A Unified Global Reference Frame of Vertical Crustal Movements by Satellite Laser Ranging

PubMed Central

Zhu, Xinhui; Wang, Ren; Sun, Fuping; Wang, Jinling

2016-01-01

Crustal movement is one of the main factors influencing the change of the Earth system, especially in its vertical direction, which affects people’s daily life through the frequent occurrence of earthquakes, geological disasters, and so on. In order to get a better study and application of the vertical crustal movement, as well as its changes, the foundation and prerequisite areto devise and establish its reference frame; especially, a unified global reference frame is required. Since SLR (satellite laser ranging) is one of the most accurate space techniques for monitoring geocentric motion and can directly measure the ground station’s geocentric coordinates and velocities relative to the centre of the Earth’s mass, we proposed to take the vertical velocity of the SLR technique in the ITRF2008 framework as the reference frame of vertical crustal motion, which we defined as the SLR vertical reference frame (SVRF). The systematic bias between other velocity fields and the SVRF was resolved by using the GPS (Global Positioning System) and VLBI (very long baseline interferometry) velocity observations, and the unity of other velocity fields and SVRF was realized, as well. The results show that it is feasible and suitable to take the SVRF as a reference frame, which has both geophysical meanings and geodetic observations, so we recommend taking the SLR vertical velocity under ITRF2008 as the global reference frame of vertical crustal movement. PMID:26867197

Location memory biases reveal the challenges of coordinating visual and kinesthetic reference frames

PubMed Central

Simmering, Vanessa R.; Peterson, Clayton; Darling, Warren; Spencer, John P.

2008-01-01

Five experiments explored the influence of visual and kinesthetic/proprioceptive reference frames on location memory. Experiments 1 and 2 compared visual and kinesthetic reference frames in a memory task using visually-specified locations and a visually-guided response. When the environment was visible, results replicated previous findings of biases away from the midline symmetry axis of the task space, with stability for targets aligned with this axis. When the environment was not visible, results showed some evidence of bias away from a kinesthetically-specified midline (trunk anterior–posterior [a–p] axis), but there was little evidence of stability when targets were aligned with body midline. This lack of stability may reflect the challenges of coordinating visual and kinesthetic information in the absence of an environmental reference frame. Thus, Experiments 3–5 examined kinesthetic guidance of hand movement to kinesthetically-defined targets. Performance in these experiments was generally accurate with no evidence of consistent biases away from the trunk a–p axis. We discuss these results in the context of the challenges of coordinating reference frames within versus between multiple sensori-motor systems. PMID:17703284

Linking HIPPARCOS to the Extragalactic Reference Frame Part 5 OF 6, Newc, Cycle 2,CONTINUATION of 2565-HIGH

NASA Astrophysics Data System (ADS)

Hemenway, Paul

1991-07-01

Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

Quantum mechanics in noninertial reference frames: Relativistic accelerations and fictitious forces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klink, W.H., E-mail: william-klink@uiowa.edu; Wickramasekara, S., E-mail: wickrama@grinnell.edu

2016-06-15

One-particle systems in relativistically accelerating reference frames can be associated with a class of unitary representations of the group of arbitrary coordinate transformations, an extension of the Wigner–Bargmann definition of particles as the physical realization of unitary irreducible representations of the Poincaré group. Representations of the group of arbitrary coordinate transformations become necessary to define unitary operators implementing relativistic acceleration transformations in quantum theory because, unlike in the Galilean case, the relativistic acceleration transformations do not themselves form a group. The momentum operators that follow from these representations show how the fictitious forces in noninertial reference frames are generated inmore » quantum theory.« less

U.S. Geological Survey National Computer Technology Meeting: Program and Abstracts, Norfolk, Virginia, May 17-22, 1992

DTIC Science & Technology

1992-05-01

formats, and character formats that can easily integrate graphics and text into one document. FrameMaker is one of few ERP software programs that has...easier and faster using ERP software. The DIS-II ERP software program is FrameMaker by Frame Technology, Incorporated. FrameMaker uses the X window...functions, calculus, relations, and other complicated math applications. FrameMaker permits the user to define formats for master pages, reference pages

The Gaia inertial reference frame and the tilting of the Milky Way disk

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perryman, Michael; Spergel, David N.; Lindegren, Lennart, E-mail: mac.perryman@gmail.com

2014-07-10

While the precise relationship between the Milky Way disk and the symmetry planes of the dark matter halo remains somewhat uncertain, a time-varying disk orientation with respect to an inertial reference frame seems probable. Hierarchical structure formation models predict that the dark matter halo is triaxial and tumbles with a characteristic rate of ∼2 rad H{sub 0}{sup −1} (∼30 μas yr{sup –1}). These models also predict a time-dependent accretion of gas, such that the angular momentum vector of the disk should be misaligned with that of the halo. These effects, as well as tidal effects of the LMC, will resultmore » in the rotation of the angular momentum vector of the disk population with respect to the quasar reference frame. We assess the accuracy with which the positions and proper motions from Gaia can be referred to a kinematically non-rotating system, and show that the spin vector of the transformation from any rigid self-consistent catalog frame to the quasi-inertial system defined by quasars should be defined to better than 1 μas yr{sup –1}. Determination of this inertial frame by Gaia will reveal any signature of the disk orientation varying with time, improve models of the potential and dynamics of the Milky Way, test theories of gravity, and provide new insights into the orbital evolution of the Sagittarius dwarf galaxy and the Magellanic Clouds.« less

A variational approach to dynamics of flexible multibody systems

NASA Technical Reports Server (NTRS)

Wu, Shih-Chin; Haug, Edward J.; Kim, Sung-Soo

1989-01-01

This paper presents a variational formulation of constrained dynamics of flexible multibody systems, using a vector-variational calculus approach. Body reference frames are used to define global position and orientation of individual bodies in the system, located and oriented by position of its origin and Euler parameters, respectively. Small strain linear elastic deformation of individual components, relative to their body references frames, is defined by linear combinations of deformation modes that are induced by constraint reaction forces and normal modes of vibration. A library of kinematic couplings between flexible and/or rigid bodies is defined and analyzed. Variational equations of motion for multibody systems are obtained and reduced to mixed differential-algebraic equations of motion. A space structure that must deform during deployment is analyzed, to illustrate use of the methods developed.

The error of L5/S1 joint moment calculation in a body-centered non-inertial reference frame when the fictitious force is ignored.

PubMed

Xu, Xu; Faber, Gert S; Kingma, Idsart; Chang, Chien-Chi; Hsiang, Simon M

2013-07-26

In ergonomics studies, linked segment models are commonly used for estimating dynamic L5/S1 joint moments during lifting tasks. The kinematics data input to these models are with respect to an arbitrary stationary reference frame. However, a body-centered reference frame, which is defined using the position and the orientation of human body segments, is sometimes used to conveniently identify the location of the load relative to the body. When a body-centered reference frame is moving with the body, it is a non-inertial reference frame and fictitious force exists. Directly applying a linked segment model to the kinematics data with respect to a body-centered non-inertial reference frame will ignore the effect of this fictitious force and introduce errors during L5/S1 moment estimation. In the current study, various lifting tasks were performed in the laboratory environment. The L5/S1 joint moments during the lifting tasks were calculated by a linked segment model with respect to a stationary reference frame and to a body-centered non-inertial reference frame. The results indicate that applying a linked segment model with respect to a body-centered non-inertial reference frame will result in overestimating the peak L5/S1 joint moments of the coronal plane, sagittal plane, and transverse plane during lifting tasks by 78%, 2%, and 59% on average, respectively. The instant when the peak moment occurred was delayed by 0.13, 0.03, and 0.09s on average, correspondingly for the three planes. The root-mean-square errors of the L5/S1 joint moment for the three planes are 21Nm, 19Nm, and 9Nm, correspondingly. Copyright © 2013 Elsevier Ltd. All rights reserved.

Integrating Analysis Goals for EOP, CRF and TRF

NASA Technical Reports Server (NTRS)

Ma, Chopo; MacMillan, Daniel; Petrov, Leonid

2002-01-01

In a simplified, idealized way the TRF (Terrestrial Reference Frame) can be considered a set of positions at epoch and corresponding linear rates of change while the CRF (Celestial Reference Frame) is a set of fixed directions in space. VLBI analysis can be optimized for CRF and TRF separately while handling some of the complexity of geodetic and astrometric reality. For EOP (Earth Orientation Parameter) time series both CRF and TRF should be accurate at the epoch of interest and well defined over time. The optimal integration of EOP, TRF and CRF in a single VLBI solution configuration requires a detailed consideration of the data set and the possibly conflicting nature of the reference frames. A possible approach for an integrated analysis is described.

Quantum frames

NASA Astrophysics Data System (ADS)

Brown, Matthew J.

2014-02-01

The framework of quantum frames can help unravel some of the interpretive difficulties i the foundation of quantum mechanics. In this paper, I begin by tracing the origins of this concept in Bohr's discussion of quantum theory and his theory of complementarity. Engaging with various interpreters and followers of Bohr, I argue that the correct account of quantum frames must be extended beyond literal space-time reference frames to frames defined by relations between a quantum system and the exosystem or external physical frame, of which measurement contexts are a particularly important example. This approach provides superior solutions to key EPR-type measurement and locality paradoxes.

Time-Dependent Selection of an Optimal Set of Sources to Define a Stable Celestial Reference Frame

NASA Technical Reports Server (NTRS)

Le Bail, Karine; Gordon, David

2010-01-01

Temporal statistical position stability is required for VLBI sources to define a stable Celestial Reference Frame (CRF) and has been studied in many recent papers. This study analyzes the sources from the latest realization of the International Celestial Reference Frame (ICRF2) with the Allan variance, in addition to taking into account the apparent linear motions of the sources. Focusing on the 295 defining sources shows how they are a good compromise of different criteria, such as statistical stability and sky distribution, as well as having a sufficient number of sources, despite the fact that the most stable sources of the entire ICRF2 are mostly in the Northern Hemisphere. Nevertheless, the selection of a stable set is not unique: studying different solutions (GSF005a and AUG24 from GSFC and OPA from the Paris Observatory) over different time periods (1989.5 to 2009.5 and 1999.5 to 2009.5) leads to selections that can differ in up to 20% of the sources. Observing, recording, and network improvement are some of the causes, showing better stability for the CRF over the last decade than the last twenty years. But this may also be explained by the assumption of stationarity that is not necessarily right for some sources.

Observable Zitterbewegung in curved spacetimes

NASA Astrophysics Data System (ADS)

Kobakhidze, Archil; Manning, Adrian; Tureanu, Anca

2016-06-01

Zitterbewegung, as it was originally described by Schrödinger, is an unphysical, non-observable effect. We verify whether the effect can be observed in non-inertial reference frames/curved spacetimes, where the ambiguity in defining particle states results in a mixing of positive and negative frequency modes. We explicitly demonstrate that such a mixing is in fact necessary to obtain the correct classical value for a particle's velocity in a uniformly accelerated reference frame, whereas in cosmological spacetime a particle does indeed exhibit Zitterbewegung.

The Current Status and Tendency of China Millimeter Coordinate Frame Implementation and Maintenance

NASA Astrophysics Data System (ADS)

Cheng, P.; Cheng, Y.; Bei, J.

2017-12-01

China Geodetic Coordinate System 2000 (CGCS2000) was first officially declared as the national standard coordinate system on July 1, 2008. This reference frame was defined in the ITRF97 frame at epoch 2000.0 and included 2600 GPS geodetic control points. The paper discusses differences between China Geodetic Coordinate System 2000 (CGCS2000) and later updated ITRF versions, such as ITRF2014,in terms of technical implementation and maintenance. With the development of the Beidou navigation satellite system, especially third generation of BDS with signal global coverage in the future, and with progress of space geodetic technology, it is possible for us to establish a global millimeter-level reference frame based on space geodetic technology including BDS. The millimeter reference frame implementation concerns two factors: 1) The variation of geocenter motion estimation, and 2) the site nonlinear motion modeling. In this paper, the geocentric inversion methods are discussed and compared among results derived from various technical methods. Our nonlinear site movement modeling focuses on singular spectrum analysis method, which is of apparent advantages over earth physical effect modeling. All presented in the paper expected to provide reference to our future CGCS2000 maintenance.

Design and Principles Enabling the Space Reference FOM

NASA Technical Reports Server (NTRS)

Moeller, Bjoern; Dexter, Dan; Madden, Michael; Crues, Edwin Z.; Garro, Alfredo; Skuratovskiy, Anton

2017-01-01

A first complete draft of the Simulation Interoperability Standards Organization (SISO) Space Reference Federation Object Model (FOM) has now been produced. This paper provides some insights into its capabilities and discusses the opportunity for reuse in other domains. The focus of this first version of the standard is execution control, time management and coordinate systems, well-known reference frames, as well as some basic support for physical entities. The biggest part of the execution control is the coordinated start-up process. This process contains a number of steps, including checking of required federates, handling of early versus late joiners, sharing of federation wide configuration data and multi-phase initialization. An additional part of Execution Control is the coordinated and synchronized transition between Run mode, Freeze mode and Shutdown. For time management, several time lines are defined, including real-time, scenario time, High Level Architecture (HLA) logical time and physical time. A strategy for mixing simulations that use different time steps is introduced, as well as an approach for finding common boundaries for fully synchronized freeze. For describing spatial information, a mechanism with a set of reference frames is specified. Each reference frame has a position and orientation related to a parent reference frame. This makes it possible for federates to perform calculations in reference frames that are convenient to them. An operation on the Moon can be performed using lunar coordinates whereas an operation on Earth can be performed using Earth coordinates. At the same time, coordinates in one reference frame have an unambiguous relationship to a coordinate in another reference frame. While the Space Reference FOM is originally being developed for Space operations, the authors believe that many parts of it can be reused for any simulation that has a focus on physical processes with one or more coordinate systems, and require high fidelity and repeatability.

Facial measurements for frame design.

PubMed

Tang, C Y; Tang, N; Stewart, M C

1998-04-01

Anthropometric data for the purpose of spectacle frame design are scarce in the literature. Definitions of facial features to be measured with existing systems of facial measurement are often not specific enough for frame design and manufacturing. Currently, for individual frame design, experienced personnel collect data with facial rules or instruments. A new measuring system is proposed, making use of a template in the form of a spectacle frame. Upon fitting the template onto a subject, most of the measuring references can be defined. Such a system can be administered by lesser-trained personnel and can be used for researches covering a larger population.

Global reference frame: Intercomparison of results (SLR, VLBI and GPS)

NASA Technical Reports Server (NTRS)

Ma, Chopo; Watkins, Michael M.; Heflin, M.

1994-01-01

The terrestrial reference frame (TRF) is realized by a set of positions and velocities derived from a combination of the three space geodetic techniques, SLR, VLBI and GPS. The standard International TRF is constructed by the International Earth Rotation Service in such a way that it is stable with time and the addition of new data. An adopted model for overall plate motion, NUVEL-1 NNR, defines the conceptual reference frame in which all the plates are moving. In addition to the measurements made between reference points within the space geodetic instruments, it is essential to have accurate, documented eccentricity measurements from the instrument reference points to ground monuments. Proper local surveys between the set of ground monuments at a site are also critical for the use of the space geodetic results. Eccentricities and local surveys are, in fact, the most common and vexing sources of error in the use of the TRF for such activities as collocation and intercomparison.

Radio-planetary from tie from Phobos-2 VLBI data

NASA Technical Reports Server (NTRS)

Hildebrand, C. E.; Iijima, B. A.; Kroger, P. M.; Folkner, W. M.; Edwards, C. D.

1994-01-01

In an ongoing effort to improve the knowledge of the relative orientation (the 'frame tie') of the planetary ephemeris reference frame used in deep navigation and a second reference frame that is defined by the coordinates of a set of extragalactic radio sources, VLBI observations of the Soviet Phobos-2 spacecraft and nearby (in angle) radio sources were obtained at two epochs in 1989, shortly after the spacecraft entered orbit about Mars. The frame tie is an important systematic error source affecting both interplanetary navigation and the process of improving the theory of the Earth's orientation. The data from a single Phobos-2 VLBI session measure one component of the direction vector from Earth to Mars in the frame of the extragalactic radio sources (the 'radio frame'). The radio frame has been shown to be stable and internally consistent with an accuracy of 5 nrad. The planetary ephemeris reference frame has an internal consistency of approximately 15 nrad. The planetary and radio source reference frames were aligned prior to 1989 and measurements of occulations of the radio source 3C273 by the Moon. The Phobos-2 VLBI measurements provide improvement in the accuracy of two of the three angles describing a general rotation between the planetary and radio reference frames. A complete set of measurements is not available because data acquisition was terminated prematurely by loss of spacecraft. The analysis of the two Phobos-2 VLBI data sets indicates that, in the directions of the two rotation components determined by these data, the JPL planetary ephemeris DE200 is aligned with the radio frame as adopted by the International Earth Rotation Service within an accuracy of 20-40 nrad, depending on direction. The limiting errors in the solutions for these offsets are spacecraft trajectory (20 nrad), instrumental biases (19 nrad), and dependence of quasar coordinates on observing frequency (24 nrad).

Gravity Influences the Visual Representation of Object Tilt in Parietal Cortex

PubMed Central

Angelaki, Dora E.

2014-01-01

Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an “earth-vertical” direction. PMID:25339732

Emotional valence and contextual affordances flexibly shape approach-avoidance movements

PubMed Central

Saraiva, Ana Carolina; Schüür, Friederike; Bestmann, Sven

2013-01-01

Behavior is influenced by the emotional content—or valence—of stimuli in our environment. Positive stimuli facilitate approach, whereas negative stimuli facilitate defensive actions such as avoidance (flight) and attack (fight). Facilitation of approach or avoidance movements may also be influenced by whether it is the self that moves relative to a stimulus (self-reference) or the stimulus that moves relative to the self (object-reference), adding flexibility and context-dependence to behavior. Alternatively, facilitation of approach avoidance movements may happen in a pre-defined and muscle-specific way, whereby arm flexion is faster to approach positive (e.g., flexing the arm brings a stimulus closer) and arm extension faster to avoid negative stimuli (e.g., extending the arm moves the stimulus away). While this allows for relatively fast responses, it may compromise the flexibility offered by contextual influences. Here we asked under which conditions approach-avoidance actions are influenced by contextual factors (i.e., reference-frame). We manipulated the reference-frame in which actions occurred by asking participants to move a symbolic manikin (representing the self) toward or away from a positive or negative stimulus, and move a stimulus toward or away from the manikin. We also controlled for the type of movements used to approach or avoid in each reference. We show that the reference-frame influences approach-avoidance actions to emotional stimuli, but additionally we find muscle-specificity for negative stimuli in self-reference contexts. We speculate this muscle-specificity may be a fast and adaptive response to threatening stimuli. Our results confirm that approach-avoidance behavior is flexible and reference-frame dependent, but can be muscle-specific depending on the context and valence of the stimulus. Reference-frame and stimulus-evaluation are key factors in guiding approach-avoidance behavior toward emotional stimuli in our environment. PMID:24379794

The Modulated Annual Cycle: An Alternative Reference Frame for Climate Anomalies

NASA Astrophysics Data System (ADS)

Wu, Z.

2007-12-01

In climate science, an anomaly is the deviation of a quantity from its annual cycle (AC). There are many ways to define annual cycle. Traditionally, the annual cycle is taken to be an exact repetition of itself year after year. This stationary annual cycle may not reflect well the intrinsic nonlinearity of the climate system, especially under external forcing. In this study, we have reexamined the reference frame for anomalies by reexamining the annual cycle. We propose an alternative reference frame, the modulated annual cycle (MAC) that allows the annual cycle to change from year to year, for defining anomalies. In order for this alternative reference frame to be useful, we need to be able to define the instantaneous annual cycle. We therefore also introduce a new method to extract the MAC from climatic data. In the presence of an MAC, modulated in both amplitude and frequency, we can then define an alternative version of an anomaly, this time with respect to the instantaneous MAC rather than a permanent and unchanging AC. Based on this alternative definition of anomalies, we reexamine some familiar physical processes: in particular, the sea surface temperature (SST) reemergence and the ENSO phase locking to the annual cycle. We find that the re-emergence mechanism may be alternatively interpreted as an explanation of the change of the annual cycle instead of the interannual to interdecadal persistence of SST anomalies. We also find that the ENSO phase locking can largely be attributed to the residual annual cycle (the difference of the MAC and the corresponding traditional annual cycle) contained in the traditional anomaly, and, therefore, can be alternatively interpreted as a part of the annual cycle phase locked to the annual cycle itself. Two additional examples are also presented of the implications of using a MAC against which to define anomalies. We show that using MAC as a reference framework for anomaly can bypass the difficulty brought by concepts such as "decadal variability of summer (or winter) climate" for understanding the low-frequency variability of the climate system. We also point out the drawbacks related to the stationary assumption in previous studies of extreme weather and climate and propose instead the appropriateness of choosing a non-stationary framework to study extreme weather and climate events. The concept of an amplitude and frequency modulated annual cycle, a method to extract it, and its implications for the interpretation of physical processes, all may contribute potentially to a more consistent and fruitful way of examining past and future climate variability and change.

The modulated annual cycle: an alternative reference frame for climate anomalies

NASA Astrophysics Data System (ADS)

Wu, Zhaohua; Schneider, Edwin K.; Kirtman, Ben P.; Sarachik, E. S.; Huang, Norden E.; Tucker, Compton J.

2008-12-01

In climate science, an anomaly is the deviation of a quantity from its annual cycle. There are many ways to define annual cycle. Traditionally, this annual cycle is taken to be an exact repeat of itself year after year. This stationary annual cycle may not reflect well the intrinsic nonlinearity of the climate system, especially under external forcing. In this paper, we re-examine the reference frame for anomalies by re-examining the annual cycle. We propose an alternative reference frame for climate anomalies, the modulated annual cycle (MAC) that allows the annual cycle to change from year to year, for defining anomalies. In order for this alternative reference frame to be useful, we need to be able to define the instantaneous annual cycle: we therefore also introduce a new method to extract the MAC from climatic data. In the presence of a MAC, modulated in both amplitude and frequency, we can then define an alternative version of an anomaly, this time with respect to the instantaneous MAC rather than a permanent and unchanging AC. Based on this alternative definition of anomalies, we re-examine some familiar physical processes: in particular SST re-emergence and ENSO phase locking to the annual cycle. We find that the re-emergence mechanism may be alternatively interpreted as an explanation of the change of the annual cycle instead of an explanation of the interannual to interdecadal persistence of SST anomalies. We also find that the ENSO phase locking can largely be attributed to the residual annual cycle (the difference of the MAC and the corresponding traditional annual cycle) contained in the traditional anomaly, and, therefore, can be alternatively interpreted as a part of the annual cycle phase locked to the annual cycle itself. In addition to the examples of reinterpretation of physics of well known climate phenomena, we also present an example of the implications of using a MAC against which to define anomalies. We show that using MAC as a reference framework for anomaly can bypass the difficulty brought by concepts such as “decadal variability of summer (or winter) climate” for understanding the low-frequency variability of the climate system. The concept of an amplitude and frequency modulated annual cycle, a method to extract it, and its implications for the interpretation of physical processes, all may contribute potentially to a more consistent and fruitful way of examining past and future climate variability and change.

Different strategies for spatial updating in yaw and pitch path integration

PubMed Central

Goeke, Caspar M.; König, Peter; Gramann, Klaus

2013-01-01

Research in spatial navigation revealed the existence of discrete strategies defined by the use of distinct reference frames during virtual path integration. The present study investigated the distribution of these navigation strategies as a function of gender, video gaming experience, and self-estimates of spatial navigation abilities in a population of 300 subjects. Participants watched videos of virtual passages through a star-field with one turn in either the horizontal (yaw) or the vertical (pitch) axis. At the end of a passage they selected one out of four homing arrows to indicate the initial starting location. To solve the task, participants could employ two discrete strategies, navigating within either an egocentric or an allocentric reference frame. The majority of valid subjects (232/260) consistently used the same strategy in more than 75% of all trials. With that approach 33.1% of all participants were classified as Turners (using an egocentric reference frame on both axes) and 46.5% as Non-turners (using an allocentric reference frame on both axes). 9.2% of all participants consistently used an egocentric reference frame in the yaw plane but an allocentric reference frame in the pitch plane (Switcher). Investigating the influence of gender on navigation strategies revealed that females predominantly used the Non-turner strategy while males used both the Turner and the Non-turner strategy with comparable probabilities. Other than expected, video gaming experience did not influence strategy use. Based on a strong quantitative basis with the sample size about an order of magnitude larger than in typical psychophysical studies these results demonstrate that most people reliably use one out of three possible navigation strategies (Turners, Non-turners, Switchers) for spatial updating and provides a sound estimate of how those strategies are distributed within the general population. PMID:23412683

Contribution of TIGA reprocessing to the ITRF densification

NASA Astrophysics Data System (ADS)

Rudenko, S.; Dähnn, M.; Gendt, G.; Brandt, A.; Nischan, T.

2009-04-01

Analysis of tide gauge measurements with the purpose of sea level change investigations requires a well defined reference frame. Such reference frame can be realized through precise positions of GPS stations located at or near tide gauges (TIGA stations) and analyzed within the IGS GPS Tide Gauge Benchmark Monitoring Pilot Project (TIGA). To tie this reference frame to the International Terrestrial Reference Frame (ITRF), one should process simultaneously GPS data from TIGA and IGS stations included in the ITRF. A time series of GPS station positions has been recently derived by reprocessing GPS data from about 400 GPS stations globally distributed covering totally time span from 1998 till 2008 using EPOS-Potsdam software developed at GFZ and improved in the recent years. The analysis is based on the use of IERS Conventions 2003, ITRF2005 as a priori reference frame, FES2004 ocean tide loading model, absolute phase centre variations for GPS satellite transmit and ground receive antennae and other models. About 220 stations of the solution are IGS ones and about 180 are TIGA GPS stations that are not IGS ones. The solution includes weekly coordinates of GPS stations, daily values of the Earth rotation parameters and their rates, as well as satellite antenna offsets. On the other hand, our new solution can contribute to the ITRF densification by providing positions of about 200 stations being not present in ITRF2005. The solution can be also used for the integration of regional frames. The paper presents the results of the analysis and the comparison of our solution with ITRF2005 and the solutions of other TIGA and IGS Analysis Centres.

Modernizing the National Spatial Reference System

NASA Astrophysics Data System (ADS)

Smith, D. A.

2016-12-01

The National Spatial Reference System (NSRS) is that system of datums, reference frames, shorelines, software and standards which serve the entire federal civilian geospatial community. It is the mission of the National Geodetic Survey (NGS) to define, maintain and provide access to the NSRS. Currently the NSRS contains three geometric reference frames (NAD 83(2011), NAD 83(PA11) and NAD 83(MA11)), one dynamic height datum (IGLD 85) and 6 vertical datums (NAVD 88, PRVD02, ASVD02, NMVD03, GUVD04, VIVD09). All of these datums are built on aging technology and contain systematic errors that grow more noticeable as access to accurate positioning becomes more widespread. It was determined by NGS in 2007 that this was not sustainable and as such, all datums and reference frames are scheduled to be replaced in 2022. [At the time of this abstract, the exact names of the replacements are being finalized and are expected to be announced by the AGU fall meeting.] Replacing the official datums and reference frames requires a carefully coordinated effort of dozens of interrelated technical projects spanning years (over a decade in some cases) and involving a majority of NGS employees. This talk will cover the plans thus far, projects completed, projects underway and will summarize the NSRS as it is expected to look and be accessed in 2022 and beyond.

Syntax "and" Semantics: A Teaching Model.

ERIC Educational Resources Information Center

Wolfe, Frank

In translating perception into written language, a child must learn an encoding process which is a continuation of the process of improving sensing of the world around him or her. To verbalize an object (a perception) we use frames which name a referent, locate the referent in space and time, identify its appearance and behavior, and define terms…

Gravity influences the visual representation of object tilt in parietal cortex.

PubMed

Rosenberg, Ari; Angelaki, Dora E

2014-10-22

Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an "earth-vertical" direction. Copyright © 2014 the authors 0270-6474/14/3414170-11$15.00/0.

Four dimensional studies in earth space

NASA Technical Reports Server (NTRS)

Mather, R. S.

1972-01-01

A system of reference which is directly related to observations, is proposed for four-dimensional studies in earth space. Global control network and polar wandering are defined. The determination of variations in the earth's gravitational field with time also forms part of such a system. Techniques are outlined for the unique definition of the motion of the geocenter, and the changes in the location of the axis of rotation of an instantaneous earth model, in relation to values at some epoch of reference. The instantaneous system referred to is directly related to a fundamental equation in geodynamics. The reference system defined would provide an unambiguous frame for long period studies in earth space, provided the scale of the space were specified.

Focus control system for stretched-membrane mirror module

DOEpatents

Butler, B.L.; Beninga, K.J.

1991-05-21

A focus control system dynamically sets and controls the focal length of a reflective membrane supported between a perimeter frame. A rear membrane is also supported between the perimeter frame rearward and spaced apart from a back side of the reflective membrane. The space between the membranes defines a plenum space into which a mass of gas at a first pressure is inserted. The pressure differential between the first pressure and an external pressure, such as the atmospheric pressure, causes the reflective membrane to assume a first curvature relative to a reference plane associated with the perimeter frame. This curvature defines the focal length of the reflective membrane. The focal length is dynamically controlled by changing the volume of the plenum space, thereby changing the first pressure. The system can be used to change or maintain the pressure differential and hence the front membrane curvature. The plenum volume is changed by pushing or pulling on a central section of the rear membrane using a suitable actuator. Sensing means continuously sense the location of the reflective membrane relative to the reference plane. This sensed position is compared to a reference position, and a resulting error signal, comprising the difference between the sensed position and reference position, drives the actuator in a direction to minimize the difference. A vent value compensates for temperature changes or leaks in the closed volume by allowing the pressure differential to be adjusted as required to center the working range of the actuator about the desired focal length. 13 figures.

Focus control system for stretched-membrane mirror module

DOEpatents

Butler, Barry L.; Beninga, Kelly J.

1991-01-01

A focus control system dynamically sets and controls the focal length of a reflective membrane supported between a perimeter frame. A rear membrane is also supported between the perimeter frame rearward and spaced apart from a back side of the reflective membrane. The space between the membranes defines a plenum space into which a mass of gas at a first pressure is inserted. The pressure differential between the first pressure and an external pressure, such as the atmospheric pressure, causes the reflective membrane to assume a first curvature relative to a reference plane associated with the perimeter frame. This curvature defines the focal length of the reflective membrane. The focal length is dynamically controlled by changing the volume of the plenum space, thereby changing the first pressure. The system can be used to change or maintain the pressure differential and hence the front membrane curvature. The plenum volume is changed by pushing or pulling on a central section of the rear membrane using a suitable actuator. Sensing means continuously sense the location of the reflective membrane relative to the reference plane. This sensed position is compared to a reference position, and a resulting error signal, comprising the difference between the sensed position and reference position, drives the actuator in a direction to minimize the difference. A vent value compensates for temperature changes or leaks in the closed volume by allowing the pressure differential to be adjusted as required to center the working range of the actuator about the desired focal length.

Reference coordinate systems: An update. Supplement 11

NASA Technical Reports Server (NTRS)

Mueller, Ivan I.

1988-01-01

A common requirement for all geodetic investigations is a well-defined coordinate system attached to the earth in some prescribed way, as well as a well-defined inertial coordinate system in which the motions of the terrestrial frame can be monitored. The paper deals with the problems encountered when establishing such coordinate systems and the transformations between them. In addition, problems related to the modeling of the deformable earth are discussed. This paper is an updated version of the earlier work, Reference Coordinate Systems for Earth Dynamics: A Preview, by the author.

First results of the Nordic and Baltic GNSS Analysis Centre

NASA Astrophysics Data System (ADS)

Lahtinen, Sonja; Pasi, Häkli; Jivall, Lotti; Kempe, Christina; Kollo, Karin; Kosenko, Ksenija; Pihlak, Priit; Prizginiene, Dalia; Tangen, Oddvar; Weber, Mette; Paršeliūnas, Eimuntas; Baniulis, Rimvydas; Galinauskas, Karolis

2018-03-01

The Nordic Geodetic Commission (NKG) has launched a joint NKG GNSS Analysis Centre that aims to routinely produce high qualityGNSS solutions for the common needs of the NKG and the Nordic and Baltic countries. A consistent and densified velocity field is needed for the constraining of the gla-cial isostatic adjustment (GIA) modelling that is a key component of maintaining the national reference frame realisations in the area. We described the methods of the NKG GNSS Analysis Centre including the defined processing setup for the local analysis centres (LAC) and for the combination centres.We analysed the results of the first 2.5 years (2014.5-2016). The results showed that different subnets were consistent with the combined solution within 1-2 mm level. We observed the so called network effect affecting our reference frame alignment. However, the accuracy of the reference frame alignment was on a few millimetre level in the area of the main interest (Nordic and Baltic Countries). TheNKGGNSS AC was declared fully operational in April 2017.

Current Trends and Challenges in Satellite Laser Ranging

NASA Astrophysics Data System (ADS)

Appleby, Graham M.; Bianco, Giuseppe; Noll, Carey E.; Pavlis, Erricos C.; Pearlman, Michael R.

2016-12-01

Satellite Laser Ranging (SLR) is used to measure accurately the distance from ground stations to retro-reflectors on satellites and on the Moon. SLR is one of the fundamental space-geodetic techniques that define the International Terrestrial Reference Frame (ITRF), which is the basis upon which many aspects of global change over space, time, and evolving technology are measured; with VLBI the two techniques define the scale of the ITRF; alone the SLR technique defines its origin (geocenter). The importance of the reference frame has recently been recognized at the inter-governmental level through the United Nations, which adopted in February 2015 the Resolution "Global Geodetic Reference Frame for Sustainable Development." Laser Ranging provides precision orbit determination and instrument calibration and validation for satellite-borne altimeters for the better understanding of sea level change, ocean dynamics, ice mass-balance, and terrestrial topography. It is also a tool to study the dynamics of the Moon and fundamental constants and theories. With the exception of the currently in-orbit GPS constellation, all GNSS satellites now carry retro-reflectors for improved orbit determination, harmonization of reference frames, and in-orbit co-location and system performance validation; the next generation of GPS satellites due for launch from 2019 onwards will also carry retro-reflectors. The ILRS delivers weekly realizations that are accumulated sequentially to extend the ITRF and the Earth Orientation Parameter series with a daily resolution. SLR technology continues to evolve towards the next-generation laser ranging systems and it is expected to successfully meet the challenges of the GGOS2020 program for a future Global Space Geodetic Network. Ranging precision is improving as higher repetition rate, narrower pulse lasers, and faster detectors are implemented within the network. Automation and pass interleaving at some stations is expanding temporal coverage and greatly enhancing efficiency. Discussions are ongoing with some missions that will allow the SLR network stations to provide crucial, but energy-safe, range measurements to optically vulnerable satellites. New retro-reflector designs are improving the signal link and enable daylight ranging that is now the norm for many stations. We discuss many of these laser ranging activities and some of the tough challenges that the SLR network currently faces.

Deriving a geocentric reference frame for satellite positioning and navigation

NASA Technical Reports Server (NTRS)

Malla, R. P.; Wu, S.-C.

1988-01-01

With the advent of Earth-orbiting geodetic satellites, nongeocentric datums or reference frames have become things of the past. Accurate geocentric three-dimensional positioning is now possible and is of great importance for various geodetic and oceanographic applications. While relative positioning accuracy of a few centimeters has become a reality using very long baseline interferometry (VLBI), the uncertainty in the offset of the adopted coordinate system origin from the geocenter is still believed to be on the order of 1 meter. Satellite laser ranging (SLR), however, is capable of determining this offset to better than 10 cm, but this is possible only after years of measurements. Global Positioning System (GPS) measurements provide a powerful tool for an accurate determination of this origin offset. Two strategies are discussed. The first strategy utilizes the precise relative positions that were predetermined by VLBI to fix the frame orientation and the absolute scaling, while the offset from the geocenter is determined from GPS measurements. Three different cases are presented under this strategy. The reference frame thus adopted will be consistent with the VLBI coordinate system. The second strategy establishes a reference frame by holding only the longitude of one of the tracking sites fixed. The absolute scaling is determined by the adopted gravitational constant (GM) of the Earth; and the latitude is inferred from the time signature of the Earth rotation in the GPS measurements. The coordinate system thus defined will be a geocentric Earth-fixed coordinate system.

Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III.

NASA Astrophysics Data System (ADS)

Titov, O.; Pursimo, T.; Johnston, Helen M.; Stanford, Laura M.; Hunstead, Richard W.; Jauncey, David L.; Zenere, Katrina A.

2017-04-01

In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ˜160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.

Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Stanford, Laura M.; Pursimo, T.

In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ∼160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radiomore » sources.« less

A Newton-Euler Description for Sediment Movement.

NASA Astrophysics Data System (ADS)

Maniatis, G.; Hoey, T.; Drysdale, T.; Hodge, R. A.; Valyrakis, M.

2015-12-01

We present progress from the development of a purpose specific sensing system for sediment transport (Maniatis et al. 2013). This system utilises the capabilities of contemporary inertial micro-sensors (strap-down accelerometers and gyroscopes) to record fluvial transport from the moving body-frame of artificial pebbles modelled precisely to represent the motion of real, coarse sediment grains (D90=100 mm class). This type of measurements can be useful in the context of sediment transport only if the existing mathematical understanding of the process is updated. We test a new mathematical model which defines specifically how the data recorded in the body frame of the sensor (Lagrangian frame of reference) can be generalised to the reference frame of the flow (channel, Eulerian frame of reference). Given the association of the two most widely used models for sediment transport with those frames of reference (Shields' to Eulerian frame and HA. Einstein's to Lagrangian frame), this description builds the basis for the definition of explicit incipient motion criteria (Maniatis et al. 2015) and for the upscaling from point-grain scale measurements to averaged, cross-sectional, stream related metrics. Flume experiments where conducted in the Hydraulics laboratory of the University of Glasgow where a spherical sensor of 800 mm diameter and capable of recoding inertial dynamics at 80Hz frequency was tested under fluvial transport conditions. We managed to measure the dynamical response of the unit during pre-entrainment/entrainment transitions, on scaled and non-scaled to the sensor's diameter bed and for a range of hydrodynamic conditions (slope up to 0.02 and flow increase rate up to 0.05m3.s-1. Preliminary results from field deployment on a mixed bedrock-alluvial channel are also presented. Maniatis et. al 2013 J. Sens. Actuator Netw. 2013, 2(4), 761-779; Maniatis et. al 2015: "CALCULATION OF EXPLICIT PROBABILITY OF ENTRAINMENT BASED ON INERTIAL ACCELERATION MEASUREMENTS" J. Hydraulic Engineering, Under review.

Reference Frames and Relativity.

ERIC Educational Resources Information Center

Swartz, Clifford

1989-01-01

Stresses the importance of a reference frame in mechanics. Shows the Galilean transformation in terms of relativity theory. Discusses accelerated reference frames and noninertial reference frames. Provides examples of reference frames with diagrams. (YP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatia, Harsh

This dissertation presents research on addressing some of the contemporary challenges in the analysis of vector fields—an important type of scientific data useful for representing a multitude of physical phenomena, such as wind flow and ocean currents. In particular, new theories and computational frameworks to enable consistent feature extraction from vector fields are presented. One of the most fundamental challenges in the analysis of vector fields is that their features are defined with respect to reference frames. Unfortunately, there is no single “correct” reference frame for analysis, and an unsuitable frame may cause features of interest to remain undetected, thusmore » creating serious physical consequences. This work develops new reference frames that enable extraction of localized features that other techniques and frames fail to detect. As a result, these reference frames objectify the notion of “correctness” of features for certain goals by revealing the phenomena of importance from the underlying data. An important consequence of using these local frames is that the analysis of unsteady (time-varying) vector fields can be reduced to the analysis of sequences of steady (timeindependent) vector fields, which can be performed using simpler and scalable techniques that allow better data management by accessing the data on a per-time-step basis. Nevertheless, the state-of-the-art analysis of steady vector fields is not robust, as most techniques are numerical in nature. The residing numerical errors can violate consistency with the underlying theory by breaching important fundamental laws, which may lead to serious physical consequences. This dissertation considers consistency as the most fundamental characteristic of computational analysis that must always be preserved, and presents a new discrete theory that uses combinatorial representations and algorithms to provide consistency guarantees during vector field analysis along with the uncertainty visualization of unavoidable discretization errors. Together, the two main contributions of this dissertation address two important concerns regarding feature extraction from scientific data: correctness and precision. The work presented here also opens new avenues for further research by exploring more-general reference frames and more-sophisticated domain discretizations.« less

On the establishment and maintenance of a modern conventional terrestrial reference system

NASA Technical Reports Server (NTRS)

Bock, Y.; Zhu, S. Y.

1982-01-01

The frame of the Conventional Terrestrial Reference System (CTS) is defined by an adopted set of coordinates, at a fundamental epoxh, of a global network of stations which contribute the vertices of a fundamental polyhedron. A method to estimate this set of coordinates using a combination of modern three dimensional geodetic systems is presented. Once established, the function of the CTS is twofold. The first is to monitor the external (or global) motions of the polyhedron with respect to the frame of a Conventional Inertial Reference System, i.e., those motions common to all stations. The second is to monitor the internal motions (or deformations) of the polyhedron, i.e., those motions that are not common to all stations. Two possible estimators for use in earth deformation analysis are given and their statistical and physical properties are described.

Mixed Frames and Risky Decision-Making.

PubMed

Peng, Jiaxi; Zhang, Jiaxi; Sun, Hao; Zeng, Zhicong; Mai, Yuexia; Miao, Danmin

2017-01-01

By applying unitive vocabulary, "die" or "save," to respective frames of the Asian disease problem, Tversky and Kahneman were able to define framing effect. In this study, we preliminarily explored the effect of mixed frames, which are characterized by the use of different vocabulary in one frame. In study 1, we found that only the sure option description had significant effect on decision-making, while the effects of risky option descriptions were not significant, nor were interactions between descriptions. In study 2, the results suggested that after controlling the effects of the hedonic tone of the sure options, risky option description did not significantly predict decision-making. In study 3, we found that neither the sure-to-risky option presentation order nor presentation order within risky options had significant effect on decision-making. We thus concluded that sure option description can serve as the decision-making foundation (reference point) for decision-makers in mixed frames.

Fixing a Reference Frame to a Moving and Deforming Continent

NASA Astrophysics Data System (ADS)

Blewitt, G.; Kreemer, C.; Hammond, W. C.

2016-12-01

The U.S. National Spatial Reference System will be modernized in 2022. A foundational component will be a geocentric reference frame fixed to the North America tectonic plate. Here we address challenges of fixing a reference frame to a moving and deforming continent. Scientific applications motivate that we fix the frame with a scale consistent with the SI system, an origin that coincides with the Earth system's center of mass, and with axes attached to the rigidly rotating interior of the North America plate. Realizing the scale and origin is now achieved to < 0.5 mm/yr by combining space-geodetic techniques (SLR, VLBI, GPS, and DORIS) in the global system, ITRS. To realize the no-net rotation condition, the complexity of plate boundary deformation demands that we only select GPS stations far from plate boundaries. Another problem is that velocity uncertainties in models of glacial isostatic adjustment (GIA) are significant compared to uncertainties in observed velocities. GIA models generally agree that far-field horizontal velocities tend to be directed toward/away from Hudson Bay, depending on mantle viscosity, with uncertain sign and magnitude of velocity. Also in the far field, strain rates tend to be small beyond the peripheral bulge ( US-Canada border). Thus the Earth's crust in the US east of the Rockies may appear to be rigid, even if this region moves relative to plate motion. This can affect Euler vector estimation, with implications (pros and cons) on scientific interpretation. Our previous approach [ref. 1] in defining the NA12 frame was to select a core set of 30 stations east of the Rockies and south of the U.S.-Canada border that satisfy strict criteria on position time series quality. The resulting horizontal velocities have an RMS of 0.3 mm/yr, quantifying a combination of plate rigidity and accuracy. However, this does not rule out possible common-mode motion arising from GIA. For the development of new frame NA16, we consider approaches to this problem. We also apply new techniques including the MIDAS robust velocity estimator [ref. 2] and "GPS Imaging" of vertical motions and strain rates (Fig. 1), which together could assist in better defining "stable North America".[1] Blewitt et al. (2013). J. Geodyn. 72, 11-24, doi:10.1016/j.jog.2013.08.004[2] Blewitt et al. (2016). JGR 121, doi:10.1002/2015JB012552

a Simpler Solution of the Non-Uniqueness Problem of the Covariant Dirac Theory

NASA Astrophysics Data System (ADS)

Arminjon, Mayeul

2013-05-01

Although the standard generally covariant Dirac equation is unique in a topologically simple spacetime, it has been shown that it leads to non-uniqueness problems for the Hamiltonian and energy operators, including the non-uniqueness of the energy spectrum. These problems should be solved by restricting the choice of the Dirac gamma field in a consistent way. Recently, we proposed to impose the value of the rotation rate of the tetrad field. This is not necessarily easy to implement and works only in a given reference frame. Here, we propose that the gamma field should change only by constant gauge transformations. To get that situation, we are naturally led to assume that the metric can be put in a space-isotropic diagonal form. When this is the case, it distinguishes a preferred reference frame. We show that by defining the gamma field from the "diagonal tetrad" in a chart in which the metric has that form, the uniqueness problems are solved at once for all reference frames. We discuss the physical relevance of the metric considered and our restriction to first-quantized theory.

Interaction Between the Celestial and the Terrestrial Reference Frames

NASA Technical Reports Server (NTRS)

Gordon, David; MacMillan, Dan; Bolotin, Sergei; Le Bail, Karine; Gipson, John; Ma, Chopo

2010-01-01

Effects of International Celestial Reference Frame (ICRF2) on the Terrestrial Reference Frames (TRF), CRF and EOP's, The ICRF2 became official on Jan. 1, 2010. It includes positions of 3414 compact radio astronomical sources observed with VLBI, a fivefold increase from the first ICRF. Numerous new VLBI models were used and the most unstable sources were treated as arc parameters to avoid distortions of the frame. The ICRF2 has a noise floor of 40 micro-arc-seconds and an axis stability of 10 micro-arc-seconds. It was aligned with the ICRS using 138 stable sources common to ICRF2 and ICRF-Ext2. Maintenance of ICRF2 is to be made using 295 defining sources chosen for their historical positional stability, minimal source structure, and sky distribution. Their stability and their more uniform sky distribution eliminate the two largest weaknesses of ICRF I. The switchover to ICRF2 has some small effects on the TRF, CRF and Earth Orientation Parameters (EOP). A CRF based on ICRF2 shows a relative rotation of 40 micro-arc-seconds, mostly about the Y-axis. Small shifts are also seen in the EOP's, the largest being 11 micro-arc-seconds in X-pole. Some small but insignificant differences are also seen in the TRF. These results will be presented and discussed.

4D Dynamic Required Navigation Performance Final Report

NASA Technical Reports Server (NTRS)

Finkelsztein, Daniel M.; Sturdy, James L.; Alaverdi, Omeed; Hochwarth, Joachim K.

2011-01-01

New advanced four dimensional trajectory (4DT) procedures under consideration for the Next Generation Air Transportation System (NextGen) require an aircraft to precisely navigate relative to a moving reference such as another aircraft. Examples are Self-Separation for enroute operations and Interval Management for in-trail and merging operations. The current construct of Required Navigation Performance (RNP), defined for fixed-reference-frame navigation, is not sufficiently specified to be applicable to defining performance levels of such air-to-air procedures. An extension of RNP to air-to-air navigation would enable these advanced procedures to be implemented with a specified level of performance. The objective of this research effort was to propose new 4D Dynamic RNP constructs that account for the dynamic spatial and temporal nature of Interval Management and Self-Separation, develop mathematical models of the Dynamic RNP constructs, "Required Self-Separation Performance" and "Required Interval Management Performance," and to analyze the performance characteristics of these air-to-air procedures using the newly developed models. This final report summarizes the activities led by Raytheon, in collaboration with GE Aviation and SAIC, and presents the results from this research effort to expand the RNP concept to a dynamic 4D frame of reference.

Frame of Reference: Special Collections

ERIC Educational Resources Information Center

Goetsch, Lori A.

2010-01-01

Rare, distinctive, unique--academic libraries are exploring new ways to describe and define what they've traditionally called special collections: incunabula, manuscripts, rare books, cultural artifacts and more. These valuable, historically important, and often one-of-a-kind artifacts can be a treasure trove for scholars and students. Technology…

Physics in a Bouncing Car.

ERIC Educational Resources Information Center

Bartlett, Albert A.

1984-01-01

Defines frame of reference for the analysis of motion in a moving car, discussing the interaction of the car body, the seat springs, and the passenger when the car goes over a bump. Provides a related, but more advanced, problem with the motion of cars involving angular acceleration. (JM)

Transformative Relation of Kinematical Descriptive Quantities Defined by Different Spatial Referential Frame, Its Property and Application

NASA Astrophysics Data System (ADS)

Luo, Ji

2012-08-01

Quantitative transformations between corresponding kinetic quantities defined by any two spatial referential frames, whose relative kinematics relations (purely rotational and translational movement) are known, are presented based on necessarily descriptive definitions of the fundamental concepts (instant, time, spatial referential frame that distinguishes from Maths. Coordination, physical point) had being clarified by directly empirical observation with artificially descriptive purpose. Inductive investigation of the transformation reveals that all physical quantities such as charge, temperature, time, volume, length, temporal rate of the quantities and relations like temporal relation between signal source and observer as such are independent to spatial frames transformation except above kinematical quantities transformations, kinematics related dynamics such as Newton ’ s second law existing only in inertial frames and exchange of kinetic energy of mass being valid only in a selected inertial frame. From above bas is, we demonstrate a series of inferences and applications such as phase velocity of light being direct respect to medium (including vacuum) rather than to the frame, using spatial referential frame to describe any measurable field (electric field, magnetic field, gravitational field) and the field ’ s variation; and have tables to contrast and evaluate all aspects of those hypotheses related with spacetime such as distorted spacetime around massive stellar, four dimension spacetime, gravitational time dilation and non - Euclid geometry with new one. The demonstration strongly suggests all the hypotheses are invalid in capable tested concepts ’ meaning and relations. The conventional work on frame transformation and its property, hypothesized by Voigt, Heaviside, Lorentz, Poincare and Einstein a century ago with some mathematical speculation lacking rigorous definition of the fundamental concepts such as instant, time, spatial reference, straight line, plane area, merely good in building up patchwork to do self p referred explanation by making up derivative concepts or accumulating new hypothesis, has disturbed people to describe the physical nature by setting up the sound basis of concept and relations with capable tested method, it’s time to be replaced by empirically effective alternative.

Superconductor rotor cooling system

DOEpatents

Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.

2004-11-02

A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.

Superconductor rotor cooling system

DOEpatents

Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.

2002-01-01

A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.

Considering Time-Scale Requirements for the Future

DTIC Science & Technology

2013-05-01

geocentric reference frame with the SI second realized on the rotating geoid as the scale unit. It is a continuous atomic time scale that was...the B8lycentric and Geocentric Celestial Reference Systems, two time scales, Barycentric Coor- dinate Time (TCB) and Geocentric Coordinate Time (TCG...defined in 2006 as a linear scaling of TCB having the approximate rate of TT. TCG is the time coordinate for the four dimensional geocentric coordinate

Reference equations of motion for automatic rendezvous and capture

NASA Technical Reports Server (NTRS)

Henderson, David M.

1992-01-01

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

Datum maintenance of the main Egyptian geodetic control networks by utilizing Precise Point Positioning "PPP" technique

NASA Astrophysics Data System (ADS)

Rabah, Mostafa; Elmewafey, Mahmoud; Farahan, Magda H.

2016-06-01

A geodetic control network is the wire-frame or the skeleton on which continuous and consistent mapping, Geographic Information Systems (GIS), and surveys are based. Traditionally, geodetic control points are established as permanent physical monuments placed in the ground and precisely marked, located, and documented. With the development of satellite surveying methods and their availability and high degree of accuracy, a geodetic control network could be established by using GNSS and referred to an international terrestrial reference frame used as a three-dimensional geocentric reference system for a country. Based on this concept, in 1992, the Egypt Survey Authority (ESA) established two networks, namely High Accuracy Reference Network (HARN) and the National Agricultural Cadastral Network (NACN). To transfer the International Terrestrial Reference Frame to the HARN, the HARN was connected with four IGS stations. The processing results were 1:10,000,000 (Order A) for HARN and 1:1,000,000 (Order B) for NACN relative network accuracy standard between stations defined in ITRF1994 Epoch1996. Since 1996, ESA did not perform any updating or maintaining works for these networks. To see how non-performing maintenance degrading the values of the HARN and NACN, the available HARN and NACN stations in the Nile Delta were observed. The Processing of the tested part was done by CSRS-PPP Service based on utilizing Precise Point Positioning "PPP" and Trimble Business Center "TBC". The study shows the feasibility of Precise Point Positioning in updating the absolute positioning of the HARN network and its role in updating the reference frame (ITRF). The study also confirmed the necessity of the absent role of datum maintenance of Egypt networks.

Reynolds Stress Closure for Inertial Frames and Rotating Frames

NASA Astrophysics Data System (ADS)

Petty, Charles; Benard, Andre

2017-11-01

In a rotating frame-of-reference, the Coriolis acceleration and the mean vorticity field have a profound impact on the redistribution of kinetic energy among the three components of the fluctuating velocity. Consequently, the normalized Reynolds (NR) stress is not objective. Furthermore, because the Reynolds stress is defined as an ensemble average of a product of fluctuating velocity vector fields, its eigenvalues must be non-negative for all turbulent flows. These fundamental properties (realizability and non-objectivity) of the NR-stress cannot be compromised in computational fluid dynamic (CFD) simulations of turbulent flows in either inertial frames or in rotating frames. The recently developed universal realizable anisotropic prestress (URAPS) closure for the NR-stress depends explicitly on the local mean velocity gradient and the Coriolis operator. The URAPS-closure is a significant paradigm shift from turbulent closure models that assume that dyadic-valued operators associated with turbulent fluctuations are objective.

Geometric Cues, Reference Frames, and the Equivalence of Experienced-Aligned and Novel-Aligned Views in Human Spatial Memory

ERIC Educational Resources Information Center

Kelly, Jonathan W.; Sjolund, Lori A.; Sturz, Bradley R.

2013-01-01

Spatial memories are often organized around reference frames, and environmental shape provides a salient cue to reference frame selection. To date, however, the environmental cues responsible for influencing reference frame selection remain relatively unknown. To connect research on reference frame selection with that on orientation via…

The Connected Child: Tracing Digital Literacy from School to Leisure

ERIC Educational Resources Information Center

Bjørgen, Anne Mette; Erstad, Ola

2015-01-01

This article directs attention to how young students make sense of the connections and disconnections of digital practices between school and leisure. By using New Literacy Studies as a frame of reference, we study how students' conceptions of digital literacies and their positional identities are defined across school and home. In contrast to…

Soft Systems Methodology and Problem Framing: Development of an Environmental Problem Solving Model Respecting a New Emergent Reflexive Paradigm.

ERIC Educational Resources Information Center

Gauthier, Benoit; And Others

1997-01-01

Identifies the more representative problem-solving models in environmental education. Suggests the addition of a strategy for defining a problem situation using Soft Systems Methodology to environmental education activities explicitly designed for the development of critical thinking. Contains 45 references. (JRH)

China's Education Policy-Making: A Policy Network Perspective

ERIC Educational Resources Information Center

Han, Shuangmiao; Ye, Fugui

2017-01-01

Policy network approach has become a broadly accepted and frequently adopted practice in modern state governance, especially in the public sector. The study utilises a broadly defined policy network conceptual frame and categories of reference to trace the evolution of education policy-making in China. The study uses "The Outline of China's…

Vibration of a flexible spacecraft with momentum exchange controllers

NASA Technical Reports Server (NTRS)

Canavin, J. R.

1976-01-01

Floating reference frames were investigated in order to allow first order vibration analysis in the presence of large system rotations. When the deformations of an elastic continuum are expanded in terms of the free-free modes of an unconstrained system, the rigid body modes are found to be fixed relative to the Tisserand frame, with respect to which the relative momentum is zero. The proof presented for this is based on the orthogonality condition for modes with distinct natural frequencies. This result also guarantees the independence of coordinates for all modes with nonzero natural frequencies. A Modified Tisserand Constraint is introduced in order to define a floating reference frame with similar properties for an elastic body which contains a spinning rotor. Finite element equations of motion are derived for a completely flexible spacecraft with momentum exchange controllers, using a Modified Tisserand Frame. The deformable systems covered in this application are assumed to undergo only small rotations, and therefore the rotor torques must formally be small, although in engineering applications it may be possible to relax this constraint. A modal analysis is performed for the system and the resulting set of equations is reduced in number by a truncation procedure for more efficient system simulation.

Evolution of Timescales from Astronomy to Physical Metrology

DTIC Science & Technology

2011-07-20

2000 [7] recommended the use of the ‘non-rotating origin’ both in the Geocentric Celestial Reference System (GCRS) and the International Terrestrial...timescale defined in a geocentric reference frame with the SI second as realized on the rotating geoid as the scale unit’ [30, 31]. This meant that it was...of the new timescale for apparent geocentric ephemerides, will be 1977 January 1d.0003725 (1d 00h 00m 32.184s) exactly. (b) The unit of this timescale

Effect of Laterally Wedged Insoles on the External Knee Adduction Moment across Different Reference Frames.

PubMed

Yamaguchi, Satoshi; Kitamura, Masako; Ushikubo, Tomohiro; Murata, Atsushi; Akagi, Ryuichiro; Sasho, Takahisa

2015-01-01

Biomechanical effects of laterally wedged insoles are assessed by reduction in the knee adduction moment. However, the degree of reduction may vary depending on the reference frame with which it is calculated. The purpose of this study was to clarify the effect of reference frame on the reduction in the knee adduction moment by laterally wedged insoles. Twenty-nine healthy participants performed gait trials with a laterally wedged insole and with a flat insole as a control. The knee adduction moment, including the first and second peaks and the angular impulse, were calculated using four different reference frames: the femoral frame, tibial frame, laboratory frame and the Joint Coordinate System. There were significant effects of reference frame on the knee adduction moment first and second peaks (P < 0.001 for both variables), while the effect was not significant for the angular impulse (P = 0.84). No significant interaction between the gait condition and reference frame was found in either of the knee adduction moment variables (P = 0.99 for all variables), indicating that the effects of laterally wedged insole on the knee adduction moments were similar across the four reference frames. On the other hand, the average percent changes ranged from 9% to 16% for the first peak, from 16% to 18% for the second peak and from 17% to 21% for the angular impulse when using the different reference frames. The effects of laterally wedged insole on the reduction in the knee adduction moment were similar across the reference frames. On the other hand, Researchers need to recognize that when the percent change was used as the parameter of the efficacy of laterally wedged insole, the choice of reference frame may influence the interpretation of how laterally wedged insoles affect the knee adduction moment.

The reference frame for encoding and retention of motion depends on stimulus set size.

PubMed

Huynh, Duong; Tripathy, Srimant P; Bedell, Harold E; Öğmen, Haluk

2017-04-01

The goal of this study was to investigate the reference frames used in perceptual encoding and storage of visual motion information. In our experiments, observers viewed multiple moving objects and reported the direction of motion of a randomly selected item. Using a vector-decomposition technique, we computed performance during smooth pursuit with respect to a spatiotopic (nonretinotopic) and to a retinotopic component and compared them with performance during fixation, which served as the baseline. For the stimulus encoding stage, which precedes memory, we found that the reference frame depends on the stimulus set size. For a single moving target, the spatiotopic reference frame had the most significant contribution with some additional contribution from the retinotopic reference frame. When the number of items increased (Set Sizes 3 to 7), the spatiotopic reference frame was able to account for the performance. Finally, when the number of items became larger than 7, the distinction between reference frames vanished. We interpret this finding as a switch to a more abstract nonmetric encoding of motion direction. We found that the retinotopic reference frame was not used in memory. Taken together with other studies, our results suggest that, whereas a retinotopic reference frame may be employed for controlling eye movements, perception and memory use primarily nonretinotopic reference frames. Furthermore, the use of nonretinotopic reference frames appears to be capacity limited. In the case of complex stimuli, the visual system may use perceptual grouping in order to simplify the complexity of stimuli or resort to a nonmetric abstract coding of motion information.

How Flexible is the Use of Egocentric Versus Allocentric Frame of Reference in the Williams Syndrome Population?

PubMed

Heiz, J; Majerus, S; Barisnikov, K

2017-09-28

This study examined the spontaneous use of allocentric and egocentric frames of reference and their flexible use as a function of instructions. The computerized spatial reference task created by Heiz and Barisnikov (2015) was used. Participants had to choose a frame of reference according to three types of instructions: spontaneous, allocentric and egocentric. The performances of 16 Williams Syndrome participants between 10 and 41 years were compared to those of two control groups (chronological age and non-verbal intellectual ability). The majority of Williams Syndrome participants did not show a preference for a particular frame of reference. When explicitly inviting participants to use an allocentric frame of reference, all three groups showed an increased use of the allocentric frame of reference. At the same time, an important heterogeneity of type of frame of reference used by Williams Syndrome participants was observed. Results demonstrate that despite difficulties in the spontaneous use of allocentric and egocentric frames of reference, some Williams Syndrome participants show flexibility in the use of an allocentric frame of reference when an explicit instruction is provided. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Frames of Reference in the Classroom

ERIC Educational Resources Information Center

Grossman, Joshua

2012-01-01

The classic film "Frames of Reference" effectively illustrates concepts involved with inertial and non-inertial reference frames. In it, Donald G. Ivey and Patterson Hume use the cameras perspective to allow the viewer to see motion in reference frames translating with a constant velocity, translating while accelerating, and rotating--all with…

An Empirical Study of the Weigl-Goldstein-Scheerer Color-Form Test According to a Developmental Frame of Reference.

ERIC Educational Resources Information Center

Strauss, Helen; Lewin, Isaac

1982-01-01

Analyzed the Weigl-Goldstein-Scheerer Color-Form Test using a sample of Danish children. Distinguished three dimensions: configuration of sorting, verbalization of the sorting principle, and the flexibility of switching sorting principle. The three dimensions proved themselves to constitute the a-priori-defined gradients. Results indicated a…

Reframing as a Best Practice: The Priority of Process in Highly Adaptive Decision Making

ERIC Educational Resources Information Center

Peters, Gary B.

2008-01-01

The development and practice of a well-defined process in which decisions are fully contemplated is needed in education today. The complexity of societal issues requires new depths of understanding, appreciation, and communication. Framing refers to the way a situation is described or viewed; reframing is the process of expanding and enriching the…

From Winning-at-All-Costs to Give Us Back Our Game: Perspective Transformation in Youth Sport Coaches

ERIC Educational Resources Information Center

Fenoglio, Rick; Taylor, William

2014-01-01

Background: Drawing upon concepts from Mezirow's transformative learning theory, this research investigated the process of perspective transformation in three purposively sampled youth sport coaches in the UK. Perspective transformation is the process by which adults revise their culturally defined frames of reference which have arisen out of…

Pseudo-set framing.

PubMed

Barasz, Kate; John, Leslie K; Keenan, Elizabeth A; Norton, Michael I

2017-10-01

Pseudo-set framing-arbitrarily grouping items or tasks together as part of an apparent "set"-motivates people to reach perceived completion points. Pseudo-set framing changes gambling choices (Study 1), effort (Studies 2 and 3), giving behavior (Field Data and Study 4), and purchase decisions (Study 5). These effects persist in the absence of any reward, when a cost must be incurred, and after participants are explicitly informed of the arbitrariness of the set. Drawing on Gestalt psychology, we develop a conceptual account that predicts what will-and will not-act as a pseudo-set, and defines the psychological process through which these pseudo-sets affect behavior: over and above typical reference points, pseudo-set framing alters perceptions of (in)completeness, making intermediate progress seem less complete. In turn, these feelings of incompleteness motivate people to persist until the pseudo-set has been fulfilled. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Episodic payments (bundling): PART I.

PubMed

Jacofsky, D J

2017-10-01

Episodic, or bundled payments, is a concept now familiar to most in the healthcare arena, but the models are often misunderstood. Under a traditional fee-for-service model, each provider bills separately for their services which creates financial incentives to maximise volumes. Under a bundled payment, a single entity, often referred to as a convener (maybe the hospital, the physician group, or a third party) assumes the risk through a payer contract for all services provided within a defined episode of care, and receives a single (bundled) payment for all services provided for that episode. The time frame around the intervention is variable, but defined in advance, as are included and excluded costs. Timing of the actual payment in a bundle may either be before the episode occurs (prospective payment model), or after the end of the episode through a reconciliation (retrospective payment model). In either case, the defined costs over the defined time frame are borne by the convener. Cite this article: Bone Joint J 2017;99-B:1280-5. ©2017 The British Editorial Society of Bone & Joint Surgery.

Reframing Student Affairs Leadership: An Analysis of Organizational Frames of Reference and Locus of Control

ERIC Educational Resources Information Center

Tull, Ashley; Freeman, Jerrid P.

2011-01-01

Examined in this study were the identified frames of reference and locus of control used by 478 student affairs administrators. Administrator responses were examined to identify frames of reference most commonly used and their preference order. Locus of control most commonly used and the relationship between frames of reference and locus of…

Realization of ETRF2000 as a New Terrestrial Reference Frame in Republic of Serbia

NASA Astrophysics Data System (ADS)

Blagojevic, D.; Vasilic, V.

2012-12-01

The International Earth Rotation and Reference Systems Service (IERS) is a joint service of the International Association of Geodesy (IAG) and the International Astronomical Union (IAU), which provides the scientific community with the means for computing the transformation from the International Celestial Reference System (ICRS) to the International Terrestrial Reference System (ITRS). It further maintains the realizations of these systems by appropriate coordinate sets called "frames". The densification of terrestrial frame usually serves as official frame for positioning and navigation tasks within the territory of particular country. One of these densifications was recently performed in order to establish new reference frame for Republic of Serbia. The paper describes related activities resulting in ETRF2000 as a new Serbian terrestrial reference frame.

A soil sampling reference site: the challenge in defining reference material for sampling.

PubMed

de Zorzi, Paolo; Barbizzi, Sabrina; Belli, Maria; Fajgelj, Ales; Jacimovic, Radojko; Jeran, Zvonka; Sansone, Umberto; van der Perk, Marcel

2008-11-01

In the frame of the international SOILSAMP project, funded and coordinated by the Italian Environmental Protection Agency, an agricultural area was established as a reference site suitable for performing soil sampling inter-comparison exercises. The reference site was characterized for trace element content in soil, in terms of the spatial and temporal variability of their mass fraction. Considering that the behaviour of long-lived radionuclides in soil can be expected to be similar to that of some stable trace elements and that the distribution of these trace elements in soil can simulate the distribution of radionuclides, the reference site characterised in term of trace elements, can be also used to compare the soil sampling strategies developed for radionuclide investigations.

Embodied Interaction Priority: Other's Body Part Affects Numeral-Space Mappings.

PubMed

You, Xuqun; Zhang, Yu; Zhu, Rongjuan; Guo, Yu

2018-01-01

Traditionally, the spatial-numerical association of response codes (SNARC) effect was presented in two-choice condition, in which only one individual reacted to both even (small) and odd (large) numbers. Few studies explored SNARC effect in a social situation. Moreover, there are many reference frames involved in SNARC effect, and it has not yet been investigated which reference frame is dominated when two participants perform the go-nogo task together. In the present study, we investigated which reference frame plays a primary role in SNARC effect when allocentric and egocentric reference frames were consistent or inconsistent in social settings. Furthermore, we explored how two actors corepresent number-space mapping interactively. Results of the two experiments demonstrated that egocentric reference frame was at work primarily when two reference frames were consistent and inconsistent. This shows that body-centered coordinate frames influence number-space mapping in social settings, and one actor may represent another actor's action and tasks.

Mission Capability Gains from Multi-Mode Propulsion Thrust Variations on a Variety Spacecraft Orbital Maneuvers

DTIC Science & Technology

2011-03-01

Geocentric -Equatorial Reference Frame2 ....................................................................... 31  Figure 8: Perifocal and Geocentric ...67  Figure 25: Mission 3 Geocentric Equatorial Reference Frame ...................................................... 69  Figure 26: Mission 3...Coordinate system, the Geocentric -Equatorial Reference frame and the reference frame depicted on one another is shown below. The following figures are from

Global and regional kinematics with GPS

NASA Technical Reports Server (NTRS)

King, Robert W.

1994-01-01

The inherent precision of the doubly differenced phase measurement and the low cost of instrumentation made GPS the space geodetic technique of choice for regional surveys as soon as the constellation reached acceptable geometry in the area of interest: 1985 in western North America, the early 1990's in most of the world. Instrument and site-related errors for horizontal positioning are usually less than 3 mm, so that the dominant source of error is uncertainty in the reference frame defined by the satellites orbits and the tracking stations used to determine them. Prior to about 1992, when the tracking network for most experiments was globally sparse, the number of fiducial sites or the level at which they could be tied to an SLR or VLBI reference frame usually, set the accuracy limit. Recently, with a global network of over 30 stations, the limit is set more often by deficiencies in models for non-gravitational forces acting on the satellites. For regional networks in the northern hemisphere, reference frame errors are currently about 3 parts per billion (ppb) in horizontal position, allowing centimeter-level accuracies over intercontinental distances and less than 1 mm for a 100 km baseline. The accuracy of GPS measurements for monitoring height variations is generally 2-3 times worse than for horizontal motions. As for VLBI, the primary source of error is unmodeled fluctuations in atmospheric water vapor, but both reference frame uncertainties and some instrument errors are more serious for vertical than horizontal measurements. Under good conditions, daily repeatabilities at the level of 10 mm rms were achieved. This paper will summarize the current accuracy of GPS measurements and their implication for the use of SLR to study regional kinematics.

Analysis of the Climate Change Technology Initiative

EIA Publications

1999-01-01

Analysis of the impact of specific policies on the reduction of carbon emissions and their impact on U.S. energy use and prices in the 2008-2012 time frame. Also, analyzes the impact of the President's Climate Change Technology Initiative, as defined for the 2000 budget, on reducing carbon emissions from the levels forecast in the Annual Energy Outlook 1999 reference case.

Native American Perspectives on Educational Experiences from within the Not So Ivory Tower

ERIC Educational Resources Information Center

Holmes, Frances Kay

2013-01-01

This dissertation explores how education has had an impact on the lives of twenty-three professors who are Native. Within the context of this study, education may refer to either learning in the western frame of schooling or non western forms of Indigenous education. While many individuals would define education as a process that develops life and…

Kalman Filter for Spinning Spacecraft Attitude Estimation

NASA Technical Reports Server (NTRS)

Markley, F. Landis; Sedlak, Joseph E.

2008-01-01

This paper presents a Kalman filter using a seven-component attitude state vector comprising the angular momentum components in an inertial reference frame, the angular momentum components in the body frame, and a rotation angle. The relatively slow variation of these parameters makes this parameterization advantageous for spinning spacecraft attitude estimation. The filter accounts for the constraint that the magnitude of the angular momentum vector is the same in the inertial and body frames by employing a reduced six-component error state. Four variants of the filter, defined by different choices for the reduced error state, are tested against a quaternion-based filter using simulated data for the THEMIS mission. Three of these variants choose three of the components of the error state to be the infinitesimal attitude error angles, facilitating the computation of measurement sensitivity matrices and causing the usual 3x3 attitude covariance matrix to be a submatrix of the 6x6 covariance of the error state. These variants differ in their choice for the other three components of the error state. The variant employing the infinitesimal attitude error angles and the angular momentum components in an inertial reference frame as the error state shows the best combination of robustness and efficiency in the simulations. Attitude estimation results using THEMIS flight data are also presented.

InSAR datum connection using GNSS-augmented radar transponders

NASA Astrophysics Data System (ADS)

Mahapatra, Pooja; der Marel, Hans van; van Leijen, Freek; Samiei-Esfahany, Sami; Klees, Roland; Hanssen, Ramon

2018-01-01

Deformation estimates from Interferometric Synthetic Aperture Radar (InSAR) are relative: they form a `free' network referred to an arbitrary datum, e.g. by assuming a reference point in the image to be stable. However, some applications require `absolute' InSAR estimates, i.e. expressed in a well-defined terrestrial reference frame, e.g. to compare InSAR results with those of other techniques. We propose a methodology based on collocated InSAR and Global Navigation Satellite System (GNSS) measurements, achieved by rigidly attaching phase-stable millimetre-precision compact active radar transponders to GNSS antennas. We demonstrate this concept through a simulated example and practical case studies in the Netherlands.

Environmental Inversion Effects in Face Perception

ERIC Educational Resources Information Center

Davidenko, Nicolas; Flusberg, Stephen J.

2012-01-01

Visual processing is highly sensitive to stimulus orientation; for example, face perception is drastically worse when faces are oriented inverted vs. upright. However, stimulus orientation must be established in relation to a particular reference frame, and in most studies, several reference frames are conflated. Which reference frame(s) matter in…

VizieR Online Data Catalog: VLBI ICRF2 (Fey+, 2015)

NASA Astrophysics Data System (ADS)

Fey, A. L.; Gordon, D.; Jacobs, C. S.; Ma, C.; Gaume, R. A.; Arias, E. F.; Bianco, G.; Boboltz, D. A.; Bockmann, S.; Bolotin, S.; Charlot, P.; Collioud, A.; Engelhardt, G.; Gipson, J.; Gontier, A.-M.; Heinkelmann, R.; Kurdubov, S.; Lambert, S.; Lytvyn, S.; MacMillan, D. S.; Malkin, Z.; Nothnagel, A.; Ojha, R.; Skurikhina, E.; Sokolova, J.; Souchay, J.; Sovers, O. J.; Tesmer, V.; Titov, O.; Wang, G.; Zharov, V.

2016-01-01

We present the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry observations. The earliest observations used are from 1979 August and the latest are from 2009 March. ICRF2 consists of accurate positions of 295 new "defining" sources and positions of 3119 additional compact radio sources to densify the frame. ICRF2 has more than 5 times as many sources as ICRF1 (Ma et al. 1997, cat. I/251), is roughly 5-6 times more accurate, and is nearly twice as stable in the orientation of its axes. (3 data files).

Classical and quantum communication without a shared reference frame.

PubMed

Bartlett, Stephen D; Rudolph, Terry; Spekkens, Robert W

2003-07-11

We show that communication without a shared reference frame is possible using entangled states. Both classical and quantum information can be communicated with perfect fidelity without a shared reference frame at a rate that asymptotically approaches one classical bit or one encoded qubit per transmitted qubit. We present an optical scheme to communicate classical bits without a shared reference frame using entangled photon pairs and linear optical Bell state measurements.

Frames of Reference: A Metaphor for Analyzing and Interpreting Attitudes of Environmental Policy Makers and Policy Influencers

PubMed

Swaffield

1998-07-01

/ The concept of frame of reference offers a potentially useful analytical metaphor in environmental management. This is illustrated by a case study in which attitudes of individuals involved in the management of trees in the New Zealand high country are classified into seven distinctive frames of reference. Some practical and theoretical implications of the use of the frame metaphor are explored, including its potential contribution to the emerg- ing field of communicative planning. KEY WORDS: Frames of reference; Environmental policy analysis; Metaphor; New Zealand high country

The Global Geodetic Observing System: Space Geodesy Networks for the Future

NASA Technical Reports Server (NTRS)

Pearlman, Michael; Pavlis, Erricos; Ma, Chopo; Altamini, Zuheir; Noll, Carey; Stowers, David

2011-01-01

Ground-based networks of co-located space geodetic techniques (VLBI, SLR, GNSS. and DORIS) are the basis for the development and maintenance of the International Terrestrial Reference frame (ITRF), which is our metric of reference for measurements of global change, The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) has established a task to develop a strategy to design, integrate and maintain the fundamental geodetic network and supporting infrastructure in a sustainable way to satisfy the long-term requirements for the reference frame. The GGOS goal is an origin definition at 1 mm or better and a temporal stability on the order of 0.1 mm/y, with similar numbers for the scale and orientation components. These goals are based on scientific requirements to address sea level rise with confidence, but other applications are not far behind. Recent studies including one by the US National Research Council has strongly stated the need and the urgency for the fundamental space geodesy network. Simulations are underway to examining accuracies for origin, scale and orientation of the resulting ITRF based on various network designs and system performance to determine the optimal global network to achieve this goal. To date these simulations indicate that 24 - 32 co-located stations are adequate to define the reference frame and a more dense GNSS and DORIS network will be required to distribute the reference frame to users anywhere on Earth. Stations in the new global network will require geologically stable sites with good weather, established infrastructure, and local support and personnel. GGOS wil seek groups that are interested in participation. GGOS intends to issues a Call for Participation of groups that would like to contribute in the network implementation and operation. Some examples of integrated stations currently in operation or under development will be presented. We will examine necessary conditions and challenges in designing a co-location station.

GNSS RTK-networks: The significance and issues to realize a recent reference coordinate system

NASA Astrophysics Data System (ADS)

Umnig, Elke; Möller, Gregor; Weber, Robert

2014-05-01

The upcoming release of the new global reference frame ITRF2013 will provide high accurate reference station positions and station velocities at the mm- and mm/year level, respectively. ITRF users benefit from this development in various ways. For example, this new frame allows for embedding high accurate GNSS baseline observations to an underlying reference of at least the same accuracy. Another advantage is that the IGS products are fully consistent with this frame and therefore all GNSS based zero-difference positioning results (Precise Point Positioning (PPP)) will be aligned to the ITRF2013. Unfortunately the transistion to a new frame (or just to a new epoch) implies also issues in particular for providers and users of real time positioning services. Thus providers have to perform arrangements, such as the readjustment of the reference station coordinates and the update of the transformation parameters from the homogenous GNSS coordinate frame into the national datum. Finally providers have to inform their clients appropriately about these changes and significant adjustments. Furthermore the aspect of the continental reference frame has to be considered: In Europe the use of the continental reference system/reference frame ETRS89/ETRF2000 is, due to cross-national guidelines, recommend by most national mapping authorities. Subsequently GNSS post-processing applications are degraded by the concurrent use of the reference systems and reference frames, to which terrestrial site coordinates and satellite coordinates are aligned. In this presentation we highlight all significant steps and hurdles which have to be jumped over when introducing a new reference frame from point of view of a typical regional RTK-reference station network provider. This network is located in Austria and parts of the neighbouring countries and consists of about 40 reference stations. Moreover, we discuss the significance of permanently monitoring the stability of the reference network sites and the determination of station velocities/rates for geodynamical investigations.

Connection Between the ICRF and the Dynamical Reference Frame for the Outer Planets

NASA Astrophysics Data System (ADS)

da Silva Neto, D. N.; Assafin, M.; Andrei, A. H.; Vieira Martins, R.

2005-01-01

This work brings an approach intending to improve the connection between the Dynamical Reference Frame and the Extragalactic Reference Frame. For that, close encounters of outer Solar System objects and quasars are used. With this goal, Uranus, Neptune and two quasars were observed at Laborat´orio Nacional de Astrof´ısica (LNA), Brazil. The optical reference frame is the HCRF, as given by the UCAC2 catalogue. The first results show an accuracy of 45 mas - 50 mas in the optical positions. The optical minus radio offsets give the local orientation between the catalogue and radio frame. From this, it is possible to place the optical planet coordinates on the extragalactic frame. A comparison between the new corrected optical coordinates and the respective DE ephemeris to these planets can give the instant orientations of the Dynamical Reference Frame with regard to the ICRS, for this zone of outer Solar System.

Estimating pixel variances in the scenes of staring sensors

DOEpatents

Simonson, Katherine M [Cedar Crest, NM; Ma, Tian J [Albuquerque, NM

2012-01-24

A technique for detecting changes in a scene perceived by a staring sensor is disclosed. The technique includes acquiring a reference image frame and a current image frame of a scene with the staring sensor. A raw difference frame is generated based upon differences between the reference image frame and the current image frame. Pixel error estimates are generated for each pixel in the raw difference frame based at least in part upon spatial error estimates related to spatial intensity gradients in the scene. The pixel error estimates are used to mitigate effects of camera jitter in the scene between the current image frame and the reference image frame.

Balance of Risk in the South China Sea

DTIC Science & Technology

2015-06-01

administrative control.156 In February 2009, the Philippine legislature passed an archipelagic baseline law that legally defined their domestic claims to...hard power, military doctrine , strategy, and tactics that are aligned with framing a favorable reference point of the territory inside of the nine...reinterpretation of Chinese foreign policy, and changes to military doctrine . The variations are evident in lower echelons of the state by changes to

Contextual cueing of tactile search is coded in an anatomical reference frame.

PubMed

Assumpção, Leonardo; Shi, Zhuanghua; Zang, Xuelian; Müller, Hermann J; Geyer, Thomas

2018-04-01

This work investigates the reference frame(s) underlying tactile context memory, a form of statistical learning in a tactile (finger) search task. In this task, if a searched-for target object is repeatedly encountered within a stable spatial arrangement of task-irrelevant distractors, detecting the target becomes more efficient over time (relative to nonrepeated arrangements), as learned target-distractor spatial associations come to guide tactile search, thus cueing attention to the target location. Since tactile search displays can be represented in several reference frames, including multiple external and an anatomical frame, in Experiment 1 we asked whether repeated search displays are represented in tactile memory with reference to an environment-centered or anatomical reference frame. In Experiment 2, we went on examining a hand-centered versus anatomical reference frame of tactile context memory. Observers performed a tactile search task, divided into a learning and test session. At the transition between the two sessions, we introduced postural manipulations of the hands (crossed ↔ uncrossed in Expt. 1; palm-up ↔ palm-down in Expt. 2) to determine the reference frame of tactile contextual cueing. In both experiments, target-distractor associations acquired during learning transferred to the test session when the placement of the target and distractors was held constant in anatomical, but not external, coordinates. In the latter, RTs were even slower for repeated displays. We conclude that tactile contextual learning is coded in an anatomical reference frame. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Instrument Pointing Capabilities: Past, Present, and Future

NASA Technical Reports Server (NTRS)

Blackmore, Lars; Murray, Emmanuell; Scharf, Daniel P.; Aung, Mimi; Bayard, David; Brugarolas, Paul; Hadaegh, Fred; Lee, Allan; Milman, Mark; Sirlin, Sam;

Accurate Realization of GPS Vertical Global Reference Frame

NASA Technical Reports Server (NTRS)

Elosegui, Pedro

2005-01-01

The goal of this project is to improve our current understanding of GPS error sources associated with estimates of radial velocities at global scales. An improvement in the accuracy of radial global velocities would have a very positive impact on a large number of geophysical studies of current general interest such as global sea-level and climate change, coastal hazards, glacial isostatic adjustment, atmospheric and oceanic loading, glaciology and ice mass variability, tectonic deformation and volcanic inflation, and geoid variability. A set of GPS error sources relevant to this project are those related to the combination of the positions and velocities of a set of globally distributed stations as determined &om the analysis of GPS data, including possible methods of combining and defining terrestrial reference frames. This is were our research activities during this reporting period have concentrated. During this reporting period, we have researched two topics: (1) The effect of errors on the GPS satellite antenna models (or lack thereof) on global GPS vertical position and velocity estimates; (2) The effect of reference W e definition and practice on estimates of the geocenter variations.

Modes of asymmetry: The application of harmonic analysis to symmetric quantum dynamics and quantum reference frames

NASA Astrophysics Data System (ADS)

Marvian, Iman; Spekkens, Robert W.

2014-12-01

Finding the consequences of symmetry for open-system quantum dynamics is a problem with broad applications, including describing thermal relaxation, deriving quantum limits on the performance of amplifiers, and exploring quantum metrology in the presence of noise. The symmetry of the dynamics may reflect a symmetry of the fundamental laws of nature or a symmetry of a low-energy effective theory, or it may describe a practical restriction such as the lack of a reference frame. In this paper, we apply some tools of harmonic analysis together with ideas from quantum information theory to this problem. The central idea is to study the decomposition of quantum operations—in particular, states, measurements, and channels—into different modes, which we call modes of asymmetry. Under symmetric processing, a given mode of the input is mapped to the corresponding mode of the output, implying that one can only generate a given output if the input contains all of the necessary modes. By defining monotones that quantify the asymmetry in a particular mode, we also derive quantitative constraints on the resources of asymmetry that are required to simulate a given asymmetric operation. We present applications of our results for deriving bounds on the probability of success in nondeterministic state transitions, such as quantum amplification, and a simplified formalism for studying the degradation of quantum reference frames.

Building and using a statistical 3D motion atlas for analyzing myocardial contraction in MRI

NASA Astrophysics Data System (ADS)

Rougon, Nicolas F.; Petitjean, Caroline; Preteux, Francoise J.

2004-05-01

We address the issue of modeling and quantifying myocardial contraction from 4D MR sequences, and present an unsupervised approach for building and using a statistical 3D motion atlas for the normal heart. This approach relies on a state-of-the-art variational non rigid registration (NRR) technique using generalized information measures, which allows for robust intra-subject motion estimation and inter-subject anatomical alignment. The atlas is built from a collection of jointly acquired tagged and cine MR exams in short- and long-axis views. Subject-specific non parametric motion estimates are first obtained by incremental NRR of tagged images onto the end-diastolic (ED) frame. Individual motion data are then transformed into the coordinate system of a reference subject using subject-to-reference mappings derived by NRR of cine ED images. Finally, principal component analysis of aligned motion data is performed for each cardiac phase, yielding a mean model and a set of eigenfields encoding kinematic ariability. The latter define an organ-dedicated hierarchical motion basis which enables parametric motion measurement from arbitrary tagged MR exams. To this end, the atlas is transformed into subject coordinates by reference-to-subject NRR of ED cine frames. Atlas-based motion estimation is then achieved by parametric NRR of tagged images onto the ED frame, yielding a compact description of myocardial contraction during diastole.

4D Dynamic RNP Annual Interim Report-Year 1

NASA Technical Reports Server (NTRS)

Finkelsztein, Daniel M.; Sturdy, James L.; Alaverdi, Omeed; Chung, William W.; Salvano, Daniel; Klooster, Joel; Hochwarth, Joachim K.

2010-01-01

This Annual Interim Report summarizes the activities led by Raytheon, in collaboration with GE Aviation and SAIC, and presents the results obtained during the first year of this research effort to expand the RNP concept to 4 dimensions relative to a dynamic frame of reference. Joint Program Development Office (JPDO)Concepts of Operations for the Next Generation Air Transportation System (NextGen) considers 4 Dimension Trajectory (4DT) procedures a key enabler to Trajectory Based Operations (TBO). The JPDO defines 4DT as a precise description of an aircraft path in space and time . While NextGen assumes that this path is defined within an Earth-reference frame, many 4DT procedure implementations will require an aircraft to precisely navigate relative to a moving reference such as another aircraft to form aggregate flows or a weather cell to allow for flows to shift. Current methods of implementing routes and flight paths rely on aircraft meeting a Required Navigation Performance (RNP) specification and being equipped with a monitoring and alerting capability to annunciate when the aircraft system is unable to meet the performance specification required for the operation. Since all aircraft today operate within the NAS relative to fixed reference points, the current RNP definition is deemed satisfactory. However, it is not well understood how the current RNP construct will support NextGen 4DT procedures where aircraft operate relative to each other or to other dynamic frames of reference. The objective of this research effort is to analyze candidate 4DT procedures from both an Air Navigation Service Provider (ANSP) and aircraft perspective, to identify their specific navigational requirements, assess the shortcomings of the current RNP construct to meet these requirements, to propose an extended 4 Dimensional Dynamic RNP (4D Dynamic RNP) construct that accounts for the dynamic spatial and temporal nature of the selected 4DT procedures, and finally, to design an experiment using the Airspace and Traffic Operations Simulation (ATOS) system to validate the 4D Dynamic RNP construct. This Annual Interim Report summarizes the activities led by Raytheon, in collaboration with GE Aviation and SAIC, and presents the results obtained during the first year of this research effort to expand the RNP concept to 4 dimensions relative to a dynamic frame of reference. A comprehensive assessment of the state-of-the-art international implementation of current RNP was completed and presented in the Contractor Report RNP State-of-the-Art Assessment, Version 4, 17 December 2008 . The team defined in detail two 4DT operations, Airborne Precision Spacing and Self-Separation, that are ideally suited to be supported by 4D Dynamic RNP and developed their respective conceptual frameworks, Required Interval Management Performance (RIMP) Version 1.1, 13 April 2009 and Required Self Separation Performance (RSSP) Version 1.1, 13 April 2009 . Finally, the team started the development of a mathematical model and simulation tool for RIMP and RSSP scheduled to be delivered during the second year of this research effort.

A Direct Georeferencing Method for Terrestrial Laser Scanning Using GNSS Data and the Vertical Deflection from Global Earth Gravity Models

PubMed Central

Borkowski, Andrzej; Owczarek-Wesołowska, Magdalena; Gromczak, Anna

2017-01-01

Terrestrial laser scanning is an efficient technique in providing highly accurate point clouds for various geoscience applications. The point clouds have to be transformed to a well-defined reference frame, such as the global Geodetic Reference System 1980. The transformation to the geocentric coordinate frame is based on estimating seven Helmert parameters using several GNSS (Global Navigation Satellite System) referencing points. This paper proposes a method for direct point cloud georeferencing that provides coordinates in the geocentric frame. The proposed method employs the vertical deflection from an external global Earth gravity model and thus demands a minimum number of GNSS measurements. The proposed method can be helpful when the number of georeferencing GNSS points is limited, for instance in city corridors. It needs only two georeferencing points. The validation of the method in a field test reveals that the differences between the classical georefencing and the proposed method amount at maximum to 7 mm with the standard deviation of 8 mm for all of three coordinate components. The proposed method may serve as an alternative for the laser scanning data georeferencing, especially when the number of GNSS points is insufficient for classical methods. PMID:28672795

A Direct Georeferencing Method for Terrestrial Laser Scanning Using GNSS Data and the Vertical Deflection from Global Earth Gravity Models.

PubMed

Osada, Edward; Sośnica, Krzysztof; Borkowski, Andrzej; Owczarek-Wesołowska, Magdalena; Gromczak, Anna

2017-06-24

Terrestrial laser scanning is an efficient technique in providing highly accurate point clouds for various geoscience applications. The point clouds have to be transformed to a well-defined reference frame, such as the global Geodetic Reference System 1980. The transformation to the geocentric coordinate frame is based on estimating seven Helmert parameters using several GNSS (Global Navigation Satellite System) referencing points. This paper proposes a method for direct point cloud georeferencing that provides coordinates in the geocentric frame. The proposed method employs the vertical deflection from an external global Earth gravity model and thus demands a minimum number of GNSS measurements. The proposed method can be helpful when the number of georeferencing GNSS points is limited, for instance in city corridors. It needs only two georeferencing points. The validation of the method in a field test reveals that the differences between the classical georefencing and the proposed method amount at maximum to 7 mm with the standard deviation of 8 mm for all of three coordinate components. The proposed method may serve as an alternative for the laser scanning data georeferencing, especially when the number of GNSS points is insufficient for classical methods.

Gravity matters: Motion perceptions modified by direction and body position.

PubMed

Claassen, Jens; Bardins, Stanislavs; Spiegel, Rainer; Strupp, Michael; Kalla, Roger

2016-07-01

Motion coherence thresholds are consistently higher at lower velocities. In this study we analysed the influence of the position and direction of moving objects on their perception and thereby the influence of gravity. This paradigm allows a differentiation to be made between coherent and randomly moving objects in an upright and a reclining position with a horizontal or vertical axis of motion. 18 young healthy participants were examined in this coherent threshold paradigm. Motion coherence thresholds were significantly lower when position and motion were congruent with gravity independent of motion velocity (p=0.024). In the other conditions higher motion coherence thresholds (MCT) were found at lower velocities and vice versa (p<0.001). This result confirms previous studies with higher MCT at lower velocity but is in contrast to studies concerning perception of virtual turns and optokinetic nystagmus, in which differences of perception were due to different directions irrespective of body position, i.e. perception took place in an egocentric reference frame. Since the observed differences occurred in an upright position only, perception of coherent motion in this study is defined by an earth-centered reference frame rather than by an ego-centric frame. Copyright © 2016 Elsevier Inc. All rights reserved.

The role of perspective taking in how children connect reference frames when explaining astronomical phenomena

NASA Astrophysics Data System (ADS)

Plummer, Julia D.; Bower, Corinne A.; Liben, Lynn S.

2016-02-01

This study investigates the role of perspective-taking skills in how children explain spatially complex astronomical phenomena. Explaining many astronomical phenomena, especially those studied in elementary and middle school, requires shifting between an Earth-based description of the phenomena and a space-based reference frame. We studied 7- to 9-year-old children (N = 15) to (a) develop a method for capturing how children make connections between reference frames and to (b) explore connections between perspective-taking skill and the nature of children's explanations. Children's explanations for the apparent motion of the Sun and stars and for seasonal changes in constellations were coded for accuracy of explanation, connection between frames of reference, and use of gesture. Children with higher spatial perspective-taking skills made more explicit connections between reference frames and used certain gesture-types more frequently, although this pattern was evident for only some phenomena. Findings suggest that children - particularly those with lower perspective-taking skills - may need additional support in learning to explicitly connect reference frames in astronomy. Understanding spatial thinking among children who successfully made explicit connections between reference frames in their explanations could be a starting point for future instruction in this domain.

Four-Year-Olds Use a Mixture of Spatial Reference Frames

PubMed Central

Negen, James; Nardini, Marko

2015-01-01

Keeping track of unseen objects is an important spatial skill. In order to do this, people must situate the object in terms of different frames of reference, including body position (egocentric frame of reference), landmarks in the surrounding environment (extrinsic frame reference), or other attached features (intrinsic frame of reference). Nardini et al. hid a toy in one of 12 cups in front of children, turned the array when they were not looking, and then asked them to point to the cup with the toy. This forced children to use the intrinsic frame (information about the array of cups) to locate the hidden toy. Three-year-olds made systematic errors by using the wrong frame of reference, 4-year-olds were at chance, and only 5- and 6-year-olds were successful. Can we better understand the developmental change that takes place at four years? This paper uses a modelling approach to re-examine the data and distinguish three possible strategies that could lead to the previous results at four years: (1) Children were choosing cups randomly, (2) Children were pointing between the egocentric/extrinsic-cued location and the correct target, and (3) Children were pointing near the egocentric/extrinsic-cued location on some trials and near the target on the rest. Results heavily favor the last possibility: 4-year-olds were not just guessing or trying to combine the available frames of reference. They were using the intrinsic frame on some trials, but not doing so consistently. These insights suggest that accounts of improving spatial performance at 4 years need to explain why there is a mixture of responses. Further application of the selected model also suggests that children become both more reliant on the correct frame and more accurate with any chosen frame as they mature. PMID:26133990

Spatial cognition and navigation

NASA Technical Reports Server (NTRS)

Aretz, Anthony J.

1989-01-01

An experiment that provides data for the development of a cognitive model of pilot flight navigation is described. The experiment characterizes navigational awareness as the mental alignment of two frames of reference: (1) the ego centered reference frame that is established by the forward view out of the cockpit and (2) the world centered reference frame that is established by the aircraft's location on a map. The data support a model involving at least two components: (1) the perceptual encoding of the navigational landmarks and (2) the mental rotation of the map's world reference frame into alignment with the ego centered reference frame. The quantitative relationships of these two factors are provided as possible inputs for a computational model of spatial cognition during flight navigation.

The effects of feedback format, and egocentric & allocentric relative phase on coordination stability.

PubMed

Pickavance, John; Azmoodeh, Arianne; Wilson, Andrew D

2018-06-01

The stability of coordinated rhythmic movement is primarily affected by the required mean relative phase. In general, symmetrical coordination is more stable than asymmetrical coordination; however, there are two ways to define relative phase and the associated symmetries. The first is in an egocentric frame of reference, with symmetry defined relative to the sagittal plane down the midline of the body. The second is in an allocentric frame of reference, with symmetry defined in terms of the relative direction of motion. Experiments designed to separate these constraints have shown that both egocentric and allocentric constraints contribute to overall coordination stability, with the former typically showing larger effects. However, separating these constraints has meant comparing movements made either in different planes of motion, or by limbs in different postures. In addition, allocentric information about the coordination is either in the form of the actual limb motion, or a transformed, Lissajous feedback display. These factors limit both the comparisons that can be made and the interpretations of these comparisons. The current study examined the effects of egocentric relative phase, allocentric relative phase, and allocentric feedback format on coordination stability in a single task. We found that while all three independently contributed to stability, the egocentric constraint dominated. This supports previous work. We examine the evidence underpinning theoretical explanations for the egocentric constraint, and describe how it may reflect the haptic perception of relative phase. Copyright © 2018 Elsevier B.V. All rights reserved.

Physics of Non-Inertial Reference Frames

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamalov, Timur F.

2010-12-22

Physics of non-inertial reference frames is a generalizing of Newton's laws to any reference frames. It is the system of general axioms for classical and quantum mechanics. The first, Kinematics Principle reads: the kinematic state of a body free of forces conserves and equal in absolute value to an invariant of the observer's reference frame. The second, Dynamics Principle extended Newton's second law to non-inertial reference frames and also contains additional variables there are higher derivatives of coordinates. Dynamics Principle reads: a force induces a change in the kinematic state of the body and is proportional to the rate ofmore » its change. It is mean that if the kinematic invariant of the reference frame is n-th derivative with respect the time, then the dynamics of a body being affected by the force F is described by the 2n-th differential equation. The third, Statics Principle reads: the sum of all forces acting a body at rest is equal to zero.« less

The assessment of the transformation of global tectonic plate models and the global terrestrial reference frames using the Velocity Decomposition Analysis

NASA Astrophysics Data System (ADS)

Ampatzidis, Dimitrios; König, Rolf; Glaser, Susanne; Heinkelmann, Robert; Schuh, Harald; Flechtner, Frank; Nilsson, Tobias

2016-04-01

The aim of our study is to assess the classical Helmert similarity transformation using the Velocity Decomposition Analysis (VEDA). The VEDA is a new methodology, developed by GFZ for the assessment of the reference frames' temporal variation and it is based on the separation of the velocities into two specified parts: The first is related to the reference system choice (the so called datum effect) and the latter one which refers to the real deformation of the terrestrial points. The advantage of the VEDA is its ability to detect the relative biases and reference system effects between two different frames or two different realizations of the same frame, respectively. We apply the VEDA for the assessment between several modern tectonic plate models and the recent global terrestrial reference frames.

Intra-Operative Dosimetry in Prostate Brachytherapy

DTIC Science & Technology

2007-11-01

of the focal spot. 2.1. Model for Reconstruction Space Transformation As illustrated in Figure 8, let A & B ( with reference frames FA & FB) be the two...simplex optimization method in MATLAB 7.0 with the search space being defined by the distortion modes from PCA. A linear combination of the modes would...arm is tracked with an X-ray fiducial system called FTRAC that is composed of optimally selected polynomial

Navigation System Design and State Estimation for a Small Rigid Hull Inflatable Boat (RHIB)

DTIC Science & Technology

2014-09-01

addition of the Coriolis term as previously defined has no effect on pitch, only one measurement is compared against Condor’s true pitch angle values...33  B.  REFERENCE FRAME DEFINITIONS ......................................................33  1.  Earth Centered Inertial...the effect of higher order terms. Lastly, the zeroth weight of the scaled weight set can be modified to incorporate prior knowledge of the

Three-Dimensional Modeling of Aircraft High-Lift Components with Vehicle Sketch Pad

NASA Technical Reports Server (NTRS)

Olson, Erik D.

2016-01-01

Vehicle Sketch Pad (OpenVSP) is a parametric geometry modeler that has been used extensively for conceptual design studies of aircraft, including studies using higher-order analysis. OpenVSP can model flap and slat surfaces using simple shearing of the airfoil coordinates, which is an appropriate level of complexity for lower-order aerodynamic analysis methods. For three-dimensional analysis, however, there is not a built-in method for defining the high-lift components in OpenVSP in a realistic manner, or for controlling their complex motions in a parametric manner that is intuitive to the designer. This paper seeks instead to utilize OpenVSP's existing capabilities, and establish a set of best practices for modeling high-lift components at a level of complexity suitable for higher-order analysis methods. Techniques are described for modeling the flap and slat components as separate three-dimensional surfaces, and for controlling their motion using simple parameters defined in the local hinge-axis frame of reference. To demonstrate the methodology, an OpenVSP model for the Energy-Efficient Transport (EET) AR12 wind-tunnel model has been created, taking advantage of OpenVSP's Advanced Parameter Linking capability to translate the motions of the high-lift components from the hinge-axis coordinate system to a set of transformations in OpenVSP's frame of reference.

Why the Greenwich Meridian Moved

DTIC Science & Technology

2015-08-01

that are related to the geocentric reference frame introduced by the Bureau International de l’Heure (BIH) in 1984. This BIHTerrestrial System provided...the basis for orientation of subsequent geocentric reference frames, including all realizations of theWorld Geodetic Sys- tem 1984 and the...astronomical time. The coordinates of satellite-navigation receivers are provided in reference frames that are related to the geocentric reference

Newton-Cartan Gravity in Noninertial Reference Frames

NASA Astrophysics Data System (ADS)

Rodriguez, Leo; St. Germaine-Fuller, James; Wickramasekara, Sujeev

2015-03-01

We study Newton-Cartan gravity under transformations into all noninertial, nonrelativistic reference frames. These transformations form an infinite dimensional Lie group, called the Galilean line group, which contains as a subgroup the Galilei group. The fictitious forces of noninertial reference frames are encoded in the Cartan connection transformed under the Galilean line group. These fictitious forces, which are coordinate effects, do not contribute to the Ricci tensor. Only the 00-component of the Ricci tensor is non-zero and equals (4 π times) the matter density in all reference frames. While the Ricci field equation and Gauss' law are fulfilled by the physical matter density in inertial and linearly accelerating reference frames, in rotating reference frames Gauss' law holds for an effective mass density that differs from the physical matter density. This effective density has its origin in the simulated magnetic field of rotating frames, highlighting a striking difference between linearly and rotationally accelerating frames. The equations governing the simulated fields have the same form as Maxwell's equations, a surprising result given that these equations obey special relativity (and U (1) -gauge symmetry), rather than Galilean symmetry. This work was supported in part by the HHMI Undergraduate Science Education Award 52006298 and the Grinnell College Academic Affairs' CSFS and MAP programs.

Report of the panel on earth rotation and reference frames, section 7

NASA Technical Reports Server (NTRS)

Dickey, Jean O.; Dickman, Steven R.; Eubanks, Marshall T.; Feissel, Martine; Herring, Thomas A.; Mueller, Ivan I.; Rosen, Richard D.; Schutz, Robert E.; Wahr, John M.; Wilson, Charles R.

1991-01-01

Objectives and requirements for Earth rotation and reference frame studies in the 1990s are discussed. The objectives are to observe and understand interactions of air and water with the rotational dynamics of the Earth, the effects of the Earth's crust and mantle on the dynamics and excitation of Earth rotation variations over time scales of hours to centuries, and the effects of the Earth's core on the rotational dynamics and the excitation of Earth rotation variations over time scales of a year or longer. Another objective is to establish, refine and maintain terrestrial and celestrial reference frames. Requirements include improvements in observations and analysis, improvements in celestial and terrestrial reference frames and reference frame connections, and improved observations of crustal motion and mass redistribution on the Earth.

TIGO: a geodetic observatory for the improvement of the global reference frame

NASA Astrophysics Data System (ADS)

Schlueter, Wolfgang; Hase, Hayo; Boeer, Armin

1999-12-01

The Bundesamt fuer Kartographie und Geodaesie (BKG) will provide a major contribution to the improvement and maintenance of the global reference frames: ICRF (International Celestial Reference Frame), ITRF (International Terrestrial Reference Frame) with the operation of TIGO (Transportable Integrated Geodetic Observatory). TIGO is designed as a transportable geodetic observatory which consists of all relevant geodetic space techniques for a fundamental station (including VLBI, SLR, GPS). The transportability of the observatory enables to fill up gaps in the International Space Geodetic Network and to optimize the contribution to the global reference frames. TIGO should operate for a period of 2 to 3 years (at minimum) at one location. BKG is looking for a cooperation with countries willing to contribute to the ITRF and to support the operation of TIGO.

Reliability of frames of reference used for tibial component rotation in total knee arthroplasty.

PubMed

Page, Stephen R; Deakin, Angela H; Payne, Anthony P; Picard, Frederic

2011-01-01

This study evaluated seven different frames of reference used for tibial component rotation in total knee arthroplasty (TKA) to determine which ones showed good reliability between bone specimens. An optoelectronic system based around a computer-assisted surgical navigation system was used to measure and locate 34 individual anatomical landmarks on 40 tibias. Each particular frame of reference was reconstructed from a group of data points taken from the surface of each bone. The transverse axis was used as the baseline to which the other axes were compared, and the differences in angular rotation between the other six reference frames and the transverse axis were calculated. There was high variability in the tibial rotational alignment associated with all frames of reference. Of the references widely used in current TKA procedures, the tibial tuberosity axis and the anterior condylar axis had lower standard deviations (6.1° and 7.3°, respectively) than the transmalleolar axis and the posterior condylar axis (9.3° for both). In conclusion, we found high variability in the frames of reference used for tibial rotation alignment. However, the anterior condylar axis and transverse axis may warrant further tests with the use of navigation. Combining different frames of reference such as the tibial tuberosity axis, anterior condylar axis and transverse axis may reduce the range of errors found in all of these measurements.

NChina16: A stable geodetic reference frame for geological hazard studies in North China

NASA Astrophysics Data System (ADS)

Wang, Guoquan; Bao, Yan; Gan, Weijun; Geng, Jianghui; Xiao, Gengru; Shen, Jack S.

2018-04-01

We have developed a stable North China Reference Frame 2016 (NChina16) using five years of continuous GPS observations (2011.8-2016.8) from 12 continuously operating reference stations (CORS) fixed to the North China Craton. Applications of NChina16 in landslide and subsidence studies are illustrated in this article. A method for realizing a regional geodetic reference frame is introduced. The primary result of this study is the seven parameters for transforming Cartesian ECEF (Earth-Centered, Earth-Fixed) coordinates X, Y, and Z from the International GNSS Service Reference Frame 2008 (IGS08) to NChina16. The seven parameters include the epoch that is used to align the regional reference frame to IGS08 and the time derivatives of three translations and three rotations. The GIPSY-OASIS (V6.4) software package was used to obtain the precise point positioning (PPP) daily solutions with respect to IGS08. The frame stability of NChina16 is approximately 0.5 mm/year in both horizontal and vertical directions. This study also developed a regional model for correcting seasonal motions superimposed into the vertical component of the GPS-derived displacement time series. Long-term GPS observations (1999-2016) from five CORS in North China were used to develop the seasonal model. According to this study, the PPP daily solutions with respect to NChina16 could achieve 2-3 mm horizontal accuracy and 4-5 mm vertical accuracy after being modified by the regional model. NChina16 will be critical to study geodynamic problems in North China, such as earthquakes, faulting, subsidence, and landslides. The regional reference frame will be periodically updated every few years to mitigate degradation of the frame with time and be synchronized with the update of IGS reference frame.

First steps of processing VLBI data of space probes with VieVS

NASA Astrophysics Data System (ADS)

Plank, L.; Böhm, J.; Schuh, H.

2011-07-01

Since 2008 the VLBI group at the Institute of Geodesy and Geophysics (IGG) of the Vienna University of Technology has developed the Vienna VLBI Software VieVS which is capable to process geodetic VLBI data in NGS format. Constantly we are working on upgrading the new software, e.g. by developing a scheduling tool or extending the software from single session solution to a so-called global solution, allowing the joint analysis of many sessions covering several years. In this presentation we report on first steps to enable the processing of space VLBI data with the software. Driven by the recently increasing number of space VLBI applications, our goal is the geodetic usage of such data, primarily concerning frame ties between various reference frames, e. g. by connecting the dynamic reference frame of a space probe with the kinematically defined International Celestial Reference Frame (ICRF). Main parts of the software extension w.r.t. the existing VieVS are the treatment of fast moving targets, the implementation of a delay model for radio emitters at finite distances, and the adequate mathematical model and adjustment of the particular unknowns. Actual work has been done for two mission scenarios so far: On the one hand differential VLBI (D-VLBI) data from the two sub-satellites of the Japanese lunar mission Selene were processed, on the other hand VLBI observations of GNSS satellites were modelled in VieVS. Besides some general aspects, we give details on the calculation of the theoretical delay (delay model for moving sources at finite distances) and its realization in VieVS. First results with real data and comparisons with best fit mission orbit data are also presented.'

A new mathematical model and control of a three-phase AC-DC voltage source converter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blasko, V.; Kaura, V.

1997-01-01

A new mathematical model of the power circuit of a three-phase voltage source converter (VSC) was developed in the stationary and synchronous reference frames. The mathematical model was then used to analyze and synthesize the voltage and current control loops for the VSC. Analytical expressions were derived for calculating the gains and time constants of the current and voltage regulators. The mathematical model was used to control a 140-kW regenerative VSC. The synchronous reference frame model was used to define feedforward signals in the current regulators to eliminate the cross coupling between the d and q phases. It allowed themore » reduction of the current control loop to first-order plants and improved their tracking capability. The bandwidths of the current and voltage-control loops were found to be approximately 20 and 60 times (respectively) smaller than the sampling frequency. All control algorithms were implemented in a digital-signal processor. All results of the analysis were experimentally verified.« less

Cerebellar re-encoding of self-generated head movements

PubMed Central

Dugué, Guillaume P; Tihy, Matthieu; Gourévitch, Boris; Léna, Clément

2017-01-01

Head movements are primarily sensed in a reference frame tied to the head, yet they are used to calculate self-orientation relative to the world. This requires to re-encode head kinematic signals into a reference frame anchored to earth-centered landmarks such as gravity, through computations whose neuronal substrate remains to be determined. Here, we studied the encoding of self-generated head movements in the rat caudal cerebellar vermis, an area essential for graviceptive functions. We found that, contrarily to peripheral vestibular inputs, most Purkinje cells exhibited a mixed sensitivity to head rotational and gravitational information and were differentially modulated by active and passive movements. In a subpopulation of cells, this mixed sensitivity underlay a tuning to rotations about an axis defined relative to gravity. Therefore, we show that the caudal vermis hosts a re-encoded, gravitationally polarized representation of self-generated head kinematics in freely moving rats. DOI: http://dx.doi.org/10.7554/eLife.26179.001 PMID:28608779

Allocentrically implied target locations are updated in an eye-centred reference frame.

PubMed

Thompson, Aidan A; Glover, Christopher V; Henriques, Denise Y P

2012-04-18

When reaching to remembered target locations following an intervening eye movement a systematic pattern of error is found indicating eye-centred updating of visuospatial memory. Here we investigated if implicit targets, defined only by allocentric visual cues, are also updated in an eye-centred reference frame as explicit targets are. Participants viewed vertical bars separated by varying distances, and horizontal lines of equivalently varying lengths, implying a "target" location at the midpoint of the stimulus. After determining the implied "target" location from only the allocentric stimuli provided, participants saccaded to an eccentric location, and reached to the remembered "target" location. Irrespective of the type of stimulus reaching errors to these implicit targets are gaze-dependent, and do not differ from those found when reaching to remembered explicit targets. Implicit target locations are coded and updated as a function of relative gaze direction with respect to those implied locations just as explicit targets are, even though no target is specifically represented. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Definition and Proposed Realization of the International Height Reference System (IHRS)

NASA Astrophysics Data System (ADS)

Ihde, Johannes; Sánchez, Laura; Barzaghi, Riccardo; Drewes, Hermann; Foerste, Christoph; Gruber, Thomas; Liebsch, Gunter; Marti, Urs; Pail, Roland; Sideris, Michael

2017-05-01

Studying, understanding and modelling global change require geodetic reference frames with an order of accuracy higher than the magnitude of the effects to be actually studied and with high consistency and reliability worldwide. The International Association of Geodesy, taking care of providing a precise geodetic infrastructure for monitoring the Earth system, promotes the implementation of an integrated global geodetic reference frame that provides a reliable frame for consistent analysis and modelling of global phenomena and processes affecting the Earth's gravity field, the Earth's surface geometry and the Earth's rotation. The definition, realization, maintenance and wide utilization of the International Terrestrial Reference System guarantee a globally unified geometric reference frame with an accuracy at the millimetre level. An equivalent high-precision global physical reference frame that supports the reliable description of changes in the Earth's gravity field (such as sea level variations, mass displacements, processes associated with geophysical fluids) is missing. This paper addresses the theoretical foundations supporting the implementation of such a physical reference surface in terms of an International Height Reference System and provides guidance for the coming activities required for the practical and sustainable realization of this system. Based on conceptual approaches of physical geodesy, the requirements for a unified global height reference system are derived. In accordance with the practice, its realization as the International Height Reference Frame is designed. Further steps for the implementation are also proposed.

Spatial reference frames of visual, vestibular, and multimodal heading signals in the dorsal subdivision of the medial superior temporal area.

PubMed

Fetsch, Christopher R; Wang, Sentao; Gu, Yong; Deangelis, Gregory C; Angelaki, Dora E

2007-01-17

Heading perception is a complex task that generally requires the integration of visual and vestibular cues. This sensory integration is complicated by the fact that these two modalities encode motion in distinct spatial reference frames (visual, eye-centered; vestibular, head-centered). Visual and vestibular heading signals converge in the primate dorsal subdivision of the medial superior temporal area (MSTd), a region thought to contribute to heading perception, but the reference frames of these signals remain unknown. We measured the heading tuning of MSTd neurons by presenting optic flow (visual condition), inertial motion (vestibular condition), or a congruent combination of both cues (combined condition). Static eye position was varied from trial to trial to determine the reference frame of tuning (eye-centered, head-centered, or intermediate). We found that tuning for optic flow was predominantly eye-centered, whereas tuning for inertial motion was intermediate but closer to head-centered. Reference frames in the two unimodal conditions were rarely matched in single neurons and uncorrelated across the population. Notably, reference frames in the combined condition varied as a function of the relative strength and spatial congruency of visual and vestibular tuning. This represents the first investigation of spatial reference frames in a naturalistic, multimodal condition in which cues may be integrated to improve perceptual performance. Our results compare favorably with the predictions of a recent neural network model that uses a recurrent architecture to perform optimal cue integration, suggesting that the brain could use a similar computational strategy to integrate sensory signals expressed in distinct frames of reference.

Mapping From an Instrumented Glove to a Robot Hand

NASA Technical Reports Server (NTRS)

Goza, Michael

2005-01-01

An algorithm has been developed to solve the problem of mapping from (1) a glove instrumented with joint-angle sensors to (2) an anthropomorphic robot hand. Such a mapping is needed to generate control signals to make the robot hand mimic the configuration of the hand of a human attempting to control the robot. The mapping problem is complicated by uncertainties in sensor locations caused by variations in sizes and shapes of hands and variations in the fit of the glove. The present mapping algorithm is robust in the face of these uncertainties, largely because it includes a calibration sub-algorithm that inherently adapts the mapping to the specific hand and glove, without need for measuring the hand and without regard for goodness of fit. The algorithm utilizes a forward-kinematics model of the glove derived from documentation provided by the manufacturer of the glove. In this case, forward-kinematics model signifies a mathematical model of the glove fingertip positions as functions of the sensor readings. More specifically, given the sensor readings, the forward-kinematics model calculates the glove fingertip positions in a Cartesian reference frame nominally attached to the palm. The algorithm also utilizes an inverse-kinematics model of the robot hand. In this case, inverse-kinematics model signifies a mathematical model of the robot finger-joint angles as functions of the robot fingertip positions. Again, more specifically, the inverse-kinematics model calculates the finger-joint commands needed to place the fingertips at specified positions in a Cartesian reference frame that is attached to the palm of the robot hand and that nominally corresponds to the Cartesian reference frame attached to the palm of the glove. Initially, because of the aforementioned uncertainties, the glove fingertip positions calculated by the forwardkinematics model in the glove Cartesian reference frame cannot be expected to match the robot fingertip positions in the robot-hand Cartesian reference frame. A calibration must be performed to make the glove and robot-hand fingertip positions correspond more precisely. The calibration procedure involves a few simple hand poses designed to provide well-defined fingertip positions. One of the poses is a fist. In each of the other poses, a finger touches the thumb. The calibration subalgorithm uses the sensor readings from these poses to modify the kinematical models to make the two sets of fingertip positions agree more closely.

Asynchronous reference frame agreement in a quantum network

NASA Astrophysics Data System (ADS)

Islam, Tanvirul; Wehner, Stephanie

2016-03-01

An efficient implementation of many multiparty protocols for quantum networks requires that all the nodes in the network share a common reference frame. Establishing such a reference frame from scratch is especially challenging in an asynchronous network where network links might have arbitrary delays and the nodes do not share synchronised clocks. In this work, we study the problem of establishing a common reference frame in an asynchronous network of n nodes of which at most t are affected by arbitrary unknown error, and the identities of the faulty nodes are not known. We present a protocol that allows all the correctly functioning nodes to agree on a common reference frame as long as the network graph is complete and not more than t\\lt n/4 nodes are faulty. As the protocol is asynchronous, it can be used with some assumptions to synchronise clocks over a network. Also, the protocol has the appealing property that it allows any existing two-node asynchronous protocol for reference frame agreement to be lifted to a robust protocol for an asynchronous quantum network.

Mercury's Reference Frames After the MESSENGER Mission

NASA Astrophysics Data System (ADS)

Stark, A.; Oberst, J.; Preusker, F.; Burmeister, S.; Steinbrügge, G.; Hussmann, H.

2018-05-01

We provide an overview of Mercury's reference frames based on MESSENGER observations. We discuss the dynamical, the principal-axes, the ellipsoid, as well as the cartographic frame, which was adopted for MESSENGER data products.

Foveal Machine Vision Systems

DTIC Science & Technology

1990-08-01

12 The smallest regions defined by the superposition of the rexel boundaries of all the frames will be referred to as unisource regions. 85I I Chapter... unisource region are identical. I The advantage of rexel formatted data is its small size. However, the storage of rexel data in a uniform two...dimensional array is difficult because unisource regions can take on a wide variety of shapes. Rexel data can be stored in thinned uniform arrays, but this

Determination of Galactic Aberration from VLBI Measurements and Its Effect on VLBI Reference Frames and Earth Orientation Parameters.

NASA Astrophysics Data System (ADS)

MacMillan, D. S.

2014-12-01

Galactic aberration is due to the motion of the solar system barycenter around the galactic center. It results in a systematic pattern of apparent proper motion of radio sources observed by VLBI. This effect is not currently included in VLBI analysis. Estimates of the size of this effect indicate that it is important that this secular aberration drift be accounted for in order to maintain an accurate celestial reference frame and allow astrometry at the several microarcsecond level. Future geodetic observing systems are being designed to be capable of producing a future terrestrial reference frame with an accuracy of 1 mm and stability of 0.1 mm/year. We evaluate the effect galactic aberration on attaining these reference frame goals. This presentation will discuss 1) the estimation of galactic aberration from VLBI data and 2) the effect of aberration on the Terrestrial and Celestial Reference Frames and the Earth Orientation Parameters that connect these frames.

Multiple reference frames in haptic spatial processing

NASA Astrophysics Data System (ADS)

Volčič, R.

2008-08-01

The present thesis focused on haptic spatial processing. In particular, our interest was directed to the perception of spatial relations with the main focus on the perception of orientation. To this end, we studied haptic perception in different tasks, either in isolation or in combination with vision. The parallelity task, where participants have to match the orientations of two spatially separated bars, was used in its two-dimensional and three-dimensional versions in Chapter 2 and Chapter 3, respectively. The influence of non-informative vision and visual interference on performance in the parallelity task was studied in Chapter 4. A different task, the mental rotation task, was introduced in a purely haptic study in Chapter 5 and in a visuo-haptic cross-modal study in Chapter 6. The interaction of multiple reference frames and their influence on haptic spatial processing were the common denominators of these studies. In this thesis we approached the problems of which reference frames play the major role in haptic spatial processing and how the relative roles of distinct reference frames change depending on the available information and the constraints imposed by different tasks. We found that the influence of a reference frame centered on the hand was the major cause of the deviations from veridicality observed in both the two-dimensional and three-dimensional studies. The results were described by a weighted average model, in which the hand-centered egocentric reference frame is supposed to have a biasing influence on the allocentric reference frame. Performance in haptic spatial processing has been shown to depend also on sources of information or processing that are not strictly connected to the task at hand. When non-informative vision was provided, a beneficial effect was observed in the haptic performance. This improvement was interpreted as a shift from the egocentric to the allocentric reference frame. Moreover, interfering visual information presented in the vicinity of the haptic stimuli parametrically modulated the magnitude of the deviations. The influence of the hand-centered reference frame was shown also in the haptic mental rotation task where participants were quicker in judging the parity of objects when these were aligned with respect to the hands than when they were physically aligned. Similarly, in the visuo-haptic cross-modal mental rotation task the parity judgments were influenced by the orientation of the exploring hand with respect to the viewing direction. This effect was shown to be modulated also by an intervening temporal delay that supposedly counteracts the influence of the hand-centered reference frame. We suggest that the hand-centered reference frame is embedded in a hierarchical structure of reference frames where some of these emerge depending on the demands and the circumstances of the surrounding environment and the needs of an active perceiver.

Rapid formation of spatiotopic representations as revealed by inhibition of return.

PubMed

Pertzov, Yoni; Zohary, Ehud; Avidan, Galia

2010-06-30

Inhibition of return (IOR), a performance decrement for stimuli appearing at recently cued locations, occurs when the target and cue share the same screen position. This is in contrast to cue-based attention facilitation effects that were recently suggested to be mapped in a retinotopic reference frame, the prevailing representation throughout early visual processing stages. Here, we investigate the dynamics of IOR in both reference frames, using a modified cued-location saccadic reaction time task with an intervening saccade between cue and target presentation. Thus, on different trials, the target was present either at the same retinotopic location as the cue, or at the same screen position (e.g., spatiotopic location). IOR was primarily found for targets appearing at the same spatiotopic position as the initial cue, when the cue and target were presented at the same hemifield. This suggests that there is restricted information transfer of cue position across the two hemispheres. Moreover, the effect was maximal when the target was presented 10 ms after the intervening saccade ended and was attenuated in longer delays. In our case, therefore, the representation of previously attended locations (as revealed by IOR) is not remapped slowly after the execution of a saccade. Rather, either a retinotopic representation is remapped rapidly, adjacent to the end of the saccade (using a prospective motor command), or the positions of the cue and target are encoded in a spatiotopic reference frame, regardless of eye position. Spatial attention can therefore be allocated to target positions defined in extraretinal coordinates.

Reference Frames in Relativistic Space-Time

NASA Astrophysics Data System (ADS)

Soffel, M.; Herold, H.; Ruder, H.; Schneider, M.

Three fundamental concepts of reference frames in relativistic space-time are confronted: 1. the gravitation compass, 2. the stellar compass and 3. the inertial compass. It is argued that under certain conditions asymptotically fixed (stellar) reference frames can be introduced with the same rigour as local Fermi frames, thereby eliminating one possible psychological reason why the importance of Fermi frames frequently has been overestimated in the past. As applications of these three concepts the authors discuss: 1. a relativistic definition of the geoid, 2. a relativistic astrometric problem and 3. the post-Newtonian theory of a laser gyroscope fixed to the Earth's surface.

Different reference frames can lead to different hand transplantation decisions by patients and physicians.

PubMed

Edgell, S E; McCabe, S J; Breidenbach, W C; Neace, W P; LaJoie, A S; Abell, T D

2001-03-01

Different frames of reference can affect one's assessment of the value of hand transplantation. This can result in different yet rational decisions by different groups of individuals, especially patients and physicians. In addition, factors other than frames of reference can affect one's evaluation of hand transplantation, which can result in different decisions.

SAIP2014, the 59th Annual Conference of the South African Institute of Physics

NASA Astrophysics Data System (ADS)

Engelbrecht, Chris; Karataglidis, Steven

2015-04-01

The International Celestial Reference Frame (ICRF) was adopted by the International Astronomical Union (IAU) in 1997. The current standard, the ICRF-2, is based on Very Long Baseline Interferometric (VLBI) radio observations of positions of 3414 extragalactic radio reference sources. The angular resolution achieved by the VLBI technique is on a scale of milliarcsecond to sub-milliarcseconds and defines the ICRF with the highest accuracy available at present. An ideal reference source used for celestial reference frame work should be unresolved or point-like on these scales. However, extragalactic radio sources, such as those that definevand maintain the ICRF, can exhibit spatially extended structures on sub-milliarsecond scalesvthat may vary both in time and frequency. This variability can introduce a significant error in the VLBI measurements thereby degrading the accuracy of the estimated source position. Reference source density in the Southern celestial hemisphere is also poor compared to the Northern hemisphere, mainly due to the limited number of radio telescopes in the south. In order to dene the ICRF with the highest accuracy, observational efforts are required to find more compact sources and to monitor their structural evolution. In this paper we show that the astrometric VLBI sessions can be used to obtain source structure information and we present preliminary imaging results for the source J1427-4206 at 2.3 and 8.4 GHz frequencies which shows that the source is compact and suitable as a reference source.

Application of Millisecond Pulsar Timing to the Long-Term Stability of Clock Ensembles

NASA Technical Reports Server (NTRS)

Foster, Roger S.; Matsakis, Demetrios N.

1996-01-01

We review the application of millisecond pulsars to define a precise long-term standard and positional reference system in a nearly inertial reference frame. We quantify the current timing precision of the best millisecond pulsars and define the required precise time and time interval (PTTI) accuracy and stability to enable time transfer via pulsars. Pulsars may prove useful as independent standards to examine decade-long timing stability and provide an independent natural system within which to calibrate any new, perhaps vastly improved atomic time scale. Since pulsar stability appears to be related to the lifetime of the pulsar, the new millisecond pulsar J173+0747 is projected to have a 100-day accuracy equivalent to a single HP5071 cesium standard. Over the last five years, dozens of new millisecond pulsars have been discovered. A few of the new millisecond pulsars may have even better timing properties.

Quantum reference frames and their applications to thermodynamics.

PubMed

Popescu, Sandu; Sainz, Ana Belén; Short, Anthony J; Winter, Andreas

2018-07-13

We construct a quantum reference frame, which can be used to approximately implement arbitrary unitary transformations on a system in the presence of any number of extensive conserved quantities, by absorbing any back action provided by the conservation laws. Thus, the reference frame at the same time acts as a battery for the conserved quantities. Our construction features a physically intuitive, clear and implementation-friendly realization. Indeed, the reference system is composed of the same types of subsystems as the original system and is finite for any desired accuracy. In addition, the interaction with the reference frame can be broken down into two-body terms coupling the system to one of the reference frame subsystems at a time. We apply this construction to quantum thermodynamic set-ups with multiple, possibly non-commuting conserved quantities, which allows for the definition of explicit batteries in such cases.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'. © 2018 The Author(s).

Error reduction in three-dimensional metrology combining optical and touch probe data

NASA Astrophysics Data System (ADS)

Gerde, Janice R.; Christens-Barry, William A.

2010-08-01

Analysis of footwear under the Harmonized Tariff Schedule of the United States (HTSUS) is partly based on identifying the boundary ("parting line") between the "external surface area upper" (ESAU) and the sample's sole. Often, that boundary is obscured. We establish the parting line as the curved intersection between the sample outer surface and its insole surface. The outer surface is determined by discrete point cloud coordinates obtained using a laser scanner. The insole surface is defined by point cloud data, obtained using a touch probe device-a coordinate measuring machine (CMM). Because these point cloud data sets do not overlap spatially, a polynomial surface is fitted to the insole data and extended to intersect a mesh fitted to the outer surface point cloud. This line of intersection defines the ESAU boundary, permitting further fractional area calculations to proceed. The defined parting line location is sensitive to the polynomial used to fit experimental data. Extrapolation to the intersection with the ESAU can heighten this sensitivity. We discuss a methodology for transforming these data into a common reference frame. Three scenarios are considered: measurement error in point cloud coordinates, from fitting a polynomial surface to a point cloud then extrapolating beyond the data set, and error from reference frame transformation. These error sources can influence calculated surface areas. We describe experiments to assess error magnitude, the sensitivity of calculated results on these errors, and minimizing error impact on calculated quantities. Ultimately, we must ensure that statistical error from these procedures is minimized and within acceptance criteria.

The Reciprocal Internal/External Frame of Reference Model: An Integration of Models of Relations between Academic Achievement and Self-Concept

ERIC Educational Resources Information Center

Moller, Jens; Retelsdorf, Jan; Koller, Olaf; Marsh, Herb W.

2011-01-01

The reciprocal internal/external frame of reference model (RI/EM) combines the internal/external frame of reference model and the reciprocal effects model. The RI/EM predicts positive effects of mathematics and verbal achievement and academic self-concepts (ASC) on subsequent mathematics and verbal achievements and ASCs within domains and negative…

Current control of PMSM based on maximum torque control reference frame

NASA Astrophysics Data System (ADS)

Ohnuma, Takumi

2017-07-01

This study presents a new method of current controls of PMSMs (Permanent Magnet Synchronous Motors) based on a maximum torque control reference frame, which is suitable for high-performance controls of the PMSMs. As the issues of environment and energy increase seriously, PMSMs, one of the AC motors, are becoming popular because of their high-efficiency and high-torque density in various applications, such as electric vehicles, trains, industrial machines, and home appliances. To use the PMSMs efficiently, a proper current control of the PMSMs is necessary. In general, a rotational coordinate system synchronizing with the rotor is used for the current control of PMSMs. In the rotating reference frame, the current control is easier because the currents on the rotating reference frame can be expressed as a direct current in the controller. On the other hand, the torque characteristics of PMSMs are non-linear and complex; the PMSMs are efficient and high-density though. Therefore, a complicated control system is required to involve the relation between the torque and the current, even though the rotating reference frame is adopted. The maximum torque control reference frame provides a simpler way to control efficiently the currents taking the torque characteristics of the PMSMs into consideration.

Mechanical Energy Change in Inertial Reference Frames

ERIC Educational Resources Information Center

Ghanbari, Saeed

2016-01-01

The mechanical energy change of a system in an inertial frame of reference equals work done by the total nonconservative force in the same frame. This relation is covariant under the Galilean transformations from inertial frame S to S', where S' moves with constant velocity relative to S. In the presence of nonconservative forces, such as normal…

Automatic frame-centered object representation and integration revealed by iconic memory, visual priming, and backward masking.

PubMed

Lin, Zhicheng; He, Sheng

2012-10-25

Object identities ("what") and their spatial locations ("where") are processed in distinct pathways in the visual system, raising the question of how the what and where information is integrated. Because of object motions and eye movements, the retina-based representations are unstable, necessitating nonretinotopic representation and integration. A potential mechanism is to code and update objects according to their reference frames (i.e., frame-centered representation and integration). To isolate frame-centered processes, in a frame-to-frame apparent motion configuration, we (a) presented two preceding or trailing objects on the same frame, equidistant from the target on the other frame, to control for object-based (frame-based) effect and space-based effect, and (b) manipulated the target's relative location within its frame to probe frame-centered effect. We show that iconic memory, visual priming, and backward masking depend on objects' relative frame locations, orthogonal of the retinotopic coordinate. These findings not only reveal that iconic memory, visual priming, and backward masking can be nonretinotopic but also demonstrate that these processes are automatically constrained by contextual frames through a frame-centered mechanism. Thus, object representation is robustly and automatically coupled to its reference frame and continuously being updated through a frame-centered, location-specific mechanism. These findings lead to an object cabinet framework, in which objects ("files") within the reference frame ("cabinet") are orderly coded relative to the frame.

Evaluating a hybrid three-dimensional metrology system: merging data from optical and touch probe devices

NASA Astrophysics Data System (ADS)

Gerde, Janice R.; Christens-Barry, William A.

2011-08-01

In a project to meet requirements for CBP Laboratory analysis of footwear under the Harmonized Tariff Schedule of the United States (HTSUS), a hybrid metrology system comprising both optical and touch probe devices has been assembled. A unique requirement must be met: To identify the interface-typically obscured in samples of concern-of the "external surface area upper" (ESAU) and the sole without physically destroying the sample. The sample outer surface is determined by discrete point cloud coordinates obtained using laser scanner optical measurements. Measurements from the optically inaccessible insole region are obtained using a coordinate measuring machine (CMM). That surface similarly is defined by point cloud data. Mathematically, the individual CMM and scanner data sets are transformed into a single, common reference frame. Custom software then fits a polynomial surface to the insole data and extends it to intersect the mesh fitted to the outer surface point cloud. This line of intersection defines the required ESAU boundary, thus permitting further fractional area calculations to determine the percentage of materials present. With a draft method in place, and first-level method validation underway, we examine the transformation of the two dissimilar data sets into the single, common reference frame. We also will consider the six previously-identified potential error factors versus the method process. This paper reports our on-going work and discusses our findings to date.

Support time-dependent transformations for surveying and GIS : current status and upcoming challenges

NASA Astrophysics Data System (ADS)

Mahmoudabadi, H.; Lercier, D.; Vielliard, S.; Mein, N.; Briggs, G.

2016-12-01

The support of time-dependent transformations for surveying and GIS is becoming a critical issue. We need to convert positions from the realizations of the International Terrestrial Reference Frame to any national reference frame. This problem is easy to solve when all of the required information is available. But it becomes really complicated in a worldwide context. We propose an overview of the current ITRF-aligned reference frames and we describe a global solution to support time-dependent transformations between them and the International Terrestrial Reference Frame. We focus on the uncertainties of station velocities used. In a first approximation, we use a global tectonic plate model to calculate point velocities. We show the impact of the velocity model on the coordinate accuracies. Several countries, particularly in active regions, are developing semi-dynamic reference frames. These frames include local displacement models updated regularly and/or after major events (such as earthquakes). Their integration into surveying or GIS applications is an upcoming challenge. We want to encourage the geodetic community to develop and use standard formats.

Kinematics of Laying an Automated Weapon System

DTIC Science & Technology

2017-07-19

mathematical transformation is required to move the firing solution from its reference frame to a reference frame that is meaningful to the weapon system. This...Procedures 2 Conventions and Variable Definitions 2 Rotation Matrices 5 Transformation of a Vector 5 Conversion Between Cartestian and Spherical...Coordinate Systems 6 Transformation of Earth Referenced Lay to Platform Reference Frame 6 Results and Discussions 7 Conclusions 8 Bibliography 9

Differential School Contextual Effects for Math and English: Integrating the Big-Fish-Little-Pond Effect and the Internal/External Frame of Reference

ERIC Educational Resources Information Center

Parker, Philip D.; Marsh, Herbert W.; Ludtke, Oliver; Trautwein, Ulrich

2013-01-01

The internal/external frame of reference and the big-fish-little-pond effect are two major models of academic self-concept formation which have considerable theoretical and empirical support. Integrating the domain specific and compensatory processes of the internal/external frame of reference model with the big-fish-little-pond effect suggests a…

Framing Effects: Dynamics and Task Domains

PubMed

Wang

1996-11-01

The author examines the mechanisms and dynamics of framing effects in risky choices across three distinct task domains (i.e., life-death, public property, and personal money). The choice outcomes of the problems presented in each of the three task domains had a binary structure of a sure thing vs a gamble of equal expected value; the outcomes differed in their framing conditions and the expected values, raging from 6000, 600, 60, to 6, numerically. It was hypothesized that subjects would become more risk seeking, if the sure outcome was below their aspiration level (the minimum requirement). As predicted, more subjects preferred the gamble when facing the life-death choice problems than facing the counterpart problems presented in the other two task domains. Subjects' risk preference varied categorically along the group size dimension in the life-death domain but changed more linearly over the expected value dimension in the monetary domain. Framing effects were observed in 7 of 13 pairs of problems, showing a positive frame-risk aversion and negative frame-risk seeking relationship. In addition, two types of framing effects were theoretically defined and empirically identified. A bidirectional framing effect involves a reversal in risk preference, and occurs when a decision maker's risk preference is ambiguous or weak. Four bidirectional effects were observed; in each case a majority of subjects preferred the sure outcome under a positive frame but the gamble under a negative frame. In contrast, a unidirectional framing effect refers to a preference shift due to the framing of choice outcomes: A majority of subjects preferred one choice outcome (either the sure thing or the gamble) under both framing conditions, with positive frame augmented the preference for the sure thing and negative frame augmented the preference for the gamble. These findings revealed some dynamic regularities of framing effects and posed implications for developing predictive and testable models of human decision making.

The International Celestial Reference Frame (ICRF) and the Relationship Between Frames

NASA Technical Reports Server (NTRS)

Ma, Chopo

2000-01-01

The International Celestial Reference Frame (ICRF), a catalog of VLBI source positions, is now the basis for astrometry and geodesy. Its construction and extension/maintenance will be discussed as well as the relationship of the ICRF, ITRF, and EOP/nutation.

Networked Mediated Influence 2.0

DTIC Science & Technology

2014-12-12

but they communicate the information through different frames of reference. . . . Frames work by accessing a particular perspective on an issue...nature yet attention grabbers.214 Framing. A form of communications where information is presented in a unique slant, focal point, or frame of reference...mental frameworks differ in their implications for decision making, the results can be dramatic.215 Information Communication Technologies (ICTs). A term

What a speaker's choice of frame reveals: reference points, frame selection, and framing effects.

PubMed

McKenzie, Craig R M; Nelson, Jonathan D

2003-09-01

Framing effects are well established: Listeners' preferences depend on how outcomes are described to them, or framed. Less well understood is what determines how speakers choose frames. Two experiments revealed that reference points systematically influenced speakers' choices between logically equivalent frames. For example, speakers tended to describe a 4-ounce cup filled to the 2-ounce line as half full if it was previously empty but described it as half empty if it was previously full. Similar results were found when speakers could describe the outcome of a medical treatment in terms of either mortality or survival (e.g., 25% die vs. 75% survive). Two additional experiments showed that listeners made accurate inferences about speakers' reference points on the basis of the selected frame (e.g., if a speaker described a cup as half empty, listeners inferred that the cup used to be full). Taken together, the data suggest that frames reliably convey implicit information in addition to their explicit content, which helps explain why framing effects are so robust.

Updating of visual orientation in a gravity-based reference frame.

PubMed

Niehof, Nynke; Tramper, Julian J; Doeller, Christian F; Medendorp, W Pieter

2017-10-01

The brain can use multiple reference frames to code line orientation, including head-, object-, and gravity-centered references. If these frames change orientation, their representations must be updated to keep register with actual line orientation. We tested this internal updating during head rotation in roll, exploiting the rod-and-frame effect: The illusory tilt of a vertical line surrounded by a tilted visual frame. If line orientation is stored relative to gravity, these distortions should also affect the updating process. Alternatively, if coding is head- or frame-centered, updating errors should be related to the changes in their orientation. Ten subjects were instructed to memorize the orientation of a briefly flashed line, surrounded by a tilted visual frame, then rotate their head, and subsequently judge the orientation of a second line relative to the memorized first while the frame was upright. Results showed that updating errors were mostly related to the amount of subjective distortion of gravity at both the initial and final head orientation, rather than to the amount of intervening head rotation. In some subjects, a smaller part of the updating error was also related to the change of visual frame orientation. We conclude that the brain relies primarily on a gravity-based reference to remember line orientation during head roll.

Celestial reference frames and the gauge freedom in the post-Newtonian mechanics of the Earth-Moon system

NASA Astrophysics Data System (ADS)

Kopeikin, Sergei; Xie, Yi

2010-11-01

We introduce the Jacobi coordinates adopted to the advanced theoretical analysis of the relativistic Celestial Mechanics of the Earth-Moon system. Theoretical derivation utilizes the relativistic resolutions on reference frames adopted by the International Astronomical Union (IAU) in 2000. The resolutions assume that the Solar System is isolated and space-time is asymptotically flat at infinity and the primary reference frame covers the entire space-time, has its origin at the Solar System barycenter (SSB) with spatial axes stretching up to infinity. The SSB frame is not rotating with respect to a set of distant quasars that are assumed to be at rest on the sky forming the International Celestial Reference Frame (ICRF). The second reference frame has its origin at the Earth-Moon barycenter (EMB). The EMB frame is locally inertial and is not rotating dynamically in the sense that equation of motion of a test particle moving with respect to the EMB frame, does not contain the Coriolis and centripetal forces. Two other local frames—geocentric and selenocentric—have their origins at the center of mass of Earth and Moon respectively and do not rotate dynamically. Each local frame is subject to the geodetic precession both with respect to other local frames and with respect to the ICRF because of their relative motion with respect to each other. Theoretical advantage of the dynamically non-rotating local frames is in a more simple mathematical description of the metric tensor and relative equations of motion of the Moon with respect to Earth. Each local frame can be converted to kinematically non-rotating one after alignment with the axes of ICRF by applying the matrix of the relativistic precession as recommended by the IAU resolutions. The set of one global and three local frames is introduced in order to decouple physical effects of gravity from the gauge-dependent effects in the equations of relative motion of the Moon with respect to Earth.

Thinking inside the box: Spatial frames of reference for drawing in Williams syndrome and typical development.

PubMed

Hudson, Kerry D; Farran, Emily K

2017-09-01

Successfully completing a drawing relies on the ability to accurately impose and manipulate spatial frames of reference for the object that is being drawn and for the drawing space. Typically developing (TD) children use cues such as the page boundary as a frame of reference to guide the orientation of drawn lines. Individuals with Williams syndrome (WS) typically produce incohesive drawings; this is proposed to reflect a local processing bias. Across two studies, we provide the first investigation of the effect of using a frame of reference when drawing simple lines and shapes in WS and TD groups (matched for non-verbal ability). Individuals with WS (N=17 Experiment 1; N=18 Experiment 2) and TD children matched by non-verbal ability drew single lines (Experiment One) and whole shapes (Experiment Two) within a neutral, incongruent or congruent frame. The angular deviation of the drawn line/shape, relative to the model line/shape, was measured. Both groups were sensitive to spatial frames of reference when drawing single lines and whole shapes, imposed by a frame around the drawing space. A local processing bias in WS cannot explain poor drawing performance in WS. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Post-Newtonian Reference Frames for Advanced Theory of the Lunar Motion and a New Generation of Lunar Laser Ranging

NASA Astrophysics Data System (ADS)

Xie, Yi; Kopeikin, Sergei Affiliaiton: AB(Department of Physics and Astronomy, University of Missouri, USA kopeikins@missouri.edu)

2010-08-01

We overview a set of post-Newtonian reference frames for a comprehensive study of the orbital dynamics and rotational motion of Moon and Earth by means of lunar laser ranging (LLR). We employ a scalar-tensor theory of gravity depending on two post-Newtonian parameters, and , and utilize the relativistic resolutions on reference frames adopted by the International Astronomical Union (IAU) in 2000. We assume that the solar system is isolated and space-time is asymptotically flat at infinity. The primary reference frame covers the entire space-time, has its origin at the solar-system barycenter (SSB) and spatial axes stretching up to infinity. The SSB frame is not rotating with respect to a set of distant quasars that are forming the International Celestial Reference Frame (ICRF). The secondary reference frame has its origin at the Earth-Moon barycenter (EMB). The EMB frame is locally-inertial and is not rotating dynamically in the sense that equation of motion of a test particle moving with respect to the EMB frame, does not contain the Coriolis and centripetal forces. Two other local frames geocentric (GRF) and selenocentric (SRF) have their origins at the center of mass of Earth and Moon respectively and do not rotate dynamically. Each local frame is subject to the geodetic precession both with respect to other local frames and with respect to the ICRF because of their relative motion with respect to each other. Theoretical advantage of the dynamically non-rotating local frames is in a more simple mathematical description. Each local frame can be aligned with the axes of ICRF after applying the matrix of the relativistic precession. The set of one global and three local frames is introduced in order to fully decouple the relative motion of Moon with respect to Earth from the orbital motion of the Earth-Moon barycenter as well as to connect the coordinate description of the lunar motion, an observer on Earth, and a retro-reflector on Moon to directly measurable quantities such as the proper time and the round-trip laser-light distance. We solve the gravity field equations and find out the metric tensor and the scalar field in all frames which description includes the post-Newtonian multipole moments of the gravitational field of Earth and Moon. We also derive the post-Newtonian coordinate transformations between the frames and analyze the residual gauge freedom.

The influence of visual and vestibular orientation cues in a clock reading task.

PubMed

Davidenko, Nicolas; Cheong, Yeram; Waterman, Amanda; Smith, Jacob; Anderson, Barrett; Harmon, Sarah

2018-05-23

We investigated how performance in the real-life perceptual task of analog clock reading is influenced by the clock's orientation with respect to egocentric, gravitational, and visual-environmental reference frames. In Experiment 1, we designed a simple clock-reading task and found that observers' reaction time to correctly tell the time depends systematically on the clock's orientation. In Experiment 2, we dissociated egocentric from environmental reference frames by having participants sit upright or lie sideways while performing the task. We found that both reference frames substantially contribute to response times in this task. In Experiment 3, we placed upright or rotated participants in an upright or rotated immersive virtual environment, which allowed us to further dissociate vestibular from visual cues to the environmental reference frame. We found evidence of environmental reference frame effects only when visual and vestibular cues were aligned. We discuss the implications for the design of remote and head-mounted displays. Copyright © 2018 Elsevier Inc. All rights reserved.

Recovery of a geocentric reference frame using the present-day GPS system

NASA Technical Reports Server (NTRS)

Malla, Rajendra P.; Wu, Sien-Chong

1990-01-01

A geocentric reference frame adopts the center of mass of the earth as the origin of the coordinate axes. The center of mass of the earth is the natural and unambiguous origin of a geocentric satellite dynamical system. But in practice a kinematically obtained terrestrial reference frame may assume an origin other than the geocenter. The establishment of a geocentric reference frame, to which all relevant observations and results can be referred and in which geodynamic theories or models for the dynamic behavior of earth can be formulated, requires the ability to accurately recover a given coordinate frame origin offset from the geocenter. GPS measurements, because of their abundance and broad distribution, provide a powerful tool to obtain this origin offset in a short period of time. Two effective strategies have been devised. Data from the First Central And South America (Casa Uno) geodynamics experiment has been studied, in order to demonstrate the ability of recovering the geocenter location with present day GPS satellites and receivers.

Automatic frame-centered object representation and integration revealed by iconic memory, visual priming, and backward masking

PubMed Central

Lin, Zhicheng; He, Sheng

2012-01-01

Object identities (“what”) and their spatial locations (“where”) are processed in distinct pathways in the visual system, raising the question of how the what and where information is integrated. Because of object motions and eye movements, the retina-based representations are unstable, necessitating nonretinotopic representation and integration. A potential mechanism is to code and update objects according to their reference frames (i.e., frame-centered representation and integration). To isolate frame-centered processes, in a frame-to-frame apparent motion configuration, we (a) presented two preceding or trailing objects on the same frame, equidistant from the target on the other frame, to control for object-based (frame-based) effect and space-based effect, and (b) manipulated the target's relative location within its frame to probe frame-centered effect. We show that iconic memory, visual priming, and backward masking depend on objects' relative frame locations, orthogonal of the retinotopic coordinate. These findings not only reveal that iconic memory, visual priming, and backward masking can be nonretinotopic but also demonstrate that these processes are automatically constrained by contextual frames through a frame-centered mechanism. Thus, object representation is robustly and automatically coupled to its reference frame and continuously being updated through a frame-centered, location-specific mechanism. These findings lead to an object cabinet framework, in which objects (“files”) within the reference frame (“cabinet”) are orderly coded relative to the frame. PMID:23104817

GPS-Only Terrestrial Reference Frame Based on a Global Reprocessing

NASA Astrophysics Data System (ADS)

Dietrich, R.; Rothacher, M.; Ruelke, A.; Fritsche, M.; Steigenberger, P.

2007-12-01

The realization of the International Terrestrial Reference System (ITRS) with highest accuracy and stability is fundamental and crucial for applications in geodesy, geodynamics, geophysics and global change. In a joint effort TU Dresden and TU Munich/GFZ Potsdam reprocessed a global GPS network of more than 200 stations. As a contribution to an ITRS realization daily normal equations from 1994 to 2005 were rigorously combined in order to determine a global GPS-only reference frame (PDR05/Potsdam-Dresden-Reprocessing Reference Frame). We present a realization of the global terrestrial reference system which follows the center of mass approach in consideration of the load-induced deformation of the Earth's crust due to the redistribution of surface masses. The stability of our reference frame will be evaluated based on the obtained long-term trends of station coordinates, the load-induced deformation estimates and the homogeneous time series of station positions. We will compare our solution with other recent terrestrial reference system realizations and give some conclusions for future realizations of the ITRS.

Unification of height systems in the frame of GGOS

NASA Astrophysics Data System (ADS)

Sánchez, Laura

2015-04-01

Most of the existing vertical reference systems do not fulfil the accuracy requirements of modern Geodesy. They refer to local sea surface levels, are stationary (do not consider variations in time), realize different physical height types (orthometric, normal, normal-orthometric, etc.), and their combination in a global frame presents uncertainties at the metre level. To provide a precise geodetic infrastructure for monitoring the Earth system, the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG), promotes the standardization of the height systems worldwide. The main purpose is to establish a global gravity field-related vertical reference system that (1) supports a highly-precise (at cm-level) combination of physical and geometric heights worldwide, (2) allows the unification of all existing local height datums, and (3) guarantees vertical coordinates with global consistency (the same accuracy everywhere) and long-term stability (the same order of accuracy at any time). Under this umbrella, the present contribution concentrates on the definition and realization of a conventional global vertical reference system; the standardization of the geodetic data referring to the existing height systems; and the formulation of appropriate strategies for the precise transformation of the local height datums into the global vertical reference system. The proposed vertical reference system is based on two components: a geometric component consisting of ellipsoidal heights as coordinates and a level ellipsoid as the reference surface, and a physical component comprising geopotential numbers as coordinates and an equipotential surface defined by a conventional W0 value as the reference surface. The definition of the physical component is based on potential parameters in order to provide reference to any type of physical heights (normal, orthometric, etc.). The conversion of geopotential numbers into metric heights and the modelling of the reference surface (geoid or quasigeoid determination) are considered as steps of the realization. The vertical datum unification strategy is based on (1) the physical connection of height datums to determine their discrepancies, (2) joint analysis of satellite altimetry and tide gauge records to determine time variations of sea level at reference tide gauges, (3) combination of geometrical and physical heights in a well-distributed and high-precise reference frame to estimate the relationship between the individual vertical levels and the global one, and (4) analysis of GNSS time series at reference tide gauges to separate crustal movements from sea level changes. The final vertical transformation parameters are provided by the common adjustment of the observation equations derived from these methods.

On an Allan variance approach to classify VLBI radio-sources on the basis of their astrometric stability

NASA Astrophysics Data System (ADS)

Gattano, C.; Lambert, S.; Bizouard, C.

2017-12-01

In the context of selecting sources defining the celestial reference frame, we compute astrometric time series of all VLBI radio-sources from observations in the International VLBI Service database. The time series are then analyzed with Allan variance in order to estimate the astrometric stability. From results, we establish a new classification that takes into account the whole multi-time scales information. The algorithm is flexible on the definition of ``stable source" through an adjustable threshold.

Reference frames, gauge transformations and gravitomagnetism in the post-Newtonian theory of the lunar motion

NASA Astrophysics Data System (ADS)

Xie, Yi; Kopeikin, Sergei

2010-01-01

We construct a set of reference frames for description of the orbital and rotational motion of the Moon. We use a scalar-tensor theory of gravity depending on two parameters of the parametrized post-Newtonian (PPN) formalism and utilize the concepts of the relativistic resolutions on reference frames adopted by the International Astronomical Union in 2000. We assume that the solar system is isolated and space-time is asymptotically flat. The primary reference frame has the origin at the solar-system barycenter (SSB) and spatial axes are going to infinity. The SSB frame is not rotating with respect to distant quasars. The secondary reference frame has the origin at the Earth-Moon barycenter (EMB). The EMB frame is local with its spatial axes spreading out to the orbits of Venus and Mars and not rotating dynamically in the sense that both the Coriolis and centripetal forces acting on a free-falling test particle, moving with respect to the EMB frame, are excluded. Two other local frames, the geocentric (GRF) and the selenocentric (SRF) frames, have the origin at the center of mass of the Earth and Moon respectively. They are both introduced in order to connect the coordinate description of the lunar motion, observer on the Earth, and a retro-reflector on the Moon to the observable quantities which are the proper time and the laser-ranging distance. We solve the gravity field equations and find the metric tensor and the scalar field in all frames. We also derive the post-Newtonian coordinate transformations between the frames and analyze the residual gauge freedom of the solutions of the field equations. We discuss the gravitomagnetic effects in the barycentric equations of the motion of the Moon and argue that they are beyond the current accuracy of lunar laser ranging (LLR) observations.

Satellite Ephemeris Correction via Remote Site Observation for Star Tracker Navigation Performance Improvement

DTIC Science & Technology

2016-03-01

squared RMS root mean squared GCRF Geocentric Celestial Reference Frame xi List of Figures Figure Page 1 Geometry of single observation...RA and DEC in the celestial sphere. The Geocentric Celestial Reference Frame (GCRF) is the standard geocentric frame that measures the RA east in the...Figure 2. Right ascension (α) and declination (δ) in the celestial sphere[6] 7 made between geocentric and topocentric angles. Geocentric is referred to

Establishing a celestial VLBI reference frame. 1: Searching for VLBI sources

NASA Technical Reports Server (NTRS)

Preston, R. A.; Morabito, D. D.; Williams, J. G.; Slade, M. A.; Harris, A. W.; Finley, S. G.; Skjerve, L. J.; Tanida, L.; Spitzmesser, D. J.; Johnson, B.

1978-01-01

The Deep Space Network is currently engaged in establishing a new high-accuracy VLBI celestial reference frame. The present status of the task of finding suitable celestial radio sources for constructing this reference frame is discussed. To date, 564 VLBI sources were detected, with 166 of these lying within 10 deg of the ecliptic plane. The variation of the sky distribution of these sources with source strength is examined.

Assessment of Current Estimates of Global and Regional Mean Sea Level from the TOPEX/Poseidon, Jason-1, and OSTM 17-Year Record

NASA Technical Reports Server (NTRS)

Beckley, Brian D.; Ray, Richard D.; Lemoine, Frank G.; Zelensky, N. P.; Holmes, S. A.; Desal, Shailen D.; Brown, Shannon; Mitchum, G. T.; Jacob, Samuel; Luthcke, Scott B.

2010-01-01

The science value of satellite altimeter observations has grown dramatically over time as enabling models and technologies have increased the value of data acquired on both past and present missions. With the prospect of an observational time series extending into several decades from TOPEX/Poseidon through Jason-1 and the Ocean Surface Topography Mission (OSTM), and further in time with a future set of operational altimeters, researchers are pushing the bounds of current technology and modeling capability in order to monitor global sea level rate at an accuracy of a few tenths of a mm/yr. The measurement of mean sea-level change from satellite altimetry requires an extreme stability of the altimeter measurement system since the signal being measured is at the level of a few mm/yr. This means that the orbit and reference frame within which the altimeter measurements are situated, and the associated altimeter corrections, must be stable and accurate enough to permit a robust MSL estimate. Foremost, orbit quality and consistency are critical to satellite altimeter measurement accuracy. The orbit defines the altimeter reference frame, and orbit error directly affects the altimeter measurement. Orbit error remains a major component in the error budget of all past and present altimeter missions. For example, inconsistencies in the International Terrestrial Reference Frame (ITRF) used to produce the precision orbits at different times cause systematic inconsistencies to appear in the multimission time-frame between TOPEX and Jason-1, and can affect the intermission calibration of these data. In an effort to adhere to cross mission consistency, we have generated the full time series of orbits for TOPEX/Poseidon (TP), Jason-1, and OSTM based on recent improvements in the satellite force models, reference systems, and modeling strategies. The recent release of the entire revised Jason-1 Geophysical Data Records, and recalibration of the microwave radiometer correction also require the further re-examination of inter-mission consistency issues. Here we present an assessment of these recent improvements to the accuracy of the 17 -year sea surface height time series, and evaluate the subsequent impact on global and regional mean sea level estimates.

Overall properties of the Gaia DR1 reference frame

NASA Astrophysics Data System (ADS)

Liu, N.; Zhu, Z.; Liu, J.-C.; Ding, C.-Y.

2017-03-01

Aims: The first Gaia data release (Gaia DR1) provides 2191 ICRF2 sources with their positions in the auxiliary quasar solution and five astrometric parameters - positions, parallaxes, and proper motions - for stars in common between the Tycho-2 catalogue and Gaia in the joint Tycho-Gaia astrometric solution (TGAS). We aim to analyze the overall properties of Gaia DR1 reference frame. Methods: We compare quasar positions of the auxiliary quasar solution with ICRF2 sources using different samples and evaluate the influence on the Gaia DR1 reference frame owing to the Galactic aberration effect over the J2000.0-J2015.0 period. Then we estimate the global rotation between TGAS with Tycho-2 proper motion systems to investigate the property of the Gaia DR1 reference frame. Finally, the Galactic kinematics analysis using the K-M giant proper motions is performed to understand the property of Gaia DR1 reference frame. Results: The positional comparison between the auxiliary quasar solution and ICRF2 shows negligible orientation and validates the declination bias of -0.1mas in Gaia quasar positions with respect to ICRF2. Galactic aberration effect is thought to cause an offset 0.01mas of the Z axis direction of Gaia DR1 reference frame. The global rotation between TGAS and Tycho-2 proper motion systems, obtained by different samples, shows a much smaller value than the claimed value 0.24mas yr-1. For the Galactic kinematics analysis of the TGAS K-M giants, we find possible non-zero Galactic rotation components beyond the classical Oort constants: the rigid part ωYG = -0.38±0.15mas yr-1 and the differential part ω^primeYG = -0.29±0.19mas yr-1 around the YG axis of Galactic coordinates, which indicates possible residual rotation in Gaia DR1 reference frame or problems in the current Galactic kinematical model. Conclusions: The Gaia DR1 reference frame is well aligned to ICRF2, and the possible influence of the Galactic aberration effect should be taken into consideration for the future Gaia-ICRF link. The cause of the rather small global rotation between TGAS and Tycho-2 proper motion systems is unclear and needs further investigation. The possible residual rotation in Gaia DR1 reference frame inferred from the Galactic kinematic analysis should be noted and examined in future data release.

Establishing a Modern Ground Network for Space Geodesy Applications

NASA Technical Reports Server (NTRS)

Pearlman, M.; Pavlis, E.; Altamimi, Z.; Noll, C.

2010-01-01

Ground-based networks of co-located space-geodesy techniques (VLBI, SLR, GLASS, DORIS) are the basis for the development and maintenance of the :International Terrestrial deference Frame (ITRE), which is the basis for our metric measurements of global change. The Global Geodetic Observing System (GGOS) within the International Association of Geodesy has established a task to develop a strategy to design, integrate and maintain the fundamental geodetic network and supporting infrastructure in a sustainable way to satisfy the long-term requirements for the reference frame. The GGOS goal is an origin definition at I mm or better and a temporal stability on the order of 0.1 mm/y, with similar numbers for the scale and orientation components. These goals are based on scientific requirements to address sea level rise with confidence. As a first step, simulations focused on establishing the optimal global SLR and VLBI network, since these two techniques alone are sufficient to define the reference frame. The GLASS constellations will then distribute the reference frame to users anywhere on the Earth. Using simulated data to be collected by the future networks, we investigated various designs and the resulting accuracy in the origin, scale and orientation of the resulting ITRF. We present here the results of extensive simulation studies aimed at designing optimal global geodetic networks to support GGOS science products. Current estimates are the network will require 24 - 32 globally distributed co-location sites. Stations in the near global network will require geologically stable sites witla good weather, established infrastructure, and local support and personnel. EGOS will seek groups that are interested in participation. GGOS intends to issues a Call for Participation of groups that would like to take part in the network implementation and operation_ Some examples of integrated stations currently in operation or under development will be presented. We will examine necessary conditions and challenges in designing a co-location station.

Spatial vision within egocentric and exocentric frames of reference

NASA Technical Reports Server (NTRS)

Howard, Ian P.

1989-01-01

The extent to which perceptual judgements within egocentric and exocentric frames of reference are subject to illusory disturbances and long term modifications is discussed. It is argued that well known spatial illusions, such as the oculogyral illusion and induced visual motion have usually been discussed without proper attention being paid to the frame of reference within which they occur, and that this has led to the construction of inadequate theories and inappropriate procedures for testing them.

Reference frames in virtual spatial navigation are viewpoint dependent

PubMed Central

Török, Ágoston; Nguyen, T. Peter; Kolozsvári, Orsolya; Buchanan, Robert J.; Nadasdy, Zoltan

2014-01-01

Spatial navigation in the mammalian brain relies on a cognitive map of the environment. Such cognitive maps enable us, for example, to take the optimal route from a given location to a known target. The formation of these maps is naturally influenced by our perception of the environment, meaning it is dependent on factors such as our viewpoint and choice of reference frame. Yet, it is unknown how these factors influence the construction of cognitive maps. Here, we evaluated how various combinations of viewpoints and reference frames affect subjects' performance when they navigated in a bounded virtual environment without landmarks. We measured both their path length and time efficiency and found that (1) ground perspective was associated with egocentric frame of reference, (2) aerial perspective was associated with allocentric frame of reference, (3) there was no appreciable performance difference between first and third person egocentric viewing positions and (4) while none of these effects were dependent on gender, males tended to perform better in general. Our study provides evidence that there are inherent associations between visual perspectives and cognitive reference frames. This result has implications about the mechanisms of path integration in the human brain and may also inspire designs of virtual reality applications. Lastly, we demonstrated the effective use of a tablet PC and spatial navigation tasks for studying spatial and cognitive aspects of human memory. PMID:25249956

Reference frames in virtual spatial navigation are viewpoint dependent.

PubMed

Török, Agoston; Nguyen, T Peter; Kolozsvári, Orsolya; Buchanan, Robert J; Nadasdy, Zoltan

2014-01-01

Spatial navigation in the mammalian brain relies on a cognitive map of the environment. Such cognitive maps enable us, for example, to take the optimal route from a given location to a known target. The formation of these maps is naturally influenced by our perception of the environment, meaning it is dependent on factors such as our viewpoint and choice of reference frame. Yet, it is unknown how these factors influence the construction of cognitive maps. Here, we evaluated how various combinations of viewpoints and reference frames affect subjects' performance when they navigated in a bounded virtual environment without landmarks. We measured both their path length and time efficiency and found that (1) ground perspective was associated with egocentric frame of reference, (2) aerial perspective was associated with allocentric frame of reference, (3) there was no appreciable performance difference between first and third person egocentric viewing positions and (4) while none of these effects were dependent on gender, males tended to perform better in general. Our study provides evidence that there are inherent associations between visual perspectives and cognitive reference frames. This result has implications about the mechanisms of path integration in the human brain and may also inspire designs of virtual reality applications. Lastly, we demonstrated the effective use of a tablet PC and spatial navigation tasks for studying spatial and cognitive aspects of human memory.

Light escape cones in local reference frames of Kerr-de Sitter black hole spacetimes and related black hole shadows

NASA Astrophysics Data System (ADS)

Stuchlík, Zdeněk; Charbulák, Daniel; Schee, Jan

2018-03-01

We construct the light escape cones of isotropic spot sources of radiation residing in special classes of reference frames in the Kerr-de Sitter (KdS) black hole spacetimes, namely in the fundamental class of `non-geodesic' locally non-rotating reference frames (LNRFs), and two classes of `geodesic' frames, the radial geodesic frames (RGFs), both falling and escaping, and the frames related to the circular geodesic orbits (CGFs). We compare the cones constructed in a given position for the LNRFs, RGFs, and CGFs. We have shown that the photons locally counter-rotating relative to LNRFs with positive impact parameter and negative covariant energy are confined to the ergosphere region. Finally, we demonstrate that the light escaping cones govern the shadows of black holes located in front of a radiating screen, as seen by the observers in the considered frames. For shadows related to distant static observers the LNRFs are relevant.

Celestial Reference Frames at Multiple Radio Wavelengths

NASA Technical Reports Server (NTRS)

Jacobs, Christopher S.

2012-01-01

In 1997 the IAU adopted the International Celestial Reference Frame (ICRF) built from S/X VLBI data. In response to IAU resolutions encouraging the extension of the ICRF to additional frequency bands, VLBI frames have been made at 24, 32, and 43 gigahertz. Meanwhile, the 8.4 gigahertz work has been greatly improved with the 2009 release of the ICRF-2. This paper discusses the motivations for extending the ICRF to these higher radio bands. Results to date will be summarized including evidence that the high frequency frames are rapidly approaching the accuracy of the 8.4 gigahertz ICRF-2. We discuss current limiting errors and prospects for the future accuracy of radio reference frames. We note that comparison of multiple radio frames is characterizing the frequency dependent systematic noise floor from extended source morphology and core shift. Finally, given Gaia's potential for high accuracy optical astrometry, we have simulated the precision of a radio-optical frame tie to be approximately10-15 microarcseconds ((1-sigma) (1-standard deviation), per component).

New International Agreements About Space Techniques Among Argentina, China and France

NASA Astrophysics Data System (ADS)

Pacheco, A. M.; Podestá, R.; Actis, E.; Adarvez, S.; Quinteros, J.; Li, J.; Saunier, J.; Podestá, F.; Ramos, F.; Aguilera, J.; Sosa, G.; Hauser, D.

2018-01-01

The International Earth Rotation and Reference Systems (IERS) is in charge of defining and materializing celestial reference systems (ICRS - ICRF) and terrestrial reference systems (ITRS - ITRF). In order to perform this task it uses data from the following techniques: Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Navigation Satellite System (GNSS) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS). Nowadays, the Observatorio Astronómico Félix Aguilar (OAFA) has two instruments with these advanced techniques: SLR and a permanent GNSS station. In the nearby future a 40 m diameter radio telescope will be available that will be operated in VLBI mode along with a DORIS buoy which will be co-localized with a SLR telescope and GNSS antennas. In this way OAFA will become a zero station, first class, of the ITRF 2014 frame.

Reprocessing Multiyear GPS Data from Continuously Operating Reference Stations on Cloud Computing Platform

NASA Astrophysics Data System (ADS)

Yoon, S.

2016-12-01

To define geodetic reference frame using GPS data collected by Continuously Operating Reference Stations (CORS) network, historical GPS data needs to be reprocessed regularly. Reprocessing GPS data collected by upto 2000 CORS sites for the last two decades requires a lot of computational resource. At National Geodetic Survey (NGS), there has been one completed reprocessing in 2011, and currently, the second reprocessing is undergoing. For the first reprocessing effort, in-house computing resource was utilized. In the current second reprocessing effort, outsourced cloud computing platform is being utilized. In this presentation, the outline of data processing strategy at NGS is described as well as the effort to parallelize the data processing procedure in order to maximize the benefit of the cloud computing. The time and cost savings realized by utilizing cloud computing approach will also be discussed.

Separability and Entanglement in the Hilbert Space Reference Frames Related Through the Generic Unitary Transform for Four Level System

NASA Astrophysics Data System (ADS)

Man'ko, V. I.; Markovich, L. A.

2018-02-01

Quantum correlations in the state of four-level atom are investigated by using generic unitary transforms of the classical (diagonal) density matrix. Partial cases of pure state, X-state, Werner state are studied in details. The geometrical meaning of unitary Hilbert reference-frame rotations generating entanglement in the initially separable state is discussed. Characteristics of the entanglement in terms of concurrence, entropy and negativity are obtained as functions of the unitary matrix rotating the reference frame.

Superenergy flux of Einstein-Rosen waves

NASA Astrophysics Data System (ADS)

Domínguez, P. J.; Gallegos, A.; Macías-Díaz, J. E.; Vargas-Rodríguez, H.

In this work, we consider the propagation speed of the superenergy flux associated to the Einstein-Rosen cylindrical waves propagating in vacuum and over the background of the gravitational field of an infinitely long mass line distribution. The velocity of the flux is determined considering the reference frame in which the super-Poynting vector vanishes. This reference frame is then considered as comoving with the flux. The explicit expressions for the velocities are given with respect to a reference frame at rest with the symmetry axis.

Characterization of system-related geometric distortions in MR images employed in Gamma Knife radiosurgery applications.

PubMed

Pappas, E P; Seimenis, I; Moutsatsos, A; Georgiou, E; Nomikos, P; Karaiskos, P

2016-10-07

This work provides characterization of system-related geometric distortions present in MRIs used in Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment planning. A custom-made phantom, compatible with the Leksell stereotactic frame model G and encompassing 947 control points (CPs), was utilized. MR images were obtained with and without the frame, thus allowing discrimination of frame-induced distortions. In the absence of the frame and following compensation for field inhomogeneities, measured average CP disposition owing to gradient nonlinearities was 0.53 mm. In presence of the frame, contrarily, detected distortion was greatly increased (up to about 5 mm) in the vicinity of the frame base due to eddy currents induced in the closed loop of its aluminum material. Frame-related distortion was obliterated at approximately 90 mm from the frame base. Although the region with the maximum observed distortion may not lie within the GK treatable volume, the presence of the frame results in distortion of the order of 1.5 mm at a 7 cm distance from the center of the Leksell space. Additionally, severe distortions observed outside the treatable volume could possibly impinge on the delivery accuracy mainly by adversely affecting the registration process (e.g. the position of the lower part of the N-shaped fiducials used to define the stereotactic space may be miss-registered). Images acquired with a modified version of the frame developed by replacing its front side with an acrylic bar, thus interrupting the closed aluminum loop and reducing the induced eddy currents, were shown to benefit from relatively reduced distortion. System-related distortion was also identified in patient MR images. Using corresponding CT angiography images as a reference, an offset of 1.1 mm was detected for two vessels lying in close proximity to the frame base, while excellent spatial agreement was observed for a vessel far apart from the frame base.

Characterization of system-related geometric distortions in MR images employed in Gamma Knife radiosurgery applications

NASA Astrophysics Data System (ADS)

Pappas, E. P.; Seimenis, I.; Moutsatsos, A.; Georgiou, E.; Nomikos, P.; Karaiskos, P.

2016-10-01

This work provides characterization of system-related geometric distortions present in MRIs used in Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment planning. A custom-made phantom, compatible with the Leksell stereotactic frame model G and encompassing 947 control points (CPs), was utilized. MR images were obtained with and without the frame, thus allowing discrimination of frame-induced distortions. In the absence of the frame and following compensation for field inhomogeneities, measured average CP disposition owing to gradient nonlinearities was 0.53 mm. In presence of the frame, contrarily, detected distortion was greatly increased (up to about 5 mm) in the vicinity of the frame base due to eddy currents induced in the closed loop of its aluminum material. Frame-related distortion was obliterated at approximately 90 mm from the frame base. Although the region with the maximum observed distortion may not lie within the GK treatable volume, the presence of the frame results in distortion of the order of 1.5 mm at a 7 cm distance from the center of the Leksell space. Additionally, severe distortions observed outside the treatable volume could possibly impinge on the delivery accuracy mainly by adversely affecting the registration process (e.g. the position of the lower part of the N-shaped fiducials used to define the stereotactic space may be miss-registered). Images acquired with a modified version of the frame developed by replacing its front side with an acrylic bar, thus interrupting the closed aluminum loop and reducing the induced eddy currents, were shown to benefit from relatively reduced distortion. System-related distortion was also identified in patient MR images. Using corresponding CT angiography images as a reference, an offset of 1.1 mm was detected for two vessels lying in close proximity to the frame base, while excellent spatial agreement was observed for a vessel far apart from the frame base.

GENERAL RELATIVITY DERIVATION OF BEAM REST-FRAME HAMILTONIAN.

DOE Office of Scientific and Technical Information (OSTI.GOV)

WEI,J.

2001-06-18

Analysis of particle interaction in the laboratory frame of storage rings is often complicated by the fact that particle motion is relativistic, and that reference particle trajectory is curved. Rest frame of the reference particle is a convenient coordinate system to work with, within which particle motion is non-relativistic. We have derived the equations of motion in the beam rest frame from the general relativity formalism, and have successfully applied them to the analysis of crystalline beams [1].

Assessment of second- and third-order ionospheric effects on regional networks: case study in China with longer CMONOC GPS coordinate time series

NASA Astrophysics Data System (ADS)

Deng, Liansheng; Jiang, Weiping; Li, Zhao; Chen, Hua; Wang, Kaihua; Ma, Yifang

2017-02-01

Higher-order ionospheric (HOI) delays are one of the principal technique-specific error sources in precise global positioning system analysis and have been proposed to become a standard part of precise GPS data processing. In this research, we apply HOI delay corrections to the Crustal Movement Observation Network of China's (CMONOC) data processing (from January 2000 to December 2013) and furnish quantitative results for the effects of HOI on CMONOC coordinate time series. The results for both a regional reference frame and global reference frame are analyzed and compared to clarify the HOI effects on the CMONOC network. We find that HOI corrections can effectively reduce the semi-annual signals in the northern and vertical components. For sites with lower semi-annual amplitudes, the average decrease in magnitude can reach 30 and 10 % for the northern and vertical components, respectively. The noise amplitudes with HOI corrections and those without HOI corrections are not significantly different. Generally, the HOI effects on CMONOC networks in a global reference frame are less obvious than the results in the regional reference frame, probably because the HOI-induced errors are smaller in comparison to the higher noise levels seen when using a global reference frame. Furthermore, we investigate the combined contributions of environmental loading and HOI effects on the CMONOC stations. The largest loading effects on the vertical displacement are found in the mid- to high-latitude areas. The weighted root mean square differences between the corrected and original weekly GPS height time series of the loading model indicate that the mass loading adequately reduced the scatter on the CMONOC height time series, whereas the results in the global reference frame showed better agreements between the GPS coordinate time series and the environmental loading. When combining the effects of environmental loading and HOI corrections, the results with the HOI corrections reduced the scatter on the observed GPS height coordinates better than the height when estimated without HOI corrections, and the combined solutions in the regional reference frame indicate more preferred improvements. Therefore, regional reference frames are recommended to investigate the HOI effects on regional networks.

Hierarchical motion organization in random dot configurations

NASA Technical Reports Server (NTRS)

Bertamini, M.; Proffitt, D. R.; Kaiser, M. K. (Principal Investigator)

2000-01-01

Motion organization has 2 aspects: the extraction of a (moving) frame of reference and the hierarchical organization of moving elements within the reference frame. Using a discrimination of relative motions task, the authors found large differences between different types of motion (translation, divergence, and rotation) in the degree to which each can serve as a moving frame of reference. Translation and divergence are superior to rotation. There are, however, situations in which rotation can serve as a reference frame. This is due to the presence of a second factor, structural invariants (SIs). SIs are spatial relationships persisting among the elements within a configuration such as a collinearity among points or one point coinciding with the center of rotation for another (invariant radius). The combined effect of these 2 factors--motion type and SIs-influences perceptual motion organization.

A spatial reference frame model of Beijing based on spatial cognitive experiment

NASA Astrophysics Data System (ADS)

Zhang, Jie; Zhang, Jing; Liu, Yu

2006-10-01

Orientation relation in the spatial relation is very important in GIS. People can obtain orientation information by making use of map reading and the cognition of the surrounding environment, and then create the spatial reference frame. City is a kind of special spatial environment, a person with life experiences has some spatial knowledge about the city where he or she lives in. Based on the spatial knowledge of the city environment, people can position, navigate and understand the meaning embodied in the environment correctly. Beijing as a real geographic space, its layout is very special and can form a kind of new spatial reference frame. Based on the characteristics of the layout of Beijing city, this paper will introduce a new spatial reference frame of Beijing and use two psychological experiments to validate its cognitive plausibility.

Description and User Instructions for the Quaternion_to_Orbit_v3 Software

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry V.; Kruizinga, Gerhard L.; Paik, Meegyeong; Yuan, Dah-Ning; Asmar, Sami W.

2012-01-01

For a given inertial frame of reference, the software combines the spacecraft orbits with the spacecraft attitude quaternions, and rotates the body-fixed reference frame of a particular spacecraft to the inertial reference frame. The conversion assumes that the two spacecraft are aligned with respect to the mutual line of sight, with a parameterized time tag. The software is implemented in Python and is completely open source. It is very versatile, and may be applied under various circumstances and for other related purposes. Based on the solid linear algebra analysis, it has an extra option for compensating the linear pitch. This software has been designed for simulation of the calibration maneuvers performed by the two spacecraft comprising the GRAIL mission to the Moon, but has potential use for other applications. In simulations of formation flights, one needs to coordinate the spacecraft orbits represented in an appropriate inertial reference frame and the spacecraft attitudes. The latter are usually given as the time series of quaternions rotating the body-fixed reference frame of a particular spacecraft to the inertial reference frame. It is often desirable to simulate the same maneuver for different segments of the orbit. It is also useful to study various maneuvers that could be performed at the same orbit segment. These two lines of study are more timeand labor-efficient if the attitude and orbit data are generated independently, so that the part of the data that has not been changed can be recycled in the course of multiple simulations.

``Frames of Reference'' revisited

NASA Astrophysics Data System (ADS)

Steyn-Ross, Alistair; Ivey, Donald G.

1992-12-01

The PSSC teaching film, ``Frames of Reference,'' was made in 1960, and was one of the first audio-visual attempts at showing how your physical ``point of view,'' or frame of reference, necessarily alters both your perceptions and your observations of motion. The gentle humor and original demonstrations made a lasting impact on many audiences, and with its recent re-release as part of the AAPT Cinema Classics videodisc it is timely that we should review both the message and the methods of the film. An annotated script and photographs from the film are presented, followed by extension material on rotating frames which teachers may find appropriate for use in their classrooms: constructions, demonstrations, an example, and theory.

Directional responding of C57BL/6J mice in the Morris water maze is influenced by visual and vestibular cues and is dependent upon the anterior thalamic nuclei

PubMed Central

Stackman, Robert W.; Lora, Joan C.; Williams, Sidney B.

2012-01-01

Recent findings indicate that rats navigate in spatial tasks such as the Morris water maze (MWM) using a local cue-based reference frame rather than a distal cue-based reference frame. Specifically, rats swim in a particular direction to a location relative to pool-based cues, rather than to an absolute location defined by room-based cues. Neural mechanisms supporting this bias in rodents for relative responding in spatial tasks are not yet understood. Anterior thalamic neurons discharge according to the current directional heading of the animal. The contribution of head direction (HD) cell activity to navigation has been difficult to elucidate. We found that male C57BL/6J mice trained for 4 or 7 days in the MWM exhibited an overwhelming preference for swimming in a direction relative to pool-based cues over absolute responding during a platform-less probe test. Rotation of extra-maze cues caused a corresponding rotation of the direction mice swam during probe test, suggesting that both pool- and room-based reference frames guide platform search. However, disorienting the mice before the probe test disturbed relative responding. Therefore, relative responding is guided by both internal and external cue sources. Selective inactivation of anterior thalamic nuclei (ATN) by microinfusion of muscimol or fluorophore-conjugated muscimol caused a near complete shift in preference from relative to absolute responding. Interestingly, inactivation of the dorsal CA1 region of the hippocampus did not affect relative responding. These data suggest that ATN, and HD cells therein, may guide relative responding in the MWM, a task considered by most to reflect hippocampal processing. PMID:22836256

Use of Reference Frames for Interplanetary Navigation at JPL

NASA Technical Reports Server (NTRS)

Heflin, Michael; Jacobs, Chris; Sovers, Ojars; Moore, Angelyn; Owen, Sue

2010-01-01

Navigation of interplanetary spacecraft is typically based on range, Doppler, and differential interferometric measurements made by ground-based telescopes. Acquisition and interpretation of these observations requires accurate knowledge of the terrestrial reference frame and its orientation with respect to the celestial frame. Work is underway at JPL to reprocess historical VLBI and GPS data to improve realizations of the terrestrial and celestial frames. Improvements include minimal constraint alignment, improved tropospheric modeling, better orbit determination, and corrections for antenna phase center patterns.

Space Operations Center, shuttle interaction study, volume 1

NASA Technical Reports Server (NTRS)

1981-01-01

The feasibility of the shuttle remote manipulator system (SRMS)-aided space operations center (SOC)/orbiter berthing was evaluated to determine: (1) whether the initial rates between the SOC and the orbiter can be removed by the arm; (2) what is the best strategy to be used; (3) whether the post-capture and maneuvering loads are within the capability of the SRMS; (4) can the SOC berthing port be brought in the immediate proximity of the orbiter berthing port; and (5) what is the best way to remove the residual relative motions. Various notational conventions are established and various important locations on the orbiter and SOC structures are defined. Reference frames are defined together with the mass properties of both the SOC and the orbiter.

To frame is to explain: a deductive frame-analysis of Dutch and French climate change coverage during the annual UN Conferences of the Parties.

PubMed

Dirikx, Astrid; Gelders, Dave

2010-11-01

This study examines the way Dutch and French newspapers frame climate change during the annual United Nations Conferences of the Parties. The methods used in previous studies on the framing of climate change do not allow for general cross-national comparisons. We conduct a quantitative deductive framing analysis on 257 quality Dutch and French newspaper articles between 2001 and 2007. Both countries' newspapers seem to frame climate change through mainly the same lens. The majority of the articles make reference to the consequences of the (non-)pursuit of a certain course of action and of possible losses and gains (consequences frame). Additionally, many articles mention the need for urgent actions, refer to possible solutions and suggest that governments are responsible for and/or capable of alleviating climate change problems (responsibility frame). Finally, the conflict frame was found to be used less often than the aforementioned frames, but more regularly than the human interest frame.

Cultural background shapes spatial reference frame proclivity

PubMed Central

Goeke, Caspar; Kornpetpanee, Suchada; Köster, Moritz; Fernández-Revelles, Andrés B.; Gramann, Klaus; König, Peter

2015-01-01

Spatial navigation is an essential human skill that is influenced by several factors. The present study investigates how gender, age, and cultural background account for differences in reference frame proclivity and performance in a virtual navigation task. Using an online navigation study, we recorded reaction times, error rates (confusion of turning axis), and reference frame proclivity (egocentric vs. allocentric reference frame) of 1823 participants. Reaction times significantly varied with gender and age, but were only marginally influenced by the cultural background of participants. Error rates were in line with these results and exhibited a significant influence of gender and culture, but not age. Participants’ cultural background significantly influenced reference frame selection; the majority of North-Americans preferred an allocentric strategy, while Latin-Americans preferred an egocentric navigation strategy. European and Asian groups were in between these two extremes. Neither the factor of age nor the factor of gender had a direct impact on participants’ navigation strategies. The strong effects of cultural background on navigation strategies without the influence of gender or age underlines the importance of socialized spatial cognitive processes and argues for socio-economic analysis in studies investigating human navigation. PMID:26073656

The Benslimane's Artistic Model for Females' Gaze Beauty: An Original Assessment Tool.

PubMed

Benslimane, Fahd; van Harpen, Laura; Myers, Simon R; Ingallina, Fabio; Ghanem, Ali M

2017-02-01

The aim of this paper is to analyze the aesthetic characteristics of the human females' gaze using anthropometry and to present an artistic model to represent it: "The Frame Concept." In this model, the eye fissure represents a painting, and the most peripheral shadows around it represent the frame of this painting. The narrower the frame, the more aesthetically pleasing and youthful the gaze appears. This study included a literature review of the features that make the gaze appear attractive. Photographs of models with attractive gazes were examined, and old photographs of patients were compared to recent photographs. The frame ratio was defined by anthropometric measurements of modern portraits of twenty consecutive Miss World winners. The concept was then validated for age and attractiveness across centuries by analysis of modern female photographs and works of art acknowledged for portraying beautiful young and older women in classical paintings. The frame height inversely correlated with attractiveness in modern female portrait photographs. The eye fissure frame ratio of modern idealized female portraits was similar to that of beautiful female portraits idealized by classical artists. In contrast, the eye fissure frames of classical artists' mothers' portraits were significantly wider than those of beautiful younger women. The Frame Concept is a valid artistic tool that provides an understanding of both the aesthetic and aging characteristics of the female periorbital region, enabling the practitioner to plan appropriate aesthetic interventions. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the A3 online Instructions to Authors. www.springer.com/00266 .

Language and spatial frames of reference in mind and brain.

PubMed

Gallistel, C R.

2002-08-01

Some language communities routinely use allocentric reference directions (e.g. 'uphill-downhill') where speakers of European languages would use egocentric references ('left-right'). Previous experiments have suggested that the different language groups use different reference frames in non-linguistic tasks involving the recreation of oriented arrays. However, a recent paper argues that manipulating test conditions produces similar effects in monolingual English speakers, and in animals.

Joint Transform Correlation for face tracking: elderly fall detection application

NASA Astrophysics Data System (ADS)

Katz, Philippe; Aron, Michael; Alfalou, Ayman

2013-03-01

In this paper, an iterative tracking algorithm based on a non-linear JTC (Joint Transform Correlator) architecture and enhanced by a digital image processing method is proposed and validated. This algorithm is based on the computation of a correlation plane where the reference image is updated at each frame. For that purpose, we use the JTC technique in real time to track a patient (target image) in a room fitted with a video camera. The correlation plane is used to localize the target image in the current video frame (frame i). Then, the reference image to be exploited in the next frame (frame i+1) is updated according to the previous one (frame i). In an effort to validate our algorithm, our work is divided into two parts: (i) a large study based on different sequences with several situations and different JTC parameters is achieved in order to quantify their effects on the tracking performances (decimation, non-linearity coefficient, size of the correlation plane, size of the region of interest...). (ii) the tracking algorithm is integrated into an application of elderly fall detection. The first reference image is a face detected by means of Haar descriptors, and then localized into the new video image thanks to our tracking method. In order to avoid a bad update of the reference frame, a method based on a comparison of image intensity histograms is proposed and integrated in our algorithm. This step ensures a robust tracking of the reference frame. This article focuses on face tracking step optimisation and evalutation. A supplementary step of fall detection, based on vertical acceleration and position, will be added and studied in further work.

Eckart frame vibration-rotation Hamiltonians: Contravariant metric tensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pesonen, Janne, E-mail: janne.pesonen@helsinki.fi

2014-02-21

Eckart frame is a unique embedding in the theory of molecular vibrations and rotations. It is defined by the condition that the Coriolis coupling of the reference structure of the molecule is zero for every choice of the shape coordinates. It is far from trivial to set up Eckart kinetic energy operators (KEOs), when the shape of the molecule is described by curvilinear coordinates. In order to obtain the KEO, one needs to set up the corresponding contravariant metric tensor. Here, I derive explicitly the Eckart frame rotational measuring vectors. Their inner products with themselves give the rotational elements, andmore » their inner products with the vibrational measuring vectors (which, in the absence of constraints, are the mass-weighted gradients of the shape coordinates) give the Coriolis elements of the contravariant metric tensor. The vibrational elements are given as the inner products of the vibrational measuring vectors with themselves, and these elements do not depend on the choice of the body-frame. The present approach has the advantage that it does not depend on any particular choice of the shape coordinates, but it can be used in conjunction with all shape coordinates. Furthermore, it does not involve evaluation of covariant metric tensors, chain rules of derivation, or numerical differentiation, and it can be easily modified if there are constraints on the shape of the molecule. Both the planar and non-planar reference structures are accounted for. The present method is particular suitable for numerical work. Its computational implementation is outlined in an example, where I discuss how to evaluate vibration-rotation energies and eigenfunctions of a general N-atomic molecule, the shape of which is described by a set of local polyspherical coordinates.« less

Testing the speed of 'spooky action at a distance'.

PubMed

Salart, Daniel; Baas, Augustin; Branciard, Cyril; Gisin, Nicolas; Zbinden, Hugo

2008-08-14

Correlations are generally described by one of two mechanisms: either a first event influences a second one by sending information encoded in bosons or other physical carriers, or the correlated events have some common causes in their shared history. Quantum physics predicts an entirely different kind of cause for some correlations, named entanglement. This reveals itself in correlations that violate Bell inequalities (implying that they cannot be described by common causes) between space-like separated events (implying that they cannot be described by classical communication). Many Bell tests have been performed, and loopholes related to locality and detection have been closed in several independent experiments. It is still possible that a first event could influence a second, but the speed of this hypothetical influence (Einstein's 'spooky action at a distance') would need to be defined in some universal privileged reference frame and be greater than the speed of light. Here we put stringent experimental bounds on the speed of all such hypothetical influences. We performed a Bell test over more than 24 hours between two villages separated by 18 km and approximately east-west oriented, with the source located precisely in the middle. We continuously observed two-photon interferences well above the Bell inequality threshold. Taking advantage of the Earth's rotation, the configuration of our experiment allowed us to determine, for any hypothetically privileged frame, a lower bound for the speed of the influence. For example, if such a privileged reference frame exists and is such that the Earth's speed in this frame is less than 10(-3) times that of the speed of light, then the speed of the influence would have to exceed that of light by at least four orders of magnitude.

Examining reference frame interaction in spatial memory using a distribution analysis.

PubMed

Street, Whitney N; Wang, Ranxiao Frances

2016-02-01

Previous research showed competition among reference frames in spatial attention and language. The present studies developed a new distribution analysis to examine reference frame interactions in spatial memory. Participants viewed virtual arrays of colored pegs and were instructed to remember them either from their own perspective or from the perspective aligned with the rectangular floor. Then they made judgments of relative directions from their respective encoding orientation. Those taking the floor-axis perspective showed systematic bias in the signed errors toward their egocentric perspective, while those taking their own perspective showed no systematic bias, both for random and symmetrical object arrays. The bias toward the egocentric perspective was observed when learning a real symmetric regular object array with strong environmental cues for the aligned axis. These results indicate automatic processing of the self reference while taking the floor-axis perspective but not vice versa, and suggest that research on spatial memory needs to consider the implications of competition effects in reference frame use.

Technical Note: Modification of the standard gain correction algorithm to compensate for the number of used reference flat frames in detector performance studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konstantinidis, Anastasios C.; Olivo, Alessandro; Speller, Robert D.

2011-12-15

Purpose: The x-ray performance evaluation of digital x-ray detectors is based on the calculation of the modulation transfer function (MTF), the noise power spectrum (NPS), and the resultant detective quantum efficiency (DQE). The flat images used for the extraction of the NPS should not contain any fixed pattern noise (FPN) to avoid contamination from nonstochastic processes. The ''gold standard'' method used for the reduction of the FPN (i.e., the different gain between pixels) in linear x-ray detectors is based on normalization with an average reference flat-field. However, the noise in the corrected image depends on the number of flat framesmore » used for the average flat image. The aim of this study is to modify the standard gain correction algorithm to make it independent on the used reference flat frames. Methods: Many publications suggest the use of 10-16 reference flat frames, while other studies use higher numbers (e.g., 48 frames) to reduce the propagated noise from the average flat image. This study quantifies experimentally the effect of the number of used reference flat frames on the NPS and DQE values and appropriately modifies the gain correction algorithm to compensate for this effect. Results: It is shown that using the suggested gain correction algorithm a minimum number of reference flat frames (i.e., down to one frame) can be used to eliminate the FPN from the raw flat image. This saves computer memory and time during the x-ray performance evaluation. Conclusions: The authors show that the method presented in the study (a) leads to the maximum DQE value that one would have by using the conventional method and very large number of frames and (b) has been compared to an independent gain correction method based on the subtraction of flat-field images, leading to identical DQE values. They believe this provides robust validation of the proposed method.« less

Laser Digital Cinema

NASA Astrophysics Data System (ADS)

Takeuchi, Eric B.; Flint, Graham W.; Bergstedt, Robert; Solone, Paul J.; Lee, Dicky; Moulton, Peter F.

2001-03-01

Electronic cinema projectors are being developed that use a digital micromirror device (DMDTM) to produce the image. Photera Technologies has developed a new architecture that produces truly digital imagery using discrete pulse trains of red, green, and blue light in combination with a DMDTM where in the number of pulses that are delivered to the screen during a given frame can be defined in a purely digital fashion. To achieve this, a pulsed RGB laser technology pioneered by Q-Peak is combined with a novel projection architecture that we refer to as Laser Digital CameraTM. This architecture provides imagery wherein, during the time interval of each frame, individual pixels on the screen receive between zero and 255 discrete pulses of each color; a circumstance which yields 24-bit color. Greater color depth, or increased frame rate is achievable by increasing the pulse rate of the laser. Additionally, in the context of multi-screen theaters, a similar architecture permits our synchronously pulsed RGB source to simultaneously power three screens in a color sequential manner; thereby providing an efficient use of photons, together with the simplifications which derive from using a single DMDTM chip in each projector.

Ray Effect Mitigation Through Reference Frame Rotation

DOE PAGES

Tencer, John

2016-05-01

The discrete ordinates method is a popular and versatile technique for solving the radiative transport equation, a major drawback of which is the presence of ray effects. Mitigation of ray effects can yield significantly more accurate results and enhanced numerical stability for combined mode codes. Moreover, when ray effects are present, the solution is seen to be highly dependent upon the relative orientation of the geometry and the global reference frame. It is an undesirable property. A novel ray effect mitigation technique of averaging the computed solution for various reference frame orientations is proposed.

Coordinate references for the indoor/outdoor seamless positioning

NASA Astrophysics Data System (ADS)

Ruan, Ling; Zhang, Ling; Long, Yi; Cheng, Fei

2018-05-01

Indoor positioning technologies are being developed rapidly, and seamless positioning which connected indoor and outdoor space is a new trend. The indoor and outdoor positioning are not applying the same coordinate system and different indoor positioning scenes uses different indoor local coordinate reference systems. A specific and unified coordinate reference frame is needed as the space basis and premise in seamless positioning application. Trajectory analysis of indoor and outdoor integration also requires a uniform coordinate reference. However, the coordinate reference frame in seamless positioning which can applied to various complex scenarios is lacking of research for a long time. In this paper, we proposed a universal coordinate reference frame in indoor/outdoor seamless positioning. The research focus on analysis and classify the indoor positioning scenes and put forward the coordinate reference system establishment and coordinate transformation methods in each scene. And, through some experiments, the calibration method feasibility was verified.

Recycling-oriented characterization of plastic frames and printed circuit boards from mobile phones by electronic and chemical imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmieri, Roberta; Bonifazi, Giuseppe; Serranti, Silvia, E-mail: silvia.serranti@uniroma1.it

Highlights: • A recycling oriented characterization of end-of-life mobile phones was carried out. • Characterization was developed in a zero-waste-perspective, aiming to recover all the mobile phone materials. • Plastic frames and printed circuit boards were analyzed by electronic and chemical imaging. • Suitable milling/classification strategies were set up to define specialized-pre-concentrated-streams. • The proposed approach can improve the recovery of polymers, base/precious metals, rare earths and critical raw materials. - Abstract: This study characterizes the composition of plastic frames and printed circuit boards from end-of-life mobile phones. This knowledge may help define an optimal processing strategy for using thesemore » items as potential raw materials. Correct handling of such a waste is essential for its further “sustainable” recovery, especially to maximize the extraction of base, rare and precious metals, minimizing the environmental impact of the entire process chain. A combination of electronic and chemical imaging techniques was thus examined, applied and critically evaluated in order to optimize the processing, through the identification and the topological assessment of the materials of interest and their quantitative distribution. To reach this goal, end-of-life mobile phone derived wastes have been systematically characterized adopting both “traditional” (e.g. scanning electronic microscopy combined with microanalysis and Raman spectroscopy) and innovative (e.g. hyperspectral imaging in short wave infrared field) techniques, with reference to frames and printed circuit boards. Results showed as the combination of both the approaches (i.e. traditional and classical) could dramatically improve recycling strategies set up, as well as final products recovery.« less

NChina16: A stable geodetic reference frame for geological hazard studies in north China

NASA Astrophysics Data System (ADS)

Wang, G.; Yan, B.; Gan, W.; Geng, J.

2017-12-01

This study established a stable North China Reference Frame 2016 (NChina16) using five years of continuous GPS observations (2011.8 to 2016.8) from 12 continuously operating reference stations (CORS) fixed to the stable interior of the North China Craton. Applications of NChina16 in landslide, subsidence, and post-seismic displacement studies are illustrated. The primary result of this study is the seven parameters for transforming Cartesian ECEF (Earth-Centered, Earth-Fixed) coordinates X, Y, and Z from the International GNSS Service Reference Frame 2008 (IGS08) to NChina16. The seven parameters include the epoch that is used to tie the regional reference frame to IGS08 and the time derivatives of three translations and three rotations. A method for developing a regional geodetic reference frame is introduced in detail. The GIPSY-OASIS (V6.4) software package was used to obtain the precise point positioning (PPP) time series with respect to IGS08. The stability (accuracy) of NChina16 is about 0.5 mm/year in both vertical and horizontal directions. This study also developed a regional seasonal model for correcting vertical displacement time series data derived from the PPP solutions. Long-term GPS observations (1999-2016) from five CORS in north China were used to develop the seasonal model. According to this study, the PPP daily solutions with respect to NChina16 could achieve 2-3 mm horizontal accuracy and 4-5 mm vertical accuracy after being modified by the regional model. NChina16 will be critical to the long-term landslide, subsidence, fault, and structural monitoring in north China and for ongoing post-seismic crustal deformation studies in Japan. NChina16 will be incrementally improved and synchronized with the IGS reference frame update.

The Extended HANDS Characterization and Analysis of Metric Biases

NASA Astrophysics Data System (ADS)

Kelecy, T.; Knox, R.; Cognion, R.

The Extended High Accuracy Network Determination System (Extended HANDS) consists of a network of low cost, high accuracy optical telescopes designed to support space surveillance and development of space object characterization technologies. Comprising off-the-shelf components, the telescopes are designed to provide sub arc-second astrometric accuracy. The design and analysis team are in the process of characterizing the system through development of an error allocation tree whose assessment is supported by simulation, data analysis, and calibration tests. The metric calibration process has revealed 1-2 arc-second biases in the right ascension and declination measurements of reference satellite position, and these have been observed to have fairly distinct characteristics that appear to have some dependence on orbit geometry and tracking rates. The work presented here outlines error models developed to aid in development of the system error budget, and examines characteristic errors (biases, time dependence, etc.) that might be present in each of the relevant system elements used in the data collection and processing, including the metric calibration processing. The relevant reference frames are identified, and include the sensor (CCD camera) reference frame, Earth-fixed topocentric frame, topocentric inertial reference frame, and the geocentric inertial reference frame. The errors modeled in each of these reference frames, when mapped into the topocentric inertial measurement frame, reveal how errors might manifest themselves through the calibration process. The error analysis results that are presented use satellite-sensor geometries taken from periods where actual measurements were collected, and reveal how modeled errors manifest themselves over those specific time periods. These results are compared to the real calibration metric data (right ascension and declination residuals), and sources of the bias are hypothesized. In turn, the actual right ascension and declination calibration residuals are also mapped to other relevant reference frames in an attempt to validate the source of the bias errors. These results will serve as the basis for more focused investigation into specific components embedded in the system and system processes that might contain the source of the observed biases.

Influences of indigenous language on spatial frames of reference in Aboriginal English

NASA Astrophysics Data System (ADS)

Edmonds-Wathen, Cris

2014-06-01

The Aboriginal English spoken by Indigenous children in remote communities in the Northern Territory of Australia is influenced by the home languages spoken by themselves and their families. This affects uses of spatial terms used in mathematics such as `in front' and `behind.' Speakers of the endangered Indigenous Australian language Iwaidja use the intrinsic frame of reference in contexts where speakers of Standard Australian English use the relative frame of reference. Children speaking Aboriginal English show patterns of use that parallel the Iwaidja contexts. This paper presents detailed examples of spatial descriptions in Iwaidja and Aboriginal English that demonstrate the parallel patterns of use. The data comes from a study that investigated how an understanding of spatial frame of reference in Iwaidja could assist teaching mathematics to Indigenous language-speaking students. Implications for teaching mathematics are explored for teachers without previous experience in a remote Indigenous community.

Change of reference frame for tactile localization during child development.

PubMed

Pagel, Birthe; Heed, Tobias; Röder, Brigitte

2009-11-01

Temporal order judgements (TOJ) for two tactile stimuli, one presented to the left and one to the right hand, are less precise when the hands are crossed over the midline than when the hands are uncrossed. This 'crossed hand' effect has been considered as evidence for a remapping of tactile input into an external reference frame. Since late, but not early, blind individuals show such remapping, it has been hypothesized that the use of an external reference frame develops during childhood. Five- to 10-year-old children were therefore tested with the tactile TOJ task, both with uncrossed and crossed hands. Overall performance in the TOJ task improved with age. While children older than 5 1/2 years displayed a crossed hand effect, younger children did not. Therefore the use of an external reference frame for tactile, and possibly multisensory, localization seems to be acquired at age 5.

Spatial Reorientation of Sensorimotor Balance Control in Altered Gravity

NASA Technical Reports Server (NTRS)

Paloski, W. H.; Black, F. L.; Kaufman, G. D.; Reschke, M. F.; Wood, S. J.

2007-01-01

Sensorimotor coordination of body segments following space flight are more pronounced after landing when the head is actively tilted with respect to the trunk. This suggests that central vestibular processing shifts from a gravitational frame of reference to a head frame of reference in microgravity. A major effect of such changes is a significant postural instability documented by standard head-erect Sensory Organization Tests. Decrements in functional performance may still be underestimated when head and gravity reference frames remained aligned. The purpose of this study was to examine adaptive changes in spatial processing for balance control following space flight by incorporating static and dynamic tilts that dissociate head and gravity reference frames. A second aim of this study was to examine the feasibility of altering the re-adaptation process following space flight by providing discordant visual-vestibular-somatosensory stimuli using short-radius pitch centrifugation.

Can Newton's Third Law Be "Derived" from the Second?

NASA Astrophysics Data System (ADS)

Gangopadhyaya, Asim; Harrington, James

2017-04-01

Newton's laws have engendered much discussion over several centuries. Today, the internet is awash with a plethora of information on this topic. We find many references to Newton's laws, often discussions of various types of misunderstandings and ways to explain them. Here we present an intriguing example that shows an assumption hidden in Newton's third law that is often overlooked. As is well known, the first law defines an inertial frame of reference and the second law determines the acceleration of a particle in such a frame due to an external force. The third law describes forces exerted on each other in a two-particle system, and allows us to extend the second law to a system of particles. Students are often taught that the three laws are independent. Here we present an example that challenges this assumption. At first glance, it seems to show that, at least for a special case, the third law follows from the second law. However, a careful examination of the assumptions demonstrates that is not quite the case. Ultimately, the example does illustrate the significance of the concept of mass in linking Newton's dynamical principles.

Frames of Reference in the Classroom

NASA Astrophysics Data System (ADS)

Grossman, Joshua

2012-12-01

The classic film "Frames of Reference"1,2 effectively illustrates concepts involved with inertial and non-inertial reference frames. In it, Donald G. Ivey and Patterson Hume use the cameras perspective to allow the viewer to see motion in reference frames translating with a constant velocity, translating while accelerating, and rotating—all with respect to the Earth frame. The film is a classic for good reason, but today it does have a couple of drawbacks: 1) The film by nature only accommodates passive learning. It does not give students the opportunity to try any of the experiments themselves. 2) The dated style of the 50-year-old film can distract students from the physics content. I present here a simple setup that can recreate many of the movies demonstrations in the classroom. The demonstrations can be used to supplement the movie or in its place, if desired. All of the materials except perhaps the inexpensive web camera should likely be available already in most teaching laboratories. Unlike previously described activities, these experiments do not require travel to another location3 or an involved setup.4,5

Effect of gravito-inertial cues on the coding of orientation in pre-attentive vision.

PubMed

Stivalet, P; Marendaz, C; Barraclough, L; Mourareau, C

1995-01-01

To see if the spatial reference frame used by pre-attentive vision is specified in a retino-centered frame or in a reference frame integrating visual and nonvisual information (vestibular and somatosensory), subjects were centrifuged in a non-pendular cabin and were asked to search for a target distinguishable from distractors by difference in orientation (Treisman's "pop-out" paradigm [1]). In a control condition, in which subjects were sitting immobilized but not centrifuged, this task gave an asymmetric search pattern: Search was rapid and pre-attentional except when the target was aligned with the horizontal retinal/head axis, in which case search was slow and attentional (2). Results using a centrifuge showed that slow/serial search patterns were obtained when the target was aligned with the subjective horizontal axis (and not with the horizontal retinal/head axis). These data suggest that a multisensory reference frame is used in pre-attentive vision. The results are interpreted in terms of Riccio and Stoffregen's "ecological theory" of orientation in which the vertical and horizontal axes constitute independent reference frames (3).

Reference-Frame-Independent and Measurement-Device-Independent Quantum Key Distribution Using One Single Source

NASA Astrophysics Data System (ADS)

Li, Qian; Zhu, Changhua; Ma, Shuquan; Wei, Kejin; Pei, Changxing

2018-04-01

Measurement-device-independent quantum key distribution (MDI-QKD) is immune to all detector side-channel attacks. However, practical implementations of MDI-QKD, which require two-photon interferences from separated independent single-photon sources and a nontrivial reference alignment procedure, are still challenging with current technologies. Here, we propose a scheme that significantly reduces the experimental complexity of two-photon interferences and eliminates reference frame alignment by the combination of plug-and-play and reference frame independent MDI-QKD. Simulation results show that the secure communication distance can be up to 219 km in the finite-data case and the scheme has good potential for practical MDI-QKD systems.

Electromagnetic pulse scattering by a wedge moving in a free space with relativistic velocity

NASA Astrophysics Data System (ADS)

Ciarkowski, Adam

Recently, increased interest is observed in studying scattering of electromagnetic signals by objects moving with large velocities. The velocities considered can attain relativistic values. Interesting phenomena characteristic of this class of problems were observed, in this number the Doppler shift of equiphase surfaces in the diffracted wave. Apart from new techniques elaborated to attack general scattering problems involving moving objects, specific scaterring problems are also examined. Of special interest are moving scatterers with edges. The simplest scaterrer with this property is a wedge, which in particular case reduces to a half-plane. There is a number of recent works in which diffraction of specific electromagnetic signals by these objects in motion are analyzed. In most cases time-harmonic excitation fields are being assumed. This contribution is concerned with the analysis of 2D scattering of an electromagnetic pulse by a perfectly conducting wedge moving in a free space with relativistic velocity. The exciting field is a pulsed plane-wave signal, with its envelope described by a Dirac delta function. This choice is motivated by the fact that solutions to excitation fields with different envelopes can be obtained from that found here by its integration with an appropriate weight function. In this sense this solution plays a role of a Green function. In our analysis we neglect any dispersion phenomena connected with the surrounding medium. The results herein obtained may be useful in modelling phenomena connected with the space technology. In our analysis we apply the Frame Hopping Method. In particular we first Lorentz transform the pulse signal from the laboratory frame of reference where this field is defined, to the frame where the wedge is at rest. In the latter frame we Fourier transform the resulting field to the complex frequency domain, thus arriving at the problem of time-harmonic diffraction by the wedge at rest. This problem has the exact solution, found yet by Sommerfeld. We take advantage of this solution and transform it back from complex frequency to the time domain. In this transformation both inverse Fourier transform and Felsen technique are used. Finally, the transient field obtained in the moving frame of reference is Lorentz transformed to the laboratory frame. We carry our calculations for both E- and H-field polarizations and show that the field distribution in the laboratory frame is not simply a moving image of that in the moving frame. For wedge velocities much lower than the velocity of light we reduce general expressions for the field in this frame to simpler ones.

Connecting kinematic and dynamic reference frames by D-VLBI

NASA Astrophysics Data System (ADS)

Schuh, Harald; Plank, Lucia; Madzak, Matthias; Böhm, Johannes

2012-08-01

In geodetic and astrometric practice, terrestrial station coordinates are usually provided in the kinematic International Terrestrial Reference Frame (ITRF) and radio source coordinates in the International Celestial Reference Frame (ICRF), whereas measurements of space probes such as satellites and spacecrafts, or planetary ephemerides rest upon dynamical theories. To avoid inconsistencies and errors during measurement and calculation procedures, exact frame ties between quasi - inertial, kinematic and dynamic reference frames have to be secured. While the Earth Orientation Parameters (EOP), e.g. measured by VLBI, link the ITRF to the ICRF, the ties with the dynamic frames can be established with the differential Very Long Baseline Interferometry (D - VLBI) method. By observing space probes alternately t o radio sources, the relative position of the targets to each other on the sky can be determined with high accuracy. While D - VLBI is a common technique in astrophysics (source imaging) and deep space navigation, just recently there have been several effort s to use it for geodetic purposes. We present investigations concerning possible VLBI observations to satellites. This includes the potential usage of available GNNS satellites as well as specifically designed missions, as e.g. the GRASP mission proposed b y JPL/NASA and an international consortium, where the aspect of co - location in space of various techniques (VLBI, SLR, GNSS, DORIS) is the main focus.

Parallel updating and weighting of multiple spatial maps for visual stability during whole body motion

PubMed Central

Medendorp, W. P.

2015-01-01

It is known that the brain uses multiple reference frames to code spatial information, including eye-centered and body-centered frames. When we move our body in space, these internal representations are no longer in register with external space, unless they are actively updated. Whether the brain updates multiple spatial representations in parallel, or whether it restricts its updating mechanisms to a single reference frame from which other representations are constructed, remains an open question. We developed an optimal integration model to simulate the updating of visual space across body motion in multiple or single reference frames. To test this model, we designed an experiment in which participants had to remember the location of a briefly presented target while being translated sideways. The behavioral responses were in agreement with a model that uses a combination of eye- and body-centered representations, weighted according to the reliability in which the target location is stored and updated in each reference frame. Our findings suggest that the brain simultaneously updates multiple spatial representations across body motion. Because both representations are kept in sync, they can be optimally combined to provide a more precise estimate of visual locations in space than based on single-frame updating mechanisms. PMID:26490289

Frame by Frame II: A Filmography of the African American Image, 1978-1994.

ERIC Educational Resources Information Center

Klotman, Phyllis R.; Gibson, Gloria J.

A reference guide on African American film professionals, this book is a companion volume to the earlier "Frame by Frame I." It focuses on giving credit to African Americans who have contributed their talents to a film industry that has scarcely recognized their contributions, building on the aforementioned "Frame by Frame I,"…

Radio stars - A possible link between the Hipparcos optical reference frame and an extra-galactic very long baseline interferometry reference frame

NASA Technical Reports Server (NTRS)

Lestrade, J.-F.; Preston, R. A.; Slade, M. A.

1983-01-01

The concept of typing the Hipparcos optical and the JPL VLBI frames of reference by means of VLBI measurements of the positions and proper motions of the radio components of some bright stars is considered. The properties of the thermal and non-thermal radio-stars are discussed and 22 candidate stars are selected to achieve this tie. A description is given of the first VLBI attempt to detect these stars on the intercontinental baselines of the Deep Space Network with the Mark II recording system.

Analog Landau-He-McKellar-Wilkens quantization due to noninertial effects of the Fermi-Walker reference frame

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakke, Knut

2010-05-15

We will show that when a neutral particle with permanent electric dipole moment interacts with a specific field configuration when the local reference frames of the observers are Fermi-Walker transported, the Landau quantization analog to the He-McKellar-Wilkens setup arises in the nonrelativistic quantum dynamics of the neutral particle due the noninertial effects of the Fermi-Walker reference frame. We show that the noninertial effects do not break the infinity degeneracy of the energy levels, but in this case, the cyclotron frequency depends on the angular velocity.

A Celestial Reference Frame at X/ka-Band (8.4/32 Ghz) for Deep Space Navigation

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Garcia-Miro, C.; Horiuchi, S.; Romero-Wolf, A.; Snedeker, L.; Sotuela, I.

2012-01-01

Deep space tracking and navigation are done in a quasi-inertial reference frame based upon the angular positions of distant active galactic nuclei (AGN). These objects, which are found at extreme distances characterized by median redshifts of z = 1, are ideal for reference frame definition because they exhibit no measurable parallax or proper motion. They are thought to be powered by super massive black holes whose gravitational energy drives galactic sized relativistic jets. These jets produce synchrotron emissions which are detectable by modern radio techniques such as Very Long baseline Interferometry (VLBI).

Quantum mechanics in noninertial reference frames: Violations of the nonrelativistic equivalence principle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klink, W.H.; Wickramasekara, S., E-mail: wickrama@grinnell.edu; Department of Physics, Grinnell College, Grinnell, IA 50112

2014-01-15

In previous work we have developed a formulation of quantum mechanics in non-inertial reference frames. This formulation is grounded in a class of unitary cocycle representations of what we have called the Galilean line group, the generalization of the Galilei group that includes transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as is the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. A special feature of these previously constructed representations is that they all respect the non-relativistic equivalence principle, wherein the fictitious forces associated with linear acceleration canmore » equivalently be described by gravitational forces. In this paper we exhibit a large class of cocycle representations of the Galilean line group that violate the equivalence principle. Nevertheless the classical mechanics analogue of these cocycle representations all respect the equivalence principle. -- Highlights: •A formulation of Galilean quantum mechanics in non-inertial reference frames is given. •The key concept is the Galilean line group, an infinite dimensional group. •A large class of general cocycle representations of the Galilean line group is constructed. •These representations show violations of the equivalence principle at the quantum level. •At the classical limit, no violations of the equivalence principle are detected.« less

Language supports young children’s use of spatial relations to remember locations

PubMed Central

Miller, Hilary E.; Patterson, Rebecca; Simmering, Vanessa R.

2016-01-01

Two experiments investigated the role of language in children’s spatial recall performance. In particular, we assessed whether selecting an intrinsic reference frame could be improved through verbal encoding. Selecting an intrinsic reference frame requires remembering locations relative to nearby objects independent of one’s body (egocentric) or distal environmental (allocentric) cues, and does not reliably occur in children under 5 years of age (Nardini, Burgess, Breckenridge, & Atkinson, 2006). The current studies tested the relation between spatial language and 4-year-olds’ selection of an intrinsic reference frame in spatial recall. Experiment 1 showed that providing 4-year-olds with location-descriptive cues during (Exp. 1a) or before (Exp. 1b) the recall task improved performance both overall and specifically on trials relying most on an intrinsic reference frame. Additionally, children’s recall performance was predicted by their verbal descriptions of the task space (Exp. 1a control condition). Non-verbally highlighting relations among objects during the recall task (Exp. 2) supported children’s performance relative to the control condition, but significantly less than the location-descriptive cues. These results suggest that the ability to verbally represent relations is a potential mechanism that could account for developmental changes in the selection of an intrinsic reference frame during spatial recall. PMID:26896902

Language supports young children's use of spatial relations to remember locations.

PubMed

Miller, Hilary E; Patterson, Rebecca; Simmering, Vanessa R

2016-05-01

Two experiments investigated the role of language in children's spatial recall performance. In particular, we assessed whether selecting an intrinsic reference frame could be improved through verbal encoding. Selecting an intrinsic reference frame requires remembering locations relative to nearby objects independent of one's body (egocentric) or distal environmental (allocentric) cues, and does not reliably occur in children under 5 years of age (Nardini, Burgess, Breckenridge, & Atkinson, 2006). The current studies tested the relation between spatial language and 4-year-olds' selection of an intrinsic reference frame in spatial recall. Experiment 1 showed that providing 4-year-olds with location-descriptive cues during (Exp. 1a) or before (Exp. 1b) the recall task improved performance both overall and specifically on trials relying most on an intrinsic reference frame. Additionally, children's recall performance was predicted by their verbal descriptions of the task space (Exp. 1a control condition). Non-verbally highlighting relations among objects during the recall task (Exp. 2) supported children's performance relative to the control condition, but significantly less than the location-descriptive cues. These results suggest that the ability to verbally represent relations is a potential mechanism that could account for developmental changes in the selection of an intrinsic reference frame during spatial recall. Copyright © 2016 Elsevier B.V. All rights reserved.

In vitro validation and reliability study of electromagnetic skin sensors for evaluation of end range of motion positions of the hip.

PubMed

Audenaert, E A; Vigneron, L; Van Hoof, T; D'Herde, K; van Maele, G; Oosterlinck, D; Pattyn, C

2011-12-01

There is growing evidence that femoroacetabular impingement (FAI) is a probable risk factor for the development of early osteoarthritis in the nondysplastic hip. As FAI arises with end range of motion activities, measurement errors related to skin movement might be higher than anticipated when using previously reported methods for kinematic evaluation of the hip. We performed an in vitro validation and reliability study of a noninvasive method to define pelvic and femur positions in end range of motion activities of the hip using an electromagnetic tracking device. Motion data, collected from sensors attached to the bone and skin of 11 cadaver hips, were simultaneously obtained and compared in a global reference frame. Motion data were then transposed in the hip joint local coordinate systems. Observer-related variability in locating the anatomical landmarks required to define the local coordinate system and variability of determining the hip joint center was evaluated. Angular root mean square (RMS) differences between the bony and skin sensors averaged 3.2° (SD 3.5°) and 1.8° (SD 2.3°) in the global reference frame for the femur and pelvic sensors, respectively. Angular RMS differences between the bony and skin sensors in the hip joint local coordinate systems ranged at end range of motion and dependent on the motion under investigation from 1.91 to 5.81°. The presented protocol for evaluation of hip motion seems to be suited for the 3-D description of motion relevant to the experimental and clinical evaluation of femoroacetabular impingement.

Framing deadly domestic violence: why the media's spin matters in newspaper coverage of femicide.

PubMed

Gillespie, Lane Kirkland; Richards, Tara N; Givens, Eugena M; Smith, M Dwayne

2013-02-01

The news media play a substantial role in shaping society's perceptions of social issues, including domestic violence. However, minimal research has been conducted to examine whether news media frame stories of femicide within the context of domestic violence. Using frame analysis, the present research compares newspaper articles representing 113 cases of femicide that define the murder as domestic violence to a random sample of 113 cases without coverage defining the femicide as domestic violence. Findings indicate that both groups are represented by multiple frames, including a previously unidentified frame that places the femicide in the context of domestic violence as a social problem.

Current Trends in Satellite Laser Ranging

NASA Technical Reports Server (NTRS)

Pearlman, M. R.; Appleby, G. M.; Kirchner, G.; McGarry, J.; Murphy, T.; Noll, C. E.; Pavlis, E. C.; Pierron, F.

2010-01-01

Satellite Laser Ranging (SLR) techniques are used to accurately measure the distance from ground stations to retroreflectors on satellites and the moon. SLR is one of the fundamental techniques that define the international Terrestrial Reference Frame (iTRF), which is the basis upon which we measure many aspects of global change over space, time, and evolving technology. It is one of the fundamental techniques that define at a level of precision of a few mm the origin and scale of the ITRF. Laser Ranging provides precision orbit determination and instrument calibration/validation for satellite-borne altimeters for the better understanding of sea level change, ocean dynamics, ice budget, and terrestrial topography. Laser ranging is also a tool to study the dynamics of the Moon and fundamental constants. Many of the GNSS satellites now carry retro-reflectors for improved orbit determination, harmonization of reference frames, and in-orbit co-location and system performance validation. The GNSS Constellations will be the means of making the reference frame available to worldwide users. Data and products from these measurements support key aspects of the GEOSS 10-Year implementation Plan adopted on February 16, 2005, The ITRF has been identified as a key contribution of the JAG to GEOSS and the ILRS makes a major contribution for its development since its foundation. The ILRS delivers weekly additional realizations that are accumulated sequentially to extend the ITRF and the Earth Orientation Parameter (EOP) series with a daily resolution. Additional products are currently under development such as precise orbits of satellites, EOP with daily availability, low-degree gravitational harmonics for studies of Earth dynamics and kinematics, etc. SLR technology continues to evolve toward the next generation laser ranging systems as programmatic requirements become more stringent. Ranging accuracy is improving as higher repetition rate, narrower pulse lasers and faster detectors are implemented. Automation and pass interleaving at some stations is already expanding temporal coverage. Web-based safety keys are allowing the SLR network stations to range to optically vulnerable satellites. Some stations are experimenting with two-wavelength operation as a means of better understanding the atmospheric refraction and with very low power laser to improve eye-safety conditions. New retroreflector designs are improving the signal link and enable daylight ranging. Dramatic improvements have also been made with lunar ranging with the new APOLLO Site in New ?Mexico, USA and the upgraded lunar station "MEO" in Grasse,

Second-order Compton-Getting effect on arbitrary intensity distribution

NASA Technical Reports Server (NTRS)

Ng, C. K.

1985-01-01

Theoretical studies of energetic particles in space are often referred to a special frame of reference. To compare theory with experiment, one has to transform the particle distribution from the special frame to the observer's frame, or vice versa. Various methods have been derived to obtain the directional distribution in the comoving frame from the directional fluxes measured on a spacecraft. These methods have become progressively complicated as increasingly detailed directional particle data become available. A set of 2nd order correct formulae for the transformation of an arbitrary differential intensity distribution, expressed as a series of spherical harmonics, between any two frames in constant relative motion is presented. These formulae greatly simplify the complicated procedures currently in use for the determination of the differential intensity distribution in a comoving frame.

SU-F-P-28: A Method of Maximize the Noncoplanar Beam Orientations and Assure the Beam Delivery Clearance for Stereotactic Body Radiation Therapy (SBRT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, J

2016-06-15

Purpose: Develop a method to maximize the noncoplanar beam orientations and assure the beam delivery clearance for SBRT, therefore, optimize the dose conformality to the target, increase the dose sparing to the critical normal organs and reduce the hot spots in the body. Methods: A SBRT body frame (Elekta, Stockholm, Sweden) was used for patient immobilization and target localization. The SBRT body frame has CT fiducials on its side frames. After patient’s CT scan, the radiation treatment isocenter was defined and its coordinators referring to the body frame was calculated in the radiation treatment planning process. Meanwhile, initial beam orientationsmore » were designed based on the patient target and critical organ anatomy. The body frame was put on the linear accelerator couch and positioned to the calculated isocenter. Initially designed beam orientations were manually measured by tuning the body frame position on the couch, the gantry and couch angles. The finalized beam orientations were put into the treatment planning for dosimetric calculations. Results: Without patient presence, an optimal set of beam orientations were designed and validated. The radiation treatment plan was optimized and guaranteed for delivery clearance. Conclusion: The developed method is beneficial and effective in SBRT treatment planning for individual patient. It first allows maximizing the achievable noncoplanar beam orientation space, therefore, optimize the treatment plan for specific patient. It eliminates the risk that a plan needs to be modified due to the gantry and couch collision during patient setup.« less

Digital movie-based on automatic titrations.

PubMed

Lima, Ricardo Alexandre C; Almeida, Luciano F; Lyra, Wellington S; Siqueira, Lucas A; Gaião, Edvaldo N; Paiva Junior, Sérgio S L; Lima, Rafaela L F C

2016-01-15

This study proposes the use of digital movies (DMs) in a flow-batch analyzer (FBA) to perform automatic, fast and accurate titrations. The term used for this process is "Digital movie-based on automatic titrations" (DMB-AT). A webcam records the DM during the addition of the titrant to the mixing chamber (MC). While the DM is recorded, it is decompiled into frames ordered sequentially at a constant rate of 26 frames per second (FPS). The first frame is used as a reference to define the region of interest (ROI) of 28×13pixels and the R, G and B values, which are used to calculate the Hue (H) values for each frame. The Pearson's correlation coefficient (r) is calculated between the H values of the initial frame and each subsequent frame. The titration curves are plotted in real time using the r values and the opening time of the titrant valve. The end point is estimated by the second derivative method. A software written in C language manages all analytical steps and data treatment in real time. The feasibility of the method was attested by application in acid/base test samples and edible oils. Results were compared with classical titration and did not present statistically significant differences when the paired t-test at the 95% confidence level was applied. The proposed method is able to process about 117-128 samples per hour for the test and edible oil samples, respectively, and its precision was confirmed by overall relative standard deviation (RSD) values, always less than 1.0%. Copyright © 2015 Elsevier B.V. All rights reserved.

OOM - OBJECT ORIENTATION MANIPULATOR, VERSION 6.1

NASA Technical Reports Server (NTRS)

Goza, S. P.

1994-01-01

The Object Orientation Manipulator (OOM) is an application program for creating, rendering, and recording three-dimensional computer-generated still and animated images. This is done using geometrically defined 3D models, cameras, and light sources, referred to collectively as animation elements. OOM does not provide the tools necessary to construct 3D models; instead, it imports binary format model files generated by the Solid Surface Modeler (SSM). Model files stored in other formats must be converted to the SSM binary format before they can be used in OOM. SSM is available as MSC-21914 or as part of the SSM/OOM bundle, COS-10047. Among OOM's features are collision detection (with visual and audio feedback), the capability to define and manipulate hierarchical relationships between animation elements, stereographic display, and ray-traced rendering. OOM uses Euler angle transformations for calculating the results of translation and rotation operations. OOM provides an interactive environment for the manipulation and animation of models, cameras, and light sources. Models are the basic entity upon which OOM operates and are therefore considered the primary animation elements. Cameras and light sources are considered secondary animation elements. A camera, in OOM, is simply a location within the three-space environment from which the contents of the environment are observed. OOM supports the creation and full animation of cameras. Light sources can be defined, positioned and linked to models, but they cannot be animated independently. OOM can simultaneously accommodate as many animation elements as the host computer's memory permits. Once the required animation elements are present, the user may position them, orient them, and define any initial relationships between them. Once the initial relationships are defined, the user can display individual still views for rendering and output, or define motion for the animation elements by using the Interp Animation Editor. The program provides the capability to save still images, animated sequences of frames, and the information that describes the initialization process for an OOM session. OOM provides the same rendering and output options for both still and animated images. OOM is equipped with a robust model manipulation environment featuring a full screen viewing window, a menu-oriented user interface, and an interpolative Animation Editor. It provides three display modes: solid, wire frame, and simple, that allow the user to trade off visual authenticity for update speed. In the solid mode, each model is drawn based on the shading characteristics assigned to it when it was built. All of the shading characteristics supported by SSM are recognized and properly rendered in this mode. If increasing model complexity impedes the operation of OOM in this mode, then wireframe and simple modes are available. These provide substantially faster screen updates than solid mode. The creation and placement of cameras and light sources is under complete control of the user. One light source is provided in the default element set. It is modeled as a direct light source providing a type of lighting analogous to that provided by the Sun. OOM can accommodate as many light sources as the memory of the host computer permits. Animation is created in OOM using a technique called key frame interpolation. First, various program functions are used to load models, load or create light sources and cameras, and specify initial positions for each element. When these steps are completed, the Interp function is used to create an animation sequence for each element to be animated. An animation sequence consists of a user-defined number of frames (screen images) with some subset of those being defined as key frames. The motion of the element between key frames is interpolated automatically by the software. Key frames thus act as transition points in the motion of an element. This saves the user from having to individually define element data at each frame of a sequence. Animation frames and still images can be output to videotape recorders, film recorders, color printers, and disk files. OOM is written in C-language for implementation on SGI IRIS 4D series workstations running the IRIX operating system. A minimum of 8Mb of RAM is recommended for this program. The standard distribution medium for OOM is a .25 inch streaming magnetic IRIX tape cartridge in UNIX tar format. OOM is also offered as a bundle with a related program, SSM (Solid Surface Modeler). Please see the abstract for SSM/OOM (COS-10047) for information about the bundled package. OOM was released in 1993.

Importance of baseline specification in evaluating conservation interventions and achieving no net loss of biodiversity.

PubMed

Bull, J W; Gordon, A; Law, E A; Suttle, K B; Milner-Gulland, E J

2014-06-01

There is an urgent need to improve the evaluation of conservation interventions. This requires specifying an objective and a frame of reference from which to measure performance. Reference frames can be baselines (i.e., known biodiversity at a fixed point in history) or counterfactuals (i.e., a scenario that would have occurred without the intervention). Biodiversity offsets are interventions with the objective of no net loss of biodiversity (NNL). We used biodiversity offsets to analyze the effects of the choice of reference frame on whether interventions met stated objectives. We developed 2 models to investigate the implications of setting different frames of reference in regions subject to various biodiversity trends and anthropogenic impacts. First, a general analytic model evaluated offsets against a range of baseline and counterfactual specifications. Second, a simulation model then replicated these results with a complex real world case study: native grassland offsets in Melbourne, Australia. Both models showed that achieving NNL depended upon the interaction between reference frame and background biodiversity trends. With a baseline, offsets were less likely to achieve NNL where biodiversity was decreasing than where biodiversity was stable or increasing. With a no-development counterfactual, however, NNL was achievable only where biodiversity was declining. Otherwise, preventing development was better for biodiversity. Uncertainty about compliance was a stronger determinant of success than uncertainty in underlying biodiversity trends. When only development and offset locations were considered, offsets sometimes resulted in NNL, but not across an entire region. Choice of reference frame determined feasibility and effort required to attain objectives when designing and evaluating biodiversity offset schemes. We argue the choice is thus of fundamental importance for conservation policy. Our results shed light on situations in which biodiversity offsets may be an inappropriate policy instrument.

Quantum mechanics in non-inertial reference frames: Time-dependent rotations and loop prolongations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klink, W.H., E-mail: william-klink@uiowa.edu; Wickramasekara, S., E-mail: wickrama@grinnell.edu; Department of Physics, Grinnell College, Grinnell, IA 50112

2013-09-15

This is the fourth in a series of papers on developing a formulation of quantum mechanics in non-inertial reference frames. This formulation is grounded in a class of unitary cocycle representations of what we have called the Galilean line group, the generalization of the Galilei group to include transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. In previous work, we have shown that there exist representations of the Galilean line group that uphold the non-relativistic equivalence principle asmore » well as representations that violate the equivalence principle. In these previous studies, the focus was on linear accelerations. In this paper, we undertake an extension of the formulation to include rotational accelerations. We show that the incorporation of rotational accelerations requires a class of loop prolongations of the Galilean line group and their unitary cocycle representations. We recover the centrifugal and Coriolis force effects from these loop representations. Loops are more general than groups in that their multiplication law need not be associative. Hence, our broad theoretical claim is that a Galilean quantum theory that holds in arbitrary non-inertial reference frames requires going beyond groups and group representations, the well-established framework for implementing symmetry transformations in quantum mechanics. -- Highlights: •A formulation of Galilean quantum mechanics in non-inertial reference frames is presented. •The Galilei group is generalized to infinite dimensional Galilean line group. •Loop prolongations of Galilean line group contain central extensions of Galilei group. •Unitary representations of the loops are constructed. •These representations lead to terms in the Hamiltonian corresponding to fictitious forces, including centrifugal and Coriolis forces.« less

Motion-based nearest vector metric for reference frame selection in the perception of motion.

PubMed

Agaoglu, Mehmet N; Clarke, Aaron M; Herzog, Michael H; Ögmen, Haluk

2016-05-01

We investigated how the visual system selects a reference frame for the perception of motion. Two concentric arcs underwent circular motion around the center of the display, where observers fixated. The outer (target) arc's angular velocity profile was modulated by a sine wave midflight whereas the inner (reference) arc moved at a constant angular speed. The task was to report whether the target reversed its direction of motion at any point during its motion. We investigated the effects of spatial and figural factors by systematically varying the radial and angular distances between the arcs, and their relative sizes. We found that the effectiveness of the reference frame decreases with increasing radial- and angular-distance measures. Drastic changes in the relative sizes of the arcs did not influence motion reversal thresholds, suggesting no influence of stimulus form on perceived motion. We also investigated the effect of common velocity by introducing velocity fluctuations to the reference arc as well. We found no effect of whether or not a reference frame has a constant motion. We examined several form- and motion-based metrics, which could potentially unify our findings. We found that a motion-based nearest vector metric can fully account for all the data reported here. These findings suggest that the selection of reference frames for motion processing does not result from a winner-take-all process, but instead, can be explained by a field whose strength decreases with the distance between the nearest motion vectors regardless of the form of the moving objects.

Cross-Sensory Transfer of Reference Frames in Spatial Memory

ERIC Educational Resources Information Center

Kelly, Jonathan W.; Avraamides, Marios N.

2011-01-01

Two experiments investigated whether visual cues influence spatial reference frame selection for locations learned through touch. Participants experienced visual cues emphasizing specific environmental axes and later learned objects through touch. Visual cues were manipulated and haptic learning conditions were held constant. Imagined perspective…

Dynamical Reference Frame: Current Relevance and Future Prospects

NASA Technical Reports Server (NTRS)

Standish, E. M., Jr

2000-01-01

Planetary and lunar ephemerides are no longer used for the determination of inertial space. Instead, the new fundamental reference frame, the International Celestial Reference Frame (ICRF), is inherently less susceptible to extraneous, non-inertial rotations than a dynamical reference frame determined by the ephemerides would be. Consequently, the ephemerides are now adjusted onto the ICRF, and they are fit to two modern, accurate observational data types: ranging (radar, lunar laser, spacecraft) and Very Long Baseline Interferometry (VLBI) (of spacecraft near planets). The uncertainties remaining in the inner planet ephemerides are on the order of 1 kilometer, both in relative positions between the bodies and in the orientation of the inner system as a whole. The predictive capabilities of the inner planet ephemerides are limited by the uncertainties in the masses of many asteroids. For this reason, future improvements to the ephemerides must await determinations of many asteroid masses. Until then, it will be necessary to constantly update the ephemerides with a continuous supply of observational data.

Effects of adopting new precession, nutation and equinox corrections on the terrestrial reference frame

NASA Technical Reports Server (NTRS)

Zhu, S. Y.; Mueller, I. I.

1982-01-01

The effect of adopting definitive precession and equinox corrections on the terrestrial reference frame was investigated. It is noted that the effect on polar motion is a diurnal periodic term with an amplitude increasing linearly in time whole on UT1 it is a linear term: general principles are given to determine the effects of small rotations of the frame of a conventional inertial reference system (CIS) on the frame of the conventional terrestrial reference system (CTS); seven CTS options are presented, one of which is necessary to accommodate such rotation. Accommodating possible future changes in the astronomical nutation is discussed. The effects of differences which may exist between the various CTS's and CIS's on Earth rotation parameters (ERP) and how these differences can be determined are examined. It is shown that the CTS differences can be determined from observations made at the same site. The CIS differences by comparing the ERP's are determined by the different techniques during the same time period.

Effects of adopting new precession, nutation and equinox corrections on the terrestrial reference frame

NASA Technical Reports Server (NTRS)

Zhu, S. Y.; Mueller, I. I.

1982-01-01

The effects of adopting new definitive precession and equinox corrections on the terrestrial reference frame was investigated. It is noted that: (1) the effect on polar motion is a diurnal periodic term with an amplitude increasing linearly in time whole on UT1 it is a linear term; (2) general principles are given to determine the effects of small rotations of the frame of a conventional inertial reference system (CIS) on the frame of the conventional terrestrial reference system (CTS); (3) seven CTS options are presented, one of which is necessary to accommodate such rotation. Accommodating possible future changes in the astronomical nutation is discussed. The effects of differences which may exist between the various CTS's and CIS's on Earth rotation parameters (ERP) and how these differences can be determined are examined. It is shown that the CTS differences can be determined from observations made at the same site, while the CIS differences by comparing the ERP's determined by the different techniques during the same time period.

Time evolution of an SLR reference frame

NASA Astrophysics Data System (ADS)

Angermann, D.; Gerstl, M.; Kelm, R.; Müller, H.; Seemüller, W.; Vei, M.

2002-07-01

On the basis of LAGEOS-1 and LAGEOS-2 data we computed a 10-years (1990-2000) solution for SLR station positions and velocities. The paper describes the data processing with the DGFI software package DOGS. We present results for station coordinates and their time variation for 41 stations of the global SLR network, and discuss the stability and time evolution of the SLR reference frame established in the same way. We applied different methods to assess the quality and consistency of the SLR results. The results presented in this paper include: (1) a time series of weekly estimated station coordinates; (2) a comparison of a 10-year LAGEOS-1 and LAGEOS-2 solution; (3) a comparison of 2.5-year solutions with the combined 10-year solution to assess the internal stability and the time evolution of the SLR reference frame; (4) a comparison of the SLR reference frame with ITRF97; and (5) a comparison of SLR station velocities with those of ITRF97 and NNR NUVEL-1A.

Estimating the Geocenter from GNSS Observations

NASA Astrophysics Data System (ADS)

Dach, Rolf; Michael, Meindl; Beutler, Gerhard; Schaer, Stefan; Lutz, Simon; Jäggi, Adrian

2014-05-01

The satellites of the Global Navigation Satellite Systems (GNSS) are orbiting the Earth according to the laws of celestial mechanics. As a consequence, the satellites are sensitive to the coordinates of the center of mass of the Earth. The coordinates of the (ground) tracking stations are referring to the center of figure as the conventional origin of the reference frame. The difference between the center of mass and center of figure is the instantaneous geocenter. Following this definition the global GNSS solutions are sensitive to the geocenter. Several studies demonstrated strong correlations of the GNSS-derived geocenter coordinates with parameters intended to absorb radiation pressure effects acting on the GNSS satellites, and with GNSS satellite clock parameters. One should thus pose the question to what extent these satellite-related parameters absorb (or hide) the geocenter information. A clean simulation study has been performed to answer this question. The simulation environment allows it in particular to introduce user-defined shifts of the geocenter (systematic inconsistencies between the satellite's and station's reference frames). These geocenter shifts may be recovered by the mentioned parameters - provided they were set up in the analysis. If the geocenter coordinates are not estimated, one may find out which other parameters absorb the user-defined shifts of the geocenter and to what extent. Furthermore, the simulation environment also allows it to extract the correlation matrix from the a posteriori covariance matrix to study the correlations between different parameter types of the GNSS analysis system. Our results show high degrees of correlations between geocenter coordinates, orbit-related parameters, and satellite clock parameters. These correlations are of the same order of magnitude as the correlations between station heights, troposphere, and receiver clock parameters in each regional or global GNSS network analysis. If such correlations are accepted in a GNSS analysis when estimating station coordinates, geocenter coordinates must be considered as mathematically estimable in a global GNSS analysis. The geophysical interpretation may of course become difficult, e.g., if insufficient orbit models are used.

Coordination of multiple robot arms

NASA Technical Reports Server (NTRS)

Barker, L. K.; Soloway, D.

1987-01-01

Kinematic resolved-rate control from one robot arm is extended to the coordinated control of multiple robot arms in the movement of an object. The structure supports the general movement of one axis system (moving reference frame) with respect to another axis system (control reference frame) by one or more robot arms. The grippers of the robot arms do not have to be parallel or at any pre-disposed positions on the object. For multiarm control, the operator chooses the same moving and control reference frames for each of the robot arms. Consequently, each arm then moves as though it were carrying out the commanded motions by itself.

VLBI astrometry and the Hipparcos link to the extragalactic reference frame

NASA Technical Reports Server (NTRS)

Lestrade, J.-F.; Preston, R. A.; Gabuzda, D. C.; Phillips, R. B.

1991-01-01

Intermediate results are reported from a program of VLBI radio observations designed to establish a link between the rotating reference frame of the ESA Hipparcos astrometric satellite and the extragalactic VLBI frame being developed by the International Earth Rotation Service. A group of 12 link stars have been observed at various epochs since 1982, and more observations are being undertaken during the 3-yr Hipparcos mission (1989-1992). Analysis of data on Algol indicates that phase-reference VLBI can determine an expected sky displacement of 4 marcsec with an uncertainty of 0.5 marcsec, even when the activity is only a few mJy.

The right frame of reference makes it simple: an example of introductory mechanics supported by video analysis of motion

NASA Astrophysics Data System (ADS)

Klein, P.; Gröber, S.; Kuhn, J.; Fleischhauer, A.; Müller, A.

2015-01-01

The selection and application of coordinate systems is an important issue in physics. However, considering different frames of references in a given problem sometimes seems un-intuitive and is difficult for students. We present a concrete problem of projectile motion which vividly demonstrates the value of considering different frames of references. We use this example to explore the effectiveness of video-based motion analysis (VBMA) as an instructional technique at university level in enhancing students’ understanding of the abstract concept of coordinate systems. A pilot study with 47 undergraduate students indicates that VBMA instruction improves conceptual understanding of this issue.

Array Of Sensors Measures Broadband Radiation

NASA Technical Reports Server (NTRS)

Hoffman, James W.; Grush, Ronald G.

1994-01-01

Multiple broadband radiation sensors aimed at various portions of total field of view. All sensors mounted in supporting frame, serving as common heat sink and temperature reference. Each sensor includes heater winding and differential-temperature-sensing bridge circuit. Power in heater winding adjusted repeatedly in effort to balance bridge circuit. Intended to be used aboard satellite in orbit around Earth to measure total radiation emitted, at various viewing angles, by mosaic of "footprint" areas (each defined by its viewing angle) on surface of Earth. Modified versions of array useful for angle-resolved measurements of broadband radiation in laboratory and field settings on Earth.

The Second International Celestial Reference Frame (ICRF2)

NASA Technical Reports Server (NTRS)

Ma, Chopo

2010-01-01

The ICRF2 catalog was constructed by the IERS/IVS Working Group with oversight by the IAU Working Group. Derived using data from August 1979 through March 2009, it is a great improvement over the original ICRF with 3414 extragalactic radio source positions, a noise floor of 40 microarcsec, and axis stability of 10 microarcsec. Significant refinements were made in the selection of defining sources, modeling, and the integration of CRF, TRF, and EOP. The adoption of the ICRF2 was approved by the IAU in Resolution B3 at the XXVII IAU General Assembly and became effective 1 January 2010.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doug Blankenship

Natural fracture data from wells 33-7, 33A-7,52A-7, 52B-7 and 83-11 at West Flank. Fracture orientations were determined from image logs of these wells (see accompanying submissions). Data files contain depth, apparent (in wellbore reference frame) and true (in geographic reference frame) azimuth and dip, respectively.

On Translators' Cultural Frame of Functionist Reference

ERIC Educational Resources Information Center

Fu, Zhiyi

2009-01-01

A deep cognition with translators' cultural frame of functionist reference can help instructors and teachers adjust and extend patterns and schemes of translation and generate the optimal classroom conditions for acquisition of the target language. The author of the paper, in the perspectives of motivational, cognitive and communicative…

Reference Frames and 3-D Shape Perception of Pictured Objects: On Verticality and Viewpoint-From-Above

PubMed Central

van Doorn, Andrea J.; Wagemans, Johan

2016-01-01

Research on the influence of reference frames has generally focused on visual phenomena such as the oblique effect, the subjective visual vertical, the perceptual upright, and ambiguous figures. Another line of research concerns mental rotation studies in which participants had to discriminate between familiar or previously seen 2-D figures or pictures of 3-D objects and their rotated versions. In the present study, we disentangled the influence of the environmental and the viewer-centered reference frame, as classically done, by comparing the performances obtained in various picture and participant orientations. However, this time, the performance is the pictorial relief: the probed 3-D shape percept of the depicted object reconstructed from the local attitude settings of the participant. Comparisons between the pictorial reliefs based on different picture and participant orientations led to two major findings. First, in general, the pictorial reliefs were highly similar if the orientation of the depicted object was vertical with regard to the environmental or the viewer-centered reference frame. Second, a viewpoint-from-above interpretation could almost completely account for the shears occurring between the pictorial reliefs. More specifically, the shears could largely be considered as combinations of slants generated from the viewpoint-from-above, which was determined by the environmental as well as by the viewer-centered reference frame. PMID:27433329

Ipsilateral wrist-ankle movements in the sagittal plane encoded in extrinsic reference frame.

PubMed

Muraoka, Tetsuro; Ishida, Yuki; Obu, Takashi; Crawshaw, Larry; Kanosue, Kazuyuki

2013-04-01

When performing oscillatory movements of two joints in the sagittal plane, there is a directional constraint for performing such movements. Previous studies could not distinguish whether the directional constraint reflected movement direction encoded in the extrinsic (outside the body) reference frame or in the intrinsic (the participants' torso/head) reference frame since participants performed coordinated movements in a sitting position where the torso/head was stationary relative to the external world. In order to discern the reference frame in the present study, participants performed paced oscillatory movements of the ipsilateral wrist and ankle in the sagittal plane in a standing position so that the torso/head moved relative to the external world. The coordinated movements were performed in one of two modes of coordination, moving the hand upward concomitant with either ankle plantarflexion or ankle dorsiflexion. The same directional mode relative to extrinsic space was more stable and accurate as compared with the opposite directional mode. When forearm position was changed from the pronated position to the supinated position, similar results were obtained, indicating that the results were independent of a particular coupling of muscles. These findings suggest that the directional constraint on ipsilateral joints movements in the sagittal plane reflects movement direction encoded in the extrinsic reference frame. Copyright © 2013 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Flying over uneven moving terrain based on optic-flow cues without any need for reference frames or accelerometers.

PubMed

Expert, Fabien; Ruffier, Franck

2015-02-26

Two bio-inspired guidance principles involving no reference frame are presented here and were implemented in a rotorcraft, which was equipped with panoramic optic flow (OF) sensors but (as in flying insects) no accelerometer. To test these two guidance principles, we built a tethered tandem rotorcraft called BeeRotor (80 grams), which was tested flying along a high-roofed tunnel. The aerial robot adjusts its pitch and hence its speed, hugs the ground and lands safely without any need for an inertial reference frame. The rotorcraft's altitude and forward speed are adjusted via two OF regulators piloting the lift and the pitch angle on the basis of the common-mode and differential rotor speeds, respectively. The robot equipped with two wide-field OF sensors was tested in order to assess the performances of the following two systems of guidance involving no inertial reference frame: (i) a system with a fixed eye orientation based on the curved artificial compound eye (CurvACE) sensor, and (ii) an active system of reorientation based on a quasi-panoramic eye which constantly realigns its gaze, keeping it parallel to the nearest surface followed. Safe automatic terrain following and landing were obtained with CurvACE under dim light to daylight conditions and the active eye-reorientation system over rugged, changing terrain, without any need for an inertial reference frame.

FRAME, animal experimentation and the Three Rs: past, present and future.

PubMed

Balls, Michael

2009-12-01

At the opening of a meeting to celebrate the 50th anniversary of the publication of The Principles of Humane Experimental Technique, by W.M.S. Russell and R.L. Burch, and the 40th anniversary of the establishment of FRAME, some comments on the early days of the Charity are made, with particular reference to the special contributions made by its founder-Chairman, Dorothy Hegarty, and the author's own appointment as a Trustee, and later as Chairman. Reference is made to some key events and successes, and especially to the importance of FRAME's move from London to Nottingham, and the establishment of an ongoing collaboration with the University of Nottingham, including the setting-up of the FRAME Alternatives Laboratory. 2009 FRAME.

Modeling the impact of climate change in Germany with biosphere models for long-term safety assessment of nuclear waste repositories.

PubMed

Staudt, C; Semiochkina, N; Kaiser, J C; Pröhl, G

2013-01-01

Biosphere models are used to evaluate the exposure of populations to radionuclides from a deep geological repository. Since the time frame for assessments of long-time disposal safety is 1 million years, potential future climate changes need to be accounted for. Potential future climate conditions were defined for northern Germany according to model results from the BIOCLIM project. Nine present day reference climate regions were defined to cover those future climate conditions. A biosphere model was developed according to the BIOMASS methodology of the IAEA and model parameters were adjusted to the conditions at the reference climate regions. The model includes exposure pathways common to those reference climate regions in a stylized biosphere and relevant to the exposure of a hypothetical self-sustaining population at the site of potential radionuclide contamination from a deep geological repository. The end points of the model are Biosphere Dose Conversion factors (BDCF) for a range of radionuclides and scenarios normalized for a constant radionuclide concentration in near-surface groundwater. Model results suggest an increased exposure of in dry climate regions with a high impact of drinking water consumption rates and the amount of irrigation water used for agriculture. Copyright © 2012 Elsevier Ltd. All rights reserved.

Limited Aspects of Reality: Frames of Reference in Language Assessment

ERIC Educational Resources Information Center

Fulcher, Glenn; Svalberg, Agneta

2013-01-01

Language testers operate within two frames of reference: norm-referenced (NRT) and criterion-referenced testing (CRT). The former underpins the world of large-scale standardized testing that prioritizes variability and comparison. The latter supports substantive score meaning in formative and domain specific assessment. Some claim that the…

Frames of Reference in African Proverbs on Disability.

ERIC Educational Resources Information Center

Devlieger, Patrick J.

1999-01-01

Fifty-five proverbs relating to disability were collected from sub-Saharan African countries and analyzed for larger frames of reference of personhood and cosmogony. Themes include warnings against laughing at a disabled person, personhood, existential insecurity, acceptance of what is, and the function and nature of disability. (DB)

Equity and Satisfaction among the Elderly.

ERIC Educational Resources Information Center

Carp, Frances M.; And Others

1982-01-01

Compared the contribution of equity to that of aspiration, friends, and typical American as frames-of-reference for current status in predicting domain satisfactions and overall well-being. Results confirmed the relevance of an equity frame-of-reference in accounting for the satisfaction of older people with specific conditions of their lives.…

Understanding Frame-of-Reference Training Success: A Social Learning Theory Perspective

ERIC Educational Resources Information Center

Sulsky, Lorne M.; Kline, Theresa J. B.

2007-01-01

Employing the social learning theory (SLT) perspective on training, we analysed the effects of alternative frame-of-reference (FOR) training protocols on various criteria of training effectiveness. Undergraduate participants (N = 65) were randomly assigned to one of four FOR training conditions and a control condition. Training effectiveness was…

Electrochemical cell

DOEpatents

Nagy, Z.; Yonco, R.M.; You, H.; Melendres, C.A.

1992-08-25

An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90[degree] in either direction while maintaining the working and counter electrodes submerged in the electrolyte. 5 figs.

Electrochemical cell

DOEpatents

Nagy, Zoltan; Yonco, Robert M.; You, Hoydoo; Melendres, Carlos A.

1992-01-01

An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90.degree. in either direction while maintaining the working and counter electrodes submerged in the electrolyte.

Recycling-oriented characterization of plastic frames and printed circuit boards from mobile phones by electronic and chemical imaging.

PubMed

Palmieri, Roberta; Bonifazi, Giuseppe; Serranti, Silvia

2014-11-01

This study characterizes the composition of plastic frames and printed circuit boards from end-of-life mobile phones. This knowledge may help define an optimal processing strategy for using these items as potential raw materials. Correct handling of such a waste is essential for its further "sustainable" recovery, especially to maximize the extraction of base, rare and precious metals, minimizing the environmental impact of the entire process chain. A combination of electronic and chemical imaging techniques was thus examined, applied and critically evaluated in order to optimize the processing, through the identification and the topological assessment of the materials of interest and their quantitative distribution. To reach this goal, end-of-life mobile phone derived wastes have been systematically characterized adopting both "traditional" (e.g. scanning electronic microscopy combined with microanalysis and Raman spectroscopy) and innovative (e.g. hyperspectral imaging in short wave infrared field) techniques, with reference to frames and printed circuit boards. Results showed as the combination of both the approaches (i.e. traditional and classical) could dramatically improve recycling strategies set up, as well as final products recovery. Copyright © 2014 Elsevier Ltd. All rights reserved.

SU-G-BRA-02: Development of a Learning Based Block Matching Algorithm for Ultrasound Tracking in Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shepard, A; Bednarz, B

Purpose: To develop an ultrasound learning-based tracking algorithm with the potential to provide real-time motion traces of anatomy-based fiducials that may aid in the effective delivery of external beam radiation. Methods: The algorithm was developed in Matlab R2015a and consists of two main stages: reference frame selection, and localized block matching. Immediately following frame acquisition, a normalized cross-correlation (NCC) similarity metric is used to determine a reference frame most similar to the current frame from a series of training set images that were acquired during a pretreatment scan. Segmented features in the reference frame provide the basis for the localizedmore » block matching to determine the feature locations in the current frame. The boundary points of the reference frame segmentation are used as the initial locations for the block matching and NCC is used to find the most similar block in the current frame. The best matched block locations in the current frame comprise the updated feature boundary. The algorithm was tested using five features from two sets of ultrasound patient data obtained from MICCAI 2014 CLUST. Due to the lack of a training set associated with the image sequences, the first 200 frames of the image sets were considered a valid training set for preliminary testing, and tracking was performed over the remaining frames. Results: Tracking of the five vessel features resulted in an average tracking error of 1.21 mm relative to predefined annotations. The average analysis rate was 15.7 FPS with analysis for one of the two patients reaching real-time speeds. Computations were performed on an i5-3230M at 2.60 GHz. Conclusion: Preliminary tests show tracking errors comparable with similar algorithms at close to real-time speeds. Extension of the work onto a GPU platform has the potential to achieve real-time performance, making tracking for therapy applications a feasible option. This work is partially funded by NIH grant R01CA190298.« less

Integrated GNSS Attitude Determination and Positioning for Direct Geo-Referencing

PubMed Central

Nadarajah, Nandakumaran; Paffenholz, Jens-André; Teunissen, Peter J. G.

2014-01-01

Direct geo-referencing is an efficient methodology for the fast acquisition of 3D spatial data. It requires the fusion of spatial data acquisition sensors with navigation sensors, such as Global Navigation Satellite System (GNSS) receivers. In this contribution, we consider an integrated GNSS navigation system to provide estimates of the position and attitude (orientation) of a 3D laser scanner. The proposed multi-sensor system (MSS) consists of multiple GNSS antennas rigidly mounted on the frame of a rotating laser scanner and a reference GNSS station with known coordinates. Precise GNSS navigation requires the resolution of the carrier phase ambiguities. The proposed method uses the multivariate constrained integer least-squares (MC-LAMBDA) method for the estimation of rotating frame ambiguities and attitude angles. MC-LAMBDA makes use of the known antenna geometry to strengthen the underlying attitude model and, hence, to enhance the reliability of rotating frame ambiguity resolution and attitude determination. The reliable estimation of rotating frame ambiguities is consequently utilized to enhance the relative positioning of the rotating frame with respect to the reference station. This integrated (array-aided) method improves ambiguity resolution, as well as positioning accuracy between the rotating frame and the reference station. Numerical analyses of GNSS data from a real-data campaign confirm the improved performance of the proposed method over the existing method. In particular, the integrated method yields reliable ambiguity resolution and reduces position standard deviation by a factor of about 0.8, matching the theoretical gain of 3/4 for two antennas on the rotating frame and a single antenna at the reference station. PMID:25036330

Integrated GNSS attitude determination and positioning for direct geo-referencing.

PubMed

Nadarajah, Nandakumaran; Paffenholz, Jens-André; Teunissen, Peter J G

2014-07-17

Direct geo-referencing is an efficient methodology for the fast acquisition of 3D spatial data. It requires the fusion of spatial data acquisition sensors with navigation sensors, such as Global Navigation Satellite System (GNSS) receivers. In this contribution, we consider an integrated GNSS navigation system to provide estimates of the position and attitude (orientation) of a 3D laser scanner. The proposed multi-sensor system (MSS) consists of multiple GNSS antennas rigidly mounted on the frame of a rotating laser scanner and a reference GNSS station with known coordinates. Precise GNSS navigation requires the resolution of the carrier phase ambiguities. The proposed method uses the multivariate constrained integer least-squares (MC-LAMBDA) method for the estimation of rotating frame ambiguities and attitude angles. MC-LAMBDA makes use of the known antenna geometry to strengthen the underlying attitude model and, hence, to enhance the reliability of rotating frame ambiguity resolution and attitude determination. The reliable estimation of rotating frame ambiguities is consequently utilized to enhance the relative positioning of the rotating frame with respect to the reference station. This integrated (array-aided) method improves ambiguity resolution, as well as positioning accuracy between the rotating frame and the reference station. Numerical analyses of GNSS data from a real-data campaign confirm the improved performance of the proposed method over the existing method. In particular, the integrated method yields reliable ambiguity resolution and reduces position standard deviation by a factor of about 0:8, matching the theoretical gain of √ 3/4 for two antennas on the rotating frame and a single antenna at the reference station.

Developmental vision determines the reference frame for the multisensory control of action.

PubMed

Röder, Brigitte; Kusmierek, Anna; Spence, Charles; Schicke, Tobias

2007-03-13

Both animal and human studies suggest that action goals are defined in external coordinates regardless of their sensory modality. The present study used an auditory-manual task to test whether the default use of such an external reference frame is innately determined or instead acquired during development because of the increasing dominance of vision over manual control. In Experiment I, congenitally blind, late blind, and age-matched sighted adults had to press a left or right response key depending on the bandwidth of pink noise bursts presented from either the left or right loudspeaker. Although the spatial location of the sounds was entirely task-irrelevant, all groups responded more efficiently with uncrossed hands when the sound was presented from the same side as the responding hand ("Simon effect"). This effect reversed with crossed hands only in the congenitally blind: They responded faster with the hand that was located contralateral to the sound source. In Experiment II, the instruction to the participants was changed: They now had to respond with the hand located next to the sound source. In contrast to Experiment I ("Simon-task"), this task required an explicit matching of the sound's location with the position of the responding hand. In Experiment II, the congenitally blind participants showed a significantly larger crossing deficit than both the sighted and late blind adults. This pattern of results implies that developmental vision induces the default use of an external coordinate frame for multisensory action control; this facilitates not only visual but also auditory-manual control.

Automatic Calibration of an Airborne Imaging System to an Inertial Navigation Unit

NASA Technical Reports Server (NTRS)

Ansar, Adnan I.; Clouse, Daniel S.; McHenry, Michael C.; Zarzhitsky, Dimitri V.; Pagdett, Curtis W.

2013-01-01

This software automatically calibrates a camera or an imaging array to an inertial navigation system (INS) that is rigidly mounted to the array or imager. In effect, it recovers the coordinate frame transformation between the reference frame of the imager and the reference frame of the INS. This innovation can automatically derive the camera-to-INS alignment using image data only. The assumption is that the camera fixates on an area while the aircraft flies on orbit. The system then, fully automatically, solves for the camera orientation in the INS frame. No manual intervention or ground tie point data is required.

Varieties of virtualization

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.

1991-01-01

Natural environments have a content, i.e., the objects in them; a geometry, i.e., a pattern of rules for positioning and displacing the objects; and a dynamics, i.e., a system of rules describing the effects of forces acting on the objects. Human interaction with most common natural environments has been optimized by centuries of evolution. Virtual environments created through the human-computer interface similarly have a content, geometry, and dynamics, but the arbitrary character of the computer simulation creating them does not insure that human interaction with these virtual environments will be natural. The interaction, indeed, could be supernatural but it also could be impossible. An important determinant of the comprehensibility of a virtual environment is the correspondence between the environmental frames of reference and those associated with the control of environmental objects. The effects of rotation and displacement of control frames of reference with respect to corresponding environmental references differ depending upon whether perceptual judgement or manual tracking performance is measured. The perceptual effects of frame of reference displacement may be analyzed in terms of distortions in the process of virtualizing the synthetic environment space. The effects of frame of reference displacement and rotation have been studied by asking subjects to estimate exocentric direction in a virtual space.

Gravity in the Brain as a Reference for Space and Time Perception.

PubMed

Lacquaniti, Francesco; Bosco, Gianfranco; Gravano, Silvio; Indovina, Iole; La Scaleia, Barbara; Maffei, Vincenzo; Zago, Myrka

2015-01-01

Moving and interacting with the environment require a reference for orientation and a scale for calibration in space and time. There is a wide variety of environmental clues and calibrated frames at different locales, but the reference of gravity is ubiquitous on Earth. The pull of gravity on static objects provides a plummet which, together with the horizontal plane, defines a three-dimensional Cartesian frame for visual images. On the other hand, the gravitational acceleration of falling objects can provide a time-stamp on events, because the motion duration of an object accelerated by gravity over a given path is fixed. Indeed, since ancient times, man has been using plumb bobs for spatial surveying, and water clocks or pendulum clocks for time keeping. Here we review behavioral evidence in favor of the hypothesis that the brain is endowed with mechanisms that exploit the presence of gravity to estimate the spatial orientation and the passage of time. Several visual and non-visual (vestibular, haptic, visceral) cues are merged to estimate the orientation of the visual vertical. However, the relative weight of each cue is not fixed, but depends on the specific task. Next, we show that an internal model of the effects of gravity is combined with multisensory signals to time the interception of falling objects, to time the passage through spatial landmarks during virtual navigation, to assess the duration of a gravitational motion, and to judge the naturalness of periodic motion under gravity.

Verification of the Polish Geodetic Reference Frame by Means of a New Solution Based on Permanent GNSS Data from the Years 2011-2014

NASA Astrophysics Data System (ADS)

Liwosz, T.; Ryczywolski, M.

2016-12-01

The new solution for the Polish geodetic primary GNSS network was created to verify the currently used reference frame (PL-ETRF2000). The new solution is based on more GNSS data (more daily observation sessions included, a longer data timespan, GLONASS observations added) which were processed in a newer reference frame (IGb08) according to up-to-date methodology and using the latest version of Bernese GNSS Software. The new long-term solution (spanning 3.7 years) was aligned to the IGb08 reference frame using a minimum constraints approach. We categorized Polish reference stations into two categories according to their data length. We obtained good agreement of the new solution with the PL-ETRF2000: for most stations position differences did not exceed 5 mm in horizontal, and 10 mm in vertical components. However, for 30 stations we observed discontinuities in position time series, mostly due to GNSS equipment changes, which occured after the introduction of PL-ETRF2000. Position changes due to the discontinuities reached 9.1 mm in horizontal components, and 26.9 mm in vertical components. The new solution takes into account position discontinuities, and in addition also includes six new stations which were installed after the introduction of the PL-ETRF2000. Therefore, we propose to update the currently-used reference frame for the Polish geodetic primary network (PL-ETRF2000) with the new solution. The new solution was also accepted by the EUREF Technical Working Group as a class A solution (highest accuracy) according to EUREF standards.

[Effects of frame of reference on the judgments of whole-body vibration intensity].

PubMed

Suzuki, H

1997-02-01

Although the concept of the term 'riding comfort' is ambiguous, in the present paper it means a perceptual experience derived from the vibrational factors of a running railway vehicle. When we regard riding comfort evaluation as a perceptual judgment process, we must consider that what is perceived is dependent not only on the physical properties of the stimuli, but also on the frame of reference. The purpose of the present study is to examine the effect of the frame on the judgments of vibration intensity in the anchoring effect paradigm. Using the four-axis vibration apparatus, we conducted experiments for eighty subjects, in which frequencies and lateral accelerations of vibrations were changed. As the result, we found a clear anchoring effect. This suggests that we must take into consideration effects of frame of reference in terms of riding comfort criterion of railway vehicles.

Innovative approach for in-vivo ablation validation on multimodal images

NASA Astrophysics Data System (ADS)

Shahin, O.; Karagkounis, G.; Carnegie, D.; Schlaefer, A.; Boctor, E.

2014-03-01

Radiofrequency ablation (RFA) is an important therapeutic procedure for small hepatic tumors. To make sure that the target tumor is effectively treated, RFA monitoring is essential. While several imaging modalities can observe the ablation procedure, it is not clear how ablated lesions on the images correspond to actual necroses. This uncertainty contributes to the high local recurrence rates (up to 55%) after radiofrequency ablative therapy. This study investigates a novel approach to correlate images of ablated lesions with actual necroses. We mapped both intraoperative images of the lesion and a slice through the actual necrosis in a common reference frame. An electromagnetic tracking system was used to accurately match lesion slices from different imaging modalities. To minimize the liver deformation effect, the tracking reference frame was defined inside the tissue by anchoring an electromagnetic sensor adjacent to the lesion. A validation test was performed using a phantom and proved that the end-to-end accuracy of the approach was within 2mm. In an in-vivo experiment, intraoperative magnetic resonance imaging (MRI) and ultrasound (US) ablation images were correlated to gross and histopathology. The results indicate that the proposed method can accurately correlate invivo ablations on different modalities. Ultimately, this will improve the interpretation of the ablation monitoring and reduce the recurrence rates associated with RFA.

Potential Refinement of the ICRF

NASA Technical Reports Server (NTRS)

Ma, Chopo

2003-01-01

The analysis and data used for the ICRF represented the state of the art in global, extragalactic, X/S band microwave astrometry in 1995. The same general analysis method was used to extend the ICRF with subsequent VLBI data in a manner consistent with the original catalog. Since 1995 there have been considerable advances in the geodetic/astrometric VLBI data set and in the analysis that would significantly improve the systematic errors, stability, and density of the next realization of the ICRS when the decision is made to take this step. In particular, data acquired since 1990, including extensive use of the VLBA, are of higher quality and astrometric utility because of changes in instrumentation, schedule design, and networks as well as specifically astrometric intent. The IVS (International VLBI Service for Geodesy and Astrometry) continues to devote a portion of its observing capability to systematic extension of the astrometric data set. Sufficient data distribution exists to select a better set of defining sources. Improvements in troposphere modeling will minimize known systematic astrometric errors while accurate modeling and estimation of station effects from loading and nonlinear motions will permit the reintegration of the celestial reference frame, terrestrial reference frame and Earth orientation parameters though a single VLBI solution. The differences between the current ICRF and the potential next realization will be described.

On the Persistent Shape and Coherence of Pulsating Auroral Patches

NASA Astrophysics Data System (ADS)

Humberset, B. K.; Gjerloev, J. W.; Mann, I. R.; Michell, R. G.; Samara, M.

2018-05-01

The pulsating aurora covers a broad range of fluctuating shapes that are poorly characterized. The purpose of this paper is therefore to provide objective and quantitative measures of the extent to which pulsating auroral patches maintain their shape, drift and fluctuate in a coherent fashion. We present results from a careful analysis of pulsating auroral patches using all-sky cameras. We have identified four well-defined individual patches that we follow in the patch frame of reference. In this way we avoid the space-time ambiguity which complicates rocket and satellite measurements. We find that the shape of the patches is remarkably persistent with 85-100% of the patch being repeated for 4.5-8.5 min. Each of the three largest patches has a temporal correlation with a negative dependence on distance, and thus does not fluctuate in a coherent fashion. A time-delayed response within the patches indicates that the so-called streaming mode might explain the incoherency. The patches appear to drift differently from the SuperDARN-determined E→×B→ convection velocity. However, in a nonrotating reference frame the patches drift with 230-287 m/s in a north eastward direction, which is what typically could be expected for the convection return flow.

Formulation of blade-flutter spectral analyses in stationary reference frame

NASA Technical Reports Server (NTRS)

Kurkov, A. P.

1984-01-01

Analytic representations are developed for the discrete blade deflection and the continuous tip static pressure fields in a stationary reference frame. Considered are the sampling rates equal to the rotational frequency, equal to blade passing frequency, and for the pressure, equal to a multiple of the blade passing frequency. For the last two rates the expressions for determining the nodal diameters from the spectra are included. A procedure is presented for transforming the complete unsteady pressure field into a rotating frame of reference. The determination of the true flutter frequency by using two sensors is described. To illustrate their use, the developed procedures are used to interpret selected experimental results.

Noninertial Multirelativity

NASA Astrophysics Data System (ADS)

Smarandache, Florentin

2012-10-01

We firstly propose an extension of Einstein's thought experiment with atomic clocks of the Special Theory of Relativity: considering non-constant accelerations and arbitrary 3D-curves for both a particle's speed and trajectory inside the rocket and respectively the rocket's speed and trajectory. And secondly we propose as research multiple reference frames F1, F2, , Fn moving on respectively arbitrary 3D-curves C1, C2, , Cn with respectively arbitrary non-constant accelerations a1, a2, , an and respectively initial velocities v1, v2, , vn. The reference frame Fi is moving with a nonconstant acceleration ai and initial velocity vi on a 3D-curve Ci with respect to another reference frame Fi+1 (where 1 <= i <= n-1).

Multiple Strategies for Spatial Integration of 2D Layouts within Working Memory

PubMed Central

Meilinger, Tobias; Watanabe, Katsumi

2016-01-01

Prior results on the spatial integration of layouts within a room differed regarding the reference frame that participants used for integration. We asked whether these differences also occur when integrating 2D screen views and, if so, what the reasons for this might be. In four experiments we showed that integrating reference frames varied as a function of task familiarity combined with processing time, cues for spatial transformation, and information about action requirements paralleling results in the 3D case. Participants saw part of an object layout in screen 1, another part in screen 2, and reacted on the integrated layout in screen 3. Layout presentations between two screens coincided or differed in orientation. Aligning misaligned screens for integration is known to increase errors/latencies. The error/latency pattern was thus indicative of the reference frame used for integration. We showed that task familiarity combined with self-paced learning, visual updating, and knowing from where to act prioritized the integration within the reference frame of the initial presentation, which was updated later, and from where participants acted respectively. Participants also heavily relied on layout intrinsic frames. The results show how humans flexibly adjust their integration strategy to a wide variety of conditions. PMID:27101011

A Ka-Band Celestial Reference Frame with Applications to Deep Space Navigation

NASA Technical Reports Server (NTRS)

Jacobs, Christopher S.; Clark, J. Eric; Garcia-Miro, Cristina; Horiuchi, Shinji; Sotuela, Ioana

2011-01-01

The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of approximately 200 micro-arcsec in alpha cos(delta) and approximately 300 micro-arcsec in delta. There is evidence for systematic errors at the 100 micro-arcsec level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.

Mission Capability Gains from Multi-Mode Propulsion Thrust Profile Variations for a Plane Change Maneuver

DTIC Science & Technology

2010-12-29

propellant mass [kg] msc = mass of the spacecraft [kg] MMP = multi-mode propulsion   = position in the Geocentric Equatorial Reference...thrust burn time [s] Tsc = thrust of the spacecraft [N] = vector between current and final velocity vector   = velocity vector in the Geocentric ...Equatorial Reference Frame of spacecraft in intended orbit [km/s]   = velocity vector in the Geocentric Equatorial Reference Frame of spacecraft in

Contribution to defining a geodetic reference frame for Africa (AFREF): Geodynamics implications

NASA Astrophysics Data System (ADS)

Saria, Elifuraha E.

African Reference Frame (AFREF) is the proposed regional three-dimensional standard frame, which will be used to reference positions and velocities for geodetic sites in Africa and surrounding. This frame will play a crucial role in scientific application for example plate motion and crustal deformation studies, and also in mapping when it involves for example national boundary surveying, remote sensing, GIS, engineering projects and other development programs in Africa. To contribute to the definition of geodetic reference frame for Africa and provide the first continent-wide position/velocity solution for Africa, we processed and analyzed 16 years of GPS and 17 years of DORIS data at 133 GPS sites and 9 DORIS sites continuously operating geodetic sites in Africa and surroundings to describe the present-day kinematics of the Nubian and Somalian plates and constrain relative motions across the East African Rift. We use the resulting horizontal velocities to determine the level of rigidity of Nubia and updated a plate motion model for the East African Rift and revise the counter clockwise rotation of the Victoria plate and clockwise rotation of the Rovuma plate with respect to Nubia. The vertical velocity ranges from -2 to +2 mm/yr, close to their uncertainties with no clear geographical pattern. This study provides the first continent-wide position/velocity solution for Africa, expressed in International Terrestrial Reference Frame (ITRF2008), a contribution to the upcoming African Reference Frame (AFREF). In the next step we used the substantial increase in the geologic, geophysical and geodetic data in Africa to improve our understanding of the rift geometry and the block kinematics of the EAR. We determined the best-fit fault structure of the rift in terms of the locking depth and dip angle and use a block modeling approach where observed velocities are described as the contribution of rigid block rotation and strain accumulation on locked faults. Our results show a better fit with three sub-plates (Victoria, Rovuma and Lwandle) between the major plates Nubia and Somalia. We show that the earthquake slip vectors provide information that is consistent with the GPS velocities and significantly help reduce the uncertainties in plate angular velocity estimates. However, we find that 3.16 My average spreading rates along the Southwest Indian Ridge (SWIR) from MORVEL model are systematically faster than GPS-derived motions across that ridge, possibly reflecting the need to revise the MORVEL outward displacement correction. In the final step, we attempt to understand the hydrological loading in Africa, which may affect our geodetic estimates, particularly the uplift rates. In this work, we analyze 10 years (2002 - 2012) of continuous GPS measurements operating in Africa, and compare with the modeled hydrological loading deformation inferred from the Gravity Recovery and Climate Experiment (GRACE) at the same GPS location and for the same time period. We estimated hydrological loading deformation based on the Equivalent Water Height (EWH) derived from the 10-days interval reprocessed GRACE solution second release (RL02). We took in to account in both GPS and GRACE the systematic errors from atmospheric pressure and non-tidal ocean loading effects and model the Earth as perfect elastic and compute the deformation using appropriate Greens function. We analyze the strength of association between the observation (GPS) and the model (GRACE) in terms of annual amplitude and phase as well as the original data (time-series). We find a good correlation mainly in regions associated with strong seasonal hydrological variations. To improve the correlation between the two solutions, we subtract the GRACE-derived vertical displacement from GPS-observed time series and determine the variance reduction. Our solution shows average variance between the model and the observation reduced to ~40%. (Abstract shortened by UMI.)

Analysis of the Motion Control Methods for Stratospheric Balloon-Borne Gondola Platform

NASA Astrophysics Data System (ADS)

Wang, H. H.; Yuan, Z. H.; Wu, J.

2006-10-01

At present, gondola platform is one of the stratospheric balloon-borne platforms being in research focus at home and overseas. Comparing to other stratospheric balloon-borne platforms, such as airship platform, gondola platform has advantages of higher stability, rapid in motion regulation and lower energy cost but disadvantages of less supporting capacity and be incapable of fixation. While all platforms have the same goal of keeping them at accurate angle and right pose for the requirements of instruments and objects installed in the platforms, when platforms rotate round the ground level perpendicular. That is accomplishing motion control. But, platform control system has factors of low damper, excessive and uncertain disturbances by the reason of its being hung over balloon in the air, it is hard to achieve the desired control precision because platform is ease to deviate its benchmark motion. Thus, in the controlling procedure in order to get higher precision, it is crucial to perceive the platform's swing synchronously and rapidly, and restrain the influence of disturbances effectively, keep the platform's pose steadily. Furthermore, while the platform in the air regard control center in the ground as reference object, it is ultimate to select a appropriate reference frame and work out the coordinates and implement the adjustment by the PC104 controller. This paper introduces the methods of the motion control based on stratospheric balloon-borne gondola platform. Firstly, this paper compares the characteristic of the flywheel and CMG and specifies the key methods of obtaining two significant states which are 'orientation stability' state and 'orientation tracking' state for platform motion control procedure using CMG as the control actuator. These two states reduce the deviation amplitude of rotation and swing of gondola's motion relative to original motion due to stratospheric intense atmosphere disturbance. We define it as the first procedure. In next procedure, we use the transfer matrix of earth reference frame to geographic reference frame to transform the data measured by the magnetic orientation sensors and the gyroscope to the space orientations, then the PC104 controller use the space orientations value as feedback to complete revises.

Three questions you need to ask about your brand.

PubMed

Keller, Kevin Lane; Sternthal, Brian; Tybout, Alice

2002-09-01

Traditionally, the people responsible for positioning brands have concentrated on the differences that set each brand apart from the competition. But emphasizing differences isn't enough to sustain a brand against competitors. Managers should also consider the frame of reference within which the brand works and the features the brand shares with other products. Asking three questions about your brand can help: HAVE WE ESTABLISHED A FRAME?: A frame of reference--for Coke, it might be as narrow as other colas or as broad as all thirst-quenching drinks--signals to consumers the goal they can expect to achieve by using a brand. Brand managers need to pay close attention to this issue, in some cases expanding their focus in order to preempt the competition. ARE WE LEVERAGING OUR POINTS OF PARITY?: Certain points of parity must be met if consumers are to perceive your product as a legitimate player within its frame of reference. For instance, consumers might not consider a bank truly a bank unless it offers checking and savings plans. ARE THE POINTS OF DIFFERENCE COMPELLING?: A distinguishing characteristic that consumers find both relevant and believable can become a strong, favorable, unique brand association, capable of distinguishing the brand from others in the same frame of reference. Frames of reference, points of parity, and points of difference are moving targets. Maytag isn't the only dependable brand of appliance, Tide isn't the only detergent with whitening power, and BMWs aren't the only cars on the road with superior handling. The key questions you need to ask about your brand may not change, but their context certainly will. The saviest brand positioners are also the most vigilant.

Effects of a rater training on rating accuracy in a physical examination skills assessment

PubMed Central

Weitz, Gunther; Vinzentius, Christian; Twesten, Christoph; Lehnert, Hendrik; Bonnemeier, Hendrik; König, Inke R.

2014-01-01

Background: The accuracy and reproducibility of medical skills assessment is generally low. Rater training has little or no effect. Our knowledge in this field, however, relies on studies involving video ratings of overall clinical performances. We hypothesised that a rater training focussing on the frame of reference could improve accuracy in grading the curricular assessment of a highly standardised physical head-to-toe examination. Methods: Twenty-one raters assessed the performance of 242 third-year medical students. Eleven raters had been randomly assigned to undergo a brief frame-of-reference training a few days before the assessment. 218 encounters were successfully recorded on video and re-assessed independently by three additional observers. Accuracy was defined as the concordance between the raters' grade and the median of the observers' grade. After the assessment, both students and raters filled in a questionnaire about their views on the assessment. Results: Rater training did not have a measurable influence on accuracy. However, trained raters rated significantly more stringently than untrained raters, and their overall stringency was closer to the stringency of the observers. The questionnaire indicated a higher awareness of the halo effect in the trained raters group. Although the self-assessment of the students mirrored the assessment of the raters in both groups, the students assessed by trained raters felt more discontent with their grade. Conclusions: While training had some marginal effects, it failed to have an impact on the individual accuracy. These results in real-life encounters are consistent with previous studies on rater training using video assessments of clinical performances. The high degree of standardisation in this study was not suitable to harmonize the trained raters’ grading. The data support the notion that the process of appraising medical performance is highly individual. A frame-of-reference training as applied does not effectively adjust the physicians' judgement on medical students in real-live assessments. PMID:25489341

Effects of a rater training on rating accuracy in a physical examination skills assessment.

PubMed

Weitz, Gunther; Vinzentius, Christian; Twesten, Christoph; Lehnert, Hendrik; Bonnemeier, Hendrik; König, Inke R

2014-01-01

The accuracy and reproducibility of medical skills assessment is generally low. Rater training has little or no effect. Our knowledge in this field, however, relies on studies involving video ratings of overall clinical performances. We hypothesised that a rater training focussing on the frame of reference could improve accuracy in grading the curricular assessment of a highly standardised physical head-to-toe examination. Twenty-one raters assessed the performance of 242 third-year medical students. Eleven raters had been randomly assigned to undergo a brief frame-of-reference training a few days before the assessment. 218 encounters were successfully recorded on video and re-assessed independently by three additional observers. Accuracy was defined as the concordance between the raters' grade and the median of the observers' grade. After the assessment, both students and raters filled in a questionnaire about their views on the assessment. Rater training did not have a measurable influence on accuracy. However, trained raters rated significantly more stringently than untrained raters, and their overall stringency was closer to the stringency of the observers. The questionnaire indicated a higher awareness of the halo effect in the trained raters group. Although the self-assessment of the students mirrored the assessment of the raters in both groups, the students assessed by trained raters felt more discontent with their grade. While training had some marginal effects, it failed to have an impact on the individual accuracy. These results in real-life encounters are consistent with previous studies on rater training using video assessments of clinical performances. The high degree of standardisation in this study was not suitable to harmonize the trained raters' grading. The data support the notion that the process of appraising medical performance is highly individual. A frame-of-reference training as applied does not effectively adjust the physicians' judgement on medical students in real-live assessments.

Motion of a Point Mass in a Rotating Disc: A Quantitative Analysis of the Coriolis and Centrifugal Force

NASA Astrophysics Data System (ADS)

Haddout, Soufiane

2016-06-01

In Newtonian mechanics, the non-inertial reference frames is a generalization of Newton's laws to any reference frames. While this approach simplifies some problems, there is often little physical insight into the motion, in particular into the effects of the Coriolis force. The fictitious Coriolis force can be used by anyone in that frame of reference to explain why objects follow curved paths. In this paper, a mathematical solution based on differential equations in non-inertial reference is used to study different types of motion in rotating system. In addition, the experimental data measured on a turntable device, using a video camera in a mechanics laboratory was conducted to compare with mathematical solution in case of parabolically curved, solving non-linear least-squares problems, based on Levenberg-Marquardt's and Gauss-Newton algorithms.

Reference Frames during the Acquisition and Development of Spatial Memories

ERIC Educational Resources Information Center

Kelly, Jonathan W.; McNamara, Timothy P.

2010-01-01

Four experiments investigated the role of reference frames during the acquisition and development of spatial knowledge, when learning occurs incrementally across views. In two experiments, participants learned overlapping spatial layouts. Layout 1 was first studied in isolation, and Layout 2 was later studied in the presence of Layout 1. The…

The Bernoulli Equation in a Moving Reference Frame

ERIC Educational Resources Information Center

Mungan, Carl E.

2011-01-01

Unlike other standard equations in introductory classical mechanics, the Bernoulli equation is not Galilean invariant. The explanation is that, in a reference frame moving with respect to constrictions or obstacles, those surfaces do work on the fluid, constituting an extra term that needs to be included in the work-energy calculation. A…

Implications of an Absolute Simultaneity Theory for Cosmology and Universe Acceleration

PubMed Central

Kipreos, Edward T.

2014-01-01

An alternate Lorentz transformation, Absolute Lorentz Transformation (ALT), has similar kinematics to special relativity yet maintains absolute simultaneity in the context of a preferred reference frame. In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass. Applying this theoretical framework to cosmological data produces a scenario of universal time contraction in the past. In this scenario, past time contraction would be associated with increased levels of blueshifted light emissions from cosmological objects when viewed from our current perspective. The observation that distant Type Ia supernovae are dimmer than predicted by linear Hubble expansion currently provides the most direct evidence for an accelerating universe. Adjusting for the effects of time contraction on a redshift–distance modulus diagram produces a linear distribution of supernovae over the full redshift spectrum that is consistent with a non-accelerating universe. PMID:25536116

Speech and gesture in spatial language and cognition among the Yucatec Mayas.

PubMed

Le Guen, Olivier

2011-07-01

In previous analyses of the influence of language on cognition, speech has been the main channel examined. In studies conducted among Yucatec Mayas, efforts to determine the preferred frame of reference in use in this community have failed to reach an agreement (Bohnemeyer & Stolz, 2006; Levinson, 2003 vs. Le Guen, 2006, 2009). This paper argues for a multimodal analysis of language that encompasses gesture as well as speech, and shows that the preferred frame of reference in Yucatec Maya is only detectable through the analysis of co-speech gesture and not through speech alone. A series of experiments compares knowledge of the semantics of spatial terms, performance on nonlinguistic tasks and gestures produced by men and women. The results show a striking gender difference in the knowledge of the semantics of spatial terms, but an equal preference for a geocentric frame of reference in nonverbal tasks. In a localization task, participants used a variety of strategies in their speech, but they all exhibited a systematic preference for a geocentric frame of reference in their gestures. Copyright © 2011 Cognitive Science Society, Inc.

The consistency of the current conventional celestial and terrestrial reference frames and the conventional EOP series

NASA Astrophysics Data System (ADS)

Heinkelmann, R.; Belda-Palazon, S.; Ferrándiz, J.; Schuh, H.

2015-08-01

For applications in Earth sciences, navigation, and astronomy the celestial (ICRF) and terrestrial (ITRF) reference frames as well as the orientation among them, the Earth orientation parameters (EOP), have to be consistent at the level of 1 mm and 0.1 mm/yr (GGOS recommendations). We assess the effect of unmodelled geophysical signals in the regularized coordinates and the sensitivity with respect to different a priori EOP and celestial reference frames. The EOP are determined using the same VLBI data but with station coordinates fixed on different TRFs. The conclusion is that within the time span of data incorporated into ITRF2008 (Altamimi, et al., 2011) the ITRF2008 and the IERS 08 C04 are consistent. This consistency involves that non-linear station motion such as unmodelled geophysical signals partly affect the IERS 08 C04 EOP. There are small but not negligible inconsistencies between the conventional celestial reference frame, ICRF2 (Fey, et al., 2009), the ITRF2008 and the conventional EOP that are quantified by comparing VTRF2008 (Böckmann, et al., 2010) and ITRF2008.

Disentangling the Contribution of Spatial Reference Frames to Executive Functioning in Healthy and Pathological Aging: An Experimental Study with Virtual Reality.

PubMed

Serino, Silvia; Morganti, Francesca; Colombo, Desirée; Pedroli, Elisa; Cipresso, Pietro; Riva, Giuseppe

2018-06-01

A growing body of evidence pointed out that a decline in effectively using spatial reference frames for categorizing information occurs both in normal and pathological aging. Moreover, it is also known that executive deficits primarily characterize the cognitive profile of older individuals. Acknowledging this literature, the current study was aimed to specifically disentangle the contribution of the cognitive abilities related to the use of spatial reference frames to executive functioning in both healthy and pathological aging. 48 healthy elderly individuals and 52 elderly suffering from probable Alzheimer's Disease (AD) took part in the study. We exploited the potentiality of Virtual Reality to specifically measure the abilities in retrieving and syncing between different spatial reference frames, and then we administrated different neuropsychological tests for evaluating executive functions. Our results indicated that allocentric functions contributed significantly to the planning abilities, while syncing abilities influenced the attentional ones. The findings were discussed in terms of previous literature exploring relationships between cognitive deficits in the first phase of AD.

Implications of an absolute simultaneity theory for cosmology and universe acceleration.

PubMed

Kipreos, Edward T

2014-01-01

An alternate Lorentz transformation, Absolute Lorentz Transformation (ALT), has similar kinematics to special relativity yet maintains absolute simultaneity in the context of a preferred reference frame. In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass. Applying this theoretical framework to cosmological data produces a scenario of universal time contraction in the past. In this scenario, past time contraction would be associated with increased levels of blueshifted light emissions from cosmological objects when viewed from our current perspective. The observation that distant Type Ia supernovae are dimmer than predicted by linear Hubble expansion currently provides the most direct evidence for an accelerating universe. Adjusting for the effects of time contraction on a redshift-distance modulus diagram produces a linear distribution of supernovae over the full redshift spectrum that is consistent with a non-accelerating universe.

The role of language in suicide reporting: Investigating the influence of problematic suicide referents.

PubMed

Arendt, Florian; Scherr, Sebastian; Niederkrotenthaler, Thomas; Till, Benedikt

2018-02-14

Although suicide experts recommend using neutral suicide referents in news media reporting, this recommendation has not yet been tested empirically. This recommendation, based on the empirically yet untested assumption that problematic suicide referents carry meaning that is inappropriate from a prevention perspective, may lead to a different perspective on suicide, termed "framing effects." For example, in German-speaking countries, the neutral term Suizid (suicide) is recommended. Conversely, Freitod ("free death") and Selbstmord ("self-murder") convey associative meanings related to problematic concepts such as free will (Freitod) and crime/murder (Selbstmord), and are therefore not recommended. Using a web-based randomized controlled trial focused on German speakers (N = 451), we tested whether the news media's use of Suizid, Selbstmord, and Freitod elicits framing effects. Participants read identical news reports about suicide. Only the specific suicide referents varied depending on the experimental condition. Post-reading, participants wrote short summaries of the news reports, completed a word-fragment completion test and a questionnaire targeting suicide-related attitudes. We found that the news frame primed some frame-related concepts in the memory and also increased frame-related word choice. Importantly, we found that participants reading the free will-related Freitod frame showed greater attitudinal support for suicide among individuals suffering from incurable diseases. This study highlights the importance of how the news media write about suicide and supports the language recommendations put forward by suicide experts. Copyright © 2018 Elsevier Ltd. All rights reserved.

Not all memories are the same: Situational context influences spatial recall within one's city of residency.

PubMed

Meilinger, Tobias; Frankenstein, Julia; Simon, Nadine; Bülthoff, Heinrich H; Bresciani, Jean-Pierre

2016-02-01

Reference frames in spatial memory encoding have been examined intensively in recent years. However, their importance for recall has received considerably less attention. In the present study, passersby used tags to arrange a configuration map of prominent city center landmarks. It has been shown that such configurational knowledge is memorized within a north-up reference frame. However, participants adjusted their maps according to their body orientations. For example, when participants faced south, the maps were likely to face south-up. Participants also constructed maps along their location perspective-that is, the self-target direction. If, for instance, they were east of the represented area, their maps were oriented west-up. If the location perspective and body orientation were in opposite directions (i.e., if participants faced away from the city center), participants relied on location perspective. The results indicate that reference frames in spatial recall depend on the current situation rather than on the organization in long-term memory. These results cannot be explained by activation spread within a view graph, which had been used to explain similar results in the recall of city plazas. However, the results are consistent with forming and transforming a spatial image of nonvisible city locations from the current location. Furthermore, prior research has almost exclusively focused on body- and environment-based reference frames. The strong influence of location perspective in an everyday navigational context indicates that such a reference frame should be considered more often when examining human spatial cognition.

Defining the cortical visual systems: "what", "where", and "how"

NASA Technical Reports Server (NTRS)

Creem, S. H.; Proffitt, D. R.; Kaiser, M. K. (Principal Investigator)

2001-01-01

The visual system historically has been defined as consisting of at least two broad subsystems subserving object and spatial vision. These visual processing streams have been organized both structurally as two distinct pathways in the brain, and functionally for the types of tasks that they mediate. The classic definition by Ungerleider and Mishkin labeled a ventral "what" stream to process object information and a dorsal "where" stream to process spatial information. More recently, Goodale and Milner redefined the two visual systems with a focus on the different ways in which visual information is transformed for different goals. They relabeled the dorsal stream as a "how" system for transforming visual information using an egocentric frame of reference in preparation for direct action. This paper reviews recent research from psychophysics, neurophysiology, neuropsychology and neuroimaging to define the roles of the ventral and dorsal visual processing streams. We discuss a possible solution that allows for both "where" and "how" systems that are functionally and structurally organized within the posterior parietal lobe.

Importance of Baseline Specification in Evaluating Conservation Interventions and Achieving No Net Loss of Biodiversity

PubMed Central

Bull, J W; Gordon, A; Law, E A; Suttle, K B; Milner-Gulland, E J

2014-01-01

There is an urgent need to improve the evaluation of conservation interventions. This requires specifying an objective and a frame of reference from which to measure performance. Reference frames can be baselines (i.e., known biodiversity at a fixed point in history) or counterfactuals (i.e., a scenario that would have occurred without the intervention). Biodiversity offsets are interventions with the objective of no net loss of biodiversity (NNL). We used biodiversity offsets to analyze the effects of the choice of reference frame on whether interventions met stated objectives. We developed 2 models to investigate the implications of setting different frames of reference in regions subject to various biodiversity trends and anthropogenic impacts. First, a general analytic model evaluated offsets against a range of baseline and counterfactual specifications. Second, a simulation model then replicated these results with a complex real world case study: native grassland offsets in Melbourne, Australia. Both models showed that achieving NNL depended upon the interaction between reference frame and background biodiversity trends. With a baseline, offsets were less likely to achieve NNL where biodiversity was decreasing than where biodiversity was stable or increasing. With a no-development counterfactual, however, NNL was achievable only where biodiversity was declining. Otherwise, preventing development was better for biodiversity. Uncertainty about compliance was a stronger determinant of success than uncertainty in underlying biodiversity trends. When only development and offset locations were considered, offsets sometimes resulted in NNL, but not across an entire region. Choice of reference frame determined feasibility and effort required to attain objectives when designing and evaluating biodiversity offset schemes. We argue the choice is thus of fundamental importance for conservation policy. Our results shed light on situations in which biodiversity offsets may be an inappropriate policy instrument Importancia de la Especificación de Línea de Base en la Evaluación de Intervenciones de Conservación y la Obtención de Ninguna Pérdida Neta de la Biodiversidad PMID:24945031

Distortions in memory for visual displays

NASA Technical Reports Server (NTRS)

Tversky, Barbara

1989-01-01

Systematic errors in perception and memory present a challenge to theories of perception and memory and to applied psychologists interested in overcoming them as well. A number of systematic errors in memory for maps and graphs are reviewed, and they are accounted for by an analysis of the perceptual processing presumed to occur in comprehension of maps and graphs. Visual stimuli, like verbal stimuli, are organized in comprehension and memory. For visual stimuli, the organization is a consequence of perceptual processing, which is bottom-up or data-driven in its earlier stages, but top-down and affected by conceptual knowledge later on. Segregation of figure from ground is an early process, and figure recognition later; for both, symmetry is a rapidly detected and ecologically valid cue. Once isolated, figures are organized relative to one another and relative to a frame of reference. Both perceptual (e.g., salience) and conceptual factors (e.g., significance) seem likely to affect selection of a reference frame. Consistent with the analysis, subjects perceived and remembered curves in graphs and rivers in maps as more symmetric than they actually were. Symmetry, useful for detecting and recognizing figures, distorts map and graph figures alike. Top-down processes also seem to operate in that calling attention to the symmetry vs. asymmetry of a slightly asymmetric curve yielded memory errors in the direction of the description. Conceptual frame of reference effects were demonstrated in memory for lines embedded in graphs. In earlier work, the orientation of map figures was distorted in memory toward horizontal or vertical. In recent work, graph lines, but not map lines, were remembered as closer to an imaginary 45 deg line than they had been. Reference frames are determined by both perceptual and conceptual factors, leading to selection of the canonical axes as a reference frame in maps, but selection of the imaginary 45 deg as a reference frame in graphs.

Is it possible to predict long-term success with k-NN? Case study of four market indices (FTSE100, DAX, HANGSENG, NASDAQ)

NASA Astrophysics Data System (ADS)

Shi, Y.; Gorban, A. N.; Y Yang, T.

2014-03-01

This case study tests the possibility of prediction for 'success' (or 'winner') components of four stock & shares market indices in a time period of three years from 02-Jul-2009 to 29-Jun-2012.We compare their performance ain two time frames: initial frame three months at the beginning (02/06/2009-30/09/2009) and the final three month frame (02/04/2012-29/06/2012).To label the components, average price ratio between two time frames in descending order is computed. The average price ratio is defined as the ratio between the mean prices of the beginning and final time period. The 'winner' components are referred to the top one third of total components in the same order as average price ratio it means the mean price of final time period is relatively higher than the beginning time period. The 'loser' components are referred to the last one third of total components in the same order as they have higher mean prices of beginning time period. We analyse, is there any information about the winner-looser separation in the initial fragments of the daily closing prices log-returns time series.The Leave-One-Out Cross-Validation with k-NN algorithm is applied on the daily log-return of components using a distance and proximity in the experiment. By looking at the error analysis, it shows that for HANGSENG and DAX index, there are clear signs of possibility to evaluate the probability of long-term success. The correlation distance matrix histograms and 2-D/3-D elastic maps generated from ViDaExpert show that the 'winner' components are closer to each other and 'winner'/'loser' components are separable on elastic maps for HANGSENG and DAX index while for the negative possibility indices, there is no sign of separation.

Construction Theory and Noise Analysis Method of Global CGCS2000 Coordinate Frame

NASA Astrophysics Data System (ADS)

Jiang, Z.; Wang, F.; Bai, J.; Li, Z.

2018-04-01

The definition, renewal and maintenance of geodetic datum has been international hot issue. In recent years, many countries have been studying and implementing modernization and renewal of local geodetic reference coordinate frame. Based on the precise result of continuous observation for recent 15 years from state CORS (continuously operating reference system) network and the mainland GNSS (Global Navigation Satellite System) network between 1999 and 2007, this paper studies the construction of mathematical model of the Global CGCS2000 frame, mainly analyzes the theory and algorithm of two-step method for Global CGCS2000 Coordinate Frame formulation. Finally, the noise characteristic of the coordinate time series are estimated quantitatively with the criterion of maximum likelihood estimation.

Does Changing the Reference Frame Affect Infant Categorization of the Spatial Relation BETWEEN?

ERIC Educational Resources Information Center

Quinn, Paul C.; Doran, Matthew M.; Papafragou, Anna

2011-01-01

Past research has shown that variation in the target objects depicting a given spatial relation disrupts the formation of a category representation for that relation. In the current research, we asked whether changing the orientation of the referent frame depicting the spatial relation would also disrupt the formation of a category representation…

The Generalized Internal/External Frame of Reference Model: An Extension to Dimensional Comparison Theory

ERIC Educational Resources Information Center

Möller, Jens; Müller-Kalthoff, Hanno; Helm, Friederike; Nagy, Nicole; Marsh, Herb W.

2016-01-01

The dimensional comparison theory (DCT) focuses on the effects of internal, dimensional comparisons (e.g., "How good am I in math compared to English?") on academic self-concepts with widespread consequences for students' self-evaluation, motivation, and behavioral choices. DCT is based on the internal/external frame of reference model…

Cognitive Ability, Academic Achievement and Academic Self-Concept: Extending the Internal/External Frame of Reference Model

ERIC Educational Resources Information Center

Chen, Ssu-Kuang; Hwang, Fang-Ming; Yeh, Yu-Chen; Lin, Sunny S. J.

2012-01-01

Background: Marsh's internal/external (I/E) frame of reference model depicts the relationship between achievement and self-concept in specific academic domains. Few efforts have been made to examine concurrent relationships among cognitive ability, achievement, and academic self-concept (ASC) within an I/E model framework. Aim: To simultaneously…

The Role of Perspective Taking in How Children Connect Reference Frames When Explaining Astronomical Phenomena

ERIC Educational Resources Information Center

Plummer, Julia D.; Bower, Corinne A.; Liben, Lynn S.

2016-01-01

This study investigates the role of perspective-taking skills in how children explain spatially complex astronomical phenomena. Explaining many astronomical phenomena, especially those studied in elementary and middle school, requires shifting between an Earth-based description of the phenomena and a space-based reference frame. We studied 7- to…

Operationalization of a Frame of Reference for Studying Organizational Culture in Middle Schools.

ERIC Educational Resources Information Center

Daniel, Larry G.

A frame of reference for studying culture in middle schools was developed. Items for the Middle School Description Survey (MSDS), which was designed to test elements of the ideal middle school culture, were created based on middle school advocacy literature. The items were conceptually categorized according to E. H. Schein's (1985) cultural…

Facing the Sunrise: Cultural Worldview Underlying Intrinsic-Based Encoding of Absolute Frames of Reference in Aymara

ERIC Educational Resources Information Center

Nunez, Rafael E.; Cornejo, Carlos

2012-01-01

The Aymara of the Andes use absolute (cardinal) frames of reference for describing the relative position of ordinary objects. However, rather than encoding them in available absolute lexemes, they do it in lexemes that are intrinsic to the body: "nayra" ("front") and "qhipa" ("back"), denoting east and west,…

Mechanisms of Reference Frame Selection in Spatial Term Use: Computational and Empirical Studies

ERIC Educational Resources Information Center

Schultheis, Holger; Carlson, Laura A.

2017-01-01

Previous studies have shown that multiple reference frames are available and compete for selection during the use of spatial terms such as "above." However, the mechanisms that underlie the selection process are poorly understood. In the current paper we present two experiments and a comparison of three computational models of selection…

Frame of Reference Rater Training Issues: Recall, Time and Behavior Observation Training.

ERIC Educational Resources Information Center

Roch, Sylvia G.; O'Sullivan, Brian J.

2003-01-01

Graduate students were trained as raters either using frame of reference (FOR, n=220, behavior observation training (BOT, n=21), or performance appraisal (controls, n=21). They rated videotaped lecturers twice. FOR increased number of behaviors recalled; FOR and BOT improved recall quality. FOR improved rating accuracy even after 2 weeks.…

Myths, Misconceptions, and Misunderstandings: A Different Spin on Coriolis--Applying Frame of Reference

ERIC Educational Resources Information Center

DiSpezio, Michael A.

2011-01-01

This article addresses misconceptions surrounding the Coriolis force and describes how it should be presented as a function within inertial and noninertial frames of reference. Not only does this demonstrate the nature of science as it strives to best interpret the natural world (and presents alternative explanations), but it offers a rich…

Velocity Estimate Following Air Data System Failure

DTIC Science & Technology

2008-03-01

39 Figure 3.3. Sampled Two Vector Approach .................................................................... 40 Figure 3.4...algorithm design in terms of reference frames, equations of motion, and velocity triangles describing the vector relationship between airspeed, wind speed...2.2.1 Reference Frames The flight of an aircraft through the air mass can be described in specific coordinate systems [ Nelson 1998]. To determine how

iGRaND: an invariant frame for RGBD sensor feature detection and descriptor extraction with applications

NASA Astrophysics Data System (ADS)

Willis, Andrew R.; Brink, Kevin M.

2016-06-01

This article describes a new 3D RGBD image feature, referred to as iGRaND, for use in real-time systems that use these sensors for tracking, motion capture, or robotic vision applications. iGRaND features use a novel local reference frame derived from the image gradient and depth normal (hence iGRaND) that is invariant to scale and viewpoint for Lambertian surfaces. Using this reference frame, Euclidean invariant feature components are computed at keypoints which fuse local geometric shape information with surface appearance information. The performance of the feature for real-time odometry is analyzed and its computational complexity and accuracy is compared with leading alternative 3D features.

Laser-Camera Vision Sensing for Spacecraft Mobile Robot Navigation

NASA Technical Reports Server (NTRS)

Maluf, David A.; Khalil, Ahmad S.; Dorais, Gregory A.; Gawdiak, Yuri

2002-01-01

The advent of spacecraft mobile robots-free-flyng sensor platforms and communications devices intended to accompany astronauts or remotely operate on space missions both inside and outside of a spacecraft-has demanded the development of a simple and effective navigation schema. One such system under exploration involves the use of a laser-camera arrangement to predict relative positioning of the mobile robot. By projecting laser beams from the robot, a 3D reference frame can be introduced. Thus, as the robot shifts in position, the position reference frame produced by the laser images is correspondingly altered. Using normalization and camera registration techniques presented in this paper, the relative translation and rotation of the robot in 3D are determined from these reference frame transformations.

Optical monitoring of QSO in the framework of the Gaia space mission

NASA Astrophysics Data System (ADS)

Taris, F.; Damljanovic, G.; Andrei, A.; Klotz, A.; Vachier, F.

2015-08-01

The Gaia astrometric mission of the European Space Agency has been launched the 19th December 2013. It will provide an astrometric catalogue of 500 000 extragalactic sources that could be the basis of a new optical reference frame. On the other hand, the current International Celestial Reference Frame (ICRF) is based on the observations of extragalactic sources at radio wavelength. The astrometric coordinates of sources in these two reference systems will have roughly the same uncertainty. It is then mandatory to observe a set of common targets at both optical and radio wavelength to link the ICRF with what could be called the GCRF (Gaia Celestial Reference Frame). We will show in this paper some results obtained with the TJO, Telescopi Juan Oro, from Observatori Astronomic del Montsec in Spain. It also presents some results obtained with the Lomb-Scargle and CLEAN algorithm methods applied to optical magnitude obtained with the TAROT telescopes.

Reference Frames in Earth Rotation Theories

NASA Astrophysics Data System (ADS)

Ferrándiz, José M.; Belda, Santiago; Heinkelmann, Robert; Getino, Juan; Schuh, Harald; Escapa, Alberto

2015-04-01

Nowadays the determination of the Earth Orientation Parameters (EOP) and the different Terrestrial Reference Frames (TRF) are not independent. The available theories of Earth rotation aims at providing the orientation of a certain reference system linked somehow to the Earth with respect to a given celestial system, considered as inertial. In the past years a considerable effort has been dedicated to the improvement of the TRF realizations, following the lines set up in the 1980's. However, the reference systems used in the derivation of the theories have been rather considered as something fully established, not deserving a special attention. In this contribution we review the definitions of the frames used in the main theoretical approaches, focusing on those used in the construction of IAU2000, and the extent to which their underlying hypotheses hold. The results are useful to determine the level of consistency of the predicted and determined EOP.

Integrating Analysis Goals for EOP, CRF and TRF

NASA Technical Reports Server (NTRS)

Ma, Chopo; MacMillan, D.; Petrov, L.; Smith, David E. (Technical Monitor)

2001-01-01

In a simplified, idealized way the TRF can be considered a set of positions at epoch and corresponding linear rates of change while the CRF is a set of fixed directions in space. VLBI analysis can be optimized for CRF and TRF separately while handling some of the complexity of geodetic and astrometric reality. For EOP time series both CRF and TRF should be accurate at the epoch of interest and well defined over time. The optimal integral EOP, TRF and CRF in a single VLBI solution configuration requires a detailed consideration of the data set and the possibly conflicting nature of reference frames.

Report of the panel on international programs

NASA Technical Reports Server (NTRS)

Anderson, Allen Joel; Fuchs, Karl W.; Ganeka, Yasuhiro; Gaur, Vinod; Green, Andrew A.; Siegfried, W.; Lambert, Anthony; Rais, Jacub; Reighber, Christopher; Seeger, Herman

1991-01-01

The panel recommends that NASA participate and take an active role in the continuous monitoring of existing regional networks, the realization of high resolution geopotential and topographic missions, the establishment of interconnection of the reference frames as defined by different space techniques, the development and implementation of automation for all ground-to-space observing systems, calibration and validation experiments for measuring techniques and data, the establishment of international space-based networks for real-time transmission of high density space data in standardized formats, tracking and support for non-NASA missions, and the extension of state-of-the art observing and analysis techniques to developing nations.

Influence of the Pixel Sizes of Reference Computed Tomography on Single-photon Emission Computed Tomography Image Reconstruction Using Conjugate-gradient Algorithm.

PubMed

Okuda, Kyohei; Sakimoto, Shota; Fujii, Susumu; Ida, Tomonobu; Moriyama, Shigeru

The frame-of-reference using computed-tomography (CT) coordinate system on single-photon emission computed tomography (SPECT) reconstruction is one of the advanced characteristics of the xSPECT reconstruction system. The aim of this study was to reveal the influence of the high-resolution frame-of-reference on the xSPECT reconstruction. 99m Tc line-source phantom and National Electrical Manufacturers Association (NEMA) image quality phantom were scanned using the SPECT/CT system. xSPECT reconstructions were performed with the reference CT images in different sizes of the display field-of-view (DFOV) and pixel. The pixel sizes of the reconstructed xSPECT images were close to 2.4 mm, which is acquired as originally projection data, even if the reference CT resolution was varied. The full width at half maximum (FWHM) of the line-source, absolute recovery coefficient, and background variability of image quality phantom were independent on the sizes of DFOV in the reference CT images. The results of this study revealed that the image quality of the reconstructed xSPECT images is not influenced by the resolution of frame-of-reference on SPECT reconstruction.

Making Meaning Out of Text.

ERIC Educational Resources Information Center

Kathpalia, Sujata S.

2001-01-01

Investigates textual coherence of popular psychology articles mediated through the theory of frames and identifies the linguistic evidence of factual frames. Inferencing is also discussed as a supplementary means to comprehension, with particular reference to the notion of bridging assumptions. Evidence for textual frames is discussed in relation…

FOOT PLACEMENT IN A BODY REFERENCE FRAME DURING WALKING AND ITS RELATIONSHIP TO HEMIPARETIC WALKING PERFORMANCE

PubMed Central

Balasubramanian, Chitralakshmi K.; Neptune, Richard R.; Kautz, Steven A.

2010-01-01

Background Foot placement during walking is closely linked to the body position, yet it is typically quantified relative to the other foot. The purpose of this study was to quantify foot placement patterns relative to body post-stroke and investigate its relationship to hemiparetic walking performance. Methods Thirty-nine participants with hemiparesis walked on a split-belt treadmill at their self-selected speeds and twenty healthy participants walked at matched slow speeds. Anterior-posterior and medial-lateral foot placements (foot center-of-mass) relative to body (pelvis center-of-mass) quantified stepping in body reference frame. Walking performance was quantified using step length asymmetry ratio, percent of paretic propulsion and paretic weight support. Findings Participants with hemiparesis placed their paretic foot further anterior than posterior during walking compared to controls walking at matched slow speeds (p < .05). Participants also placed their paretic foot further lateral relative to pelvis than non-paretic (p < .05). Anterior-posterior asymmetry correlated with step length asymmetry and percent paretic propulsion but some persons revealed differing asymmetry patterns in the translating reference frame. Lateral foot placement asymmetry correlated with paretic weight support (r = .596; p < .001), whereas step widths showed no relation to paretic weight support. Interpretation Post-stroke gait is asymmetric when quantifying foot placement in a body reference frame and this asymmetry related to the hemiparetic walking performance and explained motor control mechanisms beyond those explained by step lengths and step widths alone. We suggest that biomechanical analyses quantifying stepping performance in impaired populations should investigate foot placement in a body reference frame. PMID:20193972

Foot placement in a body reference frame during walking and its relationship to hemiparetic walking performance.

PubMed

Balasubramanian, Chitralakshmi K; Neptune, Richard R; Kautz, Steven A

2010-06-01

Foot placement during walking is closely linked to the body position, yet it is typically quantified relative to the other foot. The purpose of this study was to quantify foot placement patterns relative to body post-stroke and investigate its relationship to hemiparetic walking performance. Thirty-nine participants with hemiparesis walked on a split-belt treadmill at their self-selected speeds and 20 healthy participants walked at matched slow speeds. Anterior-posterior and medial-lateral foot placements (foot center-of-mass) relative to body (pelvis center-of-mass) quantified stepping in body reference frame. Walking performance was quantified using step length asymmetry ratio, percent of paretic propulsion and paretic weight support. Participants with hemiparesis placed their paretic foot further anterior than posterior during walking compared to controls walking at matched slow speeds (P<.05). Participants also placed their paretic foot further lateral relative to pelvis than non-paretic (P<.05). Anterior-posterior asymmetry correlated with step length asymmetry and percent paretic propulsion but some persons revealed differing asymmetry patterns in the translating reference frame. Lateral foot placement asymmetry correlated with paretic weight support (r=.596; P<.001), whereas step widths showed no relation to paretic weight support. Post-stroke gait is asymmetric when quantifying foot placement in a body reference frame and this asymmetry related to the hemiparetic walking performance and explained motor control mechanisms beyond those explained by step lengths and step widths alone. We suggest that biomechanical analyses quantifying stepping performance in impaired populations should investigate foot placement in a body reference frame. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Unitary cocycle representations of the Galilean line group: Quantum mechanical principle of equivalence

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacGregor, B.R.; McCoy, A.E.; Wickramasekara, S., E-mail: wickrama@grinnell.edu

2012-09-15

We present a formalism of Galilean quantum mechanics in non-inertial reference frames and discuss its implications for the equivalence principle. This extension of quantum mechanics rests on the Galilean line group, the semidirect product of the real line and the group of analytic functions from the real line to the Euclidean group in three dimensions. This group provides transformations between all inertial and non-inertial reference frames and contains the Galilei group as a subgroup. We construct a certain class of unitary representations of the Galilean line group and show that these representations determine the structure of quantum mechanics in non-inertialmore » reference frames. Our representations of the Galilean line group contain the usual unitary projective representations of the Galilei group, but have a more intricate cocycle structure. The transformation formula for the Hamiltonian under the Galilean line group shows that in a non-inertial reference frame it acquires a fictitious potential energy term that is proportional to the inertial mass, suggesting the equivalence of inertial mass and gravitational mass in quantum mechanics. - Highlights: Black-Right-Pointing-Pointer A formulation of Galilean quantum mechanics in non-inertial reference frames is given. Black-Right-Pointing-Pointer The key concept is the Galilean line group, an infinite dimensional group. Black-Right-Pointing-Pointer Unitary, cocycle representations of the Galilean line group are constructed. Black-Right-Pointing-Pointer A non-central extension of the group underlies these representations. Black-Right-Pointing-Pointer Quantum equivalence principle and gravity emerge from these representations.« less

Simultaneous tracking and regulation visual servoing of wheeled mobile robots with uncalibrated extrinsic parameters

NASA Astrophysics Data System (ADS)

Lu, Qun; Yu, Li; Zhang, Dan; Zhang, Xuebo

2018-01-01

This paper presentsa global adaptive controller that simultaneously solves tracking and regulation for wheeled mobile robots with unknown depth and uncalibrated camera-to-robot extrinsic parameters. The rotational angle and the scaled translation between the current camera frame and the reference camera frame, as well as the ones between the desired camera frame and the reference camera frame can be calculated in real time by using the pose estimation techniques. A transformed system is first obtained, for which an adaptive controller is then designed to accomplish both tracking and regulation tasks, and the controller synthesis is based on Lyapunov's direct method. Finally, the effectiveness of the proposed method is illustrated by a simulation study.

When Students Doubt Their Teachers' Diagnostic Competence: Moderation in the Internal/External Frame of Reference Model

ERIC Educational Resources Information Center

Zimmermann, Friederike; Möller, Jens; Köller, Olaf

2018-01-01

The internal/external frame of reference model (I/E model) posits that individuals' achievement-related self-concepts are formed through social comparisons (e.g., self vs. peers) within academic domains and dimensional comparisons (e.g., math vs. verbal) between distinct domains. A large body of research has supported the theorized pattern of…

Antecedents of Academic Emotions: Testing the Internal/External Frame of Reference Model for Academic Enjoyment

ERIC Educational Resources Information Center

Goetz, Thomas; Frenzel, Anne C.; Hall, Nathan C.; Pekrun, Reinhard

2008-01-01

The present study focused on students' academic enjoyment as predicted by achievement in multiple academic domains. Assumptions were based on Marsh's internal/external (I/E) frame of reference model and Pekrun's control-value theory of achievement emotions, and were tested in a sample of 1380 German students from grades 5 to 10. Students' academic…

Learning to Explain Astronomy across Moving Frames of Reference: Exploring the Role of Classroom and Planetarium-Based Instructional Contexts

ERIC Educational Resources Information Center

Plummer, Julia Diane; Kocareli, Alicia; Slagle, Cynthia

2014-01-01

Learning astronomy involves significant spatial reasoning, such as learning to describe Earth-based phenomena and understanding space-based explanations for those phenomena as well as using the relevant size and scale information to interpret these frames of reference. This study examines daily celestial motion (DCM) as one case of how children…

Layout Geometry in the Selection of Intrinsic Frames of Reference from Multiple Viewpoints

ERIC Educational Resources Information Center

Mou, Weimin; Zhao, Mintao; McNamara, Timothy P.

2007-01-01

Four experiments investigated the roles of layout geometry in the selection of intrinsic frames of reference in spatial memory. Participants learned the locations of objects in a room from 2 or 3 viewing perspectives. One view corresponded to the axis of bilateral symmetry of the layout, and the other view(s) was (were) nonorthogonal to the axis…

Teachers' Interpretations of the Internet. An Applied Case Study for the Evaluation of Technological Frames of Reference

ERIC Educational Resources Information Center

Camilleri, Patrick

2012-01-01

In 1994 Orlikowski and Gash articulated Technological Frames of Reference as a systematic theoretical lens to examine technological developments in organisations. A decade later, in 2004, Davidson and Pai expressed concern that while the lens was widely cited in academic discourse, the incidence and adoption of the model as an analytical framework…

Does Environmental Experience Shape Spatial Cognition? Frames of Reference among Ancash Quechua Speakers (Peru)

ERIC Educational Resources Information Center

Shapero, Joshua A.

2017-01-01

Previous studies have shown that language contributes to humans' ability to orient using landmarks and shapes their use of frames of reference (FoRs) for memory. However, the role of environmental experience in shaping spatial cognition has not been investigated. This study addresses such a possibility by examining the use of FoRs in a nonverbal…

Justifying Alternative Models in Learning Astronomy: A Study of K-8 Science Teachers' Understanding of Frames of Reference

ERIC Educational Resources Information Center

Shen, Ji; Confrey, Jere

2010-01-01

Understanding frames of reference is critical in describing planetary motion and learning astronomy. Historically, the geocentric and heliocentric models were defended and advocated against each other. Today, there are still many people who do not understand the relationship between the two models. This topic is not adequately treated in astronomy…

The Reciprocal Internal/External Frame of Reference Model Using Grades and Test Scores

ERIC Educational Resources Information Center

Möller, Jens; Zimmermann, Friederike; Köller, Olaf

2014-01-01

Background: The reciprocal I/E model (RI/EM) combines the internal/external frame of reference model (I/EM) with the reciprocal effects model (REM). The RI/EM extends the I/EM longitudinally and the REM across domains. The model predicts that, within domains, mathematics and verbal achievement (VACH) and academic self-concept have positive effects…

New architecture for dynamic frame-skipping transcoder.

PubMed

Fung, Kai-Tat; Chan, Yui-Lam; Siu, Wan-Chi

2002-01-01

Transcoding is a key technique for reducing the bit rate of a previously compressed video signal. A high transcoding ratio may result in an unacceptable picture quality when the full frame rate of the incoming video bitstream is used. Frame skipping is often used as an efficient scheme to allocate more bits to the representative frames, so that an acceptable quality for each frame can be maintained. However, the skipped frame must be decompressed completely, which might act as a reference frame to nonskipped frames for reconstruction. The newly quantized discrete cosine transform (DCT) coefficients of the prediction errors need to be re-computed for the nonskipped frame with reference to the previous nonskipped frame; this can create undesirable complexity as well as introduce re-encoding errors. In this paper, we propose new algorithms and a novel architecture for frame-rate reduction to improve picture quality and to reduce complexity. The proposed architecture is mainly performed on the DCT domain to achieve a transcoder with low complexity. With the direct addition of DCT coefficients and an error compensation feedback loop, re-encoding errors are reduced significantly. Furthermore, we propose a frame-rate control scheme which can dynamically adjust the number of skipped frames according to the incoming motion vectors and re-encoding errors due to transcoding such that the decoded sequence can have a smooth motion as well as better transcoded pictures. Experimental results show that, as compared to the conventional transcoder, the new architecture for frame-skipping transcoder is more robust, produces fewer requantization errors, and has reduced computational complexity.

Photovoltaic module and module arrays

DOEpatents

Botkin, Jonathan; Graves, Simon; Lenox, Carl J. S.; Culligan, Matthew; Danning, Matt

2013-08-27

A photovoltaic (PV) module including a PV device and a frame, The PV device has a PV laminate defining a perimeter and a major plane. The frame is assembled to and encases the laminate perimeter, and includes leading, trailing, and side frame members, and an arm that forms a support face opposite the laminate. The support face is adapted for placement against a horizontal installation surface, to support and orient the laminate in a non-parallel or tilted arrangement. Upon final assembly, the laminate and the frame combine to define a unitary structure. The frame can orient the laminate at an angle in the range of 3.degree.-7.degree. from horizontal, and can be entirely formed of a polymeric material. Optionally, the arm incorporates integral feature(s) that facilitate interconnection with corresponding features of a second, identically formed PV module.

Photovoltaic module and module arrays

DOEpatents

Botkin, Jonathan [El Cerrito, CA; Graves, Simon [Berkeley, CA; Lenox, Carl J. S. [Oakland, CA; Culligan, Matthew [Berkeley, CA; Danning, Matt [Oakland, CA

2012-07-17

A photovoltaic (PV) module including a PV device and a frame. The PV device has a PV laminate defining a perimeter and a major plane. The frame is assembled to and encases the laminate perimeter, and includes leading, trailing, and side frame members, and an arm that forms a support face opposite the laminate. The support face is adapted for placement against a horizontal installation surface, to support and orient the laminate in a non-parallel or tilted arrangement. Upon final assembly, the laminate and the frame combine to define a unitary structure. The frame can orient the laminate at an angle in the range of 3.degree.-7.degree. from horizontal, and can be entirely formed of a polymeric material. Optionally, the arm incorporates integral feature(s) that facilitate interconnection with corresponding features of a second, identically formed PV module.

Autonomous orbital navigation using Kepler's equation

NASA Technical Reports Server (NTRS)

Boltz, F. W.

1974-01-01

A simple method of determining the six elements of elliptic satellite orbits has been developed for use aboard manned and unmanned spacecraft orbiting the earth, moon, or any planet. The system requires the use of a horizon sensor or other device for determining the local vertical, a precision clock or timing device, and Apollo-type navigation equipment including an inertial measurement unit (IMU), a digital computer, and a coupling data unit. The three elements defining the in-plane motion are obtained from simultaneous measurements of central angle traversed around the planet and elapsed flight time using a linearization of Kepler's equation about a reference orbit. It is shown how Kalman filter theory may also be used to determine the in-plane orbital elements. The three elements defining the orbit orientation are obtained from position angles in celestial coordinates derived from the IMU with the spacecraft vertically oriented after alignment of the IMU to a known inertial coordinate frame.

Text-Frame Relationships and ESL.

ERIC Educational Resources Information Center

Burquest, Donald A.; Henry, Floreen Barger

The relationship of contextual background to comprehension of written texts is discussed with reference to instruction in English as a second language (ESL). A theory advanced by Kerry Stewart Robichaux proposes six possible relationships between a text and its cultural "frame." Applications of the six text-frame relationships to foreign…

Realizing a terrestrial reference frame using the Global Positioning System

NASA Astrophysics Data System (ADS)

Haines, Bruce J.; Bar-Sever, Yoaz E.; Bertiger, Willy I.; Desai, Shailen D.; Harvey, Nate; Sibois, Aurore E.; Weiss, Jan P.

2015-08-01

We describe a terrestrial reference frame (TRF) realization based on Global Positioning System (GPS) data alone. Our approach rests on a highly dynamic, long-arc (9 day) estimation strategy and on GPS satellite antenna calibrations derived from Gravity Recovery and Climate Experiment and TOPEX/Poseidon low Earth orbit receiver GPS data. Based on nearly 17 years of data (1997-2013), our solution for scale rate agrees with International Terrestrial Reference Frame (ITRF)2008 to 0.03 ppb yr-1, and our solution for 3-D origin rate agrees with ITRF2008 to 0.4 mm yr-1. Absolute scale differs by 1.1 ppb (7 mm at the Earth's surface) and 3-D origin by 8 mm. These differences lie within estimated error levels for the contemporary TRF.

Proof-of-principle experiment of reference-frame-independent quantum key distribution with phase coding

PubMed Central

Liang, Wen-Ye; Wang, Shuang; Li, Hong-Wei; Yin, Zhen-Qiang; Chen, Wei; Yao, Yao; Huang, Jing-Zheng; Guo, Guang-Can; Han, Zheng-Fu

2014-01-01

We have demonstrated a proof-of-principle experiment of reference-frame-independent phase coding quantum key distribution (RFI-QKD) over an 80-km optical fiber. After considering the finite-key bound, we still achieve a distance of 50 km. In this scenario, the phases of the basis states are related by a slowly time-varying transformation. Furthermore, we developed and realized a new decoy state method for RFI-QKD systems with weak coherent sources to counteract the photon-number-splitting attack. With the help of a reference-frame-independent protocol and a Michelson interferometer with Faraday rotator mirrors, our system is rendered immune to the slow phase changes of the interferometer and the polarization disturbances of the channel, making the procedure very robust. PMID:24402550

Whisking mechanics and active sensing

PubMed Central

Bush, Nicholas E; Solla, Sara A

2017-01-01

We describe recent advances in quantifying the three-dimensional (3D) geometry and mechanics of whisking. Careful delineation of relevant 3D reference frames reveals important geometric and mechanical distinctions between the localization problem (‘where’ is an object) and the feature extraction problem (‘what’ is an object). Head-centered and resting-whisker reference frames lend themselves to quantifying temporal and kinematic cues used for object localization. The whisking-centered reference frame lends itself to quantifying the contact mechanics likely associated with feature extraction. We offer the ‘windowed sampling’ hypothesis for active sensing: that rats can estimate an object’s spatial features by integrating mechanical information across whiskers during brief (25–60 ms) windows of ‘haptic enclosure’ with the whiskers, a motion that resembles a hand grasp. PMID:27632212

Whisking mechanics and active sensing.

PubMed

Bush, Nicholas E; Solla, Sara A; Hartmann, Mitra Jz

2016-10-01

We describe recent advances in quantifying the three-dimensional (3D) geometry and mechanics of whisking. Careful delineation of relevant 3D reference frames reveals important geometric and mechanical distinctions between the localization problem ('where' is an object) and the feature extraction problem ('what' is an object). Head-centered and resting-whisker reference frames lend themselves to quantifying temporal and kinematic cues used for object localization. The whisking-centered reference frame lends itself to quantifying the contact mechanics likely associated with feature extraction. We offer the 'windowed sampling' hypothesis for active sensing: that rats can estimate an object's spatial features by integrating mechanical information across whiskers during brief (25-60ms) windows of 'haptic enclosure' with the whiskers, a motion that resembles a hand grasp. Copyright © 2016. Published by Elsevier Ltd.

Record-Breaking Radio Astronomy Project to Measure Sky with Extreme Precision

NASA Astrophysics Data System (ADS)

2009-11-01

Astronomers will tie together the largest collection of the world's radio telescopes ever assembled to work as a single observing tool in a project aimed at improving the precision of the reference frame scientists use to measure positions in the sky. The National Science Foundation's Very Long Baseline Array (VLBA) will be a key part of the project, which is coordinated by the International VLBI Service for Geodesy and Astrometry. For 24 hours, starting Wednesday, November 18, and ending Thursday, November 19, 35 radio telescopes located on seven continents will observe 243 distant quasars. The quasars, galaxies with supermassive black holes at their cores, are profuse emitters of radio waves, and also are so distant that, despite their actual motions in space, they appear stationary as seen from Earth. This lack of apparent motion makes them ideal celestial landmarks for anchoring a grid system, similar to earthly latitude and longitude, used to mark the positions of celestial objects. Data from all the radio telescopes will be combined to make them work together as a system capable of measuring celestial positions with extremely high precision. The technique used, called very long baseline interferometry (VLBI), has been used for decades for both astronomical and geodetic research. However, no previous position-measuring observation has used as many radio telescopes or observed as many objects in a single session. The previous record was a 23-telescope observation. At a meeting in Brazil last August, the International Astronomical Union adopted a new reference frame for celestial positions that will be used starting on January 1. This new reference frame uses a set of 295 quasars to define positions, much like surveyor's benchmarks in a surburban subdivision. Because even with 35 radio telescopes around the world, there are some gaps in sky coverage, the upcoming observation will observe 243 of the 295. By observing so many quasars in a single observing session, problems of linking positions from one observing session to another can be avoided, the astronomers say. The result will be a much stronger, more precise, reference grid. Telescopes in Asia, Australia, Europe, North America, South America, Antarctica, and in the Pacific will participate. Improving the celestial positional grid will allow astronomers better to pinpoint the locations and measure the motions of objects in the sky. As astronomers increasingly study objects using multiple telescopes observing at different wavelengths, such as visible light, radio, infrared, etc., the improved positional grid will allow more accurate overlaying of the different images. The improved celestial reference frame also strengthens a terrestrial reference frame used for radio-telescope measurements that contribute to geophysical research. The precise geodetic measurements help geophysicists understand phenomena such as plate tectonics, earth tides, and processes that affect our planet's orientation in space. The VLBA is a continent-wide radio telescope system with 10, 240-ton dish antennas ranging from Hawaii to the Virgin Islands. Operated from the National Radio Astronomy Observatory's Pete V. Domenici Science Operations Center in Socorro, New Mexico, the VLBA offers the greatest resolving power, or ability to see fine detail, of any telescope in astronomy. The multi-telescope observation will be accompanied by public-outreach activities in celebration of the International Year of Astronomy. A public web page devoted to the observation will be hosted at Bordeaux Observatory, and some of the participating telescopes will have webcams available.

SIRGAS: the core geodetic infrastructure in Latin America and the Caribbean

NASA Astrophysics Data System (ADS)

Sanchez, L.; Brunini, C.; Drewes, H.; Mackern, V.; da Silva, A.

2013-05-01

Studying, understanding, and modelling geophysical phenomena, such as global change and geodynamics, require geodetic reference frames with (1) an order of accuracy higher than the magnitude of the effects we want to study, (2) consistency and reliability worldwide (the same accuracy everywhere), and (3) a long-term stability (the same order of accuracy at any time). The definition, realisation, maintenance, and wide-utilisation of the International Terrestrial Reference System (ITRS) are oriented to guarantee a globally unified geometric reference frame with reliability at the mm-level, i.e. the International Terrestrial Reference Frame (ITRF). The densification of the global ITRF in Latin America and The Caribbean is given by SIRGAS (Sistema de Referencia Geocéntrico para Las Américas), primary objective of which is to provide the most precise coordinates in the region. Therefore, SIRGAS is the backbone for all regional projects based on the generation, use, and analysis of geo-referenced data at national as well as at international level. Besides providing the reference for a wide range of scientific applications such as the monitoring of Earth's crust deformations, vertical movements, sea level variations, atmospheric studies, etc., SIRGAS is also the platform for practical applications such as engineering projects, digital administration of geographical data, geospatial data infrastructures, etc. According to this, the present contribution describes the main features of SIRGAS, giving special care to those challenges faced to continue providing the best possible, long-term stable and high-precise reference frame for Latin America and the Caribbean.

SIRGAS: ITRF densification in Latin America and the Caribbean

NASA Astrophysics Data System (ADS)

Brunini, C.; Costa, S.; Mackern, V.; Martínez, W.; Sánchez, L.; Seemüller, W.; da Silva, A.

2009-04-01

The continental reference frame of SIRGAS (Sistema de Referencia Geocéntrico para las Américas) is at present realized by the SIRGAS Continuously Operating Network (SIRGAS-CON) composed by about 200 stations distributed over all Latin America and the Caribbean. SIRGAS member countries are qualifying their national reference frames by installing continuously operating GNSS stations, which have to be consistently integrated into the continental network. As the number of these stations is rapidly increasing, the processing strategy of the SIRGAS-CON network was redefined during the SIRGAS 2008 General Meeting in May 2008. The new strategy relies upon the definition of two hierarchy levels: a) A core network (SIRGAS-CON-C) with homogeneous continental coverage and stabile site locations ensures the long-term stability of the reference frame and provides the primary link to the ITRS. Stations belonging to this network have been selected so that each country contributes with a number of stations defined according to its surface and guarantying that the selected stations are the best in operability, continuity, reliability, and geographical coverage. b) Several densification sub-networks (SIRGAS-CON-D) improve the accessibility to the reference frame. The SIRGAS-CON-D sub-networks shall correspond to the national reference frames, i.e., as an optimum there shall be as many sub-networks as countries in the region. The goal is that each country processes its own continuously stations following the SIRGAS processing guidelines, which are defined in accordance with the IERS and IGS standards and conventions. Since at present not all of the countries are operating a processing centre, the existing stations are classified in three densification networks (a Northern, a middle, and a Southern one), which are processed by three local processing centres until new ones are installed. As SIRGAS is defined as a densification of the ITRS, stations included in the core network, as well as in the densification sub-networks match the requirements, characteristics, and processing performance of the ITRF. The SIRGAS-CON-C network is processed by DGFI (Deutsches Geodätisches Forschungsinstitut, Germany) as the IGS-RNAAC-SIR. The Local Processing Centres are for the Northern sub-network IGAC (Instituto Geográfico Augustín Codazzi, Colombia), for the middle sub-network IBGE (Instituto Brasileiro de Geografia e Estátistica, Brazil), and for the Southern sub-network IGG-CIMA (Instituto de Geodesia y Geodinámica, Universidad Nacional de Cuyo, Argentina). These four Processing Centres deliver loosely constrained weekly solutions for station coordinates (i.e., satellite orbits, satellite clock offsets, and Earth orientation parameters are fixed to the final weekly IGS solutions and coordinates for all sites are constrained to 1 m). The individual contributions are integrated in a unified solution by the SIRGAS Combination Centres (DGFI and IBGE) according to the following strategy: 1) Individual solutions are reviewed/corrected for possible format problems, data inconsistencies, etc. 2) Constraints imposed in the delivered normal equations are removed. 3) Sub-networks are individually aligned to the IGS05 reference frame by applying the No Net Rotation (NNR) and No Net Translation (NNT) conditions. 4) Coordinates obtained in (3) for each sub-network are compared to IGS05 values and to each other in order to identify possible outliers. 5) Stations with large residuals (more than 10 mm in the N-E component, and more than 20 mm in the Up component) are reduced from the normal equations. Steps (3), (4), and (5) are done iteratively. 6) Since at present the four Analysis Centres are processing GPS observations only and all of them use the Bernese Software for computing weekly solutions, relative weighting factors are not applied in the combination. 7) Individual normal equations are accumulated and solved for computing a loosely constrained weekly solution for station coordinates (i.e., coordinates for all stations are constrained to 1 m). This solution in SINEX format is submitted to IGS for the global polyhedron. 8) Combination obtained in (7) is constrained by applying NNR+NNT conditions with respect to the IGS05 stations included the SIRGAS region to provide constrained coordinates for all SIRGAS-CON (core + densification) stations. The applied IGS05 reference coordinates correspond to the weekly IGS solution for the global network, i.e., coordinates included in the igsYYPwwww.snx files. This constrained solution provides the final weekly SIRGAS-CON coordinates for practical applications. The DGFI (i.e. IGS RNAAC SIR) weekly combinations are delivered to the IGS Data Centres for combination in the global polyhedron, and made available for users as official SIRGAS products, respectively. The IBGE weekly combinations provide control and back-up. The above described analysis strategy is applied since GPS week 1495. Before (since June 1996 to August 2008), the SIRGAS-CON network was totally processed by DGFI. Until now, results show a very good agreement with previous computations; however, the present sub-networks distribution has two main disadvantages: 1) Not all SIRGAS-CON stations are included in the same number of individual solutions, i.e., they are unequally weighted in the weekly combinations, and 2) since there are not enough Local Processing Centres, the required redundancy (each station processed by at least three processing centres) is not fulfilled. Therefore, efforts are being made to install additional Local Processing Centres in Latin American countries as Argentina, Ecuador, Mexico, Peru, Uruguay, and Venezuela.

Numerically constructed internal-coordinate Hamiltonian with Eckart embedding and its application for the inversion tunneling of ammonia.

PubMed

Fábri, Csaba; Mátyus, Edit; Császár, Attila G

2014-02-05

It is shown that the use of an Eckart-frame embedding with a kinetic energy operator expressed in curvilinear internal coordinates becomes feasible and straightforward to implement for arbitrary molecular compositions and internal coordinates if the operator is defined numerically over a (discrete variable representation) grid. The algorithm proposed utilizes the transformation method of Dymarsky and Kudin to maintain the rotational Eckart condition. In order to demonstrate the applicability and flexibility of our approach the non-rigid ammonia molecule is considered and the corresponding rotational-vibrational energy levels and wave functions are computed using kinetic energy operators with three different embeddings. Two of them fulfill the Eckart conditions corresponding to a trigonal pyramidal (C3v) and a trigonal planar (D3h) reference structure and the third one is a non-Eckart frame. The computed energy levels are, of course, identical, and the structure of the three different wave-function representations are analyzed in terms of the rigid rotor functions for a symmetric top. The possible advantages of one frame representation over another are discussed concerning the interpretation of the rovibrational states in terms of the traditional rigid rotor labels. Copyright © 2013 Elsevier B.V. All rights reserved.

An analysis of noun definition in Cantonese.

PubMed

To, Carol Kit Sum; Stokes, Stephanie; Man, Yonnie; T'sou, Benjamin

2013-03-01

This study investigated the noun definitions given by Cantonese speakers at different ages. Definitional responses on six concrete nouns from 1075 children aged 4;10 to 12;01 and 15 adults were analyzed with reference to the semantic content and the syntactic form. Results showed that conventional definitions produced by Cantonese adult speakers were realized with specific superordinates and more perceptual than functional attributes. The content was carried by a syntactic frame, "NP1, is NP2", where relative clause was not the predominant form of NP2 as in the English definition forms. Core attributes signifying the defining properties increased significantly with age while non-core attributes were observed relatively evenly throughout all groups. Preschoolers tended to drop the sentential-subject (i.e., NP1) and the copula is, and produce more functional than perceptual attributes. By Primary-2 (P2) (about 7;0), the taxonomic relation was coded with the frame of "NP1 is NP2". Beginning at P4 (about 9;0), children included a superordinate but the specificity of the adult-like superordinate was not achieved even by P6 (about 11;0). In general, developmental trends accorded with the trends observed in other languages, but typological features played a role in framing the development of the syntactic form.

Promotional Frames' Influence on Price Perceptions of Two Apparel Products.

ERIC Educational Resources Information Center

Stanforth, Nancy; Lennon, Sharron; Shin, Jung Im

2001-01-01

A study explored the differences in price perceptions of two apparel products when promotions were framed as either a price discount or a gift-with-purchase. The majority preferred the discount. Results illustrate the importance of promotional framing in forming consumer price perceptions. (Contains 30 references.) (Author/JOW)

The impact of cine EPID image acquisition frame rate on markerless soft-tissue tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yip, Stephen, E-mail: syip@lroc.harvard.edu; Rottmann, Joerg; Berbeco, Ross

2014-06-15

Purpose: Although reduction of the cine electronic portal imaging device (EPID) acquisition frame rate through multiple frame averaging may reduce hardware memory burden and decrease image noise, it can hinder the continuity of soft-tissue motion leading to poor autotracking results. The impact of motion blurring and image noise on the tracking performance was investigated. Methods: Phantom and patient images were acquired at a frame rate of 12.87 Hz with an amorphous silicon portal imager (AS1000, Varian Medical Systems, Palo Alto, CA). The maximum frame rate of 12.87 Hz is imposed by the EPID. Low frame rate images were obtained bymore » continuous frame averaging. A previously validated tracking algorithm was employed for autotracking. The difference between the programmed and autotracked positions of a Las Vegas phantom moving in the superior-inferior direction defined the tracking error (δ). Motion blurring was assessed by measuring the area change of the circle with the greatest depth. Additionally, lung tumors on 1747 frames acquired at 11 field angles from four radiotherapy patients are manually and automatically tracked with varying frame averaging. δ was defined by the position difference of the two tracking methods. Image noise was defined as the standard deviation of the background intensity. Motion blurring and image noise are correlated with δ using Pearson correlation coefficient (R). Results: For both phantom and patient studies, the autotracking errors increased at frame rates lower than 4.29 Hz. Above 4.29 Hz, changes in errors were negligible withδ < 1.60 mm. Motion blurring and image noise were observed to increase and decrease with frame averaging, respectively. Motion blurring and tracking errors were significantly correlated for the phantom (R = 0.94) and patient studies (R = 0.72). Moderate to poor correlation was found between image noise and tracking error with R −0.58 and −0.19 for both studies, respectively. Conclusions: Cine EPID image acquisition at the frame rate of at least 4.29 Hz is recommended. Motion blurring in the images with frame rates below 4.29 Hz can significantly reduce the accuracy of autotracking.« less

Reward- and attention-related biasing of sensory selection in visual cortex.

PubMed

Buschschulte, Antje; Boehler, Carsten N; Strumpf, Hendrik; Stoppel, Christian; Heinze, Hans-Jochen; Schoenfeld, Mircea A; Hopf, Jens-Max

2014-05-01

Attention to task-relevant features leads to a biasing of sensory selection in extrastriate cortex. Features signaling reward seem to produce a similar bias, but how modulatory effects due to reward and attention relate to each other is largely unexplored. To address this issue, it is critical to separate top-down settings defining reward relevance from those defining attention. To this end, we used a visual search paradigm in which the target's definition (attention to color) was dissociated from reward relevance by delivering monetary reward on search frames where a certain task-irrelevant color was combined with the target-defining color to form the target object. We assessed the state of neural biasing for the attended and reward-relevant color by analyzing the neuromagnetic brain response to asynchronously presented irrelevant distractor probes drawn in the target-defining color, the reward-relevant color, and a completely irrelevant color as a reference. We observed that for the prospect of moderate rewards, the target-defining color but not the reward-relevant color produced a selective enhancement of the neuromagnetic response between 180 and 280 msec in ventral extrastriate visual cortex. Increasing reward prospect caused a delayed attenuation (220-250 msec) of the response to reward probes, which followed a prior (160-180 msec) response enhancement in dorsal ACC. Notably, shorter latency responses in dorsal ACC were associated with stronger attenuation in extrastriate visual cortex. Finally, an analysis of the brain response to the search frames revealed that the presence of the reward-relevant color in search distractors elicited an enhanced response that was abolished after increasing reward size. The present data together indicate that when top-down definitions of reward relevance and attention are separated, the behavioral significance of reward-associated features is still rapidly coded in higher-level cortex areas, thereby commanding effective top-down inhibitory control to counter a selection bias for those features in extrastriate visual cortex.

Frame of Reference Model of Self-Concept and Locus of Control: A Cross Gender Study in the United Arab Emirates.

ERIC Educational Resources Information Center

Abu-Hilal, Maher M.

A study tested predictions for I/E (internal external) frame of reference model and extended this model to include locus of control. A sample of upper elementary (n=181) and junior high (n=191) students in the United Arab Emirates participated in the study. Structural equation modeling (SEM) analyses provided support to the external comparison…

The Internal/External Frame of Reference Model of Self-Concept and Achievement Relations: Age-Cohort and Cross-Cultural Differences

ERIC Educational Resources Information Center

Marsh, Herbert W.; Abduljabbar, Adel Salah; Parker, Philip D.; Morin, Alexandre J. S.; Abdelfattah, Faisal; Nagengast, Benjamin; Möller, Jens; Abu-Hilal, Maher M.

2015-01-01

The internal/external frame of reference (I/E) model and dimensional comparison theory posit paradoxical relations between achievement (ACH) and self-concept (SC) in mathematics (M) and verbal (V) domains; ACH in each domain positively affects SC in the matching domain (e.g., MACH to MSC) but negatively in the nonmatching domain (e.g., MACH to…

Verbal and Math Self-Concepts: An Extension of the Internal/External Frame of Reference Model.

ERIC Educational Resources Information Center

Marsh, Herbert W.; Byrne, Barbara M.

The internal/external (I/E) frame of reference model describes relations among Verbal self-concept (VSC), Math self-concept (MSC), and corresponding achievement scores (VACH, MACH). In support of the model Marsh (1986) found that: (1) VSC and MSC were nearly uncorrelated; (2) the effect of VACH on VSC, and of MACH on MSC, were positive; but (3)…

The Effect of Motion Analysis Activities in a Video-Based Laboratory in Students' Understanding of Position, Velocity and Frames of Reference

ERIC Educational Resources Information Center

Koleza, Eugenia; Pappas, John

2008-01-01

In this article, we present the results of a qualitative research project on the effect of motion analysis activities in a Video-Based Laboratory (VBL) on students' understanding of position, velocity and frames of reference. The participants in our research were 48 pre-service teachers enrolled in Education Departments with no previous strong…

Frame-of-Reference Training Effectiveness: Effects of Goal Orientation and Self-Efficacy on Affective, Cognitive, Skill-Based, and Transfer Outcomes

ERIC Educational Resources Information Center

Dierdorff, Erich C.; Surface, Eric A.; Brown, Kenneth G.

2010-01-01

Empirical evidence supporting frame-of-reference (FOR) training as an effective intervention for calibrating raters is convincing. Yet very little is known about who does better or worse in FOR training. We conducted a field study of how motivational factors influence affective, cognitive, and behavioral learning outcomes, as well as near transfer…

The special theory of Brownian relativity: equivalence principle for dynamic and static random paths and uncertainty relation for diffusion.

PubMed

Mezzasalma, Stefano A

2007-03-15

The theoretical basis of a recent theory of Brownian relativity for polymer solutions is deepened and reexamined. After the problem of relative diffusion in polymer solutions is addressed, its two postulates are formulated in all generality. The former builds a statistical equivalence between (uncorrelated) timelike and shapelike reference frames, that is, among dynamical trajectories of liquid molecules and static configurations of polymer chains. The latter defines the "diffusive horizon" as the invariant quantity to work with in the special version of the theory. Particularly, the concept of universality in polymer physics corresponds in Brownian relativity to that of covariance in the Einstein formulation. Here, a "universal" law consists of a privileged observation, performed from the laboratory rest frame and agreeing with any diffusive reference system. From the joint lack of covariance and simultaneity implied by the Brownian Lorentz-Poincaré transforms, a relative uncertainty arises, in a certain analogy with quantum mechanics. It is driven by the difference between local diffusion coefficients in the liquid solution. The same transformation class can be used to infer Fick's second law of diffusion, playing here the role of a gauge invariance preserving covariance of the spacetime increments. An overall, noteworthy conclusion emerging from this view concerns the statistics of (i) static macromolecular configurations and (ii) the motion of liquid molecules, which would be much more related than expected.

Frequency-domain preprocessing and directional correlation-based feature extraction for classification of the buried objects using GPR B-scan data

NASA Astrophysics Data System (ADS)

Bahadirlar, Yildirim; Kaplan, Gulay B.

2004-09-01

A new preprocessing and feature extracting approach for classification of non-metallic buried objects are aimed using GPR B-scan data. A frequency-domain adaptive filter without a reference channel effectively removes the background signal resulting mostly from the discontinuity on the air-to-ground path of the electromagnetic waves. The filter only needs average of the first five A-scans as the reference signal for this elimination, and also serves for masking of the B-scan in the frequency-domain. A preprocessed GPR data with significantly suppressed clutter is then obtained by precisely positioning the Hanning window in the frequency-domain. A directional correlation function defined over a B-scan frame gives distinctive curves of buried objects. The main axis of directional correlation, on which the pivotal correlating pixels and short lines of pixels being correlated are considered, makes an angle to the scanning direction of the B-scan. This form of correlation is applied to the frame from the left-hand and the right-hand side and two over-plotted curves are obtained. Nine measures as features emphasizing directional signatures are extracted from these curves. Nine-element feature vectors are applied to the two-layer Artificial Neural Network and preliminary results over test set are promising to continue to comprehensive training and testing processes.

Deep mantle structure as a reference frame for movements in and on the Earth

PubMed Central

Torsvik, Trond H.; van der Voo, Rob; Doubrovine, Pavel V.; Burke, Kevin; Steinberger, Bernhard; Ashwal, Lewis D.; Trønnes, Reidar G.; Webb, Susan J.; Bull, Abigail L.

2014-01-01

Earth’s residual geoid is dominated by a degree-2 mode, with elevated regions above large low shear-wave velocity provinces on the core–mantle boundary beneath Africa and the Pacific. The edges of these deep mantle bodies, when projected radially to the Earth’s surface, correlate with the reconstructed positions of large igneous provinces and kimberlites since Pangea formed about 320 million years ago. Using this surface-to-core–mantle boundary correlation to locate continents in longitude and a novel iterative approach for defining a paleomagnetic reference frame corrected for true polar wander, we have developed a model for absolute plate motion back to earliest Paleozoic time (540 Ma). For the Paleozoic, we have identified six phases of slow, oscillatory true polar wander during which the Earth’s axis of minimum moment of inertia was similar to that of Mesozoic times. The rates of Paleozoic true polar wander (<1°/My) are compatible with those in the Mesozoic, but absolute plate velocities are, on average, twice as high. Our reconstructions generate geologically plausible scenarios, with large igneous provinces and kimberlites sourced from the margins of the large low shear-wave velocity provinces, as in Mesozoic and Cenozoic times. This absolute kinematic model suggests that a degree-2 convection mode within the Earth’s mantle may have operated throughout the entire Phanerozoic. PMID:24889632

Deep mantle structure as a reference frame for movements in and on the Earth.

PubMed

Torsvik, Trond H; van der Voo, Rob; Doubrovine, Pavel V; Burke, Kevin; Steinberger, Bernhard; Ashwal, Lewis D; Trønnes, Reidar G; Webb, Susan J; Bull, Abigail L

2014-06-17

Earth's residual geoid is dominated by a degree-2 mode, with elevated regions above large low shear-wave velocity provinces on the core-mantle boundary beneath Africa and the Pacific. The edges of these deep mantle bodies, when projected radially to the Earth's surface, correlate with the reconstructed positions of large igneous provinces and kimberlites since Pangea formed about 320 million years ago. Using this surface-to-core-mantle boundary correlation to locate continents in longitude and a novel iterative approach for defining a paleomagnetic reference frame corrected for true polar wander, we have developed a model for absolute plate motion back to earliest Paleozoic time (540 Ma). For the Paleozoic, we have identified six phases of slow, oscillatory true polar wander during which the Earth's axis of minimum moment of inertia was similar to that of Mesozoic times. The rates of Paleozoic true polar wander (<1°/My) are compatible with those in the Mesozoic, but absolute plate velocities are, on average, twice as high. Our reconstructions generate geologically plausible scenarios, with large igneous provinces and kimberlites sourced from the margins of the large low shear-wave velocity provinces, as in Mesozoic and Cenozoic times. This absolute kinematic model suggests that a degree-2 convection mode within the Earth's mantle may have operated throughout the entire Phanerozoic.

Theory and Realization of Global Terrestrial Reference Systems

NASA Technical Reports Server (NTRS)

Ma, C.; Bolotin, S.; Gipson, J.; Gordon, D.; Le Bail, K.; MacMillan, D.

2010-01-01

Comparison of realizations of the terrestrial reference frame. IGN and DGFI both generated realizations of the terrestrial reference frame under the auspices of the IERS from combination of the same space geodetic data. We examined both results for VLBI sites using the full geodetic VLBI data set with respect to site positions and velocities and time series of station positions, baselines and Earth orientation parameters. One of the difficulties encountered was matching episodic breaks and periods of non-linear motion of the two realizations with the VLBI models. Our analysis and conclusions will be discussed.

The African Reference Frame (AFREF) project: a fundamental geodetic tool for Africa

NASA Astrophysics Data System (ADS)

Farah, H.

2009-04-01

AFREF has as objective the establishment and maintenance of a unified geodetic reference frame for Africa, which will support and facilitate fundamental scientific and technical projects. The installation of observation systems all over Africa will provide important data that can be used in many different scientific fields (e.g., geodynamics, meteorological). Furthermore, AFREF will create an uniform frame that will support development projects, uniform environmental and mapping programmes as well as aid in resolving current and future international boundary disputes. This reference frame will be based on the International Terrestrial Reference Frame (ITRF) and will be realised through the establishment of a network of permanent Global Navigation Satellite System (GNSS) receivers. In close collaboration with several institutional role players, AFREF is an initiative of the United Nations Economic Commission for Africa (UNECA) Committee on Development Information (CODI). A steering committee is currently responsible for the over-all management and coordination of the implementation of AFREF. Implementation of AFREF is envisaged to be at national level in collaboration with National Mapping Organizations. Furthermore, many scientific Institutions are contributing for the densification of the network. The current status of the AFREF network will be discussed in detail. Several CORS systems have been installed to support AFREF specifically. In addition, most or all of the IGS stations located in Africa will automatically qualify as AFREF core stations. Furthermore, we will show examples of interaction between specific projects and AFREF that are contributing for the development of science in Africa.

Frames of reference in spatial language acquisition.

PubMed

Shusterman, Anna; Li, Peggy

2016-08-01

Languages differ in how they encode spatial frames of reference. It is unknown how children acquire the particular frame-of-reference terms in their language (e.g., left/right, north/south). The present paper uses a word-learning paradigm to investigate 4-year-old English-speaking children's acquisition of such terms. In Part I, with five experiments, we contrasted children's acquisition of novel word pairs meaning left-right and north-south to examine their initial hypotheses and the relative ease of learning the meanings of these terms. Children interpreted ambiguous spatial terms as having environment-based meanings akin to north and south, and they readily learned and generalized north-south meanings. These studies provide the first direct evidence that children invoke geocentric representations in spatial language acquisition. However, the studies leave unanswered how children ultimately acquire "left" and "right." In Part II, with three more experiments, we investigated why children struggle to master body-based frame-of-reference words. Children successfully learned "left" and "right" when the novel words were systematically introduced on their own bodies and extended these words to novel (intrinsic and relative) uses; however, they had difficulty learning to talk about the left and right sides of a doll. This difficulty was paralleled in identifying the left and right sides of the doll in a non-linguistic memory task. In contrast, children had no difficulties learning to label the front and back sides of a doll. These studies begin to paint a detailed account of the acquisition of spatial terms in English, and provide insights into the origins of diverse spatial reference frames in the world's languages. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Impact of quasar proper motions on the alignment between the International Celestial Reference Frame and the Gaia reference frame

NASA Astrophysics Data System (ADS)

Liu, J.-C.; Malkin, Z.; Zhu, Z.

2018-03-01

The International Celestial Reference Frame (ICRF) is currently realized by the very long baseline interferometry (VLBI) observations of extragalactic sources with the zero proper motion assumption, while Gaia will observe proper motions of these distant and faint objects to an accuracy of tens of microarcseconds per year. This paper investigates the difference between VLBI and Gaia quasar proper motions and it aims to understand the impact of quasar proper motions on the alignment of the ICRF and Gaia reference frame. We use the latest time series data of source coordinates from the International VLBI Service analysis centres operated at Goddard Space Flight Center (GSF2017) and Paris observatory (OPA2017), as well as the Gaia auxiliary quasar solution containing 2191 high-probability optical counterparts of the ICRF2 sources. The linear proper motions in right ascension and declination of VLBI sources are derived by least-squares fits while the proper motions for Gaia sources are simulated taking into account the acceleration of the Solar system barycentre and realistic uncertainties depending on the source brightness. The individual and global features of source proper motions in GSF2017 and OPA2017 VLBI data are found to be inconsistent, which may result from differences in VLBI observations, data reduction and analysis. A comparison of the VLBI and Gaia proper motions shows that the accuracies of the components of rotation and glide between the two systems are 2-4 μas yr- 1 based on about 600 common sources. For the future alignment of the ICRF and Gaia reference frames at different wavelengths, the proper motions of quasars must necessarily be considered.

A computational model for reference-frame synthesis with applications to motion perception.

PubMed

Clarke, Aaron M; Öğmen, Haluk; Herzog, Michael H

2016-09-01

As discovered by the Gestaltists, in particular by Duncker, we often perceive motion to be within a non-retinotopic reference frame. For example, the motion of a reflector on a bicycle appears to be circular, whereas, it traces out a cycloidal path with respect to external world coordinates. The reflector motion appears to be circular because the human brain subtracts the horizontal motion of the bicycle from the reflector motion. The bicycle serves as a reference frame for the reflector motion. Here, we present a general mathematical framework, based on vector fields, to explain non-retinotopic motion processing. Using four types of non-retinotopic motion paradigms, we show how the theory works in detail. For example, we show how non-retinotopic motion in the Ternus-Pikler display can be computed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Orbital motions of astronomical bodies and their centre of mass from different reference frames: a conceptual step between the geocentric and heliocentric models

NASA Astrophysics Data System (ADS)

Guerra, André G. C.; Simeão Carvalho, Paulo

2016-09-01

The motion of astronomical bodies and the centre of mass of the system is not always well perceived by students. One of the struggles is the conceptual change of reference frame, which is the same that held back the acceptance of the Heliocentric model over the Geocentric one. To address the question, the notion of centre of mass, motion equations (and their numerical solution for a system of multiple bodies), and change of frame of reference is introduced. The discussion is done based on conceptual and real world examples, using the solar system. Consequently, through the use of simple ‘do it yourself’ methods and basic equations, students can debate complex motions, and have a wider and potentially effective understanding of physics.

Effects of visual information regarding allocentric processing in haptic parallelity matching.

PubMed

Van Mier, Hanneke I

2013-10-01

Research has revealed that haptic perception of parallelity deviates from physical reality. Large and systematic deviations have been found in haptic parallelity matching most likely due to the influence of the hand-centered egocentric reference frame. Providing information that increases the influence of allocentric processing has been shown to improve performance on haptic matching. In this study allocentric processing was stimulated by providing informative vision in haptic matching tasks that were performed using hand- and arm-centered reference frames. Twenty blindfolded participants (ten men, ten women) explored the orientation of a reference bar with the non-dominant hand and subsequently matched (task HP) or mirrored (task HM) its orientation on a test bar with the dominant hand. Visual information was provided by means of informative vision with participants having full view of the test bar, while the reference bar was blocked from their view (task VHP). To decrease the egocentric bias of the hands, participants also performed a visual haptic parallelity drawing task (task VHPD) using an arm-centered reference frame, by drawing the orientation of the reference bar. In all tasks, the distance between and orientation of the bars were manipulated. A significant effect of task was found; performance improved from task HP, to VHP to VHPD, and HM. Significant effects of distance were found in the first three tasks, whereas orientation and gender effects were only significant in tasks HP and VHP. The results showed that stimulating allocentric processing by means of informative vision and reducing the egocentric bias by using an arm-centered reference frame led to most accurate performance on parallelity matching. © 2013 Elsevier B.V. All rights reserved.

Solar energy system with wind vane

DOEpatents

Grip, Robert E

2015-11-03

A solar energy system including a pedestal defining a longitudinal axis, a frame that is supported by the pedestal and that is rotateable relative to the pedestal about the longitudinal axis, the frame including at least one solar device, and a wind vane operatively connected to the frame to urge the frame relative to the pedestal about the longitudinal axis in response to wind acting on the wind vane.

SU-E-J-112: The Impact of Cine EPID Image Acquisition Frame Rate On Markerless Soft-Tissue Tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yip, S; Rottmann, J; Berbeco, R

2014-06-01

Purpose: Although reduction of the cine EPID acquisition frame rate through multiple frame averaging may reduce hardware memory burden and decrease image noise, it can hinder the continuity of soft-tissue motion leading to poor auto-tracking results. The impact of motion blurring and image noise on the tracking performance was investigated. Methods: Phantom and patient images were acquired at a frame rate of 12.87Hz on an AS1000 portal imager. Low frame rate images were obtained by continuous frame averaging. A previously validated tracking algorithm was employed for auto-tracking. The difference between the programmed and auto-tracked positions of a Las Vegas phantommore » moving in the superior-inferior direction defined the tracking error (δ). Motion blurring was assessed by measuring the area change of the circle with the greatest depth. Additionally, lung tumors on 1747 frames acquired at eleven field angles from four radiotherapy patients are manually and automatically tracked with varying frame averaging. δ was defined by the position difference of the two tracking methods. Image noise was defined as the standard deviation of the background intensity. Motion blurring and image noise were correlated with δ using Pearson correlation coefficient (R). Results: For both phantom and patient studies, the auto-tracking errors increased at frame rates lower than 4.29Hz. Above 4.29Hz, changes in errors were negligible with δ<1.60mm. Motion blurring and image noise were observed to increase and decrease with frame averaging, respectively. Motion blurring and tracking errors were significantly correlated for the phantom (R=0.94) and patient studies (R=0.72). Moderate to poor correlation was found between image noise and tracking error with R -0.58 and -0.19 for both studies, respectively. Conclusion: An image acquisition frame rate of at least 4.29Hz is recommended for cine EPID tracking. Motion blurring in images with frame rates below 4.39Hz can substantially reduce the accuracy of auto-tracking. This work is supported in part by the Varian Medical Systems, Inc.« less

78 FR 46528 - Surety Bond Guarantee Program

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-01

... proposing to reduce the time frame allowed for a Surety to reimburse or credit SBA for salvage and recovery... the time frame reference required by the Recovery Act, which has expired, and by inserting the...)(1). SBA is proposing to reduce the time frame allowed for a Prior Approval Surety to submit a claim...

STARS[R] Spring 2012 Quarterly Review: Framing Campus Sustainability

ERIC Educational Resources Information Center

Urbanski, Monika

2012-01-01

The Spring 2012 SQR: "Framing Campus Sustainability," features stories that frame the evolving concept of sustainability in higher education. Included in this issue are a snapshot of ratings-to-date, a focus on credits within the Operations (OP) category, and insights into how institutions are defining and interpreting the evolving…

Calculation of parameters of combined frame and roof bolting

NASA Astrophysics Data System (ADS)

Ivanov, S. I.; Titov, N. V.; Privalov, A. A.; Trunov, I. T.; Sarychev, V. I.

2017-10-01

The paper presents the method of calculation of the combined frame and roof bolting. Recommendations on providing joint operation of roof bolting with steel support frames are given. Graphs for determining standard rock movement, as well as for defining proof load on the yielding support, were developed.

Some aspects of an induced electric dipole moment in rotating and non-rotating frames.

PubMed

Oliveira, Abinael B; Bakke, Knut

2017-06-01

Quantum effects on a neutral particle (atom or molecule) with an induced electric dipole moment are investigated when it is subject to the Kratzer potential and a scalar potential proportional to the radial distance. In addition, this neutral is placed in a region with electric and magnetic fields. This system is analysed in both non-rotating and rotating reference frames. Then, it is shown that bound state solutions to the Schrödinger equation can be achieved and, in the search for polynomial solutions to the radial wave function, a restriction on the values of the cyclotron frequency is analysed in both reference frames.

The Internal/External Frame of Reference of Academic Self-Concept: Extension to a Foreign Language and the Role of Language of Instruction

ERIC Educational Resources Information Center

Xu, Man K.; Marsh, Herbert W.; Hau, Kit-Tai; Ho, Irene T.; Morin, Alexandre J. S.; Abduljabbar, Adel S.

2013-01-01

The internal/external frame of reference (I/E) model (Marsh, 1986) posits that the effects of contrasting math and verbal domains of achievement are positive for matching academic self-concepts (ASCs) but negative for nonmatching ASCs (i.e., math achievement on verbal ASC; verbal achievement on math ASC). We extend the classic I/E model by…

The Longitudinal Interplay of Students' Academic Self-Concepts and Achievements within and across Domains: Replicating and Extending the Reciprocal Internal/External Frame of Reference Model

ERIC Educational Resources Information Center

Niepel, Christoph; Brunner, Martin; Preckel, Franzis

2014-01-01

Students' cognitive and motivational profiles have a large impact on their academic careers. The development of such profiles can partly be explained by the reciprocal internal/external frame of reference model (RI/E model). The RI/E model predicts positive and negative longitudinal effects between academic self-concepts and achievements within…

An Analysis of the Accessibility of Earth-Approaching Asteroids.

DTIC Science & Technology

1985-12-01

coordinate system. Outputs are the X,Y,Z coordinates of the sun in the geocentric-equatorial coordinate system. The obliquity of the ecliptic is a variable...All positions and velocities are calculated in heliocentric- ecliptic coordinates thus requiring no transformations into unusual frames of reference...tion vectors of the departure and arrival planets in the heliocentric- ecliptic reference frame. ,\\. , V I(W() - / n (16) %: ~22% .b The angle between

Explaining as Mediated Action: An Analysis of Pre-Service Teachers' Account of Forces of Inertia in Non-Inertial Frames of Reference

ERIC Educational Resources Information Center

de Pereira, Alexsandro Pereira; Lima Junior, Paulo; Rodrigues, Renato Felix

2016-01-01

Explaining is one of the most important everyday practices in science education. In this article, we examine how scientific explanations could serve as cultural tools for members of a group of pre-service physics teachers. Specifically, we aim at their use of explanations about forces of inertia in non-inertial frames of reference. A basic…

The principle of relativity, superluminality and EPR experiments. "Riserratevi sotto coverta ..."

NASA Astrophysics Data System (ADS)

Cocciaro, B.

2015-07-01

The principle of relativity claims the invariance of the results for experiments carried out in inertial reference frames if the system under examination is not in interaction with the outside world. In this paper it is analysed a model suggested by J. S. Bell, and later developed by P. H. Eberhard, D. Bohm and B. Hiley on the basis of which the EPR correlations would be due to superluminal exchanges between the various parts of the entangled system under examination. In the model the existence of a privileged reference frame (PF) for the propagation of superluminal signals is hypothesized so that these superluminal signals may not give rise to causal paradoxes. According to this model, in an EPR experiment, the entangled system interacts with the outer world since the result of the experiment depends on an entity (the reference frame PF) that is not prepared by the experimenter. The existence of this privileged reference frame makes the model non invariant for Lorentz transformations. In this paper, in opposition to what claimed by the authors mentioned above, the perfect compatibility of the model with the theory of relativity is strongly maintained since, as already said, the principle of relativity does not require that the results of experiments carried out on systems interacting with the outside world should be invariant.

Reduction of photographic observations of asteroids to the reference frame of a single catalog

NASA Astrophysics Data System (ADS)

Chernetenko, Yu. A.

2008-04-01

In 2000, the last international program of photographic observations of selected asteroids aimed at the determination of the mutual orientation of the dynamic and stellar coordinate systems came to an end. The Institute of Applied Astronomy of the Russian Academy of Sciences collected more than 25 000 observations for 15 asteroids spanning from 1949 through 1995. These observations were reduced to the reference frame of the Hipparcos catalog using dependencies published along with observations. The accuracy of observations of selected asteroids was 0.30 arcsec, which is comparable to that of modern CCD observations of minor planets. The observations are available at ftp://quasar.ipa.nw.ru/pub/SMP . An important advantage of these observations is that they are already reduced to the reference frame of a single catalog. Our criteria for the quality of the reduction methods and the accuracy of the observations are based on estimating the parameters of the orientation of the reference frames of the PPM and Hipparcos catalogs with respect to DE200/LE200. The most reliable results are those obtained when reducing old optical observations along with modern ground-based and space-borne observations.

Effects of non-tidal atmospheric loading on a Kalman filter-based terrestrial reference frame

NASA Astrophysics Data System (ADS)

Abbondanza, C.; Altamimi, Z.; Chin, T. M.; Collilieux, X.; Dach, R.; Heflin, M. B.; Gross, R. S.; König, R.; Lemoine, F. G.; MacMillan, D. S.; Parker, J. W.; van Dam, T. M.; Wu, X.

2013-12-01

The International Terrestrial Reference Frame (ITRF) adopts a piece-wise linear model to parameterize regularized station positions and velocities. The space-geodetic (SG) solutions from VLBI, SLR, GPS and DORIS global networks used as input in the ITRF combination process account for tidal loading deformations, but ignore the non-tidal part. As a result, the non-linear signal observed in the time series of SG-derived station positions in part reflects non-tidal loading displacements not introduced in the SG data reduction. In this analysis, the effect of non-tidal atmospheric loading (NTAL) corrections on the TRF is assessed adopting a Remove/Restore approach: (i) Focusing on the a-posteriori approach, the NTAL model derived from the National Center for Environmental Prediction (NCEP) surface pressure is removed from the SINEX files of the SG solutions used as inputs to the TRF determinations. (ii) Adopting a Kalman-filter based approach, a linear TRF is estimated combining the 4 SG solutions free from NTAL displacements. (iii) Linear fits to the NTAL displacements removed at step (i) are restored to the linear reference frame estimated at (ii). The velocity fields of the (standard) linear reference frame in which the NTAL model has not been removed and the one in which the model has been removed/restored are compared and discussed.

Learning to Explain Astronomy Across Moving Frames of Reference: Exploring the role of classroom and planetarium-based instructional contexts

NASA Astrophysics Data System (ADS)

Plummer, Julia Diane; Kocareli, Alicia; Slagle, Cynthia

2014-05-01

Learning astronomy involves significant spatial reasoning, such as learning to describe Earth-based phenomena and understanding space-based explanations for those phenomena as well as using the relevant size and scale information to interpret these frames of reference. This study examines daily celestial motion (DCM) as one case of how children learn to move between frames of reference in astronomy wherein one explains Earth-based descriptions of the Sun's, Moon's, and stars' apparent motion using the Earth's daily rotation. We analysed interviews with 8-9-year-old students (N = 99) who participated in one of four instructional conditions emphasizing: the space-based perspective; the Earth-based perspective in the planetarium; constructing explanations for the Earth-based observations; and a combination of the planetarium plus constructing explanations in the classroom. We used an embodied cognition framework to analyse outcomes while also considering challenges learners face due to the high cognitive demands of spatial reasoning. Results support the hypothesis that instruction should engage students in learning both the Earth-based observations and space-based explanations, as focusing on a single frame of reference resulted in less sophisticated explanations; however, few students were able to construct a fully scientific explanation after instruction.

Cognitive Phenotypes and the Evolution of Animal Decisions.

PubMed

Mendelson, Tamra C; Fitzpatrick, Courtney L; Hauber, Mark E; Pence, Charles H; Rodríguez, Rafael L; Safran, Rebecca J; Stern, Caitlin A; Stevens, Jeffrey R

2016-11-01

Despite the clear fitness consequences of animal decisions, the science of animal decision making in evolutionary biology is underdeveloped compared with decision science in human psychology. Specifically, the field lacks a conceptual framework that defines and describes the relevant components of a decision, leading to imprecise language and concepts. The 'judgment and decision-making' (JDM) framework in human psychology is a powerful tool for framing and understanding human decisions, and we apply it here to components of animal decisions, which we refer to as 'cognitive phenotypes'. We distinguish multiple cognitive phenotypes in the context of a JDM framework and highlight empirical approaches to characterize them as evolvable traits. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel Software for Performing Leksell Stereotactic Surgery without the Use of Printing Films: Technical Note.

PubMed

Hashizume, Akira; Akimitsu, Tomohide; Iida, Koji; Kagawa, Kota; Katagiri, Masaya; Hanaya, Ryosuke; Arita, Kazunori; Kurisu, Kaoru

2016-01-01

Hospitals in Japan have recently begun to employ the DICOM viewer system on desktop or laptop monitors. However, conventional embedding surgery for deep-brain stimulation with the Leksell stereotactic system (LSS) requires printed X-ray films for defining the coordination, coregistration of actual surgical films with the reference coordinates, and validation of the needle trajectories. While just performing these procedures on desktop or laptop monitors, the authors were able to develop novel software to facilitate complete digital manipulation with the Leksell frame without printing films. In this study, we validated the practical use of LSS, and benefit of this software in the Takanobashi Central Hospital and Kagoshima University Hospital.

Automated extraction of knowledge for model-based diagnostics

NASA Technical Reports Server (NTRS)

Gonzalez, Avelino J.; Myler, Harley R.; Towhidnejad, Massood; Mckenzie, Frederic D.; Kladke, Robin R.

1990-01-01

The concept of accessing computer aided design (CAD) design databases and extracting a process model automatically is investigated as a possible source for the generation of knowledge bases for model-based reasoning systems. The resulting system, referred to as automated knowledge generation (AKG), uses an object-oriented programming structure and constraint techniques as well as internal database of component descriptions to generate a frame-based structure that describes the model. The procedure has been designed to be general enough to be easily coupled to CAD systems that feature a database capable of providing label and connectivity data from the drawn system. The AKG system is capable of defining knowledge bases in formats required by various model-based reasoning tools.

Vombat: an open source proof-of-concept for the use of Digital outcrop models as reference frame for stratigraphic observations

NASA Astrophysics Data System (ADS)

Penasa, Luca; Franceschi, Marco; Preto, Nereo; Girardeau-Montaut, Daniel

2015-04-01

Three-dimensional Virtual Outcrop Models (VOMs), often produced using terrestrial laser scanning or photogrammetry, have become popular in the Geosciences. The main feature of a VOM is that it allows for a quantification of the 3D geometry and/or distribution of geologic features that range from rock properties to structural elements. This actually generated much of the interest in VOMs by the oil and gas industry. The potential importance of a VOM in stratigraphy, however, does not seems completely disclosed yet. Indeed outcrops are the primary sources of data for a number of stratigraphic studies (e.g. palaeontology, sedimentology, cyclostratigraphy, geochemistry...). All the observations are typically reported on stratigraphic logs which constitute an idealized representation of the stratigraphic series, drawn by the researcher on the basis of the features that has to be highlighted. The observations are localized by means of manual measurements and a certain amount of subjectivity in log drawing is involved. These facts can prevent the log from being properly pinned to the real outcrop. Moreover, the integration of stratigraphic logs made by different researchers studying the same outcrop may be difficult. The exposure conditions of outcrops can change through time, to the point that they can become unaccessible or even be destroyed. In such a case, linking the stratigraphic log to its physical counterpart becomes impossible. This can be particularly relevant when a classical outcrop or even a GSSP is considered. A VOM may prove useful to tackle these issues, by providing a more objective stratigraphic reference for measurements and by preserving an outcrop through time as a visual representation, thus permitting reference and accurate comparison between observations made through time. Finally, a VOM itself may contain relevant stratigraphic information (e.g. scalar fields associated with the point cloud as intensity, rgb data or hyperspectral information from passive remote sensing devices). This information requires to be merged with geological data collected in the field, in a consistent and reproducible way. We present Vombat, a proof-of-concept of open-source software to illustrate some of the possibilities in terms of information storage, visualization and exploitation of outcrop stratigraphic information. Our solution integrates with CloudCompare, a software that permits to visualize and edit point clouds. A dedicated algorithm estimates stratigraphic attitudes from point cloud data, without the need of exposed planar bedding surfaces. These attitudes can be used to define a virtual stratigraphic section. Composite sections can then be realized defining stratigraphic constraints between different reference frames. Any observation can be displayed in a stratigraphic framework that is directly generated from a VOM. The virtual outcrop, the samples and the stratigraphic reference frames can be saved into an XML file. In the future, the adoption of a standard format (e.g. GeoSciML) will permit easier exchange of stratigraphic data among researchers. The software constitutes a first step towards the full exploitation of VOMs in stratigraphy, is stored at http://github.com/luca-penasa/vombat‏ and is open source. Comments and suggestions are most welcome and will help focusing and refining the software and its tools.

Compilation of Published Estimates of Annual Geocenter Motions Using Space Geodesy

NASA Technical Reports Server (NTRS)

Elosegui, P.

2005-01-01

The definition of the term "geocenter motion" depends on the adopted origin of the reference frame. Common reference frames used in Space Geodesy include: the center of mass of the whole Earth (CM), the center of mass of the Solid Earth without mass load (CE), and the center of figure of the outer surface of the Solid Earth (CF). There are two established definitions of the term geocenter: one, the vector offset of CF relative to CM and, two, the reverse, the vector offset of CM relative to CF. Obviously, their amplitude is the same and their phase differs by 180 deg. Following Dong et al. [2003], we label the first X(sub CF, sup CM) and the second X(sup CF, sup CM) (i.e., the superscript represents the frame, the subscript represents any point in the frame).

JPL VLBI Analysis Center IVS Annual Report for 2004

NASA Technical Reports Server (NTRS)

Jacobs, Chris

2005-01-01

This report describes the activities of the JPL VLBI analysis center for the year 2004. We continue to be celestial reference frame, terrestrial reference frame, earth orientation, and spacecraft navigation work using the VLBI technique. There are several areas of our work that are undergoing active development. In 2004 we demonstrated 1 mm level troposphere calibration on an intercontinental baseline. We detected our first X/Ka (8.4/32 GHz) VLBI fringes. We began to deploy Mark 5 recorders and to interface the Mark 5 units to our software correlator. We also have actively participated in the international VLBI community through our involvement in six papers at the February IVS meeting and by collaborating on a number of projects such as densifying the S/X celestial frame creating celestial frames at K (24 GHz) and Q-bands ($# GHz)>

Assessment of the possible contribution of space ties on-board GNSS satellites to the terrestrial reference frame

NASA Astrophysics Data System (ADS)

Bruni, Sara; Rebischung, Paul; Zerbini, Susanna; Altamimi, Zuheir; Errico, Maddalena; Santi, Efisio

2018-04-01

The realization of the international terrestrial reference frame (ITRF) is currently based on the data provided by four space geodetic techniques. The accuracy of the different technique-dependent materializations of the frame physical parameters (origin and scale) varies according to the nature of the relevant observables and to the impact of technique-specific errors. A reliable computation of the ITRF requires combining the different inputs, so that the strengths of each technique can compensate for the weaknesses of the others. This combination, however, can only be performed providing some additional information which allows tying together the independent technique networks. At present, the links used for that purpose are topometric surveys (local/terrestrial ties) available at ITRF sites hosting instruments of different techniques. In principle, a possible alternative could be offered by spacecrafts accommodating the positioning payloads of multiple geodetic techniques realizing their co-location in orbit (space ties). In this paper, the GNSS-SLR space ties on-board GPS and GLONASS satellites are thoroughly examined in the framework of global reference frame computations. The investigation focuses on the quality of the realized physical frame parameters. According to the achieved results, the space ties on-board GNSS satellites cannot, at present, substitute terrestrial ties in the computation of the ITRF. The study is completed by a series of synthetic simulations investigating the impact that substantial improvements in the volume and quality of SLR observations to GNSS satellites would have on the precision of the GNSS frame parameters.

Motion compensation and noise tolerance in phase-shifting digital in-line holography.

PubMed

Stenner, Michael D; Neifeld, Mark A

2006-05-15

We present a technique for phase-shifting digital in-line holography which compensates for lateral object motion. By collecting two frames of interference between object and reference fields with identical reference phase, one can estimate the lateral motion that occurred between frames using the cross-correlation. We also describe a very general linear framework for phase-shifting holographic reconstruction which minimizes additive white Gaussian noise (AWGN) for an arbitrary set of reference field amplitudes and phases. We analyze the technique's sensitivity to noise (AWGN, quantization, and shot), errors in the reference fields, errors in motion estimation, resolution, and depth of field. We also present experimental motion-compensated images achieving the expected resolution.

Noninertial coordinate time: A new concept affecting time standards, time transfers, and clock synchronization

NASA Technical Reports Server (NTRS)

Deines, Steven D.

1992-01-01

Relativity compensations must be made in precise and accurate measurements whenever an observer is accelerated. Although many believe the Earth-centered frame is sufficiently inertial, accelerations of the Earth, as evidenced by the tides, prove that it is technically a noninertial system for even an Earth-based observer. Using the constant speed of light, a set of fixed remote clocks in an inertial frame can be synchronized to a fixed master clock transmitting its time in that frame. The time on the remote clock defines the coordinate time at that coordinate position. However, the synchronization procedure for an accelerated frame is affected, because the distance between the master and remote clocks is altered due to the acceleration of the remote clock toward or away from the master clock during the transmission interval. An exact metric that converts observations from noninertial frames to inertial frames was recently derived. Using this metric with other physical relationships, a new concept of noninertial coordinate time is defined. This noninertial coordinate time includes all relativity compensations. This new issue raises several timekeeping issues, such as proper time standards, time transfer process, and clock synchronization, all in a noninertial frame such as Earth.

CASA-Mot technology: how results are affected by the frame rate and counting chamber.

PubMed

Bompart, Daznia; García-Molina, Almudena; Valverde, Anthony; Caldeira, Carina; Yániz, Jesús; Núñez de Murga, Manuel; Soler, Carles

2018-04-04

For over 30 years, CASA-Mot technology has been used for kinematic analysis of sperm motility in different mammalian species, but insufficient attention has been paid to the technical limitations of commercial computer-aided sperm analysis (CASA) systems. Counting chamber type and frame rate are two of the most important aspects to be taken into account. Counting chambers can be disposable or reusable, with different depths. In human semen analysis, reusable chambers with a depth of 10µm are the most frequently used, whereas for most farm animal species it is more common to use disposable chambers with a depth of 20µm . The frame rate was previously limited by the hardware, although changes in the number of images collected could lead to significant variations in some kinematic parameters, mainly in curvilinear velocity (VCL). A frame rate of 60 frames s-1 is widely considered to be the minimum necessary for satisfactory results. However, the frame rate is species specific and must be defined in each experimental condition. In conclusion, we show that the optimal combination of frame rate and counting chamber type and depth should be defined for each species and experimental condition in order to obtain reliable results.

The parametrization of radio source coordinates in VLBI and its impact on the CRF

NASA Astrophysics Data System (ADS)

Karbon, Maria; Heinkelmann, Robert; Mora-Diaz, Julian; Xu, Minghui; Nilsson, Tobias; Schuh, Harald

2016-04-01

Usually celestial radio sources in the celestial reference frame (CRF) catalog are divided in three categories: defining, special handling, and others. The defining sources are those used for the datum realization of the celestial reference frame, i.e. they are included in the No-Net-Rotation (NNR) constraints to maintain the axis orientation of the CRF, and are modeled with one set of totally constant coordinates. At the current level of precision, the choice of the defining sources has a significant effect on the coordinates. For the ICRF2 295 sources were chosen as defining sources, based on their geometrical distribution, statistical properties, and stability. The number of defining sources is a compromise between the reliability of the datum, which increases with the number of sources, and the noise which is introduced by each source. Thus, the optimal number of defining sources is a trade-off between reliability, geometry, and precision. In the ICRF2 only 39 of sources were sorted into the special handling group as they show large fluctuations in their position, therefore they are excluded from the NNR conditions and their positions are normally estimated for each VLBI session instead of as global parameters. All the remaining sources are classified as others. However, a large fraction of these unstable sources show other favorable characteristics, e.g. large flux density (brightness) and a long history of observations. Thus, it would prove advantageous including these sources into the NNR condition. However, the instability of these objects inhibit this. If the coordinate model of these sources would be extended, it would be possible to use these sources for the NNR condition as well. All other sources are placed in the "others" group. This is the largest group of sources, containing those which have not shown any very problematic behavior, but still do not fulfill the requirements for defining sources. Studies show that the behavior of each source can vary dramatically in time. Hence, each source would have to be modeled individually. Considering this, the shear amount of sources, in our study more than 600 are included, sets practical limitations. We decided to use the multivariate adaptive regression splines (MARS) procedure to parametrize the source coordinates, as they allow a great deal of automation as it combines recursive partitioning and spline fitting in an optimal way. The algorithm finds the ideal knot positions for the splines and thus the best number of polynomial pieces to fit the data. We investigate linear and cubic splines determined by MARS to "human" determined linear splines and their impact on the CRF. Within this work we try to answer the following questions: How can we find optimal criteria for the definition of the defining and unstable sources? What are the best polynomials for the individual categories? How much can we improve the CRF by extending the parametrization of the sources?

Behavioral model of visual perception and recognition

NASA Astrophysics Data System (ADS)

Rybak, Ilya A.; Golovan, Alexander V.; Gusakova, Valentina I.

1993-09-01

In the processes of visual perception and recognition human eyes actively select essential information by way of successive fixations at the most informative points of the image. A behavioral program defining a scanpath of the image is formed at the stage of learning (object memorizing) and consists of sequential motor actions, which are shifts of attention from one to another point of fixation, and sensory signals expected to arrive in response to each shift of attention. In the modern view of the problem, invariant object recognition is provided by the following: (1) separated processing of `what' (object features) and `where' (spatial features) information at high levels of the visual system; (2) mechanisms of visual attention using `where' information; (3) representation of `what' information in an object-based frame of reference (OFR). However, most recent models of vision based on OFR have demonstrated the ability of invariant recognition of only simple objects like letters or binary objects without background, i.e. objects to which a frame of reference is easily attached. In contrast, we use not OFR, but a feature-based frame of reference (FFR), connected with the basic feature (edge) at the fixation point. This has provided for our model, the ability for invariant representation of complex objects in gray-level images, but demands realization of behavioral aspects of vision described above. The developed model contains a neural network subsystem of low-level vision which extracts a set of primary features (edges) in each fixation, and high- level subsystem consisting of `what' (Sensory Memory) and `where' (Motor Memory) modules. The resolution of primary features extraction decreases with distances from the point of fixation. FFR provides both the invariant representation of object features in Sensor Memory and shifts of attention in Motor Memory. Object recognition consists in successive recall (from Motor Memory) and execution of shifts of attention and successive verification of the expected sets of features (stored in Sensory Memory). The model shows the ability of recognition of complex objects (such as faces) in gray-level images invariant with respect to shift, rotation, and scale.

Extending the ICRF to Higher Radio Frequencies

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Jones, D. L.; Lanyi, G. E.; Lowe, S. T.; Naudet, C. J.; Resch, G. M.; Steppe, J. A.; Zhang, L. D.; Ulvestad, J. S.; Taylor, G. B.

2002-01-01

The ICRF forms the basis for all astrometry including use as the inertial coordinate system for navigating deep space missions. This frame was defined using S/X-band observations over the past 20+ years. In January 2002, the VLBA approved our proposal for observing time to extend the ICRF to K-band (24 GHz) and Q-band (43 GHz). The first step will be observations at K- and Q-bands on a subset of ICRF sources. Eventually, K- and Q-band multi-epoch observations will be used to estimate positions, flux density and source structure for a large fraction of the current S/X-band ICRF source list. This work will benefit the radio astronomy community by extending the VLBA calibrator list at these bands. In the longer term, we would also like to extend the ICRF to Ka-band (32 GHz). A celestial reference frame will be needed at this frequency to support deep space navigation. A navigation demonstration is being considered for NASA's Mars 2005 mission. The initial K- and Q-band work will serve to identify candidate sources at Ka-band for use with that mission.

Transformation of Galilean satellite parameters to J2000

NASA Astrophysics Data System (ADS)

Lieske, J. H.

1998-09-01

The so-called galsat software has the capability of computing Earth-equatorial coordinates of Jupiter's Galilean satellies in an arbitrary reference frame, not just that of B1950. The 50 parameters which define the theory of motion of the Galilean satellites (Lieske 1977, Astron. Astrophys. 56, 333--352) could also be transformed in a manner such that the same galsat computer program can be employed to compute rectangular coordinates with their values being in the J2000 system. One of the input parameters (varepsilon_ {27}) is related to the obliquity of the ecliptic and its value is normally zero in the B1950 frame. If that parameter is changed from 0 to -0.0002771, and if other input parameters are changed in a prescribed manner, then the same galsat software can be employed to produce ephemerides on the J2000 system for any of the ephemerides which employ the galsat parameters, such as those of Arlot (1982), Vasundhara (1994) and Lieske. In this paper we present the parameters whose values must be altered in order for the software to produce coordinates directly in the J2000 system.

Framing Vision: An Examination of Framing, Sensegiving, and Sensemaking during a Change Initiative

ERIC Educational Resources Information Center

Hamilton, William

2016-01-01

The purpose of this short article is to review the findings from an instrumental case study that examines how a college president used what this article refers to as "frame alignment processes" to mobilize internal and external support for a college initiative--one that achieved success under the current president. Specifically, I…

Frequent Frames as a Cue for Grammatical Categories in Child Directed Speech

ERIC Educational Resources Information Center

Mintz, Toben H.

2003-01-01

This paper introduces the notion of frequent frames, distributional patterns based on co-occurrence patterns of words in sentences, then investigates the usefulness of this information in grammatical categorization. A frame is defined as two jointly occurring words with one word intervening. Qualitative and quantitative results from distributional…

Extending F10.7’s Time Resolution to Capture Solar Flare Phenomena

DTIC Science & Technology

2008-07-01

Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 REFERENCES ...accelera- tion, (iii) maximum power is emitted in a direction perpendicular to the acceleration, and (iv) the radiation from protons is insignificant...then is P = 2 3 e2 c3 v2⊥e 2B2γ2 m2ec 2 . (2.19) In the electron reference frame, the power emitted is dipolar and in the rest frame, the power is

How and Why to Do VLBI on GPS

NASA Technical Reports Server (NTRS)

Dickey, J. M.

2010-01-01

In order to establish the position of the center of mass of the Earth in the International Celestial Reference Frame, observations of the Global Positioning Satellite (GPS) constellation using the IVS network are important. With a good frame-tie between the coordinates of the IVS telescopes and nearby GPS receivers, plus a common local oscillator reference signal, it should be possible to observe and record simultaneously signals from the astrometric calibration sources and the GPS satellites. The standard IVS solution would give the atmospheric delay and clock offsets to use in analysis of the GPS data. Correlation of the GPS signals would then give accurate orbital parameters of the satellites in the ICRF reference frame, i.e., relative to the positions of the astrometric sources. This is particularly needed to determine motion of the center of mass of the earth along the rotation axis.

Users manual for a one-dimensional Lagrangian transport model

USGS Publications Warehouse

Schoellhamer, D.H.; Jobson, H.E.

1986-01-01

A Users Manual for the Lagrangian Transport Model (LTM) is presented. The LTM uses Lagrangian calculations that are based on a reference frame moving with the river flow. The Lagrangian reference frame eliminates the need to numerically solve the convective term of the convection-diffusion equation and provides significant numerical advantages over the more commonly used Eulerian reference frame. When properly applied, the LTM can simulate riverine transport and decay processes within the accuracy required by most water quality studies. The LTM is applicable to steady or unsteady one-dimensional unidirectional flows in fixed channels with tributary and lateral inflows. Application of the LTM is relatively simple and optional capabilities improve the model 's convenience. Appendices give file formats and three example LTM applications that include the incorporation of the QUAL II water quality model 's reaction kinetics into the LTM. (Author 's abstract)

Nursing home staff members' subjective frames of reference on residents' achievement of ego integrity: A Q-methodology study.

PubMed

Lim, Sun-Young; Chang, Sung-Ok

2018-01-01

To discover the structure of the frames of reference for nursing home staff members' subjective judgment of residents' achievement of ego integrity. Q-methodology was applied. Twenty-eight staff members who were working in a nursing home sorted 34 Q-statements into the shape of a normal distribution. A centroid factor analysis and varimax rotation, using the PQ-method program, revealed four factors: identifying clues to residents' positive acceptance of their whole life span, identifying residents' ways of enjoying their current life, referencing residents' attitudes and competencies toward harmonious relationships, and identifying residents' integrated efforts to establish self-esteem. These subjective frames of reference need to be investigated in order to improve the relationships with nursing home residents and their quality of life. Consequently, the fundamental monitoring tools to help staff members make subjective judgments can be formed. © 2017 Japan Academy of Nursing Science.

What constitutes an efficient reference frame for vision?

PubMed Central

Tadin, Duje; Lappin, Joseph S.; Blake, Randolph; Grossman, Emily D.

2015-01-01

Vision requires a reference frame. To what extent does this reference frame depend on the structure of the visual input, rather than just on retinal landmarks? This question is particularly relevant to the perception of dynamic scenes, when keeping track of external motion relative to the retina is difficult. We tested human subjects’ ability to discriminate the motion and temporal coherence of changing elements that were embedded in global patterns and whose perceptual organization was manipulated in a way that caused only minor changes to the retinal image. Coherence discriminations were always better when local elements were perceived to be organized as a global moving form than when they were perceived to be unorganized, individually moving entities. Our results indicate that perceived form influences the neural representation of its component features, and from this, we propose a new method for studying perceptual organization. PMID:12219092

Research Activities for the DORIS Contribution to the Next International Terrestrial Reference Frame

NASA Technical Reports Server (NTRS)

Soudarin, L.; Moreaux, G.; Lemoine, F.; Willis, P.; Stepanek, P.; Otten, M.; Govind, R.; Kuzin, S.; Ferrage, P.

2012-01-01

For the preparation of ITRF2008, the IDS processed data from 1993 to 2008, including data from TOPEX/Poseidon, the SPOT satellites and Envisat in the weekly solutions. Since the development of ITRF2008, the IDS has been engaged in a number of efforts to try and improve the reference frame solutions. These efforts include (i) assessing the contribution of the new DORIS satellites, Jason-2 and Cryosat2 (2008-2011), (ii) individually analyzing the DORIS satellite contributions to geocenter and scale, and (iii) improving orbit dynamics (atmospheric loading effects, satellite surface force modeling. . . ). We report on the preliminary results from these research activities, review the status of the IDS combination which is now routinely generated from the contributions of the IDS analysis centers, and discuss the prospects for continued improvement in the DORIS contribution to the next international reference frame.

Seasonal station variations in the Vienna VLBI terrestrial reference frame VieTRF16a

NASA Astrophysics Data System (ADS)

Krásná, Hana; Böhm, Johannes; Madzak, Matthias

2017-04-01

The special analysis center of the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS) at TU Wien (VIE) routinely analyses the VLBI measurements and estimates its own Terrestrial Reference Frame (TRF) solutions. We present our latest solution VieTRF16a (1979.0 - 2016.5) computed with the software VieVS version 3.0. Several recent updates of the software have been applied, e.g., the estimation of annual and semi-annual station variations as global parameters. The VieTRF16a is determined in the form of the conventional model (station position and its linear velocity) simultaneously with the celestial reference frame and Earth orientation parameters. In this work, we concentrate on the seasonal station variations in the residual time series and compare our TRF with the three combined TRF solutions ITRF2014, DTRF2014 and JTRF2014.

KALREF—A Kalman filter and time series approach to the International Terrestrial Reference Frame realization

NASA Astrophysics Data System (ADS)

Wu, Xiaoping; Abbondanza, Claudio; Altamimi, Zuheir; Chin, T. Mike; Collilieux, Xavier; Gross, Richard S.; Heflin, Michael B.; Jiang, Yan; Parker, Jay W.

2015-05-01

The current International Terrestrial Reference Frame is based on a piecewise linear site motion model and realized by reference epoch coordinates and velocities for a global set of stations. Although linear motions due to tectonic plates and glacial isostatic adjustment dominate geodetic signals, at today's millimeter precisions, nonlinear motions due to earthquakes, volcanic activities, ice mass losses, sea level rise, hydrological changes, and other processes become significant. Monitoring these (sometimes rapid) changes desires consistent and precise realization of the terrestrial reference frame (TRF) quasi-instantaneously. Here, we use a Kalman filter and smoother approach to combine time series from four space geodetic techniques to realize an experimental TRF through weekly time series of geocentric coordinates. In addition to secular, periodic, and stochastic components for station coordinates, the Kalman filter state variables also include daily Earth orientation parameters and transformation parameters from input data frames to the combined TRF. Local tie measurements among colocated stations are used at their known or nominal epochs of observation, with comotion constraints applied to almost all colocated stations. The filter/smoother approach unifies different geodetic time series in a single geocentric frame. Fragmented and multitechnique tracking records at colocation sites are bridged together to form longer and coherent motion time series. While the time series approach to TRF reflects the reality of a changing Earth more closely than the linear approximation model, the filter/smoother is computationally powerful and flexible to facilitate incorporation of other data types and more advanced characterization of stochastic behavior of geodetic time series.

The Egyptian geomagnetic reference field to the Epoch, 2010.0

NASA Astrophysics Data System (ADS)

Deebes, H. A.; Abd Elaal, E. M.; Arafa, T.; Lethy, A.; El Emam, A.; Ghamry, E.; Odah, H.

2017-06-01

The present work is a compilation of two tasks within the frame of the project ;Geomagnetic Survey & Detailed Geomagnetic Measurements within the Egyptian Territory; funded by the ;Science and Technology Development Fund agency (STDF);. The National Research Institute of Astronomy and Geophysics (NRIAG), has conducted a new extensive land geomagnetic survey that covers the whole Egyptian territory. The field measurements have been done at 3212 points along all the asphalted roads, defined tracks, and ill-defined tracks in Egypt; with total length of 11,586 km. In the present work, the measurements cover for the first time new areas as: the southern eastern borders of Egypt including Halayeb and Shlatin, the Quattara depresion in the western desert, and the new roads between Farafra and Baharia oasis. Also marine geomagnetic survey have been applied for the first time in Naser lake. Misallat and Abu-Simble geomagnetic observatories have been used to reduce the field data to the Epoch 2010. During the field measurements, whenever possible, the old stations occupied by the previous observers have been re-occupied to determine the secular variations at these points. The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF) and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF) 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF) 2010 is indicated.

Examination of global correlations in ground deformation for terrestrial reference frame estimation

NASA Astrophysics Data System (ADS)

Chin, T. M.; Abbondanza, C.; Argus, D. F.; Gross, R. S.; Heflin, M. B.; Parker, J. W.; Wu, X.

2016-12-01

The KALman filter for REFerence frames (KALREF, Wu et al. 2015) has been developed to produce terrestrial reference frame (TRF) solutions. TRFs consist of precise position coordinates and velocity vectors of terrestrial reference sites (with the geocenter as the origin) along with the Earth orientation parameters, and they are produced by combining decades worth of space geodetic data using site tie data. To perform the combination, KALREF relies on stochastic models of the geophysical processes that are causing the Earth's surface to deform and reference sites to be displaced. We are investigating application of the GRACE data to improve the KALREF stochastic models by determining spatial statistics of the deformation of the Earth's surface caused by mass loading. A potential target of improvement is the non-uniform distribution of the geodetic observation sites, which can introduce bias in TRF estimates of the geocenter. The global and relatively uniform coverage of the GRACE measurements is expected to be free of such bias and allow us to improve physical realism of the stochastic model. For such a goal, we examine the spatial correlations in ground deformation derived from several GRACE data sets.[Wu et al. 2015: Journal of Geophysical Research (Solid Earth) 120:3775-3802

Determining the locations of the various CIRC recording format information blocks (user data blocks, C2 and C1 words and EFM frames) on a recorded compact disc

NASA Technical Reports Server (NTRS)

Howe, Dennis G.

1993-01-01

Just prior to its being EFM modulated (i.e., converted to eight-to-fourteen channel data by the EFM encoder) and written to a Compact Disc (CD), information that passes through the CIRC Block Encoder is grouped into 33-byte blocks referred to as EFM frames. Twenty four of the bytes that make up a given EFM frame are user data that was input into the CIRC encoder at various (different) times, 4 of the bytes of this same EFM frame were created by the C2 ECC encoder (each at a different time), and another 4 were created by the C1 ECC encoder (again, each at a different time). The one remaining byte of the given EFM frame, which is known as the EFM frame C&D (for Control & Display) byte, carries information that identifies which portion of the current disc program track the given EFM frame belongs to and also specifies the location of the given EFM frame on the disc (in terms of a time stamp that has a resolution of l/75th second, or 98 EFM frames). (Note: since the program track and time information is stored as a 98-byte word, a logical group consisting of 98 consecutive EFM frames must be read, and their respective C&D bytes must be catenated and decoded, before the program track identification and time position information that pertains to the entire block of 98 EFM frames can be obtained.) The C&D byte is put at the start (0th byte) of an EFM frame in real time; its placement completes the construction of the EFM frame - it is assigned just before the EFM frame enters the EFM encoder. Four distinct blocks of data are referred to: 24-byte User Input Data Blocks; 28-byte C2 words; 32-byte C1 words; and 33-byte EFM frames.

A-frame model for metaphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilpatrick, W.

1982-01-01

While literal language is successfully being subjected to automatic analysis, metaphors remain intractable. Using Minsky's frame theory the metaphoric process is viewed as a copying of stereotypic terminal clusters from the frames of the 1 degrees and 2 degrees terms of the metaphor. Stereotypic values from the two original frames share equal status in this new frame, while non-stereotypic values from the two will be kept separate for possible use in metaphoric extension. The a-frame analysis is illustrated by application to non-literary novel metaphors. Frames provide the quantity of information needed for interpretation. Certain frame values are marked as stereotypic.more » Creativity is realized by the construction of a new a-frame, and the tension is realized by the presence in a single a-frame of both shared stereotypic and discrete non-stereotypic values. 10 references.« less

Optical seismic sensor systems and methods

DOEpatents

Beal, A. Craig; Cummings, Malcolm E.; Zavriyev, Anton; Christensen, Caleb A.; Lee, Keun

2015-12-08

Disclosed is an optical seismic sensor system for measuring seismic events in a geological formation, including a surface unit for generating and processing an optical signal, and a sensor device optically connected to the surface unit for receiving the optical signal over an optical conduit. The sensor device includes at least one sensor head for sensing a seismic disturbance from at least one direction during a deployment of the sensor device within a borehole of the geological formation. The sensor head includes a frame and a reference mass attached to the frame via at least one flexure, such that movement of the reference mass relative to the frame is constrained to a single predetermined path.

Plate and Plume Flux: Constraints for paleomagnetic reference frames and interpretation of deep mantle seismic heterogeneity. (Invited)

NASA Astrophysics Data System (ADS)

Bunge, H.; Schuberth, B. S.; Shephard, G. E.; Müller, D.

2010-12-01

Plate and plume flow are dominant modes of mantle convection, as pointed out by Geoff Davies early on. Driven, respectively, from a cold upper and a hot lower thermal boundary layer these modes are now sufficiently well imaged by seismic tomographers to exploit the thermal boundary layer concept as an effective tool in exploring two long standing geodynamic problems. One relates to the choice of an absolute reference frame in plate tectonic reconstructions. Several absolute reference frames have been proposed over the last decade, including those based on hotspot tracks displaying age progression and assuming either fixity or motion, as well as palaeomagnetically-based reference frames, a subduction reference frame and hybrid versions. Each reference frame implies a particular history of the location of subduction zones through time and thus the evolution of mantle heterogeneity via mixing of subducted slab material in the mantle. Here we compare five alternative absolute plate motion models in terms of their consequences for deep mantle structure. Taking global paleo-plate boundaries and plate velocities back to 140 Ma derived from the new plate tectonic reconstruction software GPlates and assimilating them into vigorous 3-D spherical mantle circulation models, we infer geodynamic mantle heterogeneity and compare it to seismic tomography for each absolute rotation model. We also focus on the challenging problem of interpreting deep mantle seismic heterogeneity in terms of thermal and compositional variations. Using published thermodynamically self-consistent mantle mineralogy models in the pyrolite composition, we find strong plume flux from the CMB, with a high temperature contrast (on the order of 1000 K) across the lower thermal boundary layer is entirely sufficient to explain elastic heterogeneity in the deep mantle for a number of quantitative measures. A high excess temperatures of +1000--1500 K for plumes in the lowermost mantle is particularly important in understanding the strong seismic velocity reduction mapped by tomography in low-velocity bodies of the deep mantle, as this produces significant negative anomalies of shear wave velocity of up to -4%. We note, however, that our results do not account for the curious observation of seismic anti-correlation, which appears difficult to explain in any case. Our results provide important constraints for the integration of plate tectonics and mantle dynamics and their use in forward and inverse geodynamic mantle models.

The Influence of Framing on Risky Decisions: A Meta-analysis.

PubMed

Kühberger

1998-07-01

In framing studies, logically equivalent choice situations are differently described and the resulting preferences are studied. A meta-analysis of framing effects is presented for risky choice problems which are framed either as gains or as losses. This evaluates the finding that highlighting the positive aspects of formally identical problems does lead to risk aversion and that highlighting their equivalent negative aspects does lead to risk seeking. Based on a data pool of 136 empirical papers that reported framing experiments with nearly 30,000 participants, we calculated 230 effect sizes. Results show that the overall framing effect between conditions is of small to moderate size and that profound differences exist between research designs. Potentially relevant characteristics were coded for each study. The most important characteristics were whether framing is manipulated by changing reference points or by manipulating outcome salience, and response mode (choice vs. rating/judgment). Further important characteristics were whether options differ qualitatively or quantitatively in risk, whether there is one or multiple risky events, whether framing is manipulated by gain/loss or by task-responsive wording, whether dependent variables are measured between- or within- subjects, and problem domains. Sample (students vs. target populations) and unit of analysis (individual vs. group) was not influential. It is concluded that framing is a reliable phenomenon, but that outcome salience manipulations, which constitute a considerable amount of work, have to be distinguished from reference point manipulations and that procedural features of experimental settings have a considerable effect on effect sizes in framing experiments. Copyright 1998 Academic Press.

The Celestial Reference Frame at X/Ka-band (8.4/32 GHz)

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Heflin, M. B.; Skjerve, L. J.; Sovers, O. J.; Garcia-Miro, C.; Moll, V. E.; Horiuchi, S.

2011-01-01

A celestial reference frame at X/Ka-band (8.4/32 GHz) has been constructed using fifty-one 24-hour sessions with the Deep Space Network. We report on observations which have detected 436 sources covering the full 24 hours of right ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of 200 micro-arcsec in a cos delta and 290 micro-arcsec in delta. There is evidence for zonal errors at the 100 micro-arcsec level. Known errors include limited SNR, lack of phase calibration, troposphere mismodelling, and limited southern geometry. The motivations for extending the ICRF to frequencies above 8 GHz are to access more compact source morphology for improved frame stability, to provide calibrators for phase referencing, and to support spacecraft navigation at Ka-band.

The Celestial Reference Frame at X/Ka-band (8.4/32 GHz)

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Heflin, M. B.; Skjerve, L. J.; Sovers, O. J.; Garcia-Miro, C.; Moll, V. E.; Horiuchi, S.

2010-01-01

A celestial reference frame at X/Kaband (8.4/32 GHz) has been constructed using fiftyone 24-hour sessions with the Deep Space Network. We report on observations which have detected 436 sources covering the full 24 hours of right ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of 200 micro-arcsec ( mu as) in alpha cos delta and 290 mu as in delta. There is evidence for zonal errors at the 100 mu as level. Known errors include limited SNR, lack of phase calibration, troposphere mismodelling, and limited southern geometry. The motivations for extending the ICRF to frequencies above 8 GHz are to access more compact source morphology for improved frame stability, to provide calibrators for phase referencing, and to support spacecraft navigation at Ka-band.

Postglacial Rebound from VLBI Geodesy: On Establishing Vertical Reference

NASA Technical Reports Server (NTRS)

Argus, Donald F.

1996-01-01

Difficulty in establishing a reference frame fixed to the earth's interior complicates the measurement of the vertical (radial) motions of the surface. I propose that a useful reference frame for vertical motions is that found by minimizing differences between vertical motions observed with VLBI [Ma and Ryan] and predictions from postglacial rebound predictions [Peltier]. The optimal translation of the geocenter is 1.7mm/year toward 36degN, 111degE when determined from the motions of 10 VLBI sites. This translation gives a better fit of observations to predictions than does the VLBI reference frame used by Ma and Ryan, but the improvement is statistically insignificant. The root mean square of differences decreases 20% to 0.73 mm/yr and the correlation coefficient increases from 0.76 to 0.87. Postglacial rebound is evident in the uplift of points in Sweden and Ontario that were beneath the ancient ice sheets of Fennoscandia and Canada, and in the subsidence of points in the northeastern U.S., Germany, and Alaska that were around the periphery of the ancient ice sheets.

Effects of tectonic plate deformation on the geodetic reference frame of Mexico

NASA Astrophysics Data System (ADS)

Gonzalez Franco, G. A.; Avalos, D.; Esquivel, R.

2013-05-01

Positioning for geodetic applications is commonly determined at one observation epoch, but tectonic drift and tectonic deformation cause the coordinates to be different for any other epoch. Finding the right coordinates at a different epoch from that of the observation time is necessary in Mexico in order to comply the official reference frame, which requires all coordinates to be referred to the standard epoch 2010.0. Available models of horizontal movement in rigid tectonic plates are used to calculate the displacement of coordinates; however for a portion of Mexico these models fail because of miss-modeled regional deformation, decreasing the quality of users' data transformed to the standard epoch. In this work we present the progress achieved in measuring actual horizontal motion towards an improved modeling of horizontal displacements for some regions. Miss-modeled velocities found are as big as 23mm/a, affecting significantly applications like cadastral and geodetic control. Data from a large set of GNSS permanent stations in Mexico is being analyzed to produce the preliminary model of horizontal crustal movement that will be used to minimize distortions of the reference frame.

Osculating Relative Orbit Elements Resulting from Chief Eccentricity and J2 Perturbing Forces

DTIC Science & Technology

2011-03-01

significant importance to the analytical investigation in this study and is described in depth in Section 3.1.1. There do exist approaches to mapping the...necessary to introduce the environment which the majority of models describe. 2.2.1 Inertial Reference Frame. A geocentric reference frame will be used for...closest approach , modifying the period and minima locations of the radial and in-track components. This change impacts the periodicity of the radial

Covariance Analysis of Vision Aided Navigation by Bootstrapping

DTIC Science & Technology

2012-03-22

vision aided navigation. The aircraft uses its INS estimate to geolocate ground features, track those features to aid the INS, and using that aided...development of the 2-D case, including the dynamics and measurement model development, the state space representation and the use of the Kalman filter ...reference frame. This reference frame has its origin located somewhere on an A/C. Normally the origin is set at the A/C center of gravity to allow the use

Large perceptual distortions of locomotor action space occur in ground-based coordinates: Angular expansion and the large-scale horizontal-vertical illusion.

PubMed

Klein, Brennan J; Li, Zhi; Durgin, Frank H

2016-04-01

What is the natural reference frame for seeing large-scale spatial scenes in locomotor action space? Prior studies indicate an asymmetric angular expansion in perceived direction in large-scale environments: Angular elevation relative to the horizon is perceptually exaggerated by a factor of 1.5, whereas azimuthal direction is exaggerated by a factor of about 1.25. Here participants made angular and spatial judgments when upright or on their sides to dissociate egocentric from allocentric reference frames. In Experiment 1, it was found that body orientation did not affect the magnitude of the up-down exaggeration of direction, suggesting that the relevant orientation reference frame for this directional bias is allocentric rather than egocentric. In Experiment 2, the comparison of large-scale horizontal and vertical extents was somewhat affected by viewer orientation, but only to the extent necessitated by the classic (5%) horizontal-vertical illusion (HVI) that is known to be retinotopic. Large-scale vertical extents continued to appear much larger than horizontal ground extents when observers lay sideways. When the visual world was reoriented in Experiment 3, the bias remained tied to the ground-based allocentric reference frame. The allocentric HVI is quantitatively consistent with differential angular exaggerations previously measured for elevation and azimuth in locomotor space. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Large perceptual distortions of locomotor action space occur in ground-based coordinates: Angular expansion and the large-scale horizontal-vertical illusion

PubMed Central

Klein, Brennan J.; Li, Zhi; Durgin, Frank H.

2015-01-01

What is the natural reference frame for seeing large-scale spatial scenes in locomotor action space? Prior studies indicate an asymmetric angular expansion in perceived direction in large-scale environments: Angular elevation relative to the horizon is perceptually exaggerated by a factor of 1.5, whereas azimuthal direction is exaggerated by a factor of about 1.25. Here participants made angular and spatial judgments when upright or on their sides in order to dissociate egocentric from allocentric reference frames. In Experiment 1 it was found that body orientation did not affect the magnitude of the up-down exaggeration of direction, suggesting that the relevant orientation reference frame for this directional bias is allocentric rather than egocentric. In Experiment 2, the comparison of large-scale horizontal and vertical extents was somewhat affected by viewer orientation, but only to the extent necessitated by the classic (5%) horizontal-vertical illusion (HVI) that is known to be retinotopic. Large-scale vertical extents continued to appear much larger than horizontal ground extents when observers lay sideways. When the visual world was reoriented in Experiment 3, the bias remained tied to the ground-based allocentric reference frame. The allocentric HVI is quantitatively consistent with differential angular exaggerations previously measured for elevation and azimuth in locomotor space. PMID:26594884

On the ability to provide evaluative comments: further explorations of children's narrative competencies.

PubMed

Bamberg, M; Damrad-Frye, R

1991-10-01

This study investigated the changing functions of evaluative devices in children's narratives. The evaluative devices included (a) references to 'frames of mind', particularly to emotions, (b) character speech, (c) 'hedges', (d) negative qualifiers, and (e) causal connectors. Narratives were elicited from a 24-picture story book. The subjects were three groups of native English-speaking Americans (12 per group): five- and nine-year-old children and college undergraduate students. A quantitative comparison revealed that (i) adults used evaluative devices three times as often as five-year-olds, and two-and-a-half times as often as the nine-year-old children; (ii) adults used significantly more references to 'frames of mind' and 'hedges' than the children; and (iii) whereas five-year-olds used each evaluative type equally often, nine-year-olds and adults used references to 'frames of mind' significantly more than the other four evaluation types. A second analysis, focusing specifically on the discourse functions of references to 'frames of mind' revealed that, early on, this particular device is used to express a local evaluative perspective on particular events, while with increasing age it is used to signal the hierarchial organization of the story events. These findings are discussed with regard to two non-linguistic developmental achievements, the formation of event schemas and the formation of a theory of mind.

Quantum image coding with a reference-frame-independent scheme

NASA Astrophysics Data System (ADS)

Chapeau-Blondeau, François; Belin, Etienne

2016-07-01

For binary images, or bit planes of non-binary images, we investigate the possibility of a quantum coding decodable by a receiver in the absence of reference frames shared with the emitter. Direct image coding with one qubit per pixel and non-aligned frames leads to decoding errors equivalent to a quantum bit-flip noise increasing with the misalignment. We show the feasibility of frame-invariant coding by using for each pixel a qubit pair prepared in one of two controlled entangled states. With just one common axis shared between the emitter and receiver, exact decoding for each pixel can be obtained by means of two two-outcome projective measurements operating separately on each qubit of the pair. With strictly no alignment information between the emitter and receiver, exact decoding can be obtained by means of a two-outcome projective measurement operating jointly on the qubit pair. In addition, the frame-invariant coding is shown much more resistant to quantum bit-flip noise compared to the direct non-invariant coding. For a cost per pixel of two (entangled) qubits instead of one, complete frame-invariant image coding and enhanced noise resistance are thus obtained.

Categorizing Words Using "Frequent Frames": What Cross-Linguistic Analyses Reveal about Distributional Acquisition Strategies

ERIC Educational Resources Information Center

Chemla, Emmanuel; Mintz, Toben H.; Bernal, Savita; Christophe, Anne

2009-01-01

Mintz (2003 ) described a distributional environment called a frame, defined as the co-occurrence of two context words with one intervening target word. Analyses of English child-directed speech showed that words that fell within any frequently occurring frame consistently belonged to the same grammatical category (e.g. noun, verb, adjective,…

Modeling moving systems with RELAP5-3D

DOE PAGES

Mesina, G. L.; Aumiller, David L.; Buschman, Francis X.; ...

2015-12-04

RELAP5-3D is typically used to model stationary, land-based reactors. However, it can also model reactors in other inertial and accelerating frames of reference. By changing the magnitude of the gravitational vector through user input, RELAP5-3D can model reactors on a space station or the moon. The field equations have also been modified to model reactors in a non-inertial frame, such as occur in land-based reactors during earthquakes or onboard spacecraft. Transient body forces affect fluid flow in thermal-fluid machinery aboard accelerating crafts during rotational and translational accelerations. It is useful to express the equations of fluid motion in the acceleratingmore » frame of reference attached to the moving craft. However, careful treatment of the rotational and translational kinematics is required to accurately capture the physics of the fluid motion. Correlations for flow at angles between horizontal and vertical are generated via interpolation where no experimental studies or data exist. The equations for three-dimensional fluid motion in a non-inertial frame of reference are developed. As a result, two different systems for describing rotational motion are presented, user input is discussed, and an example is given.« less

Comparison of z-known GRBs with the Main Groups of Bright BATSE Events

NASA Technical Reports Server (NTRS)

Mitrofanov, Igor G.; Sanin, Anton B.; Anfimov, Dmitrij S.; Litvak, Maxim L.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey N.; Preece, Robert D.; Meegan, Charles A.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

The small reference sample of six BATSE gamma-ray bursts with known redshifts from optical afterglows is compared with a comparison group of the 218 brightest BATSE bursts. These two groups are shown to be consistent both with respect to the distributions of the spectral peak parameter in the observer's frame and also with respect to the distributions of the frame-independent cosmological invariant parameter (CIP). Using the known values of the redshifts z for the reference sample, the rest-frame distribution of spectral parameters is built. The de-redshifted distribution of the spectral parameters of the reference sample is compared with distribution of these parameters for the comparison group after de-redshifting by the factor 1/(1+z), with z a free parameter. Requiring consistency between these two distributions produces a collective estimation of the best fitting redshifts z for the comparison group, z=1.8--3.6. These values can be considered as the average cosmological redshift of the sources of the brightest BATSE bursts. The most probable value of the peak energy of the spectrum in the rest frame is 920 keV, close to the rest mass of an electron-positron pair.

JPEG XS-based frame buffer compression inside HEVC for power-aware video compression

NASA Astrophysics Data System (ADS)

Willème, Alexandre; Descampe, Antonin; Rouvroy, Gaël.; Pellegrin, Pascal; Macq, Benoit

2017-09-01

With the emergence of Ultra-High Definition video, reference frame buffers (FBs) inside HEVC-like encoders and decoders have to sustain huge bandwidth. The power consumed by these external memory accesses accounts for a significant share of the codec's total consumption. This paper describes a solution to significantly decrease the FB's bandwidth, making HEVC encoder more suitable for use in power-aware applications. The proposed prototype consists in integrating an embedded lightweight, low-latency and visually lossless codec at the FB interface inside HEVC in order to store each reference frame as several compressed bitstreams. As opposed to previous works, our solution compresses large picture areas (ranging from a CTU to a frame stripe) independently in order to better exploit the spatial redundancy found in the reference frame. This work investigates two data reuse schemes namely Level-C and Level-D. Our approach is made possible thanks to simplified motion estimation mechanisms further reducing the FB's bandwidth and inducing very low quality degradation. In this work, we integrated JPEG XS, the upcoming standard for lightweight low-latency video compression, inside HEVC. In practice, the proposed implementation is based on HM 16.8 and on XSM 1.1.2 (JPEG XS Test Model). Through this paper, the architecture of our HEVC with JPEG XS-based frame buffer compression is described. Then its performance is compared to HM encoder. Compared to previous works, our prototype provides significant external memory bandwidth reduction. Depending on the reuse scheme, one can expect bandwidth and FB size reduction ranging from 50% to 83.3% without significant quality degradation.

The Experimental Research on Seismic Capacity of the Envelope Systems with Steel Frame

NASA Astrophysics Data System (ADS)

Li, Jiuyang; Wang, Bingbing; Li, Hengxu

2017-09-01

In this paper, according to the present application situation of the external envelope systems steel frame in the severe cold region, the stuffed composite wall panels are improved, the flexible connection with the steel frame is designed, the reduced scale specimens are made, the seismic capacity test is made and some indexes of the envelope systems such as bearing capacity, energy consumption and ductility, etc. are compared, which provide reference for the development and application of the steel frame envelope systems.

Effect of general relativity on a near-Earth satellite in the geocentric and barycentric reference frames

NASA Technical Reports Server (NTRS)

Ries, J. C.; Huang, C.; Watkins, M. M.

1988-01-01

Whether one uses a solar-system barycentric frame or a geocentric frame when including the general theory of relativity in orbit determinations for near-Earth satellites, the results should be equivalent to some limiting accuracy. The purpose of this paper is to clarify the effects of relativity in each frame and to demonstrate their equivalence through the analysis of real laser-tracking data. A correction to the conventional barycentric equations of motion is shown to be required.

Results from the JPL IGS Analysis Center IGS14 Reprocessing Campaign

NASA Astrophysics Data System (ADS)

Ries, P. A.; Amiri, N.; Heflin, M. B.; Sakumura, C.; Sibois, A. E.; Sibthorpe, A.; David, M. W.

2017-12-01

The JPL IGS analysis center has begun a campaign to reprocess GPS orbits and clocks in the IGS14 reference frame. Though the new frame is only a few millimeters offset from the previous IGb08 frame, a reprocessing is required for consistent use of the new frame due to a change in the satellite phase center offsets between the frames. We will present results on the reprocessing campaign from 2002 to present in order to evaluate any effects caused by the new frame. We also create long-term time-series and periodograms of translation, rotation, and scale parameters to see if there is any divergence between the frames. We will also process long-term PPP time series and derived velocities for a well-distributed set of stations in each frame to compare with the published frame offsets.

The Influence of the Terrestrial Reference Frame on Studies of Sea Level Change

NASA Astrophysics Data System (ADS)

Nerem, R. S.; Bar-Sever, Y. E.; Haines, B. J.; Desai, S.; Heflin, M. B.

2015-12-01

The terrestrial reference frame (TRF) provides the foundation for the accurate monitoring of sea level using both ground-based (tide gauges) and space-based (satellite altimetry) techniques. For the latter, tide gauges are also used to monitor drifts in the satellite instruments over time. The accuracy of the terrestrial reference frame (TRF) is thus a critical component for both types of sea level measurements. The TRF is central to the formation of geocentric sea-surface height (SSH) measurements from satellite altimeter data. The computed satellite orbits are linked to a particular TRF via the assumed locations of the ground-based tracking systems. The manner in which TRF errors are expressed in the orbit solution (and thus SSH) is not straightforward, and depends on the models of the forces underlying the satellite's motion. We discuss this relationship, and provide examples of the systematic TRF-induced errors in the altimeter derived sea-level record. The TRF is also crucial to the interpretation of tide-gauge measurements, as it enables the separation of vertical land motion from volumetric changes in the water level. TRF errors affect tide gauge measurements through GNSS estimates of the vertical land motion at each tide gauge. This talk will discuss the current accuracy of the TRF and how errors in the TRF impact both satellite altimeter and tide gauge sea level measurements. We will also discuss simulations of how the proposed Geodetic Reference Antenna in SPace (GRASP) satellite mission could reduce these errors and revolutionize how reference frames are computed in general.

22. CRUNCH BOARD #2 HANGAR BAY FRAME 100 STARBOARD SIDETERM ...

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

22. CRUNCH BOARD #2 HANGAR BAY FRAME 100 STARBOARD SIDE-TERM CRUNCH REFERS TO HANGAR DECK MISHAPS WHICH RESULTED IN DAMAGE TO AIRCRAFT. - U.S.S. HORNET, Puget Sound Naval Shipyard, Sinclair Inlet, Bremerton, Kitsap County, WA

Echocardiogram video summarization

NASA Astrophysics Data System (ADS)

Ebadollahi, Shahram; Chang, Shih-Fu; Wu, Henry D.; Takoma, Shin

2001-05-01

This work aims at developing innovative algorithms and tools for summarizing echocardiogram videos. Specifically, we summarize the digital echocardiogram videos by temporally segmenting them into the constituent views and representing each view by the most informative frame. For the segmentation we take advantage of the well-defined spatio- temporal structure of the echocardiogram videos. Two different criteria are used: presence/absence of color and the shape of the region of interest (ROI) in each frame of the video. The change in the ROI is due to different modes of echocardiograms present in one study. The representative frame is defined to be the frame corresponding to the end- diastole of the heart cycle. To locate the end-diastole we track the ECG of each frame to find the exact time the time- marker on the ECG crosses the peak of the end-diastole we track the ECG of each frame to find the exact time the time- marker on the ECG crosses the peak of the R-wave. The corresponding frame is chosen to be the key-frame. The entire echocardiogram video can be summarized into either a static summary, which is a storyboard type of summary and a dynamic summary, which is a concatenation of the selected segments of the echocardiogram video. To the best of our knowledge, this if the first automated system for summarizing the echocardiogram videos base don visual content.

The GLAS Algorithm Theoretical Basis Document for Laser Footprint Location (Geolocation) and Surface Profiles

NASA Technical Reports Server (NTRS)

Shutz, Bob E.; Urban, Timothy J.

2014-01-01

This ATBD summarizes (and links with other ATBDs) the elements used to obtain the geolocated GLAS laser spot location, with respect to the Earth Center of Mass. Because of the approach used, the reference frame used to express the geolocation is linked to the reference frame used for POD and PAD, which are related to the ITRF. The geolocated spot coordinates (which includes the elevation or height, with respect to an adopted reference ellipsoid) is the inferred position of the laser spot, since the spot location is not directly measured. This document also summarizes the GLAS operation time periods.

Trajectory Generation by Piecewise Spline Interpolation

DTIC Science & Technology

1976-04-01

Lx) -a 0 + atx + aAx + x (21)0 1 2 3 and the coefficients are obtained from Equation (20) as ao m fl (22)i al " fi, (23) S3(fi + I f ) 2fj + fj+ 1 (24...reference frame to the vehicle fixed frame is pTO’ 0TO’ OTO’ *TO where a if (gZv0 - A >- 0 aCI (64) - azif (gzv0- AzvO < 0 These rotations may be...velocity frame axes directions (velocity frame from the output frame) aO, al , a 2 , a 3 Coefficients of the piecewise cubic polynomials [B ] Tridiagonal

Rotating full- and reduced-dimensional quantum chemical models of molecules

NASA Astrophysics Data System (ADS)

Fábri, Csaba; Mátyus, Edit; Császár, Attila G.

2011-02-01

A flexible protocol, applicable to semirigid as well as floppy polyatomic systems, is developed for the variational solution of the rotational-vibrational Schrödinger equation. The kinetic energy operator is expressed in terms of curvilinear coordinates, describing the internal motion, and rotational coordinates, characterizing the orientation of the frame fixed to the nonrigid body. Although the analytic form of the kinetic energy operator might be very complex, it does not need to be known a priori within this scheme as it is constructed automatically and numerically whenever needed. The internal coordinates can be chosen to best represent the system of interest and the body-fixed frame is not restricted to an embedding defined with respect to a single reference geometry. The features of the technique mentioned make it especially well suited to treat large-amplitude nuclear motions. Reduced-dimensional rovibrational models can be defined straightforwardly by introducing constraints on the generalized coordinates. In order to demonstrate the flexibility of the protocol and the associated computer code, the inversion-tunneling of the ammonia (14NH3) molecule is studied using one, two, three, four, and six active vibrational degrees of freedom, within both vibrational and rovibrational variational computations. For example, the one-dimensional inversion-tunneling model of ammonia is considered also for nonzero rotational angular momenta. It turns out to be difficult to significantly improve upon this simple model. Rotational-vibrational energy levels are presented for rotational angular momentum quantum numbers J = 0, 1, 2, 3, and 4.

Corrections to the Thomson cross section caused by relativistic effects and by the presence of the drift velocity of a classical charged particle in the field of a monochromatic plane wave

NASA Astrophysics Data System (ADS)

Perestoronin, A. V.

2017-03-01

An approach to the solution of the relativistic problem of the motion of a classical charged particle in the field of a monochromatic plane wave with an arbitrary polarization (linear, circular, or elliptic) is proposed. It is based on the analysis of the 4-vector equation of motion of the charged particle together with the 4-vector and tensor equations for the components of the electromagnetic field tensor of a monochromatic plane wave. This approach provides analytical expressions for the time-averaged square of the 4-acceleration of the charge, as well as for the averaged values of any quantities periodic in the time of the reference frame. Expressions for the integral power of scattered radiation, which is proportional to the time-averaged square of the 4-acceleration of the charge, and for the integral scattering cross section, which is the ratio of the power of scattered radiation to the intensity of incident radiation, are obtained for an arbitrary inertial reference frame. An expression for the scattering cross section, which coincides with the known results at the circular and linear polarizations of the incident waves and describes the case of elliptic polarization of the incident wave, is obtained for the reference frame where the charged particle is on average at rest. An expression for the scattering cross section including relativistic effects and the nonzero drift velocity of a particle in this system is obtained for the laboratory reference frame, where the initial velocity of the charged particle is zero. In the case of the circular polarization of the incident wave, the scattering cross section in the laboratory frame is equal to the Thompson cross section.

Global plate motion frames: Toward a unified model

NASA Astrophysics Data System (ADS)

Torsvik, Trond H.; Müller, R. Dietmar; van der Voo, Rob; Steinberger, Bernhard; Gaina, Carmen

2008-09-01

Plate tectonics constitutes our primary framework for understanding how the Earth works over geological timescales. High-resolution mapping of relative plate motions based on marine geophysical data has followed the discovery of geomagnetic reversals, mid-ocean ridges, transform faults, and seafloor spreading, cementing the plate tectonic paradigm. However, so-called "absolute plate motions," describing how the fragments of the outer shell of the Earth have moved relative to a reference system such as the Earth's mantle, are still poorly understood. Accurate absolute plate motion models are essential surface boundary conditions for mantle convection models as well as for understanding past ocean circulation and climate as continent-ocean distributions change with time. A fundamental problem with deciphering absolute plate motions is that the Earth's rotation axis and the averaged magnetic dipole axis are not necessarily fixed to the mantle reference system. Absolute plate motion models based on volcanic hot spot tracks are largely confined to the last 130 Ma and ideally would require knowledge about the motions within the convecting mantle. In contrast, models based on paleomagnetic data reflect plate motion relative to the magnetic dipole axis for most of Earth's history but cannot provide paleolongitudes because of the axial symmetry of the Earth's magnetic dipole field. We analyze four different reference frames (paleomagnetic, African fixed hot spot, African moving hot spot, and global moving hot spot), discuss their uncertainties, and develop a unifying approach for connecting a hot spot track system and a paleomagnetic absolute plate reference system into a "hybrid" model for the time period from the assembly of Pangea (˜320 Ma) to the present. For the last 100 Ma we use a moving hot spot reference frame that takes mantle convection into account, and we connect this to a pre-100 Ma global paleomagnetic frame adjusted 5° in longitude to smooth the reference frame transition. Using plate driving force arguments and the mapping of reconstructed large igneous provinces to core-mantle boundary topography, we argue that continental paleolongitudes can be constrained with reasonable confidence.

[The function, activity and participation: the occupational reintegration].

PubMed

Zampolini, Mauro

2015-01-01

The return to work is a significant outcome after amputation. To reach this goal it is necessary to measure properly this process. Unfortunately, for amputee, we have different scales but often focused on specific groups of problems The International Classification of funtioning (ICF) can constitute the frame of reference where to converge scales available and according to which define problems related to disability. For the person amputated the theme of the return to work arises differently for the conditions traumatic and non-traumatic. For the first return to work is a priority given the younger age. For the latter, given the advanced age, the return to work is likely to be a measure of the success of rehabilitation is not particularly relevant.

Suggested notation conventions for rotational seismology

USGS Publications Warehouse

Evans, J.R.

2009-01-01

We note substantial inconsistency among authors discussing rotational motions observed with inertial seismic sensors (and much more so in the broader topic of rotational phenomena). Working from physics and other precedents, we propose standard terminology and a preferred reference frame for inertial sensors (Fig. 1) that may be consistently used in discussions of both finite and infinitesimal observed rotational and translational motions in seismology and earthquake engineering. The scope of this article is limited to observations because there are significant differences in the analysis of finite and infinitesimal rotations, though such discussions should remain compatible with those presented here where possible. We recommend the general use of the notation conventions presented in this tutorial, and we recommend that any deviations or alternatives be explicitly defined.

Mount mechanisms for the Saturn 5/Apollo mobile launcher at John F. Kennedy Space Center

NASA Technical Reports Server (NTRS)

Balke, H. A.

1975-01-01

A support system was designed to resist hurricane wind loads at the launch pad and to allow the supported structural frame to expand and contract freely under wide ranges of temperature. This system consists of six mount mechanisms devised to meet the previously stated requirements plus a load-carrying capacity for each of 3.2-million kilograms (7-million pounds) downward and 1.6-million kilograms (3.5-million pounds) upward. A similar but lighter system of six mount mechanisms was designed for use in the sheltered environment of the vehicle assembly building. Each requirement and design result is discussed, and each mount mechanism is defined by location and type with references to visual presentations.

Frames of reference for helicopter electronic maps - The relevance of spatial cognition and componential analysis

NASA Technical Reports Server (NTRS)

Harwood, Kelly; Wickens, Christopher D.

1991-01-01

Computer-generated map displays for NOE and low-level helicopter flight were formed according to prior research on maps, navigational problem solving, and spatial cognition in large-scale environments. The north-up map emphasized consistency of object location, wheareas, the track-up map emphasized map-terrain congruency. A component analysis indicates that different cognitive components, e.g., orienting and absolute object location, are supported to varying degrees by properties of different frames of reference.

Self- and Other-Referent Criteria of Career Success.

ERIC Educational Resources Information Center

Heslin, Peter A.

2003-01-01

Business students (n=71) evaluated their career success thus far. Framed by social comparison theory, results showed that 68% used other-referent criteria to assess their success. Participants who believed that ability and personality are fixed attributes had greater reliance on other-referent criteria. (Contains 100 references.) (SK)

Full-Frame Reference for Test Photo of Moon

NASA Image and Video Library

2005-09-10

This pair of views shows how little of the full image frame was taken up by the Moon in test images taken Sept. 8, 2005, by the High Resolution Imaging Science Experiment HiRISE camera on NASA Mars Reconnaissance Orbiter.

The Multimission Image Processing Laboratory's virtual frame buffer interface

NASA Technical Reports Server (NTRS)

Wolfe, T.

1984-01-01

Large image processing systems use multiple frame buffers with differing architectures and vendor supplied interfaces. This variety of architectures and interfaces creates software development, maintenance and portability problems for application programs. Several machine-dependent graphics standards such as ANSI Core and GKS are available, but none of them are adequate for image processing. Therefore, the Multimission Image Processing laboratory project has implemented a programmer level virtual frame buffer interface. This interface makes all frame buffers appear as a generic frame buffer with a specified set of characteristics. This document defines the virtual frame uffer interface and provides information such as FORTRAN subroutine definitions, frame buffer characteristics, sample programs, etc. It is intended to be used by application programmers and system programmers who are adding new frame buffers to a system.

TIGA Tide Gauge Data Reprocessing at GFZ

NASA Astrophysics Data System (ADS)

Deng, Zhiguo; Schöne, Tilo; Gendt, Gerd

2014-05-01

To analyse the tide gauge measurements for the purpose of global long-term sea level change research a well-defined absolute reference frame is required by oceanographic community. To create such frame the data from a global GNSS network located at or near tide gauges are processed. For analyzing the GNSS data on a preferably continuous basis the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring Working Group (TIGA-WG) is responsible. As one of the TIGA Analysis Centers the German Research Centre for Geosciences (GFZ) is contributing to the IGS TIGA Reprocessing Campaign. The solutions of the TIGA Reprocessing Campaign will also contribute to 2nd IGS Data Reprocessing Campaign with GFZ IGS reprocessing solution. After the first IGS reprocessing finished in 2010 some improvements were implemented into the latest GFZ software version EPOS.P8: reference frame IGb08 based on ITRF2008, antenna calibration igs08.atx, geopotential model (EGM2008), higher-order ionospheric effects, new a priori meteorological model (GPT2), VMF mapping function, and other minor improvements. GPS data of the globally distributed tracking network of 794 stations for the time span from 1994 until end of 2012 are used for the TIGA reprocessing. To handle such large network a new processing strategy is developed and described in detail. In the TIGA reprocessing the GPS@TIGA data are processed in precise point positioning (PPP) mode to clean data using the IGS reprocessing orbit and clock products. To validate the quality of the PPP coordinate results the rates of 80 GPS@TIGA station vertical movement are estimated from the PPP results using Maximum Likelihood Estimation (MLE) method. The rates are compared with the solution of University of LaRochelle Consortium (ULR) (named ULR5). 56 of the 80 stations have a difference of the vertical velocities below 1 mm/yr. The error bars of PPP rates are significant larger than those of ULR5, which indicates large time correlated noise in the PPP solutions.

Defining biophysical reference conditions for dynamics river systems: an Alaskan example

NASA Astrophysics Data System (ADS)

Pess, G. R.

2008-12-01

Defining reference conditions for dynamic river ecosystems is difficult for two reasons. First long-term, persistent anthropogenic influences such as land development, harvest of biological resources, and invasive species have resulted in degraded, reduced, and simplified ecological communities and associated habitats. Second, river systems that have not been altered through human disturbance rarely have a long-term dataset on ecological conditions. However there are exceptions which can help us define the dynamic nature of river ecosystems. One large-scale exception is the Wood River system in Bristol Bay, Alaska, where habitat and salmon populations have not been altered by anthropogenic influences such as land development, hatchery production, and invasive species. In addition, the one major anthropogenic disturbance, salmon (Oncorhynchus spp.) harvest, has been quantified and regulated since its inception. First, we examined the variation in watershed and stream habitat characteristics across the Wood River system. We then compared these stream habitat characteristics with data that was collected in the 1950s. Lastly, we examined the correlation between pink (Oncorhynchus gorbuscha), chum (O. keta), and Chinook (O. tshawytscha), and sockeye salmon (O. nerka), and habitat characteristics in the Wood River system using four decades of data on salmon. We found that specific habitat attributes such as stream channel wetted width, depth, cover type, and the proportion of spawnable area were similar to data collected in the 1950s. Greater stream habitat variation occurred among streams than over time. Salmon occurrence and abundance, however was more temporal and spatially variable. The occurrence of pink and chum salmon increased from the 1970's to the present in the Wood River system, while sockeye abundance has fluctuated with changes in ocean conditions. Pink, Chinook and chum salmon ranged from non-existent to episodic to abundantly perennial, while sockeye dominated all streams in the Wood River system. One main trend was the frequency of occurrence and abundance of pink, Chinook, and chum salmon increased with watershed drainage area and stream depth and, to a lesser extent, decreased with sockeye salmon density. Conversely, sockeye salmon densities decreased with watershed drainage area and stream depth. Wood river habitat was temporally stable and spatially variable, thus identifying the suite of stream channel types that occur and identifying reference states for each is critical to capture reference conditions. Wood River biological reference states need to be established over a longer time frame than physical attributes because of the large-scale temporal variability that is forced by climatic conditions and larger scale spatially- explicit trends. Thus biological reference states for the Wood River system need to be defined with multiple streams, similar to developing reference states for different stream channel types, in order to capture the range of biological variability.

Expected Improvements in VLBI Measurements of the Earth's Orientation

NASA Technical Reports Server (NTRS)

Ma, Chopo

2003-01-01

Measurements of the Earth s orientation since the 1970s using space geodetic techniques have provided a continually expanding and improving data set for studies of the Earth s structure and the distribution of mass and angular momentum. The accuracy of current one-day measurements is better than 100 microarcsec for the motion of the pole with respect to the celestial and terrestrial reference frames and better than 3 microsec for the rotation around the pole. VLBI uniquely provides the three Earth orientation parameters (nutation and UTI) that relate the Earth to the extragalactic celestial reference frame. The accuracy and resolution of the VLBI Earth orientation time series can be expected to improve substantially in the near future because of refinements in the realization of the celestial reference frame, improved modeling of the troposphere and non-linear station motions, larger observing networks, optimized scheduling, deployment of disk-based Mark V recorders, full use of Mark IV capabilities, and e-VLBI. More radical future technical developments will be discussed.

Functional correlates of the lateral and medial entorhinal cortex: objects, path integration and local-global reference frames.

PubMed

Knierim, James J; Neunuebel, Joshua P; Deshmukh, Sachin S

2014-02-05

The hippocampus receives its major cortical input from the medial entorhinal cortex (MEC) and the lateral entorhinal cortex (LEC). It is commonly believed that the MEC provides spatial input to the hippocampus, whereas the LEC provides non-spatial input. We review new data which suggest that this simple dichotomy between 'where' versus 'what' needs revision. We propose a refinement of this model, which is more complex than the simple spatial-non-spatial dichotomy. MEC is proposed to be involved in path integration computations based on a global frame of reference, primarily using internally generated, self-motion cues and external input about environmental boundaries and scenes; it provides the hippocampus with a coordinate system that underlies the spatial context of an experience. LEC is proposed to process information about individual items and locations based on a local frame of reference, primarily using external sensory input; it provides the hippocampus with information about the content of an experience.

Point cloud registration from local feature correspondences-Evaluation on challenging datasets.

PubMed

Petricek, Tomas; Svoboda, Tomas

2017-01-01

Registration of laser scans, or point clouds in general, is a crucial step of localization and mapping with mobile robots or in object modeling pipelines. A coarse alignment of the point clouds is generally needed before applying local methods such as the Iterative Closest Point (ICP) algorithm. We propose a feature-based approach to point cloud registration and evaluate the proposed method and its individual components on challenging real-world datasets. For a moderate overlap between the laser scans, the method provides a superior registration accuracy compared to state-of-the-art methods including Generalized ICP, 3D Normal-Distribution Transform, Fast Point-Feature Histograms, and 4-Points Congruent Sets. Compared to the surface normals, the points as the underlying features yield higher performance in both keypoint detection and establishing local reference frames. Moreover, sign disambiguation of the basis vectors proves to be an important aspect in creating repeatable local reference frames. A novel method for sign disambiguation is proposed which yields highly repeatable reference frames.

Number of revolutions of a particle around a black hole: Is it infinite or finite?

NASA Astrophysics Data System (ADS)

Pavlov, Yuri V.; Zaslavskii, Oleg B.

2018-01-01

We consider a particle falling into a rotating black hole. Such a particle makes an infinite number of revolutions n from the viewpoint of a remote observer who uses the Boyer-Lindquist type of coordinates. We examine the behavior of n when it is measured with respect to a local reference frame that also rotates due to dragging effect of spacetime. The crucial point consists here in the observation that for a nonextremal black hole, the leading contributions to n from a particle itself and the reference frame have the same form being in fact universal, so that divergences mutually cancel. As a result, the relative number of revolutions turns out to be finite. For the extremal black hole this is not so, n can be infinite. Different choices of the local reference frame are considered, the results turn out to be the same qualitatively. For illustration, we discuss two explicit examples—rotation in the flat spacetime and in the Kerr metric.

Planning of an Experiment for VLBI Tracking of GNSS Satellites

NASA Technical Reports Server (NTRS)

Tornatore, Vincenza; Hass, Ruediger; Molera, Guifre; Pogrebenko, Sergei

2010-01-01

As a preparation for future possible orbit determination of global navigation satellite system (GNSS) satellites by VLBI observations an initial three-station experiment was planned and performed in January 2009. The goal was to get first experience and to verify the feasibility of using the method for accurate satellite tracking. GNSS orbits related to a satellite constellation can be expressed in the Terrestrial Reference Frame. A comparison with orbit results that might be obtained by VLBI can give valuable information on how the GNSS reference frame and the VLBI reference frame are linked. We present GNSS transmitter specifications and experimental results of the observations of some GLONASS satellites together with evaluations for the expected signal strengths at telescopes. The satellite flux densities detected on the Earth s surface are very high. The narrow bandwidth of the GNSS signal partly compensates for potential problems at the receiving stations, and signal attenuation is necessary. Attempts to correlate recorded data have been performed with different software.

Functional correlates of the lateral and medial entorhinal cortex: objects, path integration and local–global reference frames

PubMed Central

Knierim, James J.; Neunuebel, Joshua P.; Deshmukh, Sachin S.

2014-01-01

The hippocampus receives its major cortical input from the medial entorhinal cortex (MEC) and the lateral entorhinal cortex (LEC). It is commonly believed that the MEC provides spatial input to the hippocampus, whereas the LEC provides non-spatial input. We review new data which suggest that this simple dichotomy between ‘where’ versus ‘what’ needs revision. We propose a refinement of this model, which is more complex than the simple spatial–non-spatial dichotomy. MEC is proposed to be involved in path integration computations based on a global frame of reference, primarily using internally generated, self-motion cues and external input about environmental boundaries and scenes; it provides the hippocampus with a coordinate system that underlies the spatial context of an experience. LEC is proposed to process information about individual items and locations based on a local frame of reference, primarily using external sensory input; it provides the hippocampus with information about the content of an experience. PMID:24366146

Framing of task performance strategies: effects on performance in a multiattribute dynamic decision making environment.

PubMed

Nygren, T E

1997-09-01

It is well documented that the way a static choice task is "framed" can dramatically alter choice behavior, often leading to observable preference reversals. This framing effect appears to result from perceived changes in the nature or location of a person's initial reference point, but it is not clear how framing effects might generalize to performance on dynamic decision making tasks that are characterized by high workload, time constraints, risk, or stress. A study was conducted to examine the hypothesis that framing can introduce affective components to the decision making process and can influence, either favorably (positive frame) or adversely (negative frame), the implementation and use of decision making strategies in dynamic high-workload environments. Results indicated that negative frame participants were significantly impaired in developing and employing a simple optimal decision strategy relative to a positive frame group. Discussion focuses on implications of these results for models of dynamic decision making.

Patch-based frame interpolation for old films via the guidance of motion paths

NASA Astrophysics Data System (ADS)

Xia, Tianran; Ding, Youdong; Yu, Bing; Huang, Xi

2018-04-01

Due to improper preservation, traditional films will appear frame loss after digital. To deal with this problem, this paper presents a new adaptive patch-based method of frame interpolation via the guidance of motion paths. Our method is divided into three steps. Firstly, we compute motion paths between two reference frames using optical flow estimation. Then, the adaptive bidirectional interpolation with holes filled is applied to generate pre-intermediate frames. Finally, using patch match to interpolate intermediate frames with the most similar patches. Since the patch match is based on the pre-intermediate frames that contain the motion paths constraint, we show a natural and inartificial frame interpolation. We test different types of old film sequences and compare with other methods, the results prove that our method has a desired performance without hole or ghost effects.

A Possible Approach to Inclusion of Space and Time in Frame Fields of Quantum Representations of Real and Complex Numbers

DOE PAGES

Benioff, Paul

2009-01-01

Tmore » his work is based on the field of reference frames based on quantum representations of real and complex numbers described in other work. Here frame domains are expanded to include space and time lattices. Strings of qukits are described as hybrid systems as they are both mathematical and physical systems. As mathematical systems they represent numbers. As physical systems in each frame the strings have a discrete Schrodinger dynamics on the lattices. he frame field has an iterative structure such that the contents of a stage j frame have images in a stage j - 1 (parent) frame. A discussion of parent frame images includes the proposal that points of stage j frame lattices have images as hybrid systems in parent frames. he resulting association of energy with images of lattice point locations, as hybrid systems states, is discussed. Representations and images of other physical systems in the different frames are also described.« less

Torque ripple reduction of brushless DC motor based on adaptive input-output feedback linearization.

PubMed

Shirvani Boroujeni, M; Markadeh, G R Arab; Soltani, J

2017-09-01

Torque ripple reduction of Brushless DC Motors (BLDCs) is an interesting subject in variable speed AC drives. In this paper at first, a mathematical expression for torque ripple harmonics is obtained. Then for a non-ideal BLDC motor with known harmonic contents of back-EMF, calculation of desired reference current amplitudes, which are required to eliminate some selected harmonics of torque ripple, are reviewed. In order to inject the reference harmonic currents to the motor windings, an Adaptive Input-Output Feedback Linearization (AIOFBL) control is proposed, which generates the reference voltages for three phases voltage source inverter in stationary reference frame. Experimental results are presented to show the capability and validity of the proposed control method and are compared with the vector control in Multi-Reference Frame (MRF) and Pseudo-Vector Control (P-VC) method results. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Application of the Undifferenced GNSS Precise Positioning in Determining Coordinates in National Reference Frames

NASA Astrophysics Data System (ADS)

Krzan, Grzegorz; Stępniak, Katarzyna

2017-09-01

In high-accuracy positioning using GNSS, the most common solution is still relative positioning using double-difference observations of dual-frequency measurements. An increasingly popular alternative to relative positioning are undifferenced approaches, which are designed to make full use of modern satellite systems and signals. Positions referenced to global International Terrestrial Reference Frame (ITRF2008) obtained from Precise Point Positioning (PPP) or Undifferenced (UD) network solutions have to be transformed to national (regional) reference frame, which introduces additional bases related to the transformation process. In this paper, satellite observations from two test networks using different observation time series were processed. The first test concerns the positioning accuracy from processing one year of dual-frequency GPS observations from 14 EUREF Permanent Network (EPN) stations using NAPEOS 3.3.1 software. The results were transformed into a national reference frame (PL-ETRF2000) and compared to positions from an EPN cumulative solution, which was adopted as the true coordinates. Daily observations were processed using PPP and UD multi-station solutions to determine the final accuracy resulting from satellite positioning, the transformation to national coordinate systems and Eurasian intraplate plate velocities. The second numerical test involved similar processing strategies of post-processing carried out using different observation time series (30 min., 1 hour, 2 hours, daily) and different classes of GNSS receivers. The centimeter accuracy of results presented in the national coordinate system satisfies the requirements of many surveying and engineering applications.

Exploiting the gain-modulation mechanism in parieto-motor neurons: application to visuomotor transformations and embodied simulation.

PubMed

Mahé, Sylvain; Braud, Raphaël; Gaussier, Philippe; Quoy, Mathias; Pitti, Alexandre

2015-02-01

The so-called self-other correspondence problem in imitation demands to find the transformation that maps the motor dynamics of one partner to our own. This requires a general purpose sensorimotor mechanism that transforms an external fixation-point (partner's shoulder) reference frame to one's own body-centered reference frame. We propose that the mechanism of gain-modulation observed in parietal neurons may generally serve these types of transformations by binding the sensory signals across the modalities with radial basis functions (tensor products) on the one hand and by permitting the learning of contextual reference frames on the other hand. In a shoulder-elbow robotic experiment, gain-field neurons (GF) intertwine the visuo-motor variables so that their amplitude depends on them all. In situations of modification of the body-centered reference frame, the error detected in the visuo-motor mapping can serve then to learn the transformation between the robot's current sensorimotor space and the new one. These situations occur for instance when we turn the head on its axis (visual transformation), when we use a tool (body modification), or when we interact with a partner (embodied simulation). Our results defend the idea that the biologically-inspired mechanism of gain modulation found in parietal neurons can serve as a basic structure for achieving nonlinear mapping in spatial tasks as well as in cooperative and social functions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Shifting attention in viewer- and object-based reference frames after unilateral brain injury.

PubMed

List, Alexandra; Landau, Ayelet N; Brooks, Joseph L; Flevaris, Anastasia V; Fortenbaugh, Francesca C; Esterman, Michael; Van Vleet, Thomas M; Albrecht, Alice R; Alvarez, Bryan D; Robertson, Lynn C; Schendel, Krista

2011-06-01

The aims of the present study were to investigate the respective roles that object- and viewer-based reference frames play in reorienting visual attention, and to assess their influence after unilateral brain injury. To do so, we studied 16 right hemisphere injured (RHI) and 13 left hemisphere injured (LHI) patients. We used a cueing design that manipulates the location of cues and targets relative to a display comprised of two rectangles (i.e., objects). Unlike previous studies with patients, we presented all cues at midline rather than in the left or right visual fields. Thus, in the critical conditions in which targets were presented laterally, reorienting of attention was always from a midline cue. Performance was measured for lateralized target detection as a function of viewer-based (contra- and ipsilesional sides) and object-based (requiring reorienting within or between objects) reference frames. As expected, contralesional detection was slower than ipsilesional detection for the patients. More importantly, objects influenced target detection differently in the contralesional and ipsilesional fields. Contralesionally, reorienting to a target within the cued object took longer than reorienting to a target in the same location but in the uncued object. This finding is consistent with object-based neglect. Ipsilesionally, the means were in the opposite direction. Furthermore, no significant difference was found in object-based influences between the patient groups (RHI vs. LHI). These findings are discussed in the context of reference frames used in reorienting attention for target detection. Published by Elsevier Ltd.

Behavioral Investigation on the Frames of Reference Involved in Visuomotor Transformations during Peripheral Arm Reaching

PubMed Central

Pelle, Gina; Perrucci, Mauro Gianni; Galati, Gaspare; Fattori, Patrizia; Galletti, Claudio; Committeri, Giorgia

2012-01-01

Background Several psychophysical experiments found evidence for the involvement of gaze-centered and/or body-centered coordinates in arm-movement planning and execution. Here we aimed at investigating the frames of reference involved in the visuomotor transformations for reaching towards visual targets in space by taking target eccentricity and performing hand into account. Methodology/Principal Findings We examined several performance measures while subjects reached, in complete darkness, memorized targets situated at different locations relative to the gaze and/or to the body, thus distinguishing between an eye-centered and a body-centered frame of reference involved in the computation of the movement vector. The errors seem to be mainly affected by the visual hemifield of the target, independently from its location relative to the body, with an overestimation error in the horizontal reaching dimension (retinal exaggeration effect). The use of several target locations within the perifoveal visual field allowed us to reveal a novel finding, that is, a positive linear correlation between horizontal overestimation errors and target retinal eccentricity. In addition, we found an independent influence of the performing hand on the visuomotor transformation process, with each hand misreaching towards the ipsilateral side. Conclusions While supporting the existence of an internal mechanism of target-effector integration in multiple frames of reference, the present data, especially the linear overshoot at small target eccentricities, clearly indicate the primary role of gaze-centered coding of target location in the visuomotor transformation for reaching. PMID:23272180

Changes in Rod and Frame Test Scores Recorded in Schoolchildren during Development – A Longitudinal Study

PubMed Central

Bagust, Jeff; Docherty, Sharon; Haynes, Wayne; Telford, Richard; Isableu, Brice

2013-01-01

The Rod and Frame Test has been used to assess the degree to which subjects rely on the visual frame of reference to perceive vertical (visual field dependence- independence perceptual style). Early investigations found children exhibited a wide range of alignment errors, which reduced as they matured. These studies used a mechanical Rod and Frame system, and presented only mean values of grouped data. The current study also considered changes in individual performance. Changes in rod alignment accuracy in 419 school children were measured using a computer-based Rod and Frame test. Each child was tested at school Grade 2 and retested in Grades 4 and 6. The results confirmed that children displayed a wide range of alignment errors, which decreased with age but did not reach the expected adult values. Although most children showed a decrease in frame dependency over the 4 years of the study, almost 20% had increased alignment errors suggesting that they were becoming more frame-dependent. Plots of individual variation (SD) against mean error allowed the sample to be divided into 4 groups; the majority with small errors and SDs; a group with small SDs, but alignments clustering around the frame angle of 18°; a group showing large errors in the opposite direction to the frame tilt; and a small number with large SDs whose alignment appeared to be random. The errors in the last 3 groups could largely be explained by alignment of the rod to different aspects of the frame. At corresponding ages females exhibited larger alignment errors than males although this did not reach statistical significance. This study confirms that children rely more heavily on the visual frame of reference for processing spatial orientation cues. Most become less frame-dependent as they mature, but there are considerable individual differences. PMID:23724139

Solution of steady and unsteady transonic-vortex flows using Euler and full-potential equations

NASA Technical Reports Server (NTRS)

Kandil, Osama A.; Chuang, Andrew H.; Hu, Hong

1989-01-01

Two methods are presented for inviscid transonic flows: unsteady Euler equations in a rotating frame of reference for transonic-vortex flows and integral solution of full-potential equation with and without embedded Euler domains for transonic airfoil flows. The computational results covered: steady and unsteady conical vortex flows; 3-D steady transonic vortex flow; and transonic airfoil flows. The results are in good agreement with other computational results and experimental data. The rotating frame of reference solution is potentially efficient as compared with the space fixed reference formulation with dynamic gridding. The integral equation solution with embedded Euler domain is computationally efficient and as accurate as the Euler equations.

Isla Guadalupe, Mexico (GUAX, SCIGN/PBO) a Relative Constraint for California Borderland and Northern Gulf of California Motions.

NASA Astrophysics Data System (ADS)

Gonzalez-Garcia, J. J.

2004-12-01

Using ITRF2000 as a common reference frame link, I analyzed survey mode and permanent GPS published results, together with SOPAC public data and results (http://sopac.ucsd.edu), in order to evaluate relative present day crustal deformation in California and northern Mexico. The crustal velocity field of Mexico (Marquez-Azua and DeMets, 2003) obtained from continuous GPS measurements conducted by Instituto Nacional de Geografia e Informatica (INEGI) for 1993-2001, was partially used. The preferred model for an instantaneous rigid motion between North-America and Pacific plates (NAPA), is obtained using results of Isla Guadalupe GPS surveys (1991-2002) giving a new constraint for Pacific plate (PA) motion (Gonzalez-Garcia et al., 2003). It produces an apparent reduction of 1 mm/yr in the absolute motion in the border zone between PA and North-America (NA) plates in this region, as compared with other GPS models (v.g. Prawirodirdjo and Bock, 2004); and it is 3 mm/yr higher than NNRNUVEL-1A. In the PA reference frame, westernmost islands from San Francisco (FARB), Los Angeles (MIG1), and Ensenada (GUAX); give current residuals of 1.8, 1.7 and 0.9 mm/yr and azimuths that are consistent with local tectonic setting, respectively. In the NA reference frame, besides the confirmation of 2 mm/yr E-W extension for the southern Basin and Range province in northern Mexico; a present day deformation rate of 40.5 mm/yr between San Felipe, Baja California (SFBC) and Hermosillo, Sonora, is obtained. This rate agrees with a 6.3 to 6.7 Ma for the "initiation of a full sea-floor spreading" in the northern Gulf of California. SFBC has a 7 mm/yr motion in the PA reference frame, giving then, a full NAPA theoretical absolute motion of 47.5 mm/yr. For Puerto Penasco, Sonora (PENA) there is a NAPA motion of 46.2 mm/yr and a residual of 1.2 mm/yr in the NA reference frame, this site is located only 75 km to the northeast from the Wagner basin center. For southern Isla Guadalupe (GUAX) there is 51.8 mm/yr in the NAPA reference frame. Finally full present day NAPA motion at the Alarcon Rise must be only 50.1 ±0.2 mm/yr in agreement with the lower limit of the NAPA "geological" model obtained by DeMets and Dixon (1999).

Speech coding, reconstruction and recognition using acoustics and electromagnetic waves

DOEpatents

Holzrichter, J.F.; Ng, L.C.

1998-03-17

The use of EM radiation in conjunction with simultaneously recorded acoustic speech information enables a complete mathematical coding of acoustic speech. The methods include the forming of a feature vector for each pitch period of voiced speech and the forming of feature vectors for each time frame of unvoiced, as well as for combined voiced and unvoiced speech. The methods include how to deconvolve the speech excitation function from the acoustic speech output to describe the transfer function each time frame. The formation of feature vectors defining all acoustic speech units over well defined time frames can be used for purposes of speech coding, speech compression, speaker identification, language-of-speech identification, speech recognition, speech synthesis, speech translation, speech telephony, and speech teaching. 35 figs.

Speech coding, reconstruction and recognition using acoustics and electromagnetic waves

DOEpatents

Holzrichter, John F.; Ng, Lawrence C.

1998-01-01

The use of EM radiation in conjunction with simultaneously recorded acoustic speech information enables a complete mathematical coding of acoustic speech. The methods include the forming of a feature vector for each pitch period of voiced speech and the forming of feature vectors for each time frame of unvoiced, as well as for combined voiced and unvoiced speech. The methods include how to deconvolve the speech excitation function from the acoustic speech output to describe the transfer function each time frame. The formation of feature vectors defining all acoustic speech units over well defined time frames can be used for purposes of speech coding, speech compression, speaker identification, language-of-speech identification, speech recognition, speech synthesis, speech translation, speech telephony, and speech teaching.

The effect of abstract versus concrete framing on judgments of biological and psychological bases of behavior.

PubMed

Kim, Nancy S; Johnson, Samuel G B; Ahn, Woo-Kyoung; Knobe, Joshua

2017-01-01

Human behavior is frequently described both in abstract, general terms and in concrete, specific terms. We asked whether these two ways of framing equivalent behaviors shift the inferences people make about the biological and psychological bases of those behaviors. In five experiments, we manipulated whether behaviors are presented concretely (i.e. with reference to a specific person, instantiated in the particular context of that person's life) or abstractly (i.e. with reference to a category of people or behaviors across generalized contexts). People judged concretely framed behaviors to be less biologically based and, on some dimensions, more psychologically based than the same behaviors framed in the abstract. These findings held true for both mental disorders (Experiments 1 and 2) and everyday behaviors (Experiments 4 and 5), and yielded downstream consequences for the perceived efficacy of disorder treatments (Experiment 3). Implications for science educators, students of science, and members of the lay public are discussed.

Frame Decoder for Consultative Committee for Space Data Systems (CCSDS)

NASA Technical Reports Server (NTRS)

Reyes, Miguel A. De Jesus

2014-01-01

GNU Radio is a free and open source development toolkit that provides signal processing to implement software radios. It can be used with low-cost external RF hardware to create software defined radios, or without hardware in a simulation-like environment. GNU Radio applications are primarily written in Python and C++. The Universal Software Radio Peripheral (USRP) is a computer-hosted software radio designed by Ettus Research. The USRP connects to a host computer via high-speed Gigabit Ethernet. Using the open source Universal Hardware Driver (UHD), we can run GNU Radio applications using the USRP. An SDR is a "radio in which some or all physical layer functions are software defined"(IEEE Definition). A radio is any kind of device that wirelessly transmits or receives radio frequency (RF) signals in the radio frequency. An SDR is a radio communication system where components that have been typically implemented in hardware are implemented in software. GNU Radio has a generic packet decoder block that is not optimized for CCSDS frames. Using this generic packet decoder will add bytes to the CCSDS frames and will not permit for bit error correction using Reed-Solomon. The CCSDS frames consist of 256 bytes, including a 32-bit sync marker (0x1ACFFC1D). This frames are generated by the Space Data Processor and GNU Radio will perform the modulation and framing operations, including frame synchronization.

Non-heuristic automatic techniques for overcoming low signal-to-noise-ratio bias of localization microscopy and multiple signal classification algorithm.

PubMed

Agarwal, Krishna; Macháň, Radek; Prasad, Dilip K

2018-03-21

Localization microscopy and multiple signal classification algorithm use temporal stack of image frames of sparse emissions from fluorophores to provide super-resolution images. Localization microscopy localizes emissions in each image independently and later collates the localizations in all the frames, giving same weight to each frame irrespective of its signal-to-noise ratio. This results in a bias towards frames with low signal-to-noise ratio and causes cluttered background in the super-resolved image. User-defined heuristic computational filters are employed to remove a set of localizations in an attempt to overcome this bias. Multiple signal classification performs eigen-decomposition of the entire stack, irrespective of the relative signal-to-noise ratios of the frames, and uses a threshold to classify eigenimages into signal and null subspaces. This results in under-representation of frames with low signal-to-noise ratio in the signal space and over-representation in the null space. Thus, multiple signal classification algorithms is biased against frames with low signal-to-noise ratio resulting into suppression of the corresponding fluorophores. This paper presents techniques to automatically debias localization microscopy and multiple signal classification algorithm of these biases without compromising their resolution and without employing heuristics, user-defined criteria. The effect of debiasing is demonstrated through five datasets of invitro and fixed cell samples.

Frequent frames as a cue for grammatical categories in child directed speech.

PubMed

Mintz, Toben H

2003-11-01

This paper introduces the notion of frequent frames, distributional patterns based on co-occurrence patterns of words in sentences, then investigates the usefulness of this information in grammatical categorization. A frame is defined as two jointly occurring words with one word intervening. Qualitative and quantitative results from distributional analyses of six different corpora of child directed speech are presented in two experiments. In the analyses, words that were surrounded by the same frequent frame were categorized together. The results show that frequent frames yield very accurate categories. Furthermore, evidence from behavioral studies suggests that infants and adults are sensitive to frame-like units, and that adults use them to categorize words. This evidence, along with the success of frames in categorizing words, provides support for frames as a basis for the acquisition of grammatical categories.

2-tier in-plane motion correction and out-of-plane motion filtering for contrast-enhanced ultrasound.

PubMed

Ta, Casey N; Eghtedari, Mohammad; Mattrey, Robert F; Kono, Yuko; Kummel, Andrew C

2014-11-01

Contrast-enhanced ultrasound (CEUS) cines of focal liver lesions (FLLs) can be quantitatively analyzed to measure tumor perfusion on a pixel-by-pixel basis for diagnostic indication. However, CEUS cines acquired freehand and during free breathing cause nonuniform in-plane and out-of-plane motion from frame to frame. These motions create fluctuations in the time-intensity curves (TICs), reducing the accuracy of quantitative measurements. Out-of-plane motion cannot be corrected by image registration in 2-dimensional CEUS and degrades the quality of in-plane motion correction (IPMC). A 2-tier IPMC strategy and adaptive out-of-plane motion filter (OPMF) are proposed to provide a stable correction of nonuniform motion to reduce the impact of motion on quantitative analyses. A total of 22 cines of FLLs were imaged with dual B-mode and contrast specific imaging to acquire a 3-minute TIC. B-mode images were analyzed for motion, and the motion correction was applied to both B-mode and contrast images. For IPMC, the main reference frame was automatically selected for each cine, and subreference frames were selected in each respiratory cycle and sequentially registered toward the main reference frame. All other frames were sequentially registered toward the local subreference frame. Four OPMFs were developed and tested: subsample normalized correlation (NC), subsample sum of absolute differences, mean frame NC, and histogram. The frames that were most dissimilar to the OPMF reference frame using 1 of the 4 above criteria in each respiratory cycle were adaptively removed by thresholding against the low-pass filter of the similarity curve. Out-of-plane motion filter was quantitatively evaluated by an out-of-plane motion metric (OPMM) that measured normalized variance in the high-pass filtered TIC within the tumor region-of-interest with low OPMM being the goal. Results for IPMC and OPMF were qualitatively evaluated by 2 blinded observers who ranked the motion in the cines before and after various combinations of motion correction steps. Quantitative measurements showed that 2-tier IPMC and OPMF improved imaging stability. With IPMC, the NC B-mode metric increased from 0.504 ± 0.149 to 0.585 ± 0.145 over all cines (P < 0.001). Two-tier IPMC also produced better fits on the contrast-specific TIC than industry standard IPMC techniques did (P < 0.02). In-plane motion correction and OPMF were shown to improve goodness of fit for pixel-by-pixel analysis (P < 0.001). Out-of-plane motion filter reduced variance in the contrast-specific signal as shown by a median decrease of 49.8% in the OPMM. Two-tier IPMC and OPMF were also shown to qualitatively reduce motion. Observers consistently ranked cines with IPMC higher than the same cine before IPMC (P < 0.001) as well as ranked cines with OPMF higher than when they were uncorrected. The 2-tier sequential IPMC and adaptive OPMF significantly reduced motion in 3-minute CEUS cines of FLLs, thereby overcoming the challenges of drift and irregular breathing motion in long cines. The 2-tier IPMC strategy provided stable motion correction tolerant of out-of-plane motion throughout the cine by sequentially registering subreference frames that bypassed the motion cycles, thereby overcoming the lack of a nearly stationary reference point in long cines. Out-of-plane motion filter reduced apparent motion by adaptively removing frames imaged off-plane from the automatically selected OPMF reference frame, thereby tolerating nonuniform breathing motion. Selection of the best OPMF by minimizing OPMM effectively reduced motion under a wide variety of motion patterns applicable to clinical CEUS. These semiautomated processes only required user input for region-of-interest selection and can improve the accuracy of quantitative perfusion measurements.

Speckle interferometry of Hipparcos link stars. III

NASA Technical Reports Server (NTRS)

White, Graeme L.; Jauncey, David L.; Reynolds, John E.; Blackmore, David R.; Matcher, Steven J.

1991-01-01

A third list of stars is presented which have been tested by speckle interferometry for use in the Hubble Space Telescope link between the Hipparcos astrometric reference frame and the extragalactic VLBI reference frame. Structural information on angular scales of 0.15-1.2 arcsec for 34 Southern Hemisphere stars is reported from observations made with the Imperial College Speckle Interferometer mounted on the Mount Stromlo 1.9-m telescope. Twenty-four percent of the stars (8 out of the 34) show evidence of multiplicity, in agreement with previous observations in this program.

JPL VLBI Analysis Center Report for 2012

NASA Technical Reports Server (NTRS)

Jacobs, Chris

2013-01-01

This report describes the activities of the JPL VLBI Analysis Center for the year 2012. The highlight of the year was the successful MSL rover Mars landing, which was supported by VLBI-based navigation using our combined spacecraft, celestial reference frame, terrestrial reference frame, earth orientation, and planetary ephemeris VLBI systems. We also supported several other missions with VLBI navigation measurements. A combined NASA-ESA network was demonstrated with first Ka-band fringes to ESA's Malargue, Argentina 35 m. We achieved first fringes with our new digital back end and Mark 5C recorders.

Technological Frame Incongruence, Diffusion, and Noncompliance

NASA Astrophysics Data System (ADS)

Sobreperez, Polly

The technological frames of reference strand of social shaping of technology theory is used to overlay the issues arising from a case study looking at noncompliance with information systems. A recent review of the theory suggests that although frame content is often addressed, frame structure, the process of framing, and the characteristics and outcomes of frames are largely overlooked. This paper attempts to address this shortfall by applying the indicators identified by case study research to the frames of different groups and using them to highlight differing perceptions and attitudes. In this way, the author suggests that issues surrounding noncompliance should not be dismissed as resistance but instead should be further studied by managers and developers, leading to accommodation of differing views. Further examination of frame incongruence reveals dependence on inefficient or ineffective organizational situations and thus these indicators can be useful in future studies to identify and address procedural, acceptance and cultural issues leading to acts of noncompliance.

Ground Contact Modeling for the Morpheus Test Vehicle Simulation

NASA Technical Reports Server (NTRS)

Cordova, Luis

2014-01-01

The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

Ground Contact Modeling for the Morpheus Test Vehicle Simulation

NASA Technical Reports Server (NTRS)

Cordova, Luis

2013-01-01

The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

LEOrbit: A program to calculate parameters relevant to modeling Low Earth Orbit spacecraft-plasma interaction

NASA Astrophysics Data System (ADS)

Marchand, R.; Purschke, D.; Samson, J.

2013-03-01

Understanding the physics of interaction between satellites and the space environment is essential in planning and exploiting space missions. Several computer models have been developed over the years to study this interaction. In all cases, simulations are carried out in the reference frame of the spacecraft and effects such as charging, the formation of electrostatic sheaths and wakes are calculated for given conditions of the space environment. In this paper we present a program used to compute magnetic fields and a number of space plasma and space environment parameters relevant to Low Earth Orbits (LEO) spacecraft-plasma interaction modeling. Magnetic fields are obtained from the International Geophysical Reference Field (IGRF) and plasma parameters are obtained from the International Reference Ionosphere (IRI) model. All parameters are computed in the spacecraft frame of reference as a function of its six Keplerian elements. They are presented in a format that can be used directly in most spacecraft-plasma interaction models. Catalogue identifier: AENY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 270308 No. of bytes in distributed program, including test data, etc.: 2323222 Distribution format: tar.gz Programming language: FORTRAN 90. Computer: Non specific. Operating system: Non specific. RAM: 7.1 MB Classification: 19, 4.14. External routines: IRI, IGRF (included in the package). Nature of problem: Compute magnetic field components, direction of the sun, sun visibility factor and approximate plasma parameters in the reference frame of a Low Earth Orbit satellite. Solution method: Orbit integration, calls to IGRF and IRI libraries and transformation of coordinates from geocentric to spacecraft frame reference. Restrictions: Low Earth orbits, altitudes between 150 and 2000 km. Running time: Approximately two seconds to parameterize a full orbit with 1000 points.

A FORTRAN version implementation of block adjustment of CCD frames and its preliminary application

NASA Astrophysics Data System (ADS)

Yu, Y.; Tang, Z.-H.; Li, J.-L.; Zhao, M.

2005-09-01

A FORTRAN version implementation of the block adjustment (BA) of overlapping CCD frames is developed and its flowchart is shown. The program is preliminarily applied to obtain the optical positions of four extragalactic radio sources. The results show that because of the increase in the number and sky coverage of reference stars the precision of optical positions with BA is improved compared with the single CCD frame adjustment.

Emergent Bilinguals: Framing Students as Statistical Data?

ERIC Educational Resources Information Center

Koyama, Jill; Menken, Kate

2013-01-01

Immigrant youth who are designated as English language learners in American schools--whom we refer to as "emergent bilinguals"--are increasingly framed by numerical calculations. Utilizing the notion of assemblage from actor-network theory (ANT), we trace how emergent bilinguals are discursively constructed by officials, administrators,…

VELOCITY FIELD OF COMPRESSIBLE MAGNETOHYDRODYNAMIC TURBULENCE: WAVELET DECOMPOSITION AND MODE SCALINGS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kowal, Grzegorz; Lazarian, A., E-mail: kowal@astro.wisc.ed, E-mail: lazarian@astro.wisc.ed

We study compressible magnetohydrodynamic turbulence, which holds the key to many astrophysical processes, including star formation and cosmic-ray propagation. To account for the variations of the magnetic field in the strongly turbulent fluid, we use wavelet decomposition of the turbulent velocity field into Alfven, slow, and fast modes, which presents an extension of the Cho and Lazarian decomposition approach based on Fourier transforms. The wavelets allow us to follow the variations of the local direction of the magnetic field and therefore improve the quality of the decomposition compared to the Fourier transforms, which are done in the mean field referencemore » frame. For each resulting component, we calculate the spectra and two-point statistics such as longitudinal and transverse structure functions as well as higher order intermittency statistics. In addition, we perform a Helmholtz- Hodge decomposition of the velocity field into incompressible and compressible parts and analyze these components. We find that the turbulence intermittency is different for different components, and we show that the intermittency statistics depend on whether the phenomenon was studied in the global reference frame related to the mean magnetic field or in the frame defined by the local magnetic field. The dependencies of the measures we obtained are different for different components of the velocity; for instance, we show that while the Alfven mode intermittency changes marginally with the Mach number, the intermittency of the fast mode is substantially affected by the change.« less

What visual information is used for stereoscopic depth displacement discrimination?

PubMed

Nefs, Harold T; Harris, Julie M

2010-01-01

There are two ways to detect a displacement in stereoscopic depth, namely by monitoring the change in disparity over time (CDOT) or by monitoring the interocular velocity difference (IOVD). Though previous studies have attempted to understand which cue is most significant for the visual system, none has designed stimuli that provide a comparison in terms of relative efficiency between them. Here we used two-frame motion and random-dot noise to deliver equivalent strengths of CDOT and IOVD information to the visual system. Using three kinds of random-dot stimuli, we were able to isolate CDOT or IOVD or deliver both simultaneously. The proportion of dots delivering CDOT or IOVD signals could be varied, and we defined the discrimination threshold as the proportion needed to detect the direction of displacement (towards or away). Thresholds were similar for stimuli containing CDOT only, and containing both CDOT and IOVD, but only one participant was able to consistently perceive the displacement for stimuli containing only IOVD. We also investigated the effect of disparity pedestals on discrimination. Performance was best when the displacement crossed the reference plane, but was not significantly different for stimuli containing CDOT only and those containing both CDOT and IOVD. When stimuli are specifically designed to provide equivalent two-frame motion or disparity-change, few participants can reliably detect displacement when IOVD is the only cue. This challenges the notion that IOVD is involved in the discrimination of direction of displacement in two-frame motion displays.

Reference Accuracy among Research Articles Published in "Research on Social Work Practice"

ERIC Educational Resources Information Center

Wilks, Scott E.; Geiger, Jennifer R.; Bates, Samantha M.; Wright, Amy L.

2017-01-01

Objective: The objective was to examine reference errors in research articles published in Research on Social Work Practice. High rates of reference errors in other top social work journals have been noted in previous studies. Methods: Via a sampling frame of 22,177 total references among 464 research articles published in the previous decade, a…

Cognitive Style, Creativity Framing and Effects

ERIC Educational Resources Information Center

Dew, Robert

2009-01-01

This study investigates how individuals with different cognitive styles respond to choices involving framing effects. The results suggest that cognitive style as defined by Kirton (1976) is far more complex than previous studies indicate. Kirton characterises "Innovators" as rule breakers and "Adaptors" as conformists. The most…

Visuospatial memory computations during whole-body rotations in roll.

PubMed

Van Pelt, S; Van Gisbergen, J A M; Medendorp, W P

2005-08-01

We used a memory-saccade task to test whether the location of a target, briefly presented before a whole-body rotation in roll, is stored in egocentric or in allocentric coordinates. To make this distinction, we exploited the fact that subjects, when tilted sideways in darkness, make systematic errors when indicating the direction of gravity (an allocentric task) even though they have a veridical percept of their self-orientation in space. We hypothesized that if spatial memory is coded allocentrically, these distortions affect the coding of remembered targets and their readout after a body rotation. Alternatively, if coding is egocentric, updating for body rotation becomes essential and errors in performance should be related to the amount of intervening rotation. Subjects (n = 6) were tested making saccades to remembered world-fixed targets after passive body tilts. Initial and final tilt angle ranged between -120 degrees CCW and 120 degrees CW. The results showed that subjects made large systematic directional errors in their saccades (up to 90 degrees ). These errors did not occur in the absence of intervening body rotation, ruling out a memory degradation effect. Regression analysis showed that the errors were closely related to the amount of subjective allocentric distortion at both the initial and final tilt angle, rather than to the amount of intervening rotation. We conclude that the brain uses an allocentric reference frame, possibly gravity-based, to code visuospatial memories during whole-body tilts. This supports the notion that the brain can define information in multiple frames of reference, depending on sensory inputs and task demands.

Processing techniques for software based SAR processors

NASA Technical Reports Server (NTRS)

Leung, K.; Wu, C.

1983-01-01

Software SAR processing techniques defined to treat Shuttle Imaging Radar-B (SIR-B) data are reviewed. The algorithms are devised for the data processing procedure selection, SAR correlation function implementation, multiple array processors utilization, cornerturning, variable reference length azimuth processing, and range migration handling. The Interim Digital Processor (IDP) originally implemented for handling Seasat SAR data has been adapted for the SIR-B, and offers a resolution of 100 km using a processing procedure based on the Fast Fourier Transformation fast correlation approach. Peculiarities of the Seasat SAR data processing requirements are reviewed, along with modifications introduced for the SIR-B. An Advanced Digital SAR Processor (ADSP) is under development for use with the SIR-B in the 1986 time frame as an upgrade for the IDP, which will be in service in 1984-5.

Witchcraft illness in the Evuzok nosological system.

PubMed

Guimera, L M

1978-12-01

The Evuzok nosological system is structured with respect to two frames of reference, one designating illness as an empirical reality (descriptive subsystem), the other designating it according to its religious, magical and social significance (etiological subsystem). The articulation of these two subsystems is brought about in the process of diagnosis. Having examined this system as a whole, the author devotes his attention to a particular set of etiological categories, those which associate illness with witchcraft (nocturnal illnesses). He attempts to define their distinctive traits and, from this, to determine their common elemental structure. This study, based on a number of years of fieldwork, is part of an ongoing research program on African folk-medicine pursued by the Laboratoire d'Ethnologie et de Sociologie Comparative of the Université de Paris X.

The Virtual Reference Librarian's Handbook.

ERIC Educational Resources Information Center

Lipow, Anne Grodzins

This book is a practical guide to librarians and their administrators who are thinking about or in the early stages of providing virtual reference service. Part 1, "The Decision to Go Virtual," provides a context for thinking about virtual reference, including the benefits and problems, getting in the virtual frame of mind, and shopping…

Adaptive Control Of Remote Manipulator

NASA Technical Reports Server (NTRS)

Seraji, Homayoun

1989-01-01

Robotic control system causes remote manipulator to follow closely reference trajectory in Cartesian reference frame in work space, without resort to computationally intensive mathematical model of robot dynamics and without knowledge of robot and load parameters. System, derived from linear multivariable theory, uses relatively simple feedforward and feedback controllers with model-reference adaptive control.

Brain potentials associated with the outcome processing in framing effects.

PubMed

Ma, Qingguo; Feng, Yandong; Xu, Qing; Bian, Jun; Tang, Huixian

2012-10-24

Framing effect is a cognitive bias referring to the phenomenon that people respond differently to different but objectively equivalent descriptions of the same problem. By measuring event-related potentials, the present study aimed to investigate the neural mechanisms underlying the framing effect, especially how the negative and positive frames influence the outcome processing in our brain. Participants were presented directly with outcomes framed either positively in terms of lives saved or negatively in terms of lives lost in large and small group conditions, and were asked to rate the favorableness of each of them. The behavioral results showed that the framing effect occurred in both group size conditions, with more favorable evaluations associated with positive framing. Compared with outcomes in positive framing condition, a significant feedback-related negativity (FRN) effect was elicited by outcomes in negative framing condition, even though the outcomes in different conditions were objectively equivalent. The results are explained in terms of the associative model of attribute framing effect which states that attribute framing effect occurs as a result of a valence-based associative processing. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

"The Academic Game" as a Frame Game.

ERIC Educational Resources Information Center

Bredemeier, Mary E.; And Others

1981-01-01

Describes a frame game which focuses on problems of sex, status, and organizational development. "The Academic Game" is a specific model of a generic game that has differential consequences for men and women, and is easily adaptable to other organizational settings, including public administration and industry. Six references are listed.…

ostglacial rebound from VLBI Geodesy: On Establishing Vertical Reference

NASA Technical Reports Server (NTRS)

Argus, Donald .

1996-01-01

I propose that a useful reference frame for vertical motions is that found by minimizing differences between vertical motions observed with VLBI [Ma and Ryan, 1995] and predictions from postglacial rebound predictions [Peltier, 1995].

Photovoltaic assemblies and methods for transporting

DOEpatents

Almy, Charles; Campbell, Matt; Sandler, Reuben; Wares, Brian; Wayman, Elizabeth

2014-08-05

A PV assembly including framework, PV laminate(s), and a stiffening device. The framework includes a perimeter frame at least 10 feet in length and at least 5 feet in width. The PV laminate(s) are assembled to the perimeter frame to define a receiving zone having a depth of not more than 8 inches. The stiffening device is associated with the framework and is configured to provide a first state and a second state. In the first state, an entirety of the stiffening device is maintained within the receiving zone. In the second state, at least a portion of the stiffening device projects from the receiving zone. The stiffening device enhances a stiffness of the PV assembly in a plane of the perimeter frame, and can include rods defining truss structures.

Speech coding, reconstruction and recognition using acoustics and electromagnetic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holzrichter, J.F.; Ng, L.C.

The use of EM radiation in conjunction with simultaneously recorded acoustic speech information enables a complete mathematical coding of acoustic speech. The methods include the forming of a feature vector for each pitch period of voiced speech and the forming of feature vectors for each time frame of unvoiced, as well as for combined voiced and unvoiced speech. The methods include how to deconvolve the speech excitation function from the acoustic speech output to describe the transfer function each time frame. The formation of feature vectors defining all acoustic speech units over well defined time frames can be used formore » purposes of speech coding, speech compression, speaker identification, language-of-speech identification, speech recognition, speech synthesis, speech translation, speech telephony, and speech teaching. 35 figs.« less

Photovoltaic assemblies and methods for transporting

DOEpatents

Almy, Charles; Campbell, Matt; Sandler, Reuben; Wares, Brian; Wayman, Elizabeth

2013-09-17

A PV assembly including framework, PV laminate(s), and a stiffening device. The framework includes a perimeter frame at least 10 feet in length and at least 5 feet in width. The PV laminate(s) are assembled to the perimeter frame to define a receiving zone having a depth of not more than 8 inches. The stiffening device is associated with the framework and is configured to provide a first state and a second state. In the first state, an entirety of the stiffening device is maintained within the receiving zone. In the second state, at least a portion of the stiffening device projects from the receiving zone. The stiffening device enhances a stiffness of the PV assembly in a plane of the perimeter frame, and can include rods defining truss structures.

Non-linearity of geocentre motion and its impact on the origin of the terrestrial reference frame

NASA Astrophysics Data System (ADS)

Dong, Danan; Qu, Weijing; Fang, Peng; Peng, Dongju

2014-08-01

The terrestrial reference frame is a cornerstone for modern geodesy and its applications for a wide range of Earth sciences. The underlying assumption for establishing a terrestrial reference frame is that the motion of the solid Earth's figure centre relative to the mass centre of the Earth system on a multidecadal timescale is linear. However, past international terrestrial reference frames (ITRFs) showed unexpected accelerated motion in their translation parameters. Based on this underlying assumption, the inconsistency of relative origin motions of the ITRFs has been attributed to data reduction imperfection. We investigated the impact of surface mass loading from atmosphere, ocean, snow, soil moisture, ice sheet, glacier and sea level from 1983 to 2008 on the geocentre variations. The resultant geocentre time-series display notable trend acceleration from 1998 onward, in particular in the z-component. This effect is primarily driven by the hydrological mass redistribution in the continents (soil moisture, snow, ice sheet and glacier). The acceleration is statistically significant at the 99 per cent confidence level as determined using the Mann-Kendall test, and it is highly correlated with the satellite laser ranging determined translation series. Our study, based on independent geophysical and hydrological models, demonstrates that, in addition to systematic errors from analysis procedures, the observed non-linearity of the Earth-system behaviour at interannual timescales is physically driven and is able to explain 42 per cent of the disparity between the origins of ITRF2000 and ITRF2005, as well as the high level of consistency between the ITRF2005 and ITRF2008 origins.

OPTICAL SPECTRA OF CANDIDATE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) FLAT-SPECTRUM RADIO SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Stanford, Laura M.; Johnston, Helen M.

2013-07-01

Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame.more » We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.« less

A discourse analysis of the construction of mental illness in two UK newspapers from 1985-2000.

PubMed

Paterson, Brodie

2007-10-01

This study explored the discourse of mental illness contained within two UK newspapers over a 15-year period, excluding those stories that mentioned any reference to a diagnosis. Using frame analysis, a form of discourse analysis, ten distinct frames were identified and classified into "stories." These ten stories were categorized as: foreign, legal, drug, feature, trauma, tragedy, community care tragedy, social policy, inquiry report, and sports/celebrity stories. Each frame is described and the potential influence of such frames on both social policy and nursing practice is discussed.

External skeletal robusticity of children and adolescents - European references from birth to adulthood and international comparisons.

PubMed

Mumm, Rebekka; Godina, Elena; Koziel, Slawomir; Musalek, Martin; Sedlak, Petr; Wittwer-Backofen, Ursula; Hesse, Volker; Dasgupta, Parasmani; Henneberg, Maciej; Scheffler, Christiane

2018-06-11

Background: In our modern world, the way of life in nutritional and activity behaviour has changed. As a consequence, parallel trends of an epidemic of overweight and a decline in external skeletal robusticity are observed in children and adolescents. Aim: We aim to develop reference centiles for external skeletal robusticity of European girls and boys aged 0 to 18 years using the Frame Index as an indicator and identify population specific age-related patterns. Methods: We analysed cross-sectional & longitudinal data on body height and elbow breadth of boys and girls from Europe (0-18 years, n = 41.679), India (7-18 years, n = 3.297) and South Africa (3-18 years, n = 4.346). As an indicator of external skeletal robusticity Frame Index after Frisancho (1990) was used. We developed centiles for boys and girls using the LMS-method and its extension. Results: Boys have greater external skeletal robusticity than girls. Whereas in girls Frame Index decreases continuously during growth, an increase of Frame Index from 12 to 16 years in European boys can be observed. Indian and South African boys are almost similar in Frame Index to European boys. In girls, the pattern is slightly different. Whereas South African girls are similar to European girls, Indian girls show a lesser external skeletal robusticity. Conclusion: Accurate references for external skeletal robusticity are needed to evaluate if skeletal development is adequate per age. They should be used to monitor effects of changes in way of life and physical activity levels in children and adolescents to avoid negative health outcomes like osteoporosis and arthrosis.

Dragging of inertial frames.

PubMed

Ciufolini, Ignazio

2007-09-06

The origin of inertia has intrigued scientists and philosophers for centuries. Inertial frames of reference permeate our daily life. The inertial and centrifugal forces, such as the pull and push that we feel when our vehicle accelerates, brakes and turns, arise because of changes in velocity relative to uniformly moving inertial frames. A classical interpretation ascribed these forces to acceleration relative to some absolute frame independent of the cosmological matter, whereas an opposite view related them to acceleration relative to all the masses and 'fixed stars' in the Universe. An echo and partial realization of the latter idea can be found in Einstein's general theory of relativity, which predicts that a spinning mass will 'drag' inertial frames along with it. Here I review the recent measurements of frame dragging using satellites orbiting Earth.

A brief note on Weyl frames and canonical transformations in geometrical scalar–tensor theories of gravity

NASA Astrophysics Data System (ADS)

Barreto, A. B.; Pucheu, M. L.; Romero, C.

2018-02-01

We consider scalar–tensor theories of gravity defined in Weyl integrable space-time and show that for time-lapse extended Robertson–Walker metrics in the ADM formalism a class of Weyl transformations corresponding to change of frames induce canonical transformations between different representations of the phase space. In this context, we discuss the physical equivalence of two distinct Weyl frames at the classical level.

Work and Inertial Frames

NASA Astrophysics Data System (ADS)

Kaufman, Richard

2017-12-01

A fairly recent paper resolves a large discrepancy in the internal energy utilized to fire a cannon as calculated by two inertial observers. Earth and its small reaction velocity must be considered in the system so that the change in kinetic energy is calculated correctly. This paper uses a car in a similar scenario, but considers the work done by forces acting over distances. An analysis of the system must include all energy interactions, including the work done on the car and especially the (negative) work done on Earth in a moving reference frame. This shows the importance of considering the force on Earth and the distance Earth travels. For calculation of work in inertial reference frames, the center of mass perspective is shown to be useful. We also consider the energy requirements to efficiently accelerate a mass among interacting masses.

Frequency analysis of a two-stage planetary gearbox using two different methodologies

NASA Astrophysics Data System (ADS)

Feki, Nabih; Karray, Maha; Khabou, Mohamed Tawfik; Chaari, Fakher; Haddar, Mohamed

2017-12-01

This paper is focused on the characterization of the frequency content of vibration signals issued from a two-stage planetary gearbox. To achieve this goal, two different methodologies are adopted: the lumped-parameter modeling approach and the phenomenological modeling approach. The two methodologies aim to describe the complex vibrations generated by a two-stage planetary gearbox. The phenomenological model describes directly the vibrations as measured by a sensor fixed outside the fixed ring gear with respect to an inertial reference frame, while results from a lumped-parameter model are referenced with respect to a rotating frame and then transferred into an inertial reference frame. Two different case studies of the two-stage planetary gear are adopted to describe the vibration and the corresponding spectra using both models. Each case presents a specific geometry and a specific spectral structure.

Assessment of the accuracy of global geodetic satellite laser ranging observations and estimated impact on ITRF scale: estimation of systematic errors in LAGEOS observations 1993-2014

NASA Astrophysics Data System (ADS)

Appleby, Graham; Rodríguez, José; Altamimi, Zuheir

2016-12-01

Satellite laser ranging (SLR) to the geodetic satellites LAGEOS and LAGEOS-2 uniquely determines the origin of the terrestrial reference frame and, jointly with very long baseline interferometry, its scale. Given such a fundamental role in satellite geodesy, it is crucial that any systematic errors in either technique are at an absolute minimum as efforts continue to realise the reference frame at millimetre levels of accuracy to meet the present and future science requirements. Here, we examine the intrinsic accuracy of SLR measurements made by tracking stations of the International Laser Ranging Service using normal point observations of the two LAGEOS satellites in the period 1993 to 2014. The approach we investigate in this paper is to compute weekly reference frame solutions solving for satellite initial state vectors, station coordinates and daily Earth orientation parameters, estimating along with these weekly average range errors for each and every one of the observing stations. Potential issues in any of the large number of SLR stations assumed to have been free of error in previous realisations of the ITRF may have been absorbed in the reference frame, primarily in station height. Likewise, systematic range errors estimated against a fixed frame that may itself suffer from accuracy issues will absorb network-wide problems into station-specific results. Our results suggest that in the past two decades, the scale of the ITRF derived from the SLR technique has been close to 0.7 ppb too small, due to systematic errors either or both in the range measurements and their treatment. We discuss these results in the context of preparations for ITRF2014 and additionally consider the impact of this work on the currently adopted value of the geocentric gravitational constant, GM.