Lundgren, Mark A.

2008-04-01

244

Attitude independent estimation of spacecraft angular rate using geomagnetic field observations  

Microsoft Academic Search

*** Abstract- A method is presented for fast estimation of the angular rate of a tumbling spacecraft in a low-Earth orbit, fiom sequential readings of Earth's magnetic field. Useful as a backup algorithm in cases of rate gyro malfunctions, or during the initial acquisition phase, the estimator consists of an extended Kalman filter, based on the underlying assumption that the

P. Tortora; Y. Oshman; F. Santoni

2003-01-01

245

The Successful Development of an Automated Rendezvous and Capture (AR&C) System for the National Aeronautics and Space Administration  

NASA Technical Reports Server (NTRS)

During the 1990's, the Marshall Space Flight Center (MSFC) conducted pioneering research in the development of an automated rendezvous and capture/docking (AR&C) system for U.S. space vehicles. Development and demonstration of a rendezvous sensor was identified early in the AR&C Program as the critical enabling technology that allows automated proximity operations and docking. A first generation rendezvous sensor, the Video Guidance Sensor (VGS), was developed and successfully flown on STS-87 and STS-95, proving the concept of a video- based sensor. A ground demonstration of the entire system and software was successfully tested. Advances in both video and signal processing technologies and the lessons learned from the two successful flight experiments provided a baseline for the development, by the MSFC, of a new generation of video based rendezvous sensor. The Advanced Video Guidance Sensor (AGS) has greatly increased performance and additional capability for longer-range operation with a new target designed as a direct replacement for existing ISS hemispherical reflectors.

Roe, Fred D.; Howard, Richard T.

2003-01-01

246

Aerobraking of a low L\\/D manned vehicle from Geo return to rendezvous with the Space Shuttle  

Microsoft Academic Search

The results of a study of the airbraking portion of the flight of an Apollo class vehicle designed for a sortie from the Orbiter to Geo and return to Leo for Orbiter retrieval are presented. An ablative heat shield would be used on the vehicle to shed velocity to speeds commensurate with Orbiter rendezvous. A reference design was selected for

J. D. Gamble; C. J. Cerimele; K. Spratlin

1983-01-01

247

Usefulness of the 'Rendezvous' Technique in Living Related Right Liver Donors with Postoperative Biliary Leakage from Bile Duct Anastomosis  

SciTech Connect

This is a report on two cases of large bile leak following right hepatectomy performed for living related liver transplantation, originating from the stump of the ligated right bile duct, and treated with the placement of large percutaneous biliary catheters through a combined percutaneous transhepatic and endoscopic approach (rendezvous technique).

Miraglia, R., E-mail: rmiraglia@ismett.ed [Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione (IsMeTT), Department of Radiology (Italy); Traina, M. [Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione (IsMeTT), Department of Endoscopy (Italy); Maruzzelli, L.; Caruso, S. [Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione (IsMeTT), Department of Radiology (Italy); Di Pisa, M. [Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione (IsMeTT), Department of Endoscopy (Italy); Gruttadauria, S. [Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione (IsMeTT), Department of Transplantation Surgery (Italy); Luca, A. [Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione (IsMeTT), Department of Radiology (Italy); Gridelli, B. [Istituto Mediterraneo Trapianti e Terapie ad Alta Specializzazione (IsMeTT), Department of Transplantation Surgery (Italy)

2008-09-15

248

Coordinated Radio, Electron, and Waves Experiment (CREWE) for the NASA Comet Rendezvous and Asteroid Flyby (CRAF) instrument  

Microsoft Academic Search

The Coordinated Radio, Electron, and Waves Experiment (CREWE) was designed to determine density, bulk velocity and temperature of the electrons for the NASA Comet Rendezvous and Asteroid Flyby Spacecraft, to define the MHD-SW IMF flow configuration; to clarify the role of impact ionization processes, to comment on the importance of anomalous ionization phenomena (via wave particle processes), to quantify the

Jack D. Scudder

1992-01-01

249

Androgen and the Development of Human Sex-Typical Behavior: Rough-and-Tumble Play and Sex of Preferred Playmates in Children with Congenital Adrenal Hyperplasia (CAH).  

ERIC Educational Resources Information Center

Examined the rough-and-tumble play and gender of preferred playmates in three- to eight-year olds with congenital adrenal hyperplasia (CAH)--hypothesized to masculinize behaviors that show sex differences--and in unaffected three- to eight-year-old relatives. Found that CAH girls did not exhibit increased levels of masculine behavior when compared…

Hines, Melissa; Kaufman, Francine R.

1994-01-01

250

Wookie Rendezvous  

E-print Network

reminded him to breathe slowly. He reached out and touched the bleeding gash at the boy's temple. It was the only injury immediately noticeable, and Solo probed the ragged wound gently. Whatever had caused it had cut deeply and cleanly; mere... teeth and savagely ripped it into long, ragged strips. Weakly, he paused for breath. He had to stop the bleeding or he would be ofno use to either ofthem. 10 May 1999 And his Corellian senses were screaming to be ac knowledged. He recognized...

Multiple Contributors

1999-01-01

251

Mars Orbit Rendezvous Strategy for the Mars 2003/2005 Sample Return Mission  

NASA Technical Reports Server (NTRS)

The primary objective of the Mars 2003/2005 Sample Return Project is to return Martian surface materials to Earth from two different sites by the year 2008. The baseline mission plan relies heavily on the use of a Mars orbit rendezvous strategy similar to the lunar orbit rendezvous scheme used for the Apollo missions. The 2003 mission consists of a single spacecraft comprised of a Lander, Rover, and Mars ascent vehicle (MAV). The 2003 mission will be launched on a Delta-III-class launch vehicle in May/June 2003 and arrive at Mars in December 2003/January 2004. The Lander deploys the Rover to collect surface samples from several sites and return them to the Lander where they are transferred to a sample canister onboard the MAV. The MAV is launched into a low Mars orbit (targeted for 600 km circular, 45 deg inclination) and releases the sample canister to await retrieval by an Orbiter launched in 2005. (The sample canister is a passive vehicle with no maneuvering capability.) The duration of Mars surface operations is at most about 90 days. The 2005 mission consists of two separate spacecraft: a Lander/Rover/MAV spacecraft identical to that used for the 2003 mission and an Orbiter carrying an Earth Entry Vehicle (EEV). Both spacecraft will be launched on a single Ariane-5 in August 2005 and arrive at Mars in July/August 2006. A second sample canister is delivered to Mars orbit using the same scenario as was used for the 2003 mission. The Orbiter uses aerocapture for insertion into Mars orbit (targeted for 250 x 1400 km, 45 deg inclination). During its approximately one-year stay at Mars, the Orbiter will search for and attempt to rendezvous first with the 2003 sample canister and then with the 2005 sample canister. After retrieval, each sample canister is transferred to the EEV. The Orbiter departs Mars in July 2007 and returns to Earth in October 2008 on a trajectory targeted for landing at the Utah Test and Training Range (UTTR). After deploying the EEV, the Orbiter performs a deflection maneuver to avoid reentry into Earth's atmosphere.

DAmario, Louis A.; Bollman, Willard E.; Lee, Wayne J.; Roncoli, Ralph B.; Smith, John C.

1999-01-01

252

Multi-Sensor Testing for Automated Rendezvous and Docking Sensor Testing at the Flight Robotics Lab  

NASA Technical Reports Server (NTRS)

The Exploration Systems Architecture defines missions that require rendezvous, proximity operations, and docking (RPOD) of two spacecraft both in Low Earth Orbit (LEO) and in Low Lunar Orbit (LLO). Uncrewed spacecraft must perform automated and/or autonomous rendezvous, proximity operations and docking operations (commonly known as AR&D). The crewed missions may also perform rendezvous and docking operations and may require different levels of automation and/or autonomy, and must provide the crew with relative navigation information for manual piloting. The capabilities of the RPOD sensors are critical to the success ofthe Exploration Program. NASA has the responsibility to determine whether the Crew Exploration Vehicle (CEV) contractor-proposed relative navigation sensor suite will meet the requirements. The relatively low technology readiness level of AR&D relative navigation sensors has been carried as one of the CEV Project's top risks. The AR&D Sensor Technology Project seeks to reduce the risk by the testing and analysis of selected relative navigation sensor technologies through hardware-in-the-Ioop testing and simulation. These activities will provide the CEV Project information to assess the relative navigation sensors maturity as well as demonstrate test methods and capabilities. The first year of this project focused on a series of "pathfinder" testing tasks to develop the test plans, test facility requirements, trajectories, math model architecture, simulation platform, and processes that will be used to evaluate the Contractor-proposed sensors. Four candidate sensors were used in the first phase of the testing. The second phase of testing used four sensors simultaneously: two Marshall Space Flight Center (MSFC) Advanced Video Guidance Sensors (AVGS), a laser-based video sensor that uses retroreflectors attached to the target vehicle, and two commercial laser range finders. The multi-sensor testing was conducted at MSFC's Flight Robotics Laboratory (FRL) using the FRL's 6-DOF gantry system, called the Dynamic Overhead Target System (DOTS). The target vehicle for "docking" in the laboratory was a mockup that was representative of the proposed CEV docking system, with added retroreflectors for the AVGS.' The multi-sensor test configuration used 35 open-loop test trajectories covering three major objectives: (l) sensor characterization trajectories designed to test a wide range of performance parameters; (2) CEV-specific trajectories designed to test performance during CEV-like approach and departure profiles; and (3) sensor characterization tests designed for evaluating sensor performance under more extreme conditions as might be induced during a spacecraft failure or during contingency situations. This paper describes the test development, test facility, test preparations, test execution, and test results of the multisensor series oftrajectories

Brewster, Linda L.; Howard, Richard T.; Johnston, A. S.; Carrington, Connie; Mitchell, Jennifer D.; Cryan, Scott P.

2008-01-01

253

Multi-Sensor Testing for Automated Rendezvous and Docking Sensor Testing at the Flight Robotics Laboratory  

NASA Technical Reports Server (NTRS)

The Exploration Systems Architecture defines missions that require rendezvous, proximity operations, and docking (RPOD) of two spacecraft both in Low Earth Orbit (LEO) and in Low Lunar Orbit (LLO). Uncrewed spacecraft must perform automated and/or autonomous rendezvous, proximity operations and docking operations (commonly known as AR&D). The crewed missions may also perform rendezvous and docking operations and may require different levels of automation and/or autonomy, and must provide the crew with relative navigation information for manual piloting. The capabilities of the RPOD sensors are critical to the success of the Exploration Program. NASA has the responsibility to determine whether the Crew Exploration Vehicle (CEV) contractor proposed relative navigation sensor suite will meet the requirements. The relatively low technology readiness level of AR&D relative navigation sensors has been carried as one of the CEV Project's top risks. The AR&D Sensor Technology Project seeks to reduce the risk by the testing and analysis of selected relative navigation sensor technologies through hardware-in-the-loop testing and simulation. These activities will provide the CEV Project information to assess the relative navigation sensors maturity as well as demonstrate test methods and capabilities. The first year of this project focused on a series of"pathfinder" testing tasks to develop the test plans, test facility requirements, trajectories, math model architecture, simulation platform, and processes that will be used to evaluate the Contractor-proposed sensors. Four candidate sensors were used in the first phase of the testing. The second phase of testing used four sensors simultaneously: two Marshall Space Flight Center (MSFC) Advanced Video Guidance Sensors (AVGS), a laser-based video sensor that uses retroreflectors attached to the target vehicle, and two commercial laser range finders. The multi-sensor testing was conducted at MSFC's Flight Robotics Laboratory (FRL) using the FRL's 6-DOF gantry system, called the Dynamic Overhead Target System (DOTS). The target vehicle for "docking" in the laboratory was a mockup that was representative of the proposed CEV docking system, with added retroreflectors for the AVGS. The multi-sensor test configuration used 35 open-loop test trajectories covering three major objectives: (1) sensor characterization trajectories designed to test a wide range of performance parameters; (2) CEV-specific trajectories designed to test performance during CEV-like approach and departure profiles; and (3) sensor characterization tests designed for evaluating sensor performance under more extreme conditions as might be induced during a spacecraft failure or during contingency situations. This paper describes the test development, test facility, test preparations, test execution, and test results of the multi-sensor series of trajectories.

Brewster, L.; Johnston, A.; Howard, R.; Mitchell, J.; Cryan, S.

2007-01-01

254

A Summary of the Rendezvous, Proximity Operations, Docking, and Undocking (RPODU) Lessons Learned from the Defense Advanced Research Project Agency (DARPA) Orbital Express (OE) Demonstration System Mission  

NASA Technical Reports Server (NTRS)

The Guidance, Navigation, and Control (GN&C) Technical Discipline Team (TDT) sponsored Dr. J. Russell Carpenter, a Navigation and Rendezvous Subject Matter Expert (SME) from NASA's Goddard Space Flight Center (GSFC), to provide support to the Defense Advanced Research Project Agency (DARPA) Orbital Express (OE) rendezvous and docking flight test that was conducted in 2007. When that DARPA OE mission was completed, Mr. Neil Dennehy, NASA Technical Fellow for GN&C, requested Dr. Carpenter document his findings (lessons learned) and recommendations for future rendezvous missions resulting from his OE support experience. This report captures lessons specifically from anomalies that occurred during one of OE's unmated operations.

Dennehy, Cornelius J.; Carpenter, James R.

2011-01-01

255

Measurement of radial expansion and tumbling motion of a high-speed rotor using an optical sensor system  

NASA Astrophysics Data System (ADS)

In order to investigate the load capacity and the strength properties of high-speed rotors, dynamic deformation and vibration measurements are of importance, in particular at lightweight composite devices which cannot be simulated reliably. This is a challenging task in metrology since non-contact inspection techniques are required which offer micron uncertainties and high temporal resolution simultaneously, also under vacuum conditions. In order to meet these requirements, a non-incremental laser Doppler distance sensor system was developed using fiber and diffractive optics. In this paper we present for the first time high-speed deformation measurements of a cylindrical steel rotor using this novel sensor system. The radial rotor expansion of only some microns was determined despite the presence of an unsteady tumbling motion of the rotor, which was measured simultaneously. Future prospects are discussed including the possibility to measure non-metallic devices such as fiber-reinforced composites.

Günther, P.; Dreier, F.; Pfister, T.; Czarske, J.; Haupt, T.; Hufenbach, W.

2011-01-01

256

Laparoscopic-endoscopic rendez-vous resection of iuxta-cardial gastric GIST  

PubMed Central

Summary: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and they often require a surgical removal. Gastrointestinal stromal tumors can originate from any part of the gastrointestinal tract but gastric location is the most common. In the past the risk of rupture of pseudocapsula and peritoneal dissemination have discouraged surgeons from making a minimally invasive surgical treatment. Recently laparoscopic wedge resection has been proposed. Performance of this mini-invasive technique is however difficult in some gastric location of gastrointestinal stromal tumors, such as iuxta-cardial region. The Authors report and discuss a new technique they used to remove a gastrointestinal stromal tumor located just below the cardia, using a rendez-vous endoscopic and laparoscopic technique. PMID:23837950

VECCHIO, R.; MARCHESE, S.; AMORE, F.F.; LA CORTE, F.; FERLA, F.; SPATARO, L.; INTAGLIATA, E.

2013-01-01

257

Report of the Task Force on the Shuttle-Mir Rendezvous and Docking Missions  

NASA Technical Reports Server (NTRS)

In October 1992, Russia and the U.S. agreed to conduct a fundamentally new program of human cooperation in space. This original 'Shuttle-Mir' project encompassed combined astronaut-cosmonaut activities on the Shuttle, Soyuz, and Mir spacecraft. At that time, the project was limited to: the STS-60 Shuttle mission, which was completed in February 1994 and carried the first Russian cosmonaut; the planned March 1995 Soyuz 18 launch which will carry a U.S. astronaut to the Mir space station for a three month mission; and the STS-71 Shuttle mission which is scheduled to rendezvous and dock with the Mir space station in June 1995. The Task Force's specific recommendations are given.

1994-01-01

258

Analysis of a Linear System for Variable-Thrust Control in the Terminal Phase of Rendezvous  

NASA Technical Reports Server (NTRS)

A linear system for applying thrust to a ferry vehicle in the 3 terminal phase of rendezvous with a satellite is analyzed. This system requires that the ferry thrust vector per unit mass be variable and equal to a suitable linear combination of the measured position and velocity vectors of the ferry relative to the satellite. The variations of the ferry position, speed, acceleration, and mass ratio are examined for several combinations of the initial conditions and two basic control parameters analogous to the undamped natural frequency and the fraction of critical damping. Upon making a desirable selection of one control parameter and requiring minimum fuel expenditure for given terminal-phase initial conditions, a simplified analysis in one dimension practically fixes the choice of the remaining control parameter. The system can be implemented by an automatic controller or by a pilot.

Hord, Richard A.; Durling, Barbara J.

1961-01-01

259

Autonomous rendezvous and docking: A commercial approach to on-orbit technology validation  

NASA Technical Reports Server (NTRS)

SpARC, in conjunction with its corporate affiliates, is planning an on-orbit validation of autonomous rendezvous and docking (ARD) technology. The emphasis in this program is to utilize existing technology and commercially available components wherever possible. The primary subsystems to be validated by this demonstration include GPS receivers for navigation, a video-based sensor for proximity operations, a fluid connector mechanism to demonstrate fluid resupply capability, and a compliant, single-point docking mechanism. The focus for this initial experiment will be ELV based and will make use of two residual Commercial Experiment Transporter (COMET) service modules. The first COMET spacecraft will be launched in late 1992 and will serve as the target vehicle. After the second COMET spacecraft has been launched in late 1994, the ARD demonstration will take place. The service module from the second COMET will serve as the chase vehicle.

Tchoryk, Peter, Jr.; Whitten, Raymond P.

1991-01-01

260

A family of low-cost transfer orbits for rendezvous-type missions to NEAs  

NASA Astrophysics Data System (ADS)

Low-cost rendezvous missions to near-Earth asteroids (NEAs) are likely to be designed more often in the future, both for scientific exploration and also for impact hazard mitigation. Ballistic orbits are usually highly expensive in terms of energy budget. More sophisticated gravity assisted orbits involve strong phasing requirements between Earth, flyby planets and asteroid. Only few targets are accessible in this manner. In this paper we develop a family of, general purpose, transfer trajectories (called resonant Earth-flyby trajectories) suitable for the peculiarity of NEAs orbits (having at least one orbital node near Earth's orbit). Such a transfer orbit involves one or more deep-space maneuvers (DSMs) and several resonant flyby returns with the Earth. The idea is to build, at first, a large enough relative velocity in respect to the Earth using these DSMs applied near aphelion. Next, successive rotations of this relative velocity vector due to flybys on resonant orbits will, finally, shape the orbit of the spacecraft in order to match the inclination of the asteroid's orbit and, also, the orientation of its apsidal line. Much is done by Earth flybys, without other energy consumptions. On the acquired orbit the spacecraft needs a much smaller velocity impulse to perform the rendezvous. This technique is applicable to most of the NEAs discovered so far, the difference being in phasing requirements and in the total transfer time. The total energy budget will be much smaller compared with the energy budget on free ballistic trajectories. The range of applicability is discussed and near future opportunities are outlined. The theory is developed in the frame of Opik's geometric formalism (two-body orbital transfer), which enable us to track the problem analytically as much as possible.

Berinde, Stefan

2007-05-01

261

Near Earth Asteroid Rendezvous (NEAR) Revised Eros Orbit Phase Trajectory Design  

NASA Technical Reports Server (NTRS)

Trajectory design of the orbit phase of the NEAR mission involves a new process that departs significantly from those procedures used in previous missions. In most cases, a precise spacecraft ephemeris is designed well in advance of arrival at the target body. For NEAR, the uncertainty in the dynamic environment around Eros does not allow the luxury of a precise spacecraft trajectory to be defined in advance. The principal cause of this uncertainty is the limited knowledge oi' the gravity field a,-id rotational state of Eros. As a result, the concept for the NEAR trajectory design is to define a number of rules for satisfying spacecraft, mission, and science constraints, and then apply these rules to various assumptions for the model of Eros. Nominal, high, and low Eros mass models are used for testing the trajectory design strategy and to bracket the ranges of parameter variations that are expected upon arrival at the asteroid. The final design is completed after arrival at Eros and determination of the actual gravity field and rotational state. As a result of the unplanned termination of the deep space rendezvous maneuver on December 20, 1998, the NEAR spacecraft passed within 3830 km of Eros on December 23, 1998. This flyby provided a brief glimpse of Eros, and allowed for a more accurate model of the rotational parameters and gravity field uncertainty. Furthermore, after the termination of the deep space rendezvous burn, contact with the spacecraft was lost and the NEAR spacecraft lost attitude control. During the subsequent gyrations of the spacecraft, hydrazine thruster firings were used to regain attitude control. This unplanned thruster activity used Much of the fuel margin allocated for the orbit phase. Consequently, minimizing fuel consumption is now even more important.

Helfrich, J; Miller, J. K.; Antreasian, P. G.; Carranza, E.; Williams, B. G.; Dunham, D. W.; Farquhar, R. W.; McAdams, J. V.

1999-01-01

262

Two-level optimization approach for Mars orbital long-duration, large non-coplanar rendezvous phasing maneuvers  

NASA Astrophysics Data System (ADS)

A relative dynamics equation-set based on orbital element differences with J2 effects is derived, based on which a two-level approach is proposed to optimize the Mars orbital rendezvous phasing with a large difference in the initial ascending node. The up-level problem uses the revolution deviation between the target spacecraft and the chaser as the design variable, and employs a linear search to find the optimum. The low-level problem uses the maneuver revolutions, locations, and impulses as the design variables, and is solved using a hybrid genetic algorithm combined with sequential quadratic programming. To improve the solution accuracy, an iteration method is developed to satisfy the terminal constraints of the absolute numerical integration trajectory. Test cases involving Mars sample return missions with large initial node differences are presented, which show that the relative dynamics, two-level optimization model, and hybrid optimization algorithm are efficient and robust. Compared with previously published results, the total velocity increment has been further reduced by utilizing this proposed approach. It is found that a five-impulse plan requires the least quantity of propellant, and a propellant-optimal minimum rendezvous duration exists for this long-duration, large non-coplanar rendezvous problem.

Yang, Zhen; Luo, Ya-Zhong; Zhang, Jin

2013-09-01

263

Vacuum to Antimatter-Rocket Interstellar Explorer System (VARIES): A Proposed Program for an Interstellar Rendezvous and Return Architecture  

NASA Astrophysics Data System (ADS)

While interstellar missions have been explored in the literature, one mission architecture has not received much attention, namely the interstellar rendezvous and return mission that could be accomplished on timescales comparable with a working scientist's career. Such a mission would involve an initial boost phase followed by a coasting phase to the target system. Next would be the deceleration and rendezvous phase, which would be followed by a period of scientific data gathering. Finally, there would be a second boost phase, aimed at returning the spacecraft back to the solar system, and subsequent coasting and deceleration phases upon return to our solar system. Such a mission would represent a precursor to a future manned interstellar mission; which in principle could safely return any astronauts back to Earth. In this paper a novel architecture is proposed that would allow for an unmanned interstellar rendezvous and return mission. The approach utilized for the Vacuum to Antimatter-Rocket Interstellar Explorer System (VARIES) would lead to system components and mission approaches that could be utilized for autonomous operation of other deep-space probes. Engineering solutions for such a mission will have a significant impact on future exploration and sample return missions for the outer planets. This paper introduces the general concept, with a mostly qualitative analysis. However, a full research program is introduced, and as this program progresses, more quantitative papers will be released.

Obousy, R.

264

An analytic method of propagating a covariance matrix to a maneuver condition for linear covariance analysis during rendezvous  

NASA Astrophysics Data System (ADS)

This study develops a method for analytically propagating a covariance matrix to a maneuver condition to be used in linear covariance analysis for planning the rendezvous phase of a space mission. With the generalized formulation of a condition transition matrix, an analytic method of propagating an augmented covariance matrix to any scalar terminal maneuver condition is presented. The twenty-six dimensional augmented covariance matrix used in this study includes navigation state errors, state dispersions, and time errors for both the chaser and target craft. The method is first analytically developed. The vehicles are brought to the desired rendezvous condition by linearizing motion at the maneuver condition point and allowing the time of flight to vary slightly. The analytic propagation technique is then validate by comparison to a stochastic Monte Carlo simulation for the case of several elevation angle conditions which might be used to trigger an initial rendezvous intercept burn. The validity of linearizing the motion about the terminal point is substantiated with the same situation.

Gossner, Jesse R.

1991-06-01

265

Rendezvous technique for the treatment of complete common bile duct transection after multiple hepatobiliary surgeries.  

PubMed

Abstract Common bile duct (CBD) injury during surgical procedures is a serious complication. Partial injury can usually be managed by a combination of percutaneous and/or endoscopic techniques. However, the management of complete transection of the CBD is very challenging. There are small case series of nonsurgical management of complete CBD transection during laparoscopic cholecystectomy. In this particular case, a 55-year-old female patient had multiple operations because of malignant pheochromocytoma with liver metastases. She developed a complete CBD transection during right hepatectomy. A biloma was managed with image-guided percutaneous drainage. However, both attempts of percutaneous transhepatic cholangiography (PTC) and endoscopic retrograde cholangiopancreatography (ERCP) for CBD stent were unsuccessful, as the native CBD was partially resected during the injury. A rendezvous procedure, in which a guidewire was placed through the distal CBD and into a biloma by ERCP and subsequently snared with PTC, allowed for a biliary-duodenal catheter to be placed successfully and achieve continuity of the patient's biliary tree. PMID:25180777

Shin, Seung; Klevan, Ariel; Fernandez, Christopher A; Astudillo, J Andres; Martinez, Jose

2014-10-01

266

Fuzzy logic techniques for rendezvous and docking of two geostationary satellites  

NASA Technical Reports Server (NTRS)

Large assemblings in space require the ability to manage rendezvous and docking operations. In future these techniques will be required for the gradual build up of big telecommunication platforms in the geostationary orbit. The paper discusses the use of fuzzy logic to model and implement a control system for the docking/berthing of two satellites in geostationary orbit. The system mounted in a chaser vehicle determines the actual state of both satellites and generates torques to execute maneuvers to establish the structural latching. The paper describes the proximity operations to collocate the two satellites in the same orbital window, the fuzzy guidance and navigation of the chaser approaching the target and the final Fuzzy berthing. The fuzzy logic system represents a knowledge based controller that realizes the close loop operations autonomously replacing the conventional control algorithms. The goal is to produce smooth control actions in the proximity of the target and during the docking to avoid disturbance torques in the final assembly orbit. The knowledge of the fuzzy controller consists of a data base of rules and the definitions of the fuzzy sets. The knowledge of an experienced spacecraft controller is captured into a set of rules forming the Rules Data Base.

Ortega, Guillermo

1995-01-01

267

An overview of autonomous rendezvous and docking system technology development at General Dynamics  

NASA Astrophysics Data System (ADS)

The Centaur avionics suite is undergoing a dramatic modernization for the commercial, DoD Atlas and Titan programs. The system has been upgraded to the current state-of-the-art in ring laser gyro inertial sensors and Mil-Std-1750A processor technology. The Cruise Missile avionic system has similarly been evolving for many years. Integration of GPS into both systems has been underway for over five years with a follow-on cruise missile system currently in flight test. Rendezvous and Docking related studies have been conducted for over five years in support of OMV, CTV, and Advanced Upper Stages, as well as several other internal IR&D's. The avionics system and AR&D simulator demonstrated to the SATWG in November 1990 has been upgraded considerably under two IR&D programs in 1991. The Centaur modern avionics system is being flown in block upgrades which started in July of 1990. The Inertial Navigation Unit will fly in November of 1991. The Cruise Missile avionics systems have been fully tested and operationally validated in combat. The integrated AR&D system for space vehicle applications has been under development and testing since 1990. A Joint NASA / GD ARD&L System Test Program is currently being planned to validate several aspects of system performance in three different NASA test facilities in 1992.

Kuenzel, Fred

268

Fourth Report of the Task Force on the Shuttle-Mir Rendezvous and Docking Missions  

NASA Technical Reports Server (NTRS)

On December 6, 1994, the NASA Administrator, Mr. Daniel Goldin, requested that Lt. Gen. Thomas P. Stafford, in his role as the Chairman of the NASA Advisory Council Task Force on the Shuttle-Mir Rendezvous and Docking Missions, lead a team composed of several Task Force members and technical advisors' to Russia with the goal of reviewing preparations and readiness for the upcoming international Space Station Phase 1 missions. In his directions to Gen. Stafford, Mr. Goldin requested that the review team focus its initial efforts on safety of flight issues for the following Phase 1A missions: the Soyuz TM-21 mission which will carry U.S. astronaut Dr. Norman Thagard and cosmonauts Lt. Col. Vladimir Dezhurov and Mr. Gennady Strekalov aboard a Soyuz spacecraft to the Mir Station; the Mir 18 Main Expedition during which Thagard and his fellow cosmonauts, Dezhurov and Strokalov, will spend approximately three months aboard the Mir Station; the STS-71 Space Shuttle mission which will perform the first Shuttle-Mir docking, carry cosmonauts Col. Anatoly SoloViev and Mr. Nikolai Budarin to the Mir Station, and return Thagard, Dezhurov, and Strekalov to Earth.

1995-01-01

269

Autonomous rendezvous and docking: A commercial approach to on-orbit technology validation  

NASA Technical Reports Server (NTRS)

The Space Automation and Robotics Center (SpARC), a NASA-sponsored Center for the Commercial Development of Space (CCDS), in conjunction with its corporate affiliates, is planning an on-orbit validation of autonomous rendezvous and docking (ARD) technology. The emphasis in this program is to utilize existing technology and commercially available components whenever possible. The primary subsystems that will be validated by this demonstration include GPS receivers for navigation, a video-based sensor for proximity operations, a fluid connector mechanism to demonstrate fluid resupply capability, and a compliant, single-point docking mechanism. The focus for this initial experiment will be expendable launch vehicle (ELV) based and will make use of two residual Commercial Experiment Transporter (COMET) service modules. The first COMET spacecraft will be launched in late 1992 and will serve as the target vehicle. The ARD demonstration will take place in late 1994, after the second COMET spacecraft has been launched. The service module from the second COMET will serve as the chase vehicle.

Tchoryk, Peter, Jr.; Dobbs, Michael E.; Conrad, David J.; Apley, Dale J.; Whitten, Raymond P.

1991-01-01

270

An overview of autonomous rendezvous and docking system technology development at General Dynamics  

NASA Technical Reports Server (NTRS)

The Centaur avionics suite is undergoing a dramatic modernization for the commercial, DoD Atlas and Titan programs. The system has been upgraded to the current state-of-the-art in ring laser gyro inertial sensors and Mil-Std-1750A processor technology. The Cruise Missile avionic system has similarly been evolving for many years. Integration of GPS into both systems has been underway for over five years with a follow-on cruise missile system currently in flight test. Rendezvous and Docking related studies have been conducted for over five years in support of OMV, CTV, and Advanced Upper Stages, as well as several other internal IR&D's. The avionics system and AR&D simulator demonstrated to the SATWG in November 1990 has been upgraded considerably under two IR&D programs in 1991. The Centaur modern avionics system is being flown in block upgrades which started in July of 1990. The Inertial Navigation Unit will fly in November of 1991. The Cruise Missile avionics systems have been fully tested and operationally validated in combat. The integrated AR&D system for space vehicle applications has been under development and testing since 1990. A Joint NASA / GD ARD&L System Test Program is currently being planned to validate several aspects of system performance in three different NASA test facilities in 1992.

Kuenzel, Fred

1991-01-01

271

A multiple-rendezvous, sample-return mission to two near-Earth asteroids  

NASA Astrophysics Data System (ADS)

We propose a dual-rendezvous mission, targeting near-Earth asteroids, including sample-return. The mission, Asteroid Sampling Mission (ASM), consists of two parts: (i) flyby and remote sensing of a Q-type asteroid, and (ii) sampling of a V-type asteroid. The targeted undifferentiated Q-type are found mainly in the near-Earth space, and to this date have not been the target of a space mission. We have chosen, for our sampling target, an asteroid from the basaltic class (V-type), as asteroids in this class exhibit spectral signatures that resemble those of the well-studied Howardite-Eucrite-Diogenite (HED) meteorite suite. With this mission, we expect to answer specific questions about the links between differentiated meteorites and asteroids, as well as gain further insight into the broader issues of early Solar System (SS) evolution and the formation of terrestrial planets. To achieve the mission, we designed a spacecraft with a dry mass of less than 3 tonnes that uses electric propulsion with a solar-electric power supply of 15 kW at 1 Astronomical Unit (AU). The mission includes a series of remote sensing instruments, envisages landing of the whole spacecraft on the sampling target, and employs an innovative sampling mechanism. Launch is foreseen to occur in 2018, as the designed timetable, and the mission would last about 10 years, bringing back a 150 g subsurface sample within a small re-entry capsule. This paper is a work presented at the 2008 Summer School Alpbach,"Sample return from the Moon, asteroids and comets" organized by the Aeronautics and Space Agency of the Austrian Research Promotion Agency. It is co-sponsored by ESA and the national space authorities of its Member and Co-operating States, with the support of the International Space Science Institute and Austrospace.

Duffard, R.; Kumar, K.; Pirrotta, S.; Salatti, M.; Kubínyi, M.; Derz, U.; Armytage, R. M. G.; Arloth, S.; Donati, L.; Duricic, A.; Flahaut, J.; Hempel, S.; Pollinger, A.; Poulsen, S.

2011-07-01

272

A Prediction Method of TV Camera Image for Space Manual-control Rendezvous and Docking  

NASA Astrophysics Data System (ADS)

Space manual-control rendezvous and docking (RVD) is a key technology for accomplishing the RVD mission in manned space engineering, especially when automatic control system is out of work. The pilot on chase spacecraft manipulates the hand-stick by the image of target spacecraft captured by TV camera. From the TV image, the relative position and attitude of chase and target spacecrafts can be shown. Therefore, the size, the position, the brightness and the shadow of the target on TV camera are key to guarantee the success of manual-control RVD. A method of predicting the on-orbit TV camera image at different relative positions and light conditions during the process of RVD is discussed. Firstly, the basic principle of capturing the image of cross drone on target spacecraft by TV camera is analyzed theoretically, based which the strategy of manual-control RVD is discussed in detail. Secondly, the relationship between the displayed size or position and the real relative distance of chase and target spacecrafts is presented, the brightness and reflection by the target spacecraft at different light conditions are decribed, the shadow on cross drone caused by the chase or target spacecraft is analyzed. Thirdly, a prediction method of on-orbit TV camera images at certain orbit and light condition is provided, and the characteristics of TV camera image during the RVD is analyzed. Finally, the size, the position, the brightness and the shadow of target spacecraft on TV camera image at typical orbit is simulated. The result, by comparing the simulated images with the real images captured by the TV camera on Shenzhou manned spaceship , shows that the prediction method is reasonable

Zhen, Huang; Qing, Yang; Wenrui, Wu

273

Rendezvous, Landing and Sample Return Mission to Jupiter Trojans by the Solar Power Sail  

NASA Astrophysics Data System (ADS)

JAXA/ISAS has been preparing for the Solar Power Sail mission, Japan’s first outer planet region exploration. Its precursor was successfully realized by IKAROS, the world's first deep space solar sail spacecraft, in 2010 between the Earth and Venus orbits. The Solar Power Sail is defined primarily as a technology demonstration mission; yet it will also present game-changing opportunities for both space astronomy and solar system exploration. The former will benefit the cruising operation, which will enable ”dust free” infrared astronomy beyond the cocoon of the zodiacal light to search for the first generation light of the Universe. Interplanetary-long baseline will allow gamma-ray burst observation to identify their source locations much more precise than ever. As for solar system exploration, the Solar Power Sail, which is not depended upon RTG technology, will offer the world's first possibility of rendezvous, landing and sample return from the outer planet region, i.e., in the Jupiter region and beyond. With this technology, we are aiming to visit Jupiter Trojan asteroids, one of the last uncharted frontiers of the Solar System. Jupiter Trojans may hold fundamental clues of the Solar System formation and revolution discussed by two competing hypotheses between the classic model and the planetary migration model. The former suggests that Trojan asteroids are mainly survivors of building blocks of the Jupiter system, while the latter claims that they must be intruders from outer regions after the planetary migration of gas planets settled. This paper outlines scientific objectives of Jupiter Trojan exploration, its mission design and major aspects of the spacecraft system, nature of candidate target asteroids, in-situ observation and lander instruments including optical camera, imaging spectrometer, high-resolution TOF mass spectrometer, and large-area dust counter, together with a strategy of the sample return option from the surface of a Trojan asteroid.

Yano, Hajime; Matsuura, Shuji; Mori, Osamu; Yonetoku, Daisuke; Nakamura, Ryosuke; Sekine, Yasuhito; Abe, Shinsuke

274

Mission analysis and guidance, navigation, and control design for rendezvous and docking phase of advanced reentry vehicle mission  

NASA Astrophysics Data System (ADS)

Advanced Reentry Vehicle (ARV) belongs to the family of vehicles designed to perform rendezvous and docking (RvD) with the International space station (ISS) [1]. Differently from its predecessor ATV (Automated Transfer Vehicle), the ARV will transport a reentry capsule, equipped with a heatshield and able to bring back cargo, experiments, or, as a possible future development, even crew, being this latter scenario very attracting in view of the Space Shuttle retirement. GMV, as subcontractor of EADS-Astrium Germany, is in charge of the RvD and departure mission analysis and GNC (Guidance, Navigation, and Control) design of ARV mission. This paper will present the main outcomes of the study.

Strippoli, L.; Colmenarejo, P.; Strauch, H.

2013-12-01

275

Concluding Report of Free-Spinning, Tumbling, and Recovery Characteristics of a 1/18-Scale Model of the Ryan X-13 Airplane, Coord. No. AF-199  

NASA Technical Reports Server (NTRS)

An investigation has been completed in the Langley 20-foot free-spinning tunnel on a l/18-scale model of the Ryan X-13 airplane to determine its spin, recovery, and tumbling characteristics, and to determine the minimum altitude from which a belly landing could be made in case of power failure in hovering flight. Model spin tests were conducted with and without simulated engine rotation. Tests without simulated engine rotation indicated two types of spins: one, a slightly oscillatory flat spin; and the other, a violently oscillatory spin. Tests with simulated engine rotation indicated that spins to the left were fast rotating and steep and those to the right were slow rotating and flat. The optimum technique for recovery is reversal of the rudder to against the spin and simultaneous movement of the ailerons to full with the spin followed by movement of the elevators to neutral after the spin rotation ceases. Tumbling tests made on the model indicated that although the Ryan X-13 airplane will not tumble in the ordinary sense (end-over-end pitching motion), it may instead tend to enter a wild gyrating'motion. Tests made to simulate power failure in hovering flight by dropping the model indicated that the model entered what appeared to be a right spin. An attempt should be made to stop this motion immediately by moving the rudder to oppose the rotation (left pedal), moving the ailerons to with the spin (stick right), and moving the stick forward after the spin rotation ceases to obtain flying speed for pullout. The minimum altitude required for a belly landing in case of power failure in hovering flight was indicated to be about 4,200 feet.

Bowman, James S., Jr.

1957-01-01

276

NASA's Automated Rendezvous and Docking/Capture Sensor Development and Its Applicability to the GER  

NASA Technical Reports Server (NTRS)

This paper will address how a common Automated Rendezvous and Docking/Capture (AR&D/C) sensor suite can support Global Exploration Roadmap (GER) missions, and discuss how the model of common capability development to support multiple missions can enable system capability level partnerships and further GER objectives. NASA has initiated efforts to develop AR&D/C sensors, that are directly applicable to GER. NASA needs AR&D/C sensors for both the robotic and crewed segments of the Asteroid Redirect Mission (ARM). NASA recently conducted a commonality assessment of the concept of operations for the robotic Asteroid Redirect Vehicle (ARV) and the crewed mission segment using the Orion crew vehicle. The commonality assessment also considered several future exploration and science missions requiring an AR&D/C capability. Missions considered were asteroid sample return, satellite servicing, and planetary entry, descent, and landing. This assessment determined that a common sensor suite consisting of one or more visible wavelength cameras, a three-dimensional LIDAR along with long-wavelength infrared cameras for robustness and situational awareness could be used on each mission to eliminate the cost of multiple sensor developments and qualifications. By choosing sensor parameters at build time instead of at design time and, without having to requalify flight hardware, a specific mission can design overlapping bearing, range, relative attitude, and position measurement availability to suit their mission requirements with minimal nonrecurring engineering costs. The resulting common sensor specification provides the union of all performance requirements for each mission and represents an improvement over the current systems used for AR&D/C today. NASA's AR&D/C sensor development path could benefit the International Exploration Coordination Group (ISECG) and support the GER mission scenario by providing a common sensor suite upon which GER objectives could be achieved while minimizing development costs. The paper will describe the concepts of operations of these missions and how the common sensors are utilized by each mission. It will also detail the potential partnerships and contribution of the International community in the development of this common AR&D/C sensor suite.

Hinkel, Heather; Cryan, Scott; DSouza, Christopher; Strube, Matthew

2014-01-01

277

Tumble Wing Walkalong Glider  

NSDL National Science Digital Library

In this physics activity (page 2 of the PDF), learners will construct their own walkalong glider. They will explore how air, though invisible, surrounds and affects other objects. Learners will discover that air is made up of molecules that exert pressure on objects. Though this activity was created as a pre-visit for a traveling science show, it makes a great stand-alone activity as well.

Cosi

2009-01-01

278

Spectral analysis and compositing techniques for the Near Earth Asteroid Rendezvous (NEAR Shoemaker), X-ray and Gamma-Ray Spectrometers (XGRS)  

Microsoft Academic Search

An X-ray and Gamma-Ray Spectrometer (XGRS) is on board the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433 Eros. The Eros asteroid is highly oblate and irregular in shape. As a result, analysis methodologies are in many ways a divergence from comparable techniques. Complex temporal, spatial and instrument performance relationships

T. P McClanahan; J. I. Trombka; L. R Nittler; W. V. Boynton; J. Bruckner; S. W Squyres; L. G Evans; J. S Bhangoo; P. E Clark; S. R Floyd; E. McCartney; I. Mikheeva; R. D Starr

2001-01-01

279

An Investigation of Multipath Effects on the GPS System During Auto-Rendezvous and Capture  

NASA Technical Reports Server (NTRS)

The proposed use of a Cargo Transport Vehicle (CTV) to carry hardware to the Space Station Freedom (SSF) during the construction phase of the SSF project requires remote maneuvering of the CTV. The CTV is not a manned vehicle. Obtaining the relative positions of the CTV and SSF for remote auto-rendezvous and capture (AR&C) scenarios will rely heavily on the Global Positioning System (GPS). The GPS system is expected to guide the CTV up to a distance of 100 to 300 meters from the SSF. At some point within this range, an optical docking system will take over the remote guidance for capture. During any remote guidance by GPS it is possible that significant multipath signals may be caused by large objects in the vicinity of the module being remotely guided. This could alter the position obtained by the GPS system from the actual position. Due to the nature of the GPS signals, it has been estimated that if the difference in distance between the Line of Sight (LOS) path and the multipath is greater than 300 meters, the GPS system is capable of discriminating between the direct signal and the reflected (or multipath) signal. However, if the path difference is less than 300 meters, one must be concerned. This report details the work accomplished by the Electromagnetic Simulations Laboratory at Marquette University over the period December 1993 to May 1995. This work is an investigation of the strength and phase of a multipath signal arriving at the CTV relative to the direct or line of sight (LOS) signal. The signal originates at a GPS satellite in half geo-stationary orbit and takes two paths to the CTV: (1) the direct or LOS path from the GPS satellite to the CTV; and (2) a scattered path from the GPS satellite to the SSF module and then to the CTV. The scattering from a cylinder has been computed using the physical optics approximation for the current. No other approximations or assumptions have been made including no assumptions regarding the far field or Fresnel field approximations. The integrations required to obtain the scattered field have been computed numerically using an N dimensional Romberg integration. The total scattered electric field is then projected onto the RCP component in the direction of propagation only. The direct or line of sight signal is then used to compute the relative strength and phase of the scattered field. The trajectory of the CTV has been parameterized into 4,214 points that are calculated for each of the geometries investigated. The motion of the CTV between points is small enough for the magnitude data (dB down from direct signal) to appear very smooth; however, because of the distances and wavelengths involved, the phase of the scattered field relative to the direct signal varies very rapidly.

Richie, James E.; Forest, Francis W.

1995-01-01

280

Laser rangefinder for the near-earth asteroid rendezvous (NEAR) mission  

NASA Astrophysics Data System (ADS)

The near-earth asteroid rendezvous (NEAR) mission is the first of the NASA discovery programs. Discovery-class programs emphasize small, low-cost, quick turnaround space missions that provide significant science returns. The NEAR spacecraft and ground control system are currently being developed and tested at the Applied Physics Laboratory (APL). The NEAR spacecraft will orbit, 433 Eros, possibly the most studied of the near-Earth asteroids. Subsequent to a 3-year cruise, the NEAR spacecraft is inserted into a 50-km-altitude orbit about Eros for 1 year to permit data collection in the infrared, visible, x-ray and gamma-ray regions. One instrument, the NEAR laser rangefinder (NLR), will provide altimetry data useful in characterizing the geophysical nature of Eros. In addition, ranging data from the NLR will support navigation functions associated with spacecraft station-keeping and orbit maintenance. The NLR instrument uniquely applies several technologies for use in space. Our configuration uses a direct-detection, bistatic design employing a gallium arsenide (GaAs) diode-pumped Cr:Nd:YAG laser for the 1.064-micrometer transmitter and an enhanced-silicon avalanche-photodiode (APD) detector for the receiver. Transmitter pulse energy provides the required signal-to-noise power ratio, SNRp, for reliable operation at 50 km. The selected APD exhibited low noise, setting the level achievable for noise equivalent power, NEP, by the receiver. The lithium-niobate (LiNbO3) Q-switched transmitter emits 12-ns pulses at 15.3 mJ/pulse, permitting reliable NLR operation beyond the required 50-km altitude. Cavity aperturing and a 9.3X Galilean telescope reduce beam divergence for high spatial sampling of Eros's surface. Our receiver design is an f/3.4 Dall-Kirkham Cassegrain with a 7.62-cm clear aperture -- we emphasized receiver aperture area, Arx, over transmitter power, Pt, in our design based on the range advantage attainable according to the simplified range equation, Rmax equals [(Pt(rho) BArx)/(SNRp NEP)]1/2. Asteroid reflectivity, (rho) B, is estimated to be 0.05 at our wavelength. A reasonable power signal- to-noise ratio for reliable operation, SNRp, was assumed. To minimize our noise equivalent power, NEP, we carefully designed and selected the receiver components. The receiver circuit uses leading-edge detection of the laser backscatter. Our detector circuit is an enhanced-silicon APD hybrid using a video amplifier, an integrating Bessel filter, and a high- speed programmable threshold comparator. We accomplish time-of-flight (TOF) measurements digitally with an APL-designed GaAs application-specific integrated circuit. A radiation-hardened FORTH microprocessor controls range gating, data collection and formatting, and operational modes. Implementation of control and data communications between the spacecraft and rangefinder uses the MIL-STD 1553-bus architecture. Functional testing and calibration indicate exceptional performance; return power levels were reliably detected over several thresholds with 71-dB attenuation, while observed range jitter was equivalent to the resolution determined by the TOF GaAs chip (31.5 cm). This paper discusses NLR performance requirements, design implementation, and qualification testing. It also provides preliminary results from calibration and performance testing.

Cole, Timothy D.; Boies, Mark T.; El-Dinary, Ashruf S.; Reiter, R. Alan; Rodriguez, Daniel E.; Heins, Robert J.; Le, Binh Q.; Moore, Robert C.; Grote, Michael G.; Culpepper, Charles; Stillman, Lee

1995-12-01

281

Rosetta rendezvous and CONSERT operations in 2014: A chimeric surface model of 67P/Churyumov Gerasimenko  

NASA Astrophysics Data System (ADS)

In 2014 the European Space Agency's Rosetta probe will rendezvous with the comet 67P/Churyumov Gerasimenko (67P) and the Philae Lander will land on the surface of the nucleus. Following the landing, the COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) radar will perform the tomography of the nucleus by measuring radiowave propagation through the comet between the Lander and the orbiter. Preparation for these operations, in particular the development and validation of simulation software, requires a shape model of the surface of 67P. The complexity of this model should reflect the environmental conditions that will be found in 2014. In this paper, we show that existing models of 67P are not of a sufficiently high resolution to constitute interesting test cases. Following a review of current shape models for other comets, we propose a composite which is a hybrid of the 67P and 81P/Wild 2 models.

Herique, Alain; Lasue, Jéremie; Rogez, Yves; Zine, Sonia; Kofman, Wlodek

2012-07-01

282

Electron Spin Relaxation Rates for Semiquinones between 25 and 295 K in Glass-Forming Solvents  

PubMed Central

Electron spin lattice relaxation rates for five semiquinones (2,5-di-t-butyl-1,4-benzosemiquinone, 2,5-di-t-amyl-1,4-benzosemiquinone, 2,5-di-phenyl-1,4-benzosemiquinone, 2,6-di-t-butyl-1,4-benzosemiquinone, tetrahydroxy-1,4-benzosemiquione) were studied by long-pulse saturation recovery EPR in 1:4 glycerol:ethanol, 1:1 glycerol:ethanol, and triethanolamine between 25 and 295 K. Although the dominant process changes with temperature, relaxation rates vary smoothly with temperature, even near the glass transition temperatures, and could be modeled as the sum of contributions that have the temperature dependence that is predicted for the direct, Raman, local mode and tumbling dependent processes. At 85 K, which is in a temperature range where the Raman process dominates, relaxation rates along the gxx (g~2.006) and gyy (g~2.005) axes are about 2.7 to 1.5 times faster than along the gzz axis (g = 2.0023). In highly viscous triethanolamine, contributions from tumbling-dependent processes are negligible. At temperatures above 100 K relaxation rates in triethanolamine are unchanged between X-band (9.5 GHz) and Q-band (34 GHz), so the process that dominates in this temperature interval was assigned as a local mode rather than a thermally-activated process. Because the largest proton hyperfine couplings are only 2.2 G, spin rotation makes a larger contribution than tumbling-dependent modulation of hyperfine anisotropy. Since g anisotropy is small, tumbling dependent modulation of g anisotropy make a smaller contribution than spin rotation at X-band. Although there was negligible impact of methyl rotation on T1, rotation of t-butyl or t-amyl methyl groups enhances spin echo dephasing between 85 and 150 K. PMID:19223213

Kathirvelu, Velavan; Sato, Hideo; Eaton, Sandra S.; Eaton, Gareth R.

2009-01-01

283

Study of effects of uncertainties on comet and asteroid encounter and contact guidance requirements. Part 1: Guidance and navigation studies. [development of navigation and guidance techniques for space rendezvous  

NASA Technical Reports Server (NTRS)

A guidance algorithm that provides precise rendezvous in the deterministic case while requiring only relative state information is developed. A navigation scheme employing only onboard relative measurements is built around a Kalman filter set in measurement coordinates. The overall guidance and navigation procedure is evaluated in the face of measurement errors by a detailed numerical simulation. Results indicate that onboard guidance and navigation for the terminal phase of rendezvous is possible with reasonable limits on measurement errors.

1973-01-01

284

Magnetometer-Only Attitude and Rate Estimates for Spinning Spacecraft  

NASA Technical Reports Server (NTRS)

A deterministic algorithm and a Kalman filter for gyroless spacecraft are used independently to estimate the three-axis attitude and rates of rapidly spinning spacecraft using only magnetometer data. In-flight data from the Wide-Field Infrared Explorer (WIRE) during its tumble, and the Fast Auroral Snapshot Explorer (FAST) during its nominal mission mode are used to show that the algorithms can successfully estimate the above in spite of the high rates. Results using simulated data are used to illustrate the importance of accurate and frequent data.

Challa, M.; Natanson, G.; Ottenstein, N.

2000-01-01

285

Mechanisms and Rates of Bacterial Colonization of Sinking Aggregates  

PubMed Central

Quantifying the rate at which bacteria colonize aggregates is a key to understanding microbial turnover of aggregates. We used encounter models based on random walk and advection-diffusion considerations to predict colonization rates from the bacteria's motility patterns (swimming speed, tumbling frequency, and turn angles) and the hydrodynamic environment (stationary versus sinking aggregates). We then experimentally tested the models with 10 strains of bacteria isolated from marine particles: two strains were nonmotile; the rest were swimming at 20 to 60 ?m s?1 with different tumbling frequency (0 to 2 s?1). The rates at which these bacteria colonized artificial aggregates (stationary and sinking) largely agreed with model predictions. We report several findings. (i) Motile bacteria rapidly colonize aggregates, whereas nonmotile bacteria do not. (ii) Flow enhances colonization rates. (iii) Tumbling strains colonize aggregates enriched with organic substrates faster than unenriched aggregates, while a nontumbling strain did not. (iv) Once on the aggregates, the bacteria may detach and typical residence time is about 3 h. Thus, there is a rapid exchange between attached and free bacteria. (v) With the motility patterns observed, freely swimming bacteria will encounter an aggregate in <1 day at typical upper-ocean aggregate concentrations. This is faster than even starving bacteria burn up their reserves, and bacteria may therefore rely solely on aggregates for food. (vi) The net result of colonization and detachment leads to a predicted equilibrium abundance of attached bacteria as a function of aggregate size, which is markedly different from field observations. This discrepancy suggests that inter- and intraspecific interactions among bacteria and between bacteria and their predators may be more important than colonization in governing the population dynamics of bacteria on natural aggregates. PMID:12147501

Ki?rboe, Thomas; Grossart, Hans-Peter; Ploug, Helle; Tang, Kam

2002-01-01

286

The Space Operations Simulation Center (SOSC) and Closed-Loop Hardware Testing for Orion Rendezvous System Design  

NASA Technical Reports Server (NTRS)

The exploration goals of Orion / MPCV Project will require a mature Rendezvous, Proximity Operations and Docking (RPOD) capability. Ground testing autonomous docking with a next-generation sensor such as the Vision Navigation Sensor (VNS) is a critical step along the path of ensuring successful execution of autonomous RPOD for Orion. This paper will discuss the testing rationale, the test configuration, the test limitations and the results obtained from tests that have been performed at the Lockheed Martin Space Operations Simulation Center (SOSC) to evaluate and mature the Orion RPOD system. We will show that these tests have greatly increased the confidence in the maturity of the Orion RPOD design, reduced some of the latent risks and in doing so validated the design philosophy of the Orion RPOD system. This paper is organized as follows: first, the objectives of the test are given. Descriptions of the SOSC facility, and the Orion RPOD system and associated components follow. The details of the test configuration of the components in question are presented prior to discussing preliminary results of the tests. The paper concludes with closing comments.

Milenkovic, Zoran; DSouza, Christopher; Huish, David; Bendle, John; Kibler, Angela

2012-01-01

287

Thermo-physical properties of 162173 (1999 JU3), a potential flyby and rendezvous target for interplanetary missions  

NASA Astrophysics Data System (ADS)

Context. Near-Earth asteroid 162173 (1999 JU3) is a potential flyby and rendezvous target for interplanetary missions because of its easy-to-reach orbit. The physical and thermal properties of the asteroid are relevant for establishing the scientific mission goals and also important in the context of near-Earth object studies in general. Aims: Our goal was to derive key physical parameters such as shape, spin-vector, size, geometric albedo, and surface properties of 162173 (1999 JU3). Methods: With three sets of published thermal observations (ground-based N-band, Akari IRC, Spitzer IRS), we applied a thermophysical model to derive the radiometric properties of the asteroid. The calculations were performed for the full range of possible shape and spin-vector solutions derived from the available sample of visual lightcurve observations. Results: The near-Earth asteroid 162173 (1999 JU3) has an effective diameter of 0.87 ± 0.03 km and a geometric albedo of 0.070 ± 0.006. The ?2-test reveals a strong preference for a retrograde sense of rotation with a spin-axis orientation of ?ecl = 73°, ?ecl = -62° and Psid = 7.63 ± 0.01 h. The most likely thermal inertia ranges between 200 and 600 J m-2 s-0.5 K-1, about a factor of 2 lower than the value for 25143 Itokawa. This indicates that the surface lies somewhere between a thick-dust regolith and a rock/boulder/cm-sized, gravel-dominated surface like that of 25143 Itokawa. Our analysis represents the first time that shape and spin-vector information has been derived from a combined data set of visual lightcurves (reflected light) and mid-infrared photometry and spectroscopy (thermal emission).

Müller, T. G.; ?urech, J.; Hasegawa, S.; Abe, M.; Kawakami, K.; Kasuga, T.; Kinoshita, D.; Kuroda, D.; Urakawa, S.; Okumura, S.; Sarugaku, Y.; Miyasaka, S.; Takagi, Y.; Weissman, P. R.; Choi, Y.-J.; Larson, S.; Yanagisawa, K.; Nagayama, S.

2011-01-01

288

Cosmic Ray Induced Degradation in X-Ray Detectors On Board the Near Earth Asteroid Rendezvous Spacecraft  

NASA Technical Reports Server (NTRS)

The Near-Earth Asteroid Rendezvous (NEAR) mission is the first in NASA's new Discovery Program to explore the solar system. Launched in February 1996, the NEAR spacecraft will take a long cruise flight arriving at the asteroid 433 Eros in January 1999 for a one year orbiting survey operation. This long exposure to the space environment has already proven to be an additional complication for the x-ray spectrometer. The asteroid pointing detectors for the x-ray spectrometer are three gas-filled proportional counters with resolving power in the range of 1 keV. Therefore, to resolve the important but closely spaced magnesium, aluminum and silicon k alpha lines( 1.255, 1.487, 1.739 keV respectively), magnesium and aluminum balanced filters are used on two of the detectors. The x-ray florescence from the surface of Eros is stimulated by solar x-rays. A proportional counter and a silicon PIN detector are used to monitor the solar incident x-ray flux. The proportional counters are single wire gas filled beryllium lined steel tubes operating at about 1100 volt. The 25 cm(exp 2) optical window is one mil. thick beryllium. To define the detector's active region, two boron nitride disks were incorporated in the tube just outside window area. It appears from the space flight data that the space environment is creating a charge on these boron nitride disks which ultimately distorts the tube gain and resolution. This broadening of the photo peak makes it more difficult to identify weak peaks and so degrades the statistical accuracy for some very important elements such as sulfur, calcium and iron (2.307, 3.690, 6.403 keV respectively). If the broadening is severe enough in the low energy region, counts will be lost as the photo peak spreads below the lower level discriminator (0.7 keV).

Floyd, S. R.; Trombka, J. I.; Goldsten, J. O.; Fiore, E. M.

1997-01-01

289

Technology Development of Automated Rendezvous and Docking/Capture Sensors and Docking Mechanism for the Asteroid Redirect Crewed Mission  

NASA Technical Reports Server (NTRS)

This paper will describe the technology development efforts NASA has underway for Automated Rendezvous and Docking/Capture (AR&D/C) sensors and a docking mechanism and the challenges involved. The paper will additionally address how these technologies will be extended to other missions requiring AR&D/C whether robotic or manned. NASA needs AR&D/C sensors for both the robotic and crewed segments of the Asteroid Redirect Mission (ARM). NASA recently conducted a commonality assessment of the concept of operations for the robotic Asteroid Redirect Vehicle (ARV) and the crewed mission segment using the Orion crew vehicle. The commonality assessment also considered several future exploration and science missions requiring an AR&D/C capability. Missions considered were asteroid sample return, satellite servicing, and planetary entry, descent, and landing. This assessment determined that a common sensor suite consisting of one or more visible wavelength cameras, a threedimensional LIDAR along with long-wavelength infrared cameras for robustness and situational awareness could be used on each mission to eliminate the cost of multiple sensor developments and qualifications. By choosing sensor parameters at build time instead of at design time and, without having to requalify flight hardware, a specific mission can design overlapping bearing, range, relative attitude, and position measurement availability to suit their mission requirements with minimal nonrecurring engineering costs. The resulting common sensor specification provides the union of all performance requirements for each mission and represents an improvement over the current systems used for AR&D/C today. These sensor specifications are tightly coupled to the docking system capabilities and requirements for final docking conditions. The paper will describe NASA's efforts to develop a standard docking system for use across NASA human spaceflight missions to multiple destinations. It will describe the current design status and the considerations and technologies involved in developing this docking mechanism.

Hinkel, Heather; Cryan, Scott; Zipay, John; Strube, Matthew

2015-01-01

290

THERMODYNAMIC AND MESOSCOPIC MODELING OF TUMBLING NEMATICS, OF SHEAR-THICKENING FLUIDS AND OF STICK-SLIP-LIKE FLOW BEHAVIOR  

Microsoft Academic Search

Shear thickening, i.e. the increase of the viscosity with increasing shear rate as it occurs in dense colloidal dispersions and polymeric fluids is an intriguing phenom- enon with a considerable potential for technical applications. The theoretical description of this phenomenon is patterned after the thermodynamic and mesoscopic modeling of the orientational dynamics and the flow behavior of liquid crystals in

SIEGFRIED HESS; SEBASTIAN HEIDENREICH; PATRICK ILG; CHRIS GODDARD; ORTWIN HESS

291

Spontaneous Rupture of Superficial Femoral Artery Repaired with Endovascular Stent-Grafting with use of Rendez-Vous Technique, Followed by Delayed Infection  

SciTech Connect

This is the case of a 72-year-old man with lower limb ischemia due to spontaneous rupture of nonaneurysmal superficial femoral artery that developed into thigh hematoma. After failure of a Fogarty revascularization, an emergency endovascular procedure was performed to restore the arterial continuity. A rendezvous procedure was performed with a double femoral and popliteal approach and two covered stent-grafts were deployed. Patient's clinical conditions immediately improved, but 4 months later the stent-grafts were surgically removed for infection and exteriorization. A femoropopliteal bypass was performed. After 1 year follow-up, the patient is in good clinical condition.

Fanelli, Fabrizio, E-mail: fabrizio.fanelli@uniroma1.it; Cannavale, Alessandro [University of Rome 'Sapienza,', Department of Radiological Sciences, Vascular and Interventional Radiology Unit (Italy)] [University of Rome 'Sapienza,', Department of Radiological Sciences, Vascular and Interventional Radiology Unit (Italy); Gazzetti, Marianna [Sapienza University of Rome 'Sapienza,', Department of Surgery Paride Stefanini, Vascular Surgery Division, Policlinico Umberto I (Italy)] [Sapienza University of Rome 'Sapienza,', Department of Surgery Paride Stefanini, Vascular Surgery Division, Policlinico Umberto I (Italy); Fantozzi, Cristiano; Taurino, Maurizio [University of Rome 'Sapienza,', Department of Vascular Surgery (Italy)] [University of Rome 'Sapienza,', Department of Vascular Surgery (Italy); Speziale, Francesco [Sapienza University of Rome 'Sapienza,', Department of Surgery Paride Stefanini, Vascular Surgery Division, Policlinico Umberto I (Italy)] [Sapienza University of Rome 'Sapienza,', Department of Surgery Paride Stefanini, Vascular Surgery Division, Policlinico Umberto I (Italy)

2013-02-15

292

'Run-and-tumble' or 'look-and-run'? A mechanical model to explore the behavior of a migrating amoeboid cell.  

PubMed

Single cell migration constitutes a fundamental phenomenon involved in many biological events. Amoeboid cells are single cell organisms that migrate in a cyclic manner like worms. In this paper, we propose a 3D finite element model of an amoeboid cell migrating over a 2D surface. In particular, we focus on the mechanical aspect of the problem. The cell is able to generate cyclic active deformations, such as protrusion and contraction, in any direction. The progression of the cell is governed by a tight synchronization between the adhesion forces, which are alternatively applied at the front and at the rear edges of the cell, and the protrusion-contraction phases of the cell body. Finally, two important aspects have been taken into account: (1) the external stimuli in response to which the cell migrates (e.g. need to feed, morphogenetic events, normal or abnormal environment cues), (2) the heterogeneity of the 2D substrate (e.g. obstacles, rugosity, slippy regions) for which two distinct approaches have been evaluated: the 'run-and-tumble' strategy and the 'look-and-run' strategy. Overall, the results show a good agreement with respect to the experimental observations and the data from the literature (e.g. velocity and strains). Therefore, the present model helps, on one hand, to better understand the intimate relationship between the deformation modes of a cell and the adhesion strength that is required by the cell to crawl over a substrate, and, on the other hand, to put in evidence the crucial role played by mechanics during the migration process. PMID:22726805

Allena, Rachele; Aubry, Denis

2012-08-01

293

Light scattering observations and simulations, as hints about the media encountered by future rendezvous missions to comets and asteroids  

NASA Astrophysics Data System (ADS)

The success of future rendezvous mission to comets (i.e. Rosetta, which will explore the innermost coma of 67P/Churyumov-Gerasimenko, before deploying a lander on its nucleus in 2014) and asteroids (e.g. Marco-Polo candidate mission for ESA Cosmic Vision) require some understanding of the physical properties of the dust particles encountered in the coma (if any) and on the solid surface. Analysis of observations of the linear polarization of solar light scattered by such media may provide clues to their properties [1]. The polarization is actually a dimension-less ratio, which only varies with the geometry of the observations (i.e. phase angle), with the wavelength, and with the properties of the scattering medium. Comparisons between the shapes of the polarimetric phase curves of asteroids [2] and comets [3] provide a classification with respect to the dust properties. As far as asteroids are concerned, this classification is reminiscent of the taxonomic classes, and more information is expected from detailed studies of the wavelength dependence. As far as comets are concerned, an extensive programme of numerical and laboratory simulations with various irregular compact grains and aggregates has been developed in the past years [4,5]. Comparisons of the results with observations (tentatively on a large range of phase angles and wavelengths) have allowed us to suggest that cometary dust particles are built of both very fluffy aggregates and of more compact grains, with significant proportions of both rather transparent silicates and absorbing materials [6]. These estimations are confirmed by the analysis of Stardust samples, with, e.g. evidence for dense grains and aggregates with low bulk density within the coma of comet Wild 2 [7]. It may thus be concluded that the analysis of remote light scattering observations allows us to infer some properties of the scattering media, to point out some similarities and discrepancies between small solar system bodies, and to contribute to the success of future space missions. [1] Levasseur-Regourd and Hadamcik, J. Quant. Spectros. Radiat. Transfer 79, 903-910, 2003. [2] Pentill¨ et al., Astron. Astrophys. 432, 1081-1090, 2005. [3] Levasseur-Regourd a et al., Astron. Astrophys. 313, 327-333, 1996. [4] Lasue and Levasseur-Regourd, J. Quant. Spectros. Radiat. Transfer 100, 220-236, 2006. [5] Hadamcik et al., Icarus 190, 660-671, 2007. [6] Levasseur-Regourd et al., Planet. Space Sci. 55, 1010-1020, 2007. [7] H¨rz et al., Science o 314, 1716-1719 (2006).

Levasseur-Regourd, Anny-Chantal

294

Source : Philippe Poirrier, Culture populaire et politique culturelle en France : un rendez-vous manqu ? dans Thomas ANTONIETTI, Bruno MEIER et Katrin RIEDER (dir.), Retour vers le prsent. La culture populaire en Suisse, Baden,  

E-print Network

Source : Philippe Poirrier, « Culture populaire et politique culturelle en France : un rendez culture populaire en Suisse, Baden, Hier+jetzt, Verlag für Kultur und Geschichte, 2008, p. 176-183. Culture populaire et politique culturelle en France : un rendez-vous manqué ? Comment la politique

Paris-Sud XI, Université de

295

Noncooperative rendezvous radar system  

NASA Technical Reports Server (NTRS)

A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

1974-01-01

296

Star Library: Random Rendezvous  

NSDL National Science Digital Library

This activity leads students to appreciate the usefulness of simulations for approximating probabilities. It also provides them with experience calculating probabilities based on geometric arguments and using the bivariate normal distribution. We have used it in courses in probability and mathematical statistics, as well as in an introductory statistics course at the post-calculus level. Students are expected to approximate the solution through simulation before solving it exactly. They are also expected to employ graphical as well as algebraic problem-solving strategies, in addition to their simulation analyzes. Finally, students are asked to explain intuitively why it makes sense for the probabilities to change as they do.

Chance, Beth; Rossman, Allan

2009-06-04

297

Tumbling motions of NH2(CH3)2 ions in [NH2(CH3)2]2ZnCl4 studied using 1H MAS NMR and 13C CP/MAS NMR  

NASA Astrophysics Data System (ADS)

The structure and the phase transition temperatures of [NH2(CH3)2]2ZnCl4 were determined using X-ray diffraction and DSC, respectively. The temperature dependence of chemical shifts and the spin-lattice relaxation time T1? in the rotating frame were measured for the 1H and 13C nuclei in [NH2(CH3)2]2ZnCl4. From these results, it was observed that the structural change by chemical shifts does not occur with temperature. However, T1? for 1H and 13C in [NH2(CH3)2]2ZnCl4 showed a minimum, and it is apparent that both T1? values are governed by the same tumbling motions. The activation energies of tumbling motions for 1H and 13C are nearly the same owing to the connection between CH3 and NH2 ions in the [NH2(CH3)2]+ group.

Kim, Nam Hee; Choi, Jae Hun; Lim, Ae Ran

2014-12-01

298

Investigation of Spinning and Tumbling Characteristics of a 1/20-Scale Model of the Consolidated Vultee XFY-1 Airplane in the Free-Spinning Tunnel, TED No. NACA DE 370  

NASA Technical Reports Server (NTRS)

An investigation has been conducted in the Langley 20-foot free-spinning tunnel on a l/20-scale model of the Consolidated Vultee XFY-1 airplane with a windmilling propeller simulated to determine the effects of control setting and movements upon the erect spin and recovery characteristics for a range of airplane-loading conditions. The effects on the model's spin-recovery characteristics of removing the lower vertical tail, removing the gun pods, and fixing the rudders at neutral were also investigated briefly. The investigation included determination of the size parachute required for emergency recovery from demonstration spins. The tumbling tendencies of the model were also investigated. Brief static force tests were made to determine the aerodynamic characteristics in pitch at high angles of attack. The investigation indicated that the spin and recovery characteristics of the airplane with propeller windmilling will be satisfactory for all loading conditions if recovery is attempted by full rudder reversal accompanied by simultaneous movement of the stick laterally to full with the spin (stick right in a right spin) and longitudinally to neutral. Inverted spins should be satisfactorily terminated by fully reversing the rudder followed immediately by moving the stick laterally towards the forward rudder pedal and longitudinally to neutral. Removal of the gun pods or fixing the rudders at neutral will not adversely affect the airplane's spin-recovery characteristics, but removal of the lower vertical tail will result in unsatisfactory spin-recovery characteristics. The model-test results showed that a 13.3-foot wing-tip conventional parachute (drag coefficient approximately 0.7) should be effective as an emergency spin-recovery device during demonstration spins of the airplane. It was indicated that the airplane should not tumble and that no unusual longitudinal-trim characteristics should be obtained for the center-of-gravity positions investigated.

Lee, Henry A.

1952-01-01

299

Rough and Tumble at Reform Party Convention  

NSDL National Science Digital Library

To be sure, this convention has not been scripted. Simmering tensions within the Reform Party boiled over this week at the party's convention in Long Beach, California. Followers of party-founder Ross Perot, who initially invited Patrick Buchanan to join the party because of Buchanan's national name recognition, had grown increasingly frustrated with what many see as the hijacking of the party's state organizations by Buchanan and his allies. The party has traditionally avoided divisive social or moral issues such as abortion and gay rights, issues central to Buchanan's hard-right agenda. After months of maneuvering and party infighting, Buchanan arrived in Long Beach with the most delegates. Two days of confusion and conflict followed, after which the party split in two, with Perot followers setting up their own convention next door and nominating John Hagelin, a physicist and Transcendental Mediation advocate who previously ran twice for president on the Natural Law Party ticket. At stake is $12.6 million in federal matching funds. While both candidates will no doubt declare that they have the nomination, the disposal of the money will most likely be decided by federal election officials. The Perot-Hagelin wing has already filed a complaint with the Federal Elections Commission contending that Buchanan's forces rigged the nomination process. Whichever candidate is awarded the funds, his strategy will almost certainly be to spend the bulk of the money in September, hoping to secure a spot in upcoming the presidential debates.

De Nie, Michael W.

300

Autonomous Capture of a Tumbling Satellite  

E-print Network

in the success of space mis- sions. The Shuttle Remote Manipulator System, also known as Canadarm, has made Space Station ISS , Canadarm2 has been a crucial element in all construc- tion activities. Its sibling

Rekleitis, Ioannis

301

Energy Rating  

E-print Network

Consistent, accurate, and uniform ratings based on a single statewide rating scale Reasonable estimates of potential utility bill savings and reliable recommendations on cost-effective measures to improve energy efficiency Training and certification procedures for home raters and quality assurance procedures to promote accurate ratings and to protect consumers Labeling procedures that will meet the needs of home buyers, homeowners, renters, the real estate industry, and mortgage lenders with an interest in home energy ratings

Cabec Conference; Rashid Mir P. E

2009-01-01

302

A Proposed Strategy for the U.S. to Develop and Maintain a Mainstream Capability Suite ("Warehouse") for Automated/Autonomous Rendezvous and Docking in Low Earth Orbit and Beyond  

NASA Technical Reports Server (NTRS)

The ability of space assets to rendezvous and dock/capture/berth is a fundamental enabler for numerous classes of NASA fs missions, and is therefore an essential capability for the future of NASA. Mission classes include: ISS crew rotation, crewed exploration beyond low-Earth-orbit (LEO), on-orbit assembly, ISS cargo supply, crewed satellite servicing, robotic satellite servicing / debris mitigation, robotic sample return, and robotic small body (e.g. near-Earth object, NEO) proximity operations. For a variety of reasons to be described, NASA programs requiring Automated/Autonomous Rendezvous and Docking/Capture/Berthing (AR&D) capabilities are currently spending an order-of-magnitude more than necessary and taking twice as long as necessary to achieve their AR&D capability, "reinventing the wheel" for each program, and have fallen behind all of our foreign counterparts in AR&D technology (especially autonomy) in the process. To ensure future missions' reliability and crew safety (when applicable), to achieve the noted cost and schedule savings by eliminate costs of continually "reinventing the wheel ", the NASA AR&D Community of Practice (CoP) recommends NASA develop an AR&D Warehouse, detailed herein, which does not exist today. The term "warehouse" is used herein to refer to a toolbox or capability suite that has pre-integrated selectable supply-chain hardware and reusable software components that are considered ready-to-fly, low-risk, reliable, versatile, scalable, cost-effective, architecture and destination independent, that can be confidently utilized operationally on human spaceflight and robotic vehicles over a variety of mission classes and design reference missions, especially beyond LEO. The CoP also believes that it is imperative that NASA coordinate and integrate all current and proposed technology development activities into a cohesive cross-Agency strategy to produce and utilize this AR&D warehouse. An initial estimate indicates that if NASA strategically coordinates the development of a robust AR&D capability across the Agency, the cost of implementing AR&D on a spacecraft could be reduced from roughly $70M per mission to as low as $7M per mission, and the associated development time could be reduced from 4 years to 2 years, after the warehouse is completely developed. Table 1 shows the clear long-term benefits to the Agency in term of costs and schedules for various missions. (The methods used to arrive at the Table 1 numbers is presented in Appendices A and B.)

Krishnakumar, Kalmanje S.; Stillwater, Ryan A.; Babula, Maria; Moreau, Michael C.; Riedel, J. Ed; Mrozinski, Richard B.; Bradley, Arthur; Bryan, Thomas C.

2012-01-01

303

Growth Rate  

NSDL National Science Digital Library

This lesson from Illuminations uses growth charts for girls and boys to examine rates of change. The material uses slope to approximate the rate of change in height. Students will learn how to translate this data into a graph. The lesson is appropriate for grades 9-12 and should require 1 class period to complete.

2011-01-14

304

Heart rate  

Microsoft Academic Search

Numerous studies have shown that high heart rate is prospectively related to the development of atherosclerosis and of cardiovascular events. This relationship has been observed in the general population, in elderly subjects, in hypertensive cohorts, and in patients with myocardial infarction or heart failure. There is still debate over whether the association between fast heart rate and cardiovascular mortality is

P. Palatini

2000-01-01

305

Bedrock Incision Rates Through A Knickpoint Reach  

NASA Astrophysics Data System (ADS)

Bedrock river incision is a fundamental process in landscape evolution, controlling, for example, the rate at which base-level fall is propagated through the drainage net and hence the rate of sediment flux from source areas to sedimentary basin ­rsinks'. Particular attention has been focused on the processes and erosion rates upstream and downstream of knickpoints. These key bedrock river landforms propagate headwards to transmit the ­rmessage­_ to the drainage net that base-level has fallen. Knickpoints may be sharply defined as waterfalls or cascades, which separate reaches controlled by different environmental settings. They may originate as a result of base-level changes, tectonic uplift, lithologic and structural controls, tributary sediment inputs or environmental changes. Information on changes in bed incision rates through a knickpoint reach provides insight into the role of knickpoints in landscape evolution. The River Etive, Scotland, has alternating alluvial and bedrock reaches and a stepped long profile caused by series of knickpoints. To investigate the controls over bedrock incision in this river, numerical simulations were performed using a process-based incision model. Physical modelling of the impact of bedload on abrasion has been used to verify the numerical simulations and cosmogenic nuclides have been used to estimate incision rates as a final test. To characterise and assess changes in incision rates through the knickpoint reach, five bedrock samples were collected for cosmogenic isotope analysis from above and below a knickpoint in the bed of the River Etive. The samples were taken from as close to the low flow water surface as practically possible and are overtopped even at moderate flows; it is therefore highly unlikely that they have ever been shielded by either peat or alluvial sediment. The sample sites have clearly been fluvially sculpted and are smooth and rounded; they are therefore highly appropriate for the analysis. Quartz was extracted from the samples and fully prepared, following standard procedures. In addition, the overall incision rates in the reach have been estimated using a bedrock incision model. The numerical model, in which incision is dominated by abrasion by saltating sediment particles, shows how interactions between sediment dynamics and hydraulic conditions determine the incision rates. Sensitivity analyses incorporating a wide range of model parameterisations confirmed that erosion rates in bedrock rivers are controlled by stream power, but changes in sediment discharge and size also play important roles in incision. The numerical simulation results are further tested through tumbling mill experiments. Topographic and sedimentological data from the River Etive are used to estimate the erosion rates in the knickpoint reach using the numerical model. The numerical simulations show that the spatial patterns of incision are changed as model parameters are changed. A conventional, diffusion style, model produced declining slopes at knickpoints, while the new model, which incorporates sediment dynamics, produced more complicated pattern of incision. The physical processes operating in knickpoint reaches determined the mode and rate of incision, and these physical processes change with location within the reach. For abrasion, changes in effective sediment flux as transport stage changes plays the critical role in determining incision rates. These conclusions will be evaluated using the cosmogenically derived incision rates.

Kim, J.; Hoey, T.; Bishop, P.; Fifield, K.; Levchenko, V.

2003-12-01

306

The First Joint Report of the General Thomas P. Stafford Task Force and the Academician Vladimir F. Utkin Advisory Expert Council on the Shuttle-Mir Rendezvous and Docking Missions  

NASA Technical Reports Server (NTRS)

In October 1992, the National Aeronautics and Space Administration (NASA) and the Russian Space Agency (RSA) formally agreed to conduct a fundamentally new program of human cooperation in space. The 'Shuttle-Mir Program' encompassed combined astronaut-cosmonaut activities on the Shuttle, Soyuz Test Module(TM), and Mir station spacecraft. At that time, NASA and RSA limited the project to: the STS-60 mission carrying the first Russian cosmonaut to fly on the U.S. Space Shuttle; the launch of the first U.S. astronaut on the Soyuz vehicle for a multi-month mission as a member of a Mir crew; and the change-out of the U.S.-Russian Mir crews with a Russian crew during a Shuttle rendezvous and docking mission with the Mir Station. The objectives of the Phase 1 Program are to provide the basis for the resolution of engineering and technical problems related to the implementation of the ISS and future U.S.-Russian cooperation in space. This, combined with test data generated during the course of the Shuttle flights to the Mir station and extended joint activities between U.S. astronauts and Russian cosmonauts aboard Mir, is expected to reduce the technical risks associated with the construction and operation of the ISS. Phase 1 will further enhance the ISS by combining space operations and joint space technology demonstrations. Phase 1 also provides early opportunities for extended U.S. scientific and research activities, prior to utilization of the ISS.

1996-01-01

307

Reactions & Rates  

NSDL National Science Digital Library

Explore what makes a reaction happen by colliding atoms and molecules. Design experiments with different reactions, concentrations, and temperatures. When are reactions reversible? What affects the rate of a reaction?

Simulations, Phet I.; Koch, Linda; Lemaster, Ron; Loeblein, Trish; Perkins, Kathy; Gratny, Mindy

2006-12-01

308

Transcontinental Rates  

E-print Network

, and the Southern Pacifio from New Orleans to Los Angeles San Francisoo and Portland. All of t hese roads have to oross the continental divide and long stretches of country that furnish little , if any, loca l traffic. Also they must compete on t hrough freight... of the shipper for a fe years previous to as ­ certain the exact amount of the shi pments , the freight pa.~d , the insurance and other risk s . The rates offered did not have to be as low as t h e water r ates but low enough so t hat t wi th . the other...

Danskin, Floyd Brown

1913-01-01

309

The Near-Earth Asteroid Rendezvous (NEAR) Mission, the Mars Surveyor 2001 (MS01) Mission, and the Planetary Instrument Definition and Development Program (PIDDP)  

NASA Technical Reports Server (NTRS)

The NEAR Mission was launched on February 17, 1996 for a three year cruise to the asteroid 433 Eros. During October, November, and December 1998 cruise measurements with the gamma-ray spectrometer were made at three different escape-window-width settings. These were done in order to understand how the count rate and peak width change as the window width settings change. Analysis of these spectra was completed using the latest version of the spectral analysis program, RobWin. Results as a function of energy were combined with the results from the Schlumberger-Doll Research experiments (described below). Laboratory measurements were needed to confirm efficiency calculations above 6 MeV and to understand the relationship between the full energy peak areas and the areas of the first and second escape peaks as a function of the escape peak widths. A week of measurements was made at Schlumberger-Doll Research using their 14-MeV pulsed neutron generator and large soil samples. Data were collected after adding iron and nickel to the sample to increase the emission of high-energy lines. Approximately 24 hours of data were accumulated at each of three escape peak window widths. These data were analyzed with RobWin. Combining results from the cruise measurements and the laboratory measurements indicated that both data sets had similar energy dependence and that this energy dependence was different from that obtained using standard Monte Carlo calculations. Alternate methods of simulating the response of the detector to changes in the escape window widths are being investigated.

1999-01-01

310

The gas production rate of periodic comet d'Arrest  

NASA Technical Reports Server (NTRS)

Comet P/d'Arrest is a potential target for a rendezvous mission to a short period comet. Its light curve is rather peculiar, the comet being active only after perihelion passage. One apparition out of two is easy to observe from the ground. The 1995 apparition of the comet will offer a unique opportunity to characterize the outgassing properties of its nucleus.

Festou, Michel C.; Feldman, Paul D.; Ahearn, Michael F.

1992-01-01

311

Near Earth Asteroid Rendezvous - A Pictorial Voyage  

NSDL National Science Digital Library

This site offers students an opportunity to participate in a pictorial voyage that follows the NEAR spacecraft from its inception through the cruise phase to asteroid 433 Eros. They will learn about the rationale for visiting an asteroid, the instruments and construction of the spacecraft, and follow its flyby of the asteroid Mathilde, swingby of Earth, and encounter with Eros.

312

Telerobotic rendezvous and docking vision system architecture  

NASA Technical Reports Server (NTRS)

This research program has successfully demonstrated a new target label architecture that allows a microcomputer to determine the position, orientation, and identity of an object. It contains a CAD-like database with specific geometric information about the object for approach, grasping, and docking maneuvers. Successful demonstrations were performed selecting and docking an ORU box with either of two ORU receptacles. Small, but significant differences were seen in the two camera types used in the program, and camera sensitive program elements have been identified. The software has been formatted into a new co-autonomy system which provides various levels of operator interaction and promises to allow effective application of telerobotic systems while code improvements are continuing.

Gravely, Ben; Myers, Donald; Moody, David

1992-01-01

313

75 FR 44794 - Rendezvous International v.  

Federal Register 2010, 2011, 2012, 2013

...released only upon presentation by Respondents of Original endorsed Negotiable Bills of Lading. The payment terms were on a CAD (Cash Against Documents) basis.'' Complainant alleges that the terms of the Bill of Lading were ``violated by...

2010-07-29

314

Optimizing the Earth-LISA ‘rendezvous  

NASA Astrophysics Data System (ADS)

We present a general survey of heliocentric LISA orbits, hoping that it might help in the exercise of rescoping the mission. We try to semi-analytically optimize the orbital parameters in order to minimize the disturbances coming from the Earth-LISA interaction. In a set of numerical simulations, we include non-autonomous perturbations and provide an estimate of Doppler shift and breathing as a function of the trailing angle.

De Marchi, Fabrizio; Pucacco, Giuseppe; Bassan, Massimo

2012-02-01

315

Rendezvous at The Voyages of a  

E-print Network

submarines Arctic Antarctic " #12;Data courtesy A Brierley, P Fernandes and M Brandon Depth(m) 0 50 100 Draught (m) Astrium Snow load, especially in the Antarctic, depresses the sea ice freeboard #12;Sea Ice: A microscope within Autosub Flow Cytometer Laser sizing Fluorescence Diatom chain (left) with flow cytometer

Griffiths, Gwyn

316

Discovery: Near-Earth Asteroid Rendezvous (NEAR)  

NASA Technical Reports Server (NTRS)

The work carried out under this grant consisted of two parallel studies aimed at defining candidate missions for the initiation of the Discovery Program being considered by NASA's Solar System Exploration Division. The main study considered a Discover-class mission to a Near Earth Asteroid (NEA); the companion study considered a small telescope in Earth-orbit dedicated to ultra violet studies of solar system bodies. The results of these studies are summarized in two reports which are attached (Appendix 1 and Appendix 2).

Veverka, Joseph

1992-01-01

317

Long range targeting for space based rendezvous  

NASA Technical Reports Server (NTRS)

The work performed under this grant supported the Dexterous Flight Experiment one STS-62 The project required developing hardware and software for automating a TRAC sensor on orbit. The hardware developed by for the flight has been documented through standard NASA channels since it has to pass safety, environmental, and other issues. The software has not been documented previously, therefore, this report provides a software manual for the TRAC code developed for the grant.

Everett, Louis J.; Redfield, R. C.

1995-01-01

318

Mars Researchers Rendezvous on Remote Arctic Island  

NASA Technical Reports Server (NTRS)

Devon Island is situated in an isolated part of Canada's Nunavut Territory, and is usually considered to be the largest uninhabited island in the world. However, each summer since 1999, researchers from NASA's Haughton-Mars Project and the Mars Society reside at this 'polar desert' location to study the geologic and environmental characteristics of a site which is considered to be an excellent 'Mars analog': a terrestrial location wherein specific conditions approximate environmental features reported on Mars. Base camps established amidst the rocks and rubble surrounding the Haughton impact crater enable researchers to conduct surveys designed to test the habitat, equipment and technology that may be deployed during a human mission to Mars. One of the many objectives of the project scientists is to understand the ice formations around the Haughton area, in the hopes that this might ultimately assist with the recognition of areas where ice can be found at shallow depth on Mars.

These images of Devon Island from NASA's Multi-angle Imaging SpectroRadiometer (MISR) instrument provide contrasting views of the spectral and angular reflectance 'signatures' of different surfaces within the region. The top panel is a natural color view created with data from the red, green and blue-bands of MISR's nadir (vertical-viewing) camera. The bottom panel is a false-color multiangular composite of the same area, utilizing red band data from MISR's 60-degree backward, nadir, and 60-degree forward-viewing cameras, displayed as red, green and blue, respectively. In this representation, colors highlight textural properties of elements within the scene, with blue tones indicating smooth surfaces (which preferentially forward scatter sunlight) and red hues indicating rougher surfaces (which preferentially backscatter). The angular reflectance 'signature' of low clouds causes them to appear purple, and this visualization provides a unique way of distinguishing clouds from snow and ice.

The data were captured on June 28, 2001, during the early part of the arctic summer, when sea ice becomes thinner and begins to move depending upon localized currents and winds. In winter the entire region is locked with several meters of nearly motionless sea ice, which acts as a thermodynamic barrier to the loss of heat from the comparatively warm ocean to the colder atmosphere. Summer melting of sea ice can be observed at the two large, dark regions of open water; one is present in the Jones Sound (near the top to the left of center), and another appears in the Wellington Channel (left-hand edge). A large crack caused by tidal heaving has broken the ice cover over the Parry Channel (lower right-hand corner). A substantial ice cap permanently occupies the easternmost third of the island (upper right). Surface features such as dendritic meltwater channels incised into the island's surface are apparent. The Haughton-Mars project site is located slightly to the left and above image center, in an area which appears with relatively little surface ice, near the island's inner 'elbow.'

The images were acquired during Terra orbit 8132 and cover an area of about 334 kilometers x 229 kilometers. They utilize data from blocks 27 to 31 within World Reference System-2 path 42.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

2002-01-01

319

Correlating field and laboratory rates of particle abrasion, Rio Medio, Sangre de Cristo Mountains, New Mexico  

NASA Astrophysics Data System (ADS)

River bed sediments commonly fine downstream due to a combination of particle abrasion, selective transport of finer grains, and fining of the local sediment supply from hillslopes and tributaries. Particle abrasion rates can be directly measured in the laboratory using tumbling barrels and annular flumes, however, scaling experimental particle abrasion rates to the field has proven difficult due to the confounding effects of selective transport and local supply variations. Here we attempt to correlate laboratory and field rates of particle abrasion in a field setting where these confounding effects can be controlled. The Rio Medio, which flows westward from the crest of the Sangre de Cristo Mountains in north central New Mexico, is one of several streams studied by John P. Miller in the early 1960's. Several kilometers downstream of its headwaters, the river crosses the Picuris-Pecos fault. Upstream of the fault the river receives quartzite, sandstone and shale clasts from the Ortega Formation, while downstream sediments are supplied by the Embudo Granite. Because the upstream lithologies are not resupplied downstream of the fault, any observed fining of these clasts should be due only to abrasion and selective transport. We hypothesize that we can account for the effects of selective transport by comparing relative fining rates for the different upstream lithologies from both the field and a laboratory tumbler. By correlating laboratory abrasion rates with rock strength, we can predict the relative fining rates due solely to abrasion expected in the field; differences between the predicted and observed fining rates could then be attributed to selective transport. We used point counts to measure bed surface sediment grain size distributions at 15 locations along a 25 kilometer reach of the Rio Medio, beginning just downstream of the fault and ending upstream of a developed area with disturbed channel conditions. We recorded intermediate particle diameter as well as lithologic composition for 100 clasts at each location. To better characterize the size distribution of poorly represented lithologies we also measured every grain we could find of these minority lithologies within a one square meter area on adjacent bar top surfaces. At each sampling site we also measured channel gradient, and bank-full width and depth. We collected gravel samples for laboratory tumbling experiments and larger bedrock blocks from which we extracted cores for the Brazilian tensile splitting strength test. Preliminary results show very rapid fining of the weak sedimentary rocks downstream of the fault, much less rapid fining of the quartzite and a net downstream coarsening of the granitic sediments, which dominate the bed in the downstream end of the study reach. This enigmatic downstream coarsening may be a legacy of Pliestocene glaciation, which is evident in the landscape upstream of the fault. Outburst floods or debris flows from upstream moraines may have delivered large quantities of coarse sediments to downstream reaches, which are now relatively immobile. Despite these complications, the Rio Medio site may yet provide sufficient information to test our proposed method for scaling laboratory particle abrasion rates to the field.

Polito, P. J.; Sklar, L. S.

2006-12-01

320

Injury patterns and rates amongst students at the national institute of circus arts: an observational study.  

PubMed

Despite the ever-growing global participation in circus arts, very little research has been conducted into injuries associated with this physical discipline. To date, no studies have examined the incidence of injuries in circus training institutions and schools. In this study, data were collected over an academic year from all student injury presentations to the physiotherapy staff at one Australian circus school. A total of 351 injuries resulting in 1,948 treatments occurred in 33 female and 30 male circus students. The most common mechanisms of injury were acrobatics/tumbling (23%), handstands (12%), adagio (11%), and Chinese pole (10%). The most commonly injured body parts were the ankle (25%), lumbar spine (14%), and shoulder (12%). Interestingly, combined spinal injuries (cervical, thoracic, and lumbar) contributed to 35% of all initial injuries. Females sustained 71% of all hip injuries, but only 33% of all forearm injuries. Males accounted for 59% of all ankle injuries. There were no significant gender-based differences in other body areas. Results indicated that there is no gender-based difference in the overall rate of injury. However, females sustained significantly higher rates of hip injuries and males presented with more forearm and ankle injuries, perhaps reflecting the specific form and style of circus training and contortion undertaken. Spinal injuries had the highest overall rate of initial and follow-up presentations, indicating that both preventative and rehabilitative strategies could be addressed. It is suggested that the most common mechanisms of injury reflect both the amount of time spent training specific disciplines and the extreme physical difficulties and demands placed on the body. PMID:25433261

Munro, David

2014-12-01

321

On the relationship between visual magnitudes and gas and dust production rates in target comets to space missions  

NASA Astrophysics Data System (ADS)

In this paper, we report the results of a cometary research, developed during the last 10 years by us, involving a criterious analysis of gas and dust production rates in comets directly associated to recent space missions. For the determination of the water release rates we use the framework of the semi-empirical model of observed visual magnitudes [Newburn Jr., R.L. A semi-empirical photometric theory of cometary gas and dust production. Application to P/Halley's production rates, ESA-SP 174, 3, 1981; de Almeida, A.A., Singh, P.D., Huebner, W.F. Water release rates, active areas, and minimum nuclear radius derived from visual magnitudes of comets - an application to Comet 46P/Wirtanen, Planet. Space Sci. 45, 681-692, 1997; Sanzovo, G.C., de Almeida, A.A., Misra, A. et al. Mass-loss rates, dust particle sizes, nuclear active areas and minimum nuclear radii of target comets for missions STARDUST and CONTOUR, MNRAS 326, 852-868, 2001.], which once obtained, were directly converted into gas production rates. In turn, the dust release rates were obtained using the photometric model for dust particles [Newburn Jr., R.L., Spinrad, H. Spectrophotometry of seventeen comets. II - the continuum, AJ 90, 2591-2608, 1985; de Freitas Pacheco, J.A., Landaberry, S.J.C., Singh, P.D. Spectrophotometric observations of the Comet Halley during the 1985-86 apparition, MNRAS 235, 457-464, 1988; Sanzovo, G.C., Singh, P.D., Huebner, W.F. Dust colors, dust release rates, and dust-to-gas ratios in the comae of six comets, A&AS 120, 301-311, 1996.]. We applied these models to seven target comets, chosen for space missions of "fly-by"/impact and rendezvous/landing.

de Almeida, A. A.; Sanzovo, G. C.; Singh, P. D.; Misra, A.; Miguel Torres, R.; Boice, D. C.; Huebner, W. F.

322

Take a Tumble: Weathering and Erosion Using a Rock Tumbler  

ERIC Educational Resources Information Center

Weathering--the physical and chemical breakdown of geologic materials--and erosion--the transport of materials by wind, water, or ice--can be subtle, yet powerful forces. For example, shale, a rock made of mud-sized particles, is by far the most common sedimentary rock, a testament to the ability of weathering and erosion to take a rock and reduce…

Coffey, Patrick; Mattox, Steve

2006-01-01

323

Run-and-tumble particles in speckle fields  

E-print Network

The random energy landscapes developed by speckle fields can be used to confine and manipulate a large number of micro-particles with a single laser beam. By means of molecular dynamics simulations, we investigate the static and dynamic properties of an active suspension of swimming bacteria embedded into speckle patterns. Looking at the correlation of the density fluctuations and the equilibrium density profiles, we observe a crossover phenomenon when the forces exerted by the speckles are equal to the bacteria's propulsion.

M. Paoluzzi; R. Di Leonardo; L. Angelani

2014-01-27

324

Failed Escape: Solid Surfaces Prevent Tumbling of Escherichia coli  

E-print Network

Understanding how bacteria move close to surfaces is crucial for a broad range of microbial processes including biofilm formation, bacterial dispersion, and pathogenic infections. We used digital holographic microscopy to ...

Molaei, Mehdi

325

Reentry survival analysis of tumbling metallic hollow cylinder  

NASA Astrophysics Data System (ADS)

The survival of orbital debris reentering the Earth's atmosphere is considered. The numerical approach of NASA's Object Reentry Survival Analysis Tool (ORSAT) is reviewed, and a new equation accounting for reradiation heat loss of hollow cylindrical objects is presented. Based on these, a code called Survivability Analysis Program for Atmospheric Reentry (SAPAR) has been developed, and the new equation for reradiation heat loss is validated. Using this equation in conjunction with the formulation used in ORSAT, a comparative case study on the Delta-II second stage cylindrical tank is given, demonstrating that the analysis using the proposed equation is in good agreement with the actual recovered object when a practical value for thermal emissivity is used. A detailed explanation of the revised formulation is given, and additional simulation results are presented. Finally, discussions are made to address the applicability of the proposed equation to be incorporated in future survival analyses of orbital debris.

Sim, Hyung-seok; Kim, Kyu-hong

2011-09-01

326

Tumbling down a different pathway to genetic instability  

PubMed Central

Ulcerative colitis (UC), a chronic inflammatory condition associated with a predisposition to colon cancer, is frequently characterized by DNA damage in the form of microsatellite instability (MSI). A new report links inflammation in UC with increases in the DNA repair enzymes 3-methyladenine DNA glycosylase and apurinic/apyrimidinic endonuclease, and, paradoxically, with increased MSI. These findings may represent a novel mechanism contributing to MSI in chronic inflammation. PMID:14679175

Guo, Haiwei H.; Loeb, Lawrence A.

2003-01-01

327

Vesicle tumbling inhibited by inertia Aymen Laadhari,1  

E-print Network

constitute a model system for the study of red blood cells (RBCs) dynamics and blood rheology. In the blood numbers: 87.16.D- 83.50.Ha 87.17.Jj 83.80.Lz 87.19.rh I. INTRODUCTION The study of models of red blood elasticity)3 . The inextensible character has proven to confer to vesicles rich dynamics3 , since

Paris-Sud XI, Université de

328

Total Fertility Rate  

NSDL National Science Digital Library

Chart of fertility rates by country showing the very high fertility rates in the least developed countries and the very low fertility rates in the most developed countries as of 2008 according to the CIA world factbook. To maintain stable population, fertility rates must be slightly above 2.

329

GENERAL TUITION RATES UNDERGRADUATES  

E-print Network

GENERAL TUITION RATES UNDERGRADUATES The following per-credit semester tuition rates do not vary a flat tuition rate based on a minimum 13-credit load (including audited classes) and pay the student services fee, as well as a full technology/collegiate fee. Credits 1­12 are assessed at the per-credit rate

Amin, S. Massoud

330

Rating Movies and Rating the Raters Who Rate Them.  

PubMed

The movie distribution company Netflix has generated considerable buzz in the statistics community by offering a million dollar prize for improvements to its movie rating system. Among the statisticians and computer scientists who have disclosed their techniques, the emphasis has been on machine learning approaches. This article has the modest goal of discussing a simple model for movie rating and other forms of democratic rating. Because the model involves a large number of parameters, it is nontrivial to carry out maximum likelihood estimation. Here we derive a straightforward EM algorithm from the perspective of the more general MM algorithm. The algorithm is capable of finding the global maximum on a likelihood landscape littered with inferior modes. We apply two variants of the model to a dataset from the MovieLens archive and compare their results. Our model identifies quirky raters, redefines the raw rankings, and permits imputation of missing ratings. The model is intended to stimulate discussion and development of better theory rather than to win the prize. It has the added benefit of introducing readers to some of the issues connected with analyzing high-dimensional data. PMID:20802818

Zhou, Hua; Lange, Kenneth

2009-11-01

331

Rating Movies and Rating the Raters Who Rate Them  

PubMed Central

The movie distribution company Netflix has generated considerable buzz in the statistics community by offering a million dollar prize for improvements to its movie rating system. Among the statisticians and computer scientists who have disclosed their techniques, the emphasis has been on machine learning approaches. This article has the modest goal of discussing a simple model for movie rating and other forms of democratic rating. Because the model involves a large number of parameters, it is nontrivial to carry out maximum likelihood estimation. Here we derive a straightforward EM algorithm from the perspective of the more general MM algorithm. The algorithm is capable of finding the global maximum on a likelihood landscape littered with inferior modes. We apply two variants of the model to a dataset from the MovieLens archive and compare their results. Our model identifies quirky raters, redefines the raw rankings, and permits imputation of missing ratings. The model is intended to stimulate discussion and development of better theory rather than to win the prize. It has the added benefit of introducing readers to some of the issues connected with analyzing high-dimensional data. PMID:20802818

Zhou, Hua; Lange, Kenneth

2010-01-01

332

Rating the ratings: How good are commercial governance ratings?  

Microsoft Academic Search

Proxy advisory and corporate governance rating firms (such as RiskMetrics\\/Institutional Shareholder Services, GovernanceMetrics International, and The Corporate Library) play an increasingly important role in U.S. public markets. They rank the quality of firm corporate governance, advise shareholders how to vote, and sometimes press for governance changes. We examine whether commercially available corporate governance rankings provide useful information for shareholders. Our

Robert M. Daines; Ian D. Gow; David F. Larcker

2010-01-01

333

Target Heart Rate Calculator  

MedlinePLUS

... My Saved Articles » My ACS » + - Text Size Target Heart Rate Calculator Compute your best workout Enter your age ... is your age? years. How to Check Your Heart Rate Right after you stop exercising, take your pulse: ...

334

Calculating Divorce Rates  

NSDL National Science Digital Library

This exercise from a course in family sociology asseses students' ability to interpret divorce rates from provided spreadsheet data and to critically analyze three articles that use divorce rates in their content.

Carroll, Joseph

335

Heart Rate and Exercise  

NSDL National Science Digital Library

In this activity about heart health (on page 27 of the PDF), learners measure their heart rates after a variety of physical activities and compare the results with their resting heart rates, and with the heart rates of other learners in their groups. Learners also make predictions about their pulse rates. This lesson guide includes background information, setup and management tips, extension ideas, information about the heart in space and a handout.

Tharp, Barbara Z.; Erdmann, Deanne B.; Matyas, Marsha L.; Mcneel, Ronald L.; Moreno, Nancy P.

2009-01-01

336

Exchange rate exposure  

Microsoft Academic Search

In this paper we examine the relationship between exchange rate movements and firm value. We estimate the exchange rate exposure of publicly listed firms in a sample of eight (non-US) industrialized and emerging markets. We find that exchange rate movements do matter for a significant fraction of firms, though which firms are affected and the direction of exposure depends on

Kathryn M. E. Dominguez; Linda L. Tesar

2006-01-01

337

Exchange-Rate Regimes: \\  

Microsoft Academic Search

Traditionally the IMF's Annual Report on Exchange Arrangements and Exchange Restrictions has been the main source of information about the exchange-rate policies pursued by member countries. The classification contained therein has been used to document the evolution of exchange rate regimes over time as well as to study the relationship between economic performance and the choice of exchange rate system.

Hans Genberg; Alexander K. Swoboda

2004-01-01

338

The Japanese Saving Rate  

Microsoft Academic Search

Despite much work, economists have not been able to quantitatively account for the differences in the Japanese and U.S. saving rates after World War II. In this paper, we show that the use of actual Japanese total factor productivity growth rates in a standard growth model generates saving rates that are reasonably similar to the Japanese data between 1956 and

Kaiji Chen; Ay?e ?mrohoro?lu; Selahattin ?mrohoro?lu

2006-01-01

339

POVERTY EQUIVALENT GROWTH RATE  

Microsoft Academic Search

This paper proposes a new type of growth rate, called the “poverty equivalent growth rate” (PEGR), which takes into account both the growth rate in mean income and how the benefits of growth are distributed between the poor and the non-poor. The proposed measure satisfies a basic requirement that the proportional reduction in poverty is a monotonically increasing function of

N anak K akwani; H yun H. S on

2008-01-01

340

RateNet  

NSDL National Science Digital Library

RateNet was jointly developed by DataTrac, PR Newswire (discussed in the February 7, 1997 Scout Report) and IDC Financial Publishing. RateNet connects consumers to financial institutions on the Internet by providing a ranking service for the banking industry. Users may examine the current and historic interest rates of over 11,000 financial institutions from 175 markets across America. There are also 116 RateNet indices which monitor the deposit and lending rates for 776 of the largest institutions.

1998-01-01

341

Rate theories for biologists  

PubMed Central

Some of the rate theories that are most useful for modeling biological processes are reviewed. By delving into some of the details and subtleties in the development of the theories, the review will hopefully help the reader gain a more than superficial perspective. Examples are presented to illustrate how rate theories can be used to generate insight at the microscopic level into biomolecular behaviors. Attempt is made to clear up a number of misconceptions in the literature regarding popular rate theories, including the appearance of Planck’s constant in the transition-state theory and the Smoluchowski result as an upper limit for protein-protein and protein-DNA association rate constants. Future work in combining the implementation of rate theories through computer simulations with experimental probes of rate processes, and in modeling effects of intracellular environments so theories can be used for generating rate constants for systems biology studies is particularly exciting. PMID:20691138

Zhou, Huan-Xiang

2012-01-01

342

76 FR 38717 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This [[Page...

2011-07-01

343

Observed Barium Emission Rates  

NASA Technical Reports Server (NTRS)

The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

1993-01-01

344

Credit Rating Targets  

Microsoft Academic Search

Credit ratings can be viewed as a summary statistic that captures various elements of a firm's capital structure. They incorporate a firm's debt ratio, the maturity and priority structure of its debt, as well as the volatility of its cash flows. However, regressions of credit ratings on firm characteristics provide inferences that are not always consistent with the interpretations of

Armen Hovakimian; Ayla Kayhan; Sheridan Titman

345

Student Ratings of Instruction  

ERIC Educational Resources Information Center

Research on student assessment of teachers is reviewed to answer the questions: What discriminations do students make? Are ratings a function of a course or of a teacher? Which teacher and course characteristics are most important? Do ratings reflect the amount learned? Do teachers profit from feedback? (Author/JH)

Kulik, James A.; Kulik, Chen-Lin C.

1974-01-01

346

Mortality Rate, Under-5  

NSDL National Science Digital Library

Under five mortality data for nearly all countries in the world from 2005-2008. A broader measure of child health than infant mortality, this is the probability of dying before ones fifth birthday given the current rates. Rates in countries vary widely from the world average of 67-per-1000 which is decreasing.

Bank, World

347

Metabolic rate measurement system  

NASA Technical Reports Server (NTRS)

The Metabolic Rate Measurement System (MRMS) is an uncomplicated and accurate apparatus for measuring oxygen consumption and carbon dioxide production of a test subject. From this one can determine the subject's metabolic rate for a variety of conditions, such as resting or light exercise. MRMS utilizes an LSI/11-03 microcomputer to monitor and control the experimental apparatus.

Koester, K.; Crosier, W.

1980-01-01

348

Interest rates mapping  

NASA Astrophysics Data System (ADS)

The present study deals with the analysis and mapping of Swiss franc interest rates. Interest rates depend on time and maturity, defining term structure of the interest rate curves (IRC). In the present study IRC are considered in a two-dimensional feature space-time and maturity. Exploratory data analysis includes a variety of tools widely used in econophysics and geostatistics. Geostatistical models and machine learning algorithms (multilayer perceptron and Support Vector Machines) were applied to produce interest rate maps. IR maps can be used for the visualisation and pattern perception purposes, to develop and to explore economical hypotheses, to produce dynamic asset-liability simulations and for financial risk assessments. The feasibility of an application of interest rates mapping approach for the IRC forecasting is considered as well.

Kanevski, M.; Maignan, M.; Pozdnoukhov, A.; Timonin, V.

2008-06-01

349

77 FR 76586 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2012-12-28

350

76 FR 77581 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2011-12-13

351

78 FR 39434 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2013-07-01

352

75 FR 37872 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2010-06-30

353

75 FR 17453 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

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2010-04-06

354

78 FR 62932 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2013-10-22

355

75 FR 81326 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2010-12-27

356

77 FR 20476 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2012-04-04

357

76 FR 18821 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

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2011-04-05

358

77 FR 39560 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2012-07-03

359

77 FR 59447 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2012-09-27

360

78 FR 18664 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2013-03-27

361

75 FR 60152 - Interest Rates  

Federal Register 2010, 2011, 2012, 2013

...SMALL BUSINESS ADMINISTRATION Interest Rates The Small Business Administration publishes an interest rate called the optional ``peg...rate for guaranteed fluctuating interest rate SBA loans. This rate will...

2010-09-29

362

Viral Mutation Rates ?  

PubMed Central

Accurate estimates of virus mutation rates are important to understand the evolution of the viruses and to combat them. However, methods of estimation are varied and often complex. Here, we critically review over 40 original studies and establish criteria to facilitate comparative analyses. The mutation rates of 23 viruses are presented as substitutions per nucleotide per cell infection (s/n/c) and corrected for selection bias where necessary, using a new statistical method. The resulting rates range from 10?8 to10?6 s/n/c for DNA viruses and from 10?6 to 10?4 s/n/c for RNA viruses. Similar to what has been shown previously for DNA viruses, there appears to be a negative correlation between mutation rate and genome size among RNA viruses, but this result requires further experimental testing. Contrary to some suggestions, the mutation rate of retroviruses is not lower than that of other RNA viruses. We also show that nucleotide substitutions are on average four times more common than insertions/deletions (indels). Finally, we provide estimates of the mutation rate per nucleotide per strand copying, which tends to be lower than that per cell infection because some viruses undergo several rounds of copying per cell, particularly double-stranded DNA viruses. A regularly updated virus mutation rate data set will be available at www.uv.es/rsanjuan/virmut. PMID:20660197

Sanjuán, Rafael; Nebot, Miguel R.; Chirico, Nicola; Mansky, Louis M.; Belshaw, Robert

2010-01-01

363

Rating the Risks.  

ERIC Educational Resources Information Center

Explains how people arrive at personal hazard assessments. Explores why people overestimate some hazards and underestimate others. Examines risk ratings for activities and technologies such as nuclear power, motor vehicles, pesticides, and vaccinations. (MA)

Slovic, Paul; And Others

1979-01-01

364

Rating Your Cash Manager?  

ERIC Educational Resources Information Center

The primary objective of a public cash management policy should include safety, liquidity, yield, and legality. Contains a cash management policy/procedure checklist, a test for cash managers, and a formula for calculating the rate of return. (MLF)

Nielsen, George A.; Johannisson, Eric E.

1989-01-01

365

Burning Rate Emulator  

NASA Video Gallery

The Burning Rate Emulator is a gas fuel investigation attempting to emulate the burning of solids to improve our understanding of materials''flammability over a wide range of conditions. The approa...

366

Heart Rate Monitor  

NASA Technical Reports Server (NTRS)

In the mid 70's, NASA saw a need for a long term electrocardiographic electrode suitable for use on astronauts. Heart Rate Inc.'s insulated capacitive electrode is constructed of thin dielectric film applied to stainless steel surface, originally developed under a grant by Texas Technical University. HRI, Inc. was awarded NASA license and continued development of heart rate monitor for use on exercise machines for physical fitness and medical markets.

1984-01-01

367

Rate Tornado Damage  

NSDL National Science Digital Library

An interactive Flash animation that educates students about the Fujita scale for rating tornado wind speeds and the damage caused by tornados. After being presented with photographs of tornado damage, students are challenged to assign the tornado a rating on the F-scale. The interactive explains the different levels of the F-scale and provides instant feedback on whether or not the correct category was assigned to the tornado.

Krock, Lexi; Pbs

368

High population increase rates.  

PubMed

In addition to its economic and ethnic difficulties, the USSR faces several pressing demographic problems, including high population increase rates in several of its constituent republics. It has now become clear that although the country's rigid centralized planning succeeded in covering the basic needs of people, it did not lead to welfare growth. Since the 1970s, the Soviet economy has remained sluggish, which as led to increase in the death and birth rates. Furthermore, the ideology that held that demography could be entirely controlled by the country's political and economic system is contradicted by current Soviet reality, which shows that religion and ethnicity also play a significant role in demographic dynamics. Currently, Soviet republics fall under 2 categories--areas with high or low natural population increase rates. Republics with low rates consist of Christian populations (Armenia, Moldavia, Georgia, Byelorussia, Russia, Lithuania, Estonia, Latvia, Ukraine), while republics with high rates are Muslim (Tadzhikistan, Uzbekistan, Turkmenistan, Kirgizia, Azerbaijan Kazakhstan). The later group has natural increase rates as high as 3.3%. Although the USSR as a whole is not considered a developing country, the later group of republics fit the description of the UNFPA's priority list. Another serious demographic issue facing the USSR is its extremely high rate of abortion. This is especially true in the republics of low birth rates, where up to 60% of all pregnancies are terminated by induced abortions. Up to 1/5 of the USSR's annual health care budget is spent on clinical abortions -- money which could be better spent on the production of contraceptives. Along with the recent political and economic changes, the USSR is now eager to deal with its demographic problems. PMID:12284289

1991-09-01

369

Rates of spontaneous mutation.  

PubMed Central

Rates of spontaneous mutation per genome as measured in the laboratory are remarkably similar within broad groups of organisms but differ strikingly among groups. Mutation rates in RNA viruses, whose genomes contain ca. 10(4) bases, are roughly 1 per genome per replication for lytic viruses and roughly 0.1 per genome per replication for retroviruses and a retrotransposon. Mutation rates in microbes with DNA-based chromosomes are close to 1/300 per genome per replication; in this group, therefore, rates per base pair vary inversely and hugely as genome sizes vary from 6 x 10(3) to 4 x 10(7) bases or base pairs. Mutation rates in higher eukaryotes are roughly 0.1-100 per genome per sexual generation but are currently indistinguishable from 1/300 per cell division per effective genome (which excludes the fraction of the genome in which most mutations are neutral). It is now possible to specify some of the evolutionary forces that shape these diverse mutation rates. PMID:9560386

Drake, J W; Charlesworth, B; Charlesworth, D; Crow, J F

1998-01-01

370

Heart Rate Monitors  

NASA Technical Reports Server (NTRS)

Under a NASA grant, Dr. Robert M. Davis and Dr. William M. Portnoy came up with a new type of electrocardiographic electrode that would enable long term use on astronauts. Their invention was an insulated capacitive electrode constructed of a thin dielectric film. NASA subsequently licensed the electrode technology to Richard Charnitski, inventor of the VersaClimber, who founded Heart Rate, Inc., to further develop and manufacture personal heart monitors and to produce exercise machines using the technology for the physical fitness, medical and home markets. Same technology is on both the Home and Institutional Model VersaClimbers. On the Home Model an infrared heart beat transmitter is worn under exercise clothing. Transmitted heart rate is used to control the work intensity on the VersaClimber using the heart rate as the speedometer of the exercise. This offers advantages to a full range of users from the cardiac rehab patient to the high level physical conditioning of elite athletes. The company manufactures and markets five models of the 1*2*3 HEART RATE monitors that are used wherever people exercise to accurately monitor their heart rate. Company is developing a talking heart rate monitor that works with portable headset radios. A version of the heart beat transmitter will be available to the manufacturers of other aerobic exercise machines.

1990-01-01

371

Cooling Rates of Chondrules  

NASA Astrophysics Data System (ADS)

Cooling rates for chondrules are among many aspects of chondrule forming events currently under debate and estimates by different authors vary considerably. Calculations based on radiation from isolated chondrules yield an extremely high cooling rate of ~10^5 degrees C/hr [1]. The cooling rates derived from previous petrological and experimental studies are much lower but inconsistent, ranging from 5 - 100 degrees C/hr [2] to ~1000 degrees C/hr [3]. Since cooling rates bear important information about the chondrule-forming environment, they need to be more tightly constrained. Here we re-evaluate the chondrule cooling rates based on the results of our recent flash heating experiments, mainly the volatile loss data, as well as textures, and olivine zoning profiles of the chondrule analog materials. Linear cooling vs. cooling curves. Many previous studies either assumed or used linear cooling rates for chondrules [2,3]. In reality, even with simple radiative cooling, the cooling rates should have followed a non-linear path, according to the Stefan- Boltzmann law. We used non-linear cooling rates throughout our experiments, and our observations show that the initial cooling rate at the high temperature end of a specific cooling curve affects chondrule properties most. Volatile loss results. Our Na and S loss experiments [4] have shown that to reproduce the very high Na contents [5,6] and primary sulfide [7] found in some natural chondrules, heating has to be brief, but fast cooling and relatively high fO2 are also essential. With an fO2 of ~10^(-10) atm, for a type II chondrule flash heated to its liquidus temperature, cooling curves beginning at ~2500 degrees C/hr are necessary to retain >90% of its original Na content or part of its S, unless the ambient gas is very enriched in these elements [8]. Under lower fO2, or for type I chondrule composition, even higher cooling rates are required. Textures and olivine zoning with ~10^1 - ~10^3 degrees C/hr initial cooling rates. Depending on temperature and starting composition, the charges cooled under such cooling rates exhibit either total glass, BO, PO, POP, or relict olivine texture, consistent with previous linear cooling experiments [2,3,9]. For type IIAB chondrule charges with PO, olivine zoning produced by initially cooling between 500 degrees C/hr and 5000 degrees C/hr is very similar to that of Semarkona chondrules [2]. In this cooling rate range, higher cooling rates enhance the zoning. Charges cooled between 10 degrees C/hr and 100 degrees C/hr show very limited olivine zoning. Textures and olivine zoning with ~10^5 degrees C/hr initial cooling rates. A cooling rate this high can only be achieved by quenching the charge in air immediately after the desired temperature is reached. The final charges are composed of glass and numerous small olivine crystals with grain sizes seldom exceeding 20 fm. Repeated heating/quenching cycles at lower temperature slowly coarsen the olivine crystals: 100 heating/quenching cycles can double the size of olivine, but the final olivine crystals are somewhat rounded and have curved embayments. Very limited olivine zoning is produced: the core/rim difference in FeO rarely exceeds 5%. Discussion. Under flash heating conditions, cooling rates of 10 - 100 degrees C/hr will cause extensive volatile loss except with an unusual ambient gas, and produce limited olivine zoning. Cooling rates of as high as 105 degrees C/hr certainly can preserve high volatile contents, but the crystals grown are too small. Repeated heating/extremely fast cooling cycles can coarsen the olivine grains, but not enough, and do not reproduce porphyritic chondrule textures well. In addition, the heating mechanism to heat chondrules hundreds of times with peak temperatures always constrained within a narrow window is unrealistic. The initial cooling rates of the chondrule cooling curves are more likely between these two extremes, and from our volatile loss results, they are probably in the range of several thousand degrees per hour, especially for type II chondrules.

Yu, Y.; Hewins, R. H.; Eiben, B. A.

1995-09-01

372

Optical rate sensor algorithms  

NASA Technical Reports Server (NTRS)

Optical sensors, in particular Charge Coupled Device (CCD) arrays, will be used on Space Station to track stars in order to provide inertial attitude reference. Algorithms are presented to derive attitude rate from the optical sensors. The first algorithm is a recursive differentiator. A variance reduction factor (VRF) of 0.0228 was achieved with a rise time of 10 samples. A VRF of 0.2522 gives a rise time of 4 samples. The second algorithm is based on the direct manipulation of the pixel intensity outputs of the sensor. In 1-dimensional simulations, the derived rate was with 0.07 percent of the actual rate in the presence of additive Gaussian noise with a signal to noise ratio of 60 dB.

Uhde-Lacovara, Jo A.

1989-01-01

373

Time rate collision matrix  

SciTech Connect

The collision integral terms in Boltzmann equation are reformulated numerically leading to the substitution of the multiple integrals with a multiplicative matrix of the two colliding species velocity distribution functions which varies with the differential collision cross section. A matrix of lower rank may be constructed when one of the distribution functions is specified, in which case the matrix elements represent kinetic transition probabilities in the velocity space and the multiplication of the time rate collision matrix with the unknown velocity distribution function expresses the time rate of change of the distribution. The collision matrix may be used to describe the time evolution of systems in nonequilibrium conditions, to evaluate the rate of momentum and energy transfer between given species, or to generate validity criteria for linearized kinetic equations.

Stoenescu, M.L.; Smith, T.M.

1980-02-01

374

Federal Reserve Rate Cuts  

NSDL National Science Digital Library

This week's In the News chronicles recent Federal Reserve Board decisions to lower interest rates. The eleven resources discussed provide news, opinion, and consumer information on the FRB BOG action. Following the first US interest rate cut in three years on September 29, 1998, FED Chairman Alan Greenspan caught fire from Wall Street. "Traders were disappointed" in the mere quarter point drop, according to Time business reporter Bernard Baumohl, but "Greenspan will have to make do with the gratitude of the rest of the world." Although the DOW initially fell 54 points Tuesday, a second 0.25% cut to short-term interest rates on October 15, 1998 sent stocks soaring 330 points--the third largest one-day point gain in history. Analysts now hope that US investor optimism--coupled with IMF and World Bank action in Brazil, Russia, and Asia--will ease the world-wide economic crises.

Waters, Megan.

1998-01-01

375

A finite-rate chemistry model for using in-situ gas composition measurements within a cometary diamagnetic cavity as a remote sensing tool for studying volatile materials on the nucleus surface  

NASA Astrophysics Data System (ADS)

If everything goes according to plan, Rosetta will rendez-vous with comet 67P/Churyumov-Gerasimenko in May 2014 and will, among other objectives, study the physicochemical evolution of the cometary coma from onset of activity at large solar distances through perihelion at 1.2 AU. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) allows the determination of both neutrals and positive ions in the coma. In situ gas density and composition measurements within the diamagnetic cavity at a certain distance from the nucleus can be used to obtain estimates of particle densities throughout the cavity, as well as give an estimate of the outgassing rates and volatile material composition at the nucleus surface. This is an inverse problem that has been implemented using a finite-rate chemistry model. It requires knowledge of the solar UV flux, the outgassing flow field, and the chemical reactions that transform the neutral gas as it expands outward (e.g. photo-ionization). In this way, in situ measurements in the coma can be used as a remote sensing tool for studying nucleus surface composition. This will be compared to the "ground truth" provided by the instruments on the Philae lander. This contribution will explain the finite-rate chemistry model used and illustrate the data inversion technique. Attention is paid to the opportunities and limitations of the proposed technique.

Dhooghe, Frederik; De Keyser, Johan; Gunnel, Herbert; Maggiolo, Romain

2014-05-01

376

Stocking Rate Decisions  

E-print Network

Stocking Rate Decisions Key to Successful Ranch Management Larry D. White and AlIan McGinty Extension Range Specialists, The Texas A&M University System On any ranch, decisions must be made as to the management of each ranch resource (land, animals... Stocking Rate Decisions Key to Successful Ranch Management Larry D. White and AlIan McGinty Extension Range Specialists, The Texas A&M University System On any ranch, decisions must be made as to the management of each ranch resource (land, animals...

White, Larry D.; McGinty, Allan

1999-02-15

377

Currency Exchange Rates.  

ERIC Educational Resources Information Center

This curriculum unit of the Muncie (Indiana) Southside High School is to simulate the dynamics of foreign currency exchange rates from the perspectives of: (1) a major U.S. corporation, ABB Power T & D Company, Inc., of Muncie, Indiana, a manufacturer of large power transformers for the domestic and foreign markets; and (2) individual consumers…

Siler, Carl R.

378

Estimating Rates of Photosynthesis  

NSDL National Science Digital Library

In this lab activity from the Biotechnology Alliance for Suncoast Biology Educators, students will explore photosynthesis, develop a testable hypothesis about the effect of light quality (color) on the rate of photosynthesis of Elodea, and graph measurement data from their testing. The lesson includes background information on photosynthesis, the materials needed, and the procedure.

Keirle, Matt

2012-06-28

379

Optical rate sensor algorithms  

Microsoft Academic Search

Optical sensors, in particular Charge Coupled Device (CCD) arrays, will be used on Space Station to track stars in order to provide inertial attitude reference. Algorithms are presented to derive attitude rate from the optical sensors. The first algorithm is a recursive differentiator. A variance reduction factor (VRF) of 0.0228 was achieved with a rise time of 10 samples. A

Jo A. Uhde-Lacovara

1989-01-01

380

China's exchange rate policy  

Microsoft Academic Search

Should or will the yuan depreciate? This is an important question widely speculated in world financial markets and intensively debated in China in the wake of the East Asian financial crisis in 1997. The present paper examines in detail the fundamentals that determine the exchange rate in China and concludes with two important findings. One is that the past two

Yingfeng Xu

2000-01-01

381

What's in a Rating?  

ERIC Educational Resources Information Center

We examine the relationship between the formal ratings that principals give teachers and a variety of observable teacher characteristics, including proxies for productivity. Prior work has shown that principals can differentiate between more and less effective teachers, especially at the tails of the quality distribution, and that subjective…

Jacob, Brian A.; Walsh, Elias

2011-01-01

382

How Do You Rate?  

ERIC Educational Resources Information Center

An attempt was made at Mountain Empire Community College to develop and implement an impartial and equitable method of faculty evaluation. As part of this process, an instrument was developed to provide both a quantitative and qualitative student rating of faculty. The instrument contains 10 questions covering the syllabus/course outline,…

Kocher, Earl D.; Houston, Charles

383

Average Rate of Change  

NSDL National Science Digital Library

This demo provides students with a concrete understanding of the average rate of change for physical situations and for functions described in tabular or graphic form. Animations in gif and Quicktime format are available, as well as Excel programs for classroom or student use.

Roberts, Lila F.; Hill, David R.

2005-04-21

384

Unusual ISS Rate Signature  

NASA Technical Reports Server (NTRS)

On November 23, 2011 International Space Station Guidance, Navigation, and Control reported unusual pitch rate disturbance. These disturbances were an order of magnitude greater than nominal rates. The Loads and Dynamics team was asked to review and analyze current accelerometer data to investigate this disturbance. This paper will cover the investigation process under taken by the Loads and Dynamics group. It will detail the accelerometers used and analysis performed. The analysis included performing Frequency Fourier Transform of the data to identify the mode of interest. This frequency data is then reviewed with modal analysis of the ISS system model. Once this analysis is complete and the disturbance quantified, a forcing function was produced to replicate the disturbance. This allows the Loads and Dynamics team to report the load limit values for the 100's of interfaces on the ISS.

Laible, Michael R.

2011-01-01

385

Rate Tornado Damage  

NSDL National Science Digital Library

Tornadoes can produce damage that ranges from broken tree limbs to a block of houses swept from their foundations. They can inflict utter devastation across a wide swath of land or, destroy one house and leave others on either side largely untouched. In this interactive feature from NOVA Online, sudents examine a series of photos of tornado damage and assign intensity ratings (on the Fulita scale) based on what they see.

2011-02-24

386

Exchange Rate Economics  

Microsoft Academic Search

The paper summarizes the current theory of how a floating exchange rate is determined, dividing the subject into what determines\\u000a the steady state and what determines the transition to steady state. The inadequacies of this model are examined, and an alternative\\u000a “behavioral” model, which recognizes that the foreign exchange market is populated by both fundamentalists and chartists is\\u000a presented. It

John Williamson

2009-01-01

387

Composite rating scales.  

PubMed

Rating scales are instruments that are very frequently used by clinicians to perform patient assessments. Typically, rating scales grade the attribute on an ordinal level of measurement, i.e., a rank ordering, meaning that the numbers assigned to the different ranks (item scores) do not represent 'real numbers' or 'physical magnitudes'. Single-item scales have some advantages, such as simplicity and low respondent burden, but they may also suffer from disadvantages, such as ambiguous score meanings and low responsiveness. Multi-item scales, in contrast, seem more adequate for assessment of complex constructs, allowing for detailed evaluation. Total scores representing the value of the construct may be quite precise and thus the responsiveness of the scale may be high. The most common strategy for obtaining the total score is the sum of the item scores, a strategy that constitutes one of the most important problems with these types of scales. A summative score of ordinal figures is not a 'real magnitude' and may have little sense. This paper is a review of the theoretical frameworks of the main theories used to develop rating scales (Classical Test Theory and Item Response Theory). Bearing in mind that no alternative is perfect, additional research in this field and judicious decisions are called for. PMID:19732911

Martinez-Martin, Pablo

2010-02-15

388

Martian atmospheric erosion rates.  

PubMed

Mars was once wet but is now dry, and the fate of its ancient carbon dioxide atmosphere is one of the biggest puzzles in martian planetology. We have measured the current loss rate due to the solar wind interaction for different species: Q(O+) = 1.6.10(23) per second = 4 grams per second (g s(-1)), Q(O+2) = 1.5.10(23) s(-1) = 8 g s(-1), and Q(CO+2) = 8.10(22) s(-1) = 6 g s(-1) in the energy range of 30 to 30,000 electron volts per charge. These rates can be propagated backward over a period of 3.5 billion years, resulting in the total removal of 0.2 to 4 millibar of carbon dioxide and a few centimeters of water. The escape rate is low, and thus one has to continue searching for water reservoirs and carbon dioxide stores on or beneath the planetary surface and investigate other escape channels. PMID:17255508

Barabash, Stas; Fedorov, Andrei; Lundin, Rickard; Sauvaud, Jean-Andre

2007-01-26

389

The Natural Rate of Unemployment  

Microsoft Academic Search

This paper assesses the natural rate of unemployment—the unemployment rate that arises from all sources other than fluctuations in demand associated with business cycles. The natural rate is determined by the rate at which jobs are simultaneously created and destroyed, the rate of turnover in particular jobs, and how quickly unemployed workers are matched with vacant positions. Those factors in

David Brauer

2007-01-01

390

Specific Star Formation Rates  

E-print Network

We present results from a study to determine how star formation contributes to galaxy growth since redshift z=1.5. Using galaxies from the MUnich Near-Infrared Cluster Survey (MUNICS) and the FORS Deep Field (FDF), we investigate the specific star formation rate (SSFR, star formation rate [SFR] per unit galaxy stellar mass) as a function of galaxy stellar mass and redshift. We test the compatibility of our results with a sample drawn from a larger volume using the Sloan Digital Sky Survey. We find that the SSFR decreases as galaxy stellar mass increases, suggesting that star formation contributes more to the growth of low-mass galaxies than high-mass galaxies at all redshifts in this study. We also find a ridge in the SSFR that runs parallel to lines of constant SFR and decreases by a factor of 10 from z=1 to today, matching the results of the evolution in SFR density seen in the ``Lilly-Madau'' diagram. The ridge evolves independently of galaxy stellar mass to a particular turnover mass at the high mass end. Galaxies above the turnover mass show a sharp decrease in SSFR compared to the average at that epoch, and the turnover mass increases with redshift.

Amanda E. Bauer; Niv Drory; Gary J. Hill

2005-09-02

391

The Effects of Specific Respiratory Rates on Heart Rate and Heart Rate Variability  

Microsoft Academic Search

In this study respiratory rates of 3, 4, 6, 8, 10, 12, and 14 breaths per minute were employed to investigate the effects of these rates on heart rate variability (HRV). Data were collected 16 times at each respiratory rate on 3 female volunteers, and 12 times on 2 female volunteers. Although mean heart rates did not differ among these

Hye-Sue Song; Paul M. Lehrer

2003-01-01

392

Heart-Rate and Breath-Rate Monitor  

NASA Technical Reports Server (NTRS)

Circuit requiring only four integrated circuits (IC's) measures both heart rate and breath rate. Phase-locked loops lock on heart-rate and respiration-rate input signals. Each loop IC contains two phase comparators. Positive-edge-triggered circuit used in making monitors insensitive to dutycycle variations.

Cooper, T. G.

1983-01-01

393

Home bias, exchange rate disconnect, and optimal exchange rate policy  

Microsoft Academic Search

This paper examines how much the central bank should adjust the interest rate in response to real exchange rate fluctuations. The paper first demonstrates, in a two-country Dynamic Stochastic General Equilibrium (DSGE) model, that home bias in consumption is important to replicate the exchange rate volatility and exchange rate disconnect documented in the data. When home bias is high, the

Jian Wang

2010-01-01

394

Lindblad rate equations  

E-print Network

In this paper we derive an extra class of non-Markovian master equations where the system state is written as a sum of auxiliary matrixes whose evolution involve Lindblad contributions with local coupling between all of them, resembling the structure of a classical rate equation. The system dynamics may develops strong non-local effects such as the dependence of the stationary properties with the system initialization. These equations are derived from alternative microscopic interactions, such as complex environments described in a generalized Born-Markov approximation and tripartite system-environment interactions, where extra unobserved degrees of freedom mediates the entanglement between the system and a Markovian reservoir. Conditions that guarantees the completely positive condition of the solution map are found. Quantum stochastic processes that recover the system dynamics in average are formulated. We exemplify our results by analyzing the dynamical action of non-trivial structured dephasing and depola...

Budini, A A

2006-01-01

395

Lindblad rate equations  

E-print Network

In this paper we derive an extra class of non-Markovian master equations where the system state is written as a sum of auxiliary matrixes whose evolution involve Lindblad contributions with local coupling between all of them, resembling the structure of a classical rate equation. The system dynamics may develops strong non-local effects such as the dependence of the stationary properties with the system initialization. These equations are derived from alternative microscopic interactions, such as complex environments described in a generalized Born-Markov approximation and tripartite system-environment interactions, where extra unobserved degrees of freedom mediates the entanglement between the system and a Markovian reservoir. Conditions that guarantees the completely positive condition of the solution map are found. Quantum stochastic processes that recover the system dynamics in average are formulated. We exemplify our results by analyzing the dynamical action of non-trivial structured dephasing and depolarizing reservoirs over a single qubit.

Adrian A. Budini

2006-11-21

396

Interest Rates and Occupational Choice  

ERIC Educational Resources Information Center

The paper describes the labor supply effects of changes in the rate of interest on wage rates paid in generalized training occupations. The evidence appears to be consistent with the hypothesis that the rate of interest is a determinant of labor supply and is positively related to occupational wage rates. (Author)

Martin, Donald L.

1975-01-01

397

‘Think globally, act locally’China's rendezvous with MTV  

Microsoft Academic Search

Using the case of MTV China, this article examines how transnational media corporations have been extending into China where ideological control and joint business cooperation remain barriers for foreign capital. Based on interviews with personnel of MTV, as well as observations of their programme productions, this article explores how MTV localizes in China under various economic and political constraints. It

Anthony Fung

2006-01-01

398

Rendezvous Points-Based Scalable Content Discovery with Load Balancing  

E-print Network

"§©@¢!3X§EdwY@&'s(2Wy§EddF!§pIa"BIF¨'©1v!}S"'§©© W2&§$#2aT2'&A5¢'&#%&x9tYCB$WGQ@DGF!!¢Y`BE©CTgW@&§$#1a)(234{57¥¨8)G9aBT2!3¢&aD@Q@sTg3(23P '4|YCB$S©GBIDGF!Y@AT2a¢"'§E#'&¢(U§Id¨"§©©eV)2Q@"YcB3(@3'4 (2WG!"sBIF!Fv(c

Steenkiste, Peter

399

Optimizing the Earth-LISA "rendez-vous"  

E-print Network

We present a general survey of heliocentric LISA orbits, hoping it might help in the exercise of rescoping the mission. We try to semi-analytically optimize the orbital parameters in order to minimize the disturbances coming from the Earth-LISA interaction. In a set of numerical simulations we include nonautonomous perturbations and provide an estimate of Doppler shift and breathing as a function of the trailing angle.

Fabrizio De Marchi; Giuseppe Pucacco; Massimo Bassan

2011-07-14

400

A Low Cost Rendezvous Mission to 99942 Apophis  

Microsoft Academic Search

In recent years the public has become more aware of the potentially catastrophic consequences of an asteroid collision with Earth. Congress has taken note of this and instructed NASA to develop a program to determine the resources required to detect, track, characterize, and, if necessary, mitigate potentially hazardous objects. Characterization of an asteroid deemed sufficiently dangerous requires a space mission

Regan Howard; Ross Gillett

2007-01-01

401

Orbital rendezvous using an Augmented Lambert Guidance scheme  

E-print Network

The development of an Augmented Lambert Guidance Algorithm that matches the position and velocity of an orbiting target spacecraft is presented in this thesis. The Augmented Lambert Guidance Algorithm manipulates the inputs ...

MacLellan, Sara Jean

2005-01-01

402

Mars Sample Return Navigation: Rendezvous in Mars Orbit  

NASA Technical Reports Server (NTRS)

A mission to retrieve Martian rock and soil samples is under development by an international Mars Sample Return (MSR) design team managed by JPL. The first Martian samples are collected and launched into low Mars orbit in 2004.

Guinn, J.

1999-01-01

403

Usability of a mobile, group communication prototype while rendezvousing  

Microsoft Academic Search

Mobile phones are increasingly being used collaboratively by social networks of users in spite of the fact that they are primarily designed to support single users and one-to-one communication. It is not well understood how services such as group SMS, SMS-based discussion lists and mobile instant messaging (IM) will be used by mobile groups in natural settings. Studying specific instances

Jeff Axup; Stephen Viller; Nicola J Bidwell

2005-01-01

404

Genetic-algorithm-based fuzzy control of spacecraft autonomous rendezvous  

Microsoft Academic Search

The combination of the control capabilities of fuzzy logic with the learning capabilities of genetic algorithms is investigated. Fuzzy logic allows for the uncertainty inherent in most control problems to be incorporated into conventional expert systems. Although fuzzy-logic-based expert systems have been used successfully for controlling a number of physical systems, the tasks of selecting acceptable fuzzy membership functions and

L. Michael Freeman

1997-01-01

405

Reliable Self-Stabilizing Communication for Quasi Rendezvous  

E-print Network

called registers: rAB and rBA. Process A can write in the registers of rAB and each process A and B can = {a, b, c, } be an alphabet and w = aaabbbbcc = a3 b4 c2 a sequence of valuewritten by A into rAB

Boyer, Edmond

406

Trajectory Planning For Coordinated Rendezvous Of Unmanned Air Vehicles  

Microsoft Academic Search

A trajectory generation strategy that facilitatesthe coordination of multiple unmanned air vehiclesis developed. Of particular interest is the planning ofthreat-avoiding trajectories that result in the simultaneousarrival of multiple UAVs at their targets. Inthis approach, paths to the target are modeled usingthe physical analogy of a chain. A unique strengthof the planning approach is the ability to specify oralter the pathlength

Timothy W. Mclain; Randal W. Beard

2000-01-01

407

Technology of H-II Transfer Vehicle Rendezvous System  

NASA Astrophysics Data System (ADS)

The H-II Transfer Vehicle (HTV), which is a Japanese unmanned cargo transfer spacecraft, will deliver supplies to the International Space Station (ISS). The first HTV will be launched in 2009 from the Tanegashima Space Center aboard an H-IIB launch vehicle with up to 6,000kg of supplies. HTV approaches to the ISS and the Space Station Remote Manipulator System (SSRMS), known as Canadarm2, will grapple the HTV and berth it to the ISS. After the supplies, the HTV will then be loaded with waste materials and then separated from the ISS by SSRMS. HTV conducts departure sequence from ISS after release from SSRMS and reentry to the atmosphere. In this paper, technology of HTV automated Guidance, Navigation and Control (GN&C) system is presented.

Kasai, Toru; Ueda, Satoshi; Uematsu, Hirohiko

408

The ultimate rendezvous: microbial ecology meets industrial biotechnology  

E-print Network

. His lab has developed many genetic tools for designing bacteria destined for environmental release, synthesis and degradation reactions that have been so far the near exclusive realm of industrial environmental pollutants, both of which are badly needed by industry. How do we, as researchers in this field

McFall-Ngai, Margaret

409

Orbital Express AVGS Validation and Calibration for Automated Rendezvous  

NASA Technical Reports Server (NTRS)

From March to July of 2007, the DARPA Orbital Express mission achieved a number of firsts in autonomous spacecraft operations. The NASA Advanced Video Guidance Sensor (AVGS) was the primary docking sensor during the first two dockings and was used in a blended mode three other automated captures. The AVGS performance exceeded its specification by approximately an order of magnitude. One reason that the AVGS functioned so well during the mission was that the validation and calibration of the sensor prior to the mission advanced the state-of-the-art for proximity sensors. Some factors in this success were improvements in ground test equipment and truth data, the capability for ILOAD corrections for optical and other effects, and the development of a bias correction procedure. Several valuable lessons learned have applications to future proximity sensors.

Heaton, Andrew F.; Howard, Richard T.; Pinson, Robin M.

2008-01-01

410

Gemini - John W. Young in Rendezvous Docking Simulator  

NASA Technical Reports Server (NTRS)

Astronaut John Young (above) was one of 14 astronauts, 8 NASA test pilots, and 2 McDonnell test pilots who took part in simulator studies. Young piloted the simulator on November 12, 1963 Arthur Vogeley wrote: 'Many of the astronauts have flown this simulator in support of the Gemini studies and they, without exception, appreciated the realism of the visual scene. The simulator has also been used in the development of pilot techniques to handle certain jet malfunctions in order that aborts could be avoided. In these situations large attitude changes are sometimes necessary and the false motion cues that were generated due to earth gravity were somewhat objectionable; however, the pilots were readily able to overlook these false motion cues in favor of the visual realism.' Roy F. Brissenden wrote:'The basic Gemini control studies developed the necessary techniques and demonstrated the ability of human pilots to perform final space docking with the specified Gemini-Agena systems using only visual references. ... Results... showed that trained astronauts can effect the docking with direct acceleration control and even with jet malfunctions as long as good visual conditions exist.... Probably more important than data results was the early confidence that the astronauts themselves gained in their ability to perform the maneuver in the ultimate flight mission.'

1963-01-01

411

Rendezvous with the World: Missouri Southern State University's Themed Semesters  

ERIC Educational Resources Information Center

Although most universities emphasize study abroad as the primary vehicle to internationalize the campus, in reality only a small percentage of students actually participate in this endeavor. The internationally themed semesters at Missouri Southern State University (MSSU) reach virtually every student, and provide a global perspective and cultural…

Stebbins, Chad

2011-01-01

412

Rate of Lysozyme Crystallization  

NASA Astrophysics Data System (ADS)

We have observed the following: Free solution measurements of the electrophoretic mobility of hen egg-white lysozyme crystals grown in aqueous NaCl at 10 deg C at pH values between 3.6 and 5.7 demonstrate that the crystals are positively charged.(J.K. Baird, A.M. Holmes, and J.C. Clunie, Bull.Am.Phys.Soc. 41, 620 (1996)) (2) When the decaying concentration of uncrystallized lysozyme in the growth solution is monitored as a function of time, the log of the half-life decreases linearly with the square-root of the ionic strength. (3) Acid-base titration shows that lysozyme molecules in solution exist as highly charged cations.(R. Roxby and C. Tanford, Biochemistry 10, 3348 (1971)) These three observations combine to suggest that lysozyme crystallizes by addition of lysozyme cations to positively charged crystal nuclei and that the rate is accelerated by the presence of strong electrolytes.

Baird, J. K.; Clunie, J. C.

1997-03-01

413

Evolution of NEO rotation rates due to close encounters with Earth and Venus  

NASA Astrophysics Data System (ADS)

In this paper we study the statistical effect of planetary flybys on the rotation rates and states of Near Earth Objects (NEOs). Our approach combines numerical and analytical methods within a Monte Carlo model that simulates the evolution of the NEO spin rates. We take as input for the simulation a source distribution of spin states and evolve it to find their steady state distribution. In performing this evolution we track the changes in the spin rate and state distribution for the different components of the NEO population. We show that the cumulative effect of planetary encounters is to spin up the overall population of NEOs. This spin up effect holds on average only, and particular members of the population may experience an overall decrease in rotation rate. This effect is clearly seen across all components of the NEO population and is significant both statistically and physically. For initially slow rotators the spin up effect is strong, lowering the mean rotation period by 32%. For faster rotating populations the effect is less, lowering the spin period by 15% for the intermediate case, 6% for fast rotating rubble piles, and 8% for fast rotating monoliths. Physically, the spin up effect pushes 1% of the fast rotating rubble-pile NEOs over the disruption limit, while 6% of these bodies experience a sub-disruption event that could modify their physical structure. For monolithic NEOs, the spin up effect is self-limiting, reaching a minimum spin period of 1.1 hr, with a strong cut-off between 2-3 hr. This has two implications. First, it may not be necessary to invoke the rubble-pile hypothesis to recover a cut-off in spin period. Second, it shows that planetary flybys cannot account for the extremely rapid rotation rates of some small NEOs. We also tested a different balance between the effects of Earth and Venus by treating the Aten sub-class of asteroids separately. Due to increased interactions with the planets, the spin up effect is more pronounced (10%) and disruptions increase by a factor of three. The slow rotation tails of the spin distributions are increased to longer periods, in general, with rotation periods of over 100 hr occurring for a few tenths of a percent for some component populations. Thus, this mechanism may account for some of the noted excess in slow rotators among the NEOs. Planetary flybys also cause NEOs to enter a tumbling state, with approximately 0.5% of the population being placed into a long-axis rotation mode. Finally, based on the evolution of spin states of different components of the NEO population, we compared the evolved states with the measured distribution of NEOs to estimate the relative populations of these components that comprise the NEOs.

Scheeres, D. J.; Marzari, F.; Rossi, A.

2004-08-01

414

15 CFR 700.3 - Priority ratings and rated orders.  

Code of Federal Regulations, 2010 CFR

... (b) Persons receiving rated orders must give them preferential treatment as required by this regulation. This means a person...This provision ensures that suppliers will give priority treatment to rated orders from contractor to subcontractor to...

2010-01-01

415

Failure Rate - A Unified Approach.  

National Technical Information Service (NTIS)

Aging, of biological and mechanical systems, is well described as 'deterioration of the power to withstand destruction.' The failure rate concept is the mathematical way of describing aging. Failure rates have been defined for discrete and continuous time...

L. Lee, W. A. Thompson

1975-01-01

416

Erosion Rates and Mars Climate  

NASA Astrophysics Data System (ADS)

New erosion rate data during the past 20 Ma from fresh impact craters imaged by the Opportunity rover coupled with long-term erosion rates through time better constrain the link with the long term evolution of climate on Mars.

Golombek, M.; Warner, N.; Ganti, V.; Lamb, M.

2014-07-01

417

Slip Rates on young faults  

NSDL National Science Digital Library

Students use measured ages and offset of quaternary surfaces to determine vertical slip rates of a young fault. Students then must determine if vertical slip rates have varied significantly through time.

Huerta, Audrey

418

2007 Wholesale Power Rate Schedules : 2007 General Rate Schedule Provisions.  

SciTech Connect

This schedule is available for the contract purchase of Firm Power to be used within the Pacific Northwest (PNW). Priority Firm (PF) Power may be purchased by public bodies, cooperatives, and Federal agencies for resale to ultimate consumers, for direct consumption, and for Construction, Test and Start-Up, and Station Service. Rates in this schedule are in effect beginning October 1, 2006, and apply to purchases under requirements Firm Power sales contracts for a three-year period. The Slice Product is only available for public bodies and cooperatives who have signed Slice contracts for the FY 2002-2011 period. Utilities participating in the Residential Exchange Program (REP) under Section 5(c) of the Northwest Power Act may purchase Priority Firm Power pursuant to the Residential Exchange Program. Rates under contracts that contain charges that escalate based on BPA's Priority Firm Power rates shall be based on the three-year rates listed in this rate schedule in addition to applicable transmission charges. This rate schedule supersedes the PF-02 rate schedule, which went into effect October 1, 2001. Sales under the PF-07 rate schedule are subject to BPA's 2007 General Rate Schedule Provisions (2007 GRSPs). Products available under this rate schedule are defined in the 2007 GRSPs. For sales under this rate schedule, bills shall be rendered and payments due pursuant to BPA's 2007 GRSPs and billing process.

United States. Bonneville Power Administration.

2006-11-01

419

Determinants of heart rate variability  

Microsoft Academic Search

Objectives. This study sought to examine clinical determinants of heart rate variability and to report normative reference values for eight heart rate variability measures.Background. Although the clinical implications of heart rate variability have been described, clinical determinants and normative values of heart rate variability measures have not been studied systematically in a large community-based population.Methods. The first 2 h of

Hisako Tsuji; Ferdinand J. Venditti; Emily S. Manders; Jane C. Evans; Martin G. Larson; Charles L. Feldman; Daniel Levy

1996-01-01

420

ANNUAL ADULT SURVIVAL RATES OF  

Microsoft Academic Search

The purposes of this study were (1) to determine annual adult survival rates from banding data for each sex of the Brown-headed Cowbird (Molothrus ater), Common Grackle (Quiscalus quiscula), Red-winged Blackbird (Agelaius phoeniceus), and Starling (Sturnus vulgaris), and (2) to compare survival rates calculated from band returns with survival rates calculated from band recoveries. Others have studied annual adult survival

DON P. FANKHAIJSER

421

Heart rate conditioning in mice  

Microsoft Academic Search

Two strains of highly inbred mice were given classical conditioning with noise as CS and shock as US. Control groups for pseudoconditioning were included, and heart rate was measured before and after conditioning. Heart rate was elevated after conditioning (ppp=0.02). There was also a significant (p<0.01) main effect of strain on heart rate.

T. F. Herrmann; A. B. Carran

1972-01-01

422

Morningstar ratings and future performance  

Microsoft Academic Search

AbstractMorningstar is one of the major ratings suppliers of Australian managed funds. Ratings are a convenient information source for investors. Over time the ratings methodology used by Morningstar in Australia has become more like its North American counterpart. However, Morningstar Australia uniquely retains a commitment to a qualitative dimension to their research. This paper explores the relationship between Morningstar, qualitative

Paul Gerrans

2006-01-01

423

Hummingbirds as net rate maximisers  

Microsoft Academic Search

The behaviour of foraging hummingbirds can be accounted for by assuming the maximisation of net rate. The currency, net energy per unit volume consumed suggested by Montgomerie et al. (1984), is shown to be an unnecessary means of interpreting behaviour when compared alongside an extended net rate model. The reason for the failure of previous net rate models to account

Alasdair I. Houston; David C. Krakauer

1993-01-01

424

All about Heart Rate (Pulse)  

MedlinePLUS

All About Heart Rate (Pulse) Updated:Sep 30,2014 What should you know about your heart rate? Even if you’re not an athlete, ... Where is it and what is a normal heart rate? The best places to find your pulse ...

425

Estimating loss rates with TCP  

Microsoft Academic Search

Estimating loss rates along a network path is a problem that has received much attention within the research community. However, deriving accurate estimates of the loss rate from TCP transfers has been largely unaddressed. In this paper, we first show that using a simple count of the number of retransmissions yields inaccurate estimates of the loss rate in many cases.

Mark Allman; Wesley M. Eddy; Shawn Ostermann

2003-01-01

426

Discharge ratings at gaging stations  

USGS Publications Warehouse

A discharge rating is the relation of the discharge at a gaging station to stage and sometimes also to other variables. This chapter of 'Techniques of Water-Resources Investigations' describes the procedures commonly used to develop simple ratings where discharge is related only to stage and the most frequently encountered types of complex ratings where additional factors such as rate of change in stage, water-surface slope, or index velocity are used. Fundamental techniques of logarithmic plotting and the applications of simple storage routing to rating development are demonstrated. Computer applications, especially for handheld programmable calculators, and data handling are stressed.

Kennedy, E. J.

1984-01-01

427

Civilian Residential Fire Fatality Rates: Six High-Rate States Versus Six Low-Rate States.  

National Technical Information Service (NTIS)

The report presents results of an analysis of 1,600 fire fatalities occurring in six states with high fire-death rates and six states with low fire-death rates. Reasons for the differences in rates are explored, with special attention to victim age, sex, ...

J. R. Hall, S. G. Helzer

1983-01-01

428

7 CFR 1779.33 - Interest rates.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Interest rates. 1779.33 Section 1779...GUARANTEED LOANS § 1779.33 Interest rates. (a) General. Rates...may be either fixed or variable rates. Interest rates will be those rates...

2010-01-01

429

Equilibrium exchange rate theories under flexible exchange rate regimes  

Microsoft Academic Search

Economic theory refers to several notions of the exchange rate equilibrium value in a flexible exchange rate regime. It has been defined as that consistent with : a) the equilibrium of trade balance; b)the equilibrium of current account; c) the overall equilibrium of the balance of payments; d) the absence of speculative attacks on foreign exchange markets; e) the absence

Rosaria Rita Canale

2002-01-01

430

Withdrawal Rates, Savings Rates, and Valuation-Based Asset Allocation  

Microsoft Academic Search

While most everyone would agree that valuations matter, the question remains as to whether clients with a long-term outlook (such as those planning for retirement) can hope to act successfully on information about valuations. This article provides favorable evidence based on the historical record for long-term conservative investors to obtain improved retirement planning outcomes (lower savings rates, higher withdrawal rates)

Wade Donald Pfau

2011-01-01

431

Conducting Market Rate Surveys and Establishing Rate Policies.  

ERIC Educational Resources Information Center

Market rate surveys and the rate-setting policies and reimbursement rules informed by them are at the core of the market-based approach to child care and are central to the delicate balancing act of ensuring access to subsidized care while at the same time promoting the quality of child care. This report provides an overview of the market-based…

Karolak, Eric; Collins, Ray; Stoney, Louise

432

MONTHLY DENTAL RATES for Retirees  

E-print Network

MONTHLY DENTAL RATES for Retirees Effective 7/1/2012 - 6/30/2013 UNDER 65 Dental Rates Delta Dental.00 $17.00 Family $40.00 $14.00 $35.00 $19.00 $29.00 $25.00 Delta Dental Premier (High Option) Annualized.00 $69.00 $59.00 OVER 65 Dental Rates Delta Dental PPO (Low Option) Delta Dental Premier (High Option

New Mexico, University of

433

Rating Scales in Psychotherapy Practice  

Microsoft Academic Search

\\u000a Therapists can gain invaluable information by administering rating scales to clients throughout the therapy process. Indeed,\\u000a research has demonstrated therapists who utilize client feedback can improve their clients’ outcomes. We provide an overview\\u000a of the research of using rating scales in therapy. Next, we describe some practical considerations in the selection of rating\\u000a scales; specifically, we highlight the benefits and

Jesse Owen; Zac Imel

434

Poisson process with fuzzy rates  

Microsoft Academic Search

In a stochastic homogeneous Poisson process, interarrival times are independent and identically distributed (iid) exponential\\u000a random variables whose parameter is called the rate of the process. By using fuzzy variables to describe the parameter, a\\u000a Poisson process whose rates are fuzzy variables is established. Based on the random fuzzy theory, relationship between the\\u000a renewal number and fuzzy rates is discussed.

Shunqin Li

2010-01-01

435

A new silicon rate gyroscope  

Microsoft Academic Search

HSG-IMIT is developing a new silicon rate gyroscope of very small size, low cost, and high performance. The device is called MARS-RR, which means micromachined angular rate sensor with two rotary oscillation modes. First prototypes, MARS-RRI yielded random walk and bias stability as low as 0.27 deg\\/?h and 65 deg\\/h, respectively. The noise equivalent rate (3 ?) corresponds to a

W. Geiger; B. Folkmer; J. Merz; H. Sandmaier; W. Lang

1998-01-01

436

Incentive Rates- At What Cost?  

E-print Network

from the Tenth Annual Industrial Energy Technology Conference, Houston, TX, September 13-15, 1988 order by the Texas PUC in which we were ordered to file a cost based interruptible rate. At the time of that order, I do not believe that there were any... marginally costed rates in place in the state. The intervenors, whom had argued in favor of cost based rate, had hoped that I would file an average fuel, average O&M, and small administrative charge rate since there were no capacity costs associated...

Schaeffer, S. C.

437

ratings  

Cancer.gov

Informative 36 36 37 37 Interesting 23 30 23 35 Meaningful 23 28 --- --- Relevant 28 29 25 29 Something you could relate to 36 37 37 34 Told you something important 23 25 28 28 Told you something new 30 28 26 27 Worth remembering 22 33 19 --- 1 This table, based on the Ipsos-ASI, Inc., Market Research Database of Diagnostic Norms, includes national averages for standard copy test questions used in testing commercial ads.

438

Toronto bicycle commuter safety rates.  

PubMed

This analysis uses data from a survey of Toronto commuter cyclists that collected information regarding accident history as well as regular commute route to work or school. By relating the route information of the 1196 respondents to facility attributes in a Geographic Information System (GIS), defensible estimates of travel exposure on roads, off-road paths and sidewalks were developed. The rate of collision on off-road paths and sidewalks was lower than for roads. The relative rates for falls and injuries suggest these events are least common on-road followed by off-road paths, and finally most common on sidewalks. The rate of major injuries, an injury that required medical attention, was greatest on sidewalks and the difference between paths and sidewalks was negligible. These rates suggest a need for detailed analysis of sidewalk and off-road path bicycle safety. The absolute event rates per bicycle kilometer were found to be between 26 and 68 times higher than similar rates for automobile travel, re-confirming the urgent bicycle safety crisis. Examination of rates for sub-groups of cyclists suggest that experience is an important factor in bicycle safety. The same survey conducted in Ottawa, Canada found event rates much lower than Toronto. This result may confirm urban form, traffic levels and attitude do affect bicycle safety. The analysis also demonstrates a successful method to quantify bicycle travel exposure information and should be considered for further use as complement to other existing techniques. PMID:10487343

Aultman-Hall, L; Kaltenecker, M G

1999-11-01

439

Final Pilot Performance Rating Scales.  

ERIC Educational Resources Information Center

These rating scales are intended for evaluation of student pilot performance. Each student is evaluated individually on the basis of video recordings of the student in flight. Ten point rating lines are used for the ten criterion performance elements of each of three maneuvers, (1) Final Turn to Landing, (2) Lazy Eight, and (3) Vertical S "A".…

Horner, Walter R.; And Others

440

Pyrolysis rates of biomass materials  

Microsoft Academic Search

A method is proposed by which pyrolysis rates of biomass materials can be predicted from the species compositions in terms of the basic constituents (cellulose, hemicellulose and lignin) and their individual kinetic parameters. The activation energies, frequency factors and reaction orders for cellulose, hemicellulose and lignin have been determined in a conventional manner. The measured rates of pyrolysis of different

T. Rajeswara Rao; Atul Sharma

1998-01-01

441

Graduation Rates Fall for Athletes.  

ERIC Educational Resources Information Center

Graduation rates of National Collegiate Athletic Association (NCAA) Division I scholarship athletes have shown the first across-the-board decline since the Association began publishing rates in 1990. Much attention this year has focused on male basketball players; only 41% of those who entered college in 1991 graduated within six years. Many leave…

Haworth, Karla

1998-01-01

442

Evolution & the Cesarean Section Rate  

ERIC Educational Resources Information Center

"Nothing in biology makes sense except in the light of evolution." This was the title of an essay by geneticist Theodosius Dobzhansky writing in 1973. Many causes have been given for the increased Cesarean section rate in developed countries, but biologic evolution has not been one of them. The C-section rate will continue to rise, because the…

Walsh, Joseph A.

2008-01-01

443

RECYCLING RATE STUDY Prepared by  

E-print Network

NATIONAL RECYCLING RATE STUDY Prepared by: Smith, Bucklin and Associates, Inc. Market Research and Statistics Division Chicago, Illinois July 2003 PRINTED ON RECYCLED PAPER #12;BCI RECYCLING RATE STUDY TABLE ....................................................................................................1 II. METHODOLOGY A. Total Pounds of Lead Recycled from Batteries

Laughlin, Robert B.

444

Rating Scale Instruments and Measurement  

ERIC Educational Resources Information Center

The article examines theoretical issues associated with measurement in the human sciences and ensuring data from rating scale instruments are measures. An argument is made that using raw scores from rating scale instruments for subsequent arithmetic operations and applying linear statistics is less preferable than using measures. These theoretical…

Cavanagh, Robert F.; Romanoski, Joseph T.

2006-01-01

445

Regulation of Human Heart Rate  

NSDL National Science Digital Library

Students learn how to measure heart rate accurately. Then students design and carry out an experiment to test the effects of an activity or stimulus on heart rate, analyze and interpret the data, and present their experiments in a poster session. In this activity students learn about both cardiac physiology and experimental method.

Waldron, Ingrid

446

Inflation and the savings rate  

Microsoft Academic Search

In this paper we examine two explanations of the observed positive relationship between inflation rates and savings rates in Canada and the United States. Several models are estimated using quarterly time-series data from both countries, and the best of these are subjected to a variety of tests. One of the two explanations appears to be broadly consistent with the data.

Russell Davidson; James G. MacKinnon

1983-01-01

447

Inflation and the Savings Rate  

Microsoft Academic Search

This paper examines two explanations of the observed positive relationship between inflation rates and saving rates in Canada and the United States. Several models are estimated using quarterly time series data from both countries, and the best of these are subjected to a variety of tests. One of the two explanations appears broadly consistent with the data. The observed relationship

Russell Davidson; James G. MacKinnon

1982-01-01

448

Inflation and the Saving Rate  

Microsoft Academic Search

This paper provides a simple explanation for the observed positive relationship between savings rates and inflation rates in modern Western economies. We argue that this relationship arises because, in times of inflation, measured income and savings overestimate the corresponding real quantities. This explanation is compared with one recently advanced by Deaton. Both models are then estimated using American and Canadian

Russell Davidson; James G. MacKinnon

1979-01-01

449

Matching and Conditioned Reinforcement Rate  

ERIC Educational Resources Information Center

Attempts to examine the effects of variations in relative conditioned reinforcement rate on choice have been confounded by changes in rates of primary reinforcement or changes in the value of the conditioned reinforcer. To avoid these problems, this experiment used concurrent observing responses to examine sensitivity of choice to relative…

Shahan, Timothy A.; Podlesnik, Christopher A.; Jimenez-Gomez, Corina

2006-01-01

450

Descriptive Analysis of Student Ratings  

ERIC Educational Resources Information Center

Let X be a statistical variable representing student ratings of University teaching. It is natural to assume for X an ordinal scale consisting of k categories (in ascending order of satisfaction). At first glance, student ratings can be summarized by a location index (such as the mode or the median of X) associated with a convenient measure of…

Marasini, Donata; Quatto, Piero

2011-01-01

451

Innovative Rates Program. Final report  

SciTech Connect

Title II of the Energy Conservation and Production Act (ECPA) as amended by the Public Utility Regulatory Policies Act (PURPA) provided financial assistance to state