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1

Modified Proportional Navigation Scheme for Rendezvous and Docking with Tumbling Targets: The Planar Case.  

National Technical Information Service (NTIS)

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, ...

N. Fitz-coy M. Liu

1995-01-01

2

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.

3

Rendezvous facilities  

SciTech Connect

The concurrent programming facilities in both Concurrent C and the Ada language are based on the rendezvous concept. Although these facilities are similar, there are substantial differences. Facilities in Concurrent C were designed keeping in perspective the concurrent programming facilities in the Ada language and their limitations. Concurrent C facilities have also been modified as a result of experience with its initial implementations. In this paper, the authors compare the concurrent programming facilities in Concurrent C and Ada, and show that it is easier to write a variety of concurrent programs in Concurrent C than in Ada.

Gehani, N.H.; Roome, W.D.

1988-11-01

4

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

5

Autonomous rendezvous in elliptical orbits  

Microsoft Academic Search

An important feature of the autonomous terminal rendezvous of spacecraft in an elliptical orbit is a periodic motion (limit cycle) in the system variables. Unstable limit cycle involves an instability of the system. This paper addresses a mathematical model of the system, a range rate control algorithm, a numerical iterative method for computing the limit cycle, its stability and domain

Y. Shaohua

1997-01-01

6

CTV rendezvous techniques  

NASA Astrophysics Data System (ADS)

The cargo transfer vehicle (CTV) requires the capability to perform automated rendezvous with Space Station Freedom (SSF) using onboard sensors and algorithms. The current approach to CTV rendezvous applies techniques developed during the orbital maneuvering vehicle (OMV) program which have been mechanized for automatic, onboard execution. The initial catch up sequence can be described as a passive rendezvous without explicit time of arrival control. The ultimate requirement for this rendezvous technique is to place the CTV on the SSF V-bar axis at some specified downrange distance. The launch vehicle will use yaw steering during orbit injection to achieve the proper phantom plane for nodal biasing. This presentation describes the primary components of the CTV rendezvous scheme.

Jennings, Jerry L.; Anderson, Robert L.

7

Optimal control of aerial tethers for payload rendezvous  

Microsoft Academic Search

The exciting concept of using a tether deployed from an aircraft to rendezvous with a ground-based location is successfully demonstrated in this paper. By manipulating the cable attachment point position and the rate of change of the cable's radial velocity, it can be shown that the tip of a cable being towed behind an aircraft can rendezvous with a surface

Pavel Trivailo; Daniel Sgarioto; Chris Blanksby

2004-01-01

8

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…

Colbert, Martin

2005-01-01

9

Rendezvous guidance with proportional navigation  

NASA Astrophysics Data System (ADS)

In this article, a new approach for rendezvous terminal guidance with proportional navigation is developed. Under this guidance scheme, the magnitude of commanded acceleration is programmed with modified proportional navigation and it is applied in a fixed direction with a bias angle to the normal direction of line-of-sight during rendezvous course. Then the solution of relative motion described in a polar coordinate can be easily obtained and the corresponding energy expenditure, which is related to propellant mass required for rendezvous in exoatmospheric flight, is also derived. From the result, we find that the rendezvous path is a form of spiral function and both commanded acceleration and relative velocity are maintained in fixed directions relative to line-of-sight during rendezvous course. Also, the energy expenditure required for exoatmospheric rendezvous is proportional to and greater than the initial relative velocity.

Yuan, Pin-Jar; Hsu, Shih-Che

1993-02-01

10

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

11

Effective run-and-tumble dynamics of bacteria baths.  

PubMed

E. coli bacteria swim in straight runs interrupted by sudden reorientation events called tumbles. The resulting random walks give rise to density fluctuations that can be derived analytically in the limit of non-interacting particles or equivalently of very low concentrations. However, in situations of practical interest, the concentration of bacteria is always large enough to make interactions an important factor. Using molecular dynamics simulations, we study the dynamic structure factor of a model bacterial bath for increasing values of densities. We show that it is possible to reproduce the dynamics of density fluctuations in the system using a free run-and-tumble model with effective fitting parameters. We discuss the dependence of these parameters, e.g., the tumbling rate, tumbling time and self-propulsion velocity, on the density of the bath. PMID:23999470

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

2013-09-03

12

Effective run-and-tumble dynamics of bacteria baths  

NASA Astrophysics Data System (ADS)

E. coli bacteria swim in straight runs interrupted by sudden reorientation events called tumbles. The resulting random walks give rise to density fluctuations that can be derived analytically in the limit of non-interacting particles or equivalently of very low concentrations. However, in situations of practical interest, the concentration of bacteria is always large enough to make interactions an important factor. Using molecular dynamics simulations, we study the dynamic structure factor of a model bacterial bath for increasing values of densities. We show that it is possible to reproduce the dynamics of density fluctuations in the system using a free run-and-tumble model with effective fitting parameters. We discuss the dependence of these parameters, e.g., the tumbling rate, tumbling time and self-propulsion velocity, on the density of the bath.

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

2013-10-01

13

Rendezvous radar for orbital vehicles  

NASA Astrophysics Data System (ADS)

In this paper some of the factors which relate to the system design of rendezvous radars are discussed and the system design and the capabilities of the OMV Rendezvous Radar System (RRS) are described. The potential for transferring manufacturing technologies and methods which have been developed for high-volume-production commercial and military hardware systems into the relatively low volume world of hi-rel electronics hardware for space is discussed.

Locke, John W.; Casey, Larry D.

1992-03-01

14

Modular Clock Algorithm for Blind Rendezvous.  

National Technical Information Service (NTIS)

A new algorithm, the modular clock algorithm, is developed and analyzed as a solution for the simple rendezvous environment model, coupled with a modified version for environment models with less information. This thesis examines the rendezvous problem as...

N. C. Theis

2009-01-01

15

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

16

Near Earth asteroid rendezvous  

NASA Astrophysics Data System (ADS)

The Spacecraft Design Course is the capstone design class for the M.S. in astronautics at the Naval Postgraduate School. The Fall 92 class designed a spacecraft for the Near Earth Asteroid Rendezvous Mission (NEAR). The NEAR mission uses a robotic spacecraft to conduct up-close reconnaissance of a near-earth asteroid. Such a mission will provide information on Solar System formation and possible space resources. The spacecraft is intended to complete a NEAR mission as a relatively low-budget program while striving to gather as much information about the target asteroid as possible. A complete mission analysis and detailed spacecraft design were completed. Mission analysis includes orbit comparison and selection, payload and telemetry requirements, spacecraft configuration, and launch vehicle selection. Spacecraft design includes all major subsystems: structure, electrical power, attitude control, propulsion, payload integration, and thermal control. The resulting spacecraft demonstrates the possibility to meet the NEAR mission requirements using existing technology, 'off-the-shelf' components, and a relatively low-cost launch vehicle.

1992-12-01

17

Asynchronous Deterministic Rendezvous on the Line  

Microsoft Academic Search

We study the rendezvous problem in the asynchronous setting in the graph of infinite line following the model introduced in (13) . We formulate gen- eral lemmas about deterministic rendezvous algorithms in this setting which char- acterize the algorithms in which the agents have the shortest routes. We also im- prove rendezvous algorithms in the infinite line which formu lated

Grzegorz Stachowiak

2009-01-01

18

Aerodynamic Characteristics of a Tumbling Plate under Free Flight  

NASA Astrophysics Data System (ADS)

In this study, we deal with the tumbling, which is a rotating motion with the axis perpendicular to the falling direction. Our purpose is to reveal the fundamental aerodynamic characteristics of the tumbling, experimentally. Regarding a test plate, we consider a prism with a rectangular cross section with a depth-to-width ratio ? of 0.3. The results are as follows. The reduced terminal rotating rate ?*, the lift coefficient CL, the drag coefficient CD and the lift-to-drag ratio CL/CD are independent of the aspect ratio AR, when AR is greater than 10. As the inertia moment ratio I* increases from zero to 50, ?*, CL and CD increase. However, ?*, CL and CD become almost constant, at I* greater than 50. We propose the empirical formulae to predict them. At low I*, the tumbling shows a dominant periodicity of 360 deg.

Hirata, Katsuya; Shimizu, Kosuke; Fukuhara, Kensuke; Yamauchi, Kazuki; Kawaguchi, Daisuke; Funaki, Jiro

19

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

20

Rendezvous radar for the orbital maneuvering vehicle  

NASA Astrophysics Data System (ADS)

The rendezvous radar set (RRS) under development will be a key subsystem aboard NASA's new orbital maneuvering vehicle (OMV). The RRS is an X-band all solid-state, monopulse tracking, frequency-hopping, pulse-Doppler radar system. Targets of 1m2 are detected at ranges greater than 4.5 nautical miles, and larger targets are detected at up to 10 nautical miles. The target is then tracked in angle, range, and range rate to a distance of 35 feet from the OMV. In addition to performance and cost, the design drivers for the RRS development have included the minimization of power consumption, size, and weight.

Locke, John W.; Olds, Keith A.; Ohe, Thomas D.

21

STS-134: Rendezvous Pitch Maneuver  

NASA Video Gallery

On May 18, 2011, space shuttle Endeavour performed the Rendezvous Pitch Maneuver, or "backflip." With Commander Mark Kelly at the helm, Endeavour rotated 360 degrees backward to enable International Space Station astronauts to take high resolution pictures of the shuttle's heat shield.

John Kossum

2011-05-18

22

Rendezvous maneuvers using Genetic Algorithm  

NASA Astrophysics Data System (ADS)

The present paper has the goal of studying orbital maneuvers of Rendezvous, that is an orbital transfer where a spacecraft has to change its orbit to meet with another spacecraft that is travelling in another orbit. This transfer will be accomplished by using a multi-impulsive control. A genetic algorithm is used to find the transfers that have minimum fuel consumption.

Souza dos Santos, Denílson Paulo; Rodrigo Barretto Teodoro, Anderson; Bertachini de Almeida Prado, Antônio F.

2013-10-01

23

CABLE ASSISTED RENDEZVOUS FOR AIRCRAFT WITH SURFACE LOCATIONS  

Microsoft Academic Search

By systematically altering the in-plane flight path and velocity of an aircraft and the rate at which the cable is deployed, the tip of a cable being towed behind an aircraft is shown to rendezvous with a ground-based surface location in minimum time, with minimum control effort required. This is achieved through optimal control, formulated as a nonlinear programming problem

Daniel Sgarioto; Pavel Trivailo

24

Rendezvous and docking with remote piloted vehicles  

NASA Astrophysics Data System (ADS)

The man-in-the-loop control system requirements for the Orbital Maneuvering Vehicle (OMV) are examined. Since many similarities exist between the Teleoperator Retrieval System (TRS) and the unfolding OMV concept, a review of the TRS control system baseline along with selected design trades which led to that baseline are discussed. TRS program issues relevant to the man-in-the-loop control system design include thruster size, communication delays and TV bandwidth compression, range/range rate radar, tumbling targets, shimmed docking interface, and control system definition. A TRS vs. OMV simulation comparative study is summarized, and the major issues currently facing the control system designer on OMV are discussed.

Micheal, J. D.

25

Shuttle rendezvous radar performance: evaluation and simulation  

Microsoft Academic Search

The authors describe the performance evaluation and simulation of the Ku-band shuttle rendezvous radar. Computer simulation, using the radar cross section for specific spacecraft, provided an estimate of rendezvous radar range performance for that spacecraft. The radar cross section model included smooth metallic surfaces, rough surfaces, and shadowing effects, as well as phase differences due to different path lengths to

J. W. Griffin; A. C. Lindberg; T. B. Ahn; P. L. Harton

1989-01-01

26

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

NASA Astrophysics Data System (ADS)

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.

27

Photometric Analysis of the Very Long Period and Tumbling Asteroid 1278 Kenya  

NASA Astrophysics Data System (ADS)

1278 Kenya is a long period main-belt asteroid. It was observed in collaboration among four photometrists located over two months at widely spaced locations. This asteroid is in non-principal axis (NPA) rotation, also known as tumbling. The primary period was determined to be 188 ± 1 h with a candidate second period of 127 ± 1 h. The quality of the tumbling solution is rated as PAR= ˜2, tending to ˜3.

Oey, Julian; Pilcher, Frederick; Benishek, Vladimir; Higgins, David; Pravec, Petr

2012-04-01

28

Orbiter Servicer Rendezvous Simulation (ORSIM)  

NASA Astrophysics Data System (ADS)

Orbiter Servicer Rendezvous Simulation (ORSIM) is an automated tool that simulates sequential transfer maneuvers of an orbital maneuvering vehicle (OMV) transporting orbital replaceable units from a space-based depot, or logistics platform, to higher altitude SDI sdatellites. ORSIM calculates OMV energy expenditures (velocity changes) and event histories for various combinations of user-selected orbital transfer maneuvers. Additionally, ORSIM determines the optimal configuration/quantities of logistics platforms and OMVs which conform to the dynamics of differential nodal precession, given user-prescribed values of the scheduled maintenance cycle and required servicing times. ORSIM is coded in FORTRAN-77 and is resident on an IBM PC/AT.

Amato, Amiel; Hoffman, Mickie D.

29

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 to enable space station astronauts to take high resolution pictures of the shuttle's heat shield. Lindsey then flew the shuttle through a quarter circle to a position about 310 feet directly in front of the station, allowing the station to catch up with it for docking at 2:16 p.m.

Mark Garcia

2011-02-27

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

14 CFR 1214.111 - Rendezvous services.  

Code of Federal Regulations, 2013 CFR

... General Provisions Regarding Space Shuttle Flights of Payloads for Non-U...involves the rendezvous of the Space Shuttle orbiter with an orbiting spacecraft...spacecraft deployed earlier on the same Space Shuttle flight. (2) Exchange...

2013-01-01

32

Soviet automated rendezvous and docking system overview  

NASA Astrophysics Data System (ADS)

The Soviets have been performing automated rendezvous and docking for many years. This paper will present an overview and brief history of the Soviet AR&D system, based on the open literature and publicly available sources.

Hinman, Elaine M.; Bushman, David M.

33

Averaged run-and-tumble walks  

NASA Astrophysics Data System (ADS)

A random walk consisting of a run phase at constant speed interrupted by tumble events is analyzed and analytically solved for arbitrary time distributions. A general expression is given for the Laplace-Fourier transform of the probability density function and for the mean square displacement averaging over initial conditions. Run-and-tumble bacteria and Lévy walks are considered as particular cases. The effects of an underlying Brownian noise are also discussed. Derived expressions can be used for a direct comparison with experimentally measured quantities.

Angelani, L.

2013-04-01

34

A closer look at tumbling toast  

Microsoft Academic Search

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

M. E. Bacon; George Heald; Matt James

2001-01-01

35

Orion Handling Qualities During ISS Rendezvous and Docking.  

National Technical Information Service (NTIS)

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 ma...

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

2011-01-01

36

Relative Navigation Requirements for Automatic Rendezvous and Capture Systems.  

National Technical Information Service (NTIS)

This paper will discuss in detail the relative navigation system requirements and sensor trade-offs for Automatic Rendezvous and Capture. Rendezvous navigation filter development will be discussed in the context of navigation performance requirements for ...

P. M. Kachmar R. J. Polutchko W. Chu M. Montez

1991-01-01

37

Rendezvous radar for the orbital maneuvering vehicle  

NASA Astrophysics Data System (ADS)

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

38

Soviet automated rendezvous and docking system overview  

Microsoft Academic Search

The Soviets have been performing automated rendezvous and docking for many years. It has been a reliable mode of resupply and reboost. During the course of the Soviet space program, the autodocking system has evolved. The earlier IGLA system was replaced with the current KURS system. Both systems are radar-based. The variation in strength between antennas is used for computing

Elaine M. Hinman; David M. Bushman

1991-01-01

39

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

NASA Astrophysics Data System (ADS)

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

40

Autonomous Rendezvous and Docking Conference, volume 3  

NASA Astrophysics Data System (ADS)

This document consists of the presentation submitted at the Autonomous Rendezvous and Docking (ARD) Conference. The document contains three volumes: ARD hardware technology; ARD software technology; and ARD operations. The purpose of this conference is to identify the technologies required for an on orbit demonstration of ARD, assess the maturity of these technologies, and provide the necessary insight for a quality assessment of programmatic management, technical, schedule, and cost risks.

41

Autonomous Rendezvous and Docking Conference, volume 1  

NASA Astrophysics Data System (ADS)

This document consists of the presentation submitted at the Autonomous Rendezvous and Docking (ARD) Conference. It contains three volumes: ARD hardware technology; ARD software technology; and ARD operations. The purpose of this conference is to identify the technologies required for an on orbit demonstration of the ARD, assess the maturity of these technologies, and provide the necessary insight for a quality assessment of the programmatic management, technical, schedule, and cost risks.

42

Tumbling and spaceflight: the Gemini VIII experience.  

PubMed

A malfunctioning orbital flight attitude thruster during the flight of Gemini VIII led to acceleration forces on astronauts Neil Armstrong (commander) and David Scott (pilot) that created the potential for derogation of oculo-vestibular and eye-hand coordination effects. The spacecraft attained an axial tumbling rotation of 50 rpm and would have exceeded this had not the commander accurately diagnosed the problem and taken immediate corrective action. By the time counter-measure controls were applied, both astronauts were experiencing vertigo and the physiological effects of the tumbling acceleration. Data from the recorders reveal that one astronaut experienced -Gy of 0.92 G-units, and the other +Gy of 0.92 for approximately 46 s. Both received a -Gz of 0.89 G-units from the waist up with a +Gz of 0.05 from the waist down. A substantial increase of time and/or an increase in rpm would ultimately have produced incapacitation of both astronauts. NASA corrected the Gemini thruster problem by changing the ignition system wiring. Future space-craft undertaking long-term missions could be equipped with unambiguous thruster fault displays and could have computer-controlled automatic cutoffs to control excessive thruster burns. PMID:2302130

Mohler, S R; Nicogossian, A E; McCormack, P D; Mohler, S R

1990-01-01

43

Trajectory control with continuous thrust applied to a rendezvous maneuver  

NASA Astrophysics Data System (ADS)

A rendezvous mission can be divided into the following phases: launch, phasing, far range rendezvous, close range rendezvous and mating (docking or berthing). This paper aims to present a close range rendezvous with closed loop controlled straight line trajectory. The approaching is executed on V-bar axis. A PID controller and continuous thrust are used to eliminate the residual errors in the trajectory. A comparative study about the linear and nonlinear dynamics is performed and the results showed that the linear equations become inaccurate insofar as the chaser moves away from the target.

Santos, W. G.; Rocco, E. M.

2013-10-01

44

Performance modeling of the Ada rendezvous. Final report  

SciTech Connect

The Ada Programming Language (United States Department of Defense, 1983) was designed to meet the need for a standard computer-programming language. Ada has the ability to take advantage of microprocessor environments. One feature, known as the rendezvous, allows tasks to synchronize. This very important and powerful feature is poorly understood. Rendezvous performance is a known area of concern, especially if the system is in a multiprocessor environment. In this paper, analytic techniques are developed that will predict the performance of systems using the rendezvous. In a distributed Ada system, the rendezvous provides synchronized communication between asynchronous tasks. A system of this sort would consist of at least two processors, each serving various tasks. We have analytically developed algorithms that determine the average Rendezvous Response Time for a two-processor system. Rendezvous Response Time will be defined as the amount of time one task (i.e., a client task) must wait until its rendezvous request to another task (i.e., a server task) is completed. This approach uses Mean Value Analysis (MVA), analytic extensions to MVA, and elementary queueing theory to decompose the rendezvous into interacting separate models. The notion of a software server that maintains a queue and services rendezvous requests will play an important part in the solution techniques.

Sterrett, A.E.; Minei, M.K.

1991-10-01

45

Research on rendezvous and docking technology  

NASA Astrophysics Data System (ADS)

The following reviews were conducted on rendezvous and docking technology: (1) second design and review on the Rendezvous and Docking (RVD) technology for the Engineering Test Satellite-7 (ETS-7), such as RVD on orbit experiments, RVD experiment system; (2) second RVD system test research, such as integration test of the onboard software, RVD operation support function software, detail review on system research tests, and RVD system research equipment production; (3) first research on the rendezvous and Global Positioning System (GPS) correlated navigation, such as system design and ground test method review; (4) research on high accuracy GPS receiver, such as high accuracy receiving technology and design review on high accuracy receiver system; (5) trial production and test of the critical components for GPS receiver, including design review on trial production and test of the critical components for and trial production and test of the proximity sensors; and (6) trial production and test of the proximity sensors, including the system design, trial production and test of components and system evaluation models.

Ichikawa, Shinichirou; Kawano, Isao; Suzuki, Hiroyuki; Yamada, Mitsuru

1992-08-01

46

Flight operations for Shuttle rendezvous navigation and targeting  

Microsoft Academic Search

An important mission for the Space Shuttle is orbital rendezvous with free-flying satellites for repair and refurbishment. The recent successful rescue of the Solar Maximum Mission (SMM) satellite by the Space Shuttle Challenger emphasizes this fact. The task of completing a rendezvous is one that requires the capability to track the target satellite and autonomously determine the maneuvers necessary to

D. J. Collins

1984-01-01

47

Evaluation of Head-Up Displays for teleoperated Rendezvous & Docking  

Microsoft Academic Search

Rendezvous & Docking will be an essential part for many future spaceflight activities, like manned or unmanned exploration of the Moon or Near Earth Objects (NEOs), a Mars Sample Return mission, as well as On-Orbit Servicing or Space Debris Removal activities. While autonomy is expected to play a major role in future Rendezvous & Docking, human operators on the ground

Markus Wilde; Sean C. Hannon; Ulrich Walter

2012-01-01

48

Rendezvousing with location-aware devices: Enhancing social coordination  

Microsoft Academic Search

Emerging technologies such as location-awareness devices have the potential 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 potential. This paper presents a field study investigating the use of mobile location-aware devices for rendezvous activities. Participants took part in one

David Dearman; Kirstie Hawkey; Kori M. Inkpen

2005-01-01

49

Rendezvous Planning in Wireless Sensor Networks with Mobile Elements  

Microsoft Academic Search

Recent research shows that significant energy saving can be achieved in wireless sensor networks by using mobile elements (MEs) capable of carrying data mechanically. However, the low movement speed of MEs hinders their use in data-intensive sensing applications with temporal constraints. To address this issue, we propose a rendezvous-based approach in which a subset of nodes serves as the rendezvous

Guoliang Xing; Tian Wang; Zhihui Xie; Weijia Jia

2008-01-01

50

Rendezvous Planning in Mobility-Assisted Wireless Sensor Networks  

Microsoft Academic Search

Research shows that significant energy saving can be achieved in wireless sensor networks by using mobile elements (MEs) capable of carrying data mechanically. However, the low movement speed of MEs hinders their use in data-intensive sensing applications with temporal constraints. To address this issue, we propose a rendezvous-based approach in which a subset of nodes serve as the rendezvous points

Guoliang Xing; Tian Wang; Zhihui Xie; Weijia Jia

2007-01-01

51

SIMONE: interplanetary microsatellites for NEO rendezvous missions  

NASA Astrophysics Data System (ADS)

The paper summarises a novel mission concept called SIMONE (Smallsat Intercept Missions to Objects Near Earth), whereby a fleet of microsatellites may be deployed to individually rendezvous with a number of Near Earth Objects (NEOs), at very low cost. The mission enables, for the first time, the diverse properties of a range of spectral and physical type NEOs to be determined. Such data are invaluable to the scientific study, impact damage prediction, and impact countermeasure planning of NEOs. The five identical 120kg spacecraft are designed for low-cost piggyback launch on Ariane-5 into GTO, from where each uses a gridded-ion engine to escape the Earth and ultimately to rendezvous with a different NEO target. The primary challenge with such a mission is the ability to accommodate the necessary electric propulsion, power, payload and other onboard systems within the constraints of a microsatellite. The paper describes the way in which the latest technological advancements have been selected and applied to the mission design. The SIMONE design is feasible and clearly demonstrates that the concept of an "interplanetary microsatellite" is now realisable.

Wells, Nigel; Walker, Roger; Green, Simon; Ball, Andrew

2003-11-01

52

SIMONE: Interplanetary microsatellites for NEO rendezvous missions  

NASA Astrophysics Data System (ADS)

The paper summarises a novel mission concept called SIMONE (smallsat intercept missions to objects near Earth), whereby a fleet of microsatellites may be deployed to individually rendezvous with a number of near Earth objects (NEOs), at very low cost. The mission enables, for the first time, the diverse properties of a range of spectral and physical type NEOs to be determined. Such data are invaluable to the scientific study, impact damage prediction, and impact countermeasure planning of NEOs. The five identical 120 kg spacecraft are designed for low-cost piggyback launch on Ariane-5 into GTO, from where each uses a gridded-ion engine to escape the Earth and ultimately to rendezvous with a different NEO target. The primary challenge with such a mission is the ability to accommodate the necessary electric propulsion, power, payload and other on-board systems within the constraints of a microsatellite. The paper describes the way in which the latest technological advancements have been selected and applied to the mission design. The SIMONE design is feasible and clearly demonstrates that the concept of an "interplanetary microsatellite" is now realisable.

Wells, Nigel; Walker, Roger; Green, Simon; Ball, Andrew

2006-10-01

53

Rendezvous radar for the orbital maneuvering vehicle  

NASA Astrophysics Data System (ADS)

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

54

Impact on aluminum plates by tumbling projectiles: Experimental study  

Microsoft Academic Search

An experimental investigation into the effects due to tumbling of 12.7 mm diameter, hard-steel, blunt-faced cylindrical projectiles with an LD ratio of 3 on the impact response of thin and moderately thick aluminum targets was performed. Projectiles were fired from a powder gun and tumbling motion was induced by a special generator. A high speed camera was employed to obtain

Kezhun Li; Werner Goldsmith

1996-01-01

55

Credit PSR. This interior view shows the vacuum tumble dryer. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Credit PSR. This interior view shows the vacuum tumble dryer. The tumble dryer is lined with a water jacket to maintain temperature during the drying of ammonium perchlorate ("AP"); water enters and exits the dryer jacket through the pipe fittings along the horizontal center line of the dryer. The wall at the right is constructed to blow out in the event of an explosion - Jet Propulsion Laboratory Edwards Facility, Oxidizer Dryer Building, Edwards Air Force Base, Boron, Kern County, CA

56

Comprehensive description of NMR cross-correlated relaxation under anisotropic molecular tumbling and correlated local dynamics on all time scales.  

PubMed

A simple general expression for the NMR cross-correlated relaxation rate under anisotropic molecular tumbling is presented for globular proteins. The derivation includes effects of fast and slow motion of the interaction tensors and correlation between them. Expressions suitable for practical analysis are tailored in dependence of standard order parameters of the individual interactions. It is shown that these order parameters must be sensitive to slow motion (slower than molecular tumbling) for detection of slow correlated motion. Such order parameters are those obtained from residual dipolar couplings but not those obtained from T1, T2, and heteronuclear Nuclear Overhauser Enhancement measurements. PMID:20614970

Vögeli, Beat

2010-07-01

57

Rendezvous Radar for the Orbital Maneuvering Vehicle (Abstract Only).  

National Technical Information Service (NTIS)

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 Di...

J. W. Locke K. A. Olds T. Quaid

1991-01-01

58

Rendezvous Terminal Phase Automatic Braking Sequencing and Targeting.  

National Technical Information Service (NTIS)

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 brakin...

P. M. Kachmar

1973-01-01

59

Supervised autonomous rendezvous and docking systems technology evaluations  

NASA Astrophysics Data System (ADS)

The Jet Propulsion Laboratory, employing the technology assessment that resulted from the Autonomous Rendezvous and Docking Conference held at the Lyndon B. Johnson Space Center on 15-16 Aug. 1990 as the basis undertook a literature search and contacts with major national and international aerospace companies to perform an assessment of the existing technologies and those that are needed to accomplish supervised autonomous rendezvous and docking in space. The following five issues are covered: (1) lessons learned; (2) technology assessment for navigation and guidance sensors for Autonomous Rendezvous and Docking (AR&D); (3) technology assessment of Guidance, Navigation and Controls (GN&C), techniques for rendezvous and docking; (4) docking mechanisms; and (5) space and ground operations.

Marzwell, Neville I.

60

The Way We Were: Improvising History at Rocky Mountain Rendezvous  

Microsoft Academic Search

Participants at today’s Rocky Mountain rendezvous dress in pre-1840 clothing and gather to camp in period shelters and engage in an assortment of history-based activities. These encampments, which last several days, evoke the Rocky Mountain rendezvous of fur traders and beaver trappers that occurred between the years 1825 and 1840. Rendezvousers usually describe what they are doing as re-enactment of

Page Anderson Rozelle

2004-01-01

61

Effects of Location-Aware Computing On Rendezvous Behaviour  

Microsoft Academic Search

This paper presents a field study investigating the behavioral effects of mobile location-aware computing on rendezvousing. Participants took part in one of three mobile device conditions (a mobile phone, a location-aware handheld, or both a mobile phone and a location-aware handheld) and completed rendezvousing scenarios. The results reveal key differences in communication patterns between the mediums, and in the type

David Dearman; Kirstie Hawkey; Kori M. Inkpen

62

Strategy for capturing of a tumbling space debris  

NASA Astrophysics Data System (ADS)

In general space debris objects do not possess much convenient features and are non-cooperative. In such cases, since the conditions for capture are not favorable, tracking errors will lead to loading, and momentum transfer will occur during the capture process. In most cases, detailed mass and inertial characteristics of the target are unknown, either because design details are unavailable or due to changes as a result of damage sustained when failure occurred or gradual degradation over the years, and this makes impedance matching of the capture arm force control system difficult. This led to us to devise a "joint virtual depth control" algorithm for robot arm control, which brakes the rotation of a target with unknown inertia. This paper deals with a removal work strategy and control method for capturing and braking a tumbling, non-cooperative target space debris. We propose a new brush type contactor as end-effecter of a robot arm for reducing the rotational rate of the target debris. As a means for relieving the loads generated during target tapping, in addition to joint compliance control we propose a new control method that controls the arm tip force according to a contact force profile.

Nishida, Shin-Ichiro; Kawamoto, Satomi

2011-01-01

63

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

64

Computational modelling and simulation of the elder tumble  

NASA Astrophysics Data System (ADS)

The Hanavan's fifteen rigid multi-body human model was simplified into the six rigid multi-body model, and then the six degrees of freedom The Kane dynamic model was set up. With the human body parameters and muscle parameters, the six degrees of freedom Kane formula and restriction conditions were used to obtain the elder tumble movement status when the feet were stopped suddenly. The initial rotation speed of each part of the body can be calculated. After that, the tumble movement of elder was stimulated and the impact force from the ground surface was obtained.

Han, Jia; Han, Chunying

2011-12-01

65

Rendezvous Between Two Spacecrafts with Coplanar Elliptic Orbits using Horizontal Impulse.  

National Technical Information Service (NTIS)

This article studies the problems of fixed time rendezvous between two spacecraft in general coplanar elliptical orbit under the effects of three horizontal impulses. Necessary conditions for completing rendezvous are derived, and methods are given for ca...

Y. Chen X. Wang M. He

1995-01-01

66

Visual Control for Multirobot Organized Rendezvous.  

PubMed

This paper addresses the problem of visual control of a set of mobile robots. In our framework, the perception system consists of an uncalibrated flying camera performing an unknown general motion. The robots are assumed to undergo planar motion considering nonholonomic constraints. The goal of the control task is to drive the multirobot system to a desired rendezvous configuration relying solely on visual information given by the flying camera. The desired multirobot configuration is defined with an image of the set of robots in that configuration without any additional information. We propose a homography-based framework relying on the homography induced by the multirobot system that gives a desired homography to be used to define the reference target, and a new image-based control law that drives the robots to the desired configuration by imposing a rigidity constraint. This paper extends our previous work, and the main contributions are that the motion constraints on the flying camera are removed, the control law is improved by reducing the number of required steps, the stability of the new control law is proved, and real experiments are provided to validate the proposal. PMID:22394581

López-Nicolás, Gonzalo; Aranda, Miguel; Mezouar, Youcef; Sagüés, Carlos

2012-03-02

67

WISE Observations of Rendezvous Mission Candidate Comets  

NASA Astrophysics Data System (ADS)

In 1992, Osip et al. wrote: "Several comet flyby and/or rendezvous missions are currently being planned, for which supporting groundbased data from previous apparitions should prove useful. Here, we discuss groundbased narrowband photometry obtained over the last 15 years for nine candidate comets, five of which have been observed on multiple apparitions -- we derive limits on the size of each cometary nucleus. In order to facilitate spacecraft mission planning, we also present molecular abundance ratios, note variations in cometary activity as a function of orbital position and between apparitions, and note the overall degree of dustiness. A detailed analysis of the characteristics of these nine viable mission candidates will provide necessary information for prioritizing targets for any future missions." In this work, we update Osip et al.'s 1992 work using recent photometric infrared observations of the best candidate comet spacecraft targets observed by WISE and other (IRAS, MSX, ISO, Spitzer) infrared space telescopes. The comets studied include 2P/Encke, 9P/Tempel 1, 10P Tempe1 2, 19P/Borrelly, 22P/Kopff, 67P/Churyumov-Gerasimenko, 81P/Wild, 103P/Hartley 2, 107P/Wilson-Harrington. We present imagery, photometry, and temporal trend data, and derived estimates of the dust mass, spatial distribution, albedo/emissivity, and PSD for each comet.

Lisse, Carey M.; Bauer, J. M.; Fernandez, Y. R.; Mainzer, A. K.; Walker, R. G.; Meech, K. J.; Grav, T.; Weissman, P. R.; Kramer, E.; Stevenson, R.

2012-10-01

68

Soviet automated rendezvous and docking system overview  

NASA Astrophysics Data System (ADS)

The Soviets have been performing automated rendezvous and docking for many years. It has been a reliable mode of resupply and reboost. During the course of the Soviet space program, the autodocking system has evolved. The earlier IGLA system was replaced with the current KURS system. Both systems are radar-based. The variation in strength between antennas is used for computing relative positions and attitudes. The active spacecraft has a transponder. From discussions with Soviet engineers, it seems the docking process can be controlled either from the ground or from the active (docking) spacecraft's onboard computer. The unmanned Progress resupply ships regularly dock with the current MIR Space Station. The Soyuz T spacecraft incorporated the IGLA system, and the later Soyuz TM and Progress M Series spacecraft incorporated the KURS. The MIR Complex has both systems installed. The rear port and the KVANT docking port have the IGLA system installed to support earlier Progress ships that use the IGLA. The first Soyuz TM docking occurred in May of 1986, while the first Progress M docked in September of 1989.

Hinman, Elaine M.; Bushman, David M.

69

Spacecraft rendezvous operational considerations affecting vehicle systems design and configuration  

NASA Astrophysics Data System (ADS)

One lesson learned from Orbiting Maneuvering Vehicle (OMV) program experience is that Design Reference Missions must include an appropriate balance of operations and performance inputs to effectively drive vehicle systems design and configuration. Rendezvous trajectory design is based on vehicle characteristics (e.g., mass, propellant tank size, and mission duration capability) and operational requirements, which have evolved through the Gemini, Apollo, and STS programs. Operational constraints affecting the rendezvous final approach are summarized. The two major objectives of operational rendezvous design are vehicle/crew safety and mission success. Operational requirements on the final approach which support these objectives include: tracking/targeting/communications; trajectory dispersion and navigation uncertainty handling; contingency protection; favorable sunlight conditions; acceptable relative state for proximity operations handover; and compliance with target vehicle constraints. A discussion of the ways each of these requirements may constrain the rendezvous trajectory follows. Although the constraints discussed apply to all rendezvous, the trajectory presented in 'Cargo Transfer Vehicle Preliminary Reference Definition' (MSFC, May 1991) was used as the basis for the comments below.

Prust, Ellen E.

70

Aquapod: Prototype design of an amphibious tumbling robot  

Microsoft Academic Search

As mobile robots decrease in size so does their ability to traverse rough terrain. New forms of locomotion beyond the basic wheel are being explored to overcome this fault. This paper expands on the mechanical design of a previous robot with a high mobility-to-size ratio. To accomplish high mobility the robot uses tumbling as its form of locomotion. By actively

Andrew Carlson; Nikos Papanikolopoulos

2011-01-01

71

Investigation of the Tumbling Phenomenon Using Computer Simulation.  

National Technical Information Service (NTIS)

A single degree-of-freedom free-to-pitch simulation of the X-29A was developed and used to investigate the tumble susceptibility of the X-29A with its controls fixed. Validation of the ability of the aerodynamic models used in this simulation to accuratel...

S. P. Fears

1985-01-01

72

Necessary conditions for tumbling in the rotational motion  

NASA Astrophysics Data System (ADS)

The goal of this work is the investigation of the necessary conditions for the possible existence of tumbling in rotational motion of rigid bodies. In a stable spinning satellite, tumbling may occur by sufficient strong action of external impulses, when the conical movement characteristic of the stable attitude is de-characterized. For this purpose a methodology is chosen to simplify the study of rotational motions with great amplitude, for example free bodies in space, allowing an extension of the analysis to non-conservative systems. In the case of a satellite in space, the projection of the angular velocity along the principal axes of inertia must be known, defining completely the initial conditions of motion for stability investigations. In this paper, the coordinate systems are established according to the initial condition in order to allow a simple analytical work on the equations of motion. Also it will be proposed the definition of a parameter, calling it tumbling coefficient, to measure the intensity of the tumbling and the amplitude of the motion when crossing limits of stability in the concept of Lyapunov. Tumbling in the motion of bodies in space is not possible when this coefficient is positive. Magnus Triangle representation will be used to represent the geometry of the body, establishing regions of stability/instability for possible initial conditions of motion. In the study of nonconservative systems for an oblate body, one sufficient condition will be enough to assure damped motion, and this condition is checked for a motion damped by viscous torques. This paper seeks to highlight the physical understanding of the phenomena and the influence of various parameters that are important in the process.

Carrera, Danny H. Z.; Weber, Hans I.

2012-11-01

73

Endoscopic retrograde cholangiopancreatography with rendezvous cannulation reduces pancreatic injury  

PubMed Central

AIM: To examine whether rendezvous endoscopic retrograde cholangiopancreatography (ERCP) is associated with less pancreatic damage, measured as leakage of proenzymes, than conventional ERCP. METHODS: Patients (n = 122) with symptomatic gallstone disease, intact papilla and no ongoing inflammation, were prospectively enrolled in this case-control designed study. Eighty-one patients were subjected to laparoscopic cholecystectomy and if intraoperative cholangiography suggested common bile duct stones (CBDS), rendezvous ERCP was performed intraoperatively (n = 40). Patients with a negative cholangiogram constituted the control group (n = 41). Another 41 patients with CBDS, not subjected to surgery, underwent conventional ERCP. Pancreatic proenzymes, procarboxypeptidase B and trypsinogen-2 levels in plasma, were analysed at 0, 4, 8 and 24 h. The proenzymes were determined in-house with a double-antibody enzyme linked immunosorbent assay. Pancreatic amylase was measured by an enzymatic colourimetric modular analyser with the manufacturer’s reagents. All samples were blinded at analysis. RESULTS: Post ERCP pancreatitis (PEP) occurred in 3/41 (7%) of the patients cannulated with conventional ERCP and none in the rendezvous group. Increased serum levels indicating pancreatic leakage were significantly higher in the conventional ERCP group compared with the rendezvous ERCP group regarding pancreatic amylase levels in the 4- and 8-h samples (P = 0.0015; P = 0.03), procarboxypeptidase B in the 4- and 8-h samples (P < 0.0001; P < 0.0001) and trypsinogen-2 in the 24-hour samples (P = 0.03). No differences in these markers were observed in patients treated with rendezvous cannulation technique compared with patients that underwent cholecystectomy alone (control group). Post procedural concentrations of pancreatic amylase and procarboxypeptidase B were significantly correlated with pancreatic duct cannulation and opacification. CONCLUSION: Rendezvous ERCP reduces pancreatic enzyme leakage compared with conventional ERCP cannulation technique. Thus, laparo-endoscopic technique can be recommended with the ambition to minimise the risk for post ERCP pancreatitis.

Swahn, Fredrik; Regner, Sara; Enochsson, Lars; Lundell, Lars; Permert, Johan; Nilsson, Magnus; Thorlacius, Henrik; Arnelo, Urban

2013-01-01

74

Robust h ? control for spacecraft rendezvous with a noncooperative target.  

PubMed

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

2013-08-20

75

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.

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

2013-01-01

76

A Study on Rendezvous Docking Control of the HOPE  

NASA Astrophysics Data System (ADS)

A study on rendezvous docking control of the HOPE is presented. The HOPE is the Japanese version of unmanned space shuttle, which requires the automatic rendezvous docking guidance algorithm. In this paper, the thruster combination algorithm is implemented by using linear programming (LP) method for minimum fuel consumption. The automatic guidance algorithms for three approaching phases are developed. The numerical simulation by these algorithms showed good result. The thruster combination algorithm by LP, the determination algorithm of the thruster firing timing by C-W-Hill’s equation, and the technique for implementing the simulation are explained in detail.

Hashizume, Yuji; Imado, Fumiaki; Murota, Akira

77

Simulations of the tumbling and tank treading motions of cells immersed in fluid flow  

NASA Astrophysics Data System (ADS)

We describe the development of computational techniques to study the deformation of cells modeled as liquid capsules enclosed by thin shells suspended in fluid flow. Computations are performed for cells with spherical, ellipsoidal and biconcave unstressed shapes over a wide range of the dimensionless shear rate and for a broad range of the ratio of the internal to surrounding fluid viscosities. Results for small deformations of initially spherical capsules are in quantitative agreement with analytic predictions. Under large deformations, the results show that spherical capsules deform to stationary configurations and the membranes undergo steady tank-treading motion. For capsules of ellipsoidal and biconcave unstressed shapes, the capsules exhibit either tumbling, tank-treading of the membrane about the viscous interior with periodic oscillations of the orientation angle, or intermittent behaviour in which the two modes occur alternately depending on the viscosity, membrane elasticity and shear rate. Our method provides an efficient way to study the tank-treading-to-tumbling transition of red blood cells in shear flows as the shear rate decreases. Observations of such motions may provide a sensitive mean of assessing cell membrane properties. Finally, we also describe simulations of the long-time behavior of a dense suspension of red-blood cells in a micro-channel to illustrate the efficiency of the method.

Chiam, Keng-Hwee; Le, Duc Vinh

2009-11-01

78

Sub-optimized rendez-vous approach sequence  

Microsoft Academic Search

A possible rendezvous approach sequence at constant line of sight angle and with a suboptimized total impulse is considered. The technique is compared, via simulation program, with a constant radial acceleration technique. It is found that the total impulse requirement of the optimized method is always less than the relevant requirement of the constant acceleration method. The real fuel consumption

P. Magnani; A. Gallo

1985-01-01

79

Automatic Rendezvous and Capture System Development in a Manned Environment.  

National Technical Information Service (NTIS)

This paper presents the development of a 'Phase One' AR&C system capability as a logical outgrowth of Rendezvous and Proximity Operations (R&PO) system development for manned space programs. The continuity of the approach to R&PO across the Apollo, Skylab...

P. M. Kachmar W. L. Jackson

1991-01-01

80

Multiple NEO Rendezvous, Reconnaissance and In Situ Exploration  

NASA Astrophysics Data System (ADS)

We propose a two spacecraft rendezvous with multiple NEOs. A two spacecraft mission mimics architecture for human explorers to use a mother ship to get from Earth to the NEO and a small body lander for in situ investigation on or close to the NEO.

Klaus, K.; Elsperman, M. S.; Smith, D. B.; Cook, T. S.

2011-03-01

81

The rendezvous technique for the treatment of choledocholithiasis  

Microsoft Academic Search

Background: The rendezvous technique combines endoscopy with percutaneous transhepatic cholangiography to facilitate cannulation of the bile duct when previous attempts have failed. Methods: Over a 7-year period, a total of 1753 ERCPs were performed. Twelve of these patients with a diagnosis of choledocholithiasis were poor candidates for surgery. Percutaneous transhepatic cholangiography as well as ERCP with precut papillotomy failed to

Mari M. Calvo; Luis Bujanda; Iñaki Heras; José L. Cabriada; Antonio Bernal; Victor Orive; José Miguelez

2001-01-01

82

Minimum-time orbital rendezvous between neighboring elliptic orbits  

Microsoft Academic Search

Time-optimal rendezvous maneuvers are studied. The system considered consists of a target vehicle (nonmaneuvering vehicle) in a known elliptic orbit and an interceptor vehicle (maneuvering vehicle) in a neighboring elliptic orbit such that the ratio of the distance between the two vehicles to the radius of the target-vehicle orbit is small. The interceptor vehicle has propulsive jet systems which can

K. T. Alfriend; Y. Kashiwagi

1969-01-01

83

Tumbling approach towards template-free synthesis of EMT zeolite  

Microsoft Academic Search

The zeolite EMT has been synthesized with 18-crown-6\\/Al2O3 ratios as low as 0.14, by applying continuous tumbling of the synthesis mixture during the entire aging and crystallization period. The crystalline product contained only two crown ether molecules per unit cell, and the mother liquor was essentially free of crown ether. It was found that the lower the amount of crown

Rune Wendelbo; Michael Stöcker; Hanne Junggreen; Helle B Mostad; Duncan E Akporiaye

1999-01-01

84

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

NASA Astrophysics Data System (ADS)

TALON (Tumble Arresting Large Oscillation Nullifier), a device capable of capturing a target in an uncontrolled three-axis tumble, and CRADLE (Concentric Rotating Astronaut Detumble Lifesaving Equipment), a device for rescuing a suited astronaut, are discussed. The physical nature of the tumbling problem is reviewed and the TALON/CRADLE system is described. A detailed examination of the way that TALON/CRADLE calculates the target motions and make appropriate adjustments is given.

Idle, Dunning, V.

1991-08-01

85

Effects of Phosphate Type on the Quality of Vacuum-Tumbled Catfish Fillets  

Microsoft Academic Search

The objective of this study was to determine the effects of various agglomerated phosphate blends on the quality of vacuum-tumbled catfish fillets. Catfish fillets were tumbled with a brine solution at 15% over initial, raw weight prior to tray-packing and storage at 4°C for 10 days. Fillets were evaluated for protein exudate, tumbling yield, color, pH, cooking loss, tenderness, purge

Sovann Kin; M. Wes Schilling; Juan L. Silva; Brian S. Smith; Viodelda Jackson; Taejo Kim

2009-01-01

86

Effect of phosphate with tumbling on lipid oxidation of precooked roast beef  

Microsoft Academic Search

This study was a 4×2×4 factorial experiment, sodium tripolyphosphate (0, 0.25, 0.4 and 0.5%), tumbling (nontumbled and tumbled), and storage time (day 0, 2, 4 and 7). Cooking yield was dependent on the level of phosphate and tumbling. For thiobarbituric acid reactive substances (TBARS) values, only sodium tripolyphosphate level and storage time had a significant two-way interaction. The TBARS value

Jen-hua Cheng; Herbert W. Ockerman

2003-01-01

87

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

88

Sub-optimized rendez-vous approach sequence  

NASA Astrophysics Data System (ADS)

A possible rendezvous approach sequence at constant line of sight angle and with a suboptimized total impulse is considered. The technique is compared, via simulation program, with a constant radial acceleration technique. It is found that the total impulse requirement of the optimized method is always less than the relevant requirement of the constant acceleration method. The real fuel consumption requirement of the two methods is approximately the same for low initial distances (some kilometers). For high initial distances (tens of kilometers), the total fuel requirement for the optimized method can be considerably lower than for the other method. When the rendezvous directions are about 90 deg, however, the requirement is about the same.

Magnani, P.; Gallo, A.

1985-10-01

89

Using advanced industrial robotics for spacecraft Rendezvous and Docking simulation  

Microsoft Academic Search

One of the most challenging and risky missions for spacecraft is to perform Rendezvous and Docking (RvD) autonomously in space. To ensure a safe and reliable operation, such a mission must be carefully designed and thoroughly verified before a real space mission can be launched. This paper describes a new, robotics-based, hardware-in-the-loop RvD simulation facility which uses two industrial robots

Toralf Boge; Ou Ma

2011-01-01

90

Automatic rendezvous and capture system development in a manned environment  

Microsoft Academic Search

This paper presents the development of a 'Phase One' AR&C system capability as a logical outgrowth of Rendezvous and Proximity Operations (R&PO) system development for manned space programs. The continuity of the approach to R&PO across the Apollo, Skylab, Apollo-Soyuz, and Shuttle programs is traced and lessons learned which are applicable to AR&C discussed. Use of the Shuttle as a

Peter M. Kachmar; William L. Jackson

1991-01-01

91

Early postmortem injection and tumble marination effects on broiler breast meat tenderness.  

PubMed

Several processors use inline injection and tumble marination practices to decrease labor costs and product handling. However, the stimulation of this early postmortem (PM) muscle may cause increased toughness. Therefore, the objective of this study was to compare marination of early PM meat by using injection, vacuum tumbling, or both to determine their effects on tenderness of broiler breast fillets. Breast fillets from 45 broilers were deboned at 3 h PM and injected, tumbled (30 min, 635 mmHg, 14 rpm), or injected + tumbled with a 10% solution of 0.54%. NaCl + 0.42% sodium tripoly phosphate (STPP). Nonmarinated controls deboned at 3 and 6 h PM were also included. Shear value, sarcomere length, and cook loss were determined on each of the fillets. The control and tumbled fillets had the highest shear value compared with the remaining 3-h treatments. The injected + tumbled and tumbled fillets had the highest cook loss followed by 3-h control and injected treatments. Tumble marination at 3 h PM produced significantly tougher meat then the injection treatment. Experiment 2 was conducted to test marinade penetration through the fillets because penetration could have affected the results of the previous study. Broiler breast fillets were deboned from 60 broilers at 3 h PM and were vacuum tumbled (30 min, 635 mmHg, 14 rpm) with a 15% solution of 0.54% NaCl and 0.42% STPP. We determined shear value and cooked meat moisture of the fillets and sodium ion migration into the fillets. Although there were no significant differences in shear value between control and tumbled fillets, the cooked meat moisture was significantly higher in tumbled fillets when compared with the controls. Sodium ion concentration was significantly higher on the surface (especially the lateral surface) of the fillets when compared with the center, which suggested some uneven distribution. PMID:15206633

Alvarado, C Z; Sams, A R

2004-06-01

92

76 FR 37663 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Tumbling Creek...  

Federal Register 2010, 2011, 2012, 2013

...alteration in the quantity of groundwater and alteration of spring discharge...as well as areas within the recharge area of Tumbling Creek cave...Although the above-ground recharge area of Tumbling Creek Cave...alteration in the quantity of groundwater and spring discharge...

2011-06-28

93

75 FR 35751 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Tumbling Creek...  

Federal Register 2010, 2011, 2012, 2013

...surface runoff and groundwater sources (springs and...in the quantity of groundwater and alteration of spring...as areas within the recharge area of Tumbling Creek...Although the above ground recharge area of Tumbling Creek...525), decrease groundwater levels...

2010-06-23

94

Multi-robot, multi-rendezvous recharging paradigm: An opportunistic control strategy  

Microsoft Academic Search

This paper presents an opportunistic control ap- proach to address the multi-robot, multi-rendezvous recharging problem. The control strategy adapted attempts to take advan- tages of both centralized as well as distributed methodologies while addressing the problem. Every robotic agent of the group is equipped with a decision engine that scores available rendezvous locations that are obtained via communicating with mother

Soheil Keshmiri

2011-01-01

95

SEP Encke-87 and Halley Rendezvous Studies and Improved S/C Model Implementation in HILTOP.  

National Technical Information Service (NTIS)

Studies were conducted to determine the performance requirements for projected state-of-the-art SEP spacecrafts boosted by the Shuttle/IUS to perform a rendezvous with the comet Halley and a rendezvous with the comet Encke during its 1977 apparition. The ...

J. L. Horsewood F. I. Mann

1978-01-01

96

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

97

Time-Fixed Rendezvous by Impulse Factoring with an Intermediate Timing Constraint.  

National Technical Information Service (NTIS)

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 aline...

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

1974-01-01

98

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

NASA Astrophysics Data System (ADS)

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.

Krüger, Timm; Gross, Markus; Raabe, Dierk; Varnik, Fathollah

99

Guidance laws for spacecraft pursuit-evasion and rendezvous  

NASA Astrophysics Data System (ADS)

Nonlinear feedback guidance laws are developed for a pursuit-evasion differential game between two spacecraft, and for the more traditional spacecraft rendezvous problem using the complete nonlinear point-mass models. These guidance laws are suitable for on-board implementation. They are applicable for large amplitude maneuvers and can account for the presence of more than one gravitational field. An exact method for computing time-to-go required in guidance law implementation is developed. The guidance law performance is demonstrated using a three-degree-of-freedom simulation with a six harmonic gravitational model.

Menon, P. K. A.; Calise, A. J.; Leung, S. K. M.

100

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

NASA Astrophysics Data System (ADS)

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

101

ESR Studies of the Slow Tumbling of Vanadyl Spin Probes in Nematic Liquid Crystals.  

National Technical Information Service (NTIS)

ESR line shapes that are appropriate for slowly tumbling vanadyl spin probes in viscous nematic liquid crystals were calculated by the stochastic Liouville method. Because of the symmetry possessed by vanadyl, the analysis and interpretation of these line...

M. P. Eastman G. V. Bruno J. O. Lawson

1977-01-01

102

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

103

Quantitative characterization of agglomerate abrasion in a tumbling blender by using the Stokes number approach.  

PubMed

Removal of microcrystalline cellulose agglomerates in a dry-mixing system (lactose, 100 M) predominantly occurs via abrasion. The agglomerate abrasion rate potential is estimated by the Stokes abrasion (StAbr) number of the system. The StAbr number equals the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. Basically, the StAbr number concept describes the blending condition of the dry-mixing system. The concept has been applied to investigate the relevance of process parameters on agglomerate abrasion in tumbling blenders. Here, process parameters such as blender rotational speed and relative fill volumes were investigated. In this study, the StAbr approach revealed a transition point between abrasion rate behaviors. Below this transition point, a blending condition exists where agglomerate abrasion is dominated by the kinetic energy density of the powder blend. Above this transition point, a blending condition exists where agglomerates show (undesirable) slow abrasion rates. In this situation, the blending condition is mainly determined by the high fill volume of the filler. PMID:23250711

Willemsz, Tofan A; Nguyen, Tien Thanh; Hooijmaijers, Ricardo; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

2012-12-19

104

Tumbling dynamics of isolated polymer chains in strong shear flows and the effects of chain resolution  

NASA Astrophysics Data System (ADS)

Using Brownian dynamics simulations, without hydrodynamic and excluded volume interactions, on polymer chain models encompassing a wide range of resolutions, we present a detailed investigation on the behavior of isolated chains in shear flow. We find a highly non-monotonic behavior for all models, with chain compression occurring at ultra-high shear rates that is consistent with the recent simulation studies. However, results obtained using highly refined models, with resolutions lower than a Kuhn step, reveal that this transition is an artifact of the level of chain discretization. Also, our results clearly indicate that, at high shear rates, the chain thickness in the shear-gradient direction is independent of the chain length, which differ from previously reported scaling law. We show that the chain thickness is fixed by the distance a sub-section of the chain can diffuse in the shear-gradient direction before convection stretches it out and suppresses further diffusion. Simple physical arguments are then used to derive the correct scaling laws for the coil width and the tumbling time at high shear rates. We believe that our findings presented here will provide the foundation for a better understanding of this basic problem in polymer dynamics.

Larson, Ronald; Saha Dalal, Indranil; Albaugh, Alex; Hoda, Nazish

2012-02-01

105

Near Earth Asteroid Rendezvous: the science of discovery  

NASA Astrophysics Data System (ADS)

The Near Earth Asteroid Rendezvous (NEAR) mission, the first in NASA's Discovery Program, launched on 17 February 1996. Almost 4 years later (14 February 2000) the NEAR spacecraft (NEAR Shoemaker) began the first orbital study of an asteroid, the near-Earth object 433 Eros. NEAR Shoemaker completed its mission on 12 February 2001 by landing on the asteroid and acquiring data from its surface. In addition to its detailed study of the S-type asteroid 433 Eros, NEAR Shoemaker also performed the first flyby measurements of a C-type asteroid, 253 Mathilde, en route to its target destination. This successful mission has provided a new wealth of discoveries in the field of asteroid science and has led to new lines of thought about asteroids, their formation, and their evolution.

Domingue, Deborah L.; Cheng, Andrew F.

2002-01-01

106

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

107

Exploring the Behavioural Effects of Location-Aware Computing While Rendezvousing  

Microsoft Academic Search

This paper presents an exploratory field study investigating the behavioral effects of mobile location-aware computing on rendezvousing. We introduce a study where participants took part in one of three mobile device conditions (a mobile phone, a location-aware handheld or both a mobile phone and a location-aware handheld) and completed three different rendezvousing scenarios. We discuss the difference in communication patterns

David Dearman; Kirstie Hawkey; Kori Inkpen

108

Rendezvous Regions: A Scalable Architecture for Service Location and Data-Centric Storage in Large-Scale Wireless Networks  

Microsoft Academic Search

Summary form only given. In large-scale wireless networks such as mobile ad hoc and sensor networks, efficient and robust service discovery and data-access mechanisms are both essential and challenging. Rendezvous-based mechanisms provide a valuable solution for provisioning a wide range of services. We describe rendezvous regions (RRs) - a novel scalable rendezvous-based architecture for wireless networks. RR is a general

Karim Seada; Ahmed Helmy

2004-01-01

109

Selection of rendezvous sites and reuse of pup raising areas among wolves Canis lupus of north-eastern Apennines, Italy  

Microsoft Academic Search

A coarse scale analysis was carried out of factors affecting rendezvous site selection and fidelity to pup raising areas in\\u000a wolfCanis lupus Linnaeus, 1758 packs inhabiting the north eastern Apennines, Italy. From 1993 to 2004, 44 rendezvous sites were identified,\\u000a and compared with random sites for variables related to topography, habitat, and human presence. Rendezvous sites were significantly\\u000a more frequent

Claudia Capitani; Luca Mattioli; Elisa Avanzinelli; Andrea Gazzola; Paolo Lamberti; Lorenza Mauri; Massimo Scandura; Alessia Viviani; Marco Apollonio

2006-01-01

110

3D aspects of mixing and transport in tumbled granular flow  

NASA Astrophysics Data System (ADS)

The exploration of the kinematic structures that emerge in 3D flows has only just begun (see, e.g., Focus on Fluids in JFM vol. 654, 2010). Tumbled granular flow in a spherical container rotated sequentially about two distinct axes is a convenient physical system in which to investigate these issues. The flow can "switch" between 2D motion (dynamics restricted to 2D manifolds) and fully-3D motion depending on the choice of angles of rotation about the axes. We compute explicitly the action- action-angle transformation, period along trajectories and exact location of normally- hyperbolic and elliptic period-one curves from the piecewise-defined nonlinear dynamical system. This provides the basis for a definition of a 3D notion of an "island." These theoretical results also allow for the "optimization" of the angles of rotation in the protocol. An extensive numerical investigation of the "goodness of mixing" is performed using Danckwerts' intensity of segregation I. By fitting the decay rate and asymptotic value of I, we can understand the effects of the protocol parameters and how mixing varies across the volume of the tumbler. Finally, we establish the existence of "adiabatic" structures (2D manifolds exhibiting chaotic and ergodic dynamics) and study the persistence of these barriers to radial transport as the flow is perturbed into the fully-3D regime.

Christov, Ivan C.; Lueptow, Richard M.; Ottino, Julio M.; Sturman, Rob; Wiggins, Stephen

2010-11-01

111

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

112

Improvement on the electrochemical characteristics of graphite anodes by coating of the pyrolytic carbon using tumbling chemical vapor deposition  

Microsoft Academic Search

The electrochemical characteristics of graphite coated with pyrolytic carbon materials using tumbling chemical vapor deposition (CVD) process have been studied for the active material of anodes in lithium ion secondary batteries. Coating of pyrolytic carbons on the surface of graphite particles, which tumble in a rotating reactor tube, was performed through the pyrolysis of liquid propane gas (LPG). The surface

Young-Soo Han; Jai-Young Lee

2003-01-01

113

The Effects of Egg White, Tumbling and Storage Time on Proximate Composition and Protein Fractions of Restructured Fish Product  

Microsoft Academic Search

This research evaluated the alterations of fish muscle with added non-fish protein which was tumbled and then restructured, cooked and stored to produce an innovative restructured fish product. Significant differences were found in the moisture and lipid content and pH of tumbled, egg white added, and stored treatments of catfish muscle. Moisture content of the processed and control groups of

H. Yetim; H. W. Ockerman

1995-01-01

114

Pollinators' mating rendezvous and the evolution of floral advertisement.  

PubMed

Successful cross-fertilization in plant species that rely on animal pollinators depends not just on the number of pollinator visits, but also on these visits' duration. Furthermore, in non-deceptive pollination, a visit's duration depends on the magnitude of the reward provided to the pollinator. Accordingly, plants that rely on biotic pollination have to partition their investment in cross-fertilization assurance between attracting pollinator visits - advertisement, and rewarding visitors to assure that the visit is of productive duration. Here we analyze these processes by a combination of optimality methods and game theoretical modeling. Our results indicate that the optimality in such allocation of resources depends on the types of reward offered to the pollinators. More precisely, we show that plants that offer both food reward and mating rendezvous to pollinators will evolve to allocate a higher proportion of their cross-fertilization assurance budget to advertisement than plants that offer only food reward. That is, our results indicate that pollinators' mating habits may play a role in floral evolution. PMID:23023108

Fishman, Michael A; Hadany, Lilach

2012-09-27

115

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

116

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

117

Hydrodynamic effects on the tumbling of flagellated bacteria near a solid surface  

NASA Astrophysics Data System (ADS)

Peritrichously flagellated bacteria use semi-rigid helical flagella to form a bundle during a run to swim forward and to trigger the unbundling during a tumble to change their swimming direction. It is accepted that the hydrodynamic interactions play a significant role in these processes. Recently, using digital holographic microscopy and microfluidics, we discovered that the tumbling events are substantially suppressed near a solid wall. In this paper, we present a two flagellum rigid model to elucidate the hydrodynamic wall interaction mechanism behind the phenomenon. Further implications on cell attachment and detachment during the biofilm formation will be discussed. We apply Slender Body Theory (SBT) to quantify the flow flagellum interaction. The no-slip boundary imposed by the wall is modeled using the image system of the SBT model for the stoke-flow singularity. We show that in the bulk, a repulsive force among flagella initiates the unbundling and consequently tumbling; however, in presence of the wall, the force is strongly mitigated that stabilize the bundle and suppress the tumbling.

Molaei, Mehdi; Sheng, Jian

2011-11-01

118

Electron Paramagnetic Resonance Studies of Slowly Tumbling Vanadyl Spin Probes in Nematic Liquid Crystals.  

National Technical Information Service (NTIS)

An analysis of EPR line shapes by the method of Polnaszek, Bruno, and Freed is made for slowly tumbling vanadyl spin probes in viscous nematic liquid crystals. The use of typical vanadyl complexes as spin probes for nematic liquid crystals is shown to sim...

G. V. Bruno J. K. Harrington M. P. Eastman

1978-01-01

119

The effects of RN genotype and tumbling on processing yield in cured–smoked pork loins  

Microsoft Academic Search

The objective was to investigate the effects of RN genotype and tumbling treatment on yields throughout the processing of cured–smoked loins. Furthermore, the economic outcome was calculated for the different treatments because the technological yield is important for the meat industry. The study comprised two separate trials, T1 and T2, and included loins from 62 and 32 female pigs crossbreed

Anja Hullberg; Kerstin Lundström

2004-01-01

120

A phenomenological model for perforation of moderately thick plates by tumbling projectiles  

Microsoft Academic Search

A phenomenological model has been developed to describe the mechanism of tumbling perforation of blunt-faced cylindrical projectiles in moderately thick aluminum plates. The perforation process, based on experimental observations, consists of four stages: erosion; plugging; hole enlargement and petaling. The modeling in the plugging stage consists sequentially of cratering, plug formation, plug separation, plug slipping and post perforation deformation. Bulging

Kezhun Li; Werner Goldsmith

1996-01-01

121

An analytical model for tumbling projectile perforation of thin aluminum plates  

Microsoft Academic Search

An analytical model for the perforation of thin aluminum targets by tumbling cylindrical projectiles was developed. The target material was considered to be rigid—perfectly plastic without strain hardening, while the projectile was treated as undeformable. The perforation process was experimentally found to consist of three stages: plugging, hole enlargement, and front petaling. Both conservation of energy and conservation of momentum

Kezhun Li; Werner Goldsmith

1996-01-01

122

Effects of rigor state and tumbling time on quality of goat hams  

Microsoft Academic Search

Twelve West African Dwarf goat were slaughtered in this study. The animals were slaughtered in groups of three. The meat from each of the two hind legs from the goat was assigned to either pre- or post-rigor treatment. The main groups (pre- vs post-rigor state) were further treated in a split plot design to study the effect of three tumbling

Tenin Dzudie; Ademola Okubanjo

1999-01-01

123

The effects of tumbling and sodium tripolyphosphate on the proteins of döner  

Microsoft Academic Search

This study was designed to investigate the influence of tumbling and sodium tripolyphosphate (STPP) with marination on the protein structure of raw and cooked döner, a traditional Middle East product consumed widely in many areas of the world. Proximate composition (%moisture, %protein, %fat, %ash, and pH value), salt soluble protein (SSP) and total ?-amino grup amount were determined. Sodium dodecyl

Eda Demirok; Nuray Kolsar?c?; ?lker Turan Ako?lu; Esma Özden

2011-01-01

124

Sensory Fusion for Planetary Surface Robotic Navigation, Rendezvous, and Manipulation Operations  

Microsoft Academic Search

The upcoming missions to Mars planned by NASMJPL in 2009 and 2013 are more ambitious than any previouslyjlown. Included in these missions are extended multi-kilometer traverses, and autonomous rover rendezvous with science targets and man-made structures such as landers. This paper reports some of the ongoing work at JPL in the areas of autonomous sensory fusion of both raw and

Terry Huntsberger; Yang Cheng; Eric T. Baumgartner; Matthew Robinson; Paul S. Schenker

125

S\\/W concept for an autonomous rendezvous and docking mission  

Microsoft Academic Search

The onboard software required for a typical rendezvous and docking mission profile is discussed. The mission profiles for the MATRA and MBB\\/ERNO satellites are given along with corresponding satellite configurations. The navigational algorithms used in the individual mission phases are briefly explained, and the corresponding structure of the application software and the related service software are addressed.

J. Sommer

1986-01-01

126

Analysis of the Relative Attitude Estimation and Control Problem for Satellite Inspection and Orbital Rendezvous  

Microsoft Academic Search

A key component of satellite inspection and orbital rendezvous missions is relative atti- tude 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 pre- selected RSO features. The pixel measurements

D. Geller

127

Optimal starting conditions for the rendezvous maneuver: Analytical and computational approach  

Microsoft Academic Search

The three-dimensional rendezvous between two spacecraft is considered: a target spacecraft on a circular orbit around the Earth and a chaser spacecraft initially on some elliptical orbit yet to be determined. The chaser spacecraft has variable mass, limited thrust, and its trajectory is governed by three controls, one determining the thrust magnitude and two determining the thrust direction. We seek

Marco Ciarcia

2008-01-01

128

Performance Capabilities of a Phase One Automatic Rendezvous and Capture System.  

National Technical Information Service (NTIS)

This paper presents an analysis of the performance of the existing 'Phase One' AR&C system developed at the C.S. Draper Laboratory for both the rendezvous and proximity operations mission phases. This material has been developed as a result of Draper Labo...

P. M. Kachmar R. J. Polutchko M. Matusky

1991-01-01

129

In-Flight Calibration of the Near Earth Asteroid Rendezvous Mission's Near Infrared Spectrometer  

Microsoft Academic Search

The Near Infrared Spectrometer (NIS) instrument on the Near Earth Asteroid Rendezvous (NEAR) spacecraft performed a comprehensive series of in-flight tests to validate its preflight radiometric characteristics and to characterize instrument stability, pointing, and co-alignment with other instruments under flight conditions. The results of these tests form the basis of the NIS data reduction and calibration procedure and will support

Noam R. Izenberg; James F. Bell; Jeffery W. Warren; Scott L. Murchie; Keith Peacock; E. Hugo Darlington; Brian Carcich; Clark Chapman; Beth E. Clark; Ann Harch; Gene Heyler; Jonathan Joseph; Patrick Martin; Lucy McFadden; Bill Merline; Mark Robinson; Joseph Veverka; Dennis Wellnitz

2000-01-01

130

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

Microsoft Academic Search

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

Stefan Berinde

2007-01-01

131

Optimum rendezvous transfer between coplanar heliocentric elliptic orbits using solar sail  

Microsoft Academic Search

A convenient formulation is presented for determining the effect of terminal orbit eccentricities on the steering profile of a sail spacecraft for time-optimal rendezvous transfer between coplanar heliocentric orbits. The problem is reduced to that of solving a two-point boundary value problem for a system of seven ordinary differential equations. The system is solved using the controlled random search optimization

P. V. S. Rao; R. V. Ramanan

1992-01-01

132

Optimal three-dimensional heliocentric solar-sail rendezvous transfer trajectories  

Microsoft Academic Search

This study is concerned with the problem of optimization of the control, in the sense of high speed of response, for minimum time rendezvous transfer of sail-spacecraft between heliocentric, inclined, elliptic orbits. The angles defining the orientation of the sail (assumed to be perfectly reflecting and flat) with respect to sunlight are the control variables. The analysis employs a two-body

P. V. Subba Rao; R. V. Ramanan

1993-01-01

133

RDMA read based rendezvous protocol for MPI over InfiniBand: design alternatives and benefits  

Microsoft Academic Search

Message Passing Interface (MPI) is a popular parallel programming model for scientific applications. Most high-performance MPI im- plementations use Rendezvous Protocol for efficient transfer of large messages. This protocol can be designed using either RDMA Write or RDMA Read. Usually, this protocol is implemented using RDMA Write. The RDMA Write based protocol requires a two- way handshake between the sending

Sayantan Sur; Hyun-wook Jin; Lei Chai; Dhabaleswar K. Panda

2006-01-01

134

Squaring, parity breaking, and S tumbling of vesicles under shear flow.  

PubMed

The numerical study of 3D vesicles with a reduced volume equal to that of human red blood cells leads to the discovery of three types of dynamics: (i) squaring motion, in which the angle between the direction of the longest distance and the flow velocity undergoes discontinuous jumps over time, (ii) spontaneous parity breaking of the shape leading to cross-streamline migration, and (iii) S tumbling where the vesicle tumbles, exhibiting a pronounced S-like shape with a waisted morphology in the center. We report on the phase diagram within a wide range of relevant parameters. Our estimates reveal that healthy and pathological red blood cells are also prone to these types of motion, which may affect blood microcirculation and impact oxygen transport. PMID:23368389

Farutin, Alexander; Misbah, Chaouqi

2012-12-10

135

Squaring, Parity Breaking, and S Tumbling of Vesicles under Shear Flow  

NASA Astrophysics Data System (ADS)

The numerical study of 3D vesicles with a reduced volume equal to that of human red blood cells leads to the discovery of three types of dynamics: (i) squaring motion, in which the angle between the direction of the longest distance and the flow velocity undergoes discontinuous jumps over time, (ii) spontaneous parity breaking of the shape leading to cross-streamline migration, and (iii) S tumbling where the vesicle tumbles, exhibiting a pronounced S-like shape with a waisted morphology in the center. We report on the phase diagram within a wide range of relevant parameters. Our estimates reveal that healthy and pathological red blood cells are also prone to these types of motion, which may affect blood microcirculation and impact oxygen transport.

Farutin, Alexander; Misbah, Chaouqi

2012-12-01

136

The effects of tumbling and sodium tripolyphosphate on the proteins of döner.  

PubMed

This study was designed to investigate the influence of tumbling and sodium tripolyphosphate (STPP) with marination on the protein structure of raw and cooked döner, a traditional Middle East product consumed widely in many areas of the world. Proximate composition (%moisture, %protein, %fat, %ash, and pH value), salt soluble protein (SSP) and total ?-amino grup amount were determined. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to investigate alterations in the sarcoplasmic and myofibrillar proteins. Utilization of STPP increased the moisture content and ash contents, and pH value of raw döner (p<0.05). Only tumbling and STPP had a significant two-way interaction for moisture content, SSP and total ?-amino group amounts of cooked döner (p<0.05). None of the treatments significantly affected the fraction of sarcoplasmic and myofibrillar proteins. In addition, cooking caused proteolysis of these proteins. PMID:21561722

Demirok, Eda; Kolsar?c?, Nuray; Ako?lu, ?lker Turan; Özden, Esma

2011-04-16

137

A molecular reel: shuttling of a rotor by tumbling of a macrocycle.  

PubMed

A molecular shuttle is a prototype of molecular machines capable of shuttling a part back and forth in the molecule. To control the shuttling of a macrocycle, we studied the reeling of an axis molecule into a macrocyclic host molecule located at the end of the axis. [2]Rotaxane and [3]rotaxane are composed of alpha-cyclodextrin (alpha-CD) rotors, a decamethylene chain, and a stilbene unit as axes and an altro-alpha-CD stopper containing one altropyranose unit and five glucopyranose units. The alpha-CD rotor of [2]rotaxane includes the decamethylene chain in DMSO-d(6) and moves to include the stilbene group in D(2)O. It should be noted that the altro-alpha-CD stopper group reorients to include the decamethylene chain in D(2)O. The mechanism for tumbling was elucidated with 2D ROESY NMR measurements and kinetic studies. These studies showed that an altropyranose unit of the altro-alpha-CD stopper tumbles to form a self-inclusion complex in aqueous solution. The altro-alpha-CD stopper of [2]rotaxane reels an axis molecule into its cavity and then pushes the alpha-CD rotor onto the stilbene group, resulting in conversion to pseudo[2]rotaxane in D(2)O. In contrast, the rotors of [3]rotaxane did not show shuttling because there was insufficient space not only for the rotors to shuttle but also for the altro-alpha-CD stopper to include an axis after tumbling. The decamethylene chain and the stilbene group are already included in the rotors of [3]rotaxane. The tumbling of the altro-alpha-CD stopper was found to play a critical role in controlling the shuttling of rotors. We successfully controlled the shuttling of a rotor by reeling the axis molecule into a host molecule at the end of an axis. PMID:20073513

Yamauchi, Kazuhiro; Miyawaki, Atsuhisa; Takashima, Yoshinori; Yamaguchi, Hiroyasu; Harada, Akira

2010-02-19

138

Simulation of the flow field and tumbling dynamics of multiply flagellated bacterium  

NASA Astrophysics Data System (ADS)

To study the hydrodynamics of swimming of multi-flagellated bacteria, such as Escherichia coli, we develop a simulation method using a bead-spring model to account for the hydrodynamic and the mechanical interactions between multiple flagella and the cell body, the reversal of the rotation of a flagellum in a tumble and associated polymorphic transformations of the flagellum. This simulation reproduces the experimentally observed behaviors of E. coli, namely, a three-dimensional random-walk trajectory in run-and-tumble motion and steady clockwise swimming near a wall. Here we show using a modeled cell that the polymorphic transformation of flagellum in a tumble facilitates the reorientation of the cell, and that the time-averaged flow field near a cell in a run has double-layered helical streamlines. Moreover, the instantaneous flow field, which is strongly time-dependent, is more than 10-fold larger in magnitude than the time-averaged flow, large enough to affect the migration behavior of surrounding chemoattractants, with the Peclet number for these molecules being larger than one near a swimming cell.

Larson, Ronald; Watari, Nobuhiko

2009-11-01

139

Safety strategy and implementation for the rendezvous of the Columbus Free-Flyer with the Space Station Freedom  

NASA Astrophysics Data System (ADS)

The mission of the Columbus Free Flyer includes active rendezvous maneuvers with the International Space Station Freedom. This imposes challenging safety requirements, which drive the design of the autonomous GNC (Guidance, Navigation, and Control) subsystem. The rendezvous safety philosophy is based on the safe trajectory principle. This means that, at any point in time, propulsion shutoff will lead to a free drift trajectory that does not intersect the flight path of Space Station Freedom. This concept allows a separation of nominal flight control functions from those functions required for safety check and abort of the rendezvous. The rendezvous scenario and the safety related requirements are reviewed and the proposed safety strategy and its hardware and software implementation in the GNC of the Columbus Free Flyer are shown.

Kolkmeier, Arnd; Schnetzer, Wolfgang

1991-12-01

140

von Braun and the lunar-orbit rendezvous decision: finding a way to go to the moon  

Microsoft Academic Search

Wernher von Braun's historic talk at Huntsville on June 7, 1962, when he endorsed “lunar-orbit rendezvous” (LOR) as the mode for landing on the Moon, has long been seen as one of the most critical dates in the Apollo program. It effectively ended a months-long, divisive debate inside NASA over LOR versus “earth-orbit rendezvous” (EOR) versus “direct ascent” (a single

Michael J. Neufeld

2008-01-01

141

The effects of low salt concentrations on the mechanism of adhesion between two pieces of pork semimembranosus muscle following tumbling and cooking.  

PubMed

The aim of this research was to gain deeper insight into the effect of salt content on the adhesion between pieces of semimembranosus pork muscle bound by a tumbling exudate gel. Hydrophobic site number, free thiol and carbonyl content were measured in tumbling exudate and meat protein to evaluate the protein-protein interactions involved in the adhesion process. Proteins were far more oxidized in exudate than in meat, and under our experimental conditions, salt content increased protein bonding in the exudate but not in the meat. Breaking stress increased between non-salted meat and 0.8%-salted meat but did not depend on the protein physicochemical properties of the tumbling exudate. Modifying the meat surface by tumbling alone, tumbling and salting, or scarification had no effect on breaking stress. It is suggested that the break between the meat pieces occurred between the tumbling exudate and the meat surface due to weaker chemical bonds at this location. PMID:23896131

Bombrun, Laure; Gatellier, Philippe; Carlier, Martine; Kondjoyan, Alain

2013-07-04

142

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

143

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

144

Trajectory design for an ion drive asteroids rendezvous mission launched into an Ariane geostationary transfer orbit  

NASA Astrophysics Data System (ADS)

AMSAT has conceived an asteroid rendezvous mission which would consist of an Ariane-launched, 3-axis-stabilized, 350-kg spacecraft utilizing both mercury and solar electric ion propulsion. The spacecraft is to be equipped with a science instrument platform with a mass of approximately 30 to 50 kg. Practically uninterrupted earth departure opportunities are found for targets such as 4 Vesta, 8 Flora, and 19 Fortuna from 1986 through 1988. The 7 to 8 year mission would allow for a second rendezvous of 4 Vesta, and marginal additional fuel would make close flybys of targets feasible. Through the use of parameter optimization techniques, trajectories can be generated and the inclusion of constraints due to spacecraft techology, tour design, and navigation can be facilitated.

Pietrass, A. E.

1984-08-01

145

An approximate analytical method for short-range impulsive orbit rendezvous using relative Lambert solutions  

NASA Astrophysics Data System (ADS)

A new approximate analytical method for the two-body impulsive orbit rendezvous problem with short range is presented. The classical analytical approach derives the initial relative velocity from the state transition matrix of linear relative motion equations. This paper proposes a different analytical approach based on the relative Lambert solutions. An approximate expression for the transfer time is obtained as a function of chaser's and target's semi-major axes difference. This results in first and second order estimates of the chaser's semi-major axis. Singularity points of rendezvous time for the classical and proposed new methods are both analyzed. As compared with the classical method, the new solution is simpler, more accurate, and has fewer singularity points. Moreover, the proposed method can be easily expanded to higher order solutions. A numerical example quantifies the accuracy gain for multiple-revolution cases.

Zhang, Gang; Zhou, Di; Mortari, Daniele

2012-12-01

146

Interception, evasion, rendezvous and velocity-to-be-gained guidance for spacecraft  

NASA Astrophysics Data System (ADS)

Optimal nonlinear feedback guidance laws are derived for a pursuit-evasion differential game between two spacecraft, and for more traditional problems of spacecraft rendezvous and velocity-to-be-gained tasks. The present approach uses complete nonlinear point-mass models for spacecraft and is suitable for on-board implementation. The guidance laws are applicable for large amplitude maneuvers and can account for the presence of more than one gravitational field.

Menon, P. K. A.; Calise, A. J.

147

Two-impulse minimum-time earth launch-to-rendezvous trajectories  

Microsoft Academic Search

This paper presents an analysis of minimum-time two-impulse ascent trajectories for a single-stage rocket between launch from the earth and rendezvous with a satellite in a circular orbit around the earth. First the minimum-time trajectories from earth launch to injection into a circular orbit are investigated. These results are then combined with the motion of the target satellite during the

G. M. Anderson; S. H. Edelman

1974-01-01

148

Short range and proximity sensor for autonomous rendez-vous and docking  

NASA Astrophysics Data System (ADS)

Rendezvous and docking (RVD) sensors have currently been the subject of investigation on the part of MATRA and SODERN. The paper presents the 'future flight sensor' together with estimates of accuracy, mass, power, and reliability. The imager sensor for the short range and proximity phases of RVD appears to be the most suitable and promising in terms of performance capability. Moreover, this concept conforms to the present-day Columbus and Hermes specifications.

Flamenbaum, S.; Bomer, T.; Jamet, J.; Turon, P.; Krebs, J. P.

1986-10-01

149

Deterministic Rendezvous of Asynchronous Bounded-Memory Agents in Polygonal Terrains  

NASA Astrophysics Data System (ADS)

Two mobile agents, modeled as points starting at different locations of an unknown terrain, have to meet. The terrain is a polygon with polygonal holes. We consider two versions of this rendezvous problem: exact RV, when the points representing the agents have to coincide at some time, and ?-RV, when these points have to get at distance less than ? in the terrain. In any terrain, each agent chooses its trajectory, but the movements of the agent on this trajectory are controlled by an adversary that may, e.g., speed up or slow down the agent. Agents have bounded memory: their computational power is that of finite state machines. Our aim is to compare the feasibility of exact and of ?-RV when agents are anonymous vs. when they are labeled. We show classes of polygonal terrains which distinguish all the studied scenarios from the point of view of feasibility of rendezvous. The features which influence the feasibility of rendezvous include symmetries present in the terrains, boundedness of their diameter, and the number of vertices of polygons in the terrains.

Czyzowicz, Jurek; Kosowski, Adrian; Pelc, Andrzej

150

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

2007-05-01

151

Rough-and-Tumble Play and the Regulation of Aggression: An Observational Study of Father-Child Play Dyads  

PubMed Central

Rough-and-tumble play (RTP) is a common form of play between fathers and children. It has been suggested that RTP can contribute to the development of selfregulation. This study addressed the hypothesis that the frequency of father–child RTP is related to the frequency of physically aggressive behavior in early childhood. This relationship was expected to be moderated by the dominance relationship between father and son during play. Eighty-five children between the ages of 2 and 6 years were videotaped during a free-play session with their fathers in their homes and questionnaire data was collected about father–child RTP frequency during the past year. The play dyads were rated for the degree to which the father dominated play interactions. A significant statistical interaction revealed that RTP frequency was associated with higher levels of physical aggression in children whose fathers were less dominant. These results indicate that RTP is indeed related to physical aggression, though this relationship is moderated by the degree to which the father is a dominant playmate.

Flanders, Joseph L.; Leo, Vanessa; Paquette, Daniel; Pihl, Robert O.; Seguin, Jean R.

2012-01-01

152

Run and tumble, run and reverse, or run reverse and flick - who wins the chemotaxis race?  

NASA Astrophysics Data System (ADS)

Run and tumble of E.coli bacteria is a well understood example of the stochastic cell motion that is alternated in the presence of signaling chemicals. By regulating the tumbling frequency bacteria are able to navigate toward the food sources. Another bacteria that use twitching to move on a surface, M. xanthus, utilize a different strategy - at the end of the run they completely reverse the direction of motion and continue moving in the opposite direction. The frequency of reversals was shown to be connected to the chemotactic response of the cell. Recently yet another pattern was discovered in marine bacteria V. alginolyticus which alternate sharp reversals with flicks -- making a turn to an angle with a broad distribution and centered around 90 degrees. In this work we are presenting a theoretical framework that describes all above motion patterns. As a highlight of the developed approach we find the exact analytical expressions for the mean squared displacement of moving cells for arbitrary distribution of run times. That allows us to quantitatively compare the performance of bacteria exploring the environment with and without signaling chemicals and, therefore, to find the winner of the chemotactic race.

Zaburdaev, Vasily; Denisov, Sergey; Weitz, David

2012-02-01

153

Application of model predictive heuristic control to automatic rendezvous of spacecraft  

NASA Astrophysics Data System (ADS)

The Principle of Model Predictive Heuristic Control (PMHC) technique is applied here to automatic spacecraft rendezvous using a new, real-time algorithm for the linear least squares solution of MIMO systems. In contrast to the approach of Emara-Shabaik (1981), the predictive feature is obviously present. The design of the closed-loop system is advantageous compared to that of Emara-Shabaik in that it decreases the amplitude of the maximum engine thrust and increases the flexibility in designing the prediction horizon, smoothing points, control switching time, and weighting matrix. Numerical simulation results show improved system performance, decreased total fuel consumption, and satisfactory robustness to external disturbances.

Zhu, Ziqian; Jiang, Yunxiang

1990-07-01

154

Translocation and thermal inactivation of Shiga toxin-producting Escherichia coli in blade tenderized and/or vacuum tumbled beef  

Technology Transfer Automated Retrieval System (TEKTRAN)

Foodborne pathogens, such as Shiga toxin-producing Escherichia coli (STEC), a natural inhabitant on raw meat, may be transferred from the surface of the meat into the deeper layers of tissue following enhancement by blade tenderization and vacuum tumbling. Therefore, the consumption of enhanced beef...

155

Monsters, Magic and Mr Psycho: A Biocultural Approach to Rough and Tumble Play in the Early Years of Primary School  

ERIC Educational Resources Information Center

|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…

Jarvis, Pam

2007-01-01

156

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

157

Slow tumbling but large protrusion of phospholipids in the cell sized giant vesicle  

NASA Astrophysics Data System (ADS)

Lipid membrane dynamics in cell sized vesicles (CSVs) in water is characterized by the solution-state NMR. CSV is successfully prepared by natural swelling method using osmotic effect. Broad 1H NMR signal and large 31P NMR chemical shift anisotropy show the slow tumbling of the lipid with the rotational correlation time 0.2-2.8 s in CSV of 10-20 ?m-diameters. The 1H-1H nuclear Overhauser effect enhancement reveals the proximity between the lipid headgroup and alkyl chains, in which the close distance, ˜0.4 nm. The proximity is due to the large protrusion of the lipids in the vertical direction to the CSV surface.

Takechi, Yuki; Saito, Hiroyuki; Okamura, Emiko

2013-05-01

158

Randomly curved runs interrupted by tumbling: A model for bacterial motion  

NASA Astrophysics Data System (ADS)

Small bacteria are strongly buffeted by Brownian forces that make completely straight runs impossible. A model for bacterial motion is formulated in which the effects of fluctuational forces and torques on the run phase are taken into account by using coupled Langevin equations. An integrated description of the motion, including runs and tumbles, is then obtained by the use of convolution and Laplace transforms. The properties of the velocity-velocity correlation function, of the mean displacement, and of the two relevant diffusion coefficients are examined in terms of the bacterial sizes and of the magnitude of the propelling forces. For bacteria smaller than E. coli, the integrated diffusion coefficient crosses over from a jump-dominated to a rotational-diffusion-dominated form.

Condat, C. A.; Jäckle, J.; Menchón, S. A.

2005-08-01

159

Morphology of fast-tumbling bicelles: a small angle neutron scattering and NMR study.  

PubMed

Bilayered micelles, or bicelles, which consist of a mixture of long- and short-chain phospholipids, are a popular model membrane system. Depending on composition, concentration, and temperature, bicelle mixtures may adopt an isotropic phase or form an aligned phase in magnetic fields. Well-resolved (1)H NMR spectra are observed in the isotropic or so-called fast-tumbling bicelle phase, over the range of temperatures investigated (10-40 degrees C), for molar ratios of long-chain lipid to short-chain lipid between 0.20 and 1.0. Small angle neutron scattering data of this phase are consistent with the model in which bicelles were proposed to be disk-shaped. The experimentally determined dimensions are roughly consistent with the predictions of R.R. Vold and R.S. Prosser (J. Magn. Reson. B 113 (1996)). Differential paramagnetic shifts of head group resonances of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC), induced by the addition of Eu(3+), are also consistent with the bicelle model in which DHPC is believed to be primarily sequestered to bicelle rims. Selective irradiation of the DHPC aliphatic methyl resonances results in no detectable magnetization transfer to the corresponding DMPC methyl resonances (and vice versa) in bicelles, which also suggests that DHPC and DMPC are largely sequestered in the bicelle. Finally, (1)H spectra of the antibacterial peptide indolicidin (ILPWKWPWWPWRR-NH(2)) are compared, in a DPC micellar phase and the above fast-tumbling bicellar phases for a variety of compositions. The spectra exhibit adequate resolution and improved dispersion of amide and aromatic resonances in certain bicelle mixtures. PMID:11470082

Luchette, P A; Vetman, T N; Prosser, R S; Hancock, R E; Nieh, M P; Glinka, C J; Krueger, S; Katsaras, J

2001-08-01

160

Extended-mission opportunities for a Discovery-class asteroid rendezvous mission  

NASA Astrophysics Data System (ADS)

The nominal target for NASA's proposed Near-Earth Asteroid Rendezvous (NEAR) mission is a small object called 4660 Nereus (formerly known as 1982 DB). A Delta-7925 rocket will be used to launch the NEAR spacecraft towards this body in January 1998. On its way to Nereus, NEAR will perform a flyby of the main-belt asteroid, 2019 Van Albada. The rendezvous phase at Nereus will begin in January 2000. It is planned to initiate an extended-mission phase on September 12, 2000. On this date, a small propulsive maneuver will be used to retarget NEAR for an Earth encounter in February 2002. Different combinations of Earth-swingby and propulsive maneuvers can then be used to redirect the NEAR spacecraft to a variety of asteroids and comets. Possible targets include Encke's comet, the large near-Earth asteroids, 433 Eros and 1036 Ganymed, a prominent main-belt asteroid, 4 Vesta, and a defunct comet nucleus, 4015 (1979 VA). The majority of the extended-mission scenarios presented here contain multiple-encounter sequences. In one plan, called the Small-Body Grand Tour, flybys of two comets and two asteroids are achieved over a 10-year period.

Farquhar, Robert; Jen, Shao-Chiang; McAdams, Jim V.

161

In-Flight Calibration of the Near Earth Asteroid Rendezvous Laser Rangefinder  

NASA Astrophysics Data System (ADS)

The Near Earth Asteroid Rendezvous (NEAR) mission began a year-long rendezvous with 433 Eros on 14 February 2000. The NEAR Laser Rangefinder (NLR) will measure ranges from the spacecraft to the surface of Eros with a single shot accuracy of a few meters. The NLR topographic data, when combined with doppler tracking of the spacecraft, will enable determinations of the asteroid's shape, mass, and density and will contribute to understanding of its internal structure and collisional evolution. NLR is the first space-borne laser altimeter with an in-flight calibration capability, achieved by means of an optical fiber which directs a small portion of every outgoing laser pulse back to the receiver with a known, fixed time delay. Key results of groundbased and in-flight calibrations of NLR are presented for: in-flight measurement of receiver noise statistics, confirmation of instrument stability over the 4-year cruise to Eros, absolute calibration of range measurements for ideal targets (flat, uniform surfaces normal to the boresight), and a prediction of single-pulse detection probability and range errors in the presence of pulse dilation from nonideal target surfaces, based on a Webb's approximation model of receiver performance. We find that pulse dilation is the major source of uncertainty in the single-shot range measurements from NLR, and that this uncertainty is consistent with the 6-m range measurement requirement for NEAR.

Cheng, Andrew F.; Cole, Timothy D.; Zuber, Maria T.; Smith, David E.; Guo, Yanping; Davidson, Frederic

2000-12-01

162

Control of a space robot for minimal attitude disturbance to the base satellite for capturing a tumbling satellite  

NASA Astrophysics Data System (ADS)

The use of a space manipulator (robot) for capturing a tumbling object is a risky and challenging task, mainly because when the manipulator onboard a servicing satellite (base satellite) intercepts with an external object for capture, the resulting impulse will be transferred along the mechanical arm down to the servicing satellite causing disturbance to the attitude of the satellite. Such disturbance may destabilize the servicing satellite if the captured object is tumbling and the physical contact between the robot end-effector and the object is not controlled properly. Certainly, the risk may be mitigated with a force or impedance control capability of the manipulator. However, the implementation of force or impedance control usually requires the robot to have a joint torque sensing and control capability which is a very expensive requirement for a space manipulator. To date, there has never been a really flown space manipulator having a joint torque control capability. Further, even a force or impedance control capability becomes available, much development is still needed before safe capture of a tumbling object can be confidently tried in a real mission. This paper presents an optimal control strategy for a space manipulator to have minimal impact to the base satellite during a capturing operation. The idea is to first predict an optimal future time and motion state for capturing and then control the manipulator to reach the determined motion state such that, when the tip of the robot maneuvers to and intercepts with the tumbling object, a minimal attitude disturbance to the servicing satellite will occur. The proposed control strategy can be implemented regardless whether the manipulator has a joint torque control capability or not. Since the control acts before a physical contact happens, it will not affect but actually augment any existing force or impedance control capability of the manipulator. The proposed method is demonstrated using a simulation example.

Flores-Abad, Angel; Ma, Ou

2012-05-01

163

Orbit determination for the Mariner Mark II Comet Rendezvous/Asteroid Flyby mission - The orbiting phase  

NASA Astrophysics Data System (ADS)

The Comet Rendezvous/Asteroid Flyby (CRAF) mission is the first of the Mariner Mark II mission set, designed to explore the outer solar system. Major objectives of orbit determination will be determine the positions and masses of the comet and asteroid and the relative position of the spacecraft, which is important to accurate pointing of the scan platform on which the narrow angle camera and scientific instruments are positioned. Position prediction is also important, since continuous commuication with the spacecraft will not be possible. The small gravitational attractions and poorly known ephemerides of the comet and asteroid, and the small, slow spacecraft orbit about the comet, pose significant new problems for orbit determination. Results of simulations studying the effectiveness of key data types, the accuracies of estimates, and prediction capabilities, are presented.

Weeks, C. J.

1986-08-01

164

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

NASA Astrophysics Data System (ADS)

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 the Trojans' formation at large solar distances. Based on DAWN and other comparable missions, we have determined suitable payload instruments to achieve these objectives. Afterwards, we have designed a spacecraft that is able to carry the selected payload to the Trojan region and rendezvous successively with three target bodies within a maximum mission duration of 15 years. Accurate low-thrust trajectories have been obtained with a global low-thrust trajectory optimization program (InTrance). During the transfer from Earth to the first target, the spacecraft is propelled by two RIT-22 ion engines from EADS Astrium, whereas a single RIT-15 is used for transfers within the Trojan region to reduce the required power. For power generation, the spacecraft uses a multi-junction solar array that is supported by concentrators. To achieve moderate mission costs, we have restricted the launch mass to a maximum of 1600 kg, the maximum interplanetary injection capability of a Soyuz/Fregat launcher. Our final layout has a mass of 1400 kg, yielding a margin of about 14%. Nestor (a member of the L4-population) was determined as the first mission target. It can be reached within 4.6 years from launch. The fuel mass ratio for this transfer is about 35%. The stay time at Nestor is 1.2 years. Eurymedon was selected as the second target (transfer time 3.5 years, stay time 3.0 years) and Irus as the third target (transfer time 2.2 years). The transfers within the Trojan L4-population can be accomplished with fuel mass ratios of about 3% for each trajectory leg. Including the stay times in orbit around the targets, the mission can be accomplished within a total duration of about 14.5 years. According to our mission analysis, it is also feasible to fly to the L5-population with similar flight times. It has to be noted that -for a first analysis -we have taken only the named targets into account. Allowing also rendezvous with unnamed objects will very likely decrease the mission duration. Based on a scaling of DAWN's mission costs (due to comparable scientific instruments and mission objectives), and taking into account the longer mission duration and the potential re-use of already developed technology, we have estimated that these three rendezvous can be accomplished with a budget of about 250 Million Euros, i.e. about 25% of ROSETTA's budget.

Maiwald, Volker; Dachwald, Bernd

165

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

NASA Astrophysics Data System (ADS)

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

166

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

167

Multiple spacecraft rendezvous maneuvers by differential drag and low thrust engines  

NASA Astrophysics Data System (ADS)

A novel two-phase hybrid controller is proposed to optimize propellant consumption during multiple spacecraft rendezvous maneuvers in Low Earth Orbit. This controller exploits generated differentials in aerodynamic drag on each involved chaser spacecraft to effect a propellant-free trajectory near to the target spacecraft during the first phase of the maneuver, and then uses a fuel optimal control strategy via continuous low-thrust engines to effect a precision dock during the second phase. In particular, by varying the imparted aerodynamic drag force on each of the chaser spacecraft, relative differential accelerations are generated between each chaser and the target spacecraft along two of the three translational degrees of freedom. In order to generate this required differential, each chaser spacecraft is assumed to include a system of rotating flat panels. Additionally, each chaser spacecraft is assumed to have continuous low-thrust capability along the three translational degrees of freedom and full-axis attitude control. Sample simulations are presented to support the validity and robustness of the proposed hybrid controller to variations in the atmospheric density along with different spacecraft masses and ballistic coefficients. Furthermore, the proposed hybrid controller is validated against a complete nonlinear orbital model to include relative navigation errors typical of carrier-phase differential GPS (CDGPS). Limitations of the proposed controller appear relative to the target spacecraft's orbit eccentricity and a general characterization of the atmospheric density. Bounds on these variables are included to provide a framework within which the proposed hybrid controller can effect an extremely low propellant rendezvous of multiple chaser spacecraft to a desired target spacecraft.

Bevilacqua, Riccardo; Hall, Jason S.; Romano, Marcello

2010-01-01

168

Assessing the Size, Stability, and Utility of Isotropically Tumbling Bicelle Systems for Structural Biology  

PubMed Central

Aqueous phospholipid mixtures that form bilayered micelles (bicelles) have gained wide use by molecular biophysicists during the past 20 years for spectroscopic studies of membrane-bound peptides and structural refinement of soluble protein structures. Nonetheless, the utility of bicelle systems may be compromised by considerations of cost, chemical stability, and preservation of the bicelle aggregate organization under a broad range of temperature, concentration, pH, and ionic strength conditions. In the current work, 31P nuclear magnetic resonance (NMR) and atomic force microscopy (AFM) have been used to monitor the size and morphology of isotropically tumbling small bicelles formed by mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1,2-di-O-tetradecyl-sn-glycero-3-phosphocholine (DIOMPC) with either 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) or 1,2-di-O-hexyl-sn-glycero-3-phospho-choline (DIOHPC), testing their tolerance of variations in commonly used experimental conditions. 1H-15N 2D NMR has been used to demonstrate the usefulness of the robust DMPC-DIOHPC system for conformational studies of a fatty acid-binding protein that shuttles small ligands to and from biological membranes.

Wu, Hongwei; Su, Kai; Guan, Xudong; Sublette, M. Elizabeth; Stark, Ruth E.

2009-01-01

169

Drill Holes and Predation Traces versus Abrasion-Induced Artifacts Revealed by Tumbling Experiments  

PubMed Central

Drill holes made by predators in prey shells are widely considered to be the most unambiguous bodies of evidence of predator-prey interactions in the fossil record. However, recognition of traces of predatory origin from those formed by abiotic factors still waits for a rigorous evaluation as a prerequisite to ascertain predation intensity through geologic time and to test macroevolutionary patterns. New experimental data from tumbling various extant shells demonstrate that abrasion may leave holes strongly resembling the traces produced by drilling predators. They typically represent singular, circular to oval penetrations perpendicular to the shell surface. These data provide an alternative explanation to the drilling predation hypothesis for the origin of holes recorded in fossil shells. Although various non-morphological criteria (evaluation of holes for non-random distribution) and morphometric studies (quantification of the drill hole shape) have been employed to separate biological from abiotic traces, these are probably insufficient to exclude abrasion artifacts, consequently leading to overestimate predation intensity. As a result, from now on, we must adopt more rigorous criteria to appropriately distinguish abrasion artifacts from drill holes, such as microstructural identification of micro-rasping traces.

Gorzelak, Przemyslaw; Salamon, Mariusz A.; Trzesiok, Dawid; Niedzwiedzki, Robert

2013-01-01

170

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

Microsoft Academic Search

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

Anny-Chantal Levasseur-Regourd

2008-01-01

171

3D kinematic and dynamic analysis of the front crawl tumble turn in elite male swimmers.  

PubMed

The aim of this study was to identify kinematic and dynamic variables related to the best tumble turn times (3mRTT, the turn time from 3-m in to 3-m out, independent variable) in ten elite male swimmers using a three-dimensional (3D) underwater analysis protocol and the Lasso (least absolute shrinkage and selection operator) as statistical method. For each swimmer, the best-time turn was analyzed with five stationary and synchronized underwater cameras. The 3D reconstruction was performed using the Direct Linear Transformation algorithm. An underwater piezoelectric 3D force platform completed the set-up to compute dynamic variables. Data were smoothed by the Savitzky-Golay filtering method. Three variables were considered relevant in the best Lasso model (3mRTT=2.58-0.425 RD+0.204 VPe+0.0046 TD): the head-wall distance where rotation starts (RD), the horizontal speed at the force peak (VPe), and the 3D length of the path covered during the turn (TD). Furthermore, bivariate analysis showed that upper body (CUBei) and lower limb extension indexes at first contact (CLLei) were also linked to the turn time (r=-0.65 and p<0.05 for both variables). Thus the best turn times were associated with a long RD, slower VPe and reduced TD. By an early transverse rotation, male elite swimmers reach the wall with a slightly flexed posture that results in fast extension. These swimmers opt for a movement that is oriented forward and they focus on reducing the distance covered. PMID:22176710

Puel, F; Morlier, J; Avalos, M; Mesnard, M; Cid, M; Hellard, P

2011-12-15

172

Encapsulated guest-host dynamics: guest rotational barriers and tumbling as a probe of host interior cavity space.  

PubMed

The supramolecular host assembly [Ga(4)L(6)](12-) (1; L = 1,5-bis[2,3-dihydroxybenzamido]naphthalene) encapsulates cationic guest molecules within its hydrophobic cavity and catalyzes a variety of chemical transformations within its confined interior space. Despite the well-defined structure, the host ligand framework and interior cavity are very flexible and 1 can accommodate a wide range of guest shapes and sizes. These observations raise questions about the steric effects of confinement within 1 and how encapsulation fundamentally changes the motions of guest molecules. Here we examine the motional dynamics (guest bond rotation and tumbling) of encapsulated guest molecules to probe the steric consequences of encapsulation within host 1. Encapsulation is found to increase the Ph-CH(2) bond rotational barrier for ortho-substituted benzyl phosphonium guest molecules by 3 to 6 kcal/mol, and the barrier is found to depend on both guest size and shape. The tumbling dynamics of guests encapsulated in 1 were also investigated, and here it was found that longer, more prolate-shaped guest molecules tumble more slowly in the host cavity than larger but more spherical guest molecules. The prolate guests reduce the host symmetry from T to C(1) in solution at low temperatures, and the distortion of the host framework that is in part responsible for this symmetry reduction is observed directly in the solid state. Analysis of guest motional dynamics is a powerful method for interrogating host structure and fundamental host-guest interactions. PMID:20977233

Mugridge, Jeffrey S; Szigethy, Géza; Bergman, Robert G; Raymond, Kenneth N

2010-10-26

173

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

174

Radio science results during the NEAR-shoemaker spacecraft rendezvous with eros  

PubMed

We determined the mass of asteroid 433 Eros, its lower order gravitational harmonics, and rotation state, using ground-based Doppler and range tracking of the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker spacecraft and images of the asteroid's surface landmarks. The mass of Eros is (6.687 +/- 0.003) x 10(18) grams, which, coupled with our volume estimate, implies a bulk density of 2. 67 +/- 0.03 grams per cubic centimeter. The asteroid appears to have a uniform density distribution. The right ascension and declination of the rotation pole are 11.37 +/- 0.05 and 17.22 +/- 0.05 degrees, respectively, and at least over the short term, the rotation state of Eros is stable with no measurable free precession of the spin pole. Escape velocities on the surface vary from 3.1 to 17.2 meters per second. The dynamical environment of Eros suggests that it is covered with regolith and that one might expect material transport toward the deepest potential wells in the saddle and 5.5-kilometer crater regions. PMID:11000104

Yeomans; Antreasian; Barriot; Chesley; Dunham; Farquhar; Giorgini; Helfrich; Konopliv; McAdams; Miller; Owen; Scheeres; Thomas; Veverka; Williams

2000-09-22

175

The applications of laser tracking and ranging technology in space rendezvous and docking  

NASA Astrophysics Data System (ADS)

With the development of space technology, more and more Rendezvous and Docking (RVD) mission require more precise measurement of relative position and attitude between tracking spacecraft and target spacecraft. In the procedure of docking between near spacecraft , the optical retroreflector on the target Spacecraft were tracked by the laser tracking and ranging device on the tracking spacecraft , the distance data were provided by laser ranging system, and the azimuth data were provided by tracking gimbal, Synthesized the distance data and azimuth data, the relative position information between two spacecraft were provided to the target spacecraft. Furthermore, through tracking more than three point on the target spacecraft ,the complete information of relative position and attitude between two spacecraft were calculated rapidly by the measurement system?which were presented to the control system during the whole RVD operating stage. The laser tracking technology guaranteed continuous measurement and supplied accurate azimuth information, and the laser ranging technology ensured high accuracy of distance information. In addition, the untouched measure mode give no disturbance to the docking operation, moreover, the monochromaticity of laser make the tracking and ranging procedure avoiding to be disturbed by parasitic light of space, thus there will be a effective measurement accompanying the whole docking operating procedure and affording valid data to the control system of docking.

She, Wenji; Gao, Limin; Zhou, Liang; Li, Dawei; Wang, Rong

2013-09-01

176

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

177

A new way in intelligent recognition improves control accuracy and efficiency for spacecrafts' rendezvous and docking  

NASA Astrophysics Data System (ADS)

Spacecrafts rendezvous and docking (RVD) by human or autonomous control is a complicated and difficult problem especially in the final approach stage. Present control methods have their key technology weakness. It is a necessary, important and difficult step for RVD through human's aiming chaser spacecraft at target spacecraft in a coaxial line by a three-dimension bulge cross target. At present, there is no technology to quantify the alignment in image recognition direction. We present a new practical autonomous method to improve the accuracy and efficiency of RVD control by adding image recognition algorithm instead of human aiming and control. Target spacecraft has a bulge cross target which is designed for chaser spacecraft's aiming accurately and have two center points, one is a plate surface center point(PSCP), another is a bulge cross center point(BCCP), while chaser spacecraft has a monitoring ruler cross center point(RCCP) of the video telescope optical system for aiming . If the three center points are coincident at the monitoring image, the two spacecrafts keep aligning which is suitable for closing to docking. Using the trace spacecraft's video telescope optical system to acquire the real-time monitoring image of the target spacecraft's bulge cross target. Appling image processing and intelligent recognition algorithm to get rid of interference source to compute the three center points' coordinate and exact digital offset of two spacecrafts' relative position and attitude real-timely, which is used to control the chaser spacecraft pneumatic driving system to change the spacecraft attitude in six direction: up, down, front, back, left, right, pitch, drift and roll precisely. This way is also practical and economical because it needs not adding any hardware, only adding the real-time image recognition software into spacecrafts' present video system. It is suitable for autonomous control and human control.

Wang, JiaQing; Lu, Yaodong; Wang, JiaFa

2013-08-01

178

Proximity Operations for Space Situational Awareness Spacecraft Rendezvous and Maneuvering using Numerical Simulations and Fuzzy Logic  

NASA Astrophysics Data System (ADS)

The authors present several spacecraft rendezvous and close proximity maneuvering techniques modeled with a high-precision numerical integrator using full force models and closed loop control with a Fuzzy Logic intelligent controller to command the engines. The authors document and compare the maneuvers, fuel use, and other parameters. This paper presents an innovative application of an existing capability to design, simulate and analyze proximity maneuvers; already in use for operational satellites performing other maneuvers. The system has been extended to demonstrate the capability to develop closed loop control laws to maneuver spacecraft in close proximity to another, including stand-off, docking, lunar landing and other operations applicable to space situational awareness, space based surveillance, and operational satellite modeling. The fully integrated end-to-end trajectory ephemerides are available from the authors in electronic ASCII text by request. The benefits of this system include: A realistic physics-based simulation for the development and validation of control laws A collaborative engineering environment for the design, development and tuning of spacecraft law parameters, sizing actuators (i.e., rocket engines), and sensor suite selection. An accurate simulation and visualization to communicate the complexity, criticality, and risk of spacecraft operations. A precise mathematical environment for research and development of future spacecraft maneuvering engineering tasks, operational planning and forensic analysis. A closed loop, knowledge-based control example for proximity operations. This proximity operations modeling and simulation environment will provide a valuable adjunct to programs in military space control, space situational awareness and civil space exploration engineering and decision making processes.

Carrico, T.; Langster, T.; Carrico, J.; Alfano, S.; Loucks, M.; Vallado, D.

179

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…

Hines, Melissa; Kaufman, Francine R.

1994-01-01

180

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

Microsoft Academic Search

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 3608 body rotation (tumbling) was the most common sensation (felt by 80% of

Robert S Allison; Ian P Howard; James E Zacher

1999-01-01

181

Design and Performance Analysis of GPS Based Precise Relative Navigation for Rendezvous and Formation Flying Missions in Low Earth Orbit  

NASA Astrophysics Data System (ADS)

Precise relative GPS navigation is essential technology for rendezvous and formation flying of spacecraft in Low Earth Orbit. Key design issues of precise relative GPS navigation software are studied and a novel formulation is proposed for the mission which requires high accuracy when the separation distance is up to several km. The navigation filter estimates float navigation solutions by extended Kalman filter with elaborate dynamics models, and resolves ambiguities of integer carrier phase biases to achieve high accuracy fix navigation solutions. A relative navigation software with the proposed formulation is implemented and evaluated in two different ways. One is a test using spacebourne GPS receivers and a GPS signal simulator to evaluate the performance and sensitivity of the software against variation of parameters. The other is a test using actual telemetry data from Gravity Recovery and Climate Experiment (GRACE) to demonstrate the software performance. The design, implementation, and results of the evaluation are presented and discussed on this paper.

Yamamoto, Toru

182

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

183

Testing heterogeneity in faunal assemblages from archaeological sites. Tumbling and trampling experiments at the early-Middle Pleistocene site of Gesher Benot Ya’aqov (Israel)  

Microsoft Academic Search

The current paper reports an experimental case study to test the heterogeneity of faunal assemblages from the Early-Middle Pleistocene Layers V-5 and V-6 of the Gesher Benot Ya’aqov Acheulian site (Israel). Tumbling and trampling experiments were initiated to gain qualitative insight into processes of bone modification and to assess the timing of the biostratonomic chronology, as it was assumed that

Sabine Gaudzinski-Windheuser; Lutz Kindler; Rivka Rabinovich; Naama Goren-Inbar

2010-01-01

184

Maneuver strategy for NEAR’s rendezvous with 433 Eros 1 1 Paper IAF 97-A4.01. presented at the 48th International Astronautical Congress, 6–10 October, 1997, Turin, Italy  

Microsoft Academic Search

On 17 February, 1996, a Delta-2 rocket placed NASA’s Near-Earth Asteroid Rendezvous (NEAR) spacecraft into a 2-year ?VEGA trajectory that will rendezvous with the large near-Earth asteroid, 433 Eros in early January 1999. This paper discusses the strategy for performing NEAR’s two large deterministic ?Vs, the Deep Space Maneuver (DSM; 269 m\\/s) 4 months after aphelion of the initial 2-year orbit

David W Dunham; James V McAdams; Larry E Mosher; Clifford E Helfrich

2000-01-01

185

Tumbling through a landscape: Evidence of instabilities in high-dimensional moduli spaces  

NASA Astrophysics Data System (ADS)

We argue that a generic instability afflicts vacua that arise in theories whose moduli space has large dimension. Specifically, by studying theories with multiple scalar fields we provide numerical evidence that for a generic local minimum of the potential the usual semiclassical bubble nucleation rate, ?=Ae-B, increases rapidly as function of the number of fields in the theory. As a consequence, the fraction of vacua with tunneling rates low enough to maintain metastability appears to fall exponentially as a function of the moduli space dimension. We discuss possible implications for the landscape of string theory. Notably, if our results prove applicable to string theory, the landscape of metastable vacua may not contain sufficient diversity to offer a natural explanation of dark energy.

Greene, Brian; Kagan, David; Masoumi, Ali; Mehta, Dhagash; Weinberg, Erick J.; Xiao, Xiao

2013-07-01

186

In-Flight Calibration of the Near Earth Asteroid Rendezvous Mission's Near Infrared Spectrometer I. Initial Calibrations  

NASA Astrophysics Data System (ADS)

The Near Infrared Spectrometer (NIS) instrument on the Near Earth Asteroid Rendezvous (NEAR) spacecraft performed a comprehensive series of in-flight tests to validate its preflight radiometric characteristics and to characterize instrument stability, pointing, and co-alignment with other instruments under flight conditions. The results of these tests form the basis of the NIS data reduction and calibration procedure and will support the ability of NIS to achieve its science goal of spectrally mapping NEAR's target asteroid, 433 Eros. Key results include the following: (i) Radiometric calibration of NIS has been confirmed to be accurate to within 4-10%, based on NIS measurements of the Earth and Moon and comparisons to radiances derived from other (NEAR and non-NEAR) optical instruments; (ii) The radiometric response has been demonstrated to be stable on the scale of months; (iii) Gradual, expected detector sensitivity decay of 1-3% over 2 years of operations in space has been characterized; (iv) Temperature dependencies of detector response are identified and characterized; (v) The co-alignment of NIS with the Multi-Spectral Imager (MSI) and with respect to other NEAR instruments has been determined; (vi) A calibration program (NISCAL) that applies appropriate functions and algorithms to convert raw instrument data to analyzable spectra has been developed; (vii) Remaining unresolved instrument calibration and characterization issues have been identified, to be resolved with the help of approach and orbital observations from the main mission.

Izenberg, Noam R.; Bell, James F.; Warren, Jeffery W.; Murchie, Scott L.; Peacock, Keith; Darlington, E. Hugo; Carcich, Brian; Chapman, Clark; Clark, Beth E.; Harch, Ann; Heyler, Gene; Joseph, Jonathan; Martin, Patrick; McFadden, Lucy; Merline, Bill; Robinson, Mark; Veverka, Joseph; Wellnitz, Dennis

2000-12-01

187

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

188

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

189

??????? ???????? ?? RendezVous: ?????? ?????? ? ??? ?????  

Microsoft Academic Search

The article examines Sergei Sharshun's prose, with a particular focus on Put' pravyi (1934). Emigré critics interpreted this text in light of a testimonial, confessional genre reminiscent of the “human document”, which was prevalent during that time. The present analysis challenges this traditional reception by engaging with the novel's diverse, if implicit, intertexts, ranging from Dada and Surrealism to Soviet

Maria Rubins

2007-01-01

190

Mountain Man Measurement Rendezvous  

NSDL National Science Digital Library

In this math lesson, learners participate in several activities where they apply measurement skills. Learners explore how the Mountain Men played an important part in the history of the American frontier and more importantly, how the Mountain Men used different techniques for making measurements in their daily activities. At the various stations, learners measure their jump distances, handfuls of "gold," water-soaked sponges, "buffalo chip" throws, arm spans, "stone" throws, "arrow" tosses, foot sizes, pots of beans, and "shooting" distances. This activity works well outside.

Lessonplans, Utah

2012-10-22

191

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.

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

2009-01-01

192

Detection of nano-second internal motion and determination of overall tumbling times independent of the time scale of internal motion in proteins from NMR relaxation data.  

PubMed

The usual analysis of (15)N relaxation data of proteins is straightforward as long as the assumption can be made that the backbone of most residues only undergoes fast (ps), small amplitude internal motions. If this assumption cannot be made, as for example for proteins which undergo domain motions or for unfolded or partially folded proteins, one needs a method to establish for each residue whether it undergoes fast (ps) or slow (ns) internal motion. Even then it is impossible to determine the correct overall tumbling time, tau(m)(0), via the usual method from the ratio of the longitudinal and transverse relaxation times, if the majority of residues do not undergo fast, small amplitude internal motions. The latter problem is solved when tau(m)(0) can be determined independent of the time scale, tau(i), or the amplitude, S(2), of the internal motion. We propose a new protocol, called PINATA, for analyzing (15)N relaxation data acquired at minimally two field strengths, where no a priori assumption about time scales or amplitude of internal motions needs to be made, and overall tumbling can either be isotropic or anisotropic. The protocol involves four steps. First, for each residue, it is detected whether it undergoes ps- or ns-internal motion, via the combination of the ratio of the longitudinal relaxation time at two fields and the hetero-nuclear NOE. Second, for each residue tau(m)(0) and the exchange broadening, Rex, are iteratively determined. The accuracy of the determination of tau(m)(0) is ca. +/-0.5 ns and of Rex ca +/- 0.7 s(-1), when the relaxation data are of good quality and tau(m)(0)>5 ns, S(2)>0.3, and tau(i)< approximately 3 ns. Third, given tau(m)(0) and Rex, step 1 is repeated to iteratively improve on the internal motion and obtain better estimates of the internal parameter values. Fourth, final time scales and amplitudes for internal motions are determined via grid search based fitting and chi(2)-analysis. The protocol was successfully tested on synthetic and experimental data sets. The synthetic dataset mimics internal motions on either fast or slow time scales, or a combination of both, of either small- or large amplitude, superimposed onto anisotropic overall motion. The procedures are incorporated into MATLAB scripts, which are available on request. PMID:14512728

Larsson, Göran; Martinez, Gary; Schleucher, Jürgen; Wijmenga, Sybren S

2003-12-01

193

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.

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

2002-01-01

194

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

195

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.

196

Tumbling: From Rally Cars to Toast  

ERIC Educational Resources Information Center

The article by Rod Cross describing the translational and rotational motion of the "Launch of a Vehicle from a Ramp" motivated us to create two computer models showing this type of dynamical behavior.

Belloni, Mario; Christian, Wolfgang

2012-01-01

197

Unsteady aerodynamics of fluttering and tumbling plates  

Microsoft Academic Search

We investigate the aerodynamics of freely falling plates in a quasi-two-dimensional flow at Reynolds number of 103, which is typical for a leaf or business card falling in air. We quantify the trajectories experimentally using high-speed digital video at sufficient resolution to determine the instantaneous plate accelerations and thus to deduce the instantaneous fluid forces. We compare the measurements with

U. P ESAVENTO; Z. J ANE W ANG

2005-01-01

198

Tumbling: From Rally Cars to Toast  

NASA Astrophysics Data System (ADS)

The article1 by Rod Cross describing the translational and rotational motion of the ``Launch of a Vehicle from a Ramp'' motivated us to create two computer models showing this type of dynamical behavior.

Belloni, Mario; Christian, Wolfgang

2012-10-01

199

Tumbling: From Rally Cars to Toast  

ERIC Educational Resources Information Center

|The article by Rod Cross describing the translational and rotational motion of the "Launch of a Vehicle from a Ramp" motivated us to create two computer models showing this type of dynamical behavior.|

Belloni, Mario; Christian, Wolfgang

2012-01-01

200

Efficient and tumble similar set retrieval  

Microsoft Academic Search

Set value attributes are a concise and natural way to model complex data sets. Modern Object Relational systems support set value attributes and allow various query capabilities on them. In this paper we initiate a formal study of indexing techniques for set value attributes based on similarity, for suitably defined notions of similarity between sets. Such techniques are necessary in

Aristides Gionis; Dimitrios Gunopulos; Nick Koudas

2001-01-01

201

Wet Autogenous Grinding in Tumbling Mills.  

National Technical Information Service (NTIS)

After a general introduction the article discusses at length the various grinding mechanisms operative in autogenous grinding. The viewpoints developed are then used for a review of the operational aspects, especially concerning process limitations, regul...

M. Digre

1969-01-01

202

Operator learning effects in teleoperated rendezvous & docking  

NASA Astrophysics Data System (ADS)

Teleoperation of spacecraft proximity operations and docking requires delicate timing and coordination of spacecraft maneuvers. Experience has shown that human operators show large performance fluctuations in these areas, which are a major factor to be addressed in operator training. In order to allow the quantification of the impact of these human fluctuations on control system performance and the human perception of this performance, a learning curve study was conducted with teleoperated final approach and docking scenarios. Over a period of ten experiment days, three test participants were tasked with repeatedly completing a set of three training scenarios. The scenarios were designed to contain different combinations of the major elements of any final approach and docking situation, and to feature an increasing difficulty level. The individual difficulty levels for the three operators furthermore differed in the level of operator support functions available in their human-machine interfaces. Operator performance in the test scenarios were evaluated in the fields approach success and precision, docking safety, and approach efficiency by a combination of recorded maneuver data and questionnaires. The results show that operator experience and the associated learning curves increase operator performance substantially, regardless of the support system used. The paper also shows that the fluctuations in operator performance and self-perception are substantial between as well as within experiment days, and must be reckoned with in teleoperation system design and mission planning.

Wilde, M.; Harder, J.; Purschke, R.

203

Low power rendezvous in embedded wireless networks  

Microsoft Academic Search

In the future, wireless networking will be embedded into a wide variety of common, everyday objects. In many embedded networking situations, the communicating nodes will be very small and battery powered. For this reason, it is crucial that power consumption is as low as possible. A technique for reducing power consumption is to place nodes into a sleep mode whenever

Terry Todd; Frazer Bennett; Alan Jones

2000-01-01

204

The multi-agent rendezvous problem  

Microsoft Academic Search

This paper is concerned with the collective behavior of a group of n > 1 mobile autonomous agents, labelled 1 through n, which can all move in the plane. Each agent is able to continuously track the positions of all other agents currently within its \\

J. Lin; A. S. Morse; B. D. O. Anderson

2003-01-01

205

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.

206

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

207

Full relaxation matrix analysis of apparent cross-correlated relaxation rates in four-spin systems  

NASA Astrophysics Data System (ADS)

Cross-correlated relaxation (CCR) rates are an established tool for the extraction of relative bond orientations in biomolecules in solution. CCR between dipolar interactions in four-spin systems is a particularly well-suited mechanism. In this paper, a simple approach to analyze systematic experimental errors is formulated in a subspace of the complete four-spin Hilbert space. It is shown that, contrary to the common assumption, the secular approximation of the relaxation matrix is marginal for the most prominent spin systems. With the main focus on the model protein GB3 at room temperature, it is shown that the apparent experimental CCR rates have errors between -12% and +4% for molecules with a molecular tumbling time of 3.5 ns. Although depending on the specific pulse sequence used, the following rule-of-thumb can be established: Judged by absolute values, the errors for H?-C?/H?-C?, HN-N/C?-C?, HN-N/C?-C? and HN-N/H?-C? CCR rates can safely be neglected. However, errors for HN-N/HN-N and HN-N/H?-C? CCR rates are on the order of 0.1-0.3 s-1 and must be considered. Tabulated correction factors may be used for their extraction. If larger systems are studied, in most cases the errors cannot be neglected anymore. On the other hand, well-calibrated pulses can safely be assumed to be perfect.

Vögeli, Beat

2013-01-01

208

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

209

What are the ratings rating?  

Microsoft Academic Search

6 objective variables in the public domain were found to predict A. Cartter's ratings of psychology departments: (a) number of areas of specialization (b) number of faculty, (c) number of PhD's graduated between 1960-1964, (d) number of full-time students, (e) number of part-time students, and (f) ratio of part to full-time students. It is suggested that ratings obtained by Cartter

Charles F. Elton; Harriett A. Rose

1972-01-01

210

Quantitative determination of NOE rates in perdeuterated and protonated proteins: Practical and theoretical aspects  

NASA Astrophysics Data System (ADS)

Precision and accuracy are the limiting factors in extracting structural and dynamic information from experimental NOEs. In this study, error sources at all stages of such an analysis are identified and errors are estimated. The data set of HN-HN cross-relaxation rates obtained from triple-labeled ubiquitin presented in [B. Vögeli, T.F. Segawa, D. Leitz, A. Sobol, A. Choutko, D. Trzesniak, W. van Gunsteren, R. Riek, J. Am. Chem. Soc. 131 (47) (2009) 17215-17225] is extended to rates obtained from a double-labeled sample. Analog data sets are presented for GB3. It is shown that quantitative NOE rates can be determined with high accuracy from both triple-labeled as well as double-labeled samples. The quality of experimental cross-relaxation rates obtained from 3D HXQC-NOESY and NOESY-HXQC experiments is discussed. It is shown that NOESY-HXQC experiments provide rates of the same quality as HXQC-NOESY if both diagonal and cross peaks for a spin pair can be resolved. Expressions for cross-relaxation rates for anisotropically tumbling molecules exhibiting fast and slow motion are derived. The impact of anisotropy on the prediction of cross-relaxation rates and on the conversion of experimental rates into effective distances is discussed. For molecules with anisotropy D/D? up to five the distance error is smaller than 2%. Finally, “averaged order parameters” are calculated for specific secondary-structural elements showing similar trends for ubiquitin and GB3.

Vögeli, Beat; Friedmann, Michael; Leitz, Dominik; Sobol, Alexander; Riek, Roland

2010-06-01

211

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.

212

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…

Coffey, Patrick; Mattox, Steve

2006-01-01

213

Strategy for capturing of a tumbling space debris  

Microsoft Academic Search

In general space debris objects do not possess much convenient features and are non-cooperative. In such cases, since the conditions for capture are not favorable, tracking errors will lead to loading, and momentum transfer will occur during the capture process.In most cases, detailed mass and inertial characteristics of the target are unknown, either because design details are unavailable or due

Shin-Ichiro Nishida; Satomi Kawamoto

2011-01-01

214

The credit ratings game  

Microsoft Academic Search

The collapse of so many AAA-rated structured finance products in 2007-2008 has brought renewed attention to the causes of ratings failures and the conflicts of interest in the Credit Ratings Industry. We provide a model of competition among Credit Ratings Agencies (CRAs) in which there are three possible sources of conflicts: 1) the CRA conflict of interest of understating credit

Patrick Bolton; Xavier Freixas; Joel Shapiro

2010-01-01

215

The Credit Ratings Game  

Microsoft Academic Search

The collapse of so many AAA-rated structured finance products in 2007-2008 has brought renewed attention to the causes of ratings failures and the conflicts of interest in the Credit Ratings Industry. We provide a model of competition among Credit Ratings Agencies (CRAs) in which there are three possible sources of conflicts: 1) the CRA conflict of interest of understating credit

Patrick Bolton; Xavier Freixas; Joel Shapiro

2010-01-01

216

MPAA Ratings Creep  

Microsoft Academic Search

The term “ratings creep” refers to the belief that various types of adult content escalate in films with the same rating over time. The purpose of this study was to test the ratings creep hypothesis through a quantitative analysis of films from 1988, 1997, and 2006 in the PG-13 rating category used by the Motion Picture Association of America (MPAA).

Ron Leone; Laurie Barowski

2011-01-01

217

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.

Zhou, Hua; Lange, Kenneth

2010-01-01

218

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

219

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

220

Autonomous Unmanned Aerial Vehicle Rendezvous for Automated Aerial Refueling.  

National Technical Information Service (NTIS)

As unmanned aerial vehicles (UAVs) increase in capability, the ability to refuel them in the air is becoming more critical. Aerial refueling will extend the range, shorten the response times, and extend loiter time of UAVs. Executing aerial refueling auto...

B. S. Burns

2007-01-01

221

‘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

222

Consideration of radar target glint from ST during OMV rendezvous  

NASA Astrophysics Data System (ADS)

The nature of radar target glint and the factors upon which it depends when using the Hubble Space Telescope as a radar target is discussed. An analysis of the glint problem using a 35 MHz or 94 MHz radar on the orbital maneuvering vehicle is explored. A strategy for overcoming glint is suggested.

McDonald, M. W.; Malone, L. B.; Gleason, E. H.

1985-09-01

223

Consideration of radar target glint from ST during OMV rendezvous  

Microsoft Academic Search

The nature of radar target glint and the factors upon which it depends when using the Hubble Space Telescope as a radar target is discussed. An analysis of the glint problem using a 35 MHz or 94 MHz radar on the orbital maneuvering vehicle is explored. A strategy for overcoming glint is suggested.

M. W. McDonald; L. B. Malone; E. H. Gleason

1985-01-01

224

Rendezvous with History: Franklin and Eleanor Roosevelt State Historical Site  

NSDL National Science Digital Library

Among the many family homes that have served as places of tranquility for U.S. presidents, the grounds and buildings of Hyde Park, New York loom large within the life experiences of the Roosevelt family. This site, provided by the Poughkeepsie Journal, offers a virtual tour of the Franklin D. Roosevelt Historic Site, complete with 360 degree views, essays, and a timeline of important events related to the family estate. Visitors will want to begin by perusing the fine interactive map of the grounds, as they can take an inside look at such buildings as the Presidential Library, the Henry A. Wallace Visitor Center, and the historic home of Franklin and Eleanor Roosevelt, Springwood. The stories section really brings out the spirit of both FDR and Eleanor, as they talk about their lives and legacies, along with providing transcripts of some of FDRÂs most well-known speeches, such as the Four Freedoms delivery and the declaration of war against Japan. Finally, visitors will want to also take a look through some of the 360-degree views offered here, including a tour of the famed room where the Fireside Chats were delivered and FDRÂs bedroom.

225

Challenges to situated morality: Maintaining respectability in a sexual rendezvous  

Microsoft Academic Search

A clandestine motel operation is described, concentrating upon the staff and patrons as they attempt to maintain respectability within a context of situated morality that is shifting, challenging previously negotiated realities. The staff members tend toward a refulgent respectability, using vocabularies of denial to maintain respectability. Patrons, categorized as regular customers, special customers, careful people and problem people, may seek

J. Robert Lilly; Richard A. Ball

1980-01-01

226

Natural killer cells and dendritic cells: rendezvous in abused tissues  

Microsoft Academic Search

Natural killer (NK) cells and dendritic cells (DCs) are two types of specialized cell of the innate immune system, the reciprocal interaction of which results in a potent, activating cross-talk. For example, DCs can prime resting NK cells, which, in turn, after activation, might induce DC maturation. However, NK cells negatively regulate the function of DCs also by killing immature

Alessandro Moretta

2002-01-01

227

Efficient Rendezvous Algorithms for Mobility-Enabled Wireless Sensor Networks  

Microsoft Academic Search

Recent research shows that significant energy saving can be achieved in mobility-enabled wireless sensor networks (WSNs) that visit sensor nodes and collect data from them via short-range communications. However, a major performance bottleneck of such WSNs is the significantly increased latency in data collection due to the low movement speed of mobile base stations. To address this issue, we propose

Guoliang Xing; Minming Li; Tian Wang; Weijia Jia; Jun Huang

2012-01-01

228

NEP for a Kuiper Belt Object Rendezvous Mission  

Microsoft Academic Search

Kuiper Belt Objects (KBOs) are a recently-discovered set of solar system bodies which lie at about the orbit of Pluto (40 AU) out to about 100 astronomical units (AU). There are estimated to be about 100,000 KBOS with a diameter greater than 100 km. KBOS are postulated to be composed of the pristine material which formed our solar system and

MICHAEL G. HOUTS; ROGER X. LENARD; RONALD J. LIPINSKI; BRUCE PATTON; DAVID I. POSTON; STEVEN A. WRIGHT

1999-01-01

229

Saturn ring rendezvous mission utilizing a tethered subsatellite  

Microsoft Academic Search

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

Larry E. Bright

1990-01-01

230

NEP for a Kuiper Belt Object rendezvous mission  

Microsoft Academic Search

Kuiper Belt Objects (KBOs) are a recently-discovered set of solar system bodies which lie at about the orbit of Pluto (40 AU) out to about 100 astronomical units (AU). There are estimated to be about 100,000 KBOs with a diameter greater than 100 km. KBOs are postulated to be composed of the pristine material which formed our solar system and

Ronald J. Lipinski; Roger X. Lenard; Steven A. Wright; Michael G. Houts; Bruce Patton; David I. Poston

2000-01-01

231

Optimal trajectories for a multiple rendezvous mission to asteroids  

Microsoft Academic Search

Optimal trajectories are designed for an ion-driven spacecraft from earth to the asteroid 8 Flora with an intermediate stop at 4 Vesta under the constraints imposed by a low-cost mission scenario. For each set of boundary conditions and constraints, the problem is transformed into a multipoint boundary value problem which is solved by the multiple shooting method. Complete flight trajectories

R. Bulirsch; R. Callies

1991-01-01

232

Low Power Rendezvous and RFID Wakeup for Embedded Wireless Networks  

Microsoft Academic Search

In the future, embedded wireless networking will be included in many common, everyday objects. It is expected that this added functionality will enable an enormous varie ty of applications and services which have yet to be achieved or envisioned. Possible examples include sensor systems, smart toys and games, smart appliances, electronic access control, and a myriad of other in-home, business,

Milan Nosovic; Terry Todd

2000-01-01

233

Glomerular filtration rate  

MedlinePLUS

Glomerular filtration rate (GFR) is a test used to check how well the kidneys are working. Specifically, it estimates ... with several other factors to estimate your glomerular filtration rate (GFR). Different formulas are used for adults ...

234

Metabolic Rate Measurement System.  

National Technical Information Service (NTIS)

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,...

K. Koester W. Crosier

1980-01-01

235

Chalcopyrite dissolution rate laws  

Microsoft Academic Search

Meta-analysis of 173 rate measurements from 21 publications was used to develop rate laws for chalcopyrite dissolution under environmentally relevant conditions. Multiple linear regression analysis of 28 data for nonoxidative chalcopyrite dissolution in the presence of O2 and Cl? produced the following rate law:r=10-1.52e-28200\\/RT[H+]1.68Here, r is the rate of chalcopyrite dissolution in units of molm?2s?1 where the surface area is

Bryn E. Kimball; J. Donald Rimstidt; Susan L. Brantley

2010-01-01

236

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

237

Gamma rate versus time  

Microsoft Academic Search

Initial- and residual-gamma rates were measured as a function of time at various distances from high-yield thermonuclear detonations. Initial gamma rate versus time was measured at fixed distances from ground zero. In particular, measurements were made of the effect on initial-gamma rate caused by the passage of the shock front from ground zero through the detector station. Residual-gamma rate versus

P. Brown; G. Carp

1954-01-01

238

Rates of Spontaneous Mutation  

Microsoft Academic Search

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

John W. Drake; Brian Charlesworth; Deborah Charlesworth; James F. Crow

1998-01-01

239

ESTIMATING BIODEGRADATION RATES  

EPA Science Inventory

This two hour segment of the course reviews the four types of rate constants, illustrates their interactions to produce the behavior of a plume over time, provides representative values of rate constants from the literature, illustrates methods to extract rate constants from fiel...

240

The Credit Ratings Game  

Microsoft Academic Search

The spectacular failure of top-rated structured finance products has brought renewed attention to the conflicts of interest of Credit Rating Agencies (CRAs). We model both the CRA conflict of understating credit risk to attract more business, and the issuer conflict of purchasing only the most favorable ratings (issuer shopping), and examine the effectiveness of a number of proposed regulatory solutions

Patrick Bolton; Xavier Freixas; Joel Shapiro

2009-01-01

241

Movie Rating Prediction  

Microsoft Academic Search

The Internet Movie Database (IMDB) is one of the largest online resources for general movie information combined with a forum in which users can rate movies. We investigate the extent to which a movie's average user rating can be predicted after learning the relationship between the rating and a movie's various attributes from a training set. Two methods are evaluated:

Armstrong Nick; Kevin Yoon

242

River Flow Rate  

NSDL National Science Digital Library

Students build on their understanding and feel for flow rates, as gained from the associated Faucet Flow Rate activity, to estimate the flow rate of a local river. The objective is to be able to relate laboratory experiment results to the environment. They use the U.S. Geological Survey website (http://waterdata.usgs.gov/nwis/rt) to determine the actual flow rate data for their river, and compare their estimates to the actual flow rate. For this activity to be successful, choose a nearby river and take a field trip or show a video so students gain a visual feel for the flow of the nearby river.

Civil And Environmental Engineering Department

243

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.

Zhou, Huan-Xiang

2012-01-01

244

Measuring Evolutionary Rates  

NASA Astrophysics Data System (ADS)

We have been using extensive data sets of time series photometry acquired over the last three decades to measure the rate of change of the pulsation periods of white dwarf stars, which in turn measure their evolutionary rates. The evolution of an isolated white dwarf is dominated by cooling. However, hot pre white dwarfs also show significant radius evolutionary rates. After 30 years of observations we finally measured the cooling rate of a DAV, G117-B15A, in good agreement with the theoretical predictions. But other periodicities for G 117-B15A, and a similar DAV, R 548, show faster rates of period changes. We also observe faster evolutionary rates in other classes of white dwarf variables, e.g., the DOV PG1 159-035 and the DBV GD 358. These fast changes are not explained by the theoretical models to date.

Kepler, S. O.; Costa, J. E. S.; Mukadam, A.; Mullally, F.; Winget, D. E.; Nather, R. E.; Sullivan, D.

2005-07-01

245

Rate of Solution Demonstration  

NSDL National Science Digital Library

In this chemistry demonstration, learners investigate the factors that increase the rate of dissolution for a solid. Learners will compare how crushing sugar cubes, stirring and water temperature affect the rate at which the sugar dissolved. This resource guide includes extensions and notes about factors that accelerate dissolution and Henry's Law.

House, The S.

2013-05-15

246

Applications of Reaction Rate  

ERIC Educational Resources Information Center

|This article presents an assignment in which students are to research and report on a chemical reaction whose increased or decreased rate is of practical importance. Specifically, students are asked to represent the reaction they have chosen with an acceptable chemical equation, identify a factor that influences its rate and explain how and why…

Cunningham, Kevin

2007-01-01

247

Suburbanization and homeownership rates  

Microsoft Academic Search

Homeownership rates in suburbs are much higher than in central cities. This paper shows that the systematic difference between homeownership rates causes suburbanization. We consider an economy with several regions: the central city, where most households rent, and the suburbs, where most own. Households migrate and vote on local policies. Renters do not consider the effect of policies on house

Wolfgang R. Köhler

2008-01-01

248

Controlled Rate Cooling  

Technology Transfer Automated Retrieval System (TEKTRAN)

Controlled-rate cooling is one of several techniques available for the long-term storage of plants in liquid nitrogen. In this technique samples are slowly cooled to an intermediate temperature and then plunged in liquid nitrogen. Controlled rate cooling is based on osmotic regulation of cell conte...

249

Distance Rate Time  

NSDL National Science Digital Library

Measurement is one of the core NCTM Principals and Standards for School Mathematics content standards, and rate is central to its practical application. While most middle school students know the distance-rate-time formula, they may still benefit from a closer study of the relationship through these online resources.

National Science Digital Library (NSDL) Middle School Portal Staff

2008-03-10

250

Tests of Rating Models  

ERIC Educational Resources Information Center

The study reports empirical tests of Anderson's, Haubensak's, Helson's, and Parducci's rating models when two end anchors are used for rating. The results show that these models cannot predict the judgment effect called here the Dai Pra effect. It is shown that an extension of Anderson's model is consistent with this effect. The results confirm…

Masin, Sergio Cesare; Busetto, Martina

2010-01-01

251

Exchange Rate Economics  

Microsoft Academic Search

This book describes and evaluates the literature on exchange rate economics. It provides a wide-ranging survey, with background on the history of international monetary regimes and the institutional characteristics of foreign exchange markets, an overview of the development of conceptual and empirical models of exchange rate behavior, and perspectives on the key issues that policymakers confront in deciding whether, and

Peter Isard

252

Eliciting individual discount rates  

Microsoft Academic Search

Controlled laboratory conditions using monetary incentives have been utilized in previous studies that examine individual discount rates, and researchers have found several apparently robust anomalies. We conjecture that subject behavior in these experiments may be affected by (uncontrolled) factors other than discount rates. We address some experimental design issues and report a new series of experiments designed to elicit individual

Maribeth Coller; Melonie B. Williams

1999-01-01

253

Verifying Exchange Rate Regimes  

Microsoft Academic Search

July 2000One reason intermediate exchange rate regimes have fallen out of favor is that they are not transparent or easy to verify. A simple peg or a simple float may be easier for market participants to verify than a more complicated intermediate regime.Credibility and transparency are at the core of the current debate about exchange rate regimes. The steady growth

Sergio Schmukler; Jeffrey Frankel; Eduardo Fajnzylber

1999-01-01

254

Applications of Reaction Rate  

ERIC Educational Resources Information Center

This article presents an assignment in which students are to research and report on a chemical reaction whose increased or decreased rate is of practical importance. Specifically, students are asked to represent the reaction they have chosen with an acceptable chemical equation, identify a factor that influences its rate and explain how and why it…

Cunningham, Kevin

2007-01-01

255

Athletes' Graduation Rates.  

ERIC Educational Resources Information Center

|A National Collegiate Athletic Association report on athletes' graduation rates provides data that can support either side of the debate over academic standards. Rising academic requirements for incoming athletes may cause higher graduation rates, but may also force blacks out of sports in disproportionate numbers. Graduation data for 1987-88 and…

Blum, Debra E.

1995-01-01

256

Behavior Rating Scale.  

ERIC Educational Resources Information Center

The Behavior Rating Scale measures behavioral skills by observing the child during the administration of other tests. The rating dimensions include independence, concentration, tractability, attitude and disposition toward testing, and overflow behavior. All are scored on a scale of 0-4, low to high. (PR)

University City School District, MO.

257

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

258

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.

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

2010-01-01

259

Rates of spontaneous mutations  

Microsoft Academic Search

ABSTRACT 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, 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

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

1998-01-01

260

ESR (Erythrocyte Sedimentation Rate) Test  

MedlinePLUS

... rate; Sedimentation rate; Westergren sedimentation rate Formal name: Erythrocyte Sedimentation Rate Related tests: C-reactive protein (CRP) ; ... None The Test Sample What is being tested? Erythrocyte sedimentation rate (ESR) is an indirect measure of ...

261

Carborane Burning Rate Catalysts.  

National Technical Information Service (NTIS)

New carborane burning rate accelerators designed for use in solid propellants, without the problems associated with current accelerators, have been prepared. High molecular weight, non-volatile derivatives of bis(1-carboranylmethyl) and bis-(1-carboranyle...

R. Fitzgerald L. J. Rosen R. L. Lou

1973-01-01

262

Rice Drying Rates.  

National Technical Information Service (NTIS)

Rice is ordinarily harvested at moisture contents above safe storage levels, so additional drying is usually necessary. The purpose of the research discussed in this report was to determine the factors which affect rice drying rates. The basic approach us...

J. F. Robayo H. B. Pfost

1973-01-01

263

Interest Rates and Inflation  

Microsoft Academic Search

A relation between interest rates and inflation is presented using a two component economic model and a simple general principle. Preliminary results indicate a remarkable similarity to classical economic theories, in particular that of Wicksell.

Michael Coopersmith

2011-01-01

264

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

265

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

266

Medicaid Capitation Rate Development.  

National Technical Information Service (NTIS)

This project was designed to study the feasibility of using the Medicaid Statistical Information System (MSIS) data calculate upper payment limits and capitation rate for Medicaid managed care plans. Alabama, Kentucky, Maine and Wisconsin were chosen as t...

G. Trapnell R. Chu A. Wade E. Peppe R. Lambert

1996-01-01

267

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 approach relies on the fact that all burning solids are first converted into a gas. By understanding the rate of gasification and other physical properties of a given solid material, the experiments will emulate the burning process by carefully controlling a gas flame

Kristine Rainey

2013-01-11

268

Rate of return inequity  

SciTech Connect

Utility stock and bond prices will be increasingly sensitive to differences between allowed rates of return and market rates for comparable investments. Allowed rates of return on equity (ROE) are traditionally set at a level commensurate with the returns on alternative investments of comparable risk. This focus on financial market conditions is becoming increasingly important as deregulation and market innovations increase competition among alternate financial instruments. Accurate estimates of the market rate are essential if the utility is to compete for investment capital. The discounted cash flow (DCF) model provides one widely used approach for estimating the market-determined rate of return. Jurisdictions using the model prefer the annual version, which assumes that the utility pays only one annual dividend. This assumption, however, reduces the accuracy of the estimate for utilities that pay quarterly dividends. Indeed, using an annual model to approximate the DCF model for a firm that pays quarterly dividends consistently and significantly underestimates the market rate of return. Despite the importance of such understatement, only two states permit a quarterly version of the DCF model: Illinois and Nevada. This article highlights the effect of financial reform and deregulation on the process for determining the allowed ROE, explains the relevance of annual and quarterly dividends for the DCF model, and discusses in nontechnical terms two methods for adjusting the DCF model to account for quarterly dividend payments.

Cargill, T.F.; Wendel, J.

1994-04-15

269

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.

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

1998-01-01

270

Interest rates factor model  

NASA Astrophysics Data System (ADS)

Interdependence of the interest rates of the US, the UK, and Japan is analyzed in this work by means of spectral analysis and network methods. A predominant effective factor in the interest rate market is which country floats a bond issue, and a minor effective factor is time to maturity of bonds. Power-law cross-correlation among different countries is analyzed by the detrended cross-correlation analysis method. Long-range cross-correlation is found between the first factors of interest rate, while there is no cross-correlation between some of the second factors. The tail dependency is indicated by tail indices from Archimedean copulas, including an empirical copula. In contrast to other pairs, the US–UK first factor pair has tail dependencies in both the upper-tail and lower-tail. Dynamic properties of interest rate are modeled by a stochastic volatility model. The properties of mean reverting and volatility clustering are observed and reflected in this model. The proposed simulation method combines the dependence structures and the factor dynamics model; it simultaneously describes the interest rates of different countries.

Lee, Sangwook; Kim, Min Jae; Kim, Soo Yong

2011-07-01

271

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

272

High Growth Rate MOVPE  

NASA Astrophysics Data System (ADS)

In this chapter, growth mechanism of GaN and AlGaN by MOVPE is described in detail. The parasitic reaction that generates particulates in vapor phase is the most probable limiting factor of maximum growth rate of GaN and AlGaN. Both experimental and quantum chemical study of vapor phase reaction between organo-metals and ammonia is described. From the close insight of vapor phase reaction, high flow speed three layered gas injection has been developed. By employing this three-layer gas-injection, GaN was grown with growth rate as high as 28?m/h at atmospheric pressure. As long as the present growth conditions are concerned, SIMS and XRD results suggested that the growth rate of 12?m/h would be a practical limitation of good quality material in terms of electrical and structural properties.

Matsumoto, K.; Tokunaga, H.; Ubukata, A.; Ikenaga, K.; Fukuda, Y.; Yano, Y.; Tabuchi, T.; Kitamura, Y.; Koseki, S.; Yamaguchi, A.; Uematsu, K.

273

Strain-rate effects for high-strain-rate computations  

Microsoft Academic Search

This paper examines the effect of strain rates for computations involving high strain-rates, beyond 103 s - 1. Although it is generally agreed that there is an enhanced rate effect at these higher rates, there is uncertainty regarding the interpretation of dynamic test data, the form of the high-rate effect, and the effect of the high rates on practical problems

G. R. Johnson; T. J. Holmquist; C. E. Anderson Jr.; A. E. Nicholls

2006-01-01

274

Automatic rate adaptation  

Microsoft Academic Search

Rate adaptation is a fundamental primitive in wireless networks. Since wireless channel strength varies quickly and unpredictably, senders have to constantly measure the channel and correspondingly adapt the bitrate so that the transmitted packet gets correctly decoded. Prior approaches to this problem can be divided into two classes: those that require constant and expensive feedback from the receiver about channel

Aditya Gudipati; Sachin Katti

2010-01-01

275

Setting Graduation Rate Thresholds.  

ERIC Educational Resources Information Center

Reviews the college completion/graduation rate thresholds developed by several states and discusses advantages and disadvantages of several statistical approaches, including use of the one standard deviation lower bound method, the logit prediction bound method, the linear regression method, and the logistic regression method. (DB)

Underwood, David G.; Rieck, James R.

1999-01-01

276

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.

277

Solvent Evaporation Rates  

Microsoft Academic Search

A system of equations for predicting the evaporation rates of solvents is presented. These equations may be used by the industrial hygienist, in conjunction with the diffusion equations developed elsewhere, to predict the atmospheric concentrations of vapors from spilled toxic liquids. The equations are derived from wind tunnel tests and applied to predictions for spills both indoors and outdoors.

DOUGLAS C. GRAY

1974-01-01

278

Recombination Rates in  

Microsoft Academic Search

Recombination occurs during meiosis to produce new allelic combinations in natural populations, making it important for studying evolution. The model system Drosophila has been crucial for understanding the mechanics underlying recombination and assessing the association between recombination rate and several evolutionary parameters. Drosophila was the first system in which genetic maps were developed using recombination frequencies between genes. Linkage maps

Mohamed A F Noor

279

Understanding Rates of Change.  

ERIC Educational Resources Information Center

This paper presents three activities on how to analyze rates of change in real-life situations using TI-83 calculators and computer-based laboratories. Activities include 24 hour temperature data, the temperature of a light bulb, and an M&M toss. Each section contains descriptions of equipment/materials, data collection, and data analysis. The…

Weil, Aurelia; Russell, Larry

280

Radiation dose rate meter  

Microsoft Academic Search

A combined dose rate meter and charger unit therefor which does not require the use of batteries but on the other hand produces a charging potential by means of a piezoelectric cylinder which is struck by a manually triggered hammer mechanism. A tubular type electrometer is mounted in a portable housing which additionally includes a geiger-muller (Gm) counter tube and

S. Kronenberg; C. R. Siebentritt

1981-01-01

281

Exchange-Rate Determination  

Microsoft Academic Search

This volume is intended to provide a survey of thought about exchange-rate determination as it emerged in the decade of the 1970s. This survey differs from many, however, in that the field itself is in a state of rapid change. Understanding the changes and the reasons for them is therefore essential if the reader is to have a basis for

Anne O. Krueger

282

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

283

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

284

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

285

Paradoxes in Film Ratings  

ERIC Educational Resources Information Center

|The author selected a simple random sample of 100 movies from the "Movie and Video Guide" (1996), by Leonard Maltin. The author's intent was to obtain some basic information on the population of roughly 19,000 movies through a small sample. The "Movie and Video Guide" by Leonard Maltin is an annual ratings guide to movies. While not all films…

Moore, Thomas L.

2006-01-01

286

Rating Scales in Schizophrenia  

Microsoft Academic Search

\\u000a In the field of schizophrenia treatment and research, psychiatric symptom rating scales have served to evaluate and elucidate\\u000a the value of antipsychotic medications and psychosocial interventions in treating this disorder. Useful scales have also been\\u000a developed to assist in measuring side effects of medications, to assess areas of cognitive functioning, to evaluate quality\\u000a of life, and to monitor medication treatment

Jennifer D. Gottlieb; Xiaoduo Fan; Donald C. Goff

287

Rates of Chemical Weathering  

NSDL National Science Digital Library

In this activity, students will investigate the weathering of rocks by chemical processes. They will use effervescent cleansing tablets as a model for rock, and vary surface area, temperature, and acidity to see how rapidly the "rock" dissolves. This investigation will help them understand three of the factors that affect the rate of chemical weathering and develop better understanding of how to design controlled experiments by exploring only one experimental variable at a time.

Passow, Michael

288

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

289

Rotational rate sensor  

DOEpatents

A rate sensor for angular/rotational acceleration includes a housing defining a fluid cavity essentially completely filled with an electrolyte fluid. Within the housing, such as a toroid, ions in the fluid are swept during movement from an excitation electrode toward one of two output electrodes to provide a signal for directional rotation. One or more ground electrodes within the housing serve to neutralize ions, thus preventing any effect at the other output electrode.

Hunter, Steven L. (Livermore, CA)

2002-01-01

290

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.

291

29 CFR 778.112 - Day rates and job rates.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Day rates and job rates. 778.112 Section 778.112...âregular Rateâ § 778.112 Day rates and job rates. If the employee is paid a flat...a day's work or for doing a particular job, without regard to the number of...

2013-07-01

292

Reduced Heart Rate Volatility  

PubMed Central

Objective: To determine if using dense data capture to measure heart rate volatility (standard deviation) measured in 5-minute intervals predicts death. Background: Fundamental approaches to assessing vital signs in the critically ill have changed little since the early 1900s. Our prior work in this area has demonstrated the utility of densely sampled data and, in particular, heart rate volatility over the entire patient stay, for predicting death and prolonged ventilation. Methods: Approximately 120 million heart rate data points were prospectively collected and archived from 1316 trauma ICU patients over 30 months. Data were sampled every 1 to 4 seconds, stored in a relational database, linked to outcome data, and de-identified. HR standard deviation was continuously computed over 5-minute intervals (CVRD, cardiac volatility–related dysfunction). Logistic regression models incorporating age and injury severity score were developed on a test set of patients (N = 923), and prospectively analyzed in a distinct validation set (N = 393) for the first 24 hours of ICU data. Results: Distribution of CVRD varied by survival in the test set. Prospective evaluation of the model in the validation set gave an area in the receiver operating curve of 0.81 with a sensitivity and specificity of 70.1 and 80.0, respectively. CVRD predict death as early as 24 hours in the validation set. Conclusions: CVRD identifies a subgroup of patients with a high probability of dying. Death is predicted within first 24 hours of stay. We hypothesize CVRD is a surrogate for autonomic nervous system dysfunction.

Grogan, Eric L.; Morris, John A.; Norris, Patrick R.; France, Daniel J.; Ozdas, Asli; Stiles, Renee A.; Harris, Paul A.; Dawant, Benoit M.; Speroff, Theodore

2004-01-01

293

Centrifugal destabilization and restabilization of plane shear flows  

SciTech Connect

The flow of an incompressible viscous fluid between parallel plates becomes unstable when the plates are tumbled. As the tumbling rate increases, the flow restabilizes. This phenomenon is elucidated by path-following techniques. The solution of the Navier-Stokes equations is approximated by spectral techniques. The linear stability of these solutions is studied.

Conley, A.J.

1997-08-01

294

Flow Rates Model  

NSDL National Science Digital Library

The Flow Rates activity is highly recommended both for math teachers and for science teachers in all fields. It can be used effectively for a variety of content applications and at various points in a course sequence. By allowing students to practice making and testing hypotheses about liquid flowing through a simple burette, it provides an excellent introduction to the scientific method. The collection and analysis of real-time data provides students with the opportunity to use their graphing and algebra skills in a real problem-solving situation. Finally, it facilitates a direct mental mapping between students' demonstration observations and mathematical modeling using STELLA software.

School, Maryland V.

295

Plasma Adiabatic Lapse Rate  

NASA Astrophysics Data System (ADS)

The plasma analog of an adiabatic lapse rate (or temperature variation with height) in atmospheric physics is obtained. A new source of plasma temperature gradient in a binary ion species mixture is found that is proportional to the concentration gradient ??? and difference in average ionization states Z2-Z1. Application to inertial-confinement-fusion implosions indicates a potentially strong effect in plastic (CH) ablators that is not modeled with mainline (single-fluid) simulations. An associated plasma thermodiffusion coefficient is derived, and charge-state diffusion in a single-species plasma is also predicted.

Amendt, Peter; Bellei, Claudio; Wilks, Scott

2012-08-01

296

Plasma adiabatic lapse rate.  

PubMed

The plasma analog of an adiabatic lapse rate (or temperature variation with height) in atmospheric physics is obtained. A new source of plasma temperature gradient in a binary ion species mixture is found that is proportional to the concentration gradient ?? and difference in average ionization states Z(2)-Z(1). Application to inertial-confinement-fusion implosions indicates a potentially strong effect in plastic (CH) ablators that is not modeled with mainline (single-fluid) simulations. An associated plasma thermodiffusion coefficient is derived, and charge-state diffusion in a single-species plasma is also predicted. PMID:23006377

Amendt, Peter; Bellei, Claudio; Wilks, Scott

2012-08-16

297

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

298

Survival Rates and Consequences  

NASA Astrophysics Data System (ADS)

To first order, the initial cluster luminosity function appears to be universal. This means that the brightest young cluster in a galaxy can be predicted from the total number of young clusters based purely on statistics. This suggests that the physical processes responsible for the formation of clusters are similar in a wide variety of galaxies, from mergers to quiescent spirals. One possibility is that conditions for making young massive clusters are globally present in mergers while only locally present in spirals (i.e., in the spiral arms). However, understanding the destruction of clusters and the accompanying survival rates is more important for understanding cluster demographics than understanding their formation. This is because only about 1 in 1,000 clusters with mass greater than 104 M? will survive to become an old globular cluster. In this paper we briefly review this basic framework and then develop a toy model that allows us to begin to address several fundamental questions. In particular, we demonstrate that young clusters in the Antennae Galaxies have a high ``infant mortality'' rate, with roughly 90 % of the clusters being destroyed each decade of log(time). We also advocate the use of an objective classification system for clusters, with the three parameters being mass, age, and size.

Whitmore, B. C.

2004-12-01

299

Measuring Your Peak Flow Rate  

MedlinePLUS

... Asthma > Taking Control of Asthma Measuring Your Peak Flow Rate A peak flow meter is a portable, inexpensive, ... for asthma management. Why Should I Measure My Flow Rate? Your peak flow rates can show you if ...

300

The Effects of Rating Purpose and Anonymity on Self Ratings.  

ERIC Educational Resources Information Center

|The present study was designed to answer four questions: (1) do anonymity and purpose affect the leniency of self ratings in general, (2) do these factors interact, (3) do self ratings approximate supervisor ratings under certain conditions, and (4) is self-assessment a useful method of determining training needs? Self-ratings and supervisory…

Arnaut, Lynn Y.; Bownas, David A.

301

Strain-rate effects for high-strain-rate computations  

NASA Astrophysics Data System (ADS)

This paper examines the effect of strain rates for computations involving high strain-rates, beyond 103 s - 1. Although it is generally agreed that there is an enhanced rate effect at these higher rates, there is uncertainty regarding the interpretation of dynamic test data, the form of the high-rate effect, and the effect of the high rates on practical problems of interest. This article provides an assessment of the high-rate effect for Taylor (cylinder impact) tests, a determination of high-rate constitutive model constants from the Taylor tests, and the effect of the high-rate response on penetration computations. The computations are performed with the Johnson-Cook constitutive model and an enhanced (high-rate) form of the Johnson-Cook model.

Johnson, G. R.; Holmquist, T. J.; Anderson, C. E., Jr.; Nicholls, A. E.

2006-08-01

302

Propandiol vapor nucleation rates  

NASA Astrophysics Data System (ADS)

Consideration of vapor-gas nucleation as binary vapor nucleation (instead widely used the one component approximation for nucleation of this system now) may lead the progress in the development of nucleation theory. Observations of phase transitions initiated by the carrier gas in the critical embryos of condensate can be a sufficiently convincing argument in this discussion. In order to confirm the role of the carrier gases received in the recent research1, in present study 1,2-propanediol and 1,3-propanediol vapor nucleation rates were measured. Carbon dioxide (Tc=304.2 K,Pc=7.39 MPa) and sulfur hexafluoride (Tc=318.7 K,Pc=3.75 MPa) were chosen as the carrier gases, because of their low and convenient critical temperatures, Tc, and critical pressures, Pc. Analysis of the experimental data shows that gas-carrier molecules are involved in new phase embryo formation. Vapor nucleation of investigated substances in a carrier gas atmosphere can be considered as nucleation of binary system. .

Anisimov, M. P.; Nasibulin, A. G.; Timoshina, L. V.; Koropchak, J. A.

2000-08-01

303

Performance Ratings and Librarians Rights  

ERIC Educational Resources Information Center

|Two aspects of rating personnel performance are explored: (1) the rating form and some guidelines for filling it in and (2) the right of the librarian who is being rated to discuss or appeal a rating he believes to be biased. (NH)|

Peele, David

1970-01-01

304

Essays on exchange rate economics  

Microsoft Academic Search

Exchange rate economics has achieved substantial development in the past few decades. Despite extensive research, a large number of unresolved problems remain in the exchange rate debate. This dissertation studied three puzzling issues aiming to improve our understanding of exchange rate behavior. Chapter Two used advanced econometric techniques to model and forecast exchange rate dynamics. Chapter Three and Chapter Four

Yan Shu

2008-01-01

305

Essays on Exchange Rate Economics  

Microsoft Academic Search

Exchange rate economics has achieved substantial development in the past few decades. Despite extensive research, a large number of unresolved problems remain in the exchange rate debate. This dissertation studied three puzzling issues aiming to improve our understanding of exchange rate behavior. Chapter Two used advanced econometric techniques to model and forecast exchange rate dynamics. Chapter Three and Chapter Four

Yan Shu

2008-01-01

306

Sequential Effects in Essay Ratings  

ERIC Educational Resources Information Center

|Contrary to previous research on sequential ratings of student performance, this study found that professional essay raters of a large-scale standardized testing program produced ratings that were drawn toward previous ratings, creating an assimilation effect. Longer intervals between the two adjacent ratings and higher degree of agreement with…

Attali, Yigal

2011-01-01

307

Publishing anonymous survey rating data  

Microsoft Academic Search

We study the challenges of protecting privacy of individuals in the large public survey rating data in this paper. Recent\\u000a study shows that personal information in supposedly anonymous movie rating records are de-identified. The survey rating data\\u000a usually contains both ratings of sensitive and non-sensitive issues. The ratings of sensitive issues involve personal privacy.\\u000a Even though the survey participants do

Xiaoxun Sun; Hua Wang; Jiuyong Li; Jian Pei

2011-01-01

308

Assessing Interest-Rate Risk from the Rate's Constituent Components  

Microsoft Academic Search

Any increase in interest rates will have implications for the Irish economy, and more specifically for the stability and soundness of the Irish financial system. The overall impact of an interest-rate rise will depend on the factors behind the increase. This paper examines some of the likely causes and consequences of an interest-rate hike. In order to understand how the

Frank Browne; Mary Everett

2005-01-01

309

Table of Exposure Rate Constants and Dose Equivalent Rate Constants.  

National Technical Information Service (NTIS)

The exposure rate constant GAMMA is calculated and tabulated for 1084 nuclides. The exposure rate constant is defined as the ratio of the product of the exposure rate and the square of the distance from a radioactive point source to the source strength Q....

B. Lauridsen

1982-01-01

310

National Utility Rate Database: Preprint  

SciTech Connect

When modeling solar energy technologies and other distributed energy systems, using high-quality expansive electricity rates is essential. The National Renewable Energy Laboratory (NREL) developed a utility rate platform for entering, storing, updating, and accessing a large collection of utility rates from around the United States. This utility rate platform lives on the Open Energy Information (OpenEI) website, OpenEI.org, allowing the data to be programmatically accessed from a web browser, using an application programming interface (API). The semantic-based utility rate platform currently has record of 1,885 utility rates and covers over 85% of the electricity consumption in the United States.

Ong, S.; McKeel, R.

2012-08-01

311

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

312

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

313

Car Depreciation (rate and slope)  

NSDL National Science Digital Library

The purpose of this activity is for students to use the concept of the rate of depreciation in a real world situation to investigate the relationship between rate and slope. Students create ordered pairs, graph depreciating car values, and calculate rates of depreciation, then identify that the rate of depreciation = slope of the line. Using the equation they then solve for future values and times.

2010-01-01

314

RATE OF CRYSTALLIZATION OF MINERALS  

Microsoft Academic Search

Determination of the growth rate of crystals may be based on knowledge of the linear rate, the volume rate, and duration of crystallization. Direct measurements are possible where crystals are in process of growth as in the laboratory, saline waters, and at volcanic gaseous exhalations. Indirect but absolute measurements are possible by relating crystal zones with known occurrences in time

D. P. Grigoryev

1961-01-01

315

Duty Cycles and Motor Rating  

Microsoft Academic Search

The horsepower rating of a motor carries a dual implication??first, torque ability; second, temperature rise. The two are frequently confused. In selecting motors for duty-cycle jobs the two concepts should be considered separately. The motor rating and type should be chosen to fit the torque requirements of the job. The proper time rating or service factor to associate with this

L. E. Hildebrand

1939-01-01

316

Paying attention to speaking rate  

Microsoft Academic Search

Variability in speaking rate results in a many-to-many mapping between acoustic properties in speech and the linguistic interpretation of an utterance. In order to recognize the phonetic structure of an utterance, listeners must calibrate their phonetic decisions against the rate at which the speech was produced. This process of rate normalization is fast and effective allowing listeners to maintain phonetic

Alexander L. Francis; Howard C. Nusbaum

1996-01-01

317

Fed to Raise Interest Rates  

NSDL National Science Digital Library

As expected, the Federal Reserve voted to raise interest rates 0.25 percent, the fifth rate raise since June. The interest rate boost is expected to help keep inflation in check during this record period (108 months) of economic expansion. Technology companies have continued to signal healthy economic growth, and unemployment rates remain low. Despite drastic price hikes in gasoline and heating oil prices, consumers are still spending. This worries economists who watched consumers pay little heed to the last four interest rate increases. The quarter point interest rate increase will average out to an extra $1 a month on consumers's credit cards, which in this period of prosperity, will not curb consumers's spending.

Missner, Emily D.

318

Heart rate and heart rate variability, a pharmacological target  

Microsoft Academic Search

Heart rate varies with respiration, blood pressure, emotion, etc., and heart rate variability (HRV) is presently one of the best indices to predict fatal issues in cardiac failure and after myocardial infarction. HRV depends on various reflexes. In addition, parallel studies of HRV and the myocardial adrenergic and muscarinic transduction system in experimental models of cardiac hypertrophy (CH) have suggested

Bernard Swynghedauw; Sylvain Jassonfl; Brigitte Chevalierfl; Jean Clairambault; Sandrine Hardouinfl; Christophe Heymesfl; Laurence Mangin; Pascale Manster; Claire Médigue; Jean-Marie Moalic; Nancy Thibault; François Carré

1997-01-01

319

Money, Interest Rates, and Exchange Rates with Endogenously Segmented Markets  

Microsoft Academic Search

We analyze the effects of money injections on interest rates and exchange rates when agents must pay a Baumol-Tobin-style fixed cost to exchange bonds and money. Asset markets are endogenously segmented because this fixed cost leads agents to trade bonds and money infrequently. When the government injects money through an open market operation, only those agents that are currently trading

Fernando Alvarez; Andrew Atkeson; Patrick J. Kehoe

2002-01-01

320

Recessions lower (some) mortality rates  

Microsoft Academic Search

In his article with the provocative title “Are Recessions Good for Your Health?”, Ruhm (J. Health Econ. 21(4) (2000) 659) has found robust and consistent evidence that the total mortality rate, age-specific mortality rates as well as most specific mortality causes are pro-cyclical. His finding that high unemployment rates are associated with lower mortality and vice versa stands in stark

Eric Neumayer

2004-01-01

321

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

322

The Type Ia Supernova Rate  

Microsoft Academic Search

We explore the idea that the Type Ia supernova (SN Ia) rate consists of two components: a prompt piece that is proportional to the star formation rate (SFR), and an extended piece that is proportional to the total stellar mass. We fit the parameters of this model to the local observations by Mannucci and collaborators and then study its impact

Evan Scannapieco; Lars Bildsten

2005-01-01

323

Evaporation rates for liquid clusters  

Microsoft Academic Search

An expression for the evaporation rate of neutral atoms from a hot liquid cluster is suggested. It combines Weisskopf's statistical model with a level density that is derived from the experimentally known free energy of a macroscopic droplet of the cluster material. For the case of sodium clusters, it is compared with the rate based on the level density of

S. Frauendorf

1995-01-01

324

Towards Smart Grid Dynamic Ratings  

NASA Astrophysics Data System (ADS)

The energy distribution industry is giving greater attention to smart grid solutions as a means for increasing the capabilities, efficiency and reliability of the electrical power network. The smart grid makes use of intelligent monitoring and control devices throughout the distribution network to report on electrical properties such as voltage, current and power, as well as raising network alarms and events. A further aspect of the smart grid embodies the dynamic rating of electrical assets of the network. This fundamentally involves a rating of the load current capacity of electrical assets including feeders, transformers and switches. The mainstream approach to rate assets is to apply the vendor plate rating, which often under utilizes assets, or in some cases over utilizes when environmental conditions reduce the effective rated capacity, potentially reducing lifetime. Using active intelligence we have developed a rating system that rates assets in real time based upon several events. This allows for a far more efficient and reliable electrical grid that is able to extend further the life and reliability of the electrical network. In this paper we describe our architecture, the observations made during development and live deployment of the solution into operation. We also illustrate how this solution blends with the smart grid by proposing a dynamic rating system for the smart grid.

Cheema, Jamal; Clark, Adrian; Kilimnik, Justin; Pavlovski, Chris; Redman, David; Vu, Maria

2011-08-01

325

Selectively Acquiring Ratings for Product  

Microsoft Academic Search

Accurate prediction of customer preferences on products is the key to any recommender systems to realize its promised strategic values such as improved customer satisfaction and therefore enhanced loyalty. In this paper, we propose proactively acquiring ratings from customers for a newly introduced product to quickly improve the accuracy of the predicted ratings generated by a collaborative filtering recommendation algorithm

326

Liquid mass flow rate computer  

Microsoft Academic Search

A flow rate computer is proposed which implements an algorithm for dividing the volumetric flow rate, measured by a turbine flow meter, into the signal from the liquid flow velocity head meter signal (the device actually measures the axial force acting upon the turbine, rather than the velocity Head). The block diagram of the device is presented and traced. The

N. N. Antov; V. A. Troynikov; V. C. Sotnikov

1985-01-01

327

Exchange Rates and Financial Fragility  

Microsoft Academic Search

In this paper we analyze three views of the relationship between the exchange rate and financial fragility: (1) the moral hazard hypothesis, according to which pegged exchange rates offer implicit insurance against exchange risk and thereby encourage reckless borrowing and lending; (2) the original sin hypothesis, which emphasizes an incompleteness in financial markets which prevents the domestic currency from being

Barry Eichengreen; Ricardo Hausmann

1999-01-01

328

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

329

Profit Rates and Intangible Capital  

Microsoft Academic Search

A central question in industrial organization is why profit rates differ so dramatically across firms and industries. One of the many explanations offered for this phenomenon is the failure of conventional accounting methods to adjust for intangible capital stocks, i.e., it is argued that profit rates do not differ dramatically when capital stocks are correctly calculated to include intangible R&D

Pamela Megna; Dennis C Mueller

1991-01-01

330

Interest rate swaps under CIR  

NASA Astrophysics Data System (ADS)

We consider fixed-for-floating interest rate swaps under the assumption that interest rates are given by the mean-reverting Cox-Ingersoll-Ross model. By using a Green's function approach, we derive analytical expressions for the values of both a vanilla swap and an in-arrears swap.

Mallier, R.; Alobaidi, G.

2004-03-01

331

Piece-Rate Incentive Schemes  

Microsoft Academic Search

This paper uses recent results from incentive theory to study heretofore informal critiques of piece-rate compensation schemes. Th e informal critiques are based on the history of failed attempts to i nstall piece-rate compensation schemes at the turn of the century. Th e formal analysis emphasizes the importance of information and commit ment in contracting. The main result is as

Robert Gibbons

1987-01-01

332

Constructing an Audience Ratings Convention  

Microsoft Academic Search

Broadcast ratings and survey forms of media research undertaken for advertisers, producers and broadcasters have been an integral part of our broadcast system for so long that it is difficult to see how much work had to go into constructing them and then having them accepted and utilised by the different industry players. Early promoters of ratings and media survey

Mark Balnaves; Tom Balnaves

2008-01-01

333

Leakage Rates for Cryolab Valves  

Microsoft Academic Search

This note summarizes a brief study on the leakage rates of cryolab valves due to the failure of the valve packings. The r gap between the shaft and the packing, the fluid (Ar or N2), the p (atm) between the fluid and atmosphere, and the initial temperature of the escaping gas were varied to determine the resulting leakage rate. The

J. M. Wendlandt

1988-01-01

334

Are evolutionary rates really variable?  

Microsoft Academic Search

Summary Langley and Fitch (1974, 1976) have shown that the pattern of nucleotide substitutions in proteins is inconsistent with a Poisson process with constant rate. From this they conclude that the rate is temporally heterogeneous. It is pointed out in this note that a process which is temporally homogeneous but not a Poisson process is compatible with the data if

John H. Gillespie; Charles H. Langley

1979-01-01

335

Heart rates during competitive orienteering  

Microsoft Academic Search

This study investigated the heart rate profiles of 16 experienced, competitive orienteers (aged 15-62 years) during three competitive events. Each competitor was assessed over three different types of course which were classified as: fast run (FR), slow run (SR) and highly physical (HP). The results showed that all subjects recorded heart rates that were between 140 and 180 beats min-1

S R Bird; R Bailey; J Lewis

1993-01-01

336

The Economics of Exchange Rates  

Microsoft Academic Search

Reviews the literature on exchange rate economics over the last two decades, with particular reference to recent developments. Topics surveyed include the evidence on foreign exchange market efficiency and forward discount bias, chewed interest parity and purchasing power parity, the theory and evidence relating to the determination of exchange rates (the flexible-price monetary model, the stickyprice monetary model, the equilibrium

Mark P. Taylor

1995-01-01

337

Flexible Exchange Rates and Interdependence  

Microsoft Academic Search

The paper was prepared for the NBER-IMF conference on Exchange Rate Policy and Interdependence. It reviews the experience with flexible exchange rates and the main policy alternatives that have been suggested. The theoretical part develops a modern open economy macro model with an emphasis on capital mobility, real and nominal wage stickiness and expectations. The impact of disturbances is discussed

Rudiger Dornbusch

1983-01-01

338

Rating scales and Rasch measurement.  

PubMed

Assessments with ratings in ordered categories have become ubiquitous in health, biological and social sciences. Ratings are used when a measuring instrument of the kind found in the natural sciences is not available to assess some property in terms of degree - for example, greater or smaller, better or worse, or stronger or weaker. The handling of ratings has ranged from the very elementary to the highly sophisticated. In an elementary form, and assumed in classical test theory, the ratings are scored with successive integers and treated as measurements; in a sophisticated form, and used in modern test theory, the ratings are characterized by probabilistic response models with parameters for persons and the rating categories. Within modern test theory, two paradigms, similar in many details but incompatible on crucial points, have emerged. For the purposes of this article, these are termed the statistical modeling and experimental measurement paradigms. Rather than reviewing a compendium of available methods and models for analyzing ratings in detail, the article focuses on the incompatible differences between these two paradigms, with implications for choice of model and inferences. It shows that the differences have implications for different roles for substantive researchers and psychometricians in designing instruments with rating scales. To illustrate these differences, an example is provided. PMID:21958102

Andrich, David

2011-10-01

339

Increasing undergraduate student retention rates  

Microsoft Academic Search

Based on data from a questionnaire survey of the new undergraduate intake to the University of Birmingham, the factors which influence withdrawal\\/retention rates in the first term were examined. The effectiveness of counselling intervention with first-year undergraduate students at risk of leaving university in their first term is also explored. The implications for universities wishing to increase retention rates and

Barbara Rickinson; Desmond Rutherford

1995-01-01

340

Relation between electrostatic discharge rate and outgassing rate  

SciTech Connect

This paper reports on sections of solar panel and reflector charged in a 25-keV electron beam. The measured outgassing and discharge rates varied coincidentally, indicating that outgassing is a contributing cause of discharges.

Bogorad, A.; Bowman, C. (GE Astro-Space Div., Princetown, NJ (US)); Lowman, J.; Bouknight, R.; Armenti, J., Lloyd, T. (GE Astro-Space Div., Philadelphia, PA (US))

1989-12-01

341

Relation between electrostatic discharge rate and outgassing rate  

Microsoft Academic Search

This paper reports on sections of solar panel and reflector charged in a 25-keV electron beam. The measured outgassing and discharge rates varied coincidentally, indicating that outgassing is a contributing cause of discharges.

A. Bogorad; C. Bowman; J. Lowman; R. Bouknight; J. Armenti; T. Lloyd

1989-01-01

342

Growth rate of Escherichia coli.  

PubMed Central

It should be possible to predict the rate of growth of Escherichia coli of a given genotype in a specified environment. The idea that the rate of synthesis of ATP determines the rate of growth and that the yield of ATP determines the yield of growth is entrenched in bacterial physiology, yet this idea is inconsistent with experimental results. In minimal media the growth rate and yield vary with the carbon source in a manner independent of the rate of formation and yield of ATP. With acetate as the carbon source, anapleurotic reactions, not ATP synthesis, limit the growth rate. For acetate and other gluconeogenic substrates the limiting step appears to be the formation of triose phosphate. I conclude that the rate of growth is controlled by the rate of formation of a precursor metabolite and, thus, of monomers such as amino acids derived from it. The protein-synthesizing system is regulated according to demand for protein synthesis. I examine the conjecture that the signal for this regulation is the ratio of uncharged tRNA to aminoacyl-tRNA, that this signal controls the concentration of guanosine tetraphosphate, and that the concentration of guanosine tetraphosphate controls transcription of rrn genes. Differential equations describing this system were solved numerically for steady states of growth; the computed values of ribosomes and guanosine tetraphosphate and the maximal growth rate agree with experimental values obtained from the literature of the past 35 years. These equations were also solved for dynamical states corresponding to nutritional shifts up and down.

Marr, A G

1991-01-01

343

Prevalence of father-child rough-and-tumble play and physical aggression in preschool children  

Microsoft Academic Search

Three samples of francophone subjects from Quebec (Canada) are used to establish the prevalence of parent-child RTP according\\u000a to different personal, social and family variables, and to verify if children who engage in more RTP with their father exhibit\\u000a less physical aggression towards other children and are more competitive without resorting to aggression. Our results showed\\u000a that 24 to 43%

Daniel Paquette; René Carbonneau; Diane Dubeau; Marc Bigras; Richard E. Tremblay

2003-01-01

344

Tumbling 'Component Walls' in Contingency Operations: A Trumpet's Blare for Sanding Joint Task Force Headquarters.  

National Technical Information Service (NTIS)

The principle aim of this study is to determine if further unification of service components below the combatant CINC level is required. More specifically, do the combatant CINC's require a standing joint task force (JTF) headquarters to provide operation...

J. C. Coleman

1991-01-01

345

Flapping, ratcheting, bursting, and tumbling: A selection of problems in fluid-body interaction dynamics  

NASA Astrophysics Data System (ADS)

The dynamics of bodies immersed in fluids is a subject of great practical and biological interest. Fluid-body interaction systems are ubiquitous, ranging from large scale applications like swimming and flying, to more recent work on micro-scale biofluiddynamics. We consider a selection of fluid-body interactions, employing numerical methods in order to deduce their salient features. This work is separated into two parts, each focusing on problems in one of two fluid regimes: the intermediate Reynolds number regime, where inertia and viscous dissipation are both important, and the low Reynolds number regime, where viscous dissipation dominates inertial effects. First, in order to understand the role of flexibility in flapping flight, we analyze a heaving wing system with passive pitching. We reproduce qualitatively the results of recent experiments: we find flapping frequencies corresponding to very efficient locomotion, a regime of under-performance compared to a rigid wing, and a bi-stable regime where the flapping wing can move horizontally in either direction. We find that a particular phase relationship corresponds to this direction reversal, and we consider the importance of various dimensionless parameters. Subsequently, we examine a fluid-ratchet mechanism that is exhibited by a shape-changing body in an oscillating fluid. We find that such a body can maintain its altitude, or even ascend, against a gravitational force. Other related phenomena are also considered. In the second section, we begin by studying a special sedimentation phenomenon in a highly viscous fluid. We find that a periodic sedimentation orbit may be experienced by two identical settling bodies. We consider numerically the stability of these orbits, and we show that free-surface effects are likely responsible for body collisions observed in a related experiment. In addition, we find that a similar orbit for three bodies is unstable, and uncover other, new types of periodic sedimentation dynamics. We conclude with a brief introduction to a novel form of locomotion at the micro-scale, a special form of locomotion involving a re-hinging body with only two links at low Reynolds number, in a variation on Purcell's three-link swimmer.

Spagnolie, Saverio E.

346

Military's Modernization Crisis - Modernization Funding Must Be Increased, While the Defense Budget Tumbles.  

National Technical Information Service (NTIS)

Over the years, cuts in the defense budget have had a significant impact on the modernization of our military forces. This study explores the nature of the defense cuts, what impact they have had and what changes may be made. It argues that while the defe...

G. H. Swanson

1996-01-01

347

Multigeneration Cross Contamination of Mail with Bacillus Species Spores by Tumbling ?  

PubMed Central

In 2001, envelopes loaded with Bacillus anthracis spores were mailed to Senators Daschle and Leahy as well as to the New York Post and NBC News buildings. Additional letters may have been mailed to other news agencies because there was confirmed anthrax infection of employees at these locations. These events heightened the awareness of the lack of understanding of the mechanism(s) by which objects contaminated with a biological agent might spread disease. This understanding is crucial for the estimation of the potential for exposure to ensure the appropriate response in the event of future attacks. In this study, equipment to simulate interactions between envelopes and procedures to analyze the spread of spores from a “payload” envelope (i.e., loaded internally with a powdered spore preparation) onto neighboring envelopes were developed. Another process to determine whether an aerosol could be generated by opening contaminated envelopes was developed. Subsequent generations of contaminated envelopes originating from a single payload envelope showed a consistent two-log decrease in the number of spores transferred from one generation to the next. Opening a tertiary contaminated envelope resulted in an aerosol containing 103 B. anthracis spores. We developed a procedure for sampling contaminated letters by a nondestructive method aimed at providing information useful for consequence management while preserving the integrity of objects contaminated during the incident and preserving evidence for law enforcement agencies.

Edmonds, Jason; Clark, Paul; Williams, Leslie; Lindquist, H. D. Alan; Martinez, Kenneth; Gardner, Warren; Shadomy, Sean; Hornsby-Myers, Jennifer

2010-01-01

348

Multigeneration cross contamination of mail with Bacillus species spores by tumbling.  

PubMed

In 2001, envelopes loaded with Bacillus anthracis spores were mailed to Senators Daschle and Leahy as well as to the New York Post and NBC News buildings. Additional letters may have been mailed to other news agencies because there was confirmed anthrax infection of employees at these locations. These events heightened the awareness of the lack of understanding of the mechanism(s) by which objects contaminated with a biological agent might spread disease. This understanding is crucial for the estimation of the potential for exposure to ensure the appropriate response in the event of future attacks. In this study, equipment to simulate interactions between envelopes and procedures to analyze the spread of spores from a "payload" envelope (i.e., loaded internally with a powdered spore preparation) onto neighboring envelopes were developed. Another process to determine whether an aerosol could be generated by opening contaminated envelopes was developed. Subsequent generations of contaminated envelopes originating from a single payload envelope showed a consistent two-log decrease in the number of spores transferred from one generation to the next. Opening a tertiary contaminated envelope resulted in an aerosol containing 10(3) B. anthracis spores. We developed a procedure for sampling contaminated letters by a nondestructive method aimed at providing information useful for consequence management while preserving the integrity of objects contaminated during the incident and preserving evidence for law enforcement agencies. PMID:20511424

Edmonds, Jason; Clark, Paul; Williams, Leslie; Lindquist, H D Alan; Martinez, Kenneth; Gardner, Warren; Shadomy, Sean; Hornsby-Myers, Jennifer

2010-05-28

349

Predicting the rotational tumbling of dynamic multidomain proteins and supramolecular complexes.  

PubMed

Time is of the essence: The rotational motion of biomolecules depends on intra- and intermolecular interactions and thus on distinct functional states. A new method, called HYCUD accurately predicts rotational correlation times in complex dynamic systems. It gives insights into the motional behavior of multidomain proteins in their free form and in supramolecular complexes. PMID:24000220

Rezaei-Ghaleh, Nasrollah; Klama, Frederik; Munari, Francesca; Zweckstetter, Markus

2013-09-02

350

And it all came tumbling down...new industrial relations legislation to hurt nurses.  

PubMed

When the Howard Government gains total control of Parliament in July this year, it has announced it will introduce legislation which will dismantle Australia's industrial relations system. The Australian Nursing Federation (ANF) and the Queensland Nurses' Union (QNU) expect the new legislation will reduce the role of unions, put downward pressure on wages and conditions and dilute the power of the Australian Industrial Relations Commission (AIRC) to hear and resolve disputes. The changes will not only affect nurses' wages and conditions, but threaten to undermine the profession itself. PMID:16035519

351

Fear of injury in gymnastics: self-efficacy and psychological strategies to keep on tumbling.  

PubMed

The aim of this study was to examine female gymnasts' fear of injury, their sources of self-efficacy and the psychological strategies used to overcome their fears. The participants were 10 female gymnasts aged 12 - 17 years. They had all taken part in competitive gymnastics and had experienced some type of injury during their careers. Individual interviews were conducted using a structured interview guide. Data were analysed using an inductive content analysis. The results indicated that gymnasts were most fearful of injuries because of the difficulty in returning from an injury and being unable to participate in practices and competitions while injured. Gymnasts described aspects of their past performance experience, such as success, consistency and communication with significant others, as important sources of self-efficacy. Some examples of psychological strategies used to overcome their fear of injury were mental preparation (e.g. imagery, relaxation), just "going for a skill" and the coaches' influence. PMID:16194995

Chase, Melissa A; Magyar, Michelle T; Drake, Brent M

2005-05-01

352

Effects of neonatal handling and maternal separation on rough-and-tumble play in the rat.  

PubMed

The extent to which brief daily handling and longer periods of separation from the mother during the first 2 weeks of life can affect play behavior in juvenile rats was assessed. Rat pups were separated from the mother for either 15 min daily (handling) or for 3 hr daily (maternal separation), and play was observed as juveniles. Overall levels of playfulness were not affected by either manipulation, although certain aspects of playful responsiveness were affected in males, but not females. In particular, the pattern of responsiveness to playful contacts was feminized in both handled and separated male rats. Activity in a novel open field at 15 days of age was increased in both males and females from the separated group, but not in the handled animals, as were the number of rears exhibited during the play bouts. These data suggest that early rearing experiences can have subtle gender-dependent effects on some aspects of play in juvenile rats and that the underlying mechanism(s) responsible for these effects may differ from those associated with other effects reported for handling and maternal separation. PMID:12325135

Arnold, Jennifer L; Siviy, Stephen M

2002-11-01

353

Learning to teach science as inquiry in the rough and tumble of practice  

Microsoft Academic Search

This study examined the knowledge, beliefs and efforts of five prospective teachers to enact teaching science as inquiry, over the course of a one-year high school fieldwork experience. Data sources included interviews, field notes, and artifacts, as these prospective teachers engaged in learning how to teach science. Research questions included 1) What were these prospective teachers' beliefs of teaching science?

Barbara A. Crawford

2007-01-01

354

Comment on ``Tank-treading and tumbling frequencies of capsules and red blood cells''  

NASA Astrophysics Data System (ADS)

In a recent computational investigation, Yazdani [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.046305 83, 046305 (2011)] reported an exponential (logarithmic) dependence of the tank-treading frequency Ftt with the viscosity ratio ? at low (moderate) viscosity ratios for erythrocytes in shear flows. We argue that the authors misinterpreted the inverse linear dependence on ? of the tank-treading frequency Ftt, as found by Wodson and Dimitrakopoulos [Biophys. J.BIOJAU0006-349510.1016/j.bpj.2010.08.048 99, 2906 (2010)], owing to the fact that Yazdani plotted their frequency-versus-? results in a log-log plot.

Dimitrakopoulos, P.

2011-11-01

355

Chlamydomonas Swims with Two ``Gears'' in a Eukaryotic Version of Run-and-Tumble Locomotion  

Microsoft Academic Search

The coordination of eukaryotic flagella is essential for many of the most basic processes of life (motility, sensing, and development), yet its emergence and regulation and its connection to locomotion are poorly understood. Previous studies show that the unicellular alga Chlamydomonas, widely regarded as an ideal system in which to study flagellar biology, swims forward by the synchronous action of

Marco Polin; Idan Tuval; Knut Drescher; J. P. Gollub; Raymond E. Goldstein

2009-01-01

356

Quantifying the sorting efficiency of self-propelled run-and-tumble swimmers by geometrical ratchets  

NASA Astrophysics Data System (ADS)

Suitable asymmetric microstructures can be used to control the direction of motion in microorganism populations. This rectification process makes it possible to accumulate swimmers in a region of space or to sort different swimmers. Here we study numerically how the separation process depends on the specific motility strategies of the microorganisms involved. Crucial properties such as the separation efficiency and the separation time for two bacterial strains are precisely defined and evaluated. In particular, the sorting of two bacterial populations inoculated in a box consisting of a series of chambers separated by columns of asymmetric obstacles is investigated. We show how the sorting efficiency is enhanced by these obstacles and conclude that this kind of sorting can be efficiently used even when the involved populations differ only in one aspect of their swimming strategy.

Berdakin, Iván; Silhanek, Alejandro V.; Moyano Cortéz, Hernán N.; Marconi, Verónica I.; Condat, Carlos A.

2013-10-01

357

Prevalence of Father-Child Rough-and-Tumble Play and Physical Aggression in Preschool Children  

ERIC Educational Resources Information Center

|Three samples of francophone subjects from Quebec (Canada) are used to establish the prevalence of parent-child RTP according to different personal, social and family variables, and to verify if children who engage in more RTP with their father exhibit less physical aggression towards other children and are more competitive without resorting to…

Paquette, Daniel; Carbonneau, Rene; Dubeau, Diane; Bigras, Marc; Tremblay, Richard E.

2003-01-01

358

Hysteresis in transition between individual and collective behavior in suspension of swimming bacteria  

NASA Astrophysics Data System (ADS)

We present a new method for control of motility and tumbling rate of swimming bacteria Bacillus Subtilis via precise and rapid control of temperature of the bacterial suspension. Transitions between individual and collective behaviors in a response to cyclical temperature change in a range of temperatures between 5C and 35C with the rates from 0.1C/s to 1C/s were investigated. Temperature decrease typically results in a decrease of bacterial motility while preserving low tumbling rates. The temperature increase above 20C triggers a ``heat shock'': a significant jump in tumbling rate resulting in temporal decrease of the average swimming speed and termination of collective motion. At temperatures below 20C due to relative low tumbling rates we discovered a hysteresis in the transition between individual and collective swimming: velocity correlation length vs. average swimming speed of bacteria exhibits hysteric behavior.

Sokolov, Andrey; Aranson, Igor

2013-03-01

359

Clearing up Homicide Clearance Rates.  

National Technical Information Service (NTIS)

Law enforcement's ability to make arrests following crimes appears to have significantly diminished in recent years. This is especially true for homicide: From 1980 to 1996, the rate at which homicide cases were cleared nationally decreased more than 7 pe...

C. Wellford J. Cronin

2008-01-01

360

High Repetition Rate Chemical Laser.  

National Technical Information Service (NTIS)

A hydrogen fluoride (HF) chemical laser with an active medium 10 cm in length was constructed for operation at high pulse repetition rates using transverse excitation. The device employed 29 resistively loaded electrodes; open-cycle operation was achieved...

T. V. Jacobson G. H. Kimbell A. R. Lambert D. R. Snelling

1973-01-01

361

Nucleation rate for black holes  

NASA Astrophysics Data System (ADS)

A simple heuristic calculation is given for the rate of nucleation of black holes at positive temperature. This calculation is based on the classical theory of nucleation and reproduces the result of Gross, Perry, and Yaffe.

Kapusta, Joseph I.

1984-08-01

362

Reconnection Rates of Magnetic Fields.  

National Technical Information Service (NTIS)

The Sweet-Parker and Petschek scalings of magnetic reconnection rate are modified to include the effect of the viscosity. The modified scalings show that the viscous effect can be important in high- beta plasmas. The theoretical reconnection scalings are ...

W. Park D. A. Monticello R. B. White

1983-01-01

363

DEMOS for RELATED RATE Problems  

NSDL National Science Digital Library

This demo provides a toolbox of visual aids that illustrate fundamental concepts for understanding and developing equations that model related rate problems. A gallery of animations for various problems is included.

Roberts, Lila F.; Hill, David R.

2002-02-11

364

Cooling Rates in Splat Cooling.  

National Technical Information Service (NTIS)

Calculations and experimental observations made on cooling rates during splat quenching are presented. Three possible types of cooling behavior are discussed: ideal cooling, intermediate cooling, and Newtonian cooling. The effects of splatting-process var...

R. C. Ruhl

1966-01-01

365

Death Rates - State Cancer Profiles  

Cancer.gov

Profiles Home > Death Rates Area: US by State Alabama Counties Alaska Counties Arizona Counties Arkansas Counties California Counties Colorado Counties Connecticut Counties Delaware Counties District of Columbia Florida Counties Georgia Counties Hawaii

366

Solid Propellant Burning Rate Detector.  

National Technical Information Service (NTIS)

The instrument measures accurately the burning rate of solid propellant rocket motors. This is accomplished by use of light-transmitting rods of different lengths embedded in a propellant grain and transmitting light energy during burning of the grain to ...

J. E. Fitzgerald N. C. Allen

1965-01-01

367

High-Redshift Supernova Rates  

Microsoft Academic Search

We use a sample of 42 supernovae detected with the Advanced Camera for Surveys on board the Hubble Space Telescope as part of the Great Observatories Origins Deep Survey to measure the rate of core-collapse supernovae to z~0.7 and Type Ia supernovae to z~1.6. This significantly increases the redshift range at which supernova rates have been estimated from observations. The

Tomas Dahlen; Louis-Gregory Strolger; Adam G. Riess; Bahram Mobasher; Ranga-Ram Chary; Christopher J. Conselice; Andrew S. Fruchter; Mauro Giavalisco; Mario Livio; Piero Madau; Nino Panagia; John L. Tonry

2004-01-01

368

Endoscopic Cubital Tunnel Recurrence Rates  

Microsoft Academic Search

Cubital tunnel syndrome is the second most common nerve entrapment in the upper extremity. There are no current publications\\u000a concerning the recurrence rates after endoscopic cubital tunnel release. The purpose of this study is to evaluate the recurrence\\u000a rate of endoscopic cubital tunnel release compared to published reports of recurrence following open cubital tunnel procedures.\\u000a We reviewed 134 consecutive cases

Tyson K. Cobb; Patrick T. Sterbank; Jon H. Lemke

2010-01-01

369

Heart rate variability: a review  

Microsoft Academic Search

Heart rate variability (HRV) is a reliable reflection of the many physiological factors modulating the normal rhythm of the\\u000a heart. In fact, they provide a powerful means of observing the interplay between the sympathetic and parasympathetic nervous\\u000a systems. It shows that the structure generating the signal is not only simply linear, but also involves nonlinear contributions.\\u000a Heart rate (HR) is

U. Rajendra Acharya; Paul K. Joseph; N. Kannathal; Choo Min Lim; Jasjit S. Suri

2006-01-01

370

An interest rates cluster analysis  

NASA Astrophysics Data System (ADS)

An empirical analysis of interest rates in money and capital markets is performed. We investigate a set of 34 different weekly interest rate time series during a time period of 16 years between 1982 and 1997. Our study is focused on the collective behavior of the stochastic fluctuations of these time series which is investigated by using a clustering linkage procedure. Without any a priori assumption, we individuate a meaningful separation in 6 main clusters organized in a hierarchical structure.

di Matteo, T.; Aste, T.; Mantegna, R. N.

2004-08-01

371

Strain Rates and Material Spins  

Microsoft Academic Search

The material time rate of Lagrangean strain measures, objective corotational rates of Eulerian strain measures and their defining\\u000a spin tensors are investigated from a general point of view. First, a direct and rigorous method is used to derive a simple\\u000a formula for the gradient of the tensor-valued function defining a general class of strain measures. By means of this formula

Heng Xiao; Otto Timme Bruhns; Albert Thomas Marie Meyers

1998-01-01

372

Microfluidic Devices and Flow Rate  

NSDL National Science Digital Library

Students obtain a basic understanding of microfluidic devices, how they are developed and their uses in the medical field. After conducting the associated activity, they watch a video clip and learn about flow rate and how this relates to the speed at which medicine takes effect in the body. What they learn contributes to their ongoing objective to answer the challenge question presented in lesson 1 of this unit. They conclude by solving flow rate problems provided on a worksheet.

Vu Bioengineering Ret Program

373

Evaporation rate of nucleating clusters.  

PubMed

The Becker-Döring kinetic scheme is the most frequently used approach to vapor liquid nucleation. In the present study it has been extended so that master equations for all cluster configurations are included into consideration. In the Becker-Döring kinetic scheme the nucleation rate is calculated through comparison of the balanced steady state and unbalanced steady state solutions of the set of kinetic equations. It is usually assumed that the balanced steady state produces equilibrium cluster distribution, and the evaporation rates are identical in the balanced and unbalanced steady state cases. In the present study we have shown that the evaporation rates are not identical in the equilibrium and unbalanced steady state cases. The evaporation rate depends on the number of clusters at the limit of the cluster definition. We have shown that the ratio of the number of n-clusters at the limit of the cluster definition to the total number of n-clusters is different in equilibrium and unbalanced steady state cases. This causes difference in evaporation rates for these cases and results in a correction factor to the nucleation rate. According to rough estimation it is 10(-1) by the order of magnitude and can be lower if carrier gas effectively equilibrates the clusters. The developed approach allows one to refine the correction factor with Monte Carlo and molecular dynamic simulations. PMID:22112089

Zapadinsky, Evgeni

2011-11-21

374

Sensors for rate responsive pacing  

PubMed Central

Advances in pacemaker technology in the 1980s have generated a wide variety of complex multiprogrammable pacemakers and pacing modes. The aim of the present review is to address the different rate responsive pacing modalities presently available in respect to physiological situations and pathological conditions. Rate adaptive pacing has been shown to improve exercise capacity in patients with chronotropic incompetence. A number of activity and metabolic sensors have been proposed and used for rate control. However, all sensors used to optimize pacing rate metabolic demands show typical limitations. To overcome these weaknesses the use of two sensors has been proposed. Indeed an unspecific but fast reacting sensor is combined with a more specific but slower metabolic one. Clinical studies have demonstrated that this methodology is suitable to reproduce normal sinus behavior during different types and loads of exercise. Sensor combinations require adequate sensor blending and cross checking possibly controlled by automatic algorithms for sensors optimization and simplicity of programming. Assessment and possibly deactivation of some automatic functions should be also possible to maximize benefits from the dual sensor system in particular conditions. This is of special relevance in patient whose myocardial contractility is limited such as in subjects with implantable defibrillators and biventricular pacemakers. The concept of closed loop pacing, implementing a negative feedback relating pacing rate and the control signal, will provide new opportunities to optimize dual-sensors system and deserves further investigation. The integration of rate adaptive pacing into defibrillators is the natural consequence of technical evolution.

Dell'Orto, Simonetta; Valli, Paolo; Greco, Enrico Maria

2004-01-01

375

Homogeneous nucleation rates for water  

NASA Astrophysics Data System (ADS)

Homogeneous nucleation rates of light (H2O) and heavy (D2O) water have been measured under identical conditions. Comparing the nucleation rates for H2O and D2O at the same respective vapor pressure pv and temperature T the rates differ by a factor of 2500. However, the individual data points superimpose, if compared at the same supersaturation, i.e., they are the same within experimental scatter. Onset supersaturations S0 for H2O at nucleation rates of J0=107 cm-3 s-1 compared with previous measurements by Viisanen et al.(Viisanen, Y., Strey, R., and Reiss, H., J. Chem. Phys., 99, 4680 (1993); Erratum: Viisanen, Y., Strey, R., and Reiss, H., J. Chem. Phys., (2000) in press) show fair agreement. Predictions by the classical nucleation theory-using the most recent expressions for temperature-dependent vapor pressure, surface tension and density-are compared to the experimental data. While the predictions correctly yield the slope of the experimental nucleation rate curves and for one temperature (for H2O T=240 K) even the correct absolute rate, the temperature dependence is experimentally shown to be weaker. .

Wölk, Judith; Viisanen, Yrjö; Strey, Reinhard

2000-08-01

376

Stroke Rates: 1980-2000  

PubMed Central

In this paper, the authors report trends in hospitalized stroke rates among Minneapolis-St. Paul, Minnesota (population 2.6 million) metropolitan area residents aged 30–74 years from 1980 to 2000. Cases were identified from lists of discharge diagnoses provided by hospitals serving the target population. Age-adjusted, sex-specific stroke attack rates were computed for each survey year by using 5 different diagnostic definitions: 2 based purely on International Classification of Diseases, Ninth Revision (ICD-9) codes and 3 including clinical and neuroimaging criteria. Stroke rates, as measured by a highly specific clinical definition, remained stable from 1980 to 2000 for women. For men, these rates declined modestly from 1980 to 1990 and leveled off during 1990–2000. In contrast, use of stroke-related ICD-9 discharge codes declined significantly from 1980 to 2000: 35% among men and 16% among women. Neuroimaging use increased significantly from 75% of cases in 1980 to 98% in 2000. Short-term (28-day) stroke survival improved significantly, by 16% for women and 12% for men, from 1980 to 2000. The decline in stroke ICD-9 code usage reflects the influence of increased neuroimaging on discharge coding. The improved short-term survival in the face of stable, clinically defined stroke rates may imply treatment advances or ascertainment of less severe strokes, possibly masking a true decline in stroke rates.

Anderson, David C.; Jacobs, David R.; Barber, Cheryl A.; Luepker, Russell V.

2009-01-01

377

Coal Transportation Rate Sensitivity Analysis  

EIA Publications

On December 21, 2004, the Surface Transportation Board (STB) requested that the Energy Information Administration (EIA) analyze the impact of changes in coal transportation rates on projected levels of electric power sector energy use and emissions.Specifically, the STB requested an analysis of changes in national and regional coalconsumption and emissions resulting from adjustments in railroad transportation rates for Wyoming's Powder River Basin (PRB) coal using the National Energy Modeling System(NEMS). However, because NEMS operates at a relatively aggregate regional level and does not represent the costs of transporting coal over specific rail lines, this analysis reports on the impacts of interregional changes in transportation rates from those used in the Annual Energy Outlook 2005 (AEO2005) reference case.

John Conti

2005-04-01

378

Injury rates in Shotokan karate  

PubMed Central

OBJECTIVE: To document the injury rate in three British Shotokan karate championships in consecutive years. In these tournaments strict rules governed contact, with only "light" or "touch" contact allowed. Protective padding for the head, hands, or feet was prohibited. METHODS: Prospective recording of injuries resulting from 1770 bouts in three national competitions of 1996, 1997, and 1998. Details of ages and years of karate experience were also obtained. RESULTS: 160 injuries were sustained in 1770 bouts. The overall rate of injury was 0.09 per bout and 0.13 per competitor. 91 (57%) injuries were to the head. The average age of those injured was 22 years, with an average of nine years of experience in karate. CONCLUSIONS: The absence of protective padding does not result in higher injury rates than in most other series of Shotokan karate injuries. Strict refereeing is essential, however, to maintain control and minimise contact. ???

Critchley, G. R.; Mannion, S.; Meredith, C.

1999-01-01

379

[Morbidity rates in university students].  

PubMed

The current higher education modernization is accompanied by the intensification of an educational process. Due to intensive mental work and a need to adapt to new educational conditions, the students belong to a group of increased risk. Morbidity rates were studied in medical students during education. The study indicated a rise in morbidity in the period 2005 to 2009, high morbidity rates in first- and second-year students, the seasonal pattern of diseases, and a preponderance of respiratory diseases and mental disorders as a ground for a sabbatical leave, which is due to the specific features of education at a medical higher educational establishment. PMID:21899104

Kozhevnikova, N G

380

Rate Change Big Bang Theory  

NASA Astrophysics Data System (ADS)

The Rate Change Big Bang Theory redefines the birth of the universe with a dramatic shift in energy direction and a new vision of the first moments. With rate change graph technology (RCGT) we can look back 13.7 billion years and experience every step of the big bang through geometrical intersection technology. The analysis of the Big Bang includes a visualization of the first objects, their properties, the astounding event that created space and time as well as a solution to the mystery of anti-matter.

Strickland, Ken

2013-04-01

381

7 CFR 1714.5 - Determination of interest rates on municipal rate loans.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Determination of interest rates on municipal rate loans. 1714... § 1714.5 Determination of interest rates on municipal rate loans. ...Program HomePage, a schedule of interest rates for municipal rate loans...

2010-01-01

382

7 CFR 1714.5 - Determination of interest rates on municipal rate loans.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Determination of interest rates on municipal rate loans. 1714... § 1714.5 Determination of interest rates on municipal rate loans. ...Program HomePage, a schedule of interest rates for municipal rate loans...

2009-01-01

383

Exchange Rates and Old People.  

ERIC Educational Resources Information Center

|Extends earlier work on aging as a process of exchange by focusing on the issue of exchange rates and how they are negotiated. Access to power resources declines with age, placing the old person in the position of negotiating from weakness. (Author)|

Dowd, James J.

1980-01-01

384

Cohort Default Rates in Context  

ERIC Educational Resources Information Center

|Burgeoning student loan debt indicates problems not only for the country's borrowers but also for the postsecondary system. The rise in student loan defaults signifies a rise in institutional cohort default rates (CDRs)--a measure of accountability that informs the government and the general public how well an institution prepares its students…

Looney, Shannon M.

2011-01-01

385

Fast repetition rate (FRR) flasher  

DOEpatents

A fast repetition rate (FRR) flasher is described suitable for high flash photolysis including kinetic chemical and biological analysis. The flasher includes a power supply, a discharge capacitor operably connected to be charged by the power supply, and a flash lamp for producing a series of flashes in response to discharge of the discharge capacitor. A triggering circuit operably connected to the flash lamp initially ionizes the flash lamp. A current switch is operably connected between the flash lamp and the discharge capacitor. The current switch has at least one insulated gate bipolar transistor for switching current that is operable to initiate a controllable discharge of the discharge capacitor through the flash lamp. Control means connected to the current switch for controlling the rate of discharge of the discharge capacitor thereby to effectively keep the flash lamp in an ionized state between successive discharges of the discharge capacitor. Advantageously, the control means is operable to discharge the discharge capacitor at a rate greater than 10,000 Hz and even up to a rate greater than about 250,000 Hz. 14 figs.

Kolber, Z.; Falkowski, P.

1997-02-11

386

Fed Leaves Interest Rates Alone  

NSDL National Science Digital Library

This week's In the News looks at the recent Federal Reserve Board decision to leave interest rates unchanged. The eight resources discussed provide background information on interest rates and inflation, Federal Reserve news, and current US economic data. With the stock market at record highs and global economic crises fading, the Federal Reserve Board (FRB) showed increased concern about the risk of inflation this month at a May 18, 1999 meeting of the Federal Open Market Committee (FOMC). Although committee members ultimately decided not to raise the rate at which banks lend to each other, they cited a "tight" domestic labor market and "ongoing strength in demand in excess of productivity gains" as possible reasons for future rate hikes. Wall Street reacted to the Fed news with a 100 point Dow Jones Industrial Average fall on May 18 but recovered by the end of the day down just 16.52, and many market watchers expressed optimism over the FOMC action. Irwin Kellner, chief economist at CBS.MarketWatch.com, for example, deemed the decision "great" and praised the Fed for a flexible policy that is not locked into a particular course of action should the economy change unexpectedly.

Waters, Megan.

387

PBXN-110 Burn Rate Estimate.  

National Technical Information Service (NTIS)

It is estimated that PBXN-110 will burn laminarly with a burn function of B = (0.6-1.3)*P(sup 1.0) (B is the burn rate in mm/s and P is pressure in MPa). This paper provides a brief discussion of how this burn behavior was estimated.

E. Glascoe

2008-01-01

388

PBXN-110 Burn Rate Estimate  

SciTech Connect

It is estimated that PBXN-110 will burn laminarly with a burn function of B = (0.6-1.3)*P{sup 1.0} (B is the burn rate in mm/s and P is pressure in MPa). This paper provides a brief discussion of how this burn behavior was estimated.

Glascoe, E

2008-08-11

389

Evaluating Ratings on Bidirectional Scales.  

ERIC Educational Resources Information Center

Procedures are described for determining the statistical significance of a set of ratings made on bidirectional (B) scales. B and its statistical significance can be determined on samples of items or raters. The statistical significance of a mean of B values can be assessed by applying a normal approximation test. (Author/DWH)

Aiken, Lewis R.

1985-01-01

390

Reconnection rates of magnetic fields  

Microsoft Academic Search

The Sweet-Parker and Petschek scalings of magnetic reconnection rate are modified to include the effect of the viscosity. The modified scalings show that the viscous effect can be important in high-..beta.. plasmas. The theoretical reconnection scalings are compared with numerical simulation results in a tokamak geometry for three different cases: a forced reconnection driven by external coils, the nonlinear m

D. A. Monticello; R. B. White

1983-01-01

391

Precise, Facile Initial Rate Measurements†  

PubMed Central

Progress curve analysis has been used sparingly in studies of enzyme-catalyzed reactions due largely to the complexity of the integrated rate expressions used in data analysis. Using an experimental design that simplifies the analysis, the advantages and limitations of progress curve experiments are explored in a study of four different enzyme-catalyzed reactions. The approach involves relatively simple protocols, requires 20–25% of the materials, and provides 10- to 20-fold signal enhancements compared to analogous initial rate studies. Product inhibition, which complicates integrated rate analysis, was circumvented using cloned, purified enzymes that remove the products and draw the reaction forward. The resulting progress curves can be transformed into the equivalent of thousands of initial rate and [S] measurements and, due to the absence of product inhibition, are plotted in the familiar, linear double-reciprocal format. Allowing product to accumulate during a reaction produces a continuously changing substrate/product ratio that can be used as the basis for obtaining product inhibition constants and to distinguish among the three classical inhibition mechanisms. Algebraic models describing the double-reciprocal patterns obtained from such inhibition studies are presented. The virtual continuum of substrate concentrations that occurs during a progress curve experiment provides a nearly errorless set of relative concentrations that results in remarkably precise data; kinetic constant standard deviations are on the order of 0.5%.

Tang, Qingxiu; Leyh, Thomas S.

2010-01-01

392

High-rate artificial lift  

SciTech Connect

This paper summarizes the major considerations in the selection, design, installation, operation, or repair of high-rate artificial-lift systems. The major types of artificial lift - sucker-rod pumps, gas-lift systems, electrical submersible pumps, hydraulic pumps and jets, and hydraulic turbine-driven pumps - will be discussed. An extensive bibliography of artificial-lift papers is included.

Clegg, J.D.

1988-03-01

393

Diffusion rates for elevated releases  

SciTech Connect

A search of the literature related to diffusion from elevated sources has determined that an adequate data base exists for use in developing parameterizations for estimating diffusion rates for material released from free standing stacks at nuclear power plants. A review of published data analyses indicates that a new parameterization of horizontal diffusion rates specifically for elevated releases is not likely to significantly change the magnitudes of horizontal diffusion coefficients on the average. However, the uncertainties associated with horizontal diffusion coefficient estimates under any given set of atmospheric conditions could be reduced by a new parameterization. Similarly, a new parameterization of vertical diffusion rates would be unlikely to significantly alter the magnitudes of diffusion coefficients for unstable atmospheric conditons. However, for neutral and stable atmospheric conditions, a new parameterization of vertical diffusion rates might increase vertical diffusion coefficients significantly. The increase would move ground-level time-integrated concentration maxima closer to the plant and would increase the maxima. 55 references, 2 figures, 4 tables.

Ramsdell, J.V.

1983-11-01

394

Divergent Thinking and Interview Ratings  

ERIC Educational Resources Information Center

|This study examined divergent thinking (DT) test scores of applicants taking part in a selection procedure for an undergraduate psychology degree (N = 370). Interviewers made six specific (creative intelligence, motivation, work habits, emotional stability, sociability, and social responsibility) and one overall recommendation rating on each…

Batey, Mark; Rawles, Richard; Furnham, Adrian

2009-01-01

395

SIL Rating Fire Protection Equipment  

Microsoft Academic Search

SIL's (Safety Integrity Levels) are used by IEC 61508:1998 (1) to characterise the required functional safety of computer control systems. For example, SIL 4, the highest rating is for fly by wire aircraft and weapons systems and track circuited train signalling systems while SIL 2 is typical of certain Programmable Logic Controllers (PLC). Fire control panels have not been SIL

Richard M. Robinson; Kevin J. Anderson

2003-01-01

396

Avionics software problem occurrence rates  

Microsoft Academic Search

This paper discusses a feasibility study which developed estimates of the occurrence rate for significant avionics software problems. Two FAA databases, airworthiness directives (ADs) and service difficulty reports (SDRs) were used. A study of the AD database for large aircraft (1984-1994) revealed 33 avionics ADs, 13 of which were software related. Estimates were made of the operational hours for the

Martin L. Shooman

1996-01-01

397

EMISSION RATES FOR BIOGENIC NOX  

EPA Science Inventory

A literature review of biogenic sources of NOx was conducted to determine their emission rates into the atmosphere. NOx are some of the products of microbial denitrification, chemical decomposition of nitrites and the oxidation of organic nitrogen compounds. There appears to be n...

398

Exchange Rate Management in Ghana.  

National Technical Information Service (NTIS)

The history of exchange rate management in Ghana is one of the richest and most interesting in Africa. Before most African countries had established their own currencies, a balance of payments crisis in Ghana provoked an adverse terms of trade shock and e...

S. D. Younger

1993-01-01

399

Benchmarking the Effective Literacy Rate  

Microsoft Academic Search

By now the importance of literacy in the process of development is widely accepted. However, unlike measuring welfare or inequality, the problem of literacy measurement remains largely unexamined. Alternatives to the standard literacy rate, R, equal to the number of literate adults as a percentage of the adult population, are not well known, but this measure has its deficiencies. In

Travis Lee

2007-01-01

400

Benchmarking the effective literacy rate  

Microsoft Academic Search

Several authors have identified an externality accruing to proximate illiterates, that is, illiterate people with access to a literate person. The standard literacy rate ignores this externality; measures of effective literacy are sensitive to it. Nearly all measures of effective literacy appearing in the literature are greater than or equal to R. In fact, the best known of these, the

Travis Lee

2008-01-01

401

INTEREST RATE RISK QUANTIFICATION MODELS  

Microsoft Academic Search

The acceptance and management of financial risk is inherent to the business of banking and banks’ roles as financial intermediaries. To meet the demands of their customers and communities and to execute business strategies, banks make loans, purchase securities, and take deposits with different maturities and interest rates. These activities may leave a bank’s earnings and capital exposed to movements

Ana-Cornelia Puiu; Alina Nicoleta Radu

2008-01-01

402

Lung Cancer Rates by Race and Ethnicity  

MedlinePLUS

... and ethnicity. Incidence Rates by Race/Ethnicity and Sex "Incidence rate" means how many people out of ... Alaska Native). Death Rates by Race/Ethnicity and Sex From 1999–2009, the rate of people dying ...

403

Skin Cancer Rates by Race and Ethnicity  

MedlinePLUS

... and ethnicity. Incidence Rates by Race/Ethnicity and Sex "Incidence rate" means how many people out of ... Alaska Native). Death Rates by Race/Ethnicity and Sex From 1999–2009, the rate of people dying ...

404

Average heart rate, heart rate variability and the sympathovagal balance  

Microsoft Academic Search

Investigated are the responses of the average heart rate and of the balance between the 0.07-0.14 and 0.14-0.40-Hz components of the heart power spectrum to gravitational stress. This was done by taking finger blood pressure measurements in 18 young normals during two 1-hour sessions. In each session there were two supine-standing and two standing-supine transitions. For each transition the changes

Marc J. A. Janssen; Cees A. Swenne; Johan de Bie; Volkert Manger Cats; Albert V. G. Bruschke

1990-01-01

405

The mortality rate with ECT.  

PubMed

ECT is a low-risk procedure, even in the older cardiac patient who is fast becoming the modal candidate for this therapy. To put the mortal risk with ECT in proper perspective, it is only necessary to note that ECT is about 10 times safer than childbirth, that approximately 6 times as many deaths annually in the U.S. are caused by lightning as by ECT, that two complications of psychotropic drug therapy in younger women-fatal myocardial infarction and fatal subarachnoid hemorrhage-virtually never occur with ECT, and that the death rate reported for ECT is an order of magnitude smaller than the spontaneous death rate in the general population. PMID:9342128

Abrams, R

1997-09-01

406

Rating of tinted ophthalmic lenses  

NASA Astrophysics Data System (ADS)

This study aims at establishing the relationship between the spectral transmission characteristics of tinted ophthalmic lenses and the visual percept of the observer looking through. We hypothesize that the rating of tinted lenses originates from what the observer sees rather than what the glass looks like. We develop a model for color acceptance by calculating the color distortions for a collection of colored surfaces that are representative of the real environment using the spectral reflectance of the surfaces and the spectral transmittance of the lens. Then we apply the model to a collection of real tinted ophthalmic lenses and derive statistical indices that describes the global color distortion induced by each lens. Preliminary results show a significant agreement between the subjective rating and the objective color distortion index. We conclude that our model allows to predict the acceptance/rejection judgement of observers for a tinted ophthalmic lens of known spectral transmittance.

Vienot, Francoise; Benhalima, Fatima; Brettel, Hans; Bourdoncle, Bernard; Colonna de Lega, Alain

2002-06-01

407

Child Mortality Rate in Ethiopia  

PubMed Central

Ethiopia’s childhood mortality has continued to decline although at a swift pace. The drop in urban childhood mortality decline, duration of breastfeeding is the principle reason for the overall decline in mortality trends in Ethiopia. Data from the Ethiopian Demographic and Health Surveys 2000 and 2005 were used. Indirect estimation of Brass and Trussell’s methods were adopted. Selected demographic and socio-economic variables were included in the analysis with statistically significant effects. Findings clearly show neonatal and post neonatal mortality decline gradually. Even though, Ethiopia’s childhood mortality rates are still high. The result shows less than 2 years birth interval have higher infant mortality rates than higher birth interval (113 deaths per 1000). The proper spacing of births allows more time for childcare to make more maternal resources available for the care of the child and mother. Therefore, further research is urgent for regional level and national level investigation.

Susuman, A Sathiya

2012-01-01

408

Crystal Size and Cooling Rate  

NSDL National Science Digital Library

This activity relates to the process of igneous rock formation by the cooling of magma. It can be used to illustrate how the rate at which molten rock cools affects the size of the crystals that form within the solid rock - rapid cooling producing small crystals, slower cooling producing larger ones. Hot, saturated solutions of lead iodide are cooled at different rates. The solution that cools faster produces smaller crystals. Students relate this to samples of rhyolite and granite and discover that the intrusive igneous rock (the granite) has cooled slowly from magma, and the rhyolite lava (extrusive igneous rock) has cooled very quickly. This leads to a fuller explanation of the terms intrusive and extrusive. The site also has an alternative demonstration in which melted Salol is placed on hot and cold glass slides with similar results.

409

Evaporation rate of nucleating clusters  

Microsoft Academic Search

The Becker-Do¨ring kinetic scheme is the most frequently used approach to vapor liquid nucleation. In the present study it has been extended so that master equations for all cluster configurations are included into consideration. In the Becker-Do¨ring kinetic scheme the nucleation rate is calculated through comparison of the balanced steady state and unbalanced steady state solutions of the set of

Evgeni Zapadinsky

2011-01-01

410

Solar PV- Standby Rate Estimator  

NSDL National Science Digital Library

The Advanced Technology Environmental and Energy Center (ATEEC) provides this spreadsheet to be used in conjunction with the Standby Rate Manual (available for download here). The document aims to help businesses analyze the potential energy savings of implementing an on site combined heat and power (CHP) system. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

2011-03-01

411

Maintenance Strategy Maximising Availability Rate  

NASA Astrophysics Data System (ADS)

Electronic equipment operates under various conditions. Due to characteristic nature of its applications (e.g. in transport), it should be highly reliable. Many years’ worth of observations show, those systems not only require their constituting parts to function up to par, but also their maintenance has to be efficiently managed. This paper presents maintenance strategies and particularly focuses on maintenance strategy enabling maximising the availability rate.

Rosi?ski, Adam

2012-12-01

412

Instructor Reputation and Teacher Ratings  

NSDL National Science Digital Library

Created by David M. Lane of Rice University, this case study covers concepts including: boxplots, stem and leaf displays, two-sample t tests, and analysis of variance. It also assesses the question, "Does an instructor's reputation affect ratings of the instructor's lecture?" The author divides the lesson in these way: background, experimental design, descriptive statistics, inferential statistics, instructions for SPSS and the raw data set. This is a carefully designed case study which employs many methods important to statistical research.

Lane, David M.

2009-02-25

413

[High dose rate prostate brachytherapy].  

PubMed

This article aims at presenting the interest of high dose rate brachytherapy in the radiation treatment of prostatic adenocarcinoma. We will discuss successively the biological and dosimetric specificity of brachytherapy for this particular cancer. Afterwards, we will review the main phase II and III studies, the therapeutic indications in the daily practice from the evidence based medicine as well as the techniques of external beam radiation therapy for the same indications. Finally, the principal avenues of development will be discussed. PMID:23578898

Nickers, P; Blanchard, P; Hannoun-Lévi, J-M; Bossi, A; Chapet, O; Guérif, S

2013-04-08

414

Pricing growth-rate risk  

Microsoft Academic Search

We characterize the compensation demanded by investors in equilibrium for incremental exposure to growth-rate risk. Given\\u000a an underlying Markov diffusion that governs the state variables in the economy, the economic model implies a stochastic discount\\u000a factor process S. We also consider a reference growth process G that may represent the growth in the payoff of a single asset or of

Lars Peter Hansen; José A. Scheinkman

2012-01-01

415

Learning rates for energy technologies  

Microsoft Academic Search

Technological learning, i.e., cost reductions as technology manufacturers accumulate experience, is increasingly being incorporated in models to assess long-term energy strategies and related greenhouse gas emissions. Most of these applications use learning rates based on studies of non-energy technologies, or sparse results from a few energy studies. This report is a step towards a larger empirical basis for choosing learning

Alan McDonald; Leo Schrattenholzer

2001-01-01

416

Tree Migration-Rates: Narrowing the Gap between Inferred Post-Glacial Rates and Projected Rates  

PubMed Central

Faster-than-expected post-glacial migration rates of trees have puzzled ecologists for a long time. In Europe, post-glacial migration is assumed to have started from the three southern European peninsulas (southern refugia), where large areas remained free of permafrost and ice at the peak of the last glaciation. However, increasing palaeobotanical evidence for the presence of isolated tree populations in more northerly microrefugia has started to change this perception. Here we use the Northern Eurasian Plant Macrofossil Database and palaeoecological literature to show that post-glacial migration rates for trees may have been substantially lower (60–260 m yr–1) than those estimated by assuming migration from southern refugia only (115–550 m yr–1), and that early-successional trees migrated faster than mid- and late-successional trees. Post-glacial migration rates are in good agreement with those recently projected for the future with a population dynamical forest succession and dispersal model, mainly for early-successional trees and under optimal conditions. Although migration estimates presented here may be conservative because of our assumption of uniform dispersal, tree migration-rates clearly need reconsideration. We suggest that small outlier populations may be a key factor in understanding past migration rates and in predicting potential future range-shifts. The importance of outlier populations in the past may have an analogy in the future, as many tree species have been planted beyond their natural ranges, with a more beneficial microclimate than their regional surroundings. Therefore, climate-change-induced range-shifts in the future might well be influenced by such microrefugia.

Feurdean, Angelica; Bhagwat, Shonil A.; Willis, Katherine J.; Birks, H. John B; Lischke, Heike; Hickler, Thomas

2013-01-01

417

Leakage Rates for Cryolab Valves  

SciTech Connect

This note summarizes a brief study on the leakage rates of cryolab valves due to the failure of the valve packings. The {Delta}r gap between the shaft and the packing, the fluid (Ar or N2), the {Delta}p (atm) between the fluid and atmosphere, and the initial temperature of the escaping gas were varied to determine the resulting leakage rate. The heat leak in watts required to vaporize the liquid which provides the indicated flow rates is also included in the results. The dimensions used in the calculations were acquired over the telephone and/or found on the enclosed drawing from Cryolab. There is no implication that Cryolab was any better or worse than other valve manufacturers. They were kind enough to provide the detail needed for this study. The fluid properties were found in Ar and N2 Property handbooks. The results of this study are shown graphically and listed on accompanying spread sheets. The spread sheets and graphs can be found on the disc JW4 in the MassFlow folder.

Wendlandt, J.M.; /Fermilab

1988-11-02

418

The Rate of Compensatory Evolution  

PubMed Central

A two-locus model is presented to analyze the evolution of compensatory mutations occurring in stems of RNA secondary structures. Single mutations are assumed to be deleterious but harmless (neutral) in appropriate combinations. In proceeding under mutation pressure, natural selection and genetic drift from one fitness peak to another one, a population must therefore pass through a valley of intermediate deleterious states of individual fitness. The expected time for this transition is calculated using diffusion theory. The rate of compensatory evolution, k(c), is then defined as the inverse of the expected transition time. When selection against deleterious single mutations is strong, k(c) depends on the recombination fraction r between the two loci. Recombination generally reduces the rate of compensatory evolution because it breaks up favorable combinations of double mutants. For complete linkage, k(c) is given by the rate at which favorable combinations of double mutants are produced by compensatory mutation. For r>0, k(c) decreases exponentially with r. In contrast, k(c) becomes independent of r for weak selection. We discuss the dynamics of evolutionary substitutions of compensatory mutants in relation to WRIGHT's shifting balance theory of evolution and use our results to analyze the substitution process in helices of mRNA secondary structures.

Stephan, W.

1996-01-01

419

3D fold growth rates  

NASA Astrophysics Data System (ADS)

Geological folds are inherently three-dimensional structures. Therefore, a growing fold structure also propagates in three dimensions. In this study, fold growth in all three dimensions is studied and quantified numerically using a finite-element algorithm for simulating three-dimensional deformation of Newtonian materials. To simplify terminology, only upright symmetrical single-layer fold structures are considered here. The horizontal higher-viscous layer exhibits an initial point perturbation. Horizontal compression in one direction (x-direction) leads to a mechanical folding instability, which grows from this perturbation in all three dimensions, described by: Fold amplification (growth in z-direction) The fold growth in z-direction (vertical) is commonly referred to as fold amplification and describes the growth from a fold shape with low limb-dip angle to a shape with higher limb-dip angle. Fold elongation (growth in y-direction) The fold growth in y-direction is parallel to the fold axis and is here referred to as fold elongation. It describes the growth from a dome-shaped (3D) structure to a more cylindrical fold (2D). Sequential fold growth (growth in x-direction) The fold growth in x-direction is parallel to the shortening direction and perpendicular to the fold axis. It describes the growth of secondary (and further) folds adjacent to the initial isolated fold and is here referred to as sequential fold growth. In existing literature, both fold elongation and sequential fold growth have previously been referred to as lateral fold growth, which is here used as an umbrella term for both. First results indicate that in the initial folding stage, the fold growth rates in all three dimensions are of the same order. However, after some shortening and fold amplification, the two lateral growth rates first increase significantly and then decrease below the value of the vertical fold amplification. At a later folding stage, the vertical amplification rate of the initial fold also decreases and the sequentially grown secondary folds exhibit higher vertical amplification rates. During the entire modeled folding history, the two lateral directions generally show a very similar growth rate.

Frehner, Marcel

2013-04-01

420

The relationship among flow rate, chamber volume and calculated rate of metabolism in vertebrate respirometry  

Microsoft Academic Search

A relationship exists among the calculated rate of metabolism of an animal enclosed in a chamber, chamber volume and air flow rate. A “critical” flow rate, defined as the minimal flow rate that produces a complete mixture of chamber gases, characterizes each chamber\\/animal combination. At flow rates below the critical flow rate, calculated rates of metabolism decrease with flow rate

Brian K. McNab

2006-01-01

421

39 CFR 3010.25 - Limitation on unused rate adjustment authority rate adjustments.  

Code of Federal Regulations, 2013 CFR

... POSTAL REGULATORY COMMISSION PERSONNEL REGULATION OF RATES FOR MARKET DOMINANT PRODUCTS Rules for Applying the Price Cap § 3010.25 Limitation on unused rate adjustment authority rate adjustments. Unused rate adjustment authority rate...

2013-07-01

422

Charge balancing fill rate monitor  

SciTech Connect

A fill rate monitor has been developed for the NSLS storage rings to allow machine tuning over a very large dynamic range of beam current. Synchrotron light, focused on a photodiode, produces a signal proportional to the beam current. A charge balancing circuit processes the diode current, creating an output signal proportional to the current injected into the ring. The unit operates linearly over a dynamic range of 120 dB and can resolve pulses of injected beam as small as 1 {mu}A.

Rothman, J.L.; Blum, E.B.

1995-12-31

423

Reaction rates in hydrophilic glass  

NASA Astrophysics Data System (ADS)

Sugar-based glasses are known to stabilize proteins against aggregation and chemical degradation. It has long been supposed that, due to the long timescales involved in protein aggregation and chemical degradation in the glass, relaxation processes essentially control the rate of degradation. We have shown that, although the degradation processes occur on timescales of the alpha relaxation process, secondary relaxation processes, and not alpha relaxation seems to dominate in influencing both chemical and physical degradation. In this presentation we will discuss results from time-resolved fluorescence studies in sugar-based glasses designed to help understand the physics underlying these puzzling observations.

Cicerone, Marcus; Zhong, Qin

2010-03-01

424

Universality in movie rating distributions  

Microsoft Academic Search

In this paper histograms of user ratings for movies\\u000a (1,...,10) are analysed. The evolving stabilised shapes of\\u000a histograms follow the rule that all are either double- or triple-peaked.\\u000a Moreover, at most one peak can\\u000a be on the central bins 2,...,9 and the distribution in these\\u000a bins looks smooth `Gaussian-like’ while changes at the extremes (1 and \\u000a 10) often look\\u000a abrupt.

Jan Lorenz

2009-01-01

425

Sovereign credit ratings: Guilty beyond reasonable doubt?  

Microsoft Academic Search

This paper questions the view that credit rating agencies aggravated the East Asian crisis by excessively downgrading those countries. I find that ratings are, if anything, sticky rather than procyclical. Assigned ratings exceeded predicted ratings before the crisis, mostly matched predicted ratings during the crisis period, and did not increase as much as predictions in the period after the crisis.

Nada Mora

2006-01-01

426

Further Study on Atmospheric Lapse Rate Regimes  

Microsoft Academic Search

Lapse rate, moist adiabatic lapse rate and the critical lapse rate for baroclinic adjustment are calculated as was done by Stone and Carlson using a different data set covering both hemispheres. Results show very good agreement in low latitudes, where temperature lapse rate can be approximated by the moist adiabatic lapse rate. In midlatitudes of the Northern Hemisphere, the lapse

Shi-Keng Yang; G. Louis Smith

1985-01-01

427

Atmospheric Lapse Rate Regimes and Their Parameterization  

Microsoft Academic Search

Lapse rates, moist adiabatic lapse rates and the critical lapse rate for baroclinic adjustment are calculated and compared for the mean annual, January and July states in the Northern Hemisphere. In the troposphere above the planetary boundary layer zonal mean lapse rates are within 20% of the moist adiabatic lapse rate from the equator up to about 30°N in January

Peter H. Stone; John H. Carlson

1979-01-01

428

A New Rate Law Describing Microbial Respiration  

Microsoft Academic Search

The rate of microbial respiration can be described by a rate law that gives the respiration rate as the product of a rate constant, biomass concentration, and three terms: one describing the kinetics of the electron-donating reaction, one for the kinetics of the electron-accepting reaction, and a thermodynamic term accounting for the energy available in the microbe's environment. The rate

Qusheng Jin; Craig M. Bethke

2003-01-01

429

Ratings in Distributed Systems: A Bayesian Approach  

Microsoft Academic Search

For distributed systems at large and e-commerce systems in particular, ratings play an increasingly important role. Ratings confer reputation measures about sources. This paper reports our formalization of the rating process. This paper argues that ratings should be context- and individual- dependent quantities. In contrast to existing rating systems in many e-commerce or developer sites, our approach makes use of

Lik Mui; Mojdeh Mohtashemi; Cheewee Ang; Peter Szolovits; Ari Halberstadt

2001-01-01

430

Reconnection rates of magnetic fields  

SciTech Connect

The Sweet-Parker and Petschek scalings of magnetic reconnection rate are modified to include the effect of the viscosity. The modified scalings show that the viscous effect can be important in high-..beta.. plasmas. The theoretical reconnection scalings are compared with numerical simulation results in a tokamak geometry for three different cases: a forced reconnection driven by external coils, the nonlinear m = 1 resistive internal kink, and the nonlinear m = 2 tearing mode. In the first two cases, the numerical reconnection rate agrees well with the modified Sweet-Parker scaling, when the viscosity is sufficiently large. When the viscosity is negligible, a steady state which was assumed in the derivation of the reconnection scalings is not reached and the current sheet in the reconnection layer either remains stable through sloshing motions of the plasma or breaks up to higher m modes. When the current sheet remains stable, a rough comparison with the Sweet-Parker scaling is obtained. In the nonlinear m = 2 tearing mode case where the instability is purely resistive, the reconnection occurs on the slower dissipation time scale (Psi/sub s/ approx. eta). In addition, experimental data of the nonlinear m = 1 resistive internal kink in tokamak discharges are analyzed and are found to give reasonable agreement with the modified Sweet-Parker scaling.

Park, W.; Monticello, D.A.; White, R.B.

1983-05-01

431

Pathfinding of corticothalamic axons relies on a rendezvous with thalamic projections  

PubMed Central

Summary Major outputs of the neocortex are conveyed by corticothalamic axons (CTA), which form reciprocal connections with thalamocortical axons, and corticosubcerebral axons (CSA) headed to more caudal parts of the nervous system. Previous findings establish that transcriptional programs define cortical neurons identity and suggest that CTA and thalamic axons may guide each other, but the mechanisms governing CTA versus CSA pathfinding remain elusive. Here, we show that thalamocortical axons are required to guide pioneer CTA away from a default CSA-like trajectory. This process relies on a hold in the progression of cortical axons, or waiting period, during which thalamic projections navigate towards cortical axons. At the molecular level, Sema3E/PlexinD1 signaling in pioneer cortical neurons mediates a “waiting signal” required to orchestrate the mandatory meeting with reciprocal thalamic axons. Our study reveals that temporal control of axonal progression contributes to spatial pathfinding of cortical projections and opens novel perspectives on brain wiring.

Deck, M.; Lokmane, L.; Chauvet, S.; Mailhes, C.; Keita, M.; Niquille, M.; Yoshida, M.; Yoshida, Y.; Lebrand, C.; Mann, F.; Grove, E.A.; Garel, S.

2013-01-01

432

Low-thrust Optimal Trajectories for Rendezvous with Near Earth Asteroids  

NASA Astrophysics Data System (ADS)

The interest of the scientific community for small bodies has been growing for the last decades. A direct consequence is the number of missions or projects envisaged by national space agencies considering asteroids and comets as potential targets. We can quote for example NEAR to asteroid Eros and ROSETTA to comet 67P/Churyumov-Gerasimenko. A crucial point for the mission design is the cost, in terms of propellant requirement. Some interesting bodies, indeed, may not be reached by means of classical chemical propulsion because of the propellant mass having to be loaded on board. In this framework, the use of electric propulsion allows to consider either targets needing a lot of energy to be reached or multiple targets in a one way mission. Moreover, the computation of low-thrust optimal trajectories is a very complex task. The solution of the associated optimal control problems is done by combined means of the maximum principle, non-classical smoothing techniques and decomposition-coordination methods. After the general formulation and definition of the problems, we will present different optimal trajectories to various targets (such as Orpheus, Anteros, 1999FG3…) including the Earth escape phase and the heliocentric cruise. Complex options with flyby of intermediate asteroids or with gravity assist of the Earth are also proposed.

Bertrand, R.; Foliard, J.

433

Small body rendezvous mission using solar electric ion propulsion: Low cost mission approach and technology requirements  

Microsoft Academic Search

This paper shows that existing solar electric ion propulsion (SEP) technology can deliver substantial payloads to important small bodies for an effective cost. SEP, using hardware being validated by the NASA SEP Technology Application Readiness (NSTAR) program, can deliver significantly more mass in a dramatically shorter period of time than a chemical propulsion system launched from the same Delta II

Roy Kakuda; Joel Sercel; Wayne Lee

1995-01-01

434

Autonomous Reconfigurable GPS/INS Navigation and Pointing System for Rendezvous and Docking.  

National Technical Information Service (NTIS)

This paper describes the results of an integrated navigation and pointing system software development effort sponsored by the NASA MSFC through a SBIR Phase 2 Program. The integrated Global Positioning System (GPS)/Inertial Navigation System (INS) impleme...

T. N. Upadhyay S. Cotterill A. W. Deaton

1991-01-01

435

Autonomous reconfigurable GPS/INS navigation and pointing system for rendezvous and docking  

NASA Astrophysics Data System (ADS)

This paper describes the results of an integrated navigation and pointing system software development effort sponsored by the NASA MSFC through a SBIR Phase 2 Program. The integrated Global Positioning System (GPS)/Inertial Navigation System (INS) implements an autonomous navigation filter that is reconfigurable in real-time to accommodate mission contingencies. An onboard expert system monitors the spacecraft status and reconfigures the navigation filter accordingly, to optimize the system performance. The navigation filter is a multi-mode Kalman filter to estimate the spacecraft position, velocity, and attitude. Three different GPS-based attitude determination techniques, namely, velocity vector matching, attitude vector matching, and interferometric processing, are implemented to encompass different mission contingencies. The integrated GPS/INS navigation filter will use any of these techniques depending on the mission phase and the state of the sensors. The first technique, velocity vector matching, uses the GPS velocity measurement to estimate the INS velocity errors and exploits the correlation between INS velocity and attitude errors to estimate the attitude. The second technique, attitude vector matching, uses INS gyro measurements and GPS carrier phase (integrated Doppler) measurements during a spacecraft rotation maneuver to determine the attitude. Both of these techniques require only one GPS antenna onboard to determine the spacecraft attitude. The third technique, interferometric processing, requires use of multiple GPS antennae. In order to determine 3-axis body attitude, three GPS antennae (2 no-coplanor baselines) are required.

Upadhyay, Triveni N.; Cotterill, Stephen; Deaton, A. Wayne

436

Pathfinding of corticothalamic axons relies on a rendezvous with thalamic projections.  

PubMed

Major outputs of the neocortex are conveyed by corticothalamic axons (CTAs), which form reciprocal connections with thalamocortical axons, and corticosubcerebral axons (CSAs) headed to more caudal parts of the nervous system. Previous findings establish that transcriptional programs define cortical neuron identity and suggest that CTAs and thalamic axons may guide each other, but the mechanisms governing CTA versus CSA pathfinding remain elusive. Here, we show that thalamocortical axons are required to guide pioneer CTAs away from a default CSA-like trajectory. This process relies on a hold in the progression of cortical axons, or waiting period, during which thalamic projections navigate toward cortical axons. At the molecular level, Sema3E/PlexinD1 signaling in pioneer cortical neurons mediates a "waiting signal" required to orchestrate the mandatory meeting with reciprocal thalamic axons. Our study reveals that temporal control of axonal progression contributes to spatial pathfinding of cortical projections and opens perspectives on brain wiring. PMID:23395374

Deck, Marie; Lokmane, Ludmilla; Chauvet, Sophie; Mailhes, Caroline; Keita, Maryama; Niquille, Mathieu; Yoshida, Michio; Yoshida, Yutaka; Lebrand, Cécile; Mann, Fanny; Grove, Elizabeth A; Garel, Sonia

2013-02-01

437

Dawn of the Space Age and Preparation for APOLLO-Soyuz Rendezvous.  

National Technical Information Service (NTIS)

The technological achievements of the space age are touched upon in terms of the Apollo-Soyuz Test Project. It is indicated that the most important aspect of Apollo-Soyuz is international cooperation in the field of space.

G. E. Low

1975-01-01

438

Low-Thrust Mission Risk Analysis, with Application to a 1980 Rendezvous with the Comet Encke.  

National Technical Information Service (NTIS)

A computerized failure process simulation procedure is used to evaluate the risk in a solar electric space mission. The procedure uses currently available thrust-subsystem reliability data and performs approximate simulations of the thrust sybsystem burn ...

C. L. Yen D. B. Smith

1973-01-01

439

Exploration of a Two Sided Rendezvous Search Problem Using Genetic Algorithms  

Microsoft Academic Search

The problem of searching for a walker that wants to be found, when the walker moves toward the helicopter when it can hear\\u000a it, is an example of a two sided search problem which is intrinsically difficult to solve. Thomas et al [1] considered the effectiveness of three standard NATO search paths [2] for this type of problem. In this

T. Q. S. Truong; A. Stacey

2003-01-01

440

Basic targeting strategies for rendezvous and flyby missions to the near-Earth asteroids  

Microsoft Academic Search

Missions to asteroids and comets are becoming increasingly feasible both from a technical and a financial point of view. In particular, those directed towards the Near-Earth Asteroids have proven suitable for a low-cost approach, thus attracting the major space agencies as well as private companies. The choice of a suitable target involves both scientific relevance and mission design considerations, being

Ettore Perozzi; Alessandro Rossi; Giovanni B. Valsecchi

2001-01-01

441

Target selection and accessibility for rendezvous with a Near-Earth asteroid mission  

Microsoft Academic Search

Mission to asteroids and comets has been the hot spot of deep space exploration in the new century. The choice of a suitable\\u000a target, which involves both scientific value and technical feasibility, becomes a difficult task to accomplish due to limited\\u000a energy and technology. The aim of this paper is to provide an approach to selecting a target and evaluating

Dong Qiao; Pingyuan Cui; Hutao Cui

2007-01-01

442

7 CFR 1777.31 - Rates.  

Code of Federal Regulations, 2013 CFR

...a) Applicant loans will bear interest at the rate of 5 percent per annum. (b) Individual loans will bear interest at the rate of: (1) Five percent per... (2) The Federal Financing Bank rate for loans of a similar...

2013-01-01

443

76 FR 53160 - Postal Service Rate Adjustment  

Federal Register 2010, 2011, 2012, 2013

...generally in more remunerative rates than the default rates set by the UPU Acts for inbound...to provide information on mail flows within the annual compliance review...common description, and applies to rates for letter-class items...

2011-08-25

444

78 FR 62616 - Integrated System Power Rates  

Federal Register 2010, 2011, 2012, 2013

...pursuant to the provisions of this Rate Schedule based on metered flow through the interconnection...5. Transformation Service Rates, Terms, and Conditions 2...its load, such that energy flows at rates beyond the authorized...

2013-10-22

445

75 FR 1363 - Integrated System Power Rates  

Federal Register 2010, 2011, 2012, 2013

...its load, such that energy flows at rates beyond the authorized bandwidth...pursuant to the provisions of this Rate Schedule based on metered flow through the interconnection...Facilities Services is assessed. Rate for Interconnection...

2010-01-11

446

77 FR 67644 - Examination Rating System  

Federal Register 2010, 2011, 2012, 2013

...Operational risk, and will be referred to as the Entity's ``CAMELSO'' rating. That rating system is similar to the ``CAMELS'' rating system used by the federal banking regulators for depository institutions. For the Banks' joint office, the...

2012-11-13

447

77 FR 36536 - Examination Rating System  

Federal Register 2010, 2011, 2012, 2013

...and would be referred to as the regulated entity's ``CAMELSO'' rating. That rating system would be similar to the ``CAMELS'' rating system used by the federal banking regulators for depository institutions. For the Banks' joint office,...

2012-06-19

448

12 CFR 327.4 - Assessment rates.  

Code of Federal Regulations, 2013 CFR

...institution cannot request review through this process of the CAMELS ratings assigned by its primary federal regulator or...or state authority of its supervisory rating (even when the CAMELS component ratings have not been disclosed to the...

2013-01-01

449

24 CFR 597.103 - Poverty rate.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 false Poverty rate. 597.103 Section 597.103 Housing...DESIGNATIONS Area Requirements § 597.103 Poverty rate. (a) General. The poverty rate shall be established in accordance...

2013-04-01

450

77 FR 65664 - Publication of Depreciation Rates  

Federal Register 2010, 2011, 2012, 2013

...Rural Utilities Service Publication of Depreciation Rates AGENCY: Rural Utilities Service...Telecommunications Program. RUS announces the depreciation rates for telecommunications plant...Sec. 1737.70(e) explains the depreciation rates that are used by RUS in its...

2012-10-30

451

76 FR 6762 - Publication of Depreciation Rates  

Federal Register 2010, 2011, 2012, 2013

...Rural Utilities Service Publication of Depreciation Rates AGENCY: Rural Utilities Service...Agriculture (USDA), announces the depreciation rates for telecommunications plant...Sec. 1737.70(e) explains the depreciation rates that are used by RUS in its...

2011-02-08

452

76 FR 72672 - Publication of Depreciation Rates  

Federal Register 2010, 2011, 2012, 2013

...Rural Utilities Service Publication of Depreciation Rates AGENCY: Rural Utilities Service...Telecommunications Program. RUS announces the depreciation rates for telecommunications plant...Sec. 1737.70(e) explains the depreciation rates that are used by RUS in its...

2011-11-25

453

Reedbed evapotranspiration rates in England  

NASA Astrophysics Data System (ADS)

Measurements of evapotranspiration from contrasting stands of Phragmites australis [ET(Reed)] were obtained over several years at three sites within England between 1994 and 1998. A comparison with published ET(Reed) values showed the UK rates to be considerably lower than those measured in continental Europe. From the ET(Reed) data monthly crop coefficients [Kc(Reed)] have been developed, which when used with Reference Crop Evapotranspiration will enable reedbed water use to be determined. Due to the differences in study site characteristics, values for Kc varied widely, and it was not considered appropriate to combine results to produce a single set of monthly mean values. However, suggestions are made regarding the application of the Kc(Reed) values to wetland design.

Fermor, P. M.; Hedges, P. D.; Gilbert, J. C.; Gowing, D. J. G.

2001-03-01

454

Theoretical model of relationship between frame-rate and bit-rate for encoding high frame-rate video signal  

Microsoft Academic Search

Higher frame-rates are being considered to achieve more realistic representations. Since increasing the frame-rate increases the total amount of information, efficient coding methods are required. However, its statistical properties are not clarified. This paper establishes for high frame-rate video a mathematical model of the relationship between frame-rate and bit-rate. A coding experiment confirms the validity of the mathematical model.

Yukihiro Bandoh; Seishi Takamura; Kazuto Kamikura; Yoshiyuki Yashima

2005-01-01

455

Failure rate analysis using GLIMMIX  

SciTech Connect

This paper illustrates use of a recently developed SAS macro, GLIMMIX, for implementing an analysis suggested by Wolfinger and O`Connell (1993) in modeling failure count data with random as well as fixed factor effects. Interest in this software tool arose from consideration of modernizing the Failure Rate Analysis Code (FRAC), developed at Los Alamos National Laboratory in the early 1980`s by Martz, Beckman and McInteer (1982). FRAC is a FORTRAN program developed to analyze Poisson distributed failure count data as a log-linear model, possibly with random as well as fixed effects. These statistical modeling assumptions are a special case of generalized linear mixed models, identified as GLMM in the current statistics literature. In the nearly 15 years since FRAC was developed, there have been considerable advances in computing capability, statistical methodology and available statistical software tools allowing worthwhile consideration of the tasks of modernizing FRAC. In this paper, the approaches to GLMM estimation implemented in GLIMMIX and in FRAC are described and a comparison of results for the two approaches is made with data on catastrophic time-dependent pump failures from a report by Martz and Whiteman (1984). Additionally, statistical and graphical model diagnostics are suggested and illustrated with the GLIMMIX analysis results.

Moore, L.M.; Hemphill, G.M.; Martz, H.F.

1998-12-01

456

Rate of runaway evaporative cooling  

SciTech Connect

Evaporative cooling is a process that is essential in creating Bose-Einstein condensates in dilute atomic gasses. This process has often been simulated based on a model using a truncated Boltzmann distribution. This model assumes that the energy distribution up to the threshold energy can still be described by a Boltzmann distribution: it assumes detailed balance up to the threshold energy. However, the evolution of the distribution function in time is not taken into account. Here we solve the kinetic Boltzmann equation for a gas undergoing evaporative cooling in a harmonic and linear trap in order to determine the evolution of the energy distribution. The magnitude of the discrepancy with the truncated Boltzmannmodel is calculated by including a polynomial expansion of the distribution function. We find that up to 35% fewer particles are found in the high-energy tail of the distribution with respect to the truncated Boltzmann distribution and up to 15% more collisions are needed to reach quantum degeneracy. Supported by a detailed investigation of the particle loss rate at different energies, we conclude that the limited occupation of high-energy states during the evaporation process causes the lowering of the evaporation speed and efficiency.

Groep, J. van de; Straten, P. van der; Vogels, J. M. [Atom Optics and Ultrafast Dynamics, Utrecht University, P.O. Box 80, 000, NL-3508 TA Utrecht (Netherlands)

2011-09-15

457

Image migration: measured retrieval rates  

NASA Astrophysics Data System (ADS)

When the Indianapolis Veterans Affairs Medical Center changed Picture Archiving and Communication Systems (PACS) vendors, we chose to use "on demand" image migration as the more cost effective solution. The legacy PACS stores the image data on optical disks in multi-platter jukeboxes. The estimated size of the legacy image data is about 5 terabytes containing studies from ~1997 to ~2003. Both the legacy and the new PACS support a manual DICOM query/retrieve. We implemented workflow rules to determine when to fetch the relevant priors from the legacy PACS. When a patient presents for a new radiology study, we used the following rules to initiate the manual DICOM query/retrieve. For general radiography we retrieved the two most recent prior examinations and for the modalities MR and CT we retrieved the clinically relevant prior examinations. We monitored the number of studies retrieved each week for about a 12 month period. For our facility which performs about 70,000 radiology examinations per year, we observed an essentially constant retrieval rate of slightly less than 50 studies per week. Some explanations for what may be considered an anomalous result maybe related to the fact that we are a tertiary care facility and a teaching hospital.

Witt, Robert M.

2007-03-01

458

Flow rate logging seepage meter  

NASA Astrophysics Data System (ADS)

An apparatus for remotely measuring and logging the flow rate of groundwater seepage into surface water bodies is described. As groundwater seeps into a cavity created by a bottomless housing, it displaces water through an inlet and into a waterproof sealed upper compartment, at which point, the water is collected by a collection bag, which is contained in a bag chamber. A magnet on the collection bag approaches a proximity switch as the collection bag fills, and eventually enables the proximity switch to activate a control circuit. The control circuit then rotates a three-way valve from the collection path to a discharge path, enables a data logger to record the time, and enables a pump, which discharges the water from the collection bag, through the three-way valve and pump, and into the sea. As the collection bag empties, the magnet leaves the proximity of the proximity switch, and the control circuit turns off the pump, resets the valve to provide a collection path, and restarts the collection cycle.

Reay, William G.; Walthall, Harry G.

1992-12-01

459

Rising interest rates, bank loans, and deposits  

Microsoft Academic Search

The authors show how the relationships between interest rate changes, deposit growth rates, and loan growth rates have changed in the last ten years, discuss some possible reasons, and assess the likely impact of rising interest rates on loans and deposits going forward.

Hesna Genay; Darrin R. Halcomb

2004-01-01

460

Retention Rate by Ethnicity. Information Capsule.  

ERIC Educational Resources Information Center

|This document discusses retention rate based on ethnicity for Miami-Dade Community College (M-DCC) for December 2002. The study found that the 2001 Fall-Spring retention rates increased among all ethnic groups. The total college retention rate rose by 2.7 percentage points to 75.2%. Among individual groups, the highest retention rate of 76.9% was…

Baldwin, Anne

461

76 FR 7883 - Postal Service Rate Adjustment  

Federal Register 2010, 2011, 2012, 2013

...remunerative rates than the default rates set by the Universal Postal...inadvertently that the agreement's rates are intended to become effective...provide information on mail flows within the annual compliance...description, and relates to rates for Letter Post tendered...

2011-02-11

462

A STROBOSCOPIC DEVICE FOR MEASURING REVOLUTION RATES  

Microsoft Academic Search

An inexpensive device for measuring rotation rates can be made by mounting two paper discs on rotating axes. If the rate of one is known, the rate of the other can be determined by finding the ratio between the two speeds stroboscopically. One disc may be put in place of a record in a good phonograph. The rate of revolution

Benjamin Franklin Zuehl

1922-01-01

463

24 CFR 206.21 - Interest rate.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 2009-04-01 false Interest rate. 206.21 Section 206.21 Housing and...Endorsement Eligible Mortgages § 206.21 Interest rate. (a) Fixed interest rate. A fixed interest rate is agreed upon...

2009-04-01

464

24 CFR 206.21 - Interest rate.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Interest rate. 206.21 Section 206.21 Housing and...Endorsement Eligible Mortgages § 206.21 Interest rate. (a) Fixed interest rate. A fixed interest rate is agreed upon...

2010-04-01

465

Comparison of Thought-Listing Rating Methods.  

ERIC Educational Resources Information Center

Compared three methods of rating thoughts: self-rating by subjects, rating by experts with thoughts presented randomly, and rating by experts with thoughts presented in context among 107 students who listed their thoughts prior to giving a speech. Results indicated all three methods were equal in predictions of speech anxiety and performance.…

Tarico, Valerie S.; And Others

1986-01-01

466

LIFE INSURANCE WITH STOCHASTIC INTEREST RATE  

Microsoft Academic Search

Pricing of insurance product is usually evaluated on a basis where interest rate is assumed to be fixed over time. To obtain a more realistic assessment of the pricing of its product it would be benefit if the interest rates are fluctuating. This paper compares actuarial quantities which calculated based on fixed interest rate to stochastic interest rate using the

L. Noviyanti; M. Syamsuddin

467

ESTIMATING TRUCK RATES FOR REFRIGERATED FOOD PRODUCTS  

Microsoft Academic Search

Food companies and analysts often need transportation rate data to explore market opportunities. In some cases, it may not be practical or necessary to obtain actual rates for all routes under consideration. This study provides analysis of truck rate patterns and alternative rate-estimating equations. The original objective was to provide shipping cost estimates for a national beef-marketing model involving 30

J. B. Ward; Donald E. Farris

1990-01-01

468

Empirical Properties of Foreign Exchange Rates  

Microsoft Academic Search

This paper investigates the behavior of foreign exchange rates. Empirical tests indicate that the distribution of the underlying stochastic process for foreign exchange rate changes was stable paretion during fixed rate periods while a Student model provides a relatively better description of floating rates. These findings point to an important direction for further work on the appropriate distribution for foreign

Richard J. Rogalski; Joseph D. Vinso

1978-01-01

469

Empirical Properties of Foreign Exchange Rates  

Microsoft Academic Search

This paper investigates the behavior of foreign exchange rates. Empirical tests indicate that the distribution of the underlying stochastic process for foreign exchange rate changes was stable paretion during fixed rate periods while a Student model provides a relatively better description of floating rates. These findings point to an important direction for further work on the appropriate distribution for foreign

Richard J. Rogalski; Joseph D. Vinso

470

Extendsim Advanced Techology: Discrete Rate Simulation  

Microsoft Academic Search

ExtendSim is used to model continuous, discrete event, discrete rate, and agent-based systems. This paper will focus on the ExtendSim discrete rate capabilities for modeling high-speed and rate based systems. Continuous, discrete event, and discrete rate simulation models will be compared.

David Krahl

2009-01-01

471

Rate Splitting MIMO-based MAC Protocol  

Microsoft Academic Search

Multiple input multiple output (MIMO) offers significant advantages in terms of rate and reliability. We consider sharing the MIMO increased rate in wireless mesh networks (WMNs) links. Such sharing allows nodes in a WMN to concurrently meet more demanding communication requirements such as high data rates, increased transmission range, power savings and low dropping rates. In this paper, we propose

Abduladhim Ashtaiwi; Hossam S. Hassanein

2007-01-01

472

49 CFR 33.36 - Changes or cancellations of priority ratings and rated orders.  

Code of Federal Regulations, 2012 CFR

... false Changes or cancellations of priority ratings and rated orders. 33.36...Secretary of Transportation TRANSPORTATION PRIORITIES AND ALLOCATION SYSTEM Placement of...33.36 Changes or cancellations of priority ratings and rated orders. (a)...

2012-10-01

473

39 CFR 3010.28 - Maximum size of unused rate adjustment authority rate adjustments.  

Code of Federal Regulations, 2013 CFR

... POSTAL REGULATORY COMMISSION PERSONNEL REGULATION OF RATES FOR MARKET DOMINANT PRODUCTS Rules for Applying the Price Cap § 3010.28 Maximum size of unused rate adjustment authority rate adjustments. Unused rate adjustment authority...

2013-07-01

474

78 FR 283 - 2013 Rate Changes for the Basetime, Overtime, Holiday, and Laboratory Services Rates  

Federal Register 2010, 2011, 2012, 2013

...allowance rate) = $83.54. Laboratory Services Rate = The quotient...The calculation for the 2013 laboratory services rate per hour per...overtime, holiday, and laboratory services rates formulas...Register_Notices/index.asp. FSIS will also make...

2013-01-03

475

Entrainment Rates in POST Stratocumulus  

NASA Astrophysics Data System (ADS)

A recent field study (POST; Physics of Stratocumulus top; July-Aug., 2008) off the California Coast used the CIRPAS Twin Otter aircraft to observe mostly unbroken stratocumulus clouds (Sc). Seventeen flights were made in a quasi-Lagrangian horizontal pattern and in a vertical profiling pattern +/- 100 m about Sc top that was repeated numerous times. The aircraft carried a full complement of probes, including the high rate (1000-hz) UFT (ultra-fast temperature) and PVM (LWC and effective radius) probes both of which provided data within cloud and were located near the aircraft’s gust probe. The latter two probes were used to estimate the entrainment velocity (we) into the Sc using the “conditional sampling” approach. The range of we values fall within previous estimates of we, and examples of the measurements are presented. This we data set provides new insight on the entrainment process with findings including the following: About on half the POST flights the Sc showed entrainment behavior unlike that expected from previous applications of the “conditional sampling” method. Higher wind speeds and shear near Sc top generated significant turbulence both above and below the cloud-top interface causing the linear entrainment flux approximation near Sc top to be invalid. This behavior would also affect the “flux-jump” method used previously for estimating we., leading to questions about the validity of previous we measurements. In addition the required sharp jump at the interface of the entrainment scalar was not present in some cases. The “conditional sampling” method yields pdfs of the entrainment parcel length which are variable depending on the flight. The lengths are sufficiently large in some cases and are compatible with practical LES grid spacing suggesting a LES modeling and measurement comparison, where the more robust measurement is the entrainment flux into the POST Sc rather than the estimate of we.

Gerber, H. E.; Frick, G.

2010-12-01

476

1996 Wholesale Power and Transmission Rate Schedules.  

SciTech Connect

Bonneville Power Administration`s (BPA) 1996 Wholesale Power Rate Schedules, 1996 Ancillary Products and Services Rate Schedule, 1996 Transmission Rate Schedules, and General Rate Schedule Provisions, contained herein, were approved on an interim basis effective October 1, 1996. These rate schedules and provisions were approved by the Federal Energy Regulatory Commission (FERC), United States Department of Energy, in September 1996 (Docket Nos EF96-2011-000 and EF96f-2021-000). These rate schedules and General Rate Schedule Provisions were approved on a final basis by the FERC July 30, 1997, in Dept. of Energy--Bonneville Power Administration, Docket Nos. EF96-2011-000 and EF96-2021-000. Except as noted elsewhere, these 1996 rate schedules and provisions supersede BPA`s Wholesale Power Rate Schedules and General Rate Schedule Provisions, and Transmission Rate Schedules and General Transmission Rate Schedule Provisions, effective October 1, 1995. These rate schedules and general rate schedule provisions include all errata.

United States. Bonneville Power Administration.

1996-10-01

477

Managing the primary cesarean delivery rate.  

PubMed

One third of deliveries in the United States are by cesarean, a rate that far exceeds that recommended by professional organizations and experts. A dominant reason for the high overall cesarean rate is the rising primary cesarean rate. The high primary cesarean rate results from multiple factors, both clinical and nonclinical. This review outlines proposed interventions to lower the primary cesarean rate. We focus on those implementable at a facility level and would likely yield immediate results, including aligning provider incentives for vaginal birth, limiting elective induction of labor, and improving labor management of dystocia and abnormal fetal heart rate tracings. PMID:23090464

Branch, David Ware; Silver, Robert M

2012-12-01

478

7 CFR 983.253 - Assessment rate.  

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Assessment Rate § 983.253 Assessment...rate of $0.0005 per pound is established for California, Arizona, and New Mexico pistachios. (b) Each handler who...

2013-01-01

479

Dropout Rates in the United States: 1998.  

National Technical Information Service (NTIS)

The current report presents data for 1998 on high school dropout rates, and examines high school completion and graduation rates. In addition to extending time series data reported in earlier years, this report focuses on the characteristics of high schoo...

P. Kaufman J. Y. Kwon S. Klein C. D. Chapman

1999-01-01

480

7 CFR 755.7 - Transportation rates.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Transportation rates. 755.7 Section 755... SPECIAL PROGRAMS REIMBURSEMENT TRANSPORTATION COST PAYMENT PROGRAM FOR GEOGRAPHICALLY...FARMERS AND RANCHERS § 755.7 Transportation rates. (a) Payments may be...

2013-01-01

481

7 CFR 1435.101 - Loan rates.  

Code of Federal Regulations, 2013 CFR

...AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Sugar Loan Program § 1435.101 Loan rates. (a) The national average loan rate for raw cane sugar produced from domestically grown sugarcane...

2013-01-01

482

7 CFR 959.237 - Assessment rate.  

Code of Federal Regulations, 2013 CFR

...NUTS), DEPARTMENT OF AGRICULTURE ONIONS GROWN IN SOUTH TEXAS Assessment Rates § 959.237 Assessment rate. On...of $0.025 per 50-pound equivalent is established for South Texas onions. [74 FR 38508, Aug. 4,...

2013-01-01

483

25 CFR 700.717 - Stocking rate.  

Code of Federal Regulations, 2013 CFR

...HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES New Lands Grazing § 700.717 Stocking rate. The Commissioner will determine livestock carrying capacity for each range unit and set the stocking rate and adjust that...

2013-04-01

484

Interest Rate, Transaction Costs and Financial Innovations.  

National Technical Information Service (NTIS)

Fragmentation of the capital market, that is, the phenomena of different markets for different products, as it occurs in the LDCs is generally attributed to high interest rates. The crucial variable in determining these rates is transaction costs (both ad...

V. V. Bhatt

1979-01-01

485

Peer and Supervisory Ratings of Research Scientists.  

National Technical Information Service (NTIS)

A sample of 103 government research scientists was used to compare two performance evaluation systems currently used in a Federal agency for its research personnel. The two systems, supervisory ratings and peer ratings, were compared in terms of their res...

G. D. Kissler D. M. Nebeker

1979-01-01

486

78 FR 39280 - Integrated System Power Rates  

Federal Register 2010, 2011, 2012, 2013

...facilities. The Administrator of Southwestern...proposed Integrated System rates, which are...guidelines, the Administrator of Southwestern...using existing system rates.\\1\\ This...proceeding, the Administrator will submit the finalized Integrated System Power...

2013-07-01

487

7 CFR 930.200 - Assessment rate.  

Code of Federal Regulations, 2013 CFR

...ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW YORK, PENNSYLVANIA, OREGON, UTAH, WASHINGTON, AND WISCONSIN Assessment Rates § 930.200 Assessment rate. On and after...

2013-01-01

488

15 CFR 700.11 - Priority ratings.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Priority ratings. 700.11 Section 700.11...SECURITY INDUSTRIAL BASE REGULATIONS DEFENSE PRIORITIES AND ALLOCATIONS SYSTEM Industrial Priorities § 700.11 Priority ratings....

2009-01-01

489

46 CFR 111.40-13 - Rating.  

Code of Federal Regulations, 2012 CFR

...OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Panelboards § 111.40-13 Rating. Each panelboard must have a current rating not less than the feeder circuit...

2012-10-01

490

7 CFR 948.216 - Assessment rate.  

Code of Federal Regulations, 2013 CFR

...NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Accounting and Collections § 948.216 Assessment rate...assessment rate of $0.0051 per hundredweight is established for Colorado Area No. 2 potatoes. [68 FR 53283, Sept. 10,...

2013-01-01

491

7 CFR 948.215 - Assessment rate.  

Code of Federal Regulations, 2013 CFR

...NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Accounting and Collections § 948.215 Assessment rate...assessment rate of $0.02 per hundredweight is established for Colorado Area No. 3 potatoes. [70 FR 36816, June 27,...

2013-01-01

492

Measuring Star Formation Rates in Blue Galaxies.  

National Technical Information Service (NTIS)

The problems associated with measurements of star formation rates in galaxies are briefly reviewed, and specific models are presented for determinations of current star formation rates from H alpha and Far Infrared (FIR) luminosities. The models are appli...

J. S. Gallagher D. A. Hunter

1987-01-01

493

Prostate Cancer Rates by Race and Ethnicity  

MedlinePLUS

... by white, Hispanic, Asian/Pacific Islander, and American Indian/Alaska Native men. Prostate Cancer Incidence Rates* by ... race categories (white, black, Asian/Pacific Islander, American Indian/Alaska Native). Death Rates by Race/Ethnicity From ...

494

Cervical Cancer Rates by Race and Ethnicity  

MedlinePLUS

... Doing Related Links Inside Knowledge Campaign Survivor Stories Television Public Service ... Cancer Rates by Race and Ethnicity The rate of women getting cervical cancer or dying from cervical cancer ...

495

Ovarian Cancer Rates by Race and Ethnicity  

MedlinePLUS

... Doing Related Links Inside Knowledge Campaign Survivor Stories Television Public Service ... Cancer Rates by Race and Ethnicity The rate of women getting ovarian cancer or dying from ovarian cancer ...

496

HYDROXYL RADICAL RATE CONSTANT INTERCOMPARISON STUDY  

EPA Science Inventory

An intercomparison study was conducted to evaluate the OH rate constant measurement protocol developed by researchers at the University of California at Riverside. Researchers used the protocol to measure the room temperature OH rate constants for ethane, benzene, chlorobenzene, ...

497

Charge Tunneling Rates in Ultrasmall Junctions  

Microsoft Academic Search

1. Introduction 2. Description of the environment 3. Electron tunneling rates for single tunnel junctions 4. Examples of electromagnetic environments 5. Tunneling rates in Josephson junctions 6. Double junction and single electron transistor 7. Microscopic foundation

Gert-Ludwig Ingold; Yu. V. Nazarov

2005-01-01

498

78 FR 62627 - Sam Rayburn Dam Rate  

Federal Register 2010, 2011, 2012, 2013

...Southwestern Power Administration Sam Rayburn Dam Rate AGENCY: Southwestern Power Administration...increases the power rate for the Sam Rayburn Dam (Rayburn) project pursuant to the Rayburn...Hydro Power and Energy Sold to Sam Rayburn Dam Electric Cooperative, Inc....

2013-10-22

499

Ammunition Reconfiguration Module Operating Characteristics and Rates.  

National Technical Information Service (NTIS)

In an earlier research study report entitled: 'Wargaming Analysis of Ammunition Flow Rates', Armament Systems, Inc., (ASI) developed a series of detailed matrices which portrayed daily ammunition expenditure rates for eleven different combat battalion siz...

1987-01-01

500

Rate of Nucleation in Condensed Systems  

Microsoft Academic Search

On the basis of the nucleation theory developed by Volmer, Becker, and co-workers, and the theory of absolute reaction rates, an expression is derived for the absolute rate of nucleation in condensed systems.

D. Turnbull; J. C. Fisher

1949-01-01