Science.gov

Sample records for absolute positioning accuracy

  1. Achieving Climate Change Absolute Accuracy in Orbit

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  2. Individual Differences in Absolute and Relative Metacomprehension Accuracy

    ERIC Educational Resources Information Center

    Maki, Ruth H.; Shields, Micheal; Wheeler, Amanda Easton; Zacchilli, Tammy Lowery

    2005-01-01

    The authors investigated absolute and relative metacomprehension accuracy as a function of verbal ability in college students. Students read hard texts, revised texts, or a mixed set of texts. They then predicted their performance, took a multiple-choice test on the texts, and made posttest judgments about their performance. With hard texts,…

  3. Simultaneously improving the sensitivity and absolute accuracy of CPT magnetometer.

    PubMed

    Liang, Shang-Qing; Yang, Guo-Qing; Xu, Yun-Fei; Lin, Qiang; Liu, Zhi-Heng; Chen, Zheng-Xiang

    2014-03-24

    A new method to improve the sensitivity and absolute accuracy simultaneously for coherent population trapping (CPT) magnetometer based on the differential detection method is presented. Two modulated optical beams with orthogonal circular polarizations are applied, in one of which two magnetic resonances are excited simultaneously by modulating a 3.4GHz microwave with Larmor frequency. When a microwave frequency shift is introduced, the difference in the power transmitted through the cell in each beam shows a low noise resonance. The sensitivity of 2pT/Hz @ 10Hz is achieved. Meanwhile, the absolute accuracy of ± 0.5nT within the magnetic field ranging from 20000nT to 100000nT is realized.

  4. Alaska national hydrography dataset positional accuracy assessment study

    USGS Publications Warehouse

    Arundel, Samantha; Yamamoto, Kristina H.; Constance, Eric; Mantey, Kim; Vinyard-Houx, Jeremy

    2013-01-01

    Initial visual assessments Wide range in the quality of fit between features in NHD and these new image sources. No statistical analysis has been performed to actually quantify accuracy Determining absolute accuracy is cost prohibitive (must collect independent, well defined test points) Quantitative analysis of relative positional error is feasible.

  5. Constraint on Absolute Accuracy of Metacomprehension Assessments: The Anchoring and Adjustment Model vs. the Standards Model

    ERIC Educational Resources Information Center

    Kwon, Heekyung

    2011-01-01

    The objective of this study is to provide a systematic account of three typical phenomena surrounding absolute accuracy of metacomprehension assessments: (1) the absolute accuracy of predictions is typically quite low; (2) there exist individual differences in absolute accuracy of predictions as a function of reading skill; and (3) postdictions…

  6. Absolute positioning using DORIS tracking of the SPOT-2 satellite

    NASA Technical Reports Server (NTRS)

    Watkins, M. M.; Ries, J. C.; Davis, G. W.

    1992-01-01

    The ability of the French DORIS system operating on the SPOT-2 satellite to provide absolute site positioning at the 20-30-centimeter level using 80 d of data is demonstrated. The accuracy of the vertical component is comparable to that of the horizontal components, indicating that residual troposphere error is not a limiting factor. The translation parameters indicate that the DORIS network realizes a geocentric frame to about 50 nm in each component. The considerable amount of data provided by the nearly global, all-weather DORIS network allowed this complex parameterization required to reduce the unmodeled forces acting on the low-earth satellite. Site velocities with accuracies better than 10 mm/yr should certainly be possible using the multiyear span of the SPOT series and Topex/Poseidon missions.

  7. Absolute vs. relative error characterization of electromagnetic tracking accuracy

    NASA Astrophysics Data System (ADS)

    Matinfar, Mohammad; Narayanasamy, Ganesh; Gutierrez, Luis; Chan, Raymond; Jain, Ameet

    2010-02-01

    Electromagnetic (EM) tracking systems are often used for real time navigation of medical tools in an Image Guided Therapy (IGT) system. They are specifically advantageous when the medical device requires tracking within the body of a patient where line of sight constraints prevent the use of conventional optical tracking. EM tracking systems are however very sensitive to electromagnetic field distortions. These distortions, arising from changes in the electromagnetic environment due to the presence of conductive ferromagnetic surgical tools or other medical equipment, limit the accuracy of EM tracking, in some cases potentially rendering tracking data unusable. We present a mapping method for the operating region over which EM tracking sensors are used, allowing for characterization of measurement errors, in turn providing physicians with visual feedback about measurement confidence or reliability of localization estimates. In this instance, we employ a calibration phantom to assess distortion within the operating field of the EM tracker and to display in real time the distribution of measurement errors, as well as the location and extent of the field associated with minimal spatial distortion. The accuracy is assessed relative to successive measurements. Error is computed for a reference point and consecutive measurement errors are displayed relative to the reference in order to characterize the accuracy in near-real-time. In an initial set-up phase, the phantom geometry is calibrated by registering the data from a multitude of EM sensors in a non-ferromagnetic ("clean") EM environment. The registration results in the locations of sensors with respect to each other and defines the geometry of the sensors in the phantom. In a measurement phase, the position and orientation data from all sensors are compared with the known geometry of the sensor spacing, and localization errors (displacement and orientation) are computed. Based on error thresholds provided by the

  8. Absolute Position Encoders With Vertical Image Binning

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.

    2005-01-01

    Improved optoelectronic patternrecognition encoders that measure rotary and linear 1-dimensional positions at conversion rates (numbers of readings per unit time) exceeding 20 kHz have been invented. Heretofore, optoelectronic pattern-recognition absoluteposition encoders have been limited to conversion rates <15 Hz -- too low for emerging industrial applications in which conversion rates ranging from 1 kHz to as much as 100 kHz are required. The high conversion rates of the improved encoders are made possible, in part, by use of vertically compressible or binnable (as described below) scale patterns in combination with modified readout sequences of the image sensors [charge-coupled devices (CCDs)] used to read the scale patterns. The modified readout sequences and the processing of the images thus read out are amenable to implementation by use of modern, high-speed, ultra-compact microprocessors and digital signal processors or field-programmable gate arrays. This combination of improvements makes it possible to greatly increase conversion rates through substantial reductions in all three components of conversion time: exposure time, image-readout time, and image-processing time.

  9. High accuracy absolute laser powermeter calibrated over the whole range

    SciTech Connect

    Miron, N.; Korony, G.; Velculescu, V.G.

    1994-12-31

    The main contribution to this laser powermeter is the capability of its detector to be electrically calibrated over the whole measuring range (0 ... 100W), with an accuracy better than 1%. This allows an improved accuracy in determining the second-order polynomial coefficients describing thermocouple electric response.

  10. System and method for calibrating a rotary absolute position sensor

    NASA Technical Reports Server (NTRS)

    Davis, Donald R. (Inventor); Permenter, Frank Noble (Inventor); Radford, Nicolaus A (Inventor)

    2012-01-01

    A system includes a rotary device, a rotary absolute position (RAP) sensor generating encoded pairs of voltage signals describing positional data of the rotary device, a host machine, and an algorithm. The algorithm calculates calibration parameters usable to determine an absolute position of the rotary device using the encoded pairs, and is adapted for linearly-mapping an ellipse defined by the encoded pairs to thereby calculate the calibration parameters. A method of calibrating the RAP sensor includes measuring the rotary position as encoded pairs of voltage signals, linearly-mapping an ellipse defined by the encoded pairs to thereby calculate the calibration parameters, and calculating an absolute position of the rotary device using the calibration parameters. The calibration parameters include a positive definite matrix (A) and a center point (q) of the ellipse. The voltage signals may include an encoded sine and cosine of a rotary angle of the rotary device.

  11. MSTAR: an absolute metrology sensor with sub-micron accuracy for space-based applications

    NASA Technical Reports Server (NTRS)

    Peters, Robert D.; Lay, Oliver P.; Dubovitsky, Serge; Burger, Johan P.; Jeganathan, Muthu

    2004-01-01

    The MSTAR sensor is a new system for measuring absolute distance, capable of resolving the integer cycle ambiguity of standard interferometers, and making it possible to measure distance with subnanometer accuracy.

  12. Confidence-Accuracy Calibration in Absolute and Relative Face Recognition Judgments

    ERIC Educational Resources Information Center

    Weber, Nathan; Brewer, Neil

    2004-01-01

    Confidence-accuracy (CA) calibration was examined for absolute and relative face recognition judgments as well as for recognition judgments from groups of stimuli presented simultaneously or sequentially (i.e., simultaneous or sequential mini-lineups). When the effect of difficulty was controlled, absolute and relative judgments produced…

  13. Piezoresistive position microsensors with ppm-accuracy

    NASA Astrophysics Data System (ADS)

    Stavrov, Vladimir; Shulev, Assen; Stavreva, Galina; Todorov, Vencislav

    2015-05-01

    In this article, the relation between position accuracy and the number of simultaneously measured values, such as coordinates, has been analyzed. Based on this, a conceptual layout of MEMS devices (microsensors) for multidimensional position monitoring comprising a single anchored and a single actuated part has been developed. Both parts are connected with a plurality of micromechanical flexures, and each flexure includes position detecting cantilevers. Microsensors having detecting cantilevers oriented in X and Y direction have been designed and prototyped. Experimentally measured results at characterization of 1D, 2D and 3D position microsensors are reported as well. Exploiting different flexure layouts, a travel range between 50μm and 1.8mm and sensors' sensitivity in the range between 30μV/μm and 5mV/μm@ 1V DC supply voltage have been demonstrated. A method for accurate calculation of all three Cartesian coordinates, based on measurement of at least three microsensors' signals has also been described. The analyses of experimental results prove the capability of position monitoring with ppm-(part per million) accuracy. The technology for fabrication of MEMS devices with sidewall embedded piezoresistors removes restrictions in strong improvement of their usability for position sensing with a high accuracy. The present study is, also a part of a common strategy for developing a novel MEMS-based platform for simultaneous accurate measurement of various physical values when they are transduced to a change of position.

  14. Positional Accuracy Assessment of Googleearth in Riyadh

    NASA Astrophysics Data System (ADS)

    Farah, Ashraf; Algarni, Dafer

    2014-06-01

    Google Earth is a virtual globe, map and geographical information program that is controlled by Google corporation. It maps the Earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS 3D globe. With millions of users all around the globe, GoogleEarth® has become the ultimate source of spatial data and information for private and public decision-support systems besides many types and forms of social interactions. Many users mostly in developing countries are also using it for surveying applications, the matter that raises questions about the positional accuracy of the Google Earth program. This research presents a small-scale assessment study of the positional accuracy of GoogleEarth® Imagery in Riyadh; capital of Kingdom of Saudi Arabia (KSA). The results show that the RMSE of the GoogleEarth imagery is 2.18 m and 1.51 m for the horizontal and height coordinates respectively.

  15. Positioning accuracy of the neurotron 1000

    SciTech Connect

    Cox, R.S.; Murphy, M.J.

    1995-12-31

    The Neuotron 1000 is a novel treatment machine under development for frameless stereotaxic radiosurgery that consists of a compact X-band accelerator mounted on a robotic arm. The therapy beam is guided to the lesion by an imaging system, which included two diagnostic x-ray cameras that view the patient during treatment. Patient position and motion are measured by the imaging system and appropriate corrections are communicated in real time to the robotic arm for beam targeting and motion tracking. The three tests reported here measured the pointing accuracy of the therapy beam and the present capability of the imaging guidance system. The positioning and pointing test measured the ability of the robotic arm to direct the beam through a test isocenter from arbitrary arm positions. The test isocenter was marked by a small light-sensitive crystal and the beam axis was simulated by a laser.

  16. Accuracy of the LPM tracking system considering dynamic position changes.

    PubMed

    Ogris, Georg; Leser, Roland; Horsak, Brian; Kornfeind, Philipp; Heller, Mario; Baca, Arnold

    2012-01-01

    This study investigates the accuracy of the tracking system LPM (local position measurement). The goal was to determine detailed error values of the system in the context of sports performance analyses. Six moderately trained male soccer players (amateur level) performed 276 runs on three different courses at six different speeds. Additionally, ten small-sided game plays were carried out. All runs and game plays were recorded with the LPM tracking system and the motion capture system VICON simultaneously. VICON served as the reference system. The absolute error of all LPM position estimations was on average 23.4±20.7 cm. The estimation for average velocities varied between 0.01 km h(-1) and 0.23 km h(-1), the maximum speed estimations differed by up to 2.71 km h(-1). In addition, the results showed that the accuracy of the LPM system is highly dependent on the instantaneous dynamics of the player and decreases in the margins of the observation field. These dependencies were quantified. Considering commonly used applications of position tracking systems in sports (Leser, Ogris, & Baca, 2011), the accuracy of LPM is acceptable for position and velocity estimations. The system provides valuable results for average velocities but seems to be far less reliable when dealing with high dynamic movements and measuring instantaneous velocities.

  17. Positional Accuracy of Gps Satellite Almanac

    NASA Astrophysics Data System (ADS)

    Ma, Lihua; Zhou, Shangli

    2014-12-01

    How to accelerate signal acquisition and shorten starting time are key problems in the Global Positioning System (GPS). GPS satellite almanac plays an important role in signal reception period. Almanac accuracy directly affects the speed of GPS signal acquisition, the start time of the receiver, and even the system performance to some extent. Combined with precise ephemeris products released by the International GNSS Service (IGS), the authors analyse GPS satellite almanac from the first day to the third day in the 1805th GPS week (from August 11 to 13, 2014 in the Gregorian calendar). The results show that mean of position errors in three-dimensional coordinate system varies from about 1 kilometer to 3 kilometers, which can satisfy the needs of common users.

  18. Using AIRS and IASI Data to Evaluate Absolute Radiometric Accuracy and Stability for Climate Applications

    NASA Technical Reports Server (NTRS)

    Aumann, Hartmut H.; Pagano, Thomas S.

    2008-01-01

    The creation of multi-decadal data sets for climate research requires better than 100 mK absolute calibration accuracy for the full range of spectral temperatures encountered under global conditions. Validation that this accuracy is achieved by the operational hyperspectral sounders from polar orbit is facilitated by comparing data from two instruments. Extreme radiometric calibration stability is critical to allow a long time series of noisy, but presumably long-term accurate truth measurements to be used for the validation of absolute accuracy at the 100 mK level. We use the RTGSST in the tropical oceans as ground truth. The difference between the AIRS derived sst2616 and the RTGSST based on six years of data shows a systematic cold bias of about 250 mK, but better than 4 mK/year stability. The double difference between AIRS and the RTGSST and IASI and the RTGSST with less than one year of data already allows statements at the 100 mK absolute level. It shows a 60 mK difference between the AIRS and the IASI calibration at 2616 cm-(sup 1) and 300 K, with a statistically insignificant 20 mK shift in six months.

  19. Time and position accuracy using codeless GPS

    NASA Technical Reports Server (NTRS)

    Dunn, C. E.; Jefferson, D. C.; Lichten, S. M.; Thomas, J. B.; Vigue, Y.; Young, L. E.

    1994-01-01

    The Global Positioning System has allowed scientists and engineers to make measurements having accuracy far beyond the original 15 meter goal of the system. Using global networks of P-Code capable receivers and extensive post-processing, geodesists have achieved baseline precision of a few parts per billion, and clock offsets have been measured at the nanosecond level over intercontinental distances. A cloud hangs over this picture, however. The Department of Defense plans to encrypt the P-Code (called Anti-Spoofing, or AS) in the fall of 1993. After this event, geodetic and time measurements will have to be made using codeless GPS receivers. However, there appears to be a silver lining to the cloud. In response to the anticipated encryption of the P-Code, the geodetic and GPS receiver community has developed some remarkably effective means of coping with AS without classified information. We will discuss various codeless techniques currently available and the data noise resulting from each. We will review some geodetic results obtained using only codeless data, and discuss the implications for time measurements. Finally, we will present the status of GPS research at JPL in relation to codeless clock measurements.

  20. Absolute position total internal reflection microscopy with an optical tweezer

    PubMed Central

    Liu, Lulu; Woolf, Alexander; Rodriguez, Alejandro W.; Capasso, Federico

    2014-01-01

    A noninvasive, in situ calibration method for total internal reflection microscopy (TIRM) based on optical tweezing is presented, which greatly expands the capabilities of this technique. We show that by making only simple modifications to the basic TIRM sensing setup and procedure, a probe particle’s absolute position relative to a dielectric interface may be known with better than 10 nm precision out to a distance greater than 1 μm from the surface. This represents an approximate 10× improvement in error and 3× improvement in measurement range over conventional TIRM methods. The technique’s advantage is in the direct measurement of the probe particle’s scattering intensity vs. height profile in situ, rather than relying on assumptions, inexact system analogs, or detailed knowledge of system parameters for calibration. To demonstrate the improved versatility of the TIRM method in terms of tunability, precision, and range, we show our results for the hindered near-wall diffusion coefficient for a spherical dielectric particle. PMID:25512542

  1. High-accuracy discrete positioning device

    NASA Technical Reports Server (NTRS)

    Brooks, John J. (Inventor)

    1994-01-01

    An article (30) is controllably and precisely positioned at one of three discrete locations defined by a linkage. The positioning apparatus includes two independently driven cranks (34, 42), with a link (50) pivotably connected between the two cranks (34, 42). Another connector (44) is pivotably connected between one of the cranks (34 or 42) and the article (30) to be positioned. The cranks (34, 42) are rotationally adjusted so that the pivot points (52, 54) of the link (50) are collinear with the axes of rotation of the cranks (40, 48), thereby defining one of the three discrete locations. Additional cranks and links can be provided to define additional discrete locations.

  2. An ERP Investigation of Orthographic Priming with Relative-Position and Absolute-Position Primes

    PubMed Central

    Grainger, Jonathan; Holcomb, Phillip J.

    2009-01-01

    The present study used event-related potentials to examine the time-course of relative-position and absolute-position orthographic priming. Relative-position priming was examined using primes formed by a concatenated subset of the target word’s letters (e.g., cllet/COLLECT vs. dlema/COLLECT), and absolute-position priming was investigated using hyphenated versions of these primes (c-lle-t/COLLECT vs. d-lem-a/COLLECT). Both manipulations modulated the ERP waveform starting at around 100 ms post-target onset and extending into the N400 component. The first clear manifestation of priming was found in the N250 component, where hyphenated primes were found to have an earlier, more robust and more widely distributed effect than the concatenated primes. On the other hand, both prime types had similar effects on N400 amplitude. These results provide important information about the time-course of activation of location-specific and location-invariant (word-centered) orthographic representations during visual word recognition. PMID:19285966

  3. Absolute calibration accuracy of L4 TM and L5 TM sensor image pairs

    USGS Publications Warehouse

    Chander, G.; Micijevic, E.

    2006-01-01

    The Landsat suite of satellites has collected the longest continuous archive of multispectral data of any land-observing space program. From the Landsat program's inception in 1972 to the present, the Earth science user community has benefited from a historical record of remotely sensed data. However, little attention has been paid to ensuring that the data are calibrated and comparable from mission to mission, Launched in 1982 and 1984 respectively, the Landsat 4 (L4) and Landsat 5 (L5) Thematic Mappers (TM) are the backbone of an extensive archive of moderate resolution Earth imagery. To evaluate the "current" absolute accuracy of these two sensors, image pairs from the L5 TM and L4 TM sensors were compared. The approach involves comparing image statistics derived from large common areas observed eight days apart by the two sensors. The average percent differences in reflectance estimates obtained from the L4 TM agree with those from the L5 TM to within 15 percent. Additional work to characterize the absolute differences between the two sensors over the entire mission is in progress.

  4. Optical-fiber pyrometer positioning accuracy analysis

    NASA Astrophysics Data System (ADS)

    Tapetado, A.; García, E.; Díaz-Álvarez, J.; Miguélez, M. H.; Vazquez, C.

    2016-05-01

    The influence of the distance between the fiber end and the machined surface on temperature measurements in a two-color fiber-optic pyrometer is analyzed. The propose fiber-optic pyrometer is capable of measuring highly localized temperatures, while avoiding the use of lenses or fiber bundles, by using a standard graded index glass fiber OM1 with 62.5/125 core and cladding diameters. The fiber is placed very close to the target and below the tool insert. The output optical power at both wavelength bands is theoretically and experimentally analyzed for a temperature of 650°C at different fiber positions in a range of 2mm. The results show that there is no influence of the fiber position on the measured optical power and therefore, on the measured temperature.

  5. Estimating the absolute position of a mobile robot using position probability grids

    SciTech Connect

    Burgard, W.; Fox, D.; Hennig, D.; Schmidt, T.

    1996-12-31

    In order to re-use existing models of the environment mobile robots must be able to estimate their position and orientation in such models. Most of the existing methods for position estimation are based on special purpose sensors or aim at tracking the robot`s position relative to the known starting point. This paper describes the position probability grid approach to estimating the robot`s absolute position and orientation in a metric model of the environment. Our method is designed to work with standard sensors and is independent of any knowledge about the starting point. It is a Bayesian approach based on certainty grids. In each cell of such a grid we store the probability that this cell refers to the current position of the robot. These probabilities are obtained by integrating the likelihoods of sensor readings over time. Results described in this paper show that our technique is able to reliably estimate the position of a robot in complex environments. Our approach has proven to be robust with respect to inaccurate environmental models, noisy sensors, and ambiguous situations.

  6. Handheld Reflective Foil Emissometer with 0.007 Absolute Accuracy at 0.05

    NASA Astrophysics Data System (ADS)

    van der Ham, E. W. M.; Ballico, M. J.

    2014-07-01

    The development and performance of a handheld emissometer for the measurement of the emissivity of highly reflective metallic foils used for the insulation of domestic and commercial buildings are described. Reflective roofing insulation based on a thin coating of metal on a more robust substrate is very widely used in hotter climates to reduce the radiant heat transfer between the ceiling and roof in commercial and residential buildings. The required normal emissivity of these foils is generally below 0.05, so stray reflected ambient infrared radiation (IR) makes traditional reflectance-based measurements of emissivity very difficult to achieve with the required accuracy. Many manufacturers apply additional coatings onto the metallic foil to reduce visible glare during installation on a roof, and to provide protection to the thin reflective layer; however, this layer can also substantially increase the IR emissivity. The system as developed at the National Measurement Institute, Australia (NMIA) is based on the principle of measurement of the modulation in thermal infrared radiation, as the sample is thermally modulated by hot and cold air streams. A commercial infrared to band radiation thermometer with a highly specialized stray and reflected radiation shroud attachment is used as the detector system, allowing for convenient handheld field measurements. The performance and accuracy of the system have been compared with NMIA's reference emissometer systems for a number of typical material samples, demonstrating its capability to measure the absolute thermal emissivity of these very highly reflective foils with an uncertainty of better than.

  7. Absolute Position of Targets Measured Through a Chamber Window Using Lidar Metrology Systems

    NASA Technical Reports Server (NTRS)

    Kubalak, David; Hadjimichael, Theodore; Ohl, Raymond; Slotwinski, Anthony; Telfer, Randal; Hayden, Joseph

    2012-01-01

    Lidar is a useful tool for taking metrology measurements without the need for physical contact with the parts under test. Lidar instruments are aimed at a target using azimuth and elevation stages, then focus a beam of coherent, frequency modulated laser energy onto the target, such as the surface of a mechanical structure. Energy from the reflected beam is mixed with an optical reference signal that travels in a fiber path internal to the instrument, and the range to the target is calculated based on the difference in the frequency of the returned and reference signals. In cases when the parts are in extreme environments, additional steps need to be taken to separate the operator and lidar from that environment. A model has been developed that accurately reduces the lidar data to an absolute position and accounts for the three media in the testbed air, fused silica, and vacuum but the approach can be adapted for any environment or material. The accuracy of laser metrology measurements depends upon knowing the parameters of the media through which the measurement beam travels. Under normal conditions, this means knowledge of the temperature, pressure, and humidity of the air in the measurement volume. In the past, chamber windows have been used to separate the measuring device from the extreme environment within the chamber and still permit optical measurement, but, so far, only relative changes have been diagnosed. The ability to make accurate measurements through a window presents a challenge as there are a number of factors to consider. In the case of the lidar, the window will increase the time-of-flight of the laser beam causing a ranging error, and refract the direction of the beam causing angular positioning errors. In addition, differences in pressure, temperature, and humidity on each side of the window will cause slight atmospheric index changes and induce deformation and a refractive index gradient within the window. Also, since the window is a

  8. High accuracy autonomous navigation using the global positioning system (GPS)

    NASA Technical Reports Server (NTRS)

    Truong, Son H.; Hart, Roger C.; Shoan, Wendy C.; Wood, Terri; Long, Anne C.; Oza, Dipak H.; Lee, Taesul

    1997-01-01

    The application of global positioning system (GPS) technology to the improvement of the accuracy and economy of spacecraft navigation, is reported. High-accuracy autonomous navigation algorithms are currently being qualified in conjunction with the GPS attitude determination flyer (GADFLY) experiment for the small satellite technology initiative Lewis spacecraft. Preflight performance assessments indicated that these algorithms are able to provide a real time total position accuracy of better than 10 m and a velocity accuracy of better than 0.01 m/s, with selective availability at typical levels. It is expected that the position accuracy will be increased to 2 m if corrections are provided by the GPS wide area augmentation system.

  9. System providing limit switch function with simultaneous absolute position output

    NASA Technical Reports Server (NTRS)

    Alhorn, Dean C. (Inventor); Howard, David E. (Inventor); Smith, Dennis A. (Inventor)

    2006-01-01

    A limit and position sensing system includes a sensor assembly and an emitter. The sensor assembly includes first and second electrical conductors arranged in opposing parallel planes. The first electrical conductor is coiled outwardly from either end thereof in a clockwise fashion to form a first coil region and a second coil region. The second electrical conductor forms a single coil with portions of the single coil's rings lying between the first end and second end of the first electrical conductor being parallel to an axis of the first electrical conductor's plane. Ferromagnetic material is aligned with the first and second electrical conductors and spans beyond (a) the first and second ends of the first electrical conductor, and (b) the portions of the rings of the second electrical conductor's single coil that lie between the first end and second end of the first electrical conductor. The emitter is spaced apart from the sensor assembly and transmits a periodic electromagnetic wave towards the sensor assembly.

  10. Absolute thickness metrology with submicrometer accuracy using a low-coherence distance measuring interferometer.

    PubMed

    Zhao, Yang; Schmidt, Greg; Moore, Duncan T; Ellis, Jonathan D

    2015-09-01

    Absolute physical thickness across the sample aperture is critical in determining the index of a refraction profile from the optical path length profile for gradient index (GRIN) materials, which have a designed inhomogeneous refractive index. Motivated by this application, instrumentation was established to measure the absolute thickness of samples with nominally plane-parallel surfaces up to 50 mm thick. The current system is capable of measuring absolute thickness with 120 nm (1σ) repeatability and submicrometer expanded measurement uncertainty. Beside GRIN materials, this method is also capable of measuring other inhomogeneous and opaque materials. PMID:26368894

  11. SHAPES - Spatial, high-accuracy, position-encoding sensor

    NASA Technical Reports Server (NTRS)

    Nerheim, Noble M.; Blue, Randel C.

    1992-01-01

    Future space systems will require control sensors capable of real-time measurements of position coordinates of many structural locations. Applications for such a sensor include figure and vibration control, rendezvous and docking, and structure assembly verification. The paper discusses an experimental study of SHAPES (spatial, high-accuracy, position-encoding sensor), a 3D position sensor that provides range and two angular positions of laser-illuminated retroreflector targets that mark the locations to be measured. Simultaneous range measurements to multiple targets by a time-of-flight corelation of short laser pulses are made with a CCD-equipped streak tube. Angular positions are measured with a CCD camera. Position measurements of 24 targets with sub-millimeter range accuracy at a 10 Hz update rate have been demonstrated.

  12. COMPASS time synchronization and dissemination—Toward centimetre positioning accuracy

    NASA Astrophysics Data System (ADS)

    Wang, ZhengBo; Zhao, Lu; Wang, ShiGuang; Zhang, JianWei; Wang, Bo; Wang, LiJun

    2014-09-01

    In this paper we investigate methods to achieve highly accurate time synchronization among the satellites of the COMPASS global navigation satellite system (GNSS). Owing to the special design of COMPASS which implements several geo-stationary satellites (GEO), time synchronization can be highly accurate via microwave links between ground stations to the GEO satellites. Serving as space-borne relay stations, the GEO satellites can further disseminate time and frequency signals to other satellites such as the inclined geo-synchronous (IGSO) and mid-earth orbit (MEO) satellites within the system. It is shown that, because of the accuracy in clock synchronization, the theoretical accuracy of COMPASS positioning and navigation will surpass that of the GPS. In addition, the COMPASS system can function with its entire positioning, navigation, and time-dissemination services even without the ground link, thus making it much more robust and secure. We further show that time dissemination using the COMPASS-GEO satellites to earth-fixed stations can achieve very high accuracy, to reach 100 ps in time dissemination and 3 cm in positioning accuracy, respectively. In this paper, we also analyze two feasible synchronization plans. All special and general relativistic effects related to COMPASS clocks frequency and time shifts are given. We conclude that COMPASS can reach centimeter-level positioning accuracy and discuss potential applications.

  13. Operating a real time high accuracy positioning system

    NASA Astrophysics Data System (ADS)

    Johnston, G.; Hanley, J.; Russell, D.; Vooght, A.

    2003-04-01

    The paper shall review the history and development of real time DGPS services prior to then describing the design of a high accuracy GPS commercial augmentation system and service currently delivering over a wide area to users of precise positioning products. The infrastructure and system shall be explained in relation to the need for high accuracy and high integrity of positioning for users. A comparison of the different techniques for the delivery of data shall be provided to outline the technical approach taken. Examples of the performance of the real time system shall be shown in various regions and modes to outline the current achievable accuracies. Having described and established the current GPS based situation, a review of the potential of the Galileo system shall be presented. Following brief contextual information relating to the Galileo project, core system and services, the paper will identify possible key applications and the main user communities for sub decimetre level precise positioning. The paper will address the Galileo and modernised GPS signals in space that are relevant to commercial precise positioning for the future and will discuss the implications for precise positioning performance. An outline of the proposed architecture shall be described and associated with pointers towards a successful implementation. Central to this discussion will be an assessment of the likely evolution of system infrastructure and user equipment implementation, prospects for new applications and their effect upon the business case for precise positioning services.

  14. Absolute Binding Free Energy Calculations: On the Accuracy of Computational Scoring of Protein-ligand Interactions

    PubMed Central

    Singh, Nidhi; Warshel, Arieh

    2010-01-01

    Calculating the absolute binding free energies is a challenging task. Reliable estimates of binding free energies should provide a guide for rational drug design. It should also provide us with deeper understanding of the correlation between protein structure and its function. Further applications may include identifying novel molecular scaffolds and optimizing lead compounds in computer-aided drug design. Available options to evaluate the absolute binding free energies range from the rigorous but expensive free energy perturbation to the microscopic Linear Response Approximation (LRA/β version) and its variants including the Linear Interaction Energy (LIE) to the more approximated and considerably faster scaled Protein Dipoles Langevin Dipoles (PDLD/S-LRA version), as well as the less rigorous Molecular Mechanics Poisson–Boltzmann/Surface Area (MM/PBSA) and Generalized Born/Surface Area (MM/GBSA) to the less accurate scoring functions. There is a need for an assessment of the performance of different approaches in terms of computer time and reliability. We present a comparative study of the LRA/β, the LIE, the PDLD/S-LRA/β and the more widely used MM/PBSA and assess their abilities to estimate the absolute binding energies. The LRA and LIE methods perform reasonably well but require specialized parameterization for the non-electrostatic term. On the average, the PDLD/S-LRA/β performs effectively. Our assessment of the MM/PBSA is less optimistic. This approach appears to provide erroneous estimates of the absolute binding energies due to its incorrect entropies and the problematic treatment of electrostatic energies. Overall, the PDLD/S-LRA/β appears to offer an appealing option for the final stages of massive screening approaches. PMID:20186976

  15. Absolute instability from linear conversion of counter-propagating positive and negative energy waves

    SciTech Connect

    Kaufman, A.N.; Brizard, A.J.; Morehead, J.J.; Tracy, E.R.

    1997-12-31

    The resonant interaction of a negative-energy wave with a positive-energy wave gives rise to a linear instability. Whereas a single crossing of rays in a nonuniform medium leads to a convectively saturated instability, we show that a double crossing can yield an absolute instability.

  16. Theoretical Positioning Accuracy for Serial and Parallel Kinematic Structure

    NASA Astrophysics Data System (ADS)

    Kurekova, Eva; Halaj, Martin; Omachelová, Milada; Martišovitš, Ilja

    2014-10-01

    Modern production machines employ complex kinematic structures that shall enhance their performance. As those machines are very sophisticated electro-mechanical structures, their design is time consuming and financially demanding. Therefore, designers search for new possibilities how to estimate future properties of the machine as early as in the design phase. The paper gives a brief introduction to the adoption of methodology of measurement uncertainties into the design of production machines. The adapted methodology enables to estimate the theoretical positioning accuracy of the machine end effector that is one of the important indicators of machine performance. Both serial and parallel kinematic structures are considered in the paper. Methodology and sample calculations of theoretical positioning accuracy are presented for serial kinematic structure (represented by advanced plasma cutting head) and parallel kinematic structure, represented by one specific design named Tricept.

  17. Absolute continuity for operator valued completely positive maps on C*-algebras

    SciTech Connect

    Gheondea, Aurelian; Kavruk, Ali Samil

    2009-02-15

    Motivated by applicability to quantum operations, quantum information, and quantum probability, we investigate the notion of absolute continuity for operator valued completely positive maps on C*-algebras, previously introduced by Parthasarathy [in Athens Conference on Applied Probability and Time Series Analysis I (Springer-Verlag, Berlin, 1996), pp. 34-54]. We obtain an intrinsic definition of absolute continuity, we show that the Lebesgue decomposition defined by Parthasarathy is the maximal one among all other Lebesgue-type decompositions and that this maximal Lebesgue decomposition does not depend on the jointly dominating completely positive map, we obtain more flexible formulas for calculating the maximal Lebesgue decomposition, and we point out the nonuniqueness of the Lebesgue decomposition as well as a sufficient condition for uniqueness. In addition, we consider Radon-Nikodym derivatives for absolutely continuous completely positive maps that, in general, are unbounded positive self-adjoint operators affiliated to a certain von Neumann algebra, and we obtain a spectral approximation by bounded Radon-Nikodym derivatives. An application to the existence of the infimum of two completely positive maps is indicated, and formulas in terms of Choi's matrices for the Lebesgue decomposition of completely positive maps in matrix algebras are obtained.

  18. Positioning Accuracy in Otosurgery Measured with Optical Tracking

    PubMed Central

    Óvári, Attila; Neményi, Dóra; Just, Tino; Schuldt, Tobias; Buhr, Anne; Mlynski, Robert; Csókay, András; Pau, Hans-Wilhelm; Valálik, István

    2016-01-01

    Objectives To assess positioning accuracy in otosurgery and to test the impact of the two-handed instrument holding technique and the instrument support technique on surgical precision. To test an otologic training model with optical tracking. Study Design In total, 14 ENT surgeons in the same department with different levels of surgical experience performed static and dynamic tasks with otologic microinstruments under simulated otosurgical conditions. Methods Tip motion of the microinstrument was registered in three dimensions by optical tracking during 10 different tasks simulating surgical steps such as prosthesis crimping and dissection of the middle ear using formalin-fixed temporal bone. Instrument marker trajectories were compared within groups of experienced and less experienced surgeons performing uncompensated or compensated exercises. Results Experienced surgeons have significantly better positioning accuracy than novice ear surgeons in terms of mean displacement values of marker trajectories. The instrument support and the two-handed instrument holding techniques significantly reduce surgeons’ tremor. The laboratory set-up presented in this study provides precise feedback for otosurgeons about their surgical skills and proved to be a useful device for otosurgical training. Conclusions Simple tremor compensation techniques may offer trainees the potential to improve their positioning accuracy to the level of more experienced surgeons. Training in an experimental otologic environment with optical tracking may aid acquisition of technical skills in middle ear surgery and potentially shorten the learning curve. Thus, simulated exercises of surgical steps should be integrated into the training of otosurgeons. PMID:27027500

  19. Assessing the Accuracy of the Precise Point Positioning Technique

    NASA Astrophysics Data System (ADS)

    Bisnath, S. B.; Collins, P.; Seepersad, G.

    2012-12-01

    The Precise Point Positioning (PPP) GPS data processing technique has developed over the past 15 years to become a standard method for growing categories of positioning and navigation applications. The technique relies on single receiver point positioning combined with the use of precise satellite orbit and clock information and high-fidelity error modelling. The research presented here uniquely addresses the current accuracy of the technique, explains the limits of performance, and defines paths to improvements. For geodetic purposes, performance refers to daily static position accuracy. PPP processing of over 80 IGS stations over one week results in few millimetre positioning rms error in the north and east components and few centimetres in the vertical (all one sigma values). Larger error statistics for real-time and kinematic processing are also given. GPS PPP with ambiguity resolution processing is also carried out, producing slight improvements over the float solution results. These results are categorised into quality classes in order to analyse the root error causes of the resultant accuracies: "best", "worst", multipath, site displacement effects, satellite availability and geometry, etc. Also of interest in PPP performance is solution convergence period. Static, conventional solutions are slow to converge, with approximately 35 minutes required for 95% of solutions to reach the 20 cm or better horizontal accuracy. Ambiguity resolution can significantly reduce this period without biasing solutions. The definition of a PPP error budget is a complex task even with the resulting numerical assessment, as unlike the epoch-by-epoch processing in the Standard Position Service, PPP processing involving filtering. An attempt is made here to 1) define the magnitude of each error source in terms of range, 2) transform ranging error to position error via Dilution Of Precision (DOP), and 3) scale the DOP through the filtering process. The result is a deeper

  20. Accuracy of WAAS-enabled GPS for the determination of position and speed over ground.

    PubMed

    Witte, T H; Wilson, A M

    2005-08-01

    The Global Positioning System (GPS) offers many advantages over conventional methods for the determination of subject speed during biomechanical studies. Recent advances in GPS technology, in particular the implementation of the Wide-Angle Augmentation System and European Geostationary Navigation Overlay Service (WAAS/EGNOS), mean that small, highly portable units are available offering the potential of superior accuracy in the determination of both position and speed. This study set out to examine the accuracy of a WAAS-enabled GPS unit for the determination of position and speed. Comparison with the new and published data showed significant enhancements in both position and speed accuracy over a non-WAAS system. Position data collected during straight line cycling showed significantly lower sample-to-sample variation (mean absolute deviation from straight line 0.11 vs. 0.78 m) and greater repeatability from trial to trial (mean absolute deviation from actual path 0.37 vs. 4.8 m) for the WAAS-enabled unit compared to the non-WAAS unit. The speed determined by the WAAS-enabled GPS receiver during cycling in a straight line was within 0.2 ms(-1) of the actual speed measured for 57% of the values with 82% lying within 0.4 ms(-1), however, the data tended towards underestimation of speed during circle cycling, with 65% of values within 0.2 ms(-1) and 87% within 0.4 ms(-1) of the actual value. Local dGPS and dual frequency techniques are more accurate still, however, traditional differential GPS (dGPS), employing FM radio transmission of correction data to a separate receiver, now offers no advantage over WAAS and appears redundant.

  1. Rotational positioning measurement for the absolute angle based on a hetero-core fiber optics sensor

    NASA Astrophysics Data System (ADS)

    Nishiyama, Michiko; Watanabe, Kazuhiro

    2009-10-01

    We proposed a new approach to measure the rotational angle and describe how the rotational positioning sensor could be devised arranging the hetero-core fiber-optic macro-bending sensors in terms of detecting the absolute rotational angle. The hetero-core fiber optic sensor has many advantages such as ability of macro-bend sensing with optical intensity-based measurement, single-mode transmission basis and independence of temperature fluctuation for external environment. Therefore, it is suitable that the rotational positioning sensor is fabricated with the hetero-core fiber-optic technique. We designed two types of the absolute rotational position sensor modules to convert the absolute rotational angle to the displacement. The result showed that the proposed rotational positioning modules were sufficiently sensitive to the given rotational angle with monotonic loss change characteristics. The hetero-core rotational positioning sensors were successfully perceptive with typical sensitivities approximately 0.77 and 0.71 dB in the rotational angle ranges of 60 - 360 and 60 - 180 degrees. The deviation of the module in the range of 60 - 180 degrees induced 1.74 % that corresponded to 2.13 degrees.

  2. Horizontal Positional Accuracy of Google Earth's High-Resolution Imagery Archive

    PubMed Central

    Potere, David

    2008-01-01

    Google Earth now hosts high-resolution imagery that spans twenty percent of the Earth's landmass and more than a third of the human population. This contemporary high-resolution archive represents a significant, rapidly expanding, cost-free and largely unexploited resource for scientific inquiry. To increase the scientific utility of this archive, we address horizontal positional accuracy (georegistration) by comparing Google Earth with Landsat GeoCover scenes over a global sample of 436 control points located in 109 cities worldwide. Landsat GeoCover is an orthorectified product with known absolute positional accuracy of less than 50 meters root-mean-squared error (RMSE). Relative to Landsat GeoCover, the 436 Google Earth control points have a positional accuracy of 39.7 meters RMSE (error magnitudes range from 0.4 to 171.6 meters). The control points derived from satellite imagery have an accuracy of 22.8 meters RMSE, which is significantly more accurate than the 48 control-points based on aerial photography (41.3 meters RMSE; t-test p-value < 0.01). The accuracy of control points in more-developed countries is 24.1 meters RMSE, which is significantly more accurate than the control points in developing countries (44.4 meters RMSE; t-test p-value < 0.01). These findings indicate that Google Earth high-resolution imagery has a horizontal positional accuracy that is sufficient for assessing moderate-resolution remote sensing products across most of the world's peri-urban areas.

  3. Approximating relational observables by absolute quantities: a quantum accuracy-size trade-off

    NASA Astrophysics Data System (ADS)

    Miyadera, Takayuki; Loveridge, Leon; Busch, Paul

    2016-05-01

    The notion that any physical quantity is defined and measured relative to a reference frame is traditionally not explicitly reflected in the theoretical description of physical experiments where, instead, the relevant observables are typically represented as ‘absolute’ quantities. However, the emergence of the resource theory of quantum reference frames as a new branch of quantum information science in recent years has highlighted the need to identify the physical conditions under which a quantum system can serve as a good reference. Here we investigate the conditions under which, in quantum theory, an account in terms of absolute quantities can provide a good approximation of relative quantities. We find that this requires the reference system to be large in a suitable sense.

  4. Absolute Position Sensing Based on a Robust Differential Capacitive Sensor with a Grounded Shield Window.

    PubMed

    Bai, Yang; Lu, Yunfeng; Hu, Pengcheng; Wang, Gang; Xu, Jinxin; Zeng, Tao; Li, Zhengkun; Zhang, Zhonghua; Tan, Jiubin

    2016-01-01

    A simple differential capacitive sensor is provided in this paper to measure the absolute positions of length measuring systems. By utilizing a shield window inside the differential capacitor, the measurement range and linearity range of the sensor can reach several millimeters. What is more interesting is that this differential capacitive sensor is only sensitive to one translational degree of freedom (DOF) movement, and immune to the vibration along the other two translational DOFs. In the experiment, we used a novel circuit based on an AC capacitance bridge to directly measure the differential capacitance value. The experimental result shows that this differential capacitive sensor has a sensitivity of 2 × 10(-4) pF/μm with 0.08 μm resolution. The measurement range of this differential capacitive sensor is 6 mm, and the linearity error are less than 0.01% over the whole absolute position measurement range. PMID:27187393

  5. Absolute Position Sensing Based on a Robust Differential Capacitive Sensor with a Grounded Shield Window

    PubMed Central

    Bai, Yang; Lu, Yunfeng; Hu, Pengcheng; Wang, Gang; Xu, Jinxin; Zeng, Tao; Li, Zhengkun; Zhang, Zhonghua; Tan, Jiubin

    2016-01-01

    A simple differential capacitive sensor is provided in this paper to measure the absolute positions of length measuring systems. By utilizing a shield window inside the differential capacitor, the measurement range and linearity range of the sensor can reach several millimeters. What is more interesting is that this differential capacitive sensor is only sensitive to one translational degree of freedom (DOF) movement, and immune to the vibration along the other two translational DOFs. In the experiment, we used a novel circuit based on an AC capacitance bridge to directly measure the differential capacitance value. The experimental result shows that this differential capacitive sensor has a sensitivity of 2 × 10−4 pF/μm with 0.08 μm resolution. The measurement range of this differential capacitive sensor is 6 mm, and the linearity error are less than 0.01% over the whole absolute position measurement range. PMID:27187393

  6. Absolute Position Sensing Based on a Robust Differential Capacitive Sensor with a Grounded Shield Window.

    PubMed

    Bai, Yang; Lu, Yunfeng; Hu, Pengcheng; Wang, Gang; Xu, Jinxin; Zeng, Tao; Li, Zhengkun; Zhang, Zhonghua; Tan, Jiubin

    2016-05-11

    A simple differential capacitive sensor is provided in this paper to measure the absolute positions of length measuring systems. By utilizing a shield window inside the differential capacitor, the measurement range and linearity range of the sensor can reach several millimeters. What is more interesting is that this differential capacitive sensor is only sensitive to one translational degree of freedom (DOF) movement, and immune to the vibration along the other two translational DOFs. In the experiment, we used a novel circuit based on an AC capacitance bridge to directly measure the differential capacitance value. The experimental result shows that this differential capacitive sensor has a sensitivity of 2 × 10(-4) pF/μm with 0.08 μm resolution. The measurement range of this differential capacitive sensor is 6 mm, and the linearity error are less than 0.01% over the whole absolute position measurement range.

  7. Absolute accuracy of the Cyberware WB4 whole-body scanner

    NASA Astrophysics Data System (ADS)

    Daanen, Hein A. M.; Taylor, Stacie E.; Brunsman, Matthew A.; Nurre, Joseph H.

    1997-03-01

    The Cyberware WB4 whole body scanner is one of the first scanning systems in the world that generates a high resolution data set of the outer surface of the human body. The Computerized Anthropometric Research and Design (CARD) Laboratory of Wright-Patterson AFB intends to use the scanner to enable quick and reliable acquisition of anthropometric data. For this purpose, a validation study was initiated to check the accuracy, reliability and errors of the system. A calibration object, consisting of two boxes and a cylinder, was scanned in several locations in the scanning space. The object dimensions in the resulting scans compared favorably to the actual dimensions of the calibration object.

  8. Accuracy of patient positioning in mantle field irradiation.

    PubMed

    Creutzberg, C L; Visser, A G; De Porre, P M; Meerwaldt, J H; Althof, V G; Levendag, P C

    1992-04-01

    A prospective study of the accuracy of patient positioning in mantle field irradiation was carried out in 13 lymphoma patients treated with curative radiotherapy. Patients were treated in the supine and prone position for anterior and posterior fields, respectively. Individually shaped divergent shielding blocks were placed in a fixed position in a template which was positioned on a tray above the patient. A total number of 94 megavoltage portal films (MV) was analysed and compared to 26 simulation films (SIM). MV-SIM differences were larger for posterior fields than for anterior fields. Regarding the position of the lung shielding blocks, mean MV-SIM differences ranged from 1.3 to 4.4 mm and errors exceeding 1 cm were found in 7.2% of cases. Most discrepancies appeared to be randomly distributed. A 4-5 mm systematic cranial shift of patients in the posterior treatment position was noted. Discrepancies in the position of the laryngeal block, spinal cord shielding block and humerus blocks were small with mean MV-SIM differences ranging from 0.3 to 2.7 mm. Differences between simulation set-up and treatment set-up were modest as compared to error rates reported in the literature. Shielding of tumour-bearing areas did not occur. It was concluded that the present standardised technique of patient positioning and the design of treatment fields results in acceptable error rates. Attention should be directed towards increasing the stability of patients in the prone treatment position in order to further reduce both systematic and random error rates. PMID:1609130

  9. Accuracy of patient positioning in mantle field irradiation.

    PubMed

    Creutzberg, C L; Visser, A G; De Porre, P M; Meerwaldt, J H; Althof, V G; Levendag, P C

    1992-04-01

    A prospective study of the accuracy of patient positioning in mantle field irradiation was carried out in 13 lymphoma patients treated with curative radiotherapy. Patients were treated in the supine and prone position for anterior and posterior fields, respectively. Individually shaped divergent shielding blocks were placed in a fixed position in a template which was positioned on a tray above the patient. A total number of 94 megavoltage portal films (MV) was analysed and compared to 26 simulation films (SIM). MV-SIM differences were larger for posterior fields than for anterior fields. Regarding the position of the lung shielding blocks, mean MV-SIM differences ranged from 1.3 to 4.4 mm and errors exceeding 1 cm were found in 7.2% of cases. Most discrepancies appeared to be randomly distributed. A 4-5 mm systematic cranial shift of patients in the posterior treatment position was noted. Discrepancies in the position of the laryngeal block, spinal cord shielding block and humerus blocks were small with mean MV-SIM differences ranging from 0.3 to 2.7 mm. Differences between simulation set-up and treatment set-up were modest as compared to error rates reported in the literature. Shielding of tumour-bearing areas did not occur. It was concluded that the present standardised technique of patient positioning and the design of treatment fields results in acceptable error rates. Attention should be directed towards increasing the stability of patients in the prone treatment position in order to further reduce both systematic and random error rates.

  10. Correction to Method of Establishing the Absolute Radiometric Accuracy of Remote Sensing Systems While On-orbit Using Characterized Stellar Sources

    NASA Technical Reports Server (NTRS)

    Bowen, Howard S.; Cunningham, Douglas M.

    2007-01-01

    The contents include: 1) Brief history of related events; 2) Overview of original method used to establish absolute radiometric accuracy of remote sensing instruments using stellar sources; and 3) Considerations to improve the stellar calibration approach.

  11. Cadastral Positioning Accuracy Improvement: a Case Study in Malaysia

    NASA Astrophysics Data System (ADS)

    Hashim, N. M.; Omar, A. H.; Omar, K. M.; Abdullah, N. M.; Yatim, M. H. M.

    2016-09-01

    Cadastral map is a parcel-based information which is specifically designed to define the limitation of boundaries. In Malaysia, the cadastral map is under authority of the Department of Surveying and Mapping Malaysia (DSMM). With the growth of spatial based technology especially Geographical Information System (GIS), DSMM decided to modernize and reform its cadastral legacy datasets by generating an accurate digital based representation of cadastral parcels. These legacy databases usually are derived from paper parcel maps known as certified plan. The cadastral modernization will result in the new cadastral database no longer being based on single and static parcel paper maps, but on a global digital map. Despite the strict process of the cadastral modernization, this reform has raised unexpected queries that remain essential to be addressed. The main focus of this study is to review the issues that have been generated by this transition. The transformed cadastral database should be additionally treated to minimize inherent errors and to fit them to the new satellite based coordinate system with high positional accuracy. This review result will be applied as a foundation for investigation to study the systematic and effectiveness method for Positional Accuracy Improvement (PAI) in cadastral database modernization.

  12. Accuracy of the modified Hardinge approach in acetabular positioning

    PubMed Central

    Goyal, Prateek; Lau, Adrian; McCalden, Richard; Teeter, Matthew G.; Howard, James L.; Lanting, Brent A.

    2016-01-01

    Background The surgical approach chosen for total hip arthroplasty (THA) may affect the positioning of the acetabular component. The purpose of this study was to examine the accuracy in orienting the acetabular component using the modified Hardinge approach. Methods We used our institutional arthroplasty database to identify patients with primary, press-fit, hemispherical acetabular components of a metal-on-polyethylene THA performed between 2003 and 2011. Patients with radiographs obtained 1–3 years after the index procedure were included for measurement of anteversion and inclination angles. Acceptable values of anteversion and abduction angles were defined as 15° ± 10° and 40° ± 10°, respectively. Results We identified 1241 patients from the database, and the modified Hardinge approach was used in 1010 of the patients included in our analysis. The acetabular component was anteverted in the acceptable zone in 54.1% of patients. The abduction angle was within the defined range in 79.2% of patients. Combined anteversion and abduction angles within the defined zone were present in 43.6% of patients. Conclusion Consistent with studies examining accuracy from other approaches, our study reveals that the modified Hardinge approach was only moderately accurate in positioning the acetabular component in the acceptable zone. PMID:27240130

  13. Parametric Characterization of SGP4 Theory and TLE Positional Accuracy

    NASA Astrophysics Data System (ADS)

    Oltrogge, D.; Ramrath, J.

    2014-09-01

    Two-Line Elements, or TLEs, contain mean element state vectors compatible with General Perturbations (GP) singly-averaged semi-analytic orbit theory. This theory, embodied in the SGP4 orbit propagator, provides sufficient accuracy for some (but perhaps not all) orbit operations and SSA tasks. For more demanding tasks, higher accuracy orbit and force model approaches (i.e. Special Perturbations numerical integration or SP) may be required. In recent times, the suitability of TLEs or GP theory for any SSA analysis has been increasingly questioned. Meanwhile, SP is touted as being of high quality and well-suited for most, if not all, SSA applications. Yet the lack of truth or well-known reference orbits that haven't already been adopted for radar and optical sensor network calibration has typically prevented a truly unbiased assessment of such assertions. To gain better insight into the practical limits of applicability for TLEs, SGP4 and the underlying GP theory, the native SGP4 accuracy is parametrically examined for the statistically-significant range of RSO orbit inclinations experienced as a function of all orbit altitudes from LEO through GEO disposal altitude. For each orbit altitude, reference or truth orbits were generated using full force modeling, time-varying space weather, and AGIs HPOP numerical integration orbit propagator. Then, TLEs were optimally fit to these truth orbits. The resulting TLEs were then propagated and positionally differenced with the truth orbits to determine how well the GP theory was able to fit the truth orbits. Resultant statistics characterizing these empirically-derived accuracies are provided. This TLE fit process of truth orbits was intentionally designed to be similar to the JSpOC process operationally used to generate Enhanced GP TLEs for debris objects. This allows us to draw additional conclusions of the expected accuracies of EGP TLEs. In the real world, Orbit Determination (OD) programs aren't provided with dense optical

  14. Precision and accuracy in the quantitative analysis of biological samples by accelerator mass spectrometry: application in microdose absolute bioavailability studies.

    PubMed

    Gao, Lan; Li, Jing; Kasserra, Claudia; Song, Qi; Arjomand, Ali; Hesk, David; Chowdhury, Swapan K

    2011-07-15

    Determination of the pharmacokinetics and absolute bioavailability of an experimental compound, SCH 900518, following a 89.7 nCi (100 μg) intravenous (iv) dose of (14)C-SCH 900518 2 h post 200 mg oral administration of nonradiolabeled SCH 900518 to six healthy male subjects has been described. The plasma concentration of SCH 900518 was measured using a validated LC-MS/MS system, and accelerator mass spectrometry (AMS) was used for quantitative plasma (14)C-SCH 900518 concentration determination. Calibration standards and quality controls were included for every batch of sample analysis by AMS to ensure acceptable quality of the assay. Plasma (14)C-SCH 900518 concentrations were derived from the regression function established from the calibration standards, rather than directly from isotopic ratios from AMS measurement. The precision and accuracy of quality controls and calibration standards met the requirements of bioanalytical guidance (U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research, Center for Veterinary Medicine. Guidance for Industry: Bioanalytical Method Validation (ucm070107), May 2001. http://www.fda.gov/downloads/Drugs/GuidanceCompilanceRegulatoryInformation/Guidances/ucm070107.pdf ). The AMS measurement had a linear response range from 0.0159 to 9.07 dpm/mL for plasma (14)C-SCH 900158 concentrations. The CV and accuracy were 3.4-8.5% and 94-108% (82-119% for the lower limit of quantitation (LLOQ)), respectively, with a correlation coefficient of 0.9998. The absolute bioavailability was calculated from the dose-normalized area under the curve of iv and oral doses after the plasma concentrations were plotted vs the sampling time post oral dose. The mean absolute bioavailability of SCH 900518 was 40.8% (range 16.8-60.6%). The typical accuracy and standard deviation in AMS quantitative analysis of drugs from human plasma samples have been reported for the first time, and the impact of these

  15. Fundamental physics and absolute positioning metrology with the MAGIA lunar orbiter

    NASA Astrophysics Data System (ADS)

    Dell'Agnello, Simone; Lops, Caterina; Delle Monache, Giovanni O.; Currie, Douglas G.; Martini, Manuele; Vittori, Roberto; Coradini, Angioletta; Dionisio, Cesare; Garattini, Marco; Boni, Alessandro; Cantone, Claudio; March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Maiello, Mauro; Porcelli, Luca; Berardi, Simone; Intaglietta, Nicola

    2011-10-01

    MAGIA is a mission approved by the Italian Space Agency (ASI) for Phase A study. Using a single large-diameter laser retroreflector, a large laser retroreflector array and an atomic clock onboard MAGIA we propose to perform several fundamental physics and absolute positioning metrology experiments: VESPUCCI, an improved test of the gravitational redshift in the Earth-Moon system predicted by General Relativity; MoonLIGHT-P, a precursor test of a second generation Lunar Laser Ranging (LLR) payload for precision gravity and lunar science measurements under development for NASA, ASI and robotic missions of the proposed International Lunar Network (ILN); Selenocenter (the center of mass of the Moon), the determination of the position of the Moon center of mass with respect to the International Terrestrial Reference Frame/System (ITRF/ITRS); this will be compared to the one from Apollo and Lunokhod retroreflectors on the surface; MapRef, the absolute referencing of MAGIA's lunar altimetry, gravity and geochemical maps with respect to the ITRF/ITRS. The absolute positioning of MAGIA will be achieved thanks to: (1) the laboratory characterization of the retroreflector performance at INFN-LNF; (2) the precision tracking by the International Laser Ranging Service (ILRS), which gives two fundamental contributions to the ITRF/ITRS, i.e. the metrological definition of the geocenter (the Earth center of mass) and of the scale of length; (3) the radio science and accelerometer payloads; (4) support by the ASI Space Geodesy Center in Matera, Italy. Future ILN geodetic nodes equipped with MoonLIGHT and the Apollo/Lunokhod retroreflectors will become the first realization of the International Moon Reference Frame (IMRF), the lunar analog of the ITRF.

  16. SAR image registration in absolute coordinates using GPS carrier phase position and velocity information

    SciTech Connect

    Burgett, S.; Meindl, M.

    1994-09-01

    It is useful in a variety of military and commercial application to accurately register the position of synthetic aperture radar (SAR) imagery in absolute coordinates. The two basic SAR measurements, range and doppler, can be used to solve for the position of the SAR image. Imprecise knowledge of the SAR collection platform`s position and velocity vectors introduce errors in the range and doppler measurements and can cause the apparent location of the SAR image on the ground to be in error by tens of meters. Recent advances in carrier phase GPS techniques can provide an accurate description of the collection vehicle`s trajectory during the image formation process. In this paper, highly accurate carrier phase GPS trajectory information is used in conjunction with SAR imagery to demonstrate a technique for accurate registration of SAR images in WGS-84 coordinates. Flight test data will be presented that demonstrates SAR image registration errors of less than 4 meters.

  17. Accuracy of perioperative mandibular positions in orthognathic surgery.

    PubMed

    Borba, A M; Ribeiro-Junior, O; Brozoski, M A; Cé, P S; Espinosa, M M; Deboni, M C Z; Miloro, M; Naclério-Homem, M G

    2014-08-01

    Mandibular position is an important parameter used for the diagnosis of dentofacial deformities, as well as for orthognathic surgery planning and execution. Centric relation (anterior and superior relationship of the mandibular condyles interposed by the thinnest portion of their disks against the articular eminencies), centric occlusion (when lower teeth contact upper teeth at centric relation), and maximal intercuspation (complete interdigitation of lower and upper teeth) are not often addressed as factors that influence the results of orthognathic surgery, although these relationships are critical to ensure accuracy during the surgery. The present study assessed occlusal measurements taken before and after the induction of general anaesthesia from consecutive orthognathic surgery subjects. The variables assessed included the differences between these occlusal measurements, patient age, gender, type of deformity, and type of proposed orthognathic surgical procedure. The results demonstrated statistically significant differences for mandibular retrusion from maximal intercuspation to centric occlusion position, whereas the mandible appeared not to change significantly from centric occlusion after the induction of general anaesthesia. Patient age and the type of deformity appeared to influence the results. While in most instances centric occlusion can be adequately reproduced under general anaesthesia, for some specific orthognathic cases more accurate results might be obtained if the mandible-first sequence is used.

  18. Vehicle Position Estimation Based on Magnetic Markers: Enhanced Accuracy by Compensation of Time Delays

    PubMed Central

    Byun, Yeun-Sub; Jeong, Rag-Gyo; Kang, Seok-Won

    2015-01-01

    The real-time recognition of absolute (or relative) position and orientation on a network of roads is a core technology for fully automated or driving-assisted vehicles. This paper presents an empirical investigation of the design, implementation, and evaluation of a self-positioning system based on a magnetic marker reference sensing method for an autonomous vehicle. Specifically, the estimation accuracy of the magnetic sensing ruler (MSR) in the up-to-date estimation of the actual position was successfully enhanced by compensating for time delays in signal processing when detecting the vertical magnetic field (VMF) in an array of signals. In this study, the signal processing scheme was developed to minimize the effects of the distortion of measured signals when estimating the relative positional information based on magnetic signals obtained using the MSR. In other words, the center point in a 2D magnetic field contour plot corresponding to the actual position of magnetic markers was estimated by tracking the errors between pre-defined reference models and measured magnetic signals. The algorithm proposed in this study was validated by experimental measurements using a test vehicle on a pilot network of roads. From the results, the positioning error was found to be less than 0.04 m on average in an operational test. PMID:26580622

  19. Vehicle Position Estimation Based on Magnetic Markers: Enhanced Accuracy by Compensation of Time Delays.

    PubMed

    Byun, Yeun-Sub; Jeong, Rag-Gyo; Kang, Seok-Won

    2015-01-01

    The real-time recognition of absolute (or relative) position and orientation on a network of roads is a core technology for fully automated or driving-assisted vehicles. This paper presents an empirical investigation of the design, implementation, and evaluation of a self-positioning system based on a magnetic marker reference sensing method for an autonomous vehicle. Specifically, the estimation accuracy of the magnetic sensing ruler (MSR) in the up-to-date estimation of the actual position was successfully enhanced by compensating for time delays in signal processing when detecting the vertical magnetic field (VMF) in an array of signals. In this study, the signal processing scheme was developed to minimize the effects of the distortion of measured signals when estimating the relative positional information based on magnetic signals obtained using the MSR. In other words, the center point in a 2D magnetic field contour plot corresponding to the actual position of magnetic markers was estimated by tracking the errors between pre-defined reference models and measured magnetic signals. The algorithm proposed in this study was validated by experimental measurements using a test vehicle on a pilot network of roads. From the results, the positioning error was found to be less than 0.04 m on average in an operational test. PMID:26580622

  20. Absolute reliability of isokinetic knee flexion and extension measurements adopting a prone position.

    PubMed

    Ayala, F; De Ste Croix, M; Sainz de Baranda, P; Santonja, F

    2013-01-01

    The main purpose of this study was to determine the absolute and relative reliability of isokinetic peak torque (PT), angle of peak torque (APT), average power (PW) and total work (TW) for knee flexion and extension during concentric and eccentric actions measured in a prone position at 60, 180 and 240° s(-1). A total of 50 recreational athletes completed the study. PT, APT, PW and TW for concentric and eccentric knee extension and flexion were recorded at three different angular velocities (60, 180 and 240° s(-1)) on three different occasions with a 72- to 96-h rest interval between consecutive testing sessions. Absolute reliability was examined through typical percentage error (CV(TE)), percentage change in the mean (ChM) and relative reliability with intraclass correlations (ICC(3,1)). For both the knee extensor and flexor muscle groups, all strength data (except APT during knee flexion movements) demonstrated moderate absolute reliability (ChM < 3%; ICCs > 0·70; and CV(TE) < 20%) independent of the knee movement (flexion and extension), type of muscle action (concentric and eccentric) and angular velocity (60, 180 and 240° s(-1)). Therefore, the current study suggests that the CV(TE) values reported for PT (8-20%), APT (8-18%) (only during knee extension movements), PW (14-20%) and TW (12-28%) may be acceptable to detect the large changes usually observed after rehabilitation programmes, but not acceptable to examine the effect of preventative training programmes in healthy individuals.

  1. Hybrid position/force and positional accuracy controller for a hydraulic manipulator

    NASA Astrophysics Data System (ADS)

    Unruh, Stanley G.; Faddis, Terry N.; Greenway, Bryan R.; Hibbard, Wilthea

    1995-12-01

    A hybrid position/force controller is presented for a 6 DOF hydraulic manipulator. The controller has been implemented on a Kraft telerobotic slave which has been modified to accommodate a 6 DOF force/torque sensor at the wrist. The controller is implemented within the task frame, and both the position and force are controlled with a non-conventional hybrid control method. Positional accuracy control is maintained at the joint level by using a joint error prediction method based on measured joint torques which have been low-pass filtered. This prediction method eliminates the need for integral gains, which introduce unwanted limit cycling. Dynamic stability is maintained and Cartesian positional error is held to less than 0.2 inches. Conventional hybrid control is based on the ability to control joint torques, but hydraulic actuator torque can not generally be directly controlled. We instead employ a feedback loop which adjusts positional commands along force controlled DOFs until desired end effector force/,moments have been realized. This feedback loop has been implemented in both joint and Cartesian space. The joint space feedback method is based on the observed joint error verses joint torque characteristics used in the positional accuracy control portion. The joint space method has better force tracking capabilities than the Cartesian method, but is not stable for all robot configurations. Cartesian space feedback method has sufficient force tracking for a useful range of tasks, and is stable for all configurations.

  2. The Impact of Strategy Instruction and Timing of Estimates on Low and High Working-Memory Capacity Readers' Absolute Monitoring Accuracy

    ERIC Educational Resources Information Center

    Linderholm, Tracy; Zhao, Qin

    2008-01-01

    Working-memory capacity, strategy instruction, and timing of estimates were investigated for their effects on absolute monitoring accuracy, which is the difference between estimated and actual reading comprehension test performance. Participants read two expository texts under one of two randomly assigned reading strategy instruction conditions…

  3. How a GNSS Receiver Is Held May Affect Static Horizontal Position Accuracy.

    PubMed

    Weaver, Steven A; Ucar, Zennure; Bettinger, Pete; Merry, Krista

    2015-01-01

    The static horizontal position accuracy of a mapping-grade GNSS receiver was tested in two forest types over two seasons, and subsequently was tested in one forest type against open sky conditions in the winter season. The main objective was to determine whether the holding position during data collection would result in significantly different static horizontal position accuracy. Additionally, we wanted to determine whether the time of year (season), forest type, or environmental variables had an influence on accuracy. In general, the F4Devices Flint GNSS receiver was found to have mean static horizontal position accuracy levels within the ranges typically expected for this general type of receiver (3 to 5 m) when differential correction was not employed. When used under forest cover, in some cases the GNSS receiver provided a higher level of static horizontal position accuracy when held vertically, as opposed to held at an angle or horizontally (the more natural positions), perhaps due to the orientation of the antenna within the receiver, or in part due to multipath or the inability to use certain satellite signals. Therefore, due to the fact that numerous variables may affect static horizontal position accuracy, we only conclude that there is weak to moderate evidence that the results of holding position are significant. Statistical test results also suggest that the season of data collection had no significant effect on static horizontal position accuracy, and results suggest that atmospheric variables had weak correlation with horizontal position accuracy. Forest type was found to have a significant effect on static horizontal position accuracy in one aspect of one test, yet otherwise there was little evidence that forest type affected horizontal position accuracy. Since the holding position was found in some cases to be significant with regard to the static horizontal position accuracy of positions collected in forests, it may be beneficial to have an

  4. How a GNSS Receiver Is Held May Affect Static Horizontal Position Accuracy

    PubMed Central

    Weaver, Steven A.; Ucar, Zennure; Bettinger, Pete; Merry, Krista

    2015-01-01

    The static horizontal position accuracy of a mapping-grade GNSS receiver was tested in two forest types over two seasons, and subsequently was tested in one forest type against open sky conditions in the winter season. The main objective was to determine whether the holding position during data collection would result in significantly different static horizontal position accuracy. Additionally, we wanted to determine whether the time of year (season), forest type, or environmental variables had an influence on accuracy. In general, the F4Devices Flint GNSS receiver was found to have mean static horizontal position accuracy levels within the ranges typically expected for this general type of receiver (3 to 5 m) when differential correction was not employed. When used under forest cover, in some cases the GNSS receiver provided a higher level of static horizontal position accuracy when held vertically, as opposed to held at an angle or horizontally (the more natural positions), perhaps due to the orientation of the antenna within the receiver, or in part due to multipath or the inability to use certain satellite signals. Therefore, due to the fact that numerous variables may affect static horizontal position accuracy, we only conclude that there is weak to moderate evidence that the results of holding position are significant. Statistical test results also suggest that the season of data collection had no significant effect on static horizontal position accuracy, and results suggest that atmospheric variables had weak correlation with horizontal position accuracy. Forest type was found to have a significant effect on static horizontal position accuracy in one aspect of one test, yet otherwise there was little evidence that forest type affected horizontal position accuracy. Since the holding position was found in some cases to be significant with regard to the static horizontal position accuracy of positions collected in forests, it may be beneficial to have an

  5. Tracking Accuracy of a Real-Time Fiducial Tracking System for Patient Positioning and Monitoring in Radiation Therapy

    SciTech Connect

    Shchory, Tal; Schifter, Dan; Lichtman, Rinat; Neustadter, David; Corn, Benjamin W.

    2010-11-15

    Purpose: In radiation therapy there is a need to accurately know the location of the target in real time. A novel radioactive tracking technology has been developed to answer this need. The technology consists of a radioactive implanted fiducial marker designed to minimize migration and a linac mounted tracking device. This study measured the static and dynamic accuracy of the new tracking technology in a clinical radiation therapy environment. Methods and Materials: The tracking device was installed on the linac gantry. The radioactive marker was located in a tissue equivalent phantom. Marker location was measured simultaneously by the radioactive tracking system and by a Microscribe G2 coordinate measuring machine (certified spatial accuracy of 0.38 mm). Localization consistency throughout a volume and absolute accuracy in the Fixed coordinate system were measured at multiple gantry angles over volumes of at least 10 cm in diameter centered at isocenter. Dynamic accuracy was measured with the marker located inside a breathing phantom. Results: The mean consistency for the static source was 0.58 mm throughout the tested region at all measured gantry angles. The mean absolute position error in the Fixed coordinate system for all gantry angles was 0.97 mm. The mean real-time tracking error for the dynamic source within the breathing phantom was less than 1 mm. Conclusions: This novel radioactive tracking technology has the potential to be useful in accurate target localization and real-time monitoring for radiation therapy.

  6. Optimal Design of the Absolute Positioning Sensor for a High-Speed Maglev Train and Research on Its Fault Diagnosis

    PubMed Central

    Zhang, Dapeng; Long, Zhiqiang; Xue, Song; Zhang, Junge

    2012-01-01

    This paper studies an absolute positioning sensor for a high-speed maglev train and its fault diagnosis method. The absolute positioning sensor is an important sensor for the high-speed maglev train to accomplish its synchronous traction. It is used to calibrate the error of the relative positioning sensor which is used to provide the magnetic phase signal. On the basis of the analysis for the principle of the absolute positioning sensor, the paper describes the design of the sending and receiving coils and realizes the hardware and the software for the sensor. In order to enhance the reliability of the sensor, a support vector machine is used to recognize the fault characters, and the signal flow method is used to locate the faulty parts. The diagnosis information not only can be sent to an upper center control computer to evaluate the reliability of the sensors, but also can realize on-line diagnosis for debugging and the quick detection when the maglev train is off-line. The absolute positioning sensor we study has been used in the actual project. PMID:23112619

  7. Optimal design of the absolute positioning sensor for a high-speed maglev train and research on its fault diagnosis.

    PubMed

    Zhang, Dapeng; Long, Zhiqiang; Xue, Song; Zhang, Junge

    2012-01-01

    This paper studies an absolute positioning sensor for a high-speed maglev train and its fault diagnosis method. The absolute positioning sensor is an important sensor for the high-speed maglev train to accomplish its synchronous traction. It is used to calibrate the error of the relative positioning sensor which is used to provide the magnetic phase signal. On the basis of the analysis for the principle of the absolute positioning sensor, the paper describes the design of the sending and receiving coils and realizes the hardware and the software for the sensor. In order to enhance the reliability of the sensor, a support vector machine is used to recognize the fault characters, and the signal flow method is used to locate the faulty parts. The diagnosis information not only can be sent to an upper center control computer to evaluate the reliability of the sensors, but also can realize on-line diagnosis for debugging and the quick detection when the maglev train is off-line. The absolute positioning sensor we study has been used in the actual project.

  8. Global positioning system measurements for crustal deformation: Precision and accuracy

    USGS Publications Warehouse

    Prescott, W.H.; Davis, J.L.; Svarc, J.L.

    1989-01-01

    Analysis of 27 repeated observations of Global Positioning System (GPS) position-difference vectors, up to 11 kilometers in length, indicates that the standard deviation of the measurements is 4 millimeters for the north component, 6 millimeters for the east component, and 10 to 20 millimeters for the vertical component. The uncertainty grows slowly with increasing vector length. At 225 kilometers, the standard deviation of the measurement is 6, 11, and 40 millimeters for the north, east, and up components, respectively. Measurements with GPS and Geodolite, an electromagnetic distance-measuring system, over distances of 10 to 40 kilometers agree within 0.2 part per million. Measurements with GPS and very long baseline interferometry of the 225-kilometer vector agree within 0.05 part per million.

  9. Global positioning system measurements for crustal deformation: precision and accuracy.

    PubMed

    Prescott, W H; Davis, J L; Svarc, J L

    1989-06-16

    Analysis of 27 repeated observations of Global Positioning System (GPS) position-difference vectors, up to 11 kilometers in length, indicates that the standard deviation of the measurements is 4 millimeters for the north component, 6 millimeters for the east component, and 10 to 20 millimeters for the vertical component. The uncertainty grows slowly with increasing vector length. At 225 kilometers, the standard deviation of the measurement is 6, 11, and 40 millimeters for the north, east, and up components, respectively. Measurements with GPS and Geodolite, an electromagnetic distance-measuring system, over distances of 10 to 40 kilometers agree within 0.2 part per million. Measurements with GPS and very long baseline interferometry of the 225-kilometer vector agree within 0.05 part per million. PMID:17820661

  10. Effects of spacecraft reflections on RF interferometer position location accuracy

    NASA Technical Reports Server (NTRS)

    Wallace, R. G.; Ward, F. C.

    1984-01-01

    This report describes one of three study tasks related to the application of an RF interferometer aboard a low-orbiting spacecraft to determine the location of ground-based transmitters. Computer modeling was used to estimate the error in the measured signal angle-of-arrival caused by reflection and diffraction off the spacecraft. Existing computer codes (NEC-BSC) were modified and used to determine the perturbation, due to the spacecraft, in the phase difference between two interferometer antennas, suspended on either side of the spacecraft. This phase perturbation was found as a function of the angle-of-arrival of the signal from a far-field source. The spacecraft antennas were assumed to be circularly polarized with a cardioid pattern. It was found that the perturbation was as much 12.4 deg within the + or - 60 deg field-of-view. This suggests that phase calibration and correction of phase measurements are essential for precision position location using this technique.

  11. An evaluation of the accuracy of geomagnetic data obtained from an unattended, automated, quasi-absolute station

    USGS Publications Warehouse

    Herzog, D.C.

    1990-01-01

    A comparison is made of geomagnetic calibration data obtained from a high-sensitivity proton magnetometer enclosed within an orthogonal bias coil system, with data obtained from standard procedures at a mid-latitude U.S. Geological Survey magnetic observatory using a quartz horizontal magnetometer, a Ruska magnetometer, and a total field magnetometer. The orthogonal coil arrangement is used with the proton magnetometer to provide Deflected-Inclination-Deflected-Declination (DIDD) data from which quasi-absolute values of declination, horizontal intensity, and vertical intensity can be derived. Vector magnetometers provide the ordinate values to yield baseline calibrations for both the DIDD and standard observatory processes. Results obtained from a prototype system over a period of several months indicate that the DIDD unit can furnish adequate absolute field values for maintaining observatory calibration data, thus providing baseline control for unattended, remote stations. ?? 1990.

  12. High-accuracy interferometer with a prism pair for measurement of the absolute refractive index of glass

    SciTech Connect

    Hori, Yasuaki; Hirai, Akiko; Minoshima, Kaoru; Matsumoto, Hirokazu

    2009-04-10

    We propose a variable-path interferometric technique for the measurement of the absolute refractive index of optical glasses. We use two interferometers to decide the ratio between changes in the optical path in a prism-shaped sample glass and in air resulting from displacement of the sample. The method allows precise measurements to be made without prior knowledge of the properties of the sample. The combined standard uncertainty of the proposed method is 1.6x10{sup -6}.

  13. Effect of self-vibration on accuracy of free-fall absolute gravity measurement with laser interferometer

    NASA Astrophysics Data System (ADS)

    Feng, Jin-yang; Wu, Shu-qing; Li, Chun-jian; Su, Duo-wu; Yu, Mei

    2015-02-01

    A free-fall absolute gravimeter was used to measure the gravity acceleration of a corner-cube released in high vacuum, and the gravity acceleration was determined by fitting the free-falling trajectories obtained through optical interferometry. During the measurement, the self-vibration of an absolute gravimeter caused ground vibration and the change in optical path length due to vibration of vacuum-air interface, which resulted in a measurement error. Numerical simulation was run by introducing vibration disturbance to the trajectories of free-fall. The effect of disturbance under different instrumental self-vibration conditions was analyzed. Simulation results indicated that the deviation of calculated gravity acceleration from the preset value and residuals amplitude after fitting depended on the amplitude and initial phase of the vibration disturbance. The deviation value and fitting residuals amplitude increased with the increasing of amplitude and there was a one-to-one correspondence between the two. The deviation of calculated gravity acceleration decreases by properly setting the initial phase difference of vibration disturbance with respect to the interference fringe signal.

  14. Absolute measurement of electron-cloud density in a positively charged particle beam.

    PubMed

    Kireeff Covo, Michel; Molvik, Arthur W; Friedman, Alex; Vay, Jean-Luc; Seidl, Peter A; Logan, Grant; Baca, David; Vujic, Jasmina L

    2006-08-01

    Clouds of stray electrons are ubiquitous in particle accelerators and frequently limit the performance of storage rings. Earlier measurements of electron energy distribution and flux to the walls provided only a relative electron-cloud density. We have measured electron accumulation using ions expelled by the beam. The ion energy distribution maps the depressed beam potential and gives the dynamic cloud density. Clearing electrode current reveals the static background cloud density, allowing the first absolute measurement of the time-dependent electron-cloud density during the beam pulse.

  15. Lorentzian’ analysis of the accuracy of modern catalogues of stellar positions

    NASA Astrophysics Data System (ADS)

    Varaksina, N. Y.; Nefedyev, Y. A.; Churkin, K. O.; Zabbarova, R. R.; Demin, S. A.

    2015-12-01

    There is a new approach for the estimation of the position accuracy and proper motions of the stars in astrometric catalogues by comparison of the stars' positions in the researched and Hipparcos catalogues in different periods, but under a standard equinox. To verify this method was carried out the analysis of the star positions and proper motions UCAC2, PPM, ACRS, Tycho-2, ACT, TRC, FON and Tycho catalogues. As a result of this study was obtained that the accuracy of positions and proper motions of the stars in Tycho-2 and UCAC2 catalogues are approximately equal. The results of the comparison are represented graphically.

  16. Improve the Absolute Accuracy of Ozone Intensities in the 9-11 μm Region via Mw/ir Multi-Wavelength Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yu, Shanshan; Drouin, Brian

    2016-06-01

    Ozone (O_3) is crucial for studies of air quality, human and crop health, and radiative forcing. Spectroscopic remote sensing techniques have been extensively employed to investigate ozone globally and regionally. Infrared intensities of ≤1% accuracy are desired by the remote sensing community. The accuracy of the current state-of-the-art infrared ozone intensities is on the order of 4-10%, resulting in ad hoc intensity scaling factors for consistent atmospheric retrievals. The large uncertainties on the infrared ozone intensities arise from the fact that pure ozone is very difficult to generate and sustain in the laboratory. Best estimates have employed IR/UV cross beam experiments to determine the accurate O_3 volume mixing ratio of the sample through its standard cross section value at 254 nm. This presentation reports our effort to improve the absolute accuracy of ozone intensities in the 9-11 μm region via a transfer of the precision of the rotational dipole moment onto the infrared measurement (MW/IR). Our approach was to use MW/IR cross beam experiments and determine the O_3 mixing ratio through alternately measuring pure rotation ozone lines from 692 to 779 GHz. The uncertainty of these pure rotation line intensities is better than 0.1%. The sample cell was a slow flow cross cell and the total pressure inside the sample cell was maintained constant through a proportional-integral-derivative (PID) flow control. Five infrared O_3 spectra were obtained, with a path length of 3.74 m, pressures ranging from 30 to 120 mTorr, and mixing ratio ranging from 0.5 to 0.9. A multi spectrum fitting technique was employed to fit all the FTS spectra simultaneously. The results show that we can determine intensities of the 9.6μm band with absolute accuracy better than 4%.

  17. SU-E-T-189: First Experimental Verification of the Accuracy of Absolute Dose Reconstruction From PET-CT Imaging of Yttrium 90 Microspheres

    SciTech Connect

    Veltchev, I; Fourkal, E; Doss, M; Ma, C; Meyer, J; Yu, M; Horwitz, E

    2014-06-01

    Purpose: In the past few years there have been numerous proposals for 3D dose reconstruction from the PET-CT imaging of patients undergoing radioembolization treatment of the liver with yttrium-90 microspheres. One of the most promising techniques uses convolution of the measured PET activity distribution with a pre-calculated Monte Carlo dose deposition kernel. The goal of the present study is to experimentally verify the accuracy of this method and to analyze the significance of various error sources. Methods: Optically stimulated luminescence detectors (OSLD) were used (NanoDot, Landauer) in this experiment. Two detectors were mounted on the central axis of a cylinder filled with water solution of yttrium-90 chloride. The total initial activity was 90mCi. The cylinder was inserted in a larger water phantom and scanned on a Siemens Biograph 16 Truepoint PET-CT scanner. Scans were performed daily over a period of 20 days to build a calibration curve for the measured absolute activity spanning 7 yttrium-90 half-lives. The OSLDs were mounted in the phantom for a predetermined period of time in order to record 2Gy dose. The measured dose was then compared to the dose reconstructed from the activity density at the location of each dosimeter. Results: Thorough error analysis of the dose reconstruction algorithm takes into account the uncertainties in the absolute PET activity, branching ratios, and nonlinearity of the calibration curve. The measured dose for 105-minute exposure on day 10 of the experiment was 219(11)cGy, while the reconstructed dose at the location of the detector was 215(47)cGy. Conclusion: We present the first experimental verification of the accuracy of the convolution algorithm for absolute dose reconstruction of yttrium-90 microspheres. The excellent agreement between the measured and calculated point doses will encourage the broad clinical adoption of the convolution-based dose reconstruction algorithm, making future quantitative dose

  18. Accuracy Analysis of a Low-Cost Platform for Positioning and Navigation

    NASA Astrophysics Data System (ADS)

    Hofmann, S.; Kuntzsch, C.; Schulze, M. J.; Eggert, D.; Sester, M.

    2012-07-01

    This paper presents an accuracy analysis of a platform based on low-cost components for landmark-based navigation intended for research and teaching purposes. The proposed platform includes a LEGO MINDSTORMS NXT 2.0 kit, an Android-based Smartphone as well as a compact laser scanner Hokuyo URG-04LX. The robot is used in a small indoor environment, where GNSS is not available. Therefore, a landmark map was produced in advance, with the landmark positions provided to the robot. All steps of procedure to set up the platform are shown. The main focus of this paper is the reachable positioning accuracy, which was analyzed in this type of scenario depending on the accuracy of the reference landmarks and the directional and distance measuring accuracy of the laser scanner. Several experiments were carried out, demonstrating the practically achievable positioning accuracy. To evaluate the accuracy, ground truth was acquired using a total station. These results are compared to the theoretically achievable accuracies and the laser scanner's characteristics.

  19. Combined adjustment of multi-resolution satellite imagery for improved geo-positioning accuracy

    NASA Astrophysics Data System (ADS)

    Tang, Shengjun; Wu, Bo; Zhu, Qing

    2016-04-01

    Due to the widespread availability of satellite imagery nowadays, it is common for regions to be covered by satellite imagery from multiple sources with multiple resolutions. This paper presents a combined adjustment approach to integrate multi-source multi-resolution satellite imagery for improved geo-positioning accuracy without the use of ground control points (GCPs). Instead of using all the rational polynomial coefficients (RPCs) of images for processing, only those dominating the geo-positioning accuracy are used in the combined adjustment. They, together with tie points identified in the images, are used as observations in the adjustment model. Proper weights are determined for each observation, and ridge parameters are determined for better convergence of the adjustment solution. The outputs from the combined adjustment are the improved dominating RPCs of images, from which improved geo-positioning accuracy can be obtained. Experiments using ZY-3, SPOT-7 and Pleiades-1 imagery in Hong Kong, and Cartosat-1 and Worldview-1 imagery in Catalonia, Spain demonstrate that the proposed method is able to effectively improve the geo-positioning accuracy of satellite images. The combined adjustment approach offers an alternative method to improve geo-positioning accuracy of satellite images. The approach enables the integration of multi-source and multi-resolution satellite imagery for generating more precise and consistent 3D spatial information, which permits the comparative and synergistic use of multi-resolution satellite images from multiple sources.

  20. The Positioning Accuracy of BAUV Using Fusion of Data from USBL System and Movement Parameters Measurements.

    PubMed

    Krzysztof, Naus; Aleksander, Nowak

    2016-08-15

    The article presents a study of the accuracy of estimating the position coordinates of BAUV (Biomimetic Autonomous Underwater Vehicle) by the extended Kalman filter (EKF) method. The fusion of movement parameters measurements and position coordinates fixes was applied. The movement parameters measurements are carried out by on-board navigation devices, while the position coordinates fixes are done by the USBL (Ultra Short Base Line) system. The problem of underwater positioning and the conceptual design of the BAUV navigation system constructed at the Naval Academy (Polish Naval Academy-PNA) are presented in the first part of the paper. The second part consists of description of the evaluation results of positioning accuracy, the genesis of the problem of selecting method for underwater positioning, and the mathematical description of the method of estimating the position coordinates using the EKF method by the fusion of measurements with on-board navigation and measurements obtained with the USBL system. The main part contains a description of experimental research. It consists of a simulation program of navigational parameter measurements carried out during the BAUV passage along the test section. Next, the article covers the determination of position coordinates on the basis of simulated parameters, using EKF and DR methods and the USBL system, which are then subjected to a comparative analysis of accuracy. The final part contains systemic conclusions justifying the desirability of applying the proposed fusion method of navigation parameters for the BAUV positioning.

  1. The Positioning Accuracy of BAUV Using Fusion of Data from USBL System and Movement Parameters Measurements.

    PubMed

    Krzysztof, Naus; Aleksander, Nowak

    2016-01-01

    The article presents a study of the accuracy of estimating the position coordinates of BAUV (Biomimetic Autonomous Underwater Vehicle) by the extended Kalman filter (EKF) method. The fusion of movement parameters measurements and position coordinates fixes was applied. The movement parameters measurements are carried out by on-board navigation devices, while the position coordinates fixes are done by the USBL (Ultra Short Base Line) system. The problem of underwater positioning and the conceptual design of the BAUV navigation system constructed at the Naval Academy (Polish Naval Academy-PNA) are presented in the first part of the paper. The second part consists of description of the evaluation results of positioning accuracy, the genesis of the problem of selecting method for underwater positioning, and the mathematical description of the method of estimating the position coordinates using the EKF method by the fusion of measurements with on-board navigation and measurements obtained with the USBL system. The main part contains a description of experimental research. It consists of a simulation program of navigational parameter measurements carried out during the BAUV passage along the test section. Next, the article covers the determination of position coordinates on the basis of simulated parameters, using EKF and DR methods and the USBL system, which are then subjected to a comparative analysis of accuracy. The final part contains systemic conclusions justifying the desirability of applying the proposed fusion method of navigation parameters for the BAUV positioning. PMID:27537884

  2. The Positioning Accuracy of BAUV Using Fusion of Data from USBL System and Movement Parameters Measurements

    PubMed Central

    Krzysztof, Naus; Aleksander, Nowak

    2016-01-01

    The article presents a study of the accuracy of estimating the position coordinates of BAUV (Biomimetic Autonomous Underwater Vehicle) by the extended Kalman filter (EKF) method. The fusion of movement parameters measurements and position coordinates fixes was applied. The movement parameters measurements are carried out by on-board navigation devices, while the position coordinates fixes are done by the USBL (Ultra Short Base Line) system. The problem of underwater positioning and the conceptual design of the BAUV navigation system constructed at the Naval Academy (Polish Naval Academy—PNA) are presented in the first part of the paper. The second part consists of description of the evaluation results of positioning accuracy, the genesis of the problem of selecting method for underwater positioning, and the mathematical description of the method of estimating the position coordinates using the EKF method by the fusion of measurements with on-board navigation and measurements obtained with the USBL system. The main part contains a description of experimental research. It consists of a simulation program of navigational parameter measurements carried out during the BAUV passage along the test section. Next, the article covers the determination of position coordinates on the basis of simulated parameters, using EKF and DR methods and the USBL system, which are then subjected to a comparative analysis of accuracy. The final part contains systemic conclusions justifying the desirability of applying the proposed fusion method of navigation parameters for the BAUV positioning. PMID:27537884

  3. Automated novel high-accuracy miniaturized positioning system for use in analytical instrumentation

    NASA Astrophysics Data System (ADS)

    Siomos, Konstadinos; Kaliakatsos, John; Apostolakis, Manolis; Lianakis, John; Duenow, Peter

    1996-01-01

    The development of three-dimensional automotive devices (micro-robots) for applications in analytical instrumentation, clinical chemical diagnostics and advanced laser optics, depends strongly on the ability of such a device: firstly to be positioned with high accuracy, reliability, and automatically, by means of user friendly interface techniques; secondly to be compact; and thirdly to operate under vacuum conditions, free of most of the problems connected with conventional micropositioners using stepping-motor gear techniques. The objective of this paper is to develop and construct a mechanically compact computer-based micropositioning system for coordinated motion in the X-Y-Z directions with: (1) a positioning accuracy of less than 1 micrometer, (the accuracy of the end-position of the system is controlled by a hard/software assembly using a self-constructed optical encoder); (2) a heat-free propulsion mechanism for vacuum operation; and (3) synchronized X-Y motion.

  4. Positional Accuracy of Airborne Integrated Global Positioning and Inertial Navigation Systems for Mapping in Glen Canyon, Arizona

    USGS Publications Warehouse

    Sanchez, Richard D.; Hothem, Larry D.

    2002-01-01

    High-resolution airborne and satellite image sensor systems integrated with onboard data collection based on the Global Positioning System (GPS) and inertial navigation systems (INS) may offer a quick and cost-effective way to gather accurate topographic map information without ground control or aerial triangulation. The Applanix Corporation?s Position and Orientation Solutions for Direct Georeferencing of aerial photography was used in this project to examine the positional accuracy of integrated GPS/INS for terrain mapping in Glen Canyon, Arizona. The research application in this study yielded important information on the usefulness and limits of airborne integrated GPS/INS data-capture systems for mapping.

  5. An effective approach to improving low-cost GPS positioning accuracy in real-time navigation.

    PubMed

    Islam, Md Rashedul; Kim, Jong-Myon

    2014-01-01

    Positioning accuracy is a challenging issue for location-based applications using a low-cost global positioning system (GPS). This paper presents an effective approach to improving the positioning accuracy of a low-cost GPS receiver for real-time navigation. The proposed method precisely estimates position by combining vehicle movement direction, velocity averaging, and distance between waypoints using coordinate data (latitude, longitude, time, and velocity) of the GPS receiver. The previously estimated precious reference point, coordinate translation, and invalid data check also improve accuracy. In order to evaluate the performance of the proposed method, we conducted an experiment using a GARMIN GPS 19xHVS receiver attached to a car and used Google Maps to plot the processed data. The proposed method achieved improvement of 4-10 meters in several experiments. In addition, we compared the proposed approach with two other state-of-the-art methods: recursive averaging and ARMA interpolation. The experimental results show that the proposed approach outperforms other state-of-the-art methods in terms of positioning accuracy.

  6. An Effective Approach to Improving Low-Cost GPS Positioning Accuracy in Real-Time Navigation

    PubMed Central

    Islam, Md. Rashedul; Kim, Jong-Myon

    2014-01-01

    Positioning accuracy is a challenging issue for location-based applications using a low-cost global positioning system (GPS). This paper presents an effective approach to improving the positioning accuracy of a low-cost GPS receiver for real-time navigation. The proposed method precisely estimates position by combining vehicle movement direction, velocity averaging, and distance between waypoints using coordinate data (latitude, longitude, time, and velocity) of the GPS receiver. The previously estimated precious reference point, coordinate translation, and invalid data check also improve accuracy. In order to evaluate the performance of the proposed method, we conducted an experiment using a GARMIN GPS 19xHVS receiver attached to a car and used Google Maps to plot the processed data. The proposed method achieved improvement of 4–10 meters in several experiments. In addition, we compared the proposed approach with two other state-of-the-art methods: recursive averaging and ARMA interpolation. The experimental results show that the proposed approach outperforms other state-of-the-art methods in terms of positioning accuracy. PMID:25136679

  7. The effect of different Global Navigation Satellite System methods on positioning accuracy in elite alpine skiing.

    PubMed

    Gilgien, Matthias; Spörri, Jörg; Limpach, Philippe; Geiger, Alain; Müller, Erich

    2014-10-03

    In sport science, Global Navigation Satellite Systems (GNSS) are frequently applied to capture athletes' position, velocity and acceleration. Application of GNSS includes a large range of different GNSS technologies and methods. To date no study has comprehensively compared the different GNSS methods applied. Therefore, the aim of the current study was to investigate the effect of differential and non-differential solutions, different satellite systems and different GNSS signal frequencies on position accuracy. Twelve alpine ski racers were equipped with high-end GNSS devices while performing runs on a giant slalom course. The skiers' GNSS antenna positions were calculated in three satellite signal obstruction conditions using five different GNSS methods. The GNSS antenna positions were compared to a video-based photogrammetric reference system over one turn and against the most valid GNSS method over the entire run. Furthermore, the time for acquisitioning differential GNSS solutions was assessed for four differential methods. The only GNSS method that consistently yielded sub-decimetre position accuracy in typical alpine skiing conditions was a differential method using American (GPS) and Russian (GLONASS) satellite systems and the satellite signal frequencies L1 and L2. Under conditions of minimal satellite signal obstruction, valid results were also achieved when either the satellite system GLONASS or the frequency L2 was dropped from the best configuration. All other methods failed to fulfill the accuracy requirements needed to detect relevant differences in the kinematics of alpine skiers, even in conditions favorable for GNSS measurements. The methods with good positioning accuracy had also the shortest times to compute differential solutions. This paper highlights the importance to choose appropriate methods to meet the accuracy requirements for sport applications.

  8. The Effect of Different Global Navigation Satellite System Methods on Positioning Accuracy in Elite Alpine Skiing

    PubMed Central

    Gilgien, Matthias; Spörri, Jörg; Limpach, Philippe; Geiger, Alain; Müller, Erich

    2014-01-01

    In sport science, Global Navigation Satellite Systems (GNSS) are frequently applied to capture athletes' position, velocity and acceleration. Application of GNSS includes a large range of different GNSS technologies and methods. To date no study has comprehensively compared the different GNSS methods applied. Therefore, the aim of the current study was to investigate the effect of differential and non-differential solutions, different satellite systems and different GNSS signal frequencies on position accuracy. Twelve alpine ski racers were equipped with high-end GNSS devices while performing runs on a giant slalom course. The skiers' GNSS antenna positions were calculated in three satellite signal obstruction conditions using five different GNSS methods. The GNSS antenna positions were compared to a video-based photogrammetric reference system over one turn and against the most valid GNSS method over the entire run. Furthermore, the time for acquisitioning differential GNSS solutions was assessed for four differential methods. The only GNSS method that consistently yielded sub-decimetre position accuracy in typical alpine skiing conditions was a differential method using American (GPS) and Russian (GLONASS) satellite systems and the satellite signal frequencies L1 and L2. Under conditions of minimal satellite signal obstruction, valid results were also achieved when either the satellite system GLONASS or the frequency L2 was dropped from the best configuration. All other methods failed to fulfill the accuracy requirements needed to detect relevant differences in the kinematics of alpine skiers, even in conditions favorable for GNSS measurements. The methods with good positioning accuracy had also the shortest times to compute differential solutions. This paper highlights the importance to choose appropriate methods to meet the accuracy requirements for sport applications. PMID:25285461

  9. Accuracy of velocities from repeated GPS surveys: relative positioning is concerned

    NASA Astrophysics Data System (ADS)

    Duman, Huseyin; Ugur Sanli, D.

    2016-04-01

    Over more than a decade, researchers have been interested in studying the accuracy of GPS positioning solutions. Recently, reporting the accuracy of GPS velocities has been added to this. Researchers studying landslide motion, tectonic motion, uplift, sea level rise, and subsidence still report results from GPS experiments in which repeated GPS measurements from short sessions are used. This motivated some other researchers to study the accuracy of GPS deformation rates/velocities from various repeated GPS surveys. In one of the efforts, the velocity accuracy was derived from repeated GPS static surveys using short observation sessions and Precise Point Positioning mode of GPS software. Velocities from short GPS sessions were compared with the velocities from 24 h sessions. The accuracy of velocities was obtained using statistical hypothesis testing and quantifying the accuracy of least squares estimation models. The results reveal that 45-60 % of the horizontal and none of the vertical solutions comply with the results from 24 h solutions. We argue that this case in which the data was evaluated using PPP should also apply to the case in which the data belonging to long GPS base lengths is processed using fundamental relative point positioning. To test this idea we chose the two IGS stations ANKR and NICO and derive their velocities from the reference stations held fixed in the stable EURASIAN plate. The University of Bern's GNSS software BERNESE was used to produce relative positioning solutions, and the results are compared with those of GIPSY/OASIS II PPP results. First impressions indicate that it is worth designing a global experiment and test these ideas in detail.

  10. APIC: Absolute Position Interfero Coronagraph for direct exoplanet detection: first laboratory results

    NASA Astrophysics Data System (ADS)

    Allouche, Fatmé; Glindemann, Andreas; Aristidi, Eric; Vakili, Farrokh

    2010-07-01

    For the detection and direct imaging of exoplanets, when the intensity ratio between a star and its orbiting planet can largely exceed 106, coronagraphic methods are mandatory. In 1996, a concept of achromatic interferocoronagraph (AIC) was presented by J. Gay and Y. Rabbia for the detection of very faint stellar companions, such as exoplanets. In an earlier paper, we presented a modified version of the AIC permitting to determine the relative position of these faint companions with respect to the parent star, a problem unsolved in the original design of the AIC. Our modification lied in the use of cylindrical lens doublets as field rotator. By placing two of them in one arm of the interferometric set-up of AIC, we destroyed the axis of symmetry induced by the AIC's original design. Our theoretical study, along with the numerical computations, presented then, and the preliminary test bench results aiming at validating the cylindrical lens doublet field rotation capability, presented in this paper, show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optic axis.

  11. Portable device to assess dynamic accuracy of global positioning systems (GPS) receivers used in agricultural aircraft

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A device was designed to test the dynamic accuracy of Global Positioning System (GPS) receivers used in aerial vehicles. The system works by directing a sun-reflected light beam from the ground to the aircraft using mirrors. A photodetector is placed pointing downward from the aircraft and circuitry...

  12. The Impact of Ionospheric Disturbances on High Accuracy Positioning in Brazil

    NASA Astrophysics Data System (ADS)

    Yang, L.; Park, J.; Susnik, A.; Aquino, M. H.; Dodson, A.

    2013-12-01

    High positioning accuracy is a key requirement to a number of applications with a high economic impact, such as precision agriculture, surveying, geodesy, land management, off-shore operations. Global Navigation Satellite Systems (GNSS) carrier phase measurement based techniques, such as Real Time Kinematic (RTK), Network-RTK (NRTK) and Precise Point Positioning (PPP), have played an important role in providing centimetre-level positioning accuracy, and become the core of the above applications. However these techniques are especially sensitive to ionospheric perturbations, in particular scintillation. Brazil sits in one of the most affected regions of the Earth and can be regarded as a test-bed for scenarios of the severe ionospheric condition. Over the Brazilian territory, the ionosphere behaves in a considerably unpredictable way and scintillation activity is very prominent, occurring especially after sunset hours. NRTK services may not be able to provide satisfactory accuracy, or even continuous positioning during strong scintillation periods. CALIBRA (Countering GNSS high Accuracy applications Limitations due to Ionospheric disturbances in BRAzil) started in late 2012 and is a project funded by the GSA (European GNSS Agency) and the European Commission under the Framework Program 7 to deliver improvements on carrier phase based high accuracy algorithms and their implementation in GNSS receivers, aiming to counter the adverse ionospheric effects over Brazil. As the first stage of this project, the ionospheric disturbances, which affect the applications of RTK, NRTK or PPP, are characterized. Typical problems include degraded positioning accuracy, difficulties in ambiguity fixing, NRTK network interpolation errors, long PPP convergence time etc. It will identify how GNSS observables and existing algorithms are degraded by ionosphere related phenomena, evaluating the impact on positioning techniques in terms of accuracy, integrity and availability. Through the

  13. Design of a contact probe with high positioning accuracy for plasmonic lithography.

    PubMed

    Jang, Jinhee; Kim, Yongwoo; Kim, Seok; Jung, Howon; Hahn, Jae Won

    2011-01-01

    Plasmonic lithography with a contact probe records nano-meter scale features and has high-throughput owing to its capability to scan in contact mode. The probe is commonly based on a micrometer-scale cantilever, which leads to the tip-positioning problem due to force-deflection that induces lateral tip displacement. We propose a geometrically modified probe to achieve high positioning accuracy. Contrary to a conventional cantilever-tip probe, we designed a "circular probe" with arc-shaped arms that hold the tip in the center. The mechanism is based on the "fixed-fixed beam" concept in material mechanics. To confirm its positioning accuracy, we used a finite element method (FEM) to calculate the tip displacement for a circular probe and compared the results with those using a conventional cantilever-tip probe. The probe was designed considering a silicon-based micro-fabrication process. The designed probe has a square outline boundary with a length of 50 µm, four arms, and a pyramidal tip with a height of 5 µm. The ratio of the lateral tip displacement to the vertical deflection was evaluated to indicate the accuracy of the probe. The probe has higher positioning accuracy by a factor of 10(3) and 10 in its approach mode and scan mode, respectively, compared with a cantilever-tip probe. We expect that the probe is suitable for the applications that require high positioning accuracy, such as nanolithography in contact mode and applications based on multiple-probe arrays. PMID:21445985

  14. Positioning Accuracy in Stereotactic Radiotherapy Using a Mask System With Added Vacuum Mouth Piece and Stereoscopic X-Ray Positioning

    SciTech Connect

    Santvoort, Jan van Wiggenraad, Ruud; Bos, Petra

    2008-09-01

    Purpose: For cranial patients receiving stereotactic radiotherapy, we use the Exactrac stereoscopic X-ray system to optimize patient positioning. Patients are immobilized with the BrainLAB Mask System (BrainLAB, Feldkirchen, Germany). We have developed an adapter to this system that accommodates a vacuum mouth piece (VMP). Measurements with the Exactrac system have been performed to study the positioning accuracy after corrections with this system and to evaluate the accuracy of the VMP vs. the standard available upper jaw support (UJS). Methods and Materials: Positioning results were collected for 20 patients with the UJS and 20 patients with the VMP, before treatment (1,122 fractions) and after treatment (400 fractions). For all 6 degrees of freedom the average, the random error and systematic error were calculated. Results: The average vector length before and after correction with the Exactrac system was 2.1 {+-} 1.2 mm and 0.7 {+-} 0.6 mm respectively for UJS and 1.7 {+-} 0.7 mm and 0.4 {+-} 0.4 mm for VMP. Interfraction positioning for translations was greatly improved after correction with the Exactrac system (p < 0.0005) and is better with VMP than with UJS (p = 0.005). Outliers were greatly reduced. Interfraction rotations were significantly smaller for VMP. Intrafraction errors for vertical and longitudinal translations and for rotations were smaller for the VMP. Conclusions: Positioning correction using the Exactrac X-ray system greatly improves accuracy. Adding the VMP results in even better patient fixation and smaller rotations, making it a useful addition to the Mask System. Combined, this is a convenient and accurate alternative to invasive fixation methods.

  15. High accuracy position response calibration method for a micro-channel plate ion detector

    NASA Astrophysics Data System (ADS)

    Hong, R.; Leredde, A.; Bagdasarova, Y.; Fléchard, X.; García, A.; Müller, P.; Knecht, A.; Liénard, E.; Kossin, M.; Sternberg, M. G.; Swanson, H. E.; Zumwalt, D. W.

    2016-11-01

    We have developed a position response calibration method for a micro-channel plate (MCP) detector with a delay-line anode position readout scheme. Using an in situ calibration mask, an accuracy of 8 μm and a resolution of 85 μm (FWHM) have been achieved for MeV-scale α particles and ions with energies of ∼10 keV. At this level of accuracy, the difference between the MCP position responses to high-energy α particles and low-energy ions is significant. The improved performance of the MCP detector can find applications in many fields of AMO and nuclear physics. In our case, it helps reducing systematic uncertainties in a high-precision nuclear β-decay experiment.

  16. Current issues on 3D volumetric positioning accuracy: measurement, compensation, and definition

    NASA Astrophysics Data System (ADS)

    Wang, C.

    2008-10-01

    Traditionally, manufacturers have ensured part accuracy by linear calibration of each machine tool axis. The conventional definition of the 3-D volumetric positioning error is the root mean square of the three-axis displacement error. 20 years ago, the dominate error is the lead screw pitch error of 3 axes. This definition is adequate. However, now the machine accuracy has been improved with better lead screw, linear encoder and compensation, the dominate errors become the squareness errors and straightness errors. Hence the above definition is inadequate. During the past years, the industry has seen demand emerge for the "volumetric accuracy" specification on machine tools. One hurdle remains: a standard definition so that everyone measures volumetric accuracy with the same yardstick. The issue has been discussed in many Standards Committees, machine tool builders and the metrology community. Reported here are, a new 3D volumetric positioning error measurement and compensation technique, proposed definitions or measures of 3 D volumetric positioning errors of a CNC machine tool, and its verification.

  17. SU-E-T-33: An EPID-Based Method for Testing Absolute Leaf Position for MLC Without Backup Jaws

    SciTech Connect

    Hancock, S; Whitaker, M

    2014-06-01

    Purpose: Methods in common use for MLC leaf position QA are limited to measurements relative to an arbitrary reference position. The authors previously presented an EPID-based method for efficiently testing accuracy of leaf position relative to the mechanical isocenter for MLC with backup jaws. The purpose of this work is to extend that method to the general case of MLC without backup jaws. Methods: A pair of collimator walkout images is used to determine the location of the mechanical isocenter relative to the center of one field using a parameter called X-offset. The method allows for shift of the imager panel to cover subsets of MLC leaves within the limited field of view of the imager. For a shifted panel position, an image of three beam strips defined by a subset of MLC leaves allows determination of the position of each leaf relative to the isocenter. The location of the isocenter is determined by applying X-offset to an image of a single rectangular field obtained at that panel position. The method can also be used to test backup jaws instead of MLC leaves. A software tool was developed to efficiently analyze the images. Results: The software tool reports leaf position and deviation from nominal position, and provides visual displays to facilitate rapid qualitative interpretation. Test results using this method agree well with results using the previous method requiring backup jaws. Test results have been successfully used to recalibrate one model MLC (Elekta MLCi2™). Work in progress includes extension of the software tool to other MLC models, and quantification of reproducibility of the measurements. Conclusion: This work successfully demonstrates a method to efficiently and accurately measure MLC leaf position, or backup jaw position, relative to the mechanical isocenter of the collimator.

  18. Enhanced Positioning Algorithm of ARPS for Improving Accuracy and Expanding Service Coverage

    PubMed Central

    Lee, Kyuman; Baek, Hoki; Lim, Jaesung

    2016-01-01

    The airborne relay-based positioning system (ARPS), which employs the relaying of navigation signals, was proposed as an alternative positioning system. However, the ARPS has limitations, such as relatively large vertical error and service restrictions, because firstly, the user position is estimated based on airborne relays that are located in one direction, and secondly, the positioning is processed using only relayed navigation signals. In this paper, we propose an enhanced positioning algorithm to improve the performance of the ARPS. The main idea of the enhanced algorithm is the adaptable use of either virtual or direct measurements of reference stations in the calculation process based on the structural features of the ARPS. Unlike the existing two-step algorithm for airborne relay and user positioning, the enhanced algorithm is divided into two cases based on whether the required number of navigation signals for user positioning is met. In the first case, where the number of signals is greater than four, the user first estimates the positions of the airborne relays and its own initial position. Then, the user position is re-estimated by integrating a virtual measurement of a reference station that is calculated using the initial estimated user position and known reference positions. To prevent performance degradation, the re-estimation is performed after determining its requirement through comparing the expected position errors. If the navigation signals are insufficient, such as when the user is outside of airborne relay coverage, the user position is estimated by additionally using direct signal measurements of the reference stations in place of absent relayed signals. The simulation results demonstrate that a higher accuracy level can be achieved because the user position is estimated based on the measurements of airborne relays and a ground station. Furthermore, the service coverage is expanded by using direct measurements of reference stations for user

  19. Enhanced Positioning Algorithm of ARPS for Improving Accuracy and Expanding Service Coverage.

    PubMed

    Lee, Kyuman; Baek, Hoki; Lim, Jaesung

    2016-01-01

    The airborne relay-based positioning system (ARPS), which employs the relaying of navigation signals, was proposed as an alternative positioning system. However, the ARPS has limitations, such as relatively large vertical error and service restrictions, because firstly, the user position is estimated based on airborne relays that are located in one direction, and secondly, the positioning is processed using only relayed navigation signals. In this paper, we propose an enhanced positioning algorithm to improve the performance of the ARPS. The main idea of the enhanced algorithm is the adaptable use of either virtual or direct measurements of reference stations in the calculation process based on the structural features of the ARPS. Unlike the existing two-step algorithm for airborne relay and user positioning, the enhanced algorithm is divided into two cases based on whether the required number of navigation signals for user positioning is met. In the first case, where the number of signals is greater than four, the user first estimates the positions of the airborne relays and its own initial position. Then, the user position is re-estimated by integrating a virtual measurement of a reference station that is calculated using the initial estimated user position and known reference positions. To prevent performance degradation, the re-estimation is performed after determining its requirement through comparing the expected position errors. If the navigation signals are insufficient, such as when the user is outside of airborne relay coverage, the user position is estimated by additionally using direct signal measurements of the reference stations in place of absent relayed signals. The simulation results demonstrate that a higher accuracy level can be achieved because the user position is estimated based on the measurements of airborne relays and a ground station. Furthermore, the service coverage is expanded by using direct measurements of reference stations for user

  20. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  1. Effects of attachment position and shoulder orientation during calibration on the accuracy of the acromial tracker.

    PubMed

    Shaheen, A F; Alexander, C M; Bull, A M J

    2011-04-29

    The acromial tracker is used to measure scapular rotations during dynamic movements. The method has low accuracy in high elevations and is sensitive to its attachment location on the acromion. The aim of this study was to investigate the effect of the attachment position and shoulder orientation during calibration on the tracker accuracy. The tracker was attached to one of three positions: near the anterior edge of the acromion process, just above the acromial angle and the meeting point between the acromion and the scapular spine. The scapula locator was used to track the scapula during bilateral abduction simultaneously. The locator was used to calibrate the tracker at: no abduction, 30°, 60°, 90° and 120° humerothoracic abduction. ANOVA tests compared RMS errors for different attachment positions and calibration angles. The results showed that attaching the device at the meeting point between the acromion and the scapular spine gave the smallest errors and it was best to calibrate the device at 60° for elevations ≤90°, at 120° for elevations >90° and at 90°or 120° for the full range of abduction. The accuracy of the tracker is significantly improved if attached appropriately and calibrated for the range of movement being measured.

  2. Accuracy in GPS/Acoustic positioning on a moored buoy moving around far from the optimal position

    NASA Astrophysics Data System (ADS)

    Imano, M.; Kido, M.; Ohta, Y.; Takahashi, N.; Fukuda, T.; Ochi, H.; Hino, R.

    2015-12-01

    For detecting the seafloor crustal deformation and Tsunami associated with large earthquakes in real-time, it is necessary to monitor them just above the possible source region. For this purpose, we have been dedicated in developing a real-time continuous observation system using a multi-purpose moored buoy. Sea-trials of the system have been carried out near the Nanakai trough in 2013 and 2014 (Takahashi et al., 2014). We especially focused on the GPS/Acoustic measurement (GPS/A) in the system for horizontal crustal movement. The GPS/A on a moored buoy has a critical drawback compared to the traditional ones, in which the data can be stacked over ranging points fixed at an optimal position. Accuracy in positioning with a single ranging from an arbitrary point is the subject to be improved in this study. Here, we report the positioning results in the buoy system using data in the 2014 sea-trial and demonstrate the improvement of the result. We also address the potential resolving power in the positioning using synthetic tests. The target GPS/A site consists of six seafloor transponders (PXPs) forming a small inner- and a large outer-triangles. The bottom of the moored cable is anchored nearly the center of the triangles. In the sea-trial, 11 times successive ranging was scheduled once a week, and we plotted positioning results from different buoy position. We confirmed that scatter in positioning using six PXPs simultaneously is ten times smaller than that using individual triangle separately. Next, we modified the definition of the PXP array geometry using data obtained in a campaign observation. Definition of an array geometry is insensitive as far as ranging is made in the same position, however, severely affects the positioning when ranging is made from various positions like the moored buoy. The modified PXP array is slightly smaller and 2m deeper than the original one. We found that the scatter of positioning results in the sea-trial is reduced from 4m to 1

  3. Accuracy improvement techniques in Precise Point Positioning method using multiple GNSS constellations

    NASA Astrophysics Data System (ADS)

    Vasileios Psychas, Dimitrios; Delikaraoglou, Demitris

    2016-04-01

    The future Global Navigation Satellite Systems (GNSS), including modernized GPS, GLONASS, Galileo and BeiDou, offer three or more signal carriers for civilian use and much more redundant observables. The additional frequencies can significantly improve the capabilities of the traditional geodetic techniques based on GPS signals at two frequencies, especially with regard to the availability, accuracy, interoperability and integrity of high-precision GNSS applications. Furthermore, highly redundant measurements can allow for robust simultaneous estimation of static or mobile user states including more parameters such as real-time tropospheric biases and more reliable ambiguity resolution estimates. This paper presents an investigation and analysis of accuracy improvement techniques in the Precise Point Positioning (PPP) method using signals from the fully operational (GPS and GLONASS), as well as the emerging (Galileo and BeiDou) GNSS systems. The main aim was to determine the improvement in both the positioning accuracy achieved and the time convergence it takes to achieve geodetic-level (10 cm or less) accuracy. To this end, freely available observation data from the recent Multi-GNSS Experiment (MGEX) of the International GNSS Service, as well as the open source program RTKLIB were used. Following a brief background of the PPP technique and the scope of MGEX, the paper outlines the various observational scenarios that were used in order to test various data processing aspects of PPP solutions with multi-frequency, multi-constellation GNSS systems. Results from the processing of multi-GNSS observation data from selected permanent MGEX stations are presented and useful conclusions and recommendations for further research are drawn. As shown, data fusion from GPS, GLONASS, Galileo and BeiDou systems is becoming increasingly significant nowadays resulting in a position accuracy increase (mostly in the less favorable East direction) and a large reduction of convergence

  4. Position Accuracy Improvement by Implementing the DGNSS-CP Algorithm in Smartphones.

    PubMed

    Yoon, Donghwan; Kee, Changdon; Seo, Jiwon; Park, Byungwoon

    2016-01-01

    The position accuracy of Global Navigation Satellite System (GNSS) modules is one of the most significant factors in determining the feasibility of new location-based services for smartphones. Considering the structure of current smartphones, it is impossible to apply the ordinary range-domain Differential GNSS (DGNSS) method. Therefore, this paper describes and applies a DGNSS-correction projection method to a commercial smartphone. First, the local line-of-sight unit vector is calculated using the elevation and azimuth angle provided in the position-related output of Android's LocationManager, and this is transformed to Earth-centered, Earth-fixed coordinates for use. To achieve position-domain correction for satellite systems other than GPS, such as GLONASS and BeiDou, the relevant line-of-sight unit vectors are used to construct an observation matrix suitable for multiple constellations. The results of static and dynamic tests show that the standalone GNSS accuracy is improved by about 30%-60%, thereby reducing the existing error of 3-4 m to just 1 m. The proposed algorithm enables the position error to be directly corrected via software, without the need to alter the hardware and infrastructure of the smartphone. This method of implementation and the subsequent improvement in performance are expected to be highly effective to portability and cost saving. PMID:27322284

  5. Position Accuracy Improvement by Implementing the DGNSS-CP Algorithm in Smartphones.

    PubMed

    Yoon, Donghwan; Kee, Changdon; Seo, Jiwon; Park, Byungwoon

    2016-06-18

    The position accuracy of Global Navigation Satellite System (GNSS) modules is one of the most significant factors in determining the feasibility of new location-based services for smartphones. Considering the structure of current smartphones, it is impossible to apply the ordinary range-domain Differential GNSS (DGNSS) method. Therefore, this paper describes and applies a DGNSS-correction projection method to a commercial smartphone. First, the local line-of-sight unit vector is calculated using the elevation and azimuth angle provided in the position-related output of Android's LocationManager, and this is transformed to Earth-centered, Earth-fixed coordinates for use. To achieve position-domain correction for satellite systems other than GPS, such as GLONASS and BeiDou, the relevant line-of-sight unit vectors are used to construct an observation matrix suitable for multiple constellations. The results of static and dynamic tests show that the standalone GNSS accuracy is improved by about 30%-60%, thereby reducing the existing error of 3-4 m to just 1 m. The proposed algorithm enables the position error to be directly corrected via software, without the need to alter the hardware and infrastructure of the smartphone. This method of implementation and the subsequent improvement in performance are expected to be highly effective to portability and cost saving.

  6. High-Accuracy Positioning of an Industrial Robot Using Image/PSD-Based Hybrid Servo Control

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Xi, Ning; Shen, Yantao

    2011-04-01

    This article presents a new and effective multi-sensor-based control strategy for high-accuracy/precision and high-efficiency automatic robot positioning in the field of industrial robot calibration. The strategy combines both coarsely visual servo and fine position-sensitive detector (PSD) servo control methods. In a large field of view, an image-based visual servo control system is employed to roughly guide the laser spot, which is from a single laser pointer attached to the end-effector of a robot to project to the segmented PSDs with a resolution of better than 0.1 µm. Once the laser spot is projected onto the active area of the PSD surface, the control will automatically be switched to the PSD feedback and servoing for fine positioning. An image/PSD-based servoing system has been presented. Based on the system, the controller design and switch logic of the hybrid servoing are given. The experimental results conducted on an ABB industrial robot IRB1600 verified the effectiveness of the developed visual/PSD hybrid servo controllers, as well as demonstrated that the high accuracy of 30 µm of robot positioning can be approached. The development of the hybrid control method and system has played a major role in achieving high-performance automatic robot calibration.

  7. Position Accuracy Improvement by Implementing the DGNSS-CP Algorithm in Smartphones

    PubMed Central

    Yoon, Donghwan; Kee, Changdon; Seo, Jiwon; Park, Byungwoon

    2016-01-01

    The position accuracy of Global Navigation Satellite System (GNSS) modules is one of the most significant factors in determining the feasibility of new location-based services for smartphones. Considering the structure of current smartphones, it is impossible to apply the ordinary range-domain Differential GNSS (DGNSS) method. Therefore, this paper describes and applies a DGNSS-correction projection method to a commercial smartphone. First, the local line-of-sight unit vector is calculated using the elevation and azimuth angle provided in the position-related output of Android’s LocationManager, and this is transformed to Earth-centered, Earth-fixed coordinates for use. To achieve position-domain correction for satellite systems other than GPS, such as GLONASS and BeiDou, the relevant line-of-sight unit vectors are used to construct an observation matrix suitable for multiple constellations. The results of static and dynamic tests show that the standalone GNSS accuracy is improved by about 30%–60%, thereby reducing the existing error of 3–4 m to just 1 m. The proposed algorithm enables the position error to be directly corrected via software, without the need to alter the hardware and infrastructure of the smartphone. This method of implementation and the subsequent improvement in performance are expected to be highly effective to portability and cost saving. PMID:27322284

  8. Estimated results analysis and application of the precise point positioning based high-accuracy ionosphere delay

    NASA Astrophysics Data System (ADS)

    Wang, Shi-tai; Peng, Jun-huan

    2015-12-01

    The characterization of ionosphere delay estimated with precise point positioning is analyzed in this paper. The estimation, interpolation and application of the ionosphere delay are studied based on the processing of 24-h data from 5 observation stations. The results show that the estimated ionosphere delay is affected by the hardware delay bias from receiver so that there is a difference between the estimated and interpolated results. The results also show that the RMSs (root mean squares) are bigger, while the STDs (standard deviations) are better than 0.11 m. When the satellite difference is used, the hardware delay bias can be canceled. The interpolated satellite-differenced ionosphere delay is better than 0.11 m. Although there is a difference between the between the estimated and interpolated ionosphere delay results it cannot affect its application in single-frequency positioning and the positioning accuracy can reach cm level.

  9. Multi-sensor fusion with interacting multiple model filter for improved aircraft position accuracy.

    PubMed

    Cho, Taehwan; Lee, Changho; Choi, Sangbang

    2013-01-01

    The International Civil Aviation Organization (ICAO) has decided to adopt Communications, Navigation, and Surveillance/Air Traffic Management (CNS/ATM) as the 21st century standard for navigation. Accordingly, ICAO members have provided an impetus to develop related technology and build sufficient infrastructure. For aviation surveillance with CNS/ATM, Ground-Based Augmentation System (GBAS), Automatic Dependent Surveillance-Broadcast (ADS-B), multilateration (MLAT) and wide-area multilateration (WAM) systems are being established. These sensors can track aircraft positions more accurately than existing radar and can compensate for the blind spots in aircraft surveillance. In this paper, we applied a novel sensor fusion method with Interacting Multiple Model (IMM) filter to GBAS, ADS-B, MLAT, and WAM data in order to improve the reliability of the aircraft position. Results of performance analysis show that the position accuracy is improved by the proposed sensor fusion method with the IMM filter.

  10. Mapping stream habitats with a global positioning system: Accuracy, precision, and comparison with traditional methods

    USGS Publications Warehouse

    Dauwalter, D.C.; Fisher, W.L.; Belt, K.C.

    2006-01-01

    We tested the precision and accuracy of the Trimble GeoXT??? global positioning system (GPS) handheld receiver on point and area features and compared estimates of stream habitat dimensions (e.g., lengths and areas of riffles and pools) that were made in three different Oklahoma streams using the GPS receiver and a tape measure. The precision of differentially corrected GPS (DGPS) points was not affected by the number of GPS position fixes (i.e., geographic location estimates) averaged per DGPS point. Horizontal error of points ranged from 0.03 to 2.77 m and did not differ with the number of position fixes per point. The error of area measurements ranged from 0.1% to 110.1% but decreased as the area increased. Again, error was independent of the number of position fixes averaged per polygon corner. The estimates of habitat lengths, widths, and areas did not differ when measured using two methods of data collection (GPS and a tape measure), nor did the differences among methods change at three stream sites with contrasting morphologies. Measuring features with a GPS receiver was up to 3.3 times faster on average than using a tape measure, although signal interference from high streambanks or overhanging vegetation occasionally limited satellite signal availability and prolonged measurements with a GPS receiver. There were also no differences in precision of habitat dimensions when mapped using a continuous versus a position fix average GPS data collection method. Despite there being some disadvantages to using the GPS in stream habitat studies, measuring stream habitats with a GPS resulted in spatially referenced data that allowed the assessment of relative habitat position and changes in habitats over time, and was often faster than using a tape measure. For most spatial scales of interest, the precision and accuracy of DGPS data are adequate and have logistical advantages when compared to traditional methods of measurement. ?? 2006 Springer Science+Business Media

  11. High accuracy motor controller for positioning optical filters in the CLAES Spectrometer

    NASA Technical Reports Server (NTRS)

    Thatcher, John B.

    1989-01-01

    The Etalon Drive Motor (EDM), a precision etalon control system designed for accurate positioning of etalon filters in the IR spectrometer of the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment is described. The EDM includes a brushless dc torque motor, which has an infinite resolution for setting an etalon filter to any desired angle, a four-filter etalon wheel, and an electromechanical resolver for angle information. An 18-bit control loop provides high accuracy, resolution, and stability. Dynamic computer interaction allows the user to optimize the step response. A block diagram of the motor controller is presented along with a schematic of the digital/analog converter circuit.

  12. [Positional accuracy and quality assurance of Backup JAWs required for volumetric modulated arc therapy].

    PubMed

    Tatsumi, Daisaku; Nakada, Ryosei; Ienaga, Akinori; Yomoda, Akane; Inoue, Makoto; Ichida, Takao; Hosono, Masako

    2012-01-01

    The tolerance of the Backup diaphragm (Backup JAW) setting in Elekta linac was specified as 2 mm according to the AAPM TG-142 report. However, the tolerance and the quality assurance procedure for volumetric modulated arc therapy (VMAT) was not provided. This paper describes positional accuracy and quality assurance procedure of the Backup JAWs required for VMAT. It was found that a gap-width error of the Backup JAW by a sliding window test needed to be less than 1.5 mm for prostate VMAT delivery. It was also confirmed that the gap-widths had been maintained with an error of 0.2 mm during the past one year.

  13. Accuracy improvement in peak positioning of spectrally distorted fiber Bragg grating sensors by Gaussian curve fitting

    SciTech Connect

    Lee, Hyun-Wook; Park, Hyoung-Jun; Lee, June-Ho; Song, Minho

    2007-04-20

    To improve measurement accuracy of spectrally distorted fiber Bragg grating temperature sensors, reflection profiles were curve fitted to Gaussian shapes, of which center positions were transformed into temperature information.By applying the Gaussian curve-fitting algorithm in a tunable bandpass filter demodulation scheme,{approx}0.3 deg. C temperature resolution was obtained with a severely distorted grating sensor, which was much better than that obtained using the highest peak search algorithm. A binary search was also used to retrieve the optimal fitting curves with the least amount of processing time.

  14. High accuracy integrated global positioning system/inertial navigation system LDRD: Final report

    SciTech Connect

    Owen, T.E.; Meindl, M.A.; Fellerhoff, J.R.

    1997-03-01

    This report contains the results of a Sandia National Laboratories Directed Research and Development (LDRD) program to investigate the integration of Global Positioning System (GPS) and inertial navigation system (INS) technologies toward the goal of optimizing the navigational accuracy of the combined GPSANS system. The approach undertaken is to integrate the data from an INS, which has long term drifts, but excellent short term accuracy, with GPS carrier phase signal information, which is accurate to the sub-centimeter level, but requires continuous tracking of the GPS signals. The goal is to maintain a sub-meter accurate navigation solution while the vehicle is in motion by using the GPS measurements to estimate the INS navigation errors and then using the refined INS data to aid the GPS carrier phase cycle slip detection and correction and bridge dropouts in the GPS data. The work was expanded to look at GPS-based attitude determination, using multiple GPS receivers and antennas on a single platform, as a possible navigation aid. Efforts included not only the development of data processing algorithms and software, but also the collection and analysis of GPS and INS flight data aboard a Twin Otter aircraft. Finally, the application of improved navigation system accuracy to synthetic aperture radar (SAR) target location is examined.

  15. Quality assurance of stereotactic alignment and patient positioning mechanical accuracy for robotized Gamma Knife radiosurgery.

    PubMed

    Ma, Lijun; Chiu, Joshua; Hoye, Jocelyn; McGuiness, Christopher; Perez-Andujar, Angelica

    2014-12-01

    The automatic patient positioning system and its alignment is critical and specified to be less than 0.35 mm for a radiosurgical treatment with the latest robotized Gamma Knife Perfexion (GKPFX). In this study, we developed a quantitative QA procedure to verify the accuracy and robustness of such a system. In particular, we applied the test to a unit that has performed >1000 procedures at our institution. For the test, a radiochromic film was first placed inside a spherical film phantom and then irradiated with a sequence of linearly placed shots of equal collimator size (e.g. 4 mm) via the Leksell Gamma Knife Perfexion system (PFX). The shots were positioned with either equal or unequal gaps of approximately 8 mm both at center and off-center positions of the patient positioning system. Two independent methods of localizing the irradiation shot center coordinates were employed to measure the gap spacing between adjacent shots. The measured distance was then compared with the initial preset values for the test. On average, the positioning uncertainty for the PFX delivery system was found to be 0.03 ± 0.2 mm (2σ). No significant difference in the positioning uncertainty was noted among measurements in the x-, y- and z-axis orientations. In conclusion, a simple, fast, and quantitative test was developed and demonstrated for routine QA of the submillimeter PFX patient positioning system. This test also enables independent verification of any patient-specific shot positioning for a critical treatment such as a tumor in the brainstem.

  16. Patient positioning and the accuracy of pulmonary artery pressure measurements (180f).

    PubMed

    Shih, F J

    1999-12-01

    The measurement of pulmonary artery pressure (PAP) is a common nursing practice in hemodynamic monitoring of patients in the emergency room and intensive care unit. Several researchers have proposed that PAP should be measured with the patient in a supine position with legs horizontal in order to promote a relaxed state. The most widely used reference point is the phlebostatic axis, which is located at the intersection of the fourth intercostal space and the midchest level. However, this positioning requirement is in conflict with one of the goals of nursing care, which is to achieve comfortable positioning of the patient without compromising respiratory or cardiovascular function. In addition, since frequent readings are necessary, critically ill patients can lose valuable sleep time. The existing literature still fails to justify the validity of the phlebostatic axis as an external reference point for leveling the pressure transducer. In addition, findings on the accuracy of readings obtained in the supine, Fowler's and lateral recumbent positions are also in conflict. This paper reviewed research related to measurement of PAP in the supine, various Fowler's, and lateral positions in order to clarify the major factors which might have resulted in the conflicts in data on PAP measurements. Suggestions are also provided for nurse clinicians to obtain more accurate PAP measurements. PMID:10576120

  17. Accuracy of relative positioning by interferometry with GPS Double-blind test results

    NASA Technical Reports Server (NTRS)

    Counselman, C. C., III; Gourevitch, S. A.; Herring, T. A.; King, B. W.; Shapiro, I. I.; Cappallo, R. J.; Rogers, A. E. E.; Whitney, A. R.; Greenspan, R. L.; Snyder, R. E.

    1983-01-01

    MITES (Miniature Interferometer Terminals for Earth Surveying) observations conducted on December 17 and 29, 1980, are analyzed. It is noted that the time span of the observations used on each day was 78 minutes, during which five satellites were always above 20 deg elevation. The observations are analyzed to determine the intersite position vectors by means of the algorithm described by Couselman and Gourevitch (1981). The average of the MITES results from the two days is presented. The rms differences between the two determinations of the components of the three vectors, which were about 65, 92, and 124 m long, were 8 mm for the north, 3 mm for the east, and 6 mm for the vertical. It is concluded that, at least for short distances, relative positioning by interferometry with GPS can be done reliably with subcentimeter accuracy.

  18. Position detection accuracy of a novel linac-mounted intrafractional x-ray imaging system

    SciTech Connect

    Fast, Martin F.; Krauss, Andreas; Oelfke, Uwe; Nill, Simeon

    2012-01-15

    Purpose: The authors have developed a system that monitors intrafractional target motion perpendicular to the treatment beam with the aid of radioopaque markers by means of separating kV image and megavoltage (MV) treatment field on a single flat-panel detector. Methods: They equipped a research Siemens Artiste linear accelerator (linac) with a 41 x 41 cm{sup 2} a-Si flat-panel detector underneath the treatment head. The in-line geometry allows kV (imaging) and MV (treatment) beams to share closely aligned beam axes. The kV source, usually mounted directly across from the flat-panel imager, was retracted toward the gantry by 13 cm to intentionally misalign kV and MV beams, resulting in a geometric separation of MV treatment field and kV image on the detector. Two consecutive images acquired within 140 ms (the first with MV-only and the second with kV and MV signal) were subtracted to generate a kV-only image. The images were then analyzed ''online'' with an automated threshold-based marker detection algorithm. They employed a 3D and a 4D phantom equipped with either a single radioopaque marker or three Calypso beacons to mimic respiratory motion. Measured room positions were either cross-referenced with a phantom voltage signal (single marker) or the Calypso system. The accuracy of the back-projection (from detected marker positions into room coordinates) was verified by a simulation study. Results: A phantom study has demonstrated that the imaging framework is capable of automatically detecting marker positions and sending this information to the tracking tool at an update rate of 7.14 Hz. The system latency is 86.9 {+-} 1.0 ms for single marker detection in the absence of MV radiation. In the presence of a circular MV field of 5 cm diameter, the latency is 87.1 {+-} 0.9 ms. The total RMS position detection accuracy is 0.20 mm (without MV radiation) and 0.23 mm (with MV). Conclusions: Based on the evaluated motion patterns and MV field size, the positional

  19. Effect of Traffic Position Accuracy for Conducting Safe Airport Surface Operations

    NASA Technical Reports Server (NTRS)

    Jones, Denise R.; Prinzel, Lawrence J., III; Bailey, Randall E.; Arthur, Jarvis J., III; Barnes, James R.

    2014-01-01

    The Next Generation Air Transportation System (NextGen) concept proposes many revolutionary operational concepts and technologies, such as display of traffic information and movements, airport moving maps (AMM), and proactive alerts of runway incursions and surface traffic conflicts, to deliver an overall increase in system capacity and safety. A piloted simulation study was conducted at the National Aeronautics and Space Administration (NASA) Langley Research Center to evaluate the ability to conduct safe and efficient airport surface operations while utilizing an AMM displaying traffic of various position accuracies as well as the effect of traffic position accuracy on airport conflict detection and resolution (CD&R) capability. Nominal scenarios and off-nominal conflict scenarios were conducted using 12 airline crews operating in a simulated Memphis International Airport terminal environment. The data suggest that all traffic should be shown on the airport moving map, whether qualified or unqualified, and conflict detection and resolution technologies provide significant safety benefits. Despite the presence of traffic information on the map, collisions or near collisions still occurred; when indications or alerts were generated in these same scenarios, the incidences were averted.

  20. Stimulus Probability Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Kent, Christopher; Lamberts, Koen

    2016-01-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…

  1. Single Particle-Photon Imaging Detector With 4-Dimensional Output: Absolute Time-of-hit, X-Y Position, and PHA: Applications in Space Science Instruments

    NASA Astrophysics Data System (ADS)

    Paschalidis, N. P.; Mitchell, D. G.; Brandt, P. C.

    2006-12-01

    A detector that can simultaneously measure time, position, and pulse high analysis (PHA) of single particle/photons with high resolutions and speeds, is a strong enabling technology for many space science instruments such as: energetic neutral atom imagers, low energy neutrals, energetic particle spectrometers, ion/electron plasma analyzers, UV spectrographs, mass spectrometers, laser range finding imagers, X-ray imagers. This presentation describes one such 4-dimentional detector based on micro-channel plates (MCPs), delay line anodes, and precise time of flight, and charge integration electronics for PHA. More specifically the detector includes: a) An MCP in 2-stack or Z-stack configuration for the particle/photon detection. b) Option for a thin foil or photo-cathode in front of the MCP to increase the detection efficiency of particles or photons respectively. c) Novel 1D or 2D delay line anode adaptable to almost any geometry and physical size of common instruments mentioned above. d) Fast time of flight (TOF) electronics for the absolute time of hit and the X-Y position determination. e) Fast charge integration electronics for PHA of the total charge released by the MCP. Under certain circumstances the PHA gives information about the particle mass such as for protons, He and Oxygen, cross calibrated against UV light which typically gives a single electron distribution. f) FPGA electronics for digital data acquisition and handling. e) Standard mat lab SW for data analysis and visualization in a stand alone application. The detector achieves time of hit accuracy <50ps, X-Y position resolution <20um in a field of 2048 x 2048 pixels (2048 for 1D) and adjustable speeds of: 10MHz at 256 x 256 pixels to 1MHz at 2048 x 2048 pixels. The total-charge analysis is at 10-bits. The detector can be used in its full 4D configuration such as in TOF imaging particle analyzer (i.e ENA), or in a reduced configuration such as in a UV spectrograph with X-Y position only. Typical

  2. Stimulus probability effects in absolute identification.

    PubMed

    Kent, Christopher; Lamberts, Koen

    2016-05-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record

  3. The accuracy of station positions determined from inhomogeneous laser ranging data

    NASA Astrophysics Data System (ADS)

    Kuzmicz-Cieslak, Magdalena; Schillak, Stanislaw

    The paper presents positions of 34 Satellite Laser Ranging (SLR) stations as determined in the ITRF97 system from the LAGEOS-2 laser ranging data. Three different variants of data selection were used to determine the coordinates of the stations. The calculations were performed with the use of the GEODYN II and SOLVE programs on the basis of monthly orbital arcs for 1999. The accuracy of the results for a given station strongly depends on a number and quality of observations. Preferably at least 50 of normal points per station in one month should be used for coordinates determination. The variant of orbit determination from 16 the best stations is more accurate than from all 34 stations.

  4. Exploring the Relationship between Absolute and Relative Position and Late-Life Depression: Evidence from 10 European Countries

    ERIC Educational Resources Information Center

    Ladin, Keren; Daniels, Norman; Kawachi, Ichiro

    2010-01-01

    Purpose: Socioeconomic inequality has been associated with higher levels of morbidity and mortality. This study explores the role of absolute and relative deprivation in predicting late-life depression on both individual and country levels. Design and Methods: Country- and individual-level inequality indicators were used in multivariate logistic…

  5. Openstage: A Low-Cost Motorized Microscope Stage with Sub-Micron Positioning Accuracy

    PubMed Central

    Campbell, Robert A. A.; Eifert, Robert W.; Turner, Glenn C.

    2014-01-01

    Recent progress in intracellular calcium sensors and other fluorophores has promoted the widespread adoption of functional optical imaging in the life sciences. Home-built multiphoton microscopes are easy to build, highly customizable, and cost effective. For many imaging applications a 3-axis motorized stage is critical, but commercially available motorization hardware (motorized translators, controller boxes, etc) are often very expensive. Furthermore, the firmware on commercial motor controllers cannot easily be altered and is not usually designed with a microscope stage in mind. Here we describe an open-source motorization solution that is simple to construct, yet far cheaper and more customizable than commercial offerings. The cost of the controller and motorization hardware are under $1000. Hardware costs are kept low by replacing linear actuators with high quality stepper motors. Electronics are assembled from commonly available hobby components, which are easy to work with. Here we describe assembly of the system and quantify the positioning accuracy of all three axes. We obtain positioning repeatability of the order of in X/Y and in Z. A hand-held control-pad allows the user to direct stage motion precisely over a wide range of speeds ( to ), rapidly store and return to different locations, and execute “jumps” of a fixed size. In addition, the system can be controlled from a PC serial port. Our “OpenStage” controller is sufficiently flexible that it could be used to drive other devices, such as micro-manipulators, with minimal modifications. PMID:24586468

  6. Influence of both angle and position error of pentaprism on accuracy of pentaprism scanning system

    NASA Astrophysics Data System (ADS)

    Xu, Kun; Han, Sen; Zhang, Qiyuan; Wu, Quanying

    2014-11-01

    Pentaprism scanning system has been widely used in the measurement of large flat and wavefront, based on its property that the deviated beam will have no motion in the pitch direction. But the manufacturing and position errors of pentaprisms will bring error to the measurement and so a good error analysis method is indispensable. In this paper, we propose a new method of building mathematic models of pentaprism and through which the size and angle errors of a pentaprism can be put into the model as parameters. 4 size parameters are selected to determine the size and 11 angle parameters are selected to determine the angles of a pentaprism. Yaw, Roll and Pitch are used to describe the position error of a pentaprism and an autocollimator. A pentaprism scanning system of wavefront test is simulated by ray tracing using matlab. We design a method of separating the constant from the measurement results which will improve the measurement accuracy and analyze the system error by Monte Carlo method. This method is simple, rapid, accurate and convenient for computer programming.

  7. Accuracy of Implant Position Transfer and Surface Detail Reproduction with Different Impression Materials and Techniques

    PubMed Central

    Alikhasi, Marzieh; Siadat, Hakimeh; Kharazifard, Mohammad Javad

    2015-01-01

    Objectives: The purpose of this study was to compare the accuracy of implant position transfer and surface detail reproduction using two impression techniques and materials. Materials and Methods: A metal model with two implants and three grooves of 0.25, 0.50 and 0.75 mm in depth on the flat superior surface of a die was fabricated. Ten regular-body polyether (PE) and 10 regular-body polyvinyl siloxane (PVS) impressions with square and conical transfer copings using open tray and closed tray techniques were made for each group. Impressions were poured with type IV stone, and linear and angular displacements of the replica heads were evaluated using a coordinate measuring machine (CMM). Also, accurate reproduction of the grooves was evaluated by a video measuring machine (VMM). These measurements were compared with the measurements calculated on the reference model that served as control, and the data were analyzed with two-way ANOVA and t-test at P= 0.05. Results: There was less linear displacement for PVS and less angular displacement for PE in closed-tray technique, and less linear displacement for PE in open tray technique (P<0.001). Also, the open tray technique showed less angular displacement with the use of PVS impression material. Detail reproduction accuracy was the same in all the groups (P>0.05). Conclusion: The open tray technique was more accurate using PE, and also both closed tray and open tray techniques had acceptable results with the use of PVS. The choice of impression material and technique made no significant difference in surface detail reproduction. PMID:27252761

  8. Accuracy of positioning and irradiation targeting for multiple targets in intracranial image-guided radiation therapy: a phantom study

    NASA Astrophysics Data System (ADS)

    Tominaga, Hirofumi; Araki, Fujio; Shimohigashi, Yoshinobu; Ishihara, Terunobu; Kawasaki, Keiichi; Kanetake, Nagisa; Sakata, Junichi; Iwashita, Yuki

    2014-12-01

    This study investigated the accuracy of positioning and irradiation targeting for multiple off-isocenter targets in intracranial image-guided radiation therapy (IGRT). A phantom with nine circular targets was created to evaluate both accuracies. First, the central point of the isocenter target was positioned with a combination of an ExacTrac x-ray (ETX) and a 6D couch. The positioning accuracy was determined from the deviations of coordinates of the central point in each target obtained from the kV-cone beam computed tomography (kV-CBCT) for IGRT and the planning CT. Similarly, the irradiation targeting accuracy was evaluated from the deviations of the coordinates between the central point of each target and the central point of each multi-leaf collimator (MLC) field for multiple targets. Secondly, the 6D couch was intentionally rotated together with both roll and pitch angles of 0.5° and 1° at the isocenter and similarly the deviations were evaluated. The positioning accuracy for all targets was less than 1 mm after 6D positioning corrections. The irradiation targeting accuracy was up to 1.3 mm in the anteroposterior (AP) direction for a target 87 mm away from isocenter. For the 6D couch rotations with both roll and pitch angles of 0.5° and 1°, the positioning accuracy was up to 1.0 mm and 2.3 mm in the AP direction for the target 87 mm away from the isocenter, respectively. The irradiation targeting accuracy was up to 2.1 mm and 2.6 mm in the AP direction for the target 87 mm away from the isocenter, respectively. The off-isocenter irradiation targeting accuracy became worse than the positioning accuracy. Both off-isocenter accuracies worsened in proportion to rotation angles and the distance from the isocenter to the targets. It is necessary to examine the set-up margin for off-isocenter multiple targets at each institution because irradiation targeting accuracy is peculiar to the linac machine.

  9. Absolute accuracy and sensitivity analysis of OP-FTIR retrievals of CO2, CH4 and CO over concentrations representative of "clean air" and "polluted plumes"

    NASA Astrophysics Data System (ADS)

    Smith, T. E. L.; Wooster, M. J.; Tattaris, M.; Griffith, D. W. T.

    2011-01-01

    When compared to established point-sampling methods, Open-Path Fourier Transform Infrared (OP-FTIR) spectroscopy can provide path-integrated concentrations of multiple gases simultaneously, in situ and near-continuously. The trace gas pathlength amounts can be retrieved from the measured IR spectra using a forward model coupled to a non-linear least squares fitting procedure, without requiring "background" spectral measurements unaffected by the gases of interest. However, few studies have investigated the accuracy of such retrievals for CO2, CH4 and CO, particularly across broad concentration ranges covering those characteristic of ambient to highly polluted air (e.g. from biomass burning or industrial plumes). Here we perform such an assessment using data collected by a field-portable FTIR spectrometer. The FTIR was positioned to view a fixed IR source placed at the other end of an IR-transparent cell filled with the gases of interest, whose target concentrations were varied by more than two orders of magnitude. Retrievals made using the model are complicated by absorption line pressure broadening, the effects of temperature on absorption band shape, and by convolution of the gas absorption lines and the instrument line shape (ILS). Despite this, with careful model parameterisation (i.e. the optimum wavenumber range, ILS, and assumed gas temperature and pressure for the retrieval), concentrations for all target gases were able to be retrieved to within 5%. Sensitivity to the aforementioned model inputs was also investigated. CO retrievals were shown to be most sensitive to the ILS (a function of the assumed instrument field-of-view), which is due to the narrow nature of CO absorption lines and their consequent sensitivity to convolution with the ILS. Conversely, CO2 retrievals were most sensitive to assumed atmospheric parameters, particularly gas temperature. Our findings provide confidence that FTIR-derived trace gas retrievals of CO2, CH4 and CO based on

  10. Effects of insertion speed and trocar stiffness on the accuracy of needle position for brachytherapy

    SciTech Connect

    McGill, Carl S.; Schwartz, Jonathon A.; Moore, Jason Z.; McLaughlin, Patrick W.; Shih, Albert J.

    2012-04-15

    Purpose: In prostate brachytherapy, accurate positioning of the needle tip to place radioactive seeds at its target site is critical for successful radiation treatment. During the procedure, needle deflection leads to seed misplacement and suboptimal radiation dose to cancerous cells. In practice, radiation oncologists commonly use high-speed hand needle insertion to minimize displacement of the prostate as well as the needle deflection. Effects of speed during needle insertion and stiffness of trocar (a solid rod inside the hollow cannula) on needle deflection are studied. Methods: Needle insertion experiments into phantom were performed using a 2{sup 2} factorial design (2 parameters at 2 levels), with each condition having replicates. Analysis of the deflection data included calculating the average, standard deviation, and analysis of variance (ANOVA) to find significant single and two-way interaction factors. Results: The stiffer tungsten carbide trocar is effective in reducing the average and standard deviation of needle deflection. The fast insertion speed together with the stiffer trocar generated the smallest average and standard deviation for needle deflection for almost all cases. Conclusions: The combination of stiff tungsten carbide trocar and fast needle insertion speed are important to decreasing needle deflection. The knowledge gained from this study can be used to improve the accuracy of needle insertion during brachytherapy procedures.

  11. Assessment of Completeness and Positional Accuracy of Linear Features in Volunteered Geographic Information (vgi)

    NASA Astrophysics Data System (ADS)

    Eshghi, M.; Alesheikh, A. A.

    2015-12-01

    Recent advances in spatial data collection technologies and online services dramatically increase the contribution of ordinary people to produce, share, and use geographic information. Collecting spatial data as well as disseminating them on the internet by citizens has led to a huge source of spatial data termed as Volunteered Geographic Information (VGI) by Mike Goodchild. Although, VGI has produced previously unavailable data assets, and enriched existing ones. But its quality can be highly variable and challengeable. This presents several challenges to potential end users who are concerned about the validation and the quality assurance of the data which are collected. Almost, all the existing researches are based on how to find accurate VGI data from existing VGI data which consist of a) comparing the VGI data with the accurate official data, or b) in cases that there is no access to correct data; therefore, looking for an alternative way to determine the quality of VGI data is essential, and so forth. In this paper it has been attempt to develop a useful method to reach this goal. In this process, the positional accuracy of linear feature of Iran, Tehran OSM data have been analyzed.

  12. Consonant Production Accuracy in Young Cochlear Implant Recipients: Developmental Sound Classes and Word Position Effects

    ERIC Educational Resources Information Center

    Ertmer, David J.; Kloiber, Diana True; Jung, Jongmin; Kirleis, Katie Connell; Bradford, Denise

    2012-01-01

    Purpose: To compare young cochlear implant (CI) recipients' consonant production accuracy with that of age- and gender-matched peers who were typically developing (TD). In addition to examining initial consonants, the authors compiled new data regarding the accuracy of final consonants and the order of consonant acquisition. Methods: Eleven young…

  13. Absolute accuracy and sensitivity analysis of OP-FTIR retrievals of CO2, CH4 and CO over concentrations representative of ''clean air'' and ''polluted plumes''

    NASA Astrophysics Data System (ADS)

    Smith, T. E. L.; Wooster, M. J.; Tattaris, M.; Griffith, D. W. T.

    2010-08-01

    When compared to established point-sampling methods, Open-Path Fourier Transform Infrared (OP-FTIR) spectroscopy can provide path-integrated concentrations of multiple gases simultaneously, in situ and near-continuously. Concentrations can be retrieved from the measured IR spectra using a forward model coupled to a non-linear least squares fitting procedure, without requiring ''background'' spectral measurements unaffected by the gases of interest. However, few studies have investigated the accuracy of such retrievals for CO2, CH4 and CO, particularly across a broad concentration range covering ambient to highly polluted air (e.g. from biomass burning or industrial plumes). Here we perform such an assessment using data collected by a field-portable FTIR spectrometer. The FTIR was positioned to view a fixed IR source placed at the other end of an IR-transparent cell filled with the gases of interest, whose target concentrations were varied by up to two orders of magnitude. Retrievals made using the forward model are complicated by absorption line pressure broadening, the effects of temperature on absorption band shape and by convolution of the gas absorption lines and the instrument line shape (ILS). Despite this, with optimal forward model parameterisation (i.e. the wavenumber range used in the retrieval, gas temperature, pressure and ILS), concentration retrievals for all gases were able to be made to within 5% of the true value. Sensitivity to the aforementioned model inputs was also investigated. CO retrievals were shown to be most sensitive to the ILS (a function of the assumed instrument FOV), which is due to the narrow nature of CO absorption lines and their consequent sensitivity to convolution with the ILS. Conversely, CO2 retrievals were most sensitive to assumed atmospheric parameters, particularly temperature. The analysis suggests that trace gas concentration retrieval errors can remain well below 10%, even with the uncertainties in atmospheric pressure

  14. Prism-pair interferometry by homodyne interferometers with a common light source for high-accuracy measurement of the absolute refractive index of glasses

    SciTech Connect

    Hori, Yasuaki; Hirai, Akiko; Minoshima, Kaoru

    2011-03-10

    A prism-pair interferometer comprising two homodyne interferometers with a common light source was developed for high-precision measurements of the refractive index of optical glasses with an uncertainty of the order of 10{sup -6}. The two interferometers measure changes in the optical path length in the glass sample and in air, respectively. Uncertainties in the absolute wavelength of the common light source are cancelled out by calculating a ratio between the results from the interferometers. Uncertainties in phase measurement are suppressed by a quadrature detection system. The combined standard uncertainty of the developed system is evaluated as 1.1x10{sup -6}.

  15. 3D combinational curves for accuracy and performance analysis of positive biometrics identification

    NASA Astrophysics Data System (ADS)

    Du, Yingzi; Chang, Chein-I.

    2008-06-01

    The receiver operating characteristic (ROC) curve has been widely used as an evaluation criterion to measure the accuracy of biometrics system. Unfortunately, such an ROC curve provides no indication of the optimum threshold and cost function. In this paper, two kinds of 3D combinational curves are proposed: the 3D combinational accuracy curve and the 3D combinational performance curve. The 3D combinational accuracy curve gives a balanced view of the relationships among FAR (false alarm rate), FRR (false rejection rate), threshold t, and Cost. Six 2D curves can be derived from the 3D combinational accuracy curve: the conventional 2D ROC curve, 2D curve of (FRR, t), 2D curve of (FAR, t), 2D curve of (FRR, Cost), 2D curve of (FAR, Cost), and 2D curve of ( t, Cost). The 3D combinational performance curve can be derived from the 3D combinational accuracy curve which can give a balanced view among Security, Convenience, threshold t, and Cost. The advantages of using the proposed 3D combinational curves are demonstrated by iris recognition systems where the experimental results show that the proposed 3D combinational curves can provide more comprehensive information of the system accuracy and performance.

  16. No pain no gain: The positive impact of punishment on the strategic regulation of accuracy.

    PubMed

    Arnold, Michelle M; Chisholm, Lisa M; Prike, Toby

    2016-01-01

    Previous studies have shown that punishing people through a large penalty for volunteering incorrect information typically leads them to withhold more information (metacognitive response bias), but it does not appear to influence their ability to distinguish between their own correct and incorrect answers (metacognitive accuracy discrimination). The goal of the current study was to demonstrate that punishing people for volunteering incorrect information-versus rewarding volunteering correct information-produces more effective metacognitive accuracy discrimination. All participants completed three different general-knowledge tests: a reward test (high points for correct volunteered answers), a baseline test (equal points/penalties for volunteered correct/incorrect answers) and a punishment test (high penalty for incorrect volunteered answers). Participants were significantly better at distinguishing between their own correct and incorrect answers on the punishment than reward test, which has implications for situations requiring effective accuracy monitoring. PMID:25529220

  17. No pain no gain: The positive impact of punishment on the strategic regulation of accuracy.

    PubMed

    Arnold, Michelle M; Chisholm, Lisa M; Prike, Toby

    2016-01-01

    Previous studies have shown that punishing people through a large penalty for volunteering incorrect information typically leads them to withhold more information (metacognitive response bias), but it does not appear to influence their ability to distinguish between their own correct and incorrect answers (metacognitive accuracy discrimination). The goal of the current study was to demonstrate that punishing people for volunteering incorrect information-versus rewarding volunteering correct information-produces more effective metacognitive accuracy discrimination. All participants completed three different general-knowledge tests: a reward test (high points for correct volunteered answers), a baseline test (equal points/penalties for volunteered correct/incorrect answers) and a punishment test (high penalty for incorrect volunteered answers). Participants were significantly better at distinguishing between their own correct and incorrect answers on the punishment than reward test, which has implications for situations requiring effective accuracy monitoring.

  18. Increasing shape modelling accuracy by adjusting for subject positioning: an application to the analysis of radiographic proximal femur symmetry using data from the Osteoarthritis Initiative.

    PubMed

    Lindner, C; Wallis, G A; Cootes, T F

    2014-04-01

    In total hip arthroplasty, the shape of the contra-lateral femur frequently serves as a template for preoperative planning. Previous research on contra-lateral femoral symmetry has been based on conventional hip geometric measurements (which reduce shape to a series of linear measurements) and did not take the effect of subject positioning on radiographic femur shape into account. The aim of this study was to analyse proximal femur symmetry based on statistical shape models (SSMs) which quantify global femoral shape while also adjusting for differences in subject positioning during image acquisition. We applied our recently developed fully automatic shape model matching (FASMM) system to automatically segment the proximal femur from AP pelvic radiographs to generate SSMs of the proximal femurs of 1258 Caucasian females (mean age: 61.3 SD=9.0). We used a combined SSM (capturing the left and right femurs) to identify and adjust for shape variation attributable to subject positioning as well as a single SSM (including all femurs as left femurs) to analyse proximal femur symmetry. We also calculated conventional hip geometric measurements (head diameter, neck width, shaft width and neck-shaft angle) using the output of the FASMM system. The combined SSM revealed two modes that were clearly attributable to subject positioning. The average difference (mean point-to-curve distance) between left and right femur shape was 1.0mm before and 0.8mm after adjusting for these two modes. The automatic calculation of conventional hip geometric measurements after adjustment gave an average absolute percent asymmetry of within 3.1% and an average absolute difference of within 1.1mm or 2.9° for all measurements. We conclude that (i) for Caucasian females the global shape of the right and left proximal femurs is symmetric without isolated locations of asymmetry; (ii) a combined left-right SSM can be used to adjust for radiographic shape variation due to subject positioning; and (iii

  19. Influence of GPS/GLONASS differential code biases on the determination accuracy of the absolute total electron content in the ionosphere

    NASA Astrophysics Data System (ADS)

    Yasyukevich, Yu. V.; Mylnikova, A. A.; Kunitsyn, V. E.; Padokhin, A. M.

    2015-11-01

    Systematic error arises when the total electron content (TEC) is estimated with the simultaneous use of phase and code GPS/GLONASS measurements. This is related to the different signal propagation times at L1 and L2 frequencies in the radio frequency path of the transmitting and receiving equipment, the so-called differential code biases. A differential code bias of 1 ns results in an error of ~2.9 TECU when TEC is determined. Differential code bias variations on a long time interval, which were obtained at the CODE laboratory, were analyzed. It has been found that the systematic variation in these biases and considerable seasonal variations apparently caused by the environmental state (temperature and humidity), which sometimes reach 20 TECU (in TEC units), are observed for several stations. The algorithm for determining differential code biases at an individual station and the results of correction for absolute slant TEC are also presented. Presented results show algorithm effectiveness for various geographical regions and solar activity.

  20. Positioning accuracy of cone-beam computed tomography in combination with a HexaPOD robot treatment table

    SciTech Connect

    Meyer, Juergen . E-mail: juergen.meyer@canterbury.ac.nz; Wilbert, Juergen; Baier, Kurt; Guckenberger, Matthias; Richter, Anne; Sauer, Otto; Flentje, Michael

    2007-03-15

    Purpose: To scrutinize the positioning accuracy and reproducibility of a commercial hexapod robot treatment table (HRTT) in combination with a commercial cone-beam computed tomography system for image-guided radiotherapy (IGRT). Methods and Materials: The mechanical stability of the X-ray volume imaging (XVI) system was tested in terms of reproducibility and with a focus on the moveable parts, i.e., the influence of kV panel and the source arm on the reproducibility and accuracy of both bone and gray value registration using a head-and-neck phantom. In consecutive measurements the accuracy of the HRTT for translational, rotational, and a combination of translational and rotational corrections was investigated. The operational range of the HRTT was also determined and analyzed. Results: The system performance of the XVI system alone was very stable with mean translational and rotational errors of below 0.2 mm and below 0.2{sup o}, respectively. The mean positioning accuracy of the HRTT in combination with the XVI system summarized over all measurements was below 0.3 mm and below 0.3{sup o} for translational and rotational corrections, respectively. The gray value match was more accurate than the bone match. Conclusion: The XVI image acquisition and registration procedure were highly reproducible. Both translational and rotational positioning errors can be corrected very precisely with the HRTT. The HRTT is therefore well suited to complement cone-beam computed tomography to take full advantage of position correction in six degrees of freedom for IGRT. The combination of XVI and the HRTT has the potential to improve the accuracy of high-precision treatments.

  1. Accuracy of implant positioning for minimally invasive total knee arthroplasty in patients with severe varus deformity.

    PubMed

    Niki, Yasuo; Matsumoto, Hideo; Otani, Toshiro; Enomoto, Hiroyuki; Toyama, Yoshiaki; Suda, Yasunori

    2010-04-01

    Minimally invasive surgery (MIS) in total knee arthroplasty (TKA) reportedly yields decreased patient morbidity and a rapid return of function, but how much deformity can be accepted for MIS-TKA remains unclear. This study investigated 238 knees from 218 consecutive patients who underwent MIS-TKA. Patients were divided into groups with tibiofemoral mechanical axis (TFM) 195 degrees or greater and TFM less than 195 degrees, then clinical and radiographic results were compared. Similar improvements in knee score at 3 months postoperatively were obtained in the both groups, whereas radiographic accuracy of the coronal alignment in the TFM >or=195 degrees group was inferior to that in TFM <195 degrees group. Postoperative TFM was significantly worsened in patients with lateral bowing angle of the femoral shaft (LBFS) 4 degrees or greater, and 53% of patients in the TFM >or=195 degrees group displayed LBFS 4 degrees or greater, explaining the inferior radiographic accuracy in this group compared with the TFM <195 degrees group. These results indicate that use of MIS techniques decreases radiographic accuracy, particularly in patients with severe genu varum and increased LBFS. PMID:20347714

  2. Method to quantify accuracy of position feedback signals of a three-dimensional two-photon laser-scanning microscope

    PubMed Central

    Kummer, Michael; Kirmse, Knut; Witte, Otto W.; Haueisen, Jens; Holthoff, Knut

    2015-01-01

    Two-photon laser-scanning microscopy enables to record neuronal network activity in three-dimensional space while maintaining single-cellular resolution. One of the proposed approaches combines galvanometric x-y scanning with piezo-driven objective movements and employs hardware feedback signals for position monitoring. However, readily applicable methods to quantify the accuracy of those feedback signals are currently lacking. Here we provide techniques based on contact-free laser reflection and laser triangulation for the quantification of positioning accuracy of each spatial axis. We found that the lateral feedback signals are sufficiently accurate (defined as <2.5 µm) for a wide range of scan trajectories and frequencies. We further show that axial positioning accuracy does not only depend on objective acceleration and mass but also its geometry. We conclude that the introduced methods allow a reliable quantification of position feedback signals in a cost-efficient, easy-to-install manner and should be applicable for a wide range of two-photon laser scanning microscopes. PMID:26504620

  3. Method to quantify accuracy of position feedback signals of a three-dimensional two-photon laser-scanning microscope.

    PubMed

    Kummer, Michael; Kirmse, Knut; Witte, Otto W; Haueisen, Jens; Holthoff, Knut

    2015-10-01

    Two-photon laser-scanning microscopy enables to record neuronal network activity in three-dimensional space while maintaining single-cellular resolution. One of the proposed approaches combines galvanometric x-y scanning with piezo-driven objective movements and employs hardware feedback signals for position monitoring. However, readily applicable methods to quantify the accuracy of those feedback signals are currently lacking. Here we provide techniques based on contact-free laser reflection and laser triangulation for the quantification of positioning accuracy of each spatial axis. We found that the lateral feedback signals are sufficiently accurate (defined as <2.5 µm) for a wide range of scan trajectories and frequencies. We further show that axial positioning accuracy does not only depend on objective acceleration and mass but also its geometry. We conclude that the introduced methods allow a reliable quantification of position feedback signals in a cost-efficient, easy-to-install manner and should be applicable for a wide range of two-photon laser scanning microscopes. PMID:26504620

  4. SU-E-J-118: Verification of Intrafractional Positional Accuracy Using Ultrasound Autoscan Tracking for Prostate Cancer Treatment

    SciTech Connect

    Yu, S; Hristov, D; Phillips, T

    2014-06-01

    Purpose: Transperineal ultrasound imaging is attractive option for imageguided radiation therapy as there is no need to implant fiducials, no extra imaging dose, and real time continuous imaging is possible during treatment. The aim of this study is to verify the tracking accuracy of a commercial ultrasound system under treatment conditions with a male pelvic phantom. Methods: A CT and ultrasound scan were acquired for the male pelvic phantom. The phantom was then placed in a treatment mimicking position on a motion platform. The axial and lateral tracking accuracy of the ultrasound system were verified using an independent optical tracking system. The tracking accuracy was evaluated by tracking the phantom position detected by the ultrasound system, and comparing it to the optical tracking system under the conditions of beam on (15 MV), beam off, poor image quality with an acoustic shadow introduced, and different phantom motion cycles (10 and 20 second periods). Additionally, the time lag between the ultrasound-detected and actual phantom motion was investigated. Results: Displacement amplitudes reported by the ultrasound system and optical system were within 0.5 mm of each other for both directions and all conditions. The ultrasound tracking performance in axial direction was better than in lateral direction. Radiation did not interfere with ultrasound tracking while image quality affected tracking accuracy. The tracking accuracy was better for periodic motion with 20 second period. The time delay between the ultrasound tracking system and the phantom motion was clinically acceptable. Conclusion: Intrafractional prostate motion is a potential source of treatment error especially in the context of emerging SBRT regimens. It is feasible to use transperineal ultrasound daily to monitor prostate motion during treatment. Our results verify the tracking accuracy of a commercial ultrasound system to be better than 1 mm under typical external beam treatment conditions.

  5. Two-probe optical encoder for absolute positioning of precision stages by using an improved scale grating.

    PubMed

    Li, Xinghui; Wang, Huanhuan; Ni, Kai; Zhou, Qian; Mao, Xinyu; Zeng, Lijiang; Wang, Xiaohao; Xiao, Xiang

    2016-09-19

    In this paper, a novel optical encoder enabling the simultaneous measurement of displacement and the position of precision stages is presented. The encoder is composed of an improved single-track scale grating and a compact two-probe reading head. In the scale grating, multiple reference codes are physically superimposed onto the incremental grooves, in contrast to conventional designs, where an additional track is necessary. The distribution of the reference codes follows a specific mathematical algorithm. For the reading head, a two-probe structure is designed to identify the discrete reference codes by means of the superimposition of the codes with a stationary mask and to read the continuous incremental grooves by means of a grating interferometry, respectively. A prototype encoder was designed, constructed and evaluated, and experimental results show that the distance code precision achieved is 0.5 μm, while the linearity error of the linear displacement measurement is less than 0.06%. PMID:27661879

  6. Accuracy of an UWB-based position tracking system used for time-motion analyses in game sports.

    PubMed

    Leser, Roland; Schleindlhuber, Armin; Lyons, Keith; Baca, Arnold

    2014-01-01

    The main aim of this study was to determine the accuracy of the ultra-wideband (UWB)-based positioning system Ubisense, which is used for time-motion analysis in sports. Furthermore, some alternatives for positioning the system's transponders on the atheletes, as well as the accuracy depending on the location of measurement, were tested. Therefore, in a pre-study, some basic issues were examined (measurement assumptions and consistency and location of the system's transponder used for position detection), and position measurements at the borders and in the centre of a basketball field were performed. In the main study, 13 male basketball players (15.8 years ± 0.6; 187.9 height ± 3.4; 77.5 weight ± 3.7), equipped with a Ubisense transponder mounted on top of their heads, handled a trundle wheel during simulated match play. The players with the trundle wheel participated passively in the match by following one of the ten competing players. The distance measurements of the trundle wheel were used as reference values and compared to the Ubisense distance estimations. Best results were found with the measurements of a single mounted transponder on top of the athlete's heads. No differences were detectable in the accuracy between measurements in the centre and at the borders of the basketball field. The (Ubisense) system's difference to the (trundle wheel) reference was 3.45 ± 1.99%, resulting in 95% limits of agreement of -0.46-7.35%. The study indicates the examined system's sufficient accuracy for time-motion analysis in basketball. PMID:24512176

  7. Accuracy of an UWB-based position tracking system used for time-motion analyses in game sports.

    PubMed

    Leser, Roland; Schleindlhuber, Armin; Lyons, Keith; Baca, Arnold

    2014-01-01

    The main aim of this study was to determine the accuracy of the ultra-wideband (UWB)-based positioning system Ubisense, which is used for time-motion analysis in sports. Furthermore, some alternatives for positioning the system's transponders on the atheletes, as well as the accuracy depending on the location of measurement, were tested. Therefore, in a pre-study, some basic issues were examined (measurement assumptions and consistency and location of the system's transponder used for position detection), and position measurements at the borders and in the centre of a basketball field were performed. In the main study, 13 male basketball players (15.8 years ± 0.6; 187.9 height ± 3.4; 77.5 weight ± 3.7), equipped with a Ubisense transponder mounted on top of their heads, handled a trundle wheel during simulated match play. The players with the trundle wheel participated passively in the match by following one of the ten competing players. The distance measurements of the trundle wheel were used as reference values and compared to the Ubisense distance estimations. Best results were found with the measurements of a single mounted transponder on top of the athlete's heads. No differences were detectable in the accuracy between measurements in the centre and at the borders of the basketball field. The (Ubisense) system's difference to the (trundle wheel) reference was 3.45 ± 1.99%, resulting in 95% limits of agreement of -0.46-7.35%. The study indicates the examined system's sufficient accuracy for time-motion analysis in basketball.

  8. Examination of the Position Accuracy of Implant Abutments Reproduced by Intra-Oral Optical Impression

    PubMed Central

    Odaira, Chikayuki; Kobayashi, Takuya; Kondo, Hisatomo

    2016-01-01

    An impression technique called optical impression using intraoral scanner has attracted attention in digital dentistry. This study aimed to evaluate the accuracy of the optical impression, comparing a virtual model reproduced by an intraoral scanner to a working cast made by conventional silicone impression technique. Two implants were placed on a master model. Working casts made of plaster were fabricated from the master model by silicone impression. The distance between the ball abutments and the angulation between the healing abutments of 5 mm and 7 mm height at master model were measured using Computer Numerical Control Coordinate Measuring Machine (CNCCMM) as control. Working casts were then measured using CNCCMM, and virtual models via stereo lithography data of master model were measured by a three-dimensional analyzing software. The distance between ball abutments of the master model was 9634.9 ± 1.2 μm. The mean values of trueness of the Lava COS and working casts were 64.5 μm and 22.5 μm, respectively, greater than that of control. The mean of precision values of the Lava COS and working casts were 15.6 μm and 13.5 μm, respectively. In the case of a 5-mm-height healing abutment, mean angulation error of the Lava COS was greater than that of the working cast, resulting in significant differences in trueness and precision. However, in the case of a 7-mm-height abutment, mean angulation errors of the Lava COS and the working cast were not significantly different in trueness and precision. Therefore, distance errors of the optical impression were slightly greater than those of conventional impression. Moreover, the trueness and precision of angulation error could be improved in the optical impression using longer healing abutments. In the near future, the development of information technology could enable improvement in the accuracy of the optical impression with intraoral scanners. PMID:27706225

  9. Automaticity and eyewitness accuracy: a 10- to 12-second rule for distinguishing accurate from inaccurate positive identifications.

    PubMed

    Dunning, David; Perretta, Scott

    2002-10-01

    Eyewitness researchers have shown that witnesses accurately choosing the culprit out of a lineup reach their decisions more quickly than those erroneously choosing an innocent individual. However, this research is silent regarding how quickly or slowly witnesses must be, in absolute terms, to indicate that they are accurate or inaccurate. Across 4 studies, the authors discovered that a time boundary of roughly 10 to 12 s best differentiated accurate from inaccurate positive identifications. Witnesses making their identification faster than 10 to 12 s were nearly 90% accurate; those taking longer were roughly 50% accurate. This finding is consistent with previous research showing that accurate witnesses are more likely than inaccurate witnesses to reach their decisions automatically, that is, quickly, without conscious thought or effort. PMID:12395819

  10. Frontal sinus accuracy in identification as measured by false positives in kin groups.

    PubMed

    Cameriere, Roberto; Ferrante, Luigi; Molleson, Theya; Brown, Barry

    2008-11-01

    The aims of this study were to verify if frontal sinuses can uniquely identify individuals belonging to family groups using Cameriere methods and to test if kinship can affect the proportion of erroneous identifications. For this purpose, we compared the proportion of false-positive identifications in a sample of 99 individuals within 20 families with a control sample of 98 other individuals without kinship. The results show that the combined use of SOR and the Yoshino code number allows personal identification with a small probability of false positives (p < 10(-6)), even when kinship is taken into account. The present research confirms the importance of studying anthropological frameworks for identification, which leads to reliable methods and allows for both quick and economic procedures.

  11. Combined Use of Absolute and Differential Seismic Arrival Time Data to Improve Absolute Event Location

    NASA Astrophysics Data System (ADS)

    Myers, S.; Johannesson, G.

    2012-12-01

    Arrival time measurements based on waveform cross correlation are becoming more common as advanced signal processing methods are applied to seismic data archives and real-time data streams. Waveform correlation can precisely measure the time difference between the arrival of two phases, and differential time data can be used to constrain relative location of events. Absolute locations are needed for many applications, which generally requires the use of absolute time data. Current methods for measuring absolute time data are approximately two orders of magnitude less precise than differential time measurements. To exploit the strengths of both absolute and differential time data, we extend our multiple-event location method Bayesloc, which previously used absolute time data only, to include the use of differential time measurements that are based on waveform cross correlation. Fundamentally, Bayesloc is a formulation of the joint probability over all parameters comprising the multiple event location system. The Markov-Chain Monte Carlo method is used to sample from the joint probability distribution given arrival data sets. The differential time component of Bayesloc includes scaling a stochastic estimate of differential time measurement precision based the waveform correlation coefficient for each datum. For a regional-distance synthetic data set with absolute and differential time measurement error of 0.25 seconds and 0.01 second, respectively, epicenter location accuracy is improved from and average of 1.05 km when solely absolute time data are used to 0.28 km when absolute and differential time data are used jointly (73% improvement). The improvement in absolute location accuracy is the result of conditionally limiting absolute location probability regions based on the precise relative position with respect to neighboring events. Bayesloc estimates of data precision are found to be accurate for the synthetic test, with absolute and differential time measurement

  12. An investigation of airborne GPS/INS for high accuracy position and velocity determination

    SciTech Connect

    Sun, H.; Cannon, M.E.; Owen, T.E.; Meindl, M.A.

    1993-12-31

    An airborne test using a differential GPS-INS system in a Twin Otter was conducted by Sandia National Laboratories to assess the feasibility of using the integrated system for cm-level position and cm/s velocity. The INS is a miniaturized ring-laser gyro IMU jointly developed by Sandia and Honeywell while the GPS system consists of the NovAtel GPSCard{trademark}. INS position, velocity and attitude data were computed using Sandia`s SANDAC flight computer system and logged at 4 Hz and GPS data was acquired at a 1 Hz rate. The mission was approximately 2.5 hours in duration and the aircraft reached separations of up to 19 km from the base station. The data was post-processed using a centralized Kalman filter approach in which the double differenced carrier phase measurements are used to update the INS data. The INS position is in turn used to detect and correct GPS carrier phase cycle slips and also to bridge GPS outages. Results are presented for the GPS-only case and also for integrated GPS/INS.

  13. Implementation of a program for quality assurance on leaf positioning accuracy using Gafchromic® RTQA2 films

    PubMed Central

    Girardi, Andrea; Anglesio, Silvia; Amadore, Gianluca; Trevisiol, Edoardo; Redda, Maria Grazia Ruo

    2014-01-01

    In radiotherapy treatments the correct dose delivery to the target volume and the consequent conservation of healthy tissues is affected by multileaf collimator (MLC) leaf positioning accuracy and reproducibility, mostly in intensity-modulated radiation therapy (IMRT): For this reason a quality assurance (QA) program is necessary to ensure the best treatment possible to each patient. The aim of this study is the implementation of a method using Gafchromic® RTQA 2 films to perform routine QA on the MLC, both for qualitative and quantitative analysis. A flatbed document scanner (Epson 10000XL) was used in conjunction with radiochromic detector; a scanning protocol was firstly defined to improve readout accuracy. RTQA2 films were irradiated with 6 MV X-rays at different dose levels to obtain calibration curve. To evaluate the leaf positioning accuracy in different conditions, a rhomboidal shape and a field consisting in three rectangular segments were selected. The images quantitative analysis was handled with a program developed in MATLAB to evaluate the differences between expected and measured leaves positions. The reproducibility and global uncertainty of the method were estimated to be equal to 0.5% and 0.6 mm, respectively. Moreover, a qualitative test was performed: A garden picket fence field, consisting in multiple segments 2 × 22 cm2, was realized setting known leaves shifts to test the method sensitivity. The picket fence test shows that the method is able to detect displacements equal to 1 mm. The results suggest that Gafchromic® RTQA2 films represent a reliable tool to perform MLC routine QA. PMID:24872610

  14. Accuracy of navigation-assisted acetabular component positioning studied by computed tomography measurements: methods and results.

    PubMed

    Ybinger, Thomas; Kumpan, W; Hoffart, H E; Muschalik, B; Bullmann, W; Zweymüller, K

    2007-09-01

    The postoperative position of the acetabular component is key for the outcome of total hip arthroplasty. Various aids have been developed to support the surgeon during implant placement. In a prospective study involving 4 centers, the computer-recorded cup alignment of 37 hip systems at the end of navigation-assisted surgery was compared with the cup angles measured on postoperative computerized tomograms. This comparison showed an average difference of 3.5 degrees (SD, 4.4 degrees ) for inclination and 6.5 degrees (SD, 7.3 degrees ) for anteversion angles. The differences in inclination correlated with the thickness of the soft tissue overlying the anterior superior iliac spine (r = 0.44; P = .007), whereas the differences in anteversion showed a correlation with the thickness of the soft tissue overlying the pubic tubercles (r = 0.52; P = .001). In centers experienced in the use of navigational tools, deviations were smaller than in units with little experience in their use. PMID:17826270

  15. An accuracy assessment of different rigid body image registration methods and robotic couch positional corrections using a novel phantom

    SciTech Connect

    Arumugam, Sankar; Xing Aitang; Jameson, Michael G.; Holloway, Lois

    2013-03-15

    Purpose: Image guided radiotherapy (IGRT) using cone beam computed tomography (CBCT) images greatly reduces interfractional patient positional uncertainties. An understanding of uncertainties in the IGRT process itself is essential to ensure appropriate use of this technology. The purpose of this study was to develop a phantom capable of assessing the accuracy of IGRT hardware and software including a 6 degrees of freedom patient positioning system and to investigate the accuracy of the Elekta XVI system in combination with the HexaPOD robotic treatment couch top. Methods: The constructed phantom enabled verification of the three automatic rigid body registrations (gray value, bone, seed) available in the Elekta XVI software and includes an adjustable mount that introduces known rotational offsets to the phantom from its reference position. Repeated positioning of the phantom was undertaken to assess phantom rotational accuracy. Using this phantom the accuracy of the XVI registration algorithms was assessed considering CBCT hardware factors and image resolution together with the residual error in the overall image guidance process when positional corrections were performed through the HexaPOD couch system. Results: The phantom positioning was found to be within 0.04 ({sigma}= 0.12) Degree-Sign , 0.02 ({sigma}= 0.13) Degree-Sign , and -0.03 ({sigma}= 0.06) Degree-Sign in X, Y, and Z directions, respectively, enabling assessment of IGRT with a 6 degrees of freedom patient positioning system. The gray value registration algorithm showed the least error in calculated offsets with maximum mean difference of -0.2({sigma}= 0.4) mm in translational and -0.1({sigma}= 0.1) Degree-Sign in rotational directions for all image resolutions. Bone and seed registration were found to be sensitive to CBCT image resolution. Seed registration was found to be most sensitive demonstrating a maximum mean error of -0.3({sigma}= 0.9) mm and -1.4({sigma}= 1.7) Degree-Sign in translational

  16. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  17. Accuracy of positioning the cervical spine for radiation therapy and the relationship to GTV, CTV and PTV.

    PubMed

    Kippenes, Hege; Gavin, Patrick R; Sande, Ronald D; Rogers, Dennis; Sweet, Vaughn

    2003-01-01

    The purpose of the study was to evaluate the accuracy and precision of a rigid positioning device for repositioning the cervical spine accurately and precisely during conformal radiation therapy of dogs. Fifteen purpose bred research dogs in a radiation therapy study were included. The dogs were positioned using a head holder and a deflatable pillow attached to the treatment table. Port films were reviewed retrospectively, and repositioning precision was recorded by measurements in three orthogonal planes of the head, 2nd cervical vertebra and 1st thoracic spinous process. Mean treatment position was compared to the planning position for a measurement of systematic set-up error. Mean interfraction position variation of the 2nd cervical vertebra was 0.2, 0.1 and 0.2 cm for the ventrodorsal, caudocranial and laterolateral directions respectively, and the average systematic set up error was 0.2, 0.1 and 0.2 cm for the ventrodorsal, caudocranial and laterolateral directions respectively. Knowledge of the magnitude of reposition errors should be included when determining the margins around the tumor. PMID:14703256

  18. Ultrasound indoor positioning system based on a low-power wireless sensor network providing sub-centimeter accuracy.

    PubMed

    Medina, Carlos; Segura, José Carlos; De la Torre, Ángel

    2013-01-01

    This paper describes the TELIAMADE system, a new indoor positioning system based on time-of-flight (TOF) of ultrasonic signal to estimate the distance between a receiver node and a transmitter node. TELIAMADE system consists of a set of wireless nodes equipped with a radio module for communication and a module for the transmission and reception of ultrasound. The access to the ultrasonic channel is managed by applying a synchronization algorithm based on a time-division multiplexing (TDMA) scheme. The ultrasonic signal is transmitted using a carrier frequency of 40 kHz and the TOF measurement is estimated by applying a quadrature detector to the signal obtained at the A/D converter output. Low sampling frequencies of 17.78 kHz or even 12.31 kHz are possible using quadrature sampling in order to optimize memory requirements and to reduce the computational cost in signal processing. The distance is calculated from the TOF taking into account the speed of sound. An excellent accuracy in the estimation of the TOF is achieved using parabolic interpolation to detect of maximum of the signal envelope at the matched filter output. The signal phase information is also used for enhancing the TOF measurement accuracy. Experimental results show a root mean square error (rmse) less than 2 mm and a standard deviation less than 0.3 mm for pseudorange measurements in the range of distances between 2 and 6 m. The system location accuracy is also evaluated by applying multilateration. A sub-centimeter location accuracy is achieved with an average rmse of 9.6 mm. PMID:23486218

  19. Ultrasound Indoor Positioning System Based on a Low-Power Wireless Sensor Network Providing Sub-Centimeter Accuracy

    PubMed Central

    Medina, Carlos; Segura, José Carlos; De la Torre, Ángel

    2013-01-01

    This paper describes the TELIAMADE system, a new indoor positioning system based on time-of-flight (TOF) of ultrasonic signal to estimate the distance between a receiver node and a transmitter node. TELIAMADE system consists of a set of wireless nodes equipped with a radio module for communication and a module for the transmission and reception of ultrasound. The access to the ultrasonic channel is managed by applying a synchronization algorithm based on a time-division multiplexing (TDMA) scheme. The ultrasonic signal is transmitted using a carrier frequency of 40 kHz and the TOF measurement is estimated by applying a quadrature detector to the signal obtained at the A/D converter output. Low sampling frequencies of 17.78 kHz or even 12.31 kHz are possible using quadrature sampling in order to optimize memory requirements and to reduce the computational cost in signal processing. The distance is calculated from the TOF taking into account the speed of sound. An excellent accuracy in the estimation of the TOF is achieved using parabolic interpolation to detect of maximum of the signal envelope at the matched filter output. The signal phase information is also used for enhancing the TOF measurement accuracy. Experimental results show a root mean square error (rmse) less than 2 mm and a standard deviation less than 0.3 mm for pseudorange measurements in the range of distances between 2 and 6 m. The system location accuracy is also evaluated by applying multilateration. A sub-centimeter location accuracy is achieved with an average rmse of 9.6 mm. PMID:23486218

  20. Precision goniometer equipped with a 22-bit absolute rotary encoder.

    PubMed

    Xiaowei, Z; Ando, M; Jidong, W

    1998-05-01

    The calibration of a compact precision goniometer equipped with a 22-bit absolute rotary encoder is presented. The goniometer is a modified Huber 410 goniometer: the diffraction angles can be coarsely generated by a stepping-motor-driven worm gear and precisely interpolated by a piezoactuator-driven tangent arm. The angular accuracy of the precision rotary stage was evaluated with an autocollimator. It was shown that the deviation from circularity of the rolling bearing utilized in the precision rotary stage restricts the angular positioning accuracy of the goniometer, and results in an angular accuracy ten times larger than the angular resolution of 0.01 arcsec. The 22-bit encoder was calibrated by an incremental rotary encoder. It became evident that the accuracy of the absolute encoder is approximately 18 bit due to systematic errors.

  1. High-Accuracy Self-Calibration for Smart, Optical Orbiting Payloads Integrated with Attitude and Position Determination.

    PubMed

    Li, Jin; Xing, Fei; Chu, Daping; Liu, Zilong

    2016-01-01

    A high-accuracy space smart payload integrated with attitude and position (SSPIAP) is a new type of optical remote sensor that can autonomously complete image positioning. Inner orientation parameters (IOPs) are a prerequisite for image position determination of an SSPIAP. The calibration of IOPs significantly influences the precision of image position determination of SSPIAPs. IOPs can be precisely measured and calibrated in a laboratory. However, they may drift to a significant degree because of vibrations during complicated launches and on-orbit functioning. Therefore, laboratory calibration methods are not suitable for on-orbit functioning. We propose an on-orbit self-calibration method for SSPIAPs. Our method is based on an auto-collimating dichroic filter combined with a micro-electro-mechanical system (MEMS) point-source focal plane. A MEMS procedure is used to manufacture a light transceiver focal plane, which integrates with point light sources and a complementary metal oxide semiconductor (CMOS) sensor. A dichroic filter is used to fabricate an auto-collimation light reflection element. The dichroic filter and the MEMS point light sources focal plane are integrated into an SSPIAP so it can perform integrated self-calibration. Experiments show that our method can achieve micrometer-level precision, which is good enough to complete real-time calibration without temporal or spatial limitations. PMID:27472339

  2. High-Accuracy Self-Calibration for Smart, Optical Orbiting Payloads Integrated with Attitude and Position Determination

    PubMed Central

    Li, Jin; Xing, Fei; Chu, Daping; Liu, Zilong

    2016-01-01

    A high-accuracy space smart payload integrated with attitude and position (SSPIAP) is a new type of optical remote sensor that can autonomously complete image positioning. Inner orientation parameters (IOPs) are a prerequisite for image position determination of an SSPIAP. The calibration of IOPs significantly influences the precision of image position determination of SSPIAPs. IOPs can be precisely measured and calibrated in a laboratory. However, they may drift to a significant degree because of vibrations during complicated launches and on-orbit functioning. Therefore, laboratory calibration methods are not suitable for on-orbit functioning. We propose an on-orbit self-calibration method for SSPIAPs. Our method is based on an auto-collimating dichroic filter combined with a micro-electro-mechanical system (MEMS) point-source focal plane. A MEMS procedure is used to manufacture a light transceiver focal plane, which integrates with point light sources and a complementary metal oxide semiconductor (CMOS) sensor. A dichroic filter is used to fabricate an auto-collimation light reflection element. The dichroic filter and the MEMS point light sources focal plane are integrated into an SSPIAP so it can perform integrated self-calibration. Experiments show that our method can achieve micrometer-level precision, which is good enough to complete real-time calibration without temporal or spatial limitations. PMID:27472339

  3. High-Accuracy Self-Calibration for Smart, Optical Orbiting Payloads Integrated with Attitude and Position Determination.

    PubMed

    Li, Jin; Xing, Fei; Chu, Daping; Liu, Zilong

    2016-01-01

    A high-accuracy space smart payload integrated with attitude and position (SSPIAP) is a new type of optical remote sensor that can autonomously complete image positioning. Inner orientation parameters (IOPs) are a prerequisite for image position determination of an SSPIAP. The calibration of IOPs significantly influences the precision of image position determination of SSPIAPs. IOPs can be precisely measured and calibrated in a laboratory. However, they may drift to a significant degree because of vibrations during complicated launches and on-orbit functioning. Therefore, laboratory calibration methods are not suitable for on-orbit functioning. We propose an on-orbit self-calibration method for SSPIAPs. Our method is based on an auto-collimating dichroic filter combined with a micro-electro-mechanical system (MEMS) point-source focal plane. A MEMS procedure is used to manufacture a light transceiver focal plane, which integrates with point light sources and a complementary metal oxide semiconductor (CMOS) sensor. A dichroic filter is used to fabricate an auto-collimation light reflection element. The dichroic filter and the MEMS point light sources focal plane are integrated into an SSPIAP so it can perform integrated self-calibration. Experiments show that our method can achieve micrometer-level precision, which is good enough to complete real-time calibration without temporal or spatial limitations.

  4. Evaluation of MLC leaf positioning accuracy for static and dynamic IMRT treatments using DAVID in vivo dosimetric system.

    PubMed

    Karagoz, Gulay; Zorlu, Faruk; Yeginer, Mete; Yildiz, Demet; Ozyigit, Gokhan

    2016-01-01

    Accuracy and precision of leaf positioning in multileaf collimators (MLCs) are significant factors for the accuracy of IMRT treatments. This study aimed to inves-tigate the accuracy and repeatability of the MLC leaf positioning via the DAVID invivo dosimetric system for dynamic and static MLC systems. The DAVID system was designed as multiwire transmission ionization chamber which is placed in accessory holder of linear accelerators. Each wire of DAVID system corresponds to a MLC leaf-pair to verify the leaf positioning accuracy during IMRT treatment and QA. In this study, verifications of IMRT plans of five head and neck (H&N) and five prostate patients treated in a Varian DHX linear accelerator with 80-leaf MLC were performed using DAVID system. Before DAVID-based dosimetry, Electronics Portal Imaging Device (EPID) and PTW 2D ARRAY dosimetry system were used for 2D verification of each plan. The measurements taken by DAVID system in the first day of the treatments were used as reference for the following measurements taken over the next four weeks. The deviations in leaf positioning were evaluated by "Total Deviation (TD)" parameter calculated by DAVID software. The delivered IMRT plans were originally prepared using dynamic MLC method. The same plans were subsequently calculated based on static MLC method with three different intensity levels of five (IL5), 10 (IL10) and 20 (IL20) in order to compare the performances of MLC leaf positioning repeatability for dynamic and static IMRT plans. The leaf positioning accuracy is also evaluated by analyzing DynaLog files based on error histograms and root mean square (RMS) errors of leaf pairs' positions. Moreover, a correlation analysis between simultaneously taken DAVID and EPID measurements and DynaLog file recordings was subsequently performed. In the analysis of DAVID outputs, the overall deviations of dynamic MLC-based IMRT calculated from the deviations of the four weeks were found as 0.55% ± 0.57% and 1.48% ± 0

  5. Evaluation of MLC leaf positioning accuracy for static and dynamic IMRT treatments using DAVID in vivo dosimetric system.

    PubMed

    Karagoz, Gulay; Zorlu, Faruk; Yeginer, Mete; Yildiz, Demet; Ozyigit, Gokhan

    2016-03-08

    Accuracy and precision of leaf positioning in multileaf collimators (MLCs) are significant factors for the accuracy of IMRT treatments. This study aimed to inves-tigate the accuracy and repeatability of the MLC leaf positioning via the DAVID invivo dosimetric system for dynamic and static MLC systems. The DAVID system was designed as multiwire transmission ionization chamber which is placed in accessory holder of linear accelerators. Each wire of DAVID system corresponds to a MLC leaf-pair to verify the leaf positioning accuracy during IMRT treatment and QA. In this study, verifications of IMRT plans of five head and neck (H&N) and five prostate patients treated in a Varian DHX linear accelerator with 80-leaf MLC were performed using DAVID system. Before DAVID-based dosimetry, Electronics Portal Imaging Device (EPID) and PTW 2D ARRAY dosimetry system were used for 2D verification of each plan. The measurements taken by DAVID system in the first day of the treatments were used as reference for the following measurements taken over the next four weeks. The deviations in leaf positioning were evaluated by "Total Deviation (TD)" parameter calculated by DAVID software. The delivered IMRT plans were originally prepared using dynamic MLC method. The same plans were subsequently calculated based on static MLC method with three different intensity levels of five (IL5), 10 (IL10) and 20 (IL20) in order to compare the performances of MLC leaf positioning repeatability for dynamic and static IMRT plans. The leaf positioning accuracy is also evaluated by analyzing DynaLog files based on error histograms and root mean square (RMS) errors of leaf pairs' positions. Moreover, a correlation analysis between simultaneously taken DAVID and EPID measurements and DynaLog file recordings was subsequently performed. In the analysis of DAVID outputs, the overall deviations of dynamic MLC-based IMRT calculated from the deviations of the four weeks were found as 0.55% ± 0.57% and 1.48% ± 0

  6. Optimization of the Coverage and Accuracy of an Indoor Positioning System with a Variable Number of Sensors.

    PubMed

    Domingo-Perez, Francisco; Lazaro-Galilea, Jose Luis; Bravo, Ignacio; Gardel, Alfredo; Rodriguez, David

    2016-06-22

    This paper focuses on optimal sensor deployment for indoor localization with a multi-objective evolutionary algorithm. Our goal is to obtain an algorithm to deploy sensors taking the number of sensors, accuracy and coverage into account. Contrary to most works in the literature, we consider the presence of obstacles in the region of interest (ROI) that can cause occlusions between the target and some sensors. In addition, we aim to obtain all of the Pareto optimal solutions regarding the number of sensors, coverage and accuracy. To deal with a variable number of sensors, we add speciation and structural mutations to the well-known non-dominated sorting genetic algorithm (NSGA-II). Speciation allows one to keep the evolution of sensor sets under control and to apply genetic operators to them so that they compete with other sets of the same size. We show some case studies of the sensor placement of an infrared range-difference indoor positioning system with a fairly complex model of the error of the measurements. The results obtained by our algorithm are compared to sensor placement patterns obtained with random deployment to highlight the relevance of using such a deployment algorithm.

  7. Optimization of the Coverage and Accuracy of an Indoor Positioning System with a Variable Number of Sensors

    PubMed Central

    Domingo-Perez, Francisco; Lazaro-Galilea, Jose Luis; Bravo, Ignacio; Gardel, Alfredo; Rodriguez, David

    2016-01-01

    This paper focuses on optimal sensor deployment for indoor localization with a multi-objective evolutionary algorithm. Our goal is to obtain an algorithm to deploy sensors taking the number of sensors, accuracy and coverage into account. Contrary to most works in the literature, we consider the presence of obstacles in the region of interest (ROI) that can cause occlusions between the target and some sensors. In addition, we aim to obtain all of the Pareto optimal solutions regarding the number of sensors, coverage and accuracy. To deal with a variable number of sensors, we add speciation and structural mutations to the well-known non-dominated sorting genetic algorithm (NSGA-II). Speciation allows one to keep the evolution of sensor sets under control and to apply genetic operators to them so that they compete with other sets of the same size. We show some case studies of the sensor placement of an infrared range-difference indoor positioning system with a fairly complex model of the error of the measurements. The results obtained by our algorithm are compared to sensor placement patterns obtained with random deployment to highlight the relevance of using such a deployment algorithm. PMID:27338414

  8. Pitfalls at the root of facial assessment on photographs: a quantitative study of accuracy in positioning facial landmarks.

    PubMed

    Cummaudo, M; Guerzoni, M; Marasciuolo, L; Gibelli, D; Cigada, A; Obertovà, Z; Ratnayake, M; Poppa, P; Gabriel, P; Ritz-Timme, S; Cattaneo, C

    2013-05-01

    In the last years, facial analysis has gained great interest also for forensic anthropology. The application of facial landmarks may bring about relevant advantages for the analysis of 2D images by measuring distances and extracting quantitative indices. However, this is a complex task which depends upon the variability in positioning facial landmarks. In addition, literature provides only general indications concerning the reliability in positioning facial landmarks on photographic material, and no study is available concerning the specific errors which may be encountered in such an operation. The aim of this study is to analyze the inter- and intra-observer error in defining facial landmarks on photographs by using a software specifically developed for this purpose. Twenty-four operators were requested to define 22 facial landmarks on frontal view photographs and 11 on lateral view images; in addition, three operators repeated the procedure on the same photographs 20 times (at distance of 24 h). In the frontal view, the landmarks with less dispersion were the pupil, cheilion, endocanthion, and stomion (sto), and the landmarks with the highest dispersion were gonion, zygion, frontotemporale, tragion, and selion (se). In the lateral view, the landmarks with the least dispersion were se, pronasale, subnasale, and sto, whereas landmarks with the highest dispersion were gnathion, pogonion, and tragion. Results confirm that few anatomical points can be defined with the highest accuracy and show the importance of the preliminary investigation of reliability in positioning facial landmarks. PMID:23515681

  9. Pitfalls at the root of facial assessment on photographs: a quantitative study of accuracy in positioning facial landmarks.

    PubMed

    Cummaudo, M; Guerzoni, M; Marasciuolo, L; Gibelli, D; Cigada, A; Obertovà, Z; Ratnayake, M; Poppa, P; Gabriel, P; Ritz-Timme, S; Cattaneo, C

    2013-05-01

    In the last years, facial analysis has gained great interest also for forensic anthropology. The application of facial landmarks may bring about relevant advantages for the analysis of 2D images by measuring distances and extracting quantitative indices. However, this is a complex task which depends upon the variability in positioning facial landmarks. In addition, literature provides only general indications concerning the reliability in positioning facial landmarks on photographic material, and no study is available concerning the specific errors which may be encountered in such an operation. The aim of this study is to analyze the inter- and intra-observer error in defining facial landmarks on photographs by using a software specifically developed for this purpose. Twenty-four operators were requested to define 22 facial landmarks on frontal view photographs and 11 on lateral view images; in addition, three operators repeated the procedure on the same photographs 20 times (at distance of 24 h). In the frontal view, the landmarks with less dispersion were the pupil, cheilion, endocanthion, and stomion (sto), and the landmarks with the highest dispersion were gonion, zygion, frontotemporale, tragion, and selion (se). In the lateral view, the landmarks with the least dispersion were se, pronasale, subnasale, and sto, whereas landmarks with the highest dispersion were gnathion, pogonion, and tragion. Results confirm that few anatomical points can be defined with the highest accuracy and show the importance of the preliminary investigation of reliability in positioning facial landmarks.

  10. Accuracy of an automatic patient-positioning system based on the correlation of two edge images in radiotherapy.

    PubMed

    Yoon, Myonggeun; Cheong, Minho; Kim, Jinsung; Shin, Dong Ho; Park, Sung Yong; Lee, Se Byeong

    2011-04-01

    We have clinically evaluated the accuracy of an automatic patient-positioning system based on the image correlation of two edge images in radiotherapy. Ninety-six head & neck images from eight patients undergoing proton therapy were compared with a digitally reconstructed radiograph (DRR) of planning CT. Two edge images, a reference image and a test image, were extracted by applying a Canny edge detector algorithm to a DRR and a 2D X-ray image, respectively, of each patient before positioning. In a simulation using a humanoid phantom, performed to verify the effectiveness of the proposed method, no registration errors were observed for given ranges of rotation, pitch, and translation in the x, y, and z directions. For real patients, however, there were discrepancies between the automatic positioning method and manual positioning by physicians or technicians. Using edged head coronal- and sagittal-view images, the average differences in registration between these two methods for the x, y, and z directions were 0.11 cm, 0.09 cm and 0.11 cm, respectively, whereas the maximum discrepancies were 0.34 cm, 0.38 cm, and 0.50 cm, respectively. For rotation and pitch, the average registration errors were 0.95° and 1.00°, respectively, and the maximum errors were 3.6° and 2.3°, respectively. The proposed automatic patient-positioning system based on edge image comparison was relatively accurate for head and neck patients. However, image deformation during treatment may render the automatic method less accurate, since the test image many differ significantly from the reference image.

  11. Positioning System Accuracy Assessment for the Runway Incursion Prevention System Flight Test at the Dallas/Ft. Worth International Airport

    NASA Technical Reports Server (NTRS)

    Quach, Cuong C.

    2004-01-01

    NASA/Langley Research Center collaborated with the Federal Aviation Administration (FAA) to test a Runway Incursion Prevention System (RIPS) at the Dallas Fort Worth International Airport (DFW) in October 2000. The RIPS combines airborne and ground sensor data with various cockpit displays to improve pilots' awareness of traffic conditions on the airport surface. The systems tested at DFW involved surface radar and data systems that gather and send surface traffic information to a research aircraft outfitted with the RIPS software, cockpit displays, and data link transceivers. The data sent to the airborne systems contained identification and GPS location of traffic. This information was compared with the own-ship location from airborne GPS receivers to generate incursion alerts. A total of 93 test tracks were flown while operating RIPS. This report compares the accuracy of the airborne GPS systems that gave the own-ship position of the research aircraft for the 93 test tracks.

  12. Absolute Antenna Calibration at the US National Geodetic Survey

    NASA Astrophysics Data System (ADS)

    Mader, G. L.; Bilich, A. L.

    2012-12-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. Determination of antenna phase center behavior is known as "antenna calibration". Since 1994, NGS has computed relative antenna calibrations for more than 350 antennas. In recent years, the geodetic community has moved to absolute calibrations - the IGS adopted absolute antenna phase center calibrations in 2006 for use in their orbit and clock products, and NGS's CORS group began using absolute antenna calibration upon the release of the new CORS coordinates in IGS08 epoch 2005.00 and NAD 83(2011,MA11,PA11) epoch 2010.00. Although NGS relative calibrations can be and have been converted to absolute, it is considered best practice to independently measure phase center characteristics in an absolute sense. Consequently, NGS has developed and operates an absolute calibration system. These absolute antenna calibrations accommodate the demand for greater accuracy and for 2-dimensional (elevation and azimuth) parameterization. NGS will continue to provide calibration values via the NGS web site www.ngs.noaa.gov/ANTCAL, and will publish calibrations in the ANTEX format as well as the legacy ANTINFO

  13. Mathematical Model for Absolute Magnetic Measuring Systems in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Fügenschuh, Armin; Fügenschuh, Marzena; Ludszuweit, Marina; Mojsic, Aleksandar; Sokół, Joanna

    2015-09-01

    Scales for measuring systems are either based on incremental or absolute measuring methods. Incremental scales need to initialize a measurement cycle at a reference point. From there, the position is computed by counting increments of a periodic graduation. Absolute methods do not need reference points, since the position can be read directly from the scale. The positions on the complete scales are encoded using two incremental tracks with different graduation. We present a new method for absolute measuring using only one track for position encoding up to micrometre range. Instead of the common perpendicular magnetic areas, we use a pattern of trapezoidal magnetic areas, to store more complex information. For positioning, we use the magnetic field where every position is characterized by a set of values measured by a hall sensor array. We implement a method for reconstruction of absolute positions from the set of unique measured values. We compare two patterns with respect to uniqueness, accuracy, stability and robustness of positioning. We discuss how stability and robustness are influenced by different errors during the measurement in real applications and how those errors can be compensated.

  14. Computer-assisted orthognathic surgery: waferless maxillary positioning, versatility, and accuracy of an image-guided visualisation display.

    PubMed

    Zinser, Max J; Mischkowski, Robert A; Dreiseidler, Timo; Thamm, Oliver C; Rothamel, Daniel; Zöller, Joachim E

    2013-12-01

    There may well be a shift towards 3-dimensional orthognathic surgery when virtual surgical planning can be applied clinically. We present a computer-assisted protocol that uses surgical navigation supplemented by an interactive image-guided visualisation display (IGVD) to transfer virtual maxillary planning precisely. The aim of this study was to analyse its accuracy and versatility in vivo. The protocol consists of maxillofacial imaging, diagnosis, planning of virtual treatment, and intraoperative surgical transfer using an IGV display. The advantage of the interactive IGV display is that the virtually planned maxilla and its real position can be completely superimposed during operation through a video graphics array (VGA) camera, thereby augmenting the surgeon's 3-dimensional perception. Sixteen adult class III patients were treated with by bimaxillary osteotomy. Seven hard tissue variables were chosen to compare (ΔT1-T0) the virtual maxillary planning (T0) with the postoperative result (T1) using 3-dimensional cephalometry. Clinically acceptable precision for the surgical planning transfer of the maxilla (<0.35 mm) was seen in the anteroposterior and mediolateral angles, and in relation to the skull base (<0.35°), and marginal precision was seen in the orthogonal dimension (<0.64 mm). An interactive IGV display complemented surgical navigation, augmented virtual and real-time reality, and provided a precise technique of waferless stereotactic maxillary positioning, which may offer an alternative approach to the use of arbitrary splints and 2-dimensional orthognathic planning.

  15. Single-frequency receivers as master permanent stations in GNSS networks: precision and accuracy of the positioning in mixed networks

    NASA Astrophysics Data System (ADS)

    Dabove, Paolo; Manzino, Ambrogio Maria

    2015-04-01

    The use of GPS/GNSS instruments is a common practice in the world at both a commercial and academic research level. Since last ten years, Continuous Operating Reference Stations (CORSs) networks were born in order to achieve the possibility to extend a precise positioning more than 15 km far from the master station. In this context, the Geomatics Research Group of DIATI at the Politecnico di Torino has carried out several experiments in order to evaluate the achievable precision obtainable with different GNSS receivers (geodetic and mass-market) and antennas if a CORSs network is considered. This work starts from the research above described, in particular focusing the attention on the usefulness of single frequency permanent stations in order to thicken the existing CORSs, especially for monitoring purposes. Two different types of CORSs network are available today in Italy: the first one is the so called "regional network" and the second one is the "national network", where the mean inter-station distances are about 25/30 and 50/70 km respectively. These distances are useful for many applications (e.g. mobile mapping) if geodetic instruments are considered but become less useful if mass-market instruments are used or if the inter-station distance between master and rover increases. In this context, some innovative GNSS networks were developed and tested, analyzing the performance of rover's positioning in terms of quality, accuracy and reliability both in real-time and post-processing approach. The use of single frequency GNSS receivers leads to have some limits, especially due to a limited baseline length, the possibility to obtain a correct fixing of the phase ambiguity for the network and to fix the phase ambiguity correctly also for the rover. These factors play a crucial role in order to reach a positioning with a good level of accuracy (as centimetric o better) in a short time and with an high reliability. The goal of this work is to investigate about the

  16. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  17. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  18. Eyes on crowding: crowding is preserved when responding by eye and similarly affects identity and position accuracy.

    PubMed

    Yildirim, Funda; Meyer, Vincent; Cornelissen, Frans W

    2015-02-16

    Peripheral vision guides recognition and selection of targets for eye movements. Crowding—a decline in recognition performance that occurs when a potential target is surrounded by other, similar, objects—influences peripheral object recognition. A recent model study suggests that crowding may be due to increased uncertainty about both the identity and the location of peripheral target objects, but very few studies have assessed these properties in tandem. Eye tracking can integrally provide information on both the perceived identity and the position of a target and therefore could become an important approach in crowding studies. However, recent reports suggest that around the moment of saccade preparation crowding may be significantly modified. If these effects were to generalize to regular crowding tasks, it would complicate the interpretation of results obtained with eye tracking and the comparison to results obtained using manual responses. For this reason, we first assessed whether the manner by which participants responded—manually or by eye—affected their performance. We found that neither recognition performance nor response time was affected by the response type. Hence, we conclude that crowding magnitude was preserved when observers responded by eye. In our main experiment, observers made eye movements to the location of a tilted Gabor target while we varied flanker tilt to manipulate target-flanker similarity. The results indicate that this similarly affected the accuracy of peripheral recognition and saccadic target localization. Our results inform about the importance of both location and identity uncertainty in crowding.

  19. MAGSAT: Vector magnetometer absolute sensor alignment determination

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.

    1981-01-01

    A procedure is described for accurately determining the absolute alignment of the magnetic axes of a triaxial magnetometer sensor with respect to an external, fixed, reference coordinate system. The method does not require that the magnetic field vector orientation, as generated by a triaxial calibration coil system, be known to better than a few degrees from its true position, and minimizes the number of positions through which a sensor assembly must be rotated to obtain a solution. Computer simulations show that accuracies of better than 0.4 seconds of arc can be achieved under typical test conditions associated with existing magnetic test facilities. The basic approach is similar in nature to that presented by McPherron and Snare (1978) except that only three sensor positions are required and the system of equations to be solved is considerably simplified. Applications of the method to the case of the MAGSAT Vector Magnetometer are presented and the problems encountered discussed.

  20. Assessment of the accuracy of PPP for very-high-frequency dynamic, satellite positioning and earthquake modeling

    NASA Astrophysics Data System (ADS)

    Moschas, F.; Avallone, A.; Moschonas, N.; Saltogianni, V.; Stiros, S.

    2012-04-01

    With the advent of various GPS/GNSS Point Positioning techniques, it became possible to model the dynamic displacement history of specific points during large and rather moderate earthquakes using satellite positioning, 1Hz and occasionally 10Hz sampling data. While there is evidence that the obtained data are precise, experience from monitoring of engineering structures like bridges, indicates that GPS/GNSS records are contaminated by coloured (mostly background noise) noise even in the cases of differential-type analysis of the satellite signals. This made the necessary the assessment of the results of different PPP processing using supervised learning techniques. Our work was based on a modification of an experiment first made to assess the potential of GPS to measure oscillations of civil engineering structures. A 10Hz GNSS antenna-receiver unit was mounted on the top of a vertical rod, fixed on the ground and forced to controlled oscillations. Oscillations were also recorded by a robotic theodolite and an accelerometer, and the whole experiment was video-recorded. A second 10Hz GNSS antenna-receiver unit was left on stable ground, in a nearby position. The rod was forced to semi-static motion (bending) and then was left to oscillate freely until still, and the whole movement was recorded by all sensors. GNSS data were analyzed both in kinematic mode and in PPP mode, using the GIPSY-OASIS II (http://gipsy-oasis.jpl.nasa.gov) (only GPS) and the PPP CRCS facility (GPS + GLONAS). Recorded PPP and differential kinematic processing coordinates (apparent displacements) were found to follow the real motion, but to be contaminated by a long-period noise. On the contrary, the short-period component of the apparent PPP displacements, obtained using high-pass filtering, were very much consistent with the real motion, with sub-mm mean deviation, though occasionally contaminated by clipping. The assessment of the very-high frequency GPS noise will provide useful information

  1. Design and implementation of a two-axis micromanipulator to enhance the gripper positional accuracy of a single flexible link

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoying

    1994-05-01

    Accurate and versatile robots are required to perform advanced assembly and manufacturing tasks. To improve the end effector positional accuracy of lightweight robot arms, a two-axis micro-manipulator is mounted between the robot wrist and its manipulator. The rationale is to reduce the wrist sensitivity to the structural deflections of the robotic manipulator. In an attempt to separate the problem of the end-of-arm deflections from the overall control problem of multi-link systems, the micromanipulator is tested on a single flexible link. A laser head with a dual axis photodetector is used to provide direct measurements of the transverse deflections at the free-end of the beam and to detect mechanical inaccuracies caused by manufacturing imperfections and assembly misalignment. The advantages of the integrated system of the micro-manipulator with a single compliant beam are demonstrated and compared to the one without the micro-manipulator for two different control schemes, 'rigid body controller (RBC)' and 'rigid and flexible motion controller (RFMC)' . Both theoretical and experimental results have proven the capability of the micro-manipulator in significantly improving the gripper positional accuracy. Furthermore, it was demonstrated that the micromanipulator tends to complement rather than overlap the effort exerted by the host beam controller. The experimental results have revealed the significant adverse effects of the backlash in gearing on the overall performance of the macro- and micro-manipulators. To address this problem, the dynamic model of the macro- and micro-manipulators is modified to include the dynamics of joint actuators along with the effects of backlash in the indirect drive mechanism of the compliant beam. A general method is developed to handle the dynamic characteristics of backlash in gearing. It entails the derivation of a variable structure model with one auxiliary degree-of-freedom. The latter serves to increase the number of degrees

  2. Positional Accuracy Assessment of the Openstreetmap Buildings Layer Through Automatic Homologous Pairs Detection: the Method and a Case Study

    NASA Astrophysics Data System (ADS)

    Brovelli, M. A.; Minghini, M.; Molinari, M. E.; Zamboni, G.

    2016-06-01

    OpenStreetMap (OSM) is currently the largest openly licensed collection of geospatial data. Being OSM increasingly exploited in a variety of applications, research has placed great attention on the assessment of its quality. This work focuses on assessing the quality of OSM buildings. While most of the studies available in literature are limited to the evaluation of OSM building completeness, this work proposes an original approach to assess the positional accuracy of OSM buildings based on comparison with a reference dataset. The comparison relies on a quasi-automated detection of homologous pairs on the two datasets. Based on the homologous pairs found, warping algorithms like e.g. affine transformations and multi-resolution splines can be applied to the OSM buildings to generate a new version having an optimal local match to the reference layer. A quality assessment of the OSM buildings of Milan Municipality (Northern Italy), having an area of about 180 km2, is then presented. After computing some measures of completeness, the algorithm based on homologous points is run using the building layer of the official vector cartography of Milan Municipality as the reference dataset. Approximately 100000 homologous points are found, which show a systematic translation of about 0.4 m on both the X and Y directions and a mean distance of about 0.8 m between the datasets. Besides its efficiency and high degree of automation, the algorithm generates a warped version of OSM buildings which, having by definition a closest match to the reference buildings, can be eventually integrated in the OSM database.

  3. Criterion validity and accuracy of global positioning satellite and data logging devices for wheelchair tennis court movement

    PubMed Central

    Sindall, Paul; Lenton, John P.; Whytock, Katie; Tolfrey, Keith; Oyster, Michelle L.; Cooper, Rory A.; Goosey-Tolfrey, Victoria L.

    2013-01-01

    Purpose To compare the criterion validity and accuracy of a 1 Hz non-differential global positioning system (GPS) and data logger device (DL) for the measurement of wheelchair tennis court movement variables. Methods Initial validation of the DL device was performed. GPS and DL were fitted to the wheelchair and used to record distance (m) and speed (m/second) during (a) tennis field (b) linear track, and (c) match-play test scenarios. Fifteen participants were monitored at the Wheelchair British Tennis Open. Results Data logging validation showed underestimations for distance in right (DLR) and left (DLL) logging devices at speeds >2.5 m/second. In tennis-field tests, GPS underestimated distance in five drills. DLL was lower than both (a) criterion and (b) DLR in drills moving forward. Reversing drill direction showed that DLR was lower than (a) criterion and (b) DLL. GPS values for distance and average speed for match play were significantly lower than equivalent values obtained by DL (distance: 2816 (844) vs. 3952 (1109) m, P = 0.0001; average speed: 0.7 (0.2) vs. 1.0 (0.2) m/second, P = 0.0001). Higher peak speeds were observed in DL (3.4 (0.4) vs. 3.1 (0.5) m/second, P = 0.004) during tennis match play. Conclusions Sampling frequencies of 1 Hz are too low to accurately measure distance and speed during wheelchair tennis. GPS units with a higher sampling rate should be advocated in further studies. Modifications to existing DL devices may be required to increase measurement precision. Further research into the validity of movement devices during match play will further inform the demands and movement patterns associated with wheelchair tennis. PMID:23820154

  4. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  5. The Carina Project: Absolute and Relative Calibrations

    NASA Astrophysics Data System (ADS)

    Corsi, C. E.; Bono, G.; Walker, A. R.; Brocato, E.; Buonanno, R.; Caputo, F.; Castellani, M.; Castellani, V.; Dall'Ora, M.; Marconi, M.; Monelli, M.; Nonino, M.; Pulone, L.; Ripepi, V.; Smith, H. A.

    We discuss the reduction strategy adopted to perform the relative and the absolute calibration of the Wide Field Imager (WFI) available at the 2.2m ESO/MPI telescope and of the Mosaic Camera (MC) available at the 4m CTIO Blanco telescope. To properly constrain the occurrence of deceptive systematic errors in the relative calibration we observed with each chip the same set of stars. Current photometry seems to suggest that the WFI shows a positional effect when moving from the top to the bottom of individual chips. Preliminary results based on an independent data set collected with the MC suggest that this camera is only marginally affected by the same problem. To perform the absolute calibration we observed with each chip the same set of standard stars. The sample covers a wide color range and the accuracy both in the B and in the V-band appears to be of the order of a few hundredths of magnitude. Finally, we briefly outline the observing strategy to improve both relative and absolute calibrations of mosaic CCD cameras.

  6. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  7. Estimation of the accuracy with which the position of the center of mass of an Interkosmos series artificial earth satellite is calculated. [the effect of atmospheric density

    NASA Technical Reports Server (NTRS)

    Elyasberg, P. Y.; Kugayenko, B. V.; Voyskovskiy, M. I.

    1975-01-01

    The effects of disturbing forces on position calculation, and errors in the initial conditions of motion and in the selected assignment calculation schemes are estimated. It is shown that the main disturbing effects on the accuracy are due to density variations of the upper atmosphere. Recommendations are presented for estimating the calculation accuracy along with an example of such an estimate for the Interkosmos-7 artificial earth satellite. Other factors considered include the adopted scheme and computational algorithms used, effects of disturbing forces not taken into account earlier, and errors in the values of constants and in models of disturbing forces.

  8. Accuracy and efficiency of an infrared based positioning and tracking system for patient set-up and monitoring in image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Jia, Jing; Xu, Gongming; Pei, Xi; Cao, Ruifen; Hu, Liqin; Wu, Yican

    2015-03-01

    An infrared based positioning and tracking (IPT) system was introduced and its accuracy and efficiency for patient setup and monitoring were tested for daily radiotherapy treatment. The IPT system consists of a pair of floor mounted infrared stereoscopic cameras, passive infrared markers and tools used for acquiring localization information as well as a custom controlled software which can perform the positioning and tracking functions. The evaluation of IPT system characteristics was conducted based on the AAPM 147 task report. Experiments on spatial drift and reproducibility as well as static and dynamic localization accuracy were carried out to test the efficiency of the IPT system. Measurements of known translational (up to 55.0 mm) set-up errors in three dimensions have been performed on a calibration phantom. The accuracy of positioning was evaluated on an anthropomorphic phantom with five markers attached to the surface; the precision of the tracking ability was investigated through a sinusoidal motion platform. For the monitoring of the respiration, three volunteers contributed to the breathing testing in real time. The spatial drift of the IPT system was 0.65 mm within 60 min to be stable. The reproducibility of position variations were between 0.01 and 0.04 mm. The standard deviation of static marker localization was 0.26 mm. The repositioning accuracy was 0.19 mm, 0.29 mm, and 0.53 mm in the left/right (L/R), superior/inferior (S/I) and anterior/posterior (A/P) directions, respectively. The measured dynamic accuracy was 0.57 mm and discrepancies measured for the respiratory motion tracking was better than 1 mm. The overall positioning accuracy of the IPT system was within 2 mm. In conclusion, the IPT system is an accurate and effective tool for assisting patient positioning in the treatment room. The characteristics of the IPT system can successfully meet the needs for real time external marker tracking and patient positioning as well as respiration

  9. SHAPES - Spatial, High-Accuracy, Position-Encoding Sensor for multi-point, 3-D position measurement of large flexible structures

    NASA Technical Reports Server (NTRS)

    Nerheim, N. M

    1987-01-01

    An electro-optical position sensor for precise simultaneous measurement of the 3-D positions of multiple points on large space structures is described. The sensor data rate is sufficient for most control purposes. Range is determined by time-of-flight correlation of short laser pulses returned from retroreflector targets using a streak tube/CCD detector. Angular position is determined from target image locations on a second CCD. Experimental verification of dynamic ranging to multiple targets is discussed.

  10. Self-Evaluation Accuracy and Satisfaction with Performance: Are there Affective Costs or Benefits of Positive Self-Evaluation Bias?

    ERIC Educational Resources Information Center

    Narciss, Susanne; Koerndle, Hermann; Dresel, Markus

    2011-01-01

    This paper examines how self-evaluation biases may influence satisfaction with performance. A review of theoretical positions suggests there are two views, both of which are supported by studies involving laboratory tasks. The first view predicts affective costs, and the second affective benefits of positive self-evaluation bias. We test the…

  11. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  12. Accuracy of surface registration compared to conventional volumetric registration in patient positioning for head-and-neck radiotherapy: A simulation study using patient data

    SciTech Connect

    Kim, Youngjun; Li, Ruijiang; Na, Yong Hum; Xing, Lei; Lee, Rena

    2014-12-15

    Purpose: 3D optical surface imaging has been applied to patient positioning in radiation therapy (RT). The optical patient positioning system is advantageous over conventional method using cone-beam computed tomography (CBCT) in that it is radiation free, frameless, and is capable of real-time monitoring. While the conventional radiographic method uses volumetric registration, the optical system uses surface matching for patient alignment. The relative accuracy of these two methods has not yet been sufficiently investigated. This study aims to investigate the theoretical accuracy of the surface registration based on a simulation study using patient data. Methods: This study compares the relative accuracy of surface and volumetric registration in head-and-neck RT. The authors examined 26 patient data sets, each consisting of planning CT data acquired before treatment and patient setup CBCT data acquired at the time of treatment. As input data of surface registration, patient’s skin surfaces were created by contouring patient skin from planning CT and treatment CBCT. Surface registration was performed using the iterative closest points algorithm by point–plane closest, which minimizes the normal distance between source points and target surfaces. Six degrees of freedom (three translations and three rotations) were used in both surface and volumetric registrations and the results were compared. The accuracy of each method was estimated by digital phantom tests. Results: Based on the results of 26 patients, the authors found that the average and maximum root-mean-square translation deviation between the surface and volumetric registrations were 2.7 and 5.2 mm, respectively. The residual error of the surface registration was calculated to have an average of 0.9 mm and a maximum of 1.7 mm. Conclusions: Surface registration may lead to results different from those of the conventional volumetric registration. Only limited accuracy can be achieved for patient

  13. The Influence of Application a Simplified Transformation Model Between Reference Frames ECEF and ECI onto Prediction Accuracy of Position and Velocity of GLONASS Satellites

    NASA Astrophysics Data System (ADS)

    Krzyżek, Robert; Skorupa, Bogdan

    2015-12-01

    In computational tasks of satellite geodesy there is a need for transformation of coordinates between reference frames ECEF - Earth Centered, Earth Fixed and ECI - Earth Centered, Inertial. Strict and simplified transformation models, which can be used in case of the position and velocity short-term predictions of GLONASS satellites, have been presented in this study. Comparison of the results of state vector components predictions of the GLONASS satellites, in dependence of the used transformation model, have also been presented. Accuracy of the prediction has been determined on the basis of the analyse of deviations of the predicted positions and velocities of GLONASS satellites from their values given in broadcast ephemeris.

  14. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  15. Accuracy analysis on C/A code and P(Y) code pseudo-range of GPS dual frequency receiver and application in point positioning

    NASA Astrophysics Data System (ADS)

    Peng, Xiuying; Fan, Shijie; Guo, Jiming

    2008-10-01

    When the Anti-Spoofing (A-S) is active, the civilian users have some difficulties in using the P(Y) code for precise navigation and positioning. Z-tracking technique is one of the effective methods to acquire the P(Y) code. In this paper, the accuracy of pseudoranges from C/A code and P(Y) code for dual frequency GPS receiver is discussed. The principle of measuring the encrypted P(Y) code is described firstly, then a large data set from IGS tracking stations is utilized for analysis and verification with the help of a precise point positioning software developed by authors. Especially, P(Y) code pseudoranges of civilian GPS receivers allow eliminating/reducing the effect of ionospheric delay and improve the precision of positioning. The point positioning experiments for this are made in the end.

  16. Robotic-based carbon ion therapy and patient positioning in 6 degrees of freedom: setup accuracy of two standard immobilization devices used in carbon ion therapy and IMRT

    PubMed Central

    2012-01-01

    Purpose To investigate repositioning accuracy in particle radiotherapy in 6 degrees of freedom (DOF) and intensity-modulated radiotherapy (IMRT, 3 DOF) for two immobilization devices (Scotchcast masks vs thermoplastic head masks) currently in use at our institution for fractionated radiation therapy in head and neck cancer patients. Methods and materials Position verifications in patients treated with carbon ion therapy and IMRT for head and neck malignancies were evaluated. Most patients received combined treatment regimen (IMRT plus carbon ion boost), immobilization was achieved with either Scotchcast or thermoplastic head masks. Position corrections in robotic-based carbon ion therapy allowing 6 DOF were compared to IMRT allowing corrections in 3 DOF for two standard immobilization devices. In total, 838 set-up controls of 38 patients were analyzed. Results Robotic-based position correction including correction of rotations was well tolerated and without discomfort. Standard deviations of translational components were between 0.5 and 0.8 mm for Scotchcast and 0.7 and 1.3 mm for thermoplastic masks in 6 DOF and 1.2 - 1.4 mm and 1.0 - 1.1 mm in 3 DOF respectively. Mean overall displacement vectors were between 2.1 mm (Scotchcast) and 2.9 mm (thermoplastic masks) in 6 DOF and 3.9 - 3.0 mm in 3 DOF respectively. Displacement vectors were lower when correction in 6 DOF was allowed as opposed to 3 DOF only, which was maintained at the traditional action level of > 3 mm for position correction in the pre-on-board imaging era. Conclusion Setup accuracy for both systems was within the expected range. Smaller shifts were required when 6 DOF were available for correction as opposed to 3 DOF. Where highest possible positioning accuracy is required, frequent image guidance is mandatory to achieve best possible plan delivery and maintenance of sharp gradients and optimal normal tissue sparing inherent in carbon ion therapy. PMID:22458824

  17. Low-dose CT imaging of radio-opaque markers for assessing human rotator cuff repair: accuracy, repeatability and the effect of arm position.

    PubMed

    Derwin, K A; Milks, R A; Davidson, I; Iannotti, J P; McCarron, J A; Bey, M J

    2012-02-01

    Previous studies have used radiostereometric analysis (RSA) to assess the integrity and mechanical properties of repaired tendons and ligament grafts. A conceptually similar approach is to use CT imaging to measure the 3D position and distance between implanted markers. The purpose of this study was to quantify the accuracy and repeatability of measuring the position and distance between metallic markers placed in the rotator cuff using low-dose CT imaging. We also investigated the effect of repeated or variable positions of the arm on position and distance measures. Six human patients had undergone rotator cuff repair and placement of tantalum beads in the rotator cuff at least one year prior to participating in this study. On a single day each patient underwent nine low-dose CT scans in seven unique arm positions. CT scans were analyzed to assess bias, precision and RMS error of the measurement technique. The effect of repeated or variable positions of the arm on the 3D position of the beads and the distance between these beads and suture anchors in the humeral head were also assessed. Results showed the CT imaging method is accurate and repeatable to within 0.7 mm. Further, measures of bead position and anchor-to-bead distance are influenced by arm position and location of the bead within the rotator cuff. Beads located in the posterior rotator cuff moved medially as much as 20 mm in abduction or external rotation. When clinically relevant CT arm positions such as the hand on umbilicus or at side were repeated, bead position varied less than 4 mm in any anatomic direction and anchor-to-bead distance varied +2.8 to -1.6 mm (RMS 1.3 mm). We conclude that a range of ± 3 mm is a conservative estimate of the uncertainty in anchor-to-bead distance for patients repeatedly scanned in clinically-relevant arm positions.

  18. Further improvements in deconvolution of pass-through paleomagnetic measurement data: Accuracy of positioning and sensor response

    NASA Astrophysics Data System (ADS)

    Oda, H.; Xuan, C.; Yamamoto, Y.

    2015-12-01

    Pass-through superconducting rock magnetometer (SRM) is one of the most important tools for modern paleomagnetism research. It offers rapid and continuous measurements of weak remanent magnetization preserved in various geological archives. However, pass-through SRM measurements are inevitably smoothed and even distorted due to the convolution effect of the SRM sensor response, and deconvolution is necessary to restore high-resolution signal from pass-through measurements. Reliable deconvolution relies on accurate estimate of the SRM sensor response and our understanding of errors associated with sample measurements. In this presentation, we introduce new practical tool and procedure to facilitate rapid and accurate measurements of SRM sensor response with demonstration using an SRM at the Kochi Core Center, Japan. We also report accurate measurements of SRM tray positions measured using laser interferometry. The measured positions with an actual u-channel sample on the tray show vibrations with peak amplitudes of ~50μm following each stop of the tray. The vibrations diminish towards background level in ~0.4 sec. Comparison with the positions expected from the stepping motor counts show random discrepancies with standard deviations of 0.1~0.2 mm. Measurements with u-channel show higher standard deviations including significant stepwise changes of up to ~0.5mm.

  19. GNSS Absolute Antenna Calibration at the National Geodetic Survey

    NASA Astrophysics Data System (ADS)

    Mader, G. L.; Bilich, A. L.; Geoghegan, C.

    2011-12-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. To help meet the needs of the high-precision GNSS community, the National Geodetic Survey (NGS) now operates an absolute antenna calibration facility. Located in Corbin, Virginia, this facility uses field measurements and actual GNSS satellite signals to quantitatively determine the carrier phase advance/delay introduced by the antenna element. The NGS facility was built to serve traditional NGS constituents such as the surveying and geodesy communities, however calibration services are open and available to all GNSS users as the calibration schedule permits. All phase center patterns computed by this facility will be publicly available and disseminated in both the ANTEX and NGS formats. We describe the NGS calibration facility, and discuss the observation models and strategy currently used to generate NGS absolute calibrations. We demonstrate that NGS absolute phase center variation (PCV) patterns are consistent with published values determined by other absolute antenna calibration facilities, and compare absolute calibrations to the traditional NGS relative calibrations.

  20. Friends' knowledge of youth internalizing and externalizing adjustment: accuracy, bias, and the influences of gender, grade, positive friendship quality, and self-disclosure.

    PubMed

    Swenson, Lance P; Rose, Amanda J

    2009-08-01

    Some evidence suggests that close friends may be knowledgeable of youth's psychological adjustment. However, friends are understudied as reporters of adjustment. The current study examines associations between self- and friend-reports of internalizing and externalizing adjustment in a community sample of fifth-, eighth-, and eleventh-grade youth. The study extends prior work by considering the degree to which friends' reports of youth adjustment are accurate (i.e., predicted by youths' actual adjustment) versus biased (i.e., predicted by the friend reporters' own adjustment). Findings indicated stronger bias effects than accuracy effects, but the accuracy effects were significant for both internalizing and externalizing adjustment. Additionally, friends who perceived their relationships as high in positive quality, friends in relationships high in disclosure, and girls perceived youths' internalizing symptoms most accurately. Knowledge of externalizing adjustment was not influenced by gender, grade, relationship quality, or self-disclosure. Findings suggest that friends could play an important role in prevention efforts.

  1. Study of accuracy in the position determination with SALSA, a γ-scanning system for the characterization of segmented HPGe detectors

    NASA Astrophysics Data System (ADS)

    Hernandez-Prieto, A.; Quintana, B.; Martìn, S.; Domingo-Pardo, C.

    2016-07-01

    Accurate characterization of the electric response of segmented high-purity germanium (HPGe) detectors as a function of the interaction position is one of the current goals of the Nuclear Physics community seeking to perform γ-ray tracking or even imaging with these detectors. For this purpose, scanning devices must be developed to achieve the signal-position association with the highest precision. With a view to studying the accuracy achieved with SALSA, the SAlamanca Lyso-based Scanning Array, here we report a detailed study on the uncertainty sources and their effect in the position determination inside the HPGe detector to be scanned. The optimization performed on the design of SALSA, aimed at minimizing the effect of the uncertainty sources, afforded an intrinsic uncertainty of ∼2 mm for large coaxial detectors and ∼1 mm for planar ones.

  2. Development of X-Y Servo Pneumatic-Piezoelectric Hybrid Actuators for Position Control with High Response, Large Stroke and Nanometer Accuracy

    PubMed Central

    Chiang, Mao-Hsiung

    2010-01-01

    This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally. PMID:22319266

  3. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  4. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  5. Improved accuracy and speed in scanning probe microscopy by image reconstruction from non-gridded position sensor data.

    PubMed

    Ziegler, Dominik; Meyer, Travis R; Farnham, Rodrigo; Brune, Christoph; Bertozzi, Andrea L; Ashby, Paul D

    2013-08-23

    Scanning probe microscopy (SPM) has facilitated many scientific discoveries utilizing its strengths of spatial resolution, non-destructive characterization and realistic in situ environments. However, accurate spatial data are required for quantitative applications but this is challenging for SPM especially when imaging at higher frame rates. We present a new operation mode for scanning probe microscopy that uses advanced image processing techniques to render accurate images based on position sensor data. This technique, which we call sensor inpainting, frees the scanner to no longer be at a specific location at a given time. This drastically reduces the engineering effort of position control and enables the use of scan waveforms that are better suited for the high inertia nanopositioners of SPM. While in raster scanning, typically only trace or retrace images are used for display, in Archimedean spiral scans 100% of the data can be displayed and at least a two-fold increase in temporal or spatial resolution is achieved. In the new mode, the grid size of the final generated image is an independent variable. Inpainting to a few times more pixels than the samples creates images that more accurately represent the ground truth.

  6. Accuracy of Ultrasound-Based Image Guidance for Daily Positioning of the Upper Abdomen: An Online Comparison With Cone Beam CT

    SciTech Connect

    Boda-Heggemann, Judit Mennemeyer, Philipp; Wertz, Hansjoerg; Riesenacker, Nadja; Kuepper, Beate; Lohr, Frank; Wenz, Frederik

    2009-07-01

    Purpose: Image-guided intensity-modulated radiotherapy can improve protection of organs at risk when large abdominal target volumes are irradiated. We estimated the daily positioning accuracy of ultrasound-based image guidance for abdominal target volumes by a direct comparison of daily imaging obtained with cone beam computed tomography (CBCT). Methods and Materials: Daily positioning (n = 83 positionings) of 15 patients was completed by using ultrasound guidance after an initial CBCT was obtained. Residual error after ultrasound was estimated by comparison with a second CBCT. Ultrasound image quality was visually rated using a scale of 1 to 4. Results: Of 15 patients, 7 patients had good sonographic imaging quality, 5 patients had satisfactory sonographic quality, and 3 patients were excluded because of unsatisfactory sonographic quality. When image quality was good, residual errors after ultrasound were -0.1 {+-} 3.11 mm in the x direction (left-right; group systematic error M = -0.09 mm; standard deviation [SD] of systematic error, {sigma} = 1.37 mm; SD of the random error, {sigma} = 2.99 mm), 0.93 {+-} 4.31 mm in the y direction (superior-inferior, M = 1.12 mm; {sigma} = 2.96 mm; {sigma} = 3.39 mm), and 0.71 {+-} 3.15 mm in the z direction (anteroposterior; M = 1.01 mm; {sigma} = 2.46 mm; {sigma} = 2.24 mm). For patients with satisfactory image quality, residual error after ultrasound was -0.6 {+-} 5.26 mm in the x (M = 0.07 mm; {sigma} = 5.67 mm; {sigma} = 4.86 mm), 1.76 {+-} 4.92 mm in the y (M = 3.54 mm; {sigma} = 4.1 mm; {sigma} = 5.29 mm), and 1.19 {+-} 4.75 mm in the z (M = 0.82 mm; {sigma} = 2.86 mm; {sigma} = 3.05 mm) directions. Conclusions: In patients from whom good sonographic image quality could be obtained, ultrasound improved daily positioning accuracy. In the case of satisfactory image quality, ultrasound guidance improved accuracy compared to that of skin marks only minimally. If sonographic image quality was unsatisfactory, daily CBCT

  7. Accuracy of an infrared marker-based patient positioning system (ExacTrac®) for stereotactic body radiotherapy in localizing the planned isocenter using fiducial markers

    NASA Astrophysics Data System (ADS)

    Montes-Rodríguez, María de los Ángeles; Hernández-Bojórquez, Mariana; Martínez-Gómez, Alma Angélica; Contreras-Pérez, Agustín; Negrete-Hernández, Ingrid Mireya; Hernández-Oviedo, Jorge Omar; Mitsoura, Eleni; Santiago-Concha, Bernardino Gabriel

    2014-11-01

    Stereotactic Body Radiation Therapy (SBRT) requires a controlled immobilization and position monitoring of patient and target. The purpose of this work is to analyze the performance of the imaging system ExacTrac® (ETX) using infrared and fiducial markers. Materials and methods: In order to assure the accuracy of isocenter localization, a Quality Assurance procedure was applied using an infrared marker-based positioning system. Scans were acquired of an inhouse-agar gel and solid water phantom with infrared spheres. In the inner part of the phantom, three reference markers were delineated as reference and one pellet was place internally; which was assigned as the isocenter. The iPlan® RT Dose treatment planning system. Images were exported to the ETX console. Images were acquired with the ETX to check the correctness of the isocenter placement. Adjustments were made in 6D the reference markers were used to fuse the images. Couch shifts were registered. The procedure was repeated for verification purposes. Results: The data recorded of the verifications in translational and rotational movements showed averaged 3D spatial uncertainties of 0.31 ± 0.42 mm respectively 0.82° ± 0.46° in the phantom and the first correction of these uncertainties were of 1.51 ± 1.14 mm respectively and 1.37° ± 0.61°. Conclusions: This study shows a high accuracy and repeatability in positioning the selected isocenter. The ETX-system for verifying the treatment isocenter position has the ability to monitor the tracing position of interest, making it possible to be used for SBRT positioning within uncertainty ≤1mm.

  8. Accuracy of an infrared marker-based patient positioning system (ExacTrac®) for stereotactic body radiotherapy in localizing the planned isocenter using fiducial markers

    SciTech Connect

    Montes-Rodríguez, María de los Ángeles Mitsoura, Eleni; Hernández-Bojórquez, Mariana; Martínez-Gómez, Alma Angélica; Contreras-Pérez, Agustín; Negrete-Hernández, Ingrid Mireya; Hernández-Oviedo, Jorge Omar; Santiago-Concha, Bernardino Gabriel

    2014-11-07

    Stereotactic Body Radiation Therapy (SBRT) requires a controlled immobilization and position monitoring of patient and target. The purpose of this work is to analyze the performance of the imaging system ExacTrac® (ETX) using infrared and fiducial markers. Materials and methods: In order to assure the accuracy of isocenter localization, a Quality Assurance procedure was applied using an infrared marker-based positioning system. Scans were acquired of an inhouse-agar gel and solid water phantom with infrared spheres. In the inner part of the phantom, three reference markers were delineated as reference and one pellet was place internally; which was assigned as the isocenter. The iPlan® RT Dose treatment planning system. Images were exported to the ETX console. Images were acquired with the ETX to check the correctness of the isocenter placement. Adjustments were made in 6D the reference markers were used to fuse the images. Couch shifts were registered. The procedure was repeated for verification purposes. Results: The data recorded of the verifications in translational and rotational movements showed averaged 3D spatial uncertainties of 0.31 ± 0.42 mm respectively 0.82° ± 0.46° in the phantom and the first correction of these uncertainties were of 1.51 ± 1.14 mm respectively and 1.37° ± 0.61°. Conclusions: This study shows a high accuracy and repeatability in positioning the selected isocenter. The ETX-system for verifying the treatment isocenter position has the ability to monitor the tracing position of interest, making it possible to be used for SBRT positioning within uncertainty ≤1mm.

  9. Absolute Income, Relative Income, and Happiness

    ERIC Educational Resources Information Center

    Ball, Richard; Chernova, Kateryna

    2008-01-01

    This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

  10. The AFGL absolute gravity program

    NASA Technical Reports Server (NTRS)

    Hammond, J. A.; Iliff, R. L.

    1978-01-01

    A brief discussion of the AFGL's (Air Force Geophysics Laboratory) program in absolute gravity is presented. Support of outside work and in-house studies relating to gravity instrumentation are discussed. A description of the current transportable system is included and the latest results are presented. These results show good agreement with measurements at the AFGL site by an Italian system. The accuracy obtained by the transportable apparatus is better than 0.1 microns sq sec 10 microgal and agreement with previous measurements is within the combined uncertainties of the measurements.

  11. Disturbance in hitting accuracy by professional and collegiate baseball players due to intentional change of target position.

    PubMed

    Higuchi, Takatoshi; Nagami, Tomoyuki; Morohoshi, Jun; Nakata, Hiroki; Kanosue, Kazuyuki

    2013-04-01

    The present study investigated bat control of skilled baseball batters during tee batting, faced with an intentional change in target position. Twelve, skilled, male baseball players (M age = 24 yr., SD = 4) participated in the study. Participants were instructed to hit a baseball off a tee 0.8 m from the ground (Hitting condition), and also to deliberately swing just above the ball (Air Swing condition). The task for the participants was to perform, in alternate order, 15 swings at a real baseball on a stationary tee and 15 swings at an imaginary ball that was said to be on top of the real baseball. The participants were instructed to hit the ball toward center field just as they would hit in a game. While most participants could hit the real ball in the sweet area of the bat, only one participant did so in the Air Swing condition. Average distances from the center of the sweet area to ball center at the moment of ball-bat contact in the Air Swing condition (85 mm) were significantly greater than the distance in the Hitting condition (38 mm). The larger error in hitting an imaginary ball in the sweet area could be due to perceptual changes following the batter's altered focus, expectation of a lack of contact, and/or lack of feedback from the swing. It was suggested that baseball batters should be aware of the possible error in hitting accurately when they intentionally shifted the target. PMID:24032335

  12. Disturbance in hitting accuracy by professional and collegiate baseball players due to intentional change of target position.

    PubMed

    Higuchi, Takatoshi; Nagami, Tomoyuki; Morohoshi, Jun; Nakata, Hiroki; Kanosue, Kazuyuki

    2013-04-01

    The present study investigated bat control of skilled baseball batters during tee batting, faced with an intentional change in target position. Twelve, skilled, male baseball players (M age = 24 yr., SD = 4) participated in the study. Participants were instructed to hit a baseball off a tee 0.8 m from the ground (Hitting condition), and also to deliberately swing just above the ball (Air Swing condition). The task for the participants was to perform, in alternate order, 15 swings at a real baseball on a stationary tee and 15 swings at an imaginary ball that was said to be on top of the real baseball. The participants were instructed to hit the ball toward center field just as they would hit in a game. While most participants could hit the real ball in the sweet area of the bat, only one participant did so in the Air Swing condition. Average distances from the center of the sweet area to ball center at the moment of ball-bat contact in the Air Swing condition (85 mm) were significantly greater than the distance in the Hitting condition (38 mm). The larger error in hitting an imaginary ball in the sweet area could be due to perceptual changes following the batter's altered focus, expectation of a lack of contact, and/or lack of feedback from the swing. It was suggested that baseball batters should be aware of the possible error in hitting accurately when they intentionally shifted the target.

  13. Precision of high-resolution multibeam echo sounding coupled with high-accuracy positioning in a shallow water coastal environment

    NASA Astrophysics Data System (ADS)

    Ernstsen, Verner B.; Noormets, Riko; Hebbeln, Dierk; Bartholomä, Alex; Flemming, Burg W.

    2006-09-01

    Over 4 years, repetitive bathymetric measurements of a shipwreck in the Grådyb tidal inlet channel in the Danish Wadden Sea were carried out using a state-of-the-art high-resolution multibeam echosounder (MBES) coupled with a real-time long range kinematic (LRK™) global positioning system. Seven measurements during a single survey in 2003 ( n=7) revealed a horizontal and vertical precision of the MBES system of ±20 and ±2 cm, respectively, at a 95% confidence level. By contrast, four annual surveys from 2002 to 2005 ( n=4) yielded a horizontal and vertical precision (at 95% confidence level) of only ±30 and ±8 cm, respectively. This difference in precision can be explained by three main factors: (1) the dismounting of the system between the annual surveys, (2) rougher sea conditions during the survey in 2004 and (3) the limited number of annual surveys. In general, the precision achieved here did not correspond to the full potential of the MBES system, as this could certainly have been improved by an increase in coverage density (soundings/m2), achievable by reducing the survey speed of the vessel. Nevertheless, precision was higher than that reported to date for earlier offshore test surveys using comparable equipment.

  14. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  15. Interplay effects between dose distribution quality and positioning accuracy in total marrow irradiation with volumetric modulated arc therapy

    SciTech Connect

    Mancosu, Pietro; Navarria, Piera; Reggiori, Giacomo; Tomatis, Stefano; Alongi, Filippo; Scorsetti, Marta; Castagna, Luca; Sarina, Barbara; Nicolini, Giorgia; Fogliata, Antonella; Cozzi, Luca

    2013-11-15

    Purpose: To evaluate the dosimetric consequences of inaccurate isocenter positioning during treatment of total marrow (lymph-node) irradiation (TMI-TMLI) using volumetric modulated arc therapy (VMAT).Methods: Four patients treated with TMI and TMLI were randomly selected from the internal database. Plans were optimized with VMAT technique. Planning target volume (PTV) included all the body bones; for TMLI, lymph nodes and spleen were considered into the target, too. Dose prescription to PTV was 12 Gy in six fractions, two times per day for TMI, and 2 Gy in single fraction for TMLI. Ten arcs on five isocenters (two arcs for isocenter) were used to cover the upper part of PTV (i.e., from cranium to middle femurs). For each plan, three series of random shifts with values between −3 and +3 mm and three between −5 and +5 mm were applied to the five isocenters simulating involuntary patient motion during treatment. The shifts were applied separately in the three directions: left–right (L-R), anterior–posterior (A-P), and cranial–caudal (C-C). The worst case scenario with simultaneous random shifts in all directions simultaneously was considered too. Doses were recalculated for the 96 shifted plans (24 for each patient).Results: For all shifts, differences <0.5% were found for mean doses to PTV, body, and organs at risk with volumes >100 cm{sup 3}. Maximum doses increased up to 15% for C-C shifted plans. PTV covered by the 95% isodose decreased of 2%–8% revealing target underdosage with the highest values in C-C direction.Conclusions: The correct isocenter repositioning of TMI-TMLI patients is fundamental, in particular in C-C direction, in order to avoid over- and underdosages especially in the overlap regions. For this reason, a dedicated immobilization system was developed in the authors' center to best immobilize the patient.

  16. Performance and Accuracy of Lightweight and Low-Cost GPS Data Loggers According to Antenna Positions, Fix Intervals, Habitats and Animal Movements.

    PubMed

    Forin-Wiart, Marie-Amélie; Hubert, Pauline; Sirguey, Pascal; Poulle, Marie-Lazarine

    2015-01-01

    Recently developed low-cost Global Positioning System (GPS) data loggers are promising tools for wildlife research because of their affordability for low-budget projects and ability to simultaneously track a greater number of individuals compared with expensive built-in wildlife GPS. However, the reliability of these devices must be carefully examined because they were not developed to track wildlife. This study aimed to assess the performance and accuracy of commercially available GPS data loggers for the first time using the same methods applied to test built-in wildlife GPS. The effects of antenna position, fix interval and habitat on the fix-success rate (FSR) and location error (LE) of CatLog data loggers were investigated in stationary tests, whereas the effects of animal movements on these errors were investigated in motion tests. The units operated well and presented consistent performance and accuracy over time in stationary tests, and the FSR was good for all antenna positions and fix intervals. However, the LE was affected by the GPS antenna and fix interval. Furthermore, completely or partially obstructed habitats reduced the FSR by up to 80% in households and increased the LE. Movement across habitats had no effect on the FSR, whereas forest habitat influenced the LE. Finally, the mean FSR (0.90 ± 0.26) and LE (15.4 ± 10.1 m) values from low-cost GPS data loggers were comparable to those of built-in wildlife GPS collars (71.6% of fixes with LE < 10 m for motion tests), thus confirming their suitability for use in wildlife studies.

  17. Performance and Accuracy of Lightweight and Low-Cost GPS Data Loggers According to Antenna Positions, Fix Intervals, Habitats and Animal Movements

    PubMed Central

    Forin-Wiart, Marie-Amélie; Hubert, Pauline; Sirguey, Pascal; Poulle, Marie-Lazarine

    2015-01-01

    Recently developed low-cost Global Positioning System (GPS) data loggers are promising tools for wildlife research because of their affordability for low-budget projects and ability to simultaneously track a greater number of individuals compared with expensive built-in wildlife GPS. However, the reliability of these devices must be carefully examined because they were not developed to track wildlife. This study aimed to assess the performance and accuracy of commercially available GPS data loggers for the first time using the same methods applied to test built-in wildlife GPS. The effects of antenna position, fix interval and habitat on the fix-success rate (FSR) and location error (LE) of CatLog data loggers were investigated in stationary tests, whereas the effects of animal movements on these errors were investigated in motion tests. The units operated well and presented consistent performance and accuracy over time in stationary tests, and the FSR was good for all antenna positions and fix intervals. However, the LE was affected by the GPS antenna and fix interval. Furthermore, completely or partially obstructed habitats reduced the FSR by up to 80% in households and increased the LE. Movement across habitats had no effect on the FSR, whereas forest habitat influenced the LE. Finally, the mean FSR (0.90 ± 0.26) and LE (15.4 ± 10.1 m) values from low-cost GPS data loggers were comparable to those of built-in wildlife GPS collars (71.6% of fixes with LE < 10 m for motion tests), thus confirming their suitability for use in wildlife studies. PMID:26086958

  18. Absolute GNSS Antenna Calibration at the National Geodetic Survey

    NASA Astrophysics Data System (ADS)

    Mader, G.; Bilich, A.; Geoghegan, C.

    2012-04-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. To help meet the needs of the high-precision GNSS community, the National Geodetic Survey (NGS) now operates an absolute antenna calibration facility. Located in Corbin, Virginia, this facility uses field measurements and actual GNSS satellite signals to quantitatively determine the carrier phase advance/delay introduced by the antenna element. The NGS facility was built to serve traditional NGS constituents such as the surveying and geodesy communities, however calibration services are open and available to all GNSS users as the calibration schedule permits. All phase center patterns computed by this facility will be publicly available and disseminated in both the ANTEX and NGS formats. We describe the NGS calibration facility, and discuss the observation models and strategy currently used to generate NGS absolute calibrations. We demonstrate that NGS absolute phase center variation (PCV) patterns are consistent with published values determined by other absolute antenna calibration facilities, and outline future planned refinements to the system.

  19. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  20. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses.

  1. Effect of changing patient position from supine to prone on the accuracy of a Cosman-Roberts-Wells (CRW) stereotactic head frame system

    NASA Astrophysics Data System (ADS)

    Rohlfing, Torsten; Maurer, Calvin R., Jr.; Dean, David; Maciunas, Robert J.

    2002-05-01

    Despite the growing popularity of frameless image-guided surgery systems, stereotactic head frame systems are widely accepted by neurosurgeons and are still commonly used to perform stereotactic biopsy, functional procedures, and stereotactic radiosurgery. In this study, we investigate the accuracy of the Cosman-Roberts-Wells (CRW) stereotactic frame system when the mechanical load on the frame changes between pre-operative imaging and the intervention due to different patient position - supine during imaging, prone during intervention. We analyze CT images acquired from 12 patients who underwent stereotactic biopsy or stereotactic radiosurgery. Two CT images were acquired for each patient, one with the patient in the supine position and one in the prone position. The prone images were registered to the respective supine images using an intensity-based registration algorithm, once using only the frame and once using only the head. The difference between the transformations produced by these two registrations describes the movement of the patient's head with respect to the frame due to mechanical distortion of the latter. The maximum frame-based registration error between supine and prone positions was 2.8 mm, greater than 2 mm in two patients, and greater than 1.5 mm in five patients. Anterior-posterior translation is the dominant component of the difference transformation for most of these patients. In general, the magnitude of the movement increased with brain volume, which is an index of head weight. We conclude that in order to minimize frame-based registration error due to a change in the mechanical load on the frame, frame-based stereotactic procedures should be performed with the patient in the identical position during imaging and intervention.

  2. On the accuracy of approximation of a small celestial body motion using intermediate perturbed orbits calculated from two position vectors and three observations

    NASA Astrophysics Data System (ADS)

    Shefer, V. A.; Shefer, O. V.

    2015-01-01

    We examine intermediate perturbed orbits proposed by the first author previously, defined from the two position vectors and three angular coordinates of a small celestial body. It is shown theoretically, that at a small reference time interval covering the measurements the approximation accuracy of real movements by these orbits corresponds approximately to the third order of osculation. The smaller reference interval of time, the better this correspondence. Laws of variation of the methodical errors in constructing intermediate orbits subject to the length of reference time interval are deduced. According to these laws, the convergence rate of the methods to the exact solution (upon reducing the reference interval of time) is higher by two orders of magnitude than in the case of conventional methods using the Keplerian unperturbed orbit. The considered orbits are among the most accurate in set of orbits of their class determined by the order of osculation. The theoretical results are validated by numerical examples.

  3. Location Accuracy Improvements in the Japanese Lightning Detection Network by Eliminating the Data Obtained from Distant Sensors from Lightning Stroke Positions

    NASA Astrophysics Data System (ADS)

    Matsui, M.; Michishita, K.

    2015-12-01

    Authors have observed the current waveform of lightning flashes by the Rogowski coils installed at the wind turbines located in southern Kyushu, Japan. We succeeded in observing three sets of lightning current waveforms of negative downward flashes hit to the wind turbine and estimated the location error by comparing the actual position with the positions located by the Japanese Lightning Detection Network (JLDN) in two summer seasons between 2013 and 2014. The JLDN is a Lightning Locating System consisting of 30 LF sensors installed for observing lightning in the whole area of Japan. According to our estimation, the mean location error of the first strokes was 557m and that of subsequent ones was 316 m in the JLDN, respectively. This means the location accuracy of the JLDN was slightly less than that of the NALDN and the EUCLID. We found out location errors were less than 400 m when only information from sensors within 700 km from lightning strokes was used for locating stroke positions. Therefore, we recalculated locations of those lightning strokes without information from sensors at more than 700 km from them. In the results of the recalculation, the mean location error of the first strokes was improved by 219 m and that of subsequent ones was improved by 48 m, respectively. This indicates eliminating large deviation data from distant sensors for lightning location reduced the standard deviation of the time differences between actually measured time at sensors and calculated time and thus improved location error of the JLDN. We found out that there were strong positive relations between the location errors and the standard deviation of the time differences. The standard deviations of the time difference were less than 1.5 micro-seconds when location errors were within 400 m. Therefore, locating lightning strokes without information from distant sensors is a useful method for reducing the standard deviation and improving location error.

  4. High-precision positioning of radar scatterers

    NASA Astrophysics Data System (ADS)

    Dheenathayalan, Prabu; Small, David; Schubert, Adrian; Hanssen, Ramon F.

    2016-05-01

    Remote sensing radar satellites cover wide areas and provide spatially dense measurements, with millions of scatterers. Knowledge of the precise position of each radar scatterer is essential to identify the corresponding object and interpret the estimated deformation. The absolute position accuracy of synthetic aperture radar (SAR) scatterers in a 2D radar coordinate system, after compensating for atmosphere and tidal effects, is in the order of centimeters for TerraSAR-X (TSX) spotlight images. However, the absolute positioning in 3D and its quality description are not well known. Here, we exploit time-series interferometric SAR to enhance the positioning capability in three dimensions. The 3D positioning precision is parameterized by a variance-covariance matrix and visualized as an error ellipsoid centered at the estimated position. The intersection of the error ellipsoid with objects in the field is exploited to link radar scatterers to real-world objects. We demonstrate the estimation of scatterer position and its quality using 20 months of TSX stripmap acquisitions over Delft, the Netherlands. Using trihedral corner reflectors (CR) for validation, the accuracy of absolute positioning in 2D is about 7 cm. In 3D, an absolute accuracy of up to ˜ 66 cm is realized, with a cigar-shaped error ellipsoid having centimeter precision in azimuth and range dimensions, and elongated in cross-range dimension with a precision in the order of meters (the ratio of the ellipsoid axis lengths is 1/3/213, respectively). The CR absolute 3D position, along with the associated error ellipsoid, is found to be accurate and agree with the ground truth position at a 99 % confidence level. For other non-CR coherent scatterers, the error ellipsoid concept is validated using 3D building models. In both cases, the error ellipsoid not only serves as a quality descriptor, but can also help to associate radar scatterers to real-world objects.

  5. Lack of Correlation Between External Fiducial Positions and Internal Tumor Positions During Breath-Hold CT

    SciTech Connect

    Hunjan, Sandeep; Starkschall, George; Prado, Karl; Dong Lei; Balter, Peter

    2010-04-15

    Purpose: For thoracic tumors, if four-dimensional computed tomography (4DCT) is unavailable, the internal margin can be estimated by use of breath-hold (BH) CT scans acquired at end inspiration (EI) and end expiration (EE). By use of external surrogates for tumor position, BH accuracy is estimated by minimizing the difference between respiratory extrema BH and mean equivalent-phase free breathing (FB) positions. We tested the assumption that an external surrogate for BH accuracy correlates with internal tumor positional accuracy during BH CT. Methods and Materials: In 16 lung cancer patients, 4DCT images, as well as BH CT images at EI and EE, were acquired. Absolute differences between BH and mean equivalent-phase (FB) positions were calculated for both external fiducials and gross tumor volume (GTV) centroids as metrics of external and internal BH accuracy, respectively, and the results were correlated. Results: At EI, the absolute difference between mean FB and BH fiducial displacement correlated poorly with the absolute difference between FB and BH GTV centroid positions on CT images (R{sup 2} = 0.11). Similarly, at EE, the absolute difference between mean FB and BH fiducial displacements correlated poorly with the absolute difference between FB and BH GTV centroid positions on CT images (R{sup 2} = 0.18). Conclusions: External surrogates for tumor position are not an accurate metric of BH accuracy for lung cancer patients. This implies that care should be taken when using such an approach because an incorrect internal margin could be generated.

  6. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  7. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  8. Precise determination of the absolute isotopic abundance ratio and the atomic weight of chlorine in three international reference materials by the positive thermal ionization mass spectrometer-Cs2Cl+-graphite method.

    PubMed

    Wei, Hai-Zhen; Jiang, Shao-Yong; Xiao, Ying-Kai; Wang, Jun; Lu, Hai; Wu, Bin; Wu, He-Pin; Li, Qing; Luo, Chong-Guang

    2012-12-01

    Because the variation in chlorine isotopic abundances of naturally occurring chlorine bearing substances is significant, the IUPAC Inorganic Chemistry Division, Commission on Isotopic Abundances and Atomic Weights (CIAAW-IUPAC) decided that the uncertainty of atomic weight of chlorine (A(r)(Cl)) should be increased so that the implied range was related to terrestrial variability in 1999 (Coplen, T. B. Atomic weights of the elements 1999 (IUPAC Technical Report), Pure Appl. Chem.2001, 73(4), 667-683; and then, it emphasized that the standard atomic weights of ten elements including chlorine were not constants of nature but depend upon the physical, chemical, and nuclear history of the materials in 2009 (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396). According to the agreement by CIAAW that an atomic weight could be defined for one specified sample of terrestrial origin (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396), the absolute isotope ratios and atomic weight of chlorine in standard reference materials (NIST 975, NIST 975a, ISL 354) were accurately determined using the high-precision positive thermal ionization mass spectrometer (PTIMS)-Cs(2)Cl(+)-graphite method. After eliminating the weighing error caused from evaporation by designing a special weighing container and accurately determining the chlorine contents in two highly enriched Na(37)Cl and Na(35)Cl salts by the current constant coulometric titration, one series of gravimetric synthetic mixtures prepared from two highly enriched Na(37)Cl and Na(35)Cl salts was used to calibrate two thermal ionization mass spectrometers in two individual laboratories. The correction factors (i.e., K(37/35) = R(37/35meas)/R(37/35calc)) were obtained from five cycles of iterative calculations on the basis of calculated and determined R((37)Cl/(35)Cl) values in gravimetric synthetic mixtures. The absolute R((37)Cl/(35)Cl) ratios for NIST SRM 975, NIST 975a, and ISL 354 by the precise

  9. Updated Absolute Flux Calibration of the COS FUV Modes

    NASA Astrophysics Data System (ADS)

    Massa, D.; Ely, J.; Osten, R.; Penton, S.; Aloisi, A.; Bostroem, A.; Roman-Duval, J.; Proffitt, C.

    2014-03-01

    We present newly derived point source absolute flux calibrations for the COS FUV modes at both the original and second lifetime positions. The analysis includes observa- tions through the Primary Science Aperture (PSA) of the standard stars WD0308-565, GD71, WD1057+729 and WD0947+857 obtained as part of two calibration programs. Data were were obtained for all of the gratings at all of the original CENWAVE settings at both the original and second lifetime positions and for the G130M CENWAVE = 1222 at the second lifetime position. Data were also obtained with the FUVB segment for the G130M CENWAVE = 1055 and 1096 setting at the second lifetime position. We also present the derivation of L-flats that were used in processing the data and show that the internal consistency of the primary standards is 1%. The accuracy of the absolute flux calibrations over the UV are estimated to be 1-2% for the medium resolution gratings, and 2-3% over most of the wavelength range of the G140L grating, although the uncertainty can be as large as 5% or more at some G140L wavelengths. We note that these errors are all relative to the optical flux near the V band and small additional errors may be present due to inaccuracies in the V band calibration. In addition, these error estimates are for the time at which the flux calibration data were obtained; the accuracy of the flux calibration at other times can be affected by errors in the time dependent sensitivity (TDS) correction.

  10. On the accuracy of approximation of motion of a small celestial body by intermediate perturbed orbits calculated on the basis of three position vectors and three observations

    NASA Astrophysics Data System (ADS)

    Shefer, V. A.; Shefer, O. V.

    2016-05-01

    Intermediate perturbed orbits, which were proposed earlier by the first author and are calculated based on three position vectors and three measurements of angular coordinates of a small celestial body, are examined. Provided that the reference time interval encompassing the measurements is short, these orbits are close in the accuracy of approximation of actual motion to an orbit with fourth-order tangency. The shorter the reference time interval is, the better is the approximation. The laws of variation of the errors of methods for constructing such intermediate orbits with the length of the reference time interval are formulated. According to these laws, the rate of convergence of the methods to an exact solution in the process of shortening of the reference time interval is, in general, three orders of magnitude higher than that of conventional methods relying on an unperturbed Keplerian orbit. The considered orbits are among the most accurate of their class that is defined by the order of tangency. The obtained theoretical results are verified by numerical experiments on determining the orbit of 99942 Apophis.

  11. Absolute photoacoustic thermometry in deep tissue.

    PubMed

    Yao, Junjie; Ke, Haixin; Tai, Stephen; Zhou, Yong; Wang, Lihong V

    2013-12-15

    Photoacoustic thermography is a promising tool for temperature measurement in deep tissue. Here we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to correct for in deep tissue. To validate our method, absolute temperatures of blood-filled tubes embedded ~9 mm deep in chicken tissue were measured in a biologically relevant range from 28°C to 46°C. The temperature measurement accuracy was ~0.6°C. The results suggest that our method can be potentially used for absolute temperature monitoring in deep tissue during thermotherapy.

  12. Accuracy of the Residual Delay Absolute Phase Algorithm

    NASA Technical Reports Server (NTRS)

    Imel, D. A.

    1996-01-01

    Interferometric synthetic aperture radar (IFSAR) has become a useful technology for producing high-quality topographic maps. These measurements are required to reconstruct the three-dimensional coordinate of a point in an IFSAR image: the range, azimuth and elevation. The first is obtained by timing the return of the radar pulse, the second by measuring the doppler shift, and the last by measuring the phase difference between the signals received at two displaced antennae.

  13. Integrated Navigation System Design for Micro Planetary Rovers: Comparison of Absolute Heading Estimation Algorithms and Nonlinear Filtering.

    PubMed

    Ilyas, Muhammad; Hong, Beomjin; Cho, Kuk; Baeg, Seung-Ho; Park, Sangdeok

    2016-05-23

    This paper provides algorithms to fuse relative and absolute microelectromechanical systems (MEMS) navigation sensors, suitable for micro planetary rovers, to provide a more accurate estimation of navigation information, specifically, attitude and position. Planetary rovers have extremely slow speed (~1 cm/s) and lack conventional navigation sensors/systems, hence the general methods of terrestrial navigation may not be applicable to these applications. While relative attitude and position can be tracked in a way similar to those for ground robots, absolute navigation information is hard to achieve on a remote celestial body, like Moon or Mars, in contrast to terrestrial applications. In this study, two absolute attitude estimation algorithms were developed and compared for accuracy and robustness. The estimated absolute attitude was fused with the relative attitude sensors in a framework of nonlinear filters. The nonlinear Extended Kalman filter (EKF) and Unscented Kalman filter (UKF) were compared in pursuit of better accuracy and reliability in this nonlinear estimation problem, using only on-board low cost MEMS sensors. Experimental results confirmed the viability of the proposed algorithms and the sensor suite, for low cost and low weight micro planetary rovers. It is demonstrated that integrating the relative and absolute navigation MEMS sensors reduces the navigation errors to the desired level.

  14. Integrated Navigation System Design for Micro Planetary Rovers: Comparison of Absolute Heading Estimation Algorithms and Nonlinear Filtering

    PubMed Central

    Ilyas, Muhammad; Hong, Beomjin; Cho, Kuk; Baeg, Seung-Ho; Park, Sangdeok

    2016-01-01

    This paper provides algorithms to fuse relative and absolute microelectromechanical systems (MEMS) navigation sensors, suitable for micro planetary rovers, to provide a more accurate estimation of navigation information, specifically, attitude and position. Planetary rovers have extremely slow speed (~1 cm/s) and lack conventional navigation sensors/systems, hence the general methods of terrestrial navigation may not be applicable to these applications. While relative attitude and position can be tracked in a way similar to those for ground robots, absolute navigation information is hard to achieve on a remote celestial body, like Moon or Mars, in contrast to terrestrial applications. In this study, two absolute attitude estimation algorithms were developed and compared for accuracy and robustness. The estimated absolute attitude was fused with the relative attitude sensors in a framework of nonlinear filters. The nonlinear Extended Kalman filter (EKF) and Unscented Kalman filter (UKF) were compared in pursuit of better accuracy and reliability in this nonlinear estimation problem, using only on-board low cost MEMS sensors. Experimental results confirmed the viability of the proposed algorithms and the sensor suite, for low cost and low weight micro planetary rovers. It is demonstrated that integrating the relative and absolute navigation MEMS sensors reduces the navigation errors to the desired level. PMID:27223293

  15. Integrated Navigation System Design for Micro Planetary Rovers: Comparison of Absolute Heading Estimation Algorithms and Nonlinear Filtering.

    PubMed

    Ilyas, Muhammad; Hong, Beomjin; Cho, Kuk; Baeg, Seung-Ho; Park, Sangdeok

    2016-01-01

    This paper provides algorithms to fuse relative and absolute microelectromechanical systems (MEMS) navigation sensors, suitable for micro planetary rovers, to provide a more accurate estimation of navigation information, specifically, attitude and position. Planetary rovers have extremely slow speed (~1 cm/s) and lack conventional navigation sensors/systems, hence the general methods of terrestrial navigation may not be applicable to these applications. While relative attitude and position can be tracked in a way similar to those for ground robots, absolute navigation information is hard to achieve on a remote celestial body, like Moon or Mars, in contrast to terrestrial applications. In this study, two absolute attitude estimation algorithms were developed and compared for accuracy and robustness. The estimated absolute attitude was fused with the relative attitude sensors in a framework of nonlinear filters. The nonlinear Extended Kalman filter (EKF) and Unscented Kalman filter (UKF) were compared in pursuit of better accuracy and reliability in this nonlinear estimation problem, using only on-board low cost MEMS sensors. Experimental results confirmed the viability of the proposed algorithms and the sensor suite, for low cost and low weight micro planetary rovers. It is demonstrated that integrating the relative and absolute navigation MEMS sensors reduces the navigation errors to the desired level. PMID:27223293

  16. The effects of domain knowledge on metacomprehension accuracy.

    PubMed

    Griffin, Thomas D; Jee, Benjamin D; Wiley, Jennifer

    2009-10-01

    In the present research, we examined the relationship between readers' domain knowledge and their ability to judge their comprehension of novel domain-related material. Participants with varying degrees of baseball knowledge read five texts on baseball-related topics and five texts on non-baseball-related topics, predicted their performance, and completed tests for each text. Baseball knowledge was positively related to absolute accuracy within the baseball domain but was unrelated to relative accuracy within the baseball domain. Also, the readers showed a general underconfidence bias, but the bias was less extreme for higher knowledge readers. The results challenge common assumptions that experts' metacognitive judgments are less accurate than novices'. Results involving topic familiarity ratings and a no-reading control group suggest that higher knowledge readers are not more likely to ignore text-specific cues in favor of a domain familiarity heuristic, but they do appear to make more effective use of domain familiarity in predicting absolute performance levels.

  17. Issues in Absolute Spectral Radiometric Calibration: Intercomparison of Eight Sources

    NASA Technical Reports Server (NTRS)

    Goetz, Alexander F. H.; Kindel, Bruce; Pilewskie, Peter

    1998-01-01

    The application of atmospheric models to AVIRIS and other spectral imaging data to derive surface reflectance requires that the sensor output be calibrated to absolute radiance. Uncertainties in absolute calibration are to be expected, and claims of 92% accuracy have been published. Measurements of accurate surface albedos and cloud absorption to be used in radiative balance calculations depend critically on knowing the absolute spectral-radiometric response of the sensor. The Earth Observing System project is implementing a rigorous program of absolute radiometric calibration for all optical sensors. Since a number of imaging instruments that provide output in terms of absolute radiance are calibrated at different sites, it is important to determine the errors that can be expected among calibration sites. Another question exists about the errors in the absolute knowledge of the exoatmospheric spectral solar irradiance.

  18. Climate Absolute Radiance and Refractivity Observatory (CLARREO)

    NASA Technical Reports Server (NTRS)

    Leckey, John P.

    2015-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a mission, led and developed by NASA, that will measure a variety of climate variables with an unprecedented accuracy to quantify and attribute climate change. CLARREO consists of three separate instruments: an infrared (IR) spectrometer, a reflected solar (RS) spectrometer, and a radio occultation (RO) instrument. The mission will contain orbiting radiometers with sufficient accuracy, including on orbit verification, to calibrate other space-based instrumentation, increasing their respective accuracy by as much as an order of magnitude. The IR spectrometer is a Fourier Transform spectrometer (FTS) working in the 5 to 50 microns wavelength region with a goal of 0.1 K (k = 3) accuracy. The FTS will achieve this accuracy using phase change cells to verify thermistor accuracy and heated halos to verify blackbody emissivity, both on orbit. The RS spectrometer will measure the reflectance of the atmosphere in the 0.32 to 2.3 microns wavelength region with an accuracy of 0.3% (k = 2). The status of the instrumentation packages and potential mission options will be presented.

  19. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  20. Absolute and relative dosimetry for ELIMED

    SciTech Connect

    Cirrone, G. A. P.; Schillaci, F.; Scuderi, V.; Cuttone, G.; Candiano, G.; Musumarra, A.; Pisciotta, P.; Romano, F.; Carpinelli, M.; Presti, D. Lo; Raffaele, L.; Tramontana, A.; Cirio, R.; Sacchi, R.; Monaco, V.; Marchetto, F.; Giordanengo, S.

    2013-07-26

    The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

  1. An All Fiber White Light Interferometric Absolute Temperature Measurement System

    PubMed Central

    Kim, Jeonggon Harrison

    2008-01-01

    Recently the author of this article proposed a new signal processing algorithm for an all fiber white light interferometer. In this article, an all fiber white light interferometric absolute temperature measurement system is presented using the previously proposed signal processing algorithm. Stability and absolute temperature measurement were demonstrated. These two tests demonstrated the feasibility of absolute temperature measurement with an accuracy of 0.015 fringe and 0.0005 fringe, respectively. A hysteresis test from 373K to 873K was also presented. Finally, robustness of the sensor system towards laser diode temperature drift, AFMZI temperature drift and PZT non-linearity was demonstrated.

  2. Measurement of Disintegration Rates and Absolute {gamma}-ray Intensities

    SciTech Connect

    DeVries, Daniel J.; Griffin, Henry C.

    2006-03-13

    The majority of practical radioactive materials decay by modes that include {gamma}-ray emission. For questions of 'how much' or 'how pure', one must know the absolute intensities of the major radiations. We are using liquid scintillation counting (LSC) to measurements of disintegration rates, coupled with {gamma}-ray spectroscopy to measure absolute {gamma}-ray emission probabilities. Described is a study of the 227Th chain yielding absolute {gamma}-ray intensities with {approx}0.5% accuracy and information on LSC efficiencies.

  3. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  4. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  5. Accuracy Assessment of Mobile Mapping Point Clouds Using the Existing Environment as Terrestrial Reference

    NASA Astrophysics Data System (ADS)

    Hofmann, S.; Brenner, C.

    2016-06-01

    Mobile mapping data is widely used in various applications, what makes it especially important for data users to get a statistically verified quality statement on the geometric accuracy of the acquired point clouds or its processed products. The accuracy of point clouds can be divided into an absolute and a relative quality, where the absolute quality describes the position of the point cloud in a world coordinate system such as WGS84 or UTM, whereas the relative accuracy describes the accuracy within the point cloud itself. Furthermore, the quality of processed products such as segmented features depends on the global accuracy of the point cloud but mainly on the quality of the processing steps. Several data sources with different characteristics and quality can be thought of as potential reference data, such as cadastral maps, orthophoto, artificial control objects or terrestrial surveys using a total station. In this work a test field in a selected residential area was acquired as reference data in a terrestrial survey using a total station. In order to reach high accuracy the stationing of the total station was based on a newly made geodetic network with a local accuracy of less than 3 mm. The global position of the network was determined using a long time GNSS survey reaching an accuracy of 8 mm. Based on this geodetic network a 3D test field with facades and street profiles was measured with a total station, each point with a two-dimensional position and altitude. In addition, the surface of poles of street lights, traffic signs and trees was acquired using the scanning mode of the total station. Comparing this reference data to the acquired mobile mapping point clouds of several measurement campaigns a detailed quality statement on the accuracy of the point cloud data is made. Additionally, the advantages and disadvantages of the described reference data source concerning availability, cost, accuracy and applicability are discussed.

  6. Absolute configuration of isovouacapenol C

    PubMed Central

    Fun, Hoong-Kun; Yodsaoue, Orapun; Karalai, Chatchanok; Chantrapromma, Suchada

    2010-01-01

    The title compound, C27H34O5 {systematic name: (4aR,5R,6R,6aS,7R,11aS,11bR)-4a,6-dihy­droxy-4,4,7,11b-tetra­methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-5-yl benzoate}, is a cassane furan­oditerpene, which was isolated from the roots of Caesalpinia pulcherrima. The three cyclo­hexane rings are trans fused: two of these are in chair conformations with the third in a twisted half-chair conformation, whereas the furan ring is almost planar (r.m.s. deviation = 0.003 Å). An intra­molecular C—H⋯O inter­action generates an S(6) ring. The absolute configurations of the stereogenic centres at positions 4a, 5, 6, 6a, 7, 11a and 11b are R, R, R, S, R, S and R, respectively. In the crystal, mol­ecules are linked into infinite chains along [010] by O—H⋯O hydrogen bonds. C⋯O [3.306 (2)–3.347 (2) Å] short contacts and C—H⋯π inter­actions also occur. PMID:21588364

  7. Accuracy of the VITEK® 2 system for a rapid and direct identification and susceptibility testing of Gramnegative rods and Gram-positive cocci in blood samples.

    PubMed

    Nimer, N A; Al-Saa'da, R J; Abuelaish, O

    2016-06-15

    The performance of the VITEK® 2 system for direct rapid identification and antimicrobial susceptibility testing of the bacteria responsible for blood infections was determined. The isolates studied included 166 Gram-negative rods and 74 Gram-positive cocci from inpatients. Specially treated monomicrobial samples from positive blood culture bottles were directly inoculated into the VITEK 2 system and the results were compared with those from cards inoculated with standardized bacterial suspensions. Compared with the standard method, 95.8% of Gram-negative rods were correctly identified by VITEK 2 and the overall level of agreement between the two methods in susceptibility testing was 92.0%. For Gram-positive bacteria, 89.2% were correctly identified by VITEK 2 and susceptibility testing revealed an overall agreement rate of 91.3%. These results suggest that VITEK 2 cards inoculated with fluids sampled directly from positive blood culture bottles are suitable for speedy identification and susceptibility testing of Gram-negative bacilli and Gram-positive cocci.

  8. Toward robust deconvolution of pass-through paleomagnetic measurements: new tool to estimate magnetometer sensor response and laser interferometry of sample positioning accuracy

    NASA Astrophysics Data System (ADS)

    Oda, Hirokuni; Xuan, Chuang; Yamamoto, Yuhji

    2016-07-01

    Pass-through superconducting rock magnetometers (SRM) offer rapid and high-precision remanence measurements for continuous samples that are essential for modern paleomagnetism studies. However, continuous SRM measurements are inevitably smoothed and distorted due to the convolution effect of SRM sensor response. Deconvolution is necessary to restore accurate magnetization from pass-through SRM data, and robust deconvolution requires reliable estimate of SRM sensor response as well as understanding of uncertainties associated with the SRM measurement system. In this paper, we use the SRM at Kochi Core Center (KCC), Japan, as an example to introduce new tool and procedure for accurate and efficient estimate of SRM sensor response. To quantify uncertainties associated with the SRM measurement due to track positioning errors and test their effects on deconvolution, we employed laser interferometry for precise monitoring of track positions both with and without placing a u-channel sample on the SRM tray. The acquired KCC SRM sensor response shows significant cross-term of Z-axis magnetization on the X-axis pick-up coil and full widths of ~46-54 mm at half-maximum response for the three pick-up coils, which are significantly narrower than those (~73-80 mm) for the liquid He-free SRM at Oregon State University. Laser interferometry measurements on the KCC SRM tracking system indicate positioning uncertainties of ~0.1-0.2 and ~0.5 mm for tracking with and without u-channel sample on the tray, respectively. Positioning errors appear to have reproducible components of up to ~0.5 mm possibly due to patterns or damages on tray surface or rope used for the tracking system. Deconvolution of 50,000 simulated measurement data with realistic error introduced based on the position uncertainties indicates that although the SRM tracking system has recognizable positioning uncertainties, they do not significantly debilitate the use of deconvolution to accurately restore high

  9. An improved generalized Newton method for absolute value equations.

    PubMed

    Feng, Jingmei; Liu, Sanyang

    2016-01-01

    In this paper, we suggest and analyze an improved generalized Newton method for solving the NP-hard absolute value equations [Formula: see text] when the singular values of A exceed 1. We show that the global and local quadratic convergence of the proposed method. Numerical experiments show the efficiency of the method and the high accuracy of calculation. PMID:27462490

  10. Temporal Dynamics of Microbial Rhodopsin Fluorescence Reports Absolute Membrane Voltage

    PubMed Central

    Hou, Jennifer H.; Venkatachalam, Veena; Cohen, Adam E.

    2014-01-01

    Plasma membrane voltage is a fundamentally important property of a living cell; its value is tightly coupled to membrane transport, the dynamics of transmembrane proteins, and to intercellular communication. Accurate measurement of the membrane voltage could elucidate subtle changes in cellular physiology, but existing genetically encoded fluorescent voltage reporters are better at reporting relative changes than absolute numbers. We developed an Archaerhodopsin-based fluorescent voltage sensor whose time-domain response to a stepwise change in illumination encodes the absolute membrane voltage. We validated this sensor in human embryonic kidney cells. Measurements were robust to variation in imaging parameters and in gene expression levels, and reported voltage with an absolute accuracy of 10 mV. With further improvements in membrane trafficking and signal amplitude, time-domain encoding of absolute voltage could be applied to investigate many important and previously intractable bioelectric phenomena. PMID:24507604

  11. Singular perturbation of absolute stability.

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1972-01-01

    It was previously shown (author, 1969) that the regions of absolute stability in the parameter space can be determined when the parameters appear on the right-hand side of the system equations, i.e., the regular case. Here, the effect on absolute stability of a small parameter attached to higher derivatives in the equations (the singular case) is studied. The Lur'e-Postnikov class of nonlinear systems is considered.

  12. Map accuracy

    USGS Publications Warehouse

    ,

    1981-01-01

    An inaccurate map is not a reliable map. "X" may mark the spot where the treasure is buried, but unless the seeker can locate "X" in relation to known landmarks or positions, the map is not very useful.

  13. Enhancing Positioning Accuracy in Urban Terrain by Fusing Data from a GPS Receiver, Inertial Sensors, Stereo-Camera and Digital Maps for Pedestrian Navigation

    PubMed Central

    Przemyslaw, Baranski; Pawel, Strumillo

    2012-01-01

    The paper presents an algorithm for estimating a pedestrian location in an urban environment. The algorithm is based on the particle filter and uses different data sources: a GPS receiver, inertial sensors, probability maps and a stereo camera. Inertial sensors are used to estimate a relative displacement of a pedestrian. A gyroscope estimates a change in the heading direction. An accelerometer is used to count a pedestrian's steps and their lengths. The so-called probability maps help to limit GPS inaccuracy by imposing constraints on pedestrian kinematics, e.g., it is assumed that a pedestrian cannot cross buildings, fences etc. This limits position inaccuracy to ca. 10 m. Incorporation of depth estimates derived from a stereo camera that are compared to the 3D model of an environment has enabled further reduction of positioning errors. As a result, for 90% of the time, the algorithm is able to estimate a pedestrian location with an error smaller than 2 m, compared to an error of 6.5 m for a navigation based solely on GPS. PMID:22969321

  14. SU-E-P-54: Evaluation of the Accuracy and Precision of IGPS-O X-Ray Image-Guided Positioning System by Comparison with On-Board Imager Cone-Beam Computed Tomography

    SciTech Connect

    Zhang, D; Wang, W; Jiang, B; Fu, D

    2015-06-15

    Purpose: The purpose of this study is to assess the positioning accuracy and precision of IGPS-O system which is a novel radiographic kilo-voltage x-ray image-guided positioning system developed for clinical IGRT applications. Methods: IGPS-O x-ray image-guided positioning system consists of two oblique sets of radiographic kilo-voltage x-ray projecting and imaging devices which were equiped on the ground and ceiling of treatment room. This system can determine the positioning error in the form of three translations and three rotations according to the registration of two X-ray images acquired online and the planning CT image. An anthropomorphic head phantom and an anthropomorphic thorax phantom were used for this study. The phantom was set up on the treatment table with correct position and various “planned” setup errors. Both IGPS-O x-ray image-guided positioning system and the commercial On-board Imager Cone-beam Computed Tomography (OBI CBCT) were used to obtain the setup errors of the phantom. Difference of the Result between the two image-guided positioning systems were computed and analyzed. Results: The setup errors measured by IGPS-O x-ray image-guided positioning system and the OBI CBCT system showed a general agreement, the means and standard errors of the discrepancies between the two systems in the left-right, anterior-posterior, superior-inferior directions were −0.13±0.09mm, 0.03±0.25mm, 0.04±0.31mm, respectively. The maximum difference was only 0.51mm in all the directions and the angular discrepancy was 0.3±0.5° between the two systems. Conclusion: The spatial and angular discrepancies between IGPS-O system and OBI CBCT for setup error correction was minimal. There is a general agreement between the two positioning system. IGPS-O x-ray image-guided positioning system can achieve as good accuracy as CBCT and can be used in the clinical IGRT applications.

  15. Effect of positioning on the accuracy of decision making of association football top-class referees and assistant referees during competitive matches.

    PubMed

    Mallo, Javier; Frutos, Pablo Gonzalez; Juárez, Daniel; Navarro, Enrique

    2012-01-01

    The aim of this study was to examine the effect of positioning on the correctness of decision making of top-class referees and assistant referees during international games. Match analyses were carried out during the Fédération Internationale de Football Association (FIFA) Confederations Cup 2009 and 380 foul play incidents and 165 offside situations were examined. The error percentage for the referees when indicating the incidents averaged 14%. The lowest error percentage occurred in the central area of the field, where the collaboration of the assistant referee is limited, and was achieved when indicating the incidents from a distance of 11-15 m, whereas this percentage peaked (23%) in the last 15-min match period. The error rate for the assistant referees was 13%. Distance of the assistant referee to the offside line did not have an impact on the quality of the offside decision. The risk of making incorrect decisions was reduced when the assistant referees viewed the offside situations from an angle between 46 and 60°. Incorrect offside decisions occurred twice as often in the second as in the first half of the games. Perceptual-cognitive training sessions specific to the requirements of the game should be implemented in the weekly schedule of football officials to reduce the overall error rate. PMID:22867266

  16. Absolute flux scale for radioastronomy

    SciTech Connect

    Ivanov, V.P.; Stankevich, K.S.

    1986-07-01

    The authors propose and provide support for a new absolute flux scale for radio astronomy, which is not encumbered with the inadequacies of the previous scales. In constructing it the method of relative spectra was used (a powerful tool for choosing reference spectra). A review is given of previous flux scales. The authors compare the AIS scale with the scale they propose. Both scales are based on absolute measurements by the ''artificial moon'' method, and they are practically coincident in the range from 0.96 to 6 GHz. At frequencies above 6 GHz, 0.96 GHz, the AIS scale is overestimated because of incorrect extrapolation of the spectra of the primary and secondary standards. The major results which have emerged from this review of absolute scales in radio astronomy are summarized.

  17. Accuracy evaluation of 3D lidar data from small UAV

    NASA Astrophysics Data System (ADS)

    Tulldahl, H. M.; Bissmarck, Fredrik; Larsson, Hâkan; Grönwall, Christina; Tolt, Gustav

    2015-10-01

    A UAV (Unmanned Aerial Vehicle) with an integrated lidar can be an efficient system for collection of high-resolution and accurate three-dimensional (3D) data. In this paper we evaluate the accuracy of a system consisting of a lidar sensor on a small UAV. High geometric accuracy in the produced point cloud is a fundamental qualification for detection and recognition of objects in a single-flight dataset as well as for change detection using two or several data collections over the same scene. Our work presented here has two purposes: first to relate the point cloud accuracy to data processing parameters and second, to examine the influence on accuracy from the UAV platform parameters. In our work, the accuracy is numerically quantified as local surface smoothness on planar surfaces, and as distance and relative height accuracy using data from a terrestrial laser scanner as reference. The UAV lidar system used is the Velodyne HDL-32E lidar on a multirotor UAV with a total weight of 7 kg. For processing of data into a geographically referenced point cloud, positioning and orientation of the lidar sensor is based on inertial navigation system (INS) data combined with lidar data. The combination of INS and lidar data is achieved in a dynamic calibration process that minimizes the navigation errors in six degrees of freedom, namely the errors of the absolute position (x, y, z) and the orientation (pitch, roll, yaw) measured by GPS/INS. Our results show that low-cost and light-weight MEMS based (microelectromechanical systems) INS equipment with a dynamic calibration process can obtain significantly improved accuracy compared to processing based solely on INS data.

  18. Absolute Radiometric Calibration of EUNIS-06

    NASA Technical Reports Server (NTRS)

    Thomas, R. J.; Rabin, D. M.; Kent, B. J.; Paustian, W.

    2007-01-01

    The Extreme-Ultraviolet Normal-Incidence Spectrometer (EUNIS) is a soundingrocket payload that obtains imaged high-resolution spectra of individual solar features, providing information about the Sun's corona and upper transition region. Shortly after its successful initial flight last year, a complete end-to-end calibration was carried out to determine the instrument's absolute radiometric response over its Longwave bandpass of 300 - 370A. The measurements were done at the Rutherford-Appleton Laboratory (RAL) in England, using the same vacuum facility and EUV radiation source used in the pre-flight calibrations of both SOHO/CDS and Hinode/EIS, as well as in three post-flight calibrations of our SERTS sounding rocket payload, the precursor to EUNIS. The unique radiation source provided by the Physikalisch-Technische Bundesanstalt (PTB) had been calibrated to an absolute accuracy of 7% (l-sigma) at 12 wavelengths covering our bandpass directly against the Berlin electron storage ring BESSY, which is itself a primary radiometric source standard. Scans of the EUNIS aperture were made to determine the instrument's absolute spectral sensitivity to +- 25%, considering all sources of error, and demonstrate that EUNIS-06 was the most sensitive solar E W spectrometer yet flown. The results will be matched against prior calibrations which relied on combining measurements of individual optical components, and on comparisons with theoretically predicted 'insensitive' line ratios. Coordinated observations were made during the EUNIS-06 flight by SOHO/CDS and EIT that will allow re-calibrations of those instruments as well. In addition, future EUNIS flights will provide similar calibration updates for TRACE, Hinode/EIS, and STEREO/SECCHI/EUVI.

  19. Assessment of the accuracy of infrared and electromagnetic navigation using an industrial robot: Which factors are influencing the accuracy of navigation?

    PubMed

    Liodakis, Emmanouil; Chu, Kongfai; Westphal, Ralf; Krettek, Christian; Citak, Musa; Gosling, Thomas; Kenawey, Mohamed

    2011-10-01

    Our objectives were to detect factors that influence the accuracy of surgical navigation (magnitude of deformity, plane of deformity, position of the navigation bases) and compare the accuracy of infrared with electromagnetic navigation. Human cadaveric femora were used. A robot connected with a computer moved one of the bony fragments in a desired direction. The bases of the infrared navigation (BrainLab) and the receivers of the electromagnetic device (Fastrak-Pohlemus) were attached to the proximal and distal parts of the bone. For the first part of the study, deformities were classified in eight groups (e.g., 0 to 5(°)). For the second part, the bases were initially placed near the osteotomy and then far away. The mean absolute differences between both navigation system measurements and the robotic angles were significantly affected by the magnitude of angulation with better accuracy for smaller angulations (p < 0.001). The accuracy of infrared navigation was significantly better in the frontal and sagittal plane. Changing the position of the navigation bases near and far away from the deformity apex had no significant effect on the accuracy of infrared navigation; however, it influenced the accuracy of electromagnetic navigation in the frontal plane (p < 0.001). In conclusion, the use of infrared navigation systems for corrections of small angulation-deformities in the frontal or sagittal plane provides the most accurate results, irrespectively from the positioning of the navigation bases.

  20. Micron Accurate Absolute Ranging System: Range Extension

    NASA Technical Reports Server (NTRS)

    Smalley, Larry L.; Smith, Kely L.

    1999-01-01

    The purpose of this research is to investigate Fresnel diffraction as a means of obtaining absolute distance measurements with micron or greater accuracy. It is believed that such a system would prove useful to the Next Generation Space Telescope (NGST) as a non-intrusive, non-contact measuring system for use with secondary concentrator station-keeping systems. The present research attempts to validate past experiments and develop ways to apply the phenomena of Fresnel diffraction to micron accurate measurement. This report discusses past research on the phenomena, and the basis of the use Fresnel diffraction distance metrology. The apparatus used in the recent investigations, experimental procedures used, preliminary results are discussed in detail. Continued research and equipment requirements on the extension of the effective range of the Fresnel diffraction systems is also described.

  1. Swarm's Absolute Scalar Magnetometer metrological performances

    NASA Astrophysics Data System (ADS)

    Leger, J.; Fratter, I.; Bertrand, F.; Jager, T.; Morales, S.

    2012-12-01

    The Absolute Scalar Magnetometer (ASM) has been developed for the ESA Earth Observation Swarm mission, planned for launch in November 2012. As its Overhauser magnetometers forerunners flown on Oersted and Champ satellites, it will deliver high resolution scalar measurements for the in-flight calibration of the Vector Field Magnetometer manufactured by the Danish Technical University. Latest results of the ground tests carried out to fully characterize all parameters that may affect its accuracy, both at instrument and satellite level, will be presented. In addition to its baseline function, the ASM can be operated either at a much higher sampling rate (burst mode at 250 Hz) or in a dual mode where it also delivers vector field measurements as a by-product. The calibration procedure and the relevant vector performances will be discussed.

  2. Sentinel-2/MSI absolute calibration: first results

    NASA Astrophysics Data System (ADS)

    Lonjou, V.; Lachérade, S.; Fougnie, B.; Gamet, P.; Marcq, S.; Raynaud, J.-L.; Tremas, T.

    2015-10-01

    Sentinel-2 is an optical imaging mission devoted to the operational monitoring of land and coastal areas. It is developed in partnership between the European Commission and the European Space Agency. The Sentinel-2 mission is based on a satellites constellation deployed in polar sun-synchronous orbit. It will offer a unique combination of global coverage with a wide field of view (290km), a high revisit (5 days with two satellites), a high resolution (10m, 20m and 60m) and multi-spectral imagery (13 spectral bands in visible and shortwave infra-red domains). CNES is involved in the instrument commissioning in collaboration with ESA. This paper reviews all the techniques that will be used to insure an absolute calibration of the 13 spectral bands better than 5% (target 3%), and will present the first results if available. First, the nominal calibration technique, based on an on-board sun diffuser, is detailed. Then, we show how vicarious calibration methods based on acquisitions over natural targets (oceans, deserts, and Antarctica during winter) will be used to check and improve the accuracy of the absolute calibration coefficients. Finally, the verification scheme, exploiting photometer in-situ measurements over Lacrau plain, is described. A synthesis, including spectral coherence, inter-methods agreement and temporal evolution, will conclude the paper.

  3. Experimental results for absolute cylindrical wavefront testing

    NASA Astrophysics Data System (ADS)

    Reardon, Patrick J.; Alatawi, Ayshah

    2014-09-01

    Applications for Cylindrical and near-cylindrical surfaces are ever-increasing. However, fabrication of high quality cylindrical surfaces is limited by the difficulty of accurate and affordable metrology. Absolute testing of such surfaces represents a challenge to the optical testing community as cylindrical reference wavefronts are difficult to produce. In this paper, preliminary results for a new method of absolute testing of cylindrical wavefronts are presented. The method is based on the merging of the random ball test method with the fiber optic reference test. The random ball test assumes a large number of interferograms of a good quality sphere with errors that are statistically distributed such that the average of the errors goes to zero. The fiber optic reference test utilizes a specially processed optical fiber to provide a clean high quality reference wave from an incident line focus from the cylindrical wave under test. By taking measurements at different rotation and translations of the fiber, an analogous procedure can be employed to determine the quality of the converging cylindrical wavefront with high accuracy. This paper presents and discusses the results of recent tests of this method using a null optic formed by a COTS cylindrical lens and a free-form polished corrector element.

  4. Absolute Proper Motions of Southern Globular Clusters

    NASA Astrophysics Data System (ADS)

    Dinescu, D. I.; Girard, T. M.; van Altena, W. F.

    1996-05-01

    Our program involves the determination of absolute proper motions with respect to galaxies for a sample of globular clusters situated in the southern sky. The plates cover a 6(deg) x 6(deg) area and are taken with the 51-cm double astrograph at Cesco Observatory in El Leoncito, Argentina. We have developed special methods to deal with the modelling error of the plate transformation and we correct for magnitude equation using the cluster stars. This careful astrometric treatment leads to accuracies of from 0.5 to 1.0 mas/yr for the absolute proper motion of each cluster, depending primarily on the number of measurable cluster stars which in turn is related to the cluster's distance. Space velocities are then derived which, in association with metallicities, provide key information for the formation scenario of the Galaxy, i.e. accretion and/or dissipational collapse. Here we present results for NGC 1851, NGC 6752, NGC 6584, NGC 6362 and NGC 288.

  5. Comparison of Using Relative and Absolute PCV Corrections in Short Baseline GNSS Observation Processing

    NASA Astrophysics Data System (ADS)

    Dawidowicz, Karol

    2011-01-01

    GNSS antenna phase center variations (PCV) are defined as shifts in positions depending on the observed elevation angle and azimuth to the satellite. When identical antennae are used in relative measurement the phase center variations will cancel out, particularly over short baselines. When different antennae are used, even on short baselines, ignoring these phase center variations can lead to serious (up to 10 cm) vertical errors. The only way to avoid these errors, when mixing different antenna types, is by applying antenna phase center variation models in processing. Till the 6th November 2006, the International GNSS Service used relative phase center models for GNSS antenna receivers. Then absolute calibration models, developed by the company "Geo++", started to be used. These models involved significant differences on the scale of GNSS networks compared to the VLBI and SLR measurements. The differences were due to the lack of the GNSS satellite antenna calibration models. When this problem was sufficiently resolved, the IGS decided to switch from relative to absolute models for both satellites and receivers. This decision caused significant variations to the results of the GNSS network solutions. The aim of this paper is to study the height differences in short baseline GNSS observations processing when different calibration models are used. The analysis was done using GNSS data collected at short baselines moved with different receiver antennas. The results of calculations show, that switching from relative to absolute receiver antenna PCV models has a significant effect on GNSS network solutions, particularly in high accuracy applications.

  6. Global absolut gravity reference system as replacement of IGSN 71

    NASA Astrophysics Data System (ADS)

    Wilmes, Herbert; Wziontek, Hartmut; Falk, Reinhard

    2015-04-01

    The determination of precise gravity field parameters is of great importance in a period in which earth sciences are achieving the necessary accuracy to monitor and document global change processes. This is the reason why experts from geodesy and metrology joined in a successful cooperation to make absolute gravity observations traceable to SI quantities, to improve the metrological kilogram definition and to monitor mass movements and smallest height changes for geodetic and geophysical applications. The international gravity datum is still defined by the International Gravity Standardization Net adopted in 1971 (IGSN 71). The network is based upon pendulum and spring gravimeter observations taken in the 1950s and 60s supported by the early free fall absolute gravimeters. Its gravity values agreed in every case to better than 0.1 mGal. Today, more than 100 absolute gravimeters are in use worldwide. The series of repeated international comparisons confirms the traceability of absolute gravity measurements to SI quantities and confirm the degree of equivalence of the gravimeters in the order of a few µGal. For applications in geosciences where e.g. gravity changes over time need to be analyzed, the temporal stability of an absolute gravimeter is most important. Therefore, the proposition is made to replace the IGSN 71 by an up-to-date gravity reference system which is based upon repeated absolute gravimeter comparisons and a global network of well controlled gravity reference stations.

  7. Relativistic Absolutism in Moral Education.

    ERIC Educational Resources Information Center

    Vogt, W. Paul

    1982-01-01

    Discusses Emile Durkheim's "Moral Education: A Study in the Theory and Application of the Sociology of Education," which holds that morally healthy societies may vary in culture and organization but must possess absolute rules of moral behavior. Compares this moral theory with current theory and practice of American educators. (MJL)

  8. High angular resolution absolute intensity of the solar continuum from 1400 to 1790 A.

    NASA Technical Reports Server (NTRS)

    Brueckner, G. E.; Moe, O. K.

    1972-01-01

    Absolute intensities of the solar UV continuum from 1400 to 1790 A have been measured from rocket spectra taken on August 13, 1970. The spectra had an angular resolution of 2 arc sec by 1 arc min, and the pointing accuracy of the instrument was plus or minus 2 arc sec. This permits us to study the center-to-limb variation of the intensity with a spatial resolution of 2 arc sec. Four positions on the solar disk have been studied corresponding to values of cos theta = 0.12, 0.22, 0.28 and 0.72, where theta is the heliocentric position angle. The measurements give higher values for the intensity than recent photoelectric measurement, but are in good agreement with the intensities of Widing et al.

  9. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  10. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate.

  11. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate. PMID:11262641

  12. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  13. Classification images predict absolute efficiency.

    PubMed

    Murray, Richard F; Bennett, Patrick J; Sekuler, Allison B

    2005-02-24

    How well do classification images characterize human observers' strategies in perceptual tasks? We show mathematically that from the classification image of a noisy linear observer, it is possible to recover the observer's absolute efficiency. If we could similarly predict human observers' performance from their classification images, this would suggest that the linear model that underlies use of the classification image method is adequate over the small range of stimuli typically encountered in a classification image experiment, and that a classification image captures most important aspects of human observers' performance over this range. In a contrast discrimination task and in a shape discrimination task, we found that observers' absolute efficiencies were generally well predicted by their classification images, although consistently slightly (approximately 13%) higher than predicted. We consider whether a number of plausible nonlinearities can account for the slight under prediction, and of these we find that only a form of phase uncertainty can account for the discrepancy.

  14. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  15. Parallaxes and Proper Motions of QSOs: A Test of Astrometric Precision and Accuracy

    NASA Astrophysics Data System (ADS)

    Harris, Hugh C.; Dahn, Conard C.; Zacharias, Norbert; Canzian, Blaise; Guetter, Harry H.; Levine, Stephen E.; Luginbuhl, Christian B.; Monet, Alice K. B.; Monet, David G.; Pier, Jeffrey R.; Stone, Ronald C.; Subasavage, John P.; Tilleman, Trudy; Walker, Richard L.; Johnston, Kenneth J.

    2016-11-01

    Optical astrometry of 12 fields containing quasi-stellar objects (QSOs) is presented. The targets are radio sources in the International Celestial Reference Frame with accurate radio positions that also have optical counterparts. The data are used to test several quantities: the internal precision of the relative optical astrometry, the relative parallaxes and proper motions, the procedures to correct from relative to absolute parallax and proper motion, the accuracy of the absolute parallaxes and proper motions, and the stability of the optical photocenters for these optically variable QSOs. For these 12 fields, the mean error in absolute parallax is 0.38 mas and the mean error in each coordinate of absolute proper motion is 1.1 mas yr‑1. The results yield a mean absolute parallax of ‑0.03 ± 0.11 mas. For 11 targets, we find no significant systematic motions of the photocenters at the level of 1–2 mas over the 10 years of this study; for one BL Lac object, we find a possible motion of 4 mas correlated with its brightness.

  16. Strategy for the absolute neutron emission measurement on ITER.

    PubMed

    Sasao, M; Bertalot, L; Ishikawa, M; Popovichev, S

    2010-10-01

    Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 10(10) n/s (neutron/second) for DT and 10(8) n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

  17. Strategy for the absolute neutron emission measurement on ITER

    SciTech Connect

    Sasao, M.; Bertalot, L.; Ishikawa, M.; Popovichev, S.

    2010-10-15

    Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 10{sup 10} n/s (neutron/second) for DT and 10{sup 8} n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

  18. Familial Aggregation of Absolute Pitch

    PubMed Central

    Baharloo, Siamak; Service, Susan K.; Risch, Neil; Gitschier, Jane; Freimer, Nelson B.

    2000-01-01

    Absolute pitch (AP) is a behavioral trait that is defined as the ability to identify the pitch of tones in the absence of a reference pitch. AP is an ideal phenotype for investigation of gene and environment interactions in the development of complex human behaviors. Individuals who score exceptionally well on formalized auditory tests of pitch perception are designated as “AP-1.” As described in this report, auditory testing of siblings of AP-1 probands and of a control sample indicates that AP-1 aggregates in families. The implications of this finding for the mapping of loci for AP-1 predisposition are discussed. PMID:10924408

  19. Development and Testing of a High-Precision Position and Attitude Measuring System for a Space Mechanism

    NASA Technical Reports Server (NTRS)

    Khanenya, Nikolay; Paciotti, Gabriel; Forzani, Eugenio; Blecha, Luc

    2016-01-01

    This paper describes a high-precision optical metrology system - a unique ground test equipment which was designed and implemented for simultaneous precise contactless measurements of 6 degrees-of-freedom (3 translational + 3 rotational) of a space mechanism end-effector [1] in a thermally controlled ISO 5 clean environment. The developed contactless method reconstructs both position and attitude of the specimen from three cross-sections measured by 2D distance sensors [2]. The cleanliness is preserved by the hermetic test chamber filled with high purity nitrogen. The specimen's temperature is controlled by the thermostat [7]. The developed method excludes errors caused by the thermal deformations and manufacturing inaccuracies of the test jig. Tests and simulations show that the measurement accuracy of an object absolute position is of 20 micron in in-plane measurement (XY) and about 50 micron out of plane (Z). The typical absolute attitude is determined with an accuracy better than 3 arcmin in rotation around X and Y and better than 10 arcmin in Z. The metrology system is able to determine relative position and movement with an accuracy one order of magnitude lower than the absolute accuracy. Typical relative displacement measurement accuracies are better than 1 micron in X and Y and about 2 micron in Z. Finally, the relative rotation can be measured with accuracy better than 20 arcsec in any direction.

  20. Absolute Gravity Datum in the Age of Cold Atom Gravimeters

    NASA Astrophysics Data System (ADS)

    Childers, V. A.; Eckl, M. C.

    2014-12-01

    The international gravity datum is defined today by the International Gravity Standardization Net of 1971 (IGSN-71). The data supporting this network was measured in the 1950s and 60s using pendulum and spring-based gravimeter ties (plus some new ballistic absolute meters) to replace the prior protocol of referencing all gravity values to the earlier Potsdam value. Since this time, gravimeter technology has advanced significantly with the development and refinement of the FG-5 (the current standard of the industry) and again with the soon-to-be-available cold atom interferometric absolute gravimeters. This latest development is anticipated to provide improvement in the range of two orders of magnitude as compared to the measurement accuracy of technology utilized to develop ISGN-71. In this presentation, we will explore how the IGSN-71 might best be "modernized" given today's requirements and available instruments and resources. The National Geodetic Survey (NGS), along with other relevant US Government agencies, is concerned about establishing gravity control to establish and maintain high order geodetic networks as part of the nation's essential infrastructure. The need to modernize the nation's geodetic infrastructure was highlighted in "Precise Geodetic Infrastructure, National Requirements for a Shared Resource" National Academy of Science, 2010. The NGS mission, as dictated by Congress, is to establish and maintain the National Spatial Reference System, which includes gravity measurements. Absolute gravimeters measure the total gravity field directly and do not involve ties to other measurements. Periodic "intercomparisons" of multiple absolute gravimeters at reference gravity sites are used to constrain the behavior of the instruments to ensure that each would yield reasonably similar measurements of the same location (i.e. yield a sufficiently consistent datum when measured in disparate locales). New atomic interferometric gravimeters promise a significant

  1. On the Error Sources in Absolute Individual Antenna Calibrations

    NASA Astrophysics Data System (ADS)

    Aerts, Wim; Baire, Quentin; Bilich, Andria; Bruyninx, Carine; Legrand, Juliette

    2013-04-01

    field) multi path errors, both during calibration and later on at the station, absolute sub-millimeter positioning with GPS is not (yet) possible. References [1] G. Wübbena, M. Schmitz, G. Boettcher, C. Schumann, "Absolute GNSS Antenna Calibration with a Robot: Repeatability of Phase Variations, Calibration of GLONASS and Determination of Carrier-to-Noise Pattern", International GNSS Service: Analysis Center workshop, 8-12 May 2006, Darmstadt, Germany. [2] P. Zeimetz, H. Kuhlmann, "On the Accuracy of Absolute GNSS Antenna Calibration and the Conception of a New Anechoic Chamber", FIG Working Week 2008, 14-19 June 2008, Stockholm, Sweden. [3] P. Zeimetz, H. Kuhlmann, L. Wanninger, V. Frevert, S. Schön and K. Strauch, "Ringversuch 2009", 7th GNSS-Antennen-Workshop, 19-20 March 2009, Dresden, Germany.

  2. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < ‑1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  3. Apparatus for absolute pressure measurement

    NASA Technical Reports Server (NTRS)

    Hecht, R. (Inventor)

    1969-01-01

    An absolute pressure sensor (e.g., the diaphragm of a capacitance manometer) was subjected to a superimposed potential to effectively reduce the mechanical stiffness of the sensor. This substantially increases the sensitivity of the sensor and is particularly useful in vacuum gauges. An oscillating component of the superimposed potential induced vibrations of the sensor. The phase of these vibrations with respect to that of the oscillating component was monitored, and served to initiate an automatic adjustment of the static component of the superimposed potential, so as to bring the sensor into resonance at the frequency of the oscillating component. This establishes a selected sensitivity for the sensor, since a definite relationship exists between resonant frequency and sensitivity.

  4. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < -1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  5. Measurement of Absolute Carbon Isotope Ratios: Mechanisms and Implications

    NASA Astrophysics Data System (ADS)

    Vogel, J. S.; Giacomo, J. A.; Dueker, S. R.

    2012-12-01

    An accelerator mass spectrometer (AMS) produced absolute isotope ratio measurements for 14C/13C as tested against >500 samples of NIST SRM-4990-C (OxII 14C standard) to an accuracy of 2.2±0.6‰ over a period of one year with measurements made to 1% counting statistics. The spectrometer is not maximized for 13C/12C, but measured ∂13C to 0.4±0.1‰ accuracy, with known methods for improvement. An AMS produces elemental anions from a sputter ion source and includes a charge-changing collision in a gas cell to isolate the rare 14C from the common isotopes and molecular isobars. Both these physical processes have been modeled to determine the parameters providing such absolute measures. Neutral resonant ionization in a cesium plasma produces mass-independent ionization, while velocity dependent charge-state distributions in gas collisions produce relative ion beam intensities that are linear in mass at specific collision energies. The mechanisms are not specific to carbon isotopes, but stand alone absolute IRMS (AIR-MS) instruments have not yet been made. Aside from the obvious applications in metrology, AIR-MS is particularly valuable in coupled separatory MS because no internal or external standards are required. Sample definition processes can be compared, even if no exact standard reference sample exists. Isotope dilution measurements do not require standards matching the dilution end-points and can be made over an extended, even extrapolated, range.

  6. a Portable Apparatus for Absolute Measurements of the Earth's Gravity.

    NASA Astrophysics Data System (ADS)

    Zumberge, Mark Andrew

    We have developed a new, portable apparatus for making absolute measurements of the acceleration due to the earth's gravity. We use the method of interferometrically determining the acceleration of a freely falling corner -cube prism. The falling object is surrounded by a chamber which is driven vertically inside a fixed vacuum chamber. This falling chamber is servoed to track the falling corner -cube to shield it from drag due to background gas. In addition, the drag-free falling chamber removes the need for a magnetic release, shields the falling object from electrostatic forces, and provides a means of both gently arresting the falling object and quickly returning it to its start position, to allow rapid acquisition of data. A synthesized long period isolation device reduces the noise due to seismic oscillations. A new type of Zeeman laser is used as the light source in the interferometer, and is compared with the wavelength of an iodine stabilized laser. The times of occurrence of 45 interference fringes are measured to within 0.2 nsec over a 20 cm drop and are fit to a quadratic by an on-line minicomputer. 150 drops can be made in ten minutes resulting in a value of g having a precision of 3 to 6 parts in 10('9). Systematic errors have been determined to be less than 5 parts in 10('9) through extensive tests. Three months of gravity data have been obtained with a reproducibility ranging from 5 to 10 parts in 10('9). The apparatus has been designed to be easily portable. Field measurements are planned for the immediate future. An accuracy of 6 parts in 10('9) corresponds to a height sensitivity of 2 cm. Vertical motions in the earth's crust and tectonic density changes that may precede earthquakes are to be investigated using this apparatus.

  7. Method and apparatus for two-dimensional absolute optical encoding

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B. (Inventor)

    2004-01-01

    This invention presents a two-dimensional absolute optical encoder and a method for determining position of an object in accordance with information from the encoder. The encoder of the present invention comprises a scale having a pattern being predetermined to indicate an absolute location on the scale, means for illuminating the scale, means for forming an image of the pattern; and detector means for outputting signals derived from the portion of the image of the pattern which lies within a field of view of the detector means, the field of view defining an image reference coordinate system, and analyzing means, receiving the signals from the detector means, for determining the absolute location of the object. There are two types of scale patterns presented in this invention: grid type and starfield type.

  8. Determination of absolute internal conversion coefficients using the SAGE spectrometer

    NASA Astrophysics Data System (ADS)

    Sorri, J.; Greenlees, P. T.; Papadakis, P.; Konki, J.; Cox, D. M.; Auranen, K.; Partanen, J.; Sandzelius, M.; Pakarinen, J.; Rahkila, P.; Uusitalo, J.; Herzberg, R.-D.; Smallcombe, J.; Davies, P. J.; Barton, C. J.; Jenkins, D. G.

    2016-03-01

    A non-reference based method to determine internal conversion coefficients using the SAGE spectrometer is carried out for transitions in the nuclei of 154Sm, 152Sm and 166Yb. The Normalised-Peak-to-Gamma method is in general an efficient tool to extract internal conversion coefficients. However, in many cases the required well-known reference transitions are not available. The data analysis steps required to determine absolute internal conversion coefficients with the SAGE spectrometer are presented. In addition, several background suppression methods are introduced and an example of how ancillary detectors can be used to select specific reaction products is given. The results obtained for ground-state band E2 transitions show that the absolute internal conversion coefficients can be extracted using the methods described with a reasonable accuracy. In some cases of less intense transitions only an upper limit for the internal conversion coefficient could be given.

  9. Absolute magnitude calibration using trigonometric parallax - Incomplete, spectroscopic samples

    NASA Technical Reports Server (NTRS)

    Ratnatunga, Kavan U.; Casertano, Stefano

    1991-01-01

    A new numerical algorithm is used to calibrate the absolute magnitude of spectroscopically selected stars from their observed trigonometric parallax. This procedure, based on maximum-likelihood estimation, can retrieve unbiased estimates of the intrinsic absolute magnitude and its dispersion even from incomplete samples suffering from selection biases in apparent magnitude and color. It can also make full use of low accuracy and negative parallaxes and incorporate censorship on reported parallax values. Accurate error estimates are derived for each of the fitted parameters. The algorithm allows an a posteriori check of whether the fitted model gives a good representation of the observations. The procedure is described in general and applied to both real and simulated data.

  10. Wavelength Calibration Accuracy for the STIS CCD and MAMA Modes

    NASA Astrophysics Data System (ADS)

    Pascucci, Ilaria; Hodge, Phil; Proffitt, Charles R.; Ayres, T.

    2011-03-01

    Two calibration programs were carried out to determine the accuracy of the wavelength solutions for the most used STIS CCD and MAMA modes after Servicing Mission 4. We report here on the analysis of this dataset and show that the STIS wavelength solution has not changed after SM4. We also show that a typical accuracy for the absolute wavelength zero-points is 0.1 pixels while the relative wavelength accuracy is 0.2 pixels.

  11. Frequency-domain analysis of absolute gravimeters

    NASA Astrophysics Data System (ADS)

    Svitlov, S.

    2012-12-01

    An absolute gravimeter is analysed as a linear time-invariant system in the frequency domain. Frequency responses of absolute gravimeters are derived analytically based on the propagation of the complex exponential signal through their linear measurement functions. Depending on the model of motion and the number of time-distance coordinates, an absolute gravimeter is considered as a second-order (three-level scheme) or third-order (multiple-level scheme) low-pass filter. It is shown that the behaviour of an atom absolute gravimeter in the frequency domain corresponds to that of the three-level corner-cube absolute gravimeter. Theoretical results are applied for evaluation of random and systematic measurement errors and optimization of an experiment. The developed theory agrees with known results of an absolute gravimeter analysis in the time and frequency domains and can be used for measurement uncertainty analyses, building of vibration-isolation systems and synthesis of digital filtering algorithms.

  12. Cryogenic absolute radiometers as laboratory irradiance standards, remote sensing detectors, and pyroheliometers

    NASA Technical Reports Server (NTRS)

    Foukal, Peter V.; Hoyt, C.; Kochling, H.; Miller, P.

    1990-01-01

    The dramatic improvement in heat diffusivity of pure Cu at liquid-He temperatures makes possible very important advances in the absolute accuracy, reproducibility, sensitivity, and time constant of cryogenic electrical substitution radiometers (ESRs), relative to conventional ESRs. The design and characterization of a table-top cryogenic ESR now available for detector calibration work to the 0.01-percent level of absolute accuracy under laser illumination is discussed. A sensitive cryogenic ESR recently delivered to the NIST for radiometric calibrations of black bodies is also described, along with the design and testing of a very fast cryogenic ESR developed for NASA remote-sensing studies of the earth's radiation budget.

  13. Assessing and Ensuring GOES-R Magnetometer Accuracy

    NASA Technical Reports Server (NTRS)

    Kronenwetter, Jeffrey; Carter, Delano R.; Todirita, Monica; Chu, Donald

    2016-01-01

    The GOES-R magnetometer accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma. To achieve this, the sensor itself has better than 1 nT accuracy. Because zero offset and scale factor drift over time, it is also necessary to perform annual calibration maneuvers. To predict performance, we used covariance analysis and attempted to corroborate it with simulations. Although not perfect, the two generally agree and show the expected behaviors. With the annual calibration regimen, these predictions suggest that the magnetometers will meet their accuracy requirements.

  14. Assessing and Ensuring GOES-R Magnetometer Accuracy

    NASA Technical Reports Server (NTRS)

    Carter, Delano R.; Todirita, Monica; Kronenwetter, Jeffrey; Chu, Donald

    2016-01-01

    The GOES-R magnetometer subsystem accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma. Error comes both from outside the magnetometers, e.g. spacecraft fields and misalignments, as well as inside, e.g. zero offset and scale factor errors. Because zero offset and scale factor drift over time, it will be necessary to perform annual calibration maneuvers. To predict performance before launch, we have used Monte Carlo simulations and covariance analysis. Both behave as expected, and their accuracy predictions agree within 30%. With the proposed calibration regimen, both suggest that the GOES-R magnetometer subsystem will meet its accuracy requirements.

  15. Investigating Absolute Value: A Real World Application

    ERIC Educational Resources Information Center

    Kidd, Margaret; Pagni, David

    2009-01-01

    Making connections between various representations is important in mathematics. In this article, the authors discuss the numeric, algebraic, and graphical representations of sums of absolute values of linear functions. The initial explanations are accessible to all students who have experience graphing and who understand that absolute value simply…

  16. Preschoolers' Success at Coding Absolute Size Values.

    ERIC Educational Resources Information Center

    Russell, James

    1980-01-01

    Forty-five 2-year-old and forty-five 3-year-old children coded relative and absolute sizes using 1.5-inch, 6-inch, and 18-inch cardboard squares. Results indicate that absolute coding is possible for children of this age. (Author/RH)

  17. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  18. Monolithically integrated absolute frequency comb laser system

    DOEpatents

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  19. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  20. Mini-implants and miniplates generate sub-absolute and absolute anchorage

    PubMed Central

    Consolaro, Alberto

    2014-01-01

    The functional demand imposed on bone promotes changes in the spatial properties of osteocytes as well as in their extensions uniformly distributed throughout the mineralized surface. Once spatial deformation is established, osteocytes create the need for structural adaptations that result in bone formation and resorption that happen to meet the functional demands. The endosteum and the periosteum are the effectors responsible for stimulating adaptive osteocytes in the inner and outer surfaces.Changes in shape, volume and position of the jaws as a result of skeletal correction of the maxilla and mandible require anchorage to allow bone remodeling to redefine morphology, esthetics and function as a result of spatial deformation conducted by orthodontic appliances. Examining the degree of changes in shape, volume and structural relationship of areas where mini-implants and miniplates are placed allows us to classify mini-implants as devices of subabsolute anchorage and miniplates as devices of absolute anchorage. PMID:25162561

  1. An ultrasonic system for measurement of absolute myocardial thickness using a single transducer.

    PubMed

    Pitsillides, K F; Longhurst, J C

    1995-03-01

    We have developed an ultrasonic instrument that can measure absolute regional myocardial wall motion throughout the cardiac cycle using a single epicardial piezoelectric transducer. The methods in place currently that utilize ultrasound to measure myocardial wall thickness are the transit-time sonomicrometer (TTS) and, more recently, the Doppler echo displacement method. Both methods have inherent disadvantages. To address the need for an instrument that can measure absolute dimensions of myocardial wall at any depth, an ultrasonic single-crystal sonomicrometer (SCS) system was developed. This system can identify and track the boundary of the endocardial muscle-blood interface. With this instrument, it is possible to obtain, from a single epicardial transducer, measurement of myocardial wall motion that is calibrated in absolute dimensional units. The operating principles of the proposed myocardial dimension measurement system are as follows. A short duration ultrasonic burst having a frequency of 10 MHz is transmitted from the piezoelectric transducer. Reflected echoes are sampled at two distinct time intervals to generate reference and interface sample volumes. During steady state, the two sample volumes are adjusted so that the reference volume remains entirely within the myocardium, whereas half of the interface sampled volume is located within the myocardium. After amplification and filtering, the true root mean square values of both signals are compared and an error signal is generated. A closed-loop circuit uses the integrated error signal to continuously adjust the position of the two sample volumes. We have compared our system in vitro against a known signal and in vivo against the two-crystal TTS system during control, suppression (ischemia), and enhancement (isoproterenol) of myocardial function. Results were obtained in vitro for accuracy (> 99%), signal linearity (r = 0.99), and frequency response to heart rates > 450 beats/min, and in vivo data were

  2. Absolute Temperature Monitoring Using RF Radiometry in the MRI Scanner.

    PubMed

    El-Sharkawy, Abdel-Monem M; Sotiriadis, Paul P; Bottomley, Paul A; Atalar, Ergin

    2006-11-01

    Temperature detection using microwave radiometry has proven value for noninvasively measuring the absolute temperature of tissues inside the body. However, current clinical radiometers operate in the gigahertz range, which limits their depth of penetration. We have designed and built a noninvasive radiometer which operates at radio frequencies (64 MHz) with ∼100-kHz bandwidth, using an external RF loop coil as a thermal detector. The core of the radiometer is an accurate impedance measurement and automatic matching circuit of 0.05 Ω accuracy to compensate for any load variations. The radiometer permits temperature measurements with accuracy of ±0.1°K, over a tested physiological range of 28° C-40° C in saline phantoms whose electric properties match those of tissue. Because 1.5 T magnetic resonance imaging (MRI) scanners also operate at 64 MHz, we demonstrate the feasibility of integrating our radiometer with an MRI scanner to monitor RF power deposition and temperature dosimetry, obtaining coarse, spatially resolved, absolute thermal maps in the physiological range. We conclude that RF radiometry offers promise as a direct, noninvasive method of monitoring tissue heating during MRI studies and thereby providing an independent means of verifying patient-safe operation. Other potential applications include titration of hyper- and hypo-therapies. PMID:18026562

  3. Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

    SciTech Connect

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron L. C.; Kristensen, Anders

    2014-08-18

    A class of photonic crystal resonant reflectors known as guided mode resonant filters are optical structures that are widely used in the field of refractive index sensing, particularly in biosensing. For the purposes of understanding and design, their behavior has traditionally been modeled numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken into account. Furthermore, it is demonstrated that the model is valid beyond the limit of low grating modulation, for periodically discontinuous waveguide layers, high refractive index contrasts, and highly dispersive media.

  4. Absolute astrometry with Pan-STARRS

    NASA Astrophysics Data System (ADS)

    Makarov, Valeri; Berghea, Ciprian; Dorland, Bryan; Hennessy, Greg; Zacharias, Norbert; Magnier, Eugene A.; Monet, David; Gaume, Ralph

    2015-08-01

    A small collaboration of USNO and IfA astronomers is working on an improved astrometric solution for the data collected by the Pan-STARRS project. The 3PI survey performed by the PS1 telescope is well suited for a global astrometric solution. The current approach used in the data reduction pipeline is strictly differential. The 2MASS positions were used as reference for field of view (FoV) and detector calibration procedures. The absence of proper motions in 2MASS results in significant sky-correlated errors up to 30 - 50 mas. Our approach is to solve a huge system of linear equations for a carefully selected set of ~1 million grid objects including the astrometric unknowns (positions, proper motions and parallaxes) and FoV calibration parameters. The grid catalog includes ~5000 extragalactic radio sources with VLBI-detected positions accurate to 1 mas or better, which are used as hard constraints to the astrometric unknowns in the global least-squares adjustment. If successful, this will be the first realization of a large optical astrometry catalog directly anchored to the ICRF. Numerical simulations indicated a 10 mas accuracy level for Pan-STARRS astrometry, but experimental solutions on real data have not yet reached this level.

  5. Relative Accuracy Evaluation

    PubMed Central

    Zhang, Yan; Wang, Hongzhi; Yang, Zhongsheng; Li, Jianzhong

    2014-01-01

    The quality of data plays an important role in business analysis and decision making, and data accuracy is an important aspect in data quality. Thus one necessary task for data quality management is to evaluate the accuracy of the data. And in order to solve the problem that the accuracy of the whole data set is low while a useful part may be high, it is also necessary to evaluate the accuracy of the query results, called relative accuracy. However, as far as we know, neither measure nor effective methods for the accuracy evaluation methods are proposed. Motivated by this, for relative accuracy evaluation, we propose a systematic method. We design a relative accuracy evaluation framework for relational databases based on a new metric to measure the accuracy using statistics. We apply the methods to evaluate the precision and recall of basic queries, which show the result's relative accuracy. We also propose the method to handle data update and to improve accuracy evaluation using functional dependencies. Extensive experimental results show the effectiveness and efficiency of our proposed framework and algorithms. PMID:25133752

  6. Relative vertical positioning using ground-level transponders with the ERS-1 altimeter

    NASA Astrophysics Data System (ADS)

    Powell, R. J.

    1985-06-01

    A technique for using the ERS-1 altimeter to measure the relative vertical position of land-based transponders and the ocean geoid on 2000 km long segments of the satellite ground track is proposed. The absolute position accuracy is similar to that of the laser tracking stations, relative accuracy may be of the order of a few centimeters, and measurements of changes in transponder elevation during the 3 yr satellite life may be at the sub-centimeter level. The opportunity for such measurements is provided by exploiting together very accurate range measurements made to ground-based transponders and the demonstrated constancy of form of satellite short-arc orbits repeated over an identical ground track. Altimetric vertical position measurements of this accuracy make possible techniques for altimeter calibration, sea-state bias measurements, orbit measurement and seismic/geodetic study.

  7. Demonstrating the Error Budget for the Climate Absolute Radiance and Refractivity Observatory Through Solar Irradiance Measurements

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2016-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as a method to determine the accuracy of climate change. A CLARREO objective is to improve the accuracy of SI-traceable, absolute calibration at infrared and reflected solar wavelengths to reach on-orbit accuracies required to allow climate change observations to survive data gaps and observe climate change at the limit of natural variability. Such an effort will also demonstrate National Institute of Standards and Technology (NIST) approaches for use in future spaceborne instruments. The current work describes the results of laboratory and field measurements with the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. SOLARIS allows testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. Results of laboratory calibration measurements are provided to demonstrate key assumptions about instrument behavior that are needed to achieve CLARREO's climate measurement requirements. Absolute radiometric response is determined using laser-based calibration sources and applied to direct solar views for comparison with accepted solar irradiance models to demonstrate accuracy values giving confidence in the error budget for the CLARREO reflectance retrieval.

  8. Absolute Identification Is Relative: A Reply to Brown, Marley, and Lacouture (2007)

    ERIC Educational Resources Information Center

    Stewart, Neil

    2007-01-01

    N. Stewart, G. D. A. Brown, and N. Chater presented a relative judgment model (RJM) of absolute identification, in which the current stimulus is judged relative to the preceding stimulus. S. Brown, A. A. J. Marley, and Y. Lacouture found that the RJM does not predict their finding of increased accuracy after large stimulus jumps, except at the…

  9. Demonstrating the error budget for the Climate Absolute Radiance and Refractivity Observatory through solar irradiance measurements

    NASA Astrophysics Data System (ADS)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2015-09-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as a method to determine the accuracy of climate change. A CLARREO objective is to improve the accuracy of SI-traceable, absolute calibration at infrared and reflected solar wavelengths to reach on-orbit accuracies required to allow climate change observations to survive data gaps and observe climate change at the limit of natural variability. Such an effort will also demonstrate National Institute of Standards and Technology (NIST) approaches for use in future spaceborne instruments. The current work describes the results of laboratory and field measurements with the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. SOLARIS allows testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a testbed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. Results of laboratory calibration measurements are provided to demonstrate key assumptions about instrument behavior that are needed to achieve CLARREO's climate measurement requirements. Absolute radiometric response is determined using laser-based calibration sources and applied to direct solar views for comparison with accepted solar irradiance models to demonstrate accuracy values giving confidence in the error budget for the CLARREO reflectance retrieval.

  10. The Effect of Using Relative and Absolute Criteria to Decide Students' Passing or Failing a Course

    ERIC Educational Resources Information Center

    Sayin, Ayfer

    2016-01-01

    In the formation education that is carried out within the scope of undergraduate and non-thesis graduate programs within the same university, different criteria are used to evaluate students' success. In this study, classification accuracy of letter grades that are generated to evaluate students' success using relative and absolute criteria and…

  11. IMPROVEMENT OF SMVGEAR II ON VECTOR AND SCALAR MACHINES THROUGH ABSOLUTE ERROR TOLERANCE CONTROL (R823186)

    EPA Science Inventory

    The computer speed of SMVGEAR II was improved markedly on scalar and vector machines with relatively little loss in accuracy. The improvement was due to a method of frequently recalculating the absolute error tolerance instead of keeping it constant for a given set of chemistry. ...

  12. Electrical Noise and the Measurement of Absolute Temperature, Boltzmann's Constant and Avogadro's Number.

    ERIC Educational Resources Information Center

    Ericson, T. J.

    1988-01-01

    Describes an apparatus capable of measuring absolute temperatures of a tungsten filament bulb up to normal running temperature and measuring Botzmann's constant to an accuracy of a few percent. Shows that electrical noise techniques are convenient to demonstrate how the concept of temperature is related to the micro- and macroscopic world. (CW)

  13. Absolute flatness testing of skip-flat interferometry by matrix analysis in polar coordinates.

    PubMed

    Han, Zhi-Gang; Yin, Lu; Chen, Lei; Zhu, Ri-Hong

    2016-03-20

    A new method utilizing matrix analysis in polar coordinates has been presented for absolute testing of skip-flat interferometry. The retrieval of the absolute profile mainly includes three steps: (1) transform the wavefront maps of the two cavity measurements into data in polar coordinates; (2) retrieve the profile of the reflective flat in polar coordinates by matrix analysis; and (3) transform the profile of the reflective flat back into data in Cartesian coordinates and retrieve the profile of the sample. Simulation of synthetic surface data has been provided, showing the capability of the approach to achieve an accuracy of the order of 0.01 nm RMS. The absolute profile can be retrieved by a set of closed mathematical formulas without polynomial fitting of wavefront maps or the iterative evaluation of an error function, making the new method more efficient for absolute testing.

  14. Absolute magnitudes of trans-neptunian objects

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.

    2015-10-01

    Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise absolute magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate absolute magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and modelled, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure absolute magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 absolute magnitudes.

  15. A New Gimmick for Assigning Absolute Configuration.

    ERIC Educational Resources Information Center

    Ayorinde, F. O.

    1983-01-01

    A five-step procedure is provided to help students in making the assignment absolute configuration less bothersome. Examples for both single (2-butanol) and multi-chiral carbon (3-chloro-2-butanol) molecules are included. (JN)

  16. The Simplicity Argument and Absolute Morality

    ERIC Educational Resources Information Center

    Mijuskovic, Ben

    1975-01-01

    In this paper the author has maintained that there is a similarity of thought to be found in the writings of Cudworth, Emerson, and Husserl in his investigation of an absolute system of morality. (Author/RK)

  17. On-Orbit Absolute Radiance Standard for Future IR Remote Sensing Instruments

    NASA Astrophysics Data System (ADS)

    Best, F. A.; Adler, D. P.; Pettersen, C.; Revercomb, H. E.; Gero, P. J.; Taylor, J. K.; Knuteson, R. O.; Perepezko, J. H.

    2010-12-01

    Future NASA infrared remote sensing missions, including the climate benchmark CLARREO mission will require better absolute measurement accuracy than now available, and will most certainly rely on the emerging capability to fly SI traceable standards that provide irrefutable absolute measurement accuracy. As an example, instrumentation designed to measure spectrally resolved infrared radiances with an absolute brightness temperature error of better than 0.1 K will require high-emissivity (>0.999) calibration blackbodies with emissivity uncertainty of better than 0.06%, and absolute temperature uncertainties of better than 0.045K (3 sigma). Key elements of an On-Orbit Absolute Radiance Standard (OARS) meeting these stringent requirements have been demonstrated in the laboratory at the University of Wisconsin and are undergoing Technology Readiness Level (TRL) advancement under the NASA Instrument Incubator Program (IIP). We present the new technologies that underlie the OARS and the results of laboratory testing that demonstrate the required accuracy is being met. The underlying technologies include on-orbit absolute temperature calibration using the transient melt signatures of small quantities (<1g) of reference materials (gallium, water, and mercury) imbedded in the blackbody cavity; and on-orbit cavity spectral emissivity measurement using a heated halo. For these emissivity measurements, a carefully baffled heated cylinder is placed in front of a blackbody in the infrared spectrometer system, and the combined radiance of the blackbody and Heated Halo reflection is observed. Knowledge of key temperatures and the viewing geometry allow the blackbody cavity spectral emissivity to be calculated. This work will culminate with an integrated subsystem that can provide on-orbit end-to-end radiometric accuracy validation for infrared remote sensing instruments.

  18. Reticence, Accuracy and Efficacy

    NASA Astrophysics Data System (ADS)

    Oreskes, N.; Lewandowsky, S.

    2015-12-01

    James Hansen has cautioned the scientific community against "reticence," by which he means a reluctance to speak in public about the threat of climate change. This may contribute to social inaction, with the result that society fails to respond appropriately to threats that are well understood scientifically. Against this, others have warned against the dangers of "crying wolf," suggesting that reticence protects scientific credibility. We argue that both these positions are missing an important point: that reticence is not only a matter of style but also of substance. In previous work, Bysse et al. (2013) showed that scientific projections of key indicators of climate change have been skewed towards the low end of actual events, suggesting a bias in scientific work. More recently, we have shown that scientific efforts to be responsive to contrarian challenges have led scientists to adopt the terminology of a "pause" or "hiatus" in climate warming, despite the lack of evidence to support such a conclusion (Lewandowsky et al., 2015a. 2015b). In the former case, scientific conservatism has led to under-estimation of climate related changes. In the latter case, the use of misleading terminology has perpetuated scientific misunderstanding and hindered effective communication. Scientific communication should embody two equally important goals: 1) accuracy in communicating scientific information and 2) efficacy in expressing what that information means. Scientists should strive to be neither conservative nor adventurous but to be accurate, and to communicate that accurate information effectively.

  19. Assessing and ensuring GOES-R magnetometer accuracy

    NASA Astrophysics Data System (ADS)

    Carter, Delano; Todirita, Monica; Kronenwetter, Jeffrey; Dahya, Melissa; Chu, Donald

    2016-05-01

    The GOES-R magnetometer subsystem accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma error per axis. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma error per axis. Error comes both from outside the magnetometers, e.g. spacecraft fields and misalignments, as well as inside, e.g. zero offset and scale factor errors. Because zero offset and scale factor drift over time, it will be necessary to perform annual calibration maneuvers. To predict performance before launch, we have used Monte Carlo simulations and covariance analysis. With the proposed calibration regimen, both suggest that the magnetometer subsystem will meet its accuracy requirements.

  20. Orion Absolute Navigation System Progress and Challenge

    NASA Technical Reports Server (NTRS)

    Holt, Greg N.; D'Souza, Christopher

    2012-01-01

    The absolute navigation design of NASA's Orion vehicle is described. It has undergone several iterations and modifications since its inception, and continues as a work-in-progress. This paper seeks to benchmark the current state of the design and some of the rationale and analysis behind it. There are specific challenges to address when preparing a timely and effective design for the Exploration Flight Test (EFT-1), while still looking ahead and providing software extensibility for future exploration missions. The primary onboard measurements in a Near-Earth or Mid-Earth environment consist of GPS pseudo-range and delta-range, but for future explorations missions the use of star-tracker and optical navigation sources need to be considered. Discussions are presented for state size and composition, processing techniques, and consider states. A presentation is given for the processing technique using the computationally stable and robust UDU formulation with an Agee-Turner Rank-One update. This allows for computational savings when dealing with many parameters which are modeled as slowly varying Gauss-Markov processes. Preliminary analysis shows up to a 50% reduction in computation versus a more traditional formulation. Several state elements are discussed and evaluated, including position, velocity, attitude, clock bias/drift, and GPS measurement biases in addition to bias, scale factor, misalignment, and non-orthogonalities of the accelerometers and gyroscopes. Another consideration is the initialization of the EKF in various scenarios. Scenarios such as single-event upset, ground command, and cold start are discussed as are strategies for whole and partial state updates as well as covariance considerations. Strategies are given for dealing with latent measurements and high-rate propagation using multi-rate architecture. The details of the rate groups and the data ow between the elements is discussed and evaluated.

  1. Accuracy of the Cloud Integrating Nephelometer

    NASA Technical Reports Server (NTRS)

    Gerber, Hermann E.

    2004-01-01

    Potential error sources for measurements with the Cloud Integrating Nephelometer (CIN) are discussed and analyzed, including systematic errors of the measurement approach, flow and particle-trajectory deviations at flight velocity, ice-crystal breakup on probe surfaces, and errors in calibration and developing scaling constants. It is concluded that errors are minimal, and that the accuracy of the CIN should be close to the systematic behavior of the CIN derived in Gerber et al (2000). Absolute calibration of the CIN with a transmissometer operating co-located in a mountain-top cloud shows that the earlier scaling constant for the optical extinction coefficient obtained by other means is within 5% of the absolute calibration value, and that the CIN measurements on the Citation aircraft flights during the CRYSTAL-FACE study are accurate.

  2. Matching accuracy in hemiparetic cerebral palsy during unimanual and bimanual movements with (mirror) visual feedback.

    PubMed

    Smorenburg, Ana R P; Ledebt, Annick; Deconinck, Frederik J A; Savelsbergh, Geert J P

    2012-01-01

    In the present study participants with Spastic Hemiparetic Cerebral Palsy (SHCP) were asked to match the position of a target either with the impaired arm only (unimanual condition) or with both arms at the same time (bimanual condition). The target was placed at 4 different locations scaled to the individual maximum reaching distance. To test the effect of mirror visual feedback of the less-impaired arm on the matching accuracy, an opaque screen or a mirror was placed in between the arms which masked vision of the impaired arm. Absolute endpoint error was smaller in the bimanual condition compared to the unimanual condition, but there was no effect of mirror visual feedback. Inspection of the individual data, however, showed that 13 out of 23 participants did experience a positive effect of mirror visual feedback. A positive correlation between the baseline error (screen) and the improvement in accuracy with mirror visual feedback seems to suggest that individuals with lower proprioceptive accuracy in the baseline condition may benefit more from mirror visual feedback. Together these findings indicate that bimanual therapy and therapy with mirror visual feedback might be valuable approaches for rehabilitation for a subset of the individuals with SHCP. PMID:22771984

  3. Drawing accuracy measured using polygons

    NASA Astrophysics Data System (ADS)

    Carson, Linda; Millard, Matthew; Quehl, Nadine; Danckert, James

    2013-03-01

    The study of drawing, for its own sake and as a probe into human visual perception, generally depends on ratings by human critics and self-reported expertise of the drawers. To complement those approaches, we have developed a geometric approach to analyzing drawing accuracy, one whose measures are objective, continuous and performance-based. Drawing geometry is represented by polygons formed by landmark points found in the drawing. Drawing accuracy is assessed by comparing the geometric properties of polygons in the drawn image to the equivalent polygon in a ground truth photo. There are four distinct properties of a polygon: its size, its position, its orientation and the proportionality of its shape. We can decompose error into four components and investigate how each contributes to drawing performance. We applied a polygon-based accuracy analysis to a pilot data set of representational drawings and found that an expert drawer outperformed a novice on every dimension of polygon error. The results of the pilot data analysis correspond well with the apparent quality of the drawings, suggesting that the landmark and polygon analysis is a method worthy of further study. Applying this geometric analysis to a within-subjects comparison of accuracy in the positive and negative space suggests there is a trade-off on dimensions of error. The performance-based analysis of geometric deformations will allow the study of drawing accuracy at different levels of organization, in a systematic and quantitative manner. We briefly describe the method and its potential applications to research in drawing education and visual perception.

  4. Geolocation Accuracy Evaluations of OrbView-3, EROS-A, and SPOT-5 Imagery

    NASA Technical Reports Server (NTRS)

    Bresnahan, Paul

    2007-01-01

    This viewgraph presentation evaluates absolute geolocation accuracy of OrbView-3, EROS-A, and SPOT-5 by comparing test imagery-derived ground coordinates to Ground Control Points using SOCET set photogrammetric software.

  5. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    PubMed

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed.

  6. Absolute radiometric calibration of Als intensity data: effects on accuracy and target classification.

    PubMed

    Kaasalainen, Sanna; Pyysalo, Ulla; Krooks, Anssi; Vain, Ants; Kukko, Antero; Hyyppä, Juha; Kaasalainen, Mikko

    2011-01-01

    Radiometric calibration of airborne laser scanning (ALS) intensity data aims at retrieving a value related to the target scattering properties, which is independent on the instrument or flight parameters. The aim of a calibration procedure is also to be able to compare results from different flights and instruments, but practical applications are sparsely available, and the performance of calibration methods for this purpose needs to be further assessed. We have studied the radiometric calibration with data from three separate flights and two different instruments using external calibration targets. We find that the intensity data from different flights and instruments can be compared to each other only after a radiometric calibration process using separate calibration targets carefully selected for each flight. The calibration is also necessary for target classification purposes, such as separating vegetation from sand using intensity data from different flights. The classification results are meaningful only for calibrated intensity data.

  7. Improvement in absolute calibration accuracy of Landsat-5 TM with Landsat-7 ETM+ data

    NASA Astrophysics Data System (ADS)

    Chander, Gyanesh; Markham, Brian L.; Micijevic, Esad; Teillet, Philippe M.; Helder, Dennis L.

    2005-08-01

    The ability to detect and quantify changes in the Earth's environment depends on satellites sensors that can provide calibrated, consistent measurements of Earth's surface features through time. A critical step in this process is to put image data from subsequent generations of sensors onto a common radiometric scale. To evaluate Landsat-5 (L5) Thematic Mapper's (TM) utility in this role, image pairs from the L5 TM and Landsat-7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensors were compared. This approach involves comparison of surface observations based on image statistics from large common areas observed eight days apart by the two sensors. The results indicate a significant improvement in the consistency of L5 TM data with respect to L7 ETM+ data, achieved using a revised Look-Up-Table (LUT) procedure as opposed to the historical Internal Calibrator (IC) procedure previously used in the L5 TM product generation system. The average percent difference in reflectance estimates obtained from the L5 TM agree with those from the L7 ETM+ in the Visible and Near Infrared (VNIR) bands to within four percent and in the Short Wave Infrared (SWIR) bands to within six percent.

  8. Absolute radiometric calibration of Als intensity data: effects on accuracy and target classification.

    PubMed

    Kaasalainen, Sanna; Pyysalo, Ulla; Krooks, Anssi; Vain, Ants; Kukko, Antero; Hyyppä, Juha; Kaasalainen, Mikko

    2011-01-01

    Radiometric calibration of airborne laser scanning (ALS) intensity data aims at retrieving a value related to the target scattering properties, which is independent on the instrument or flight parameters. The aim of a calibration procedure is also to be able to compare results from different flights and instruments, but practical applications are sparsely available, and the performance of calibration methods for this purpose needs to be further assessed. We have studied the radiometric calibration with data from three separate flights and two different instruments using external calibration targets. We find that the intensity data from different flights and instruments can be compared to each other only after a radiometric calibration process using separate calibration targets carefully selected for each flight. The calibration is also necessary for target classification purposes, such as separating vegetation from sand using intensity data from different flights. The classification results are meaningful only for calibrated intensity data. PMID:22346660

  9. Improvement in absolute calibration accuracy of Landsat-5 TM with Landsat-7 ETM+ data

    USGS Publications Warehouse

    Chander, G.; Markham, B.L.; Micijevic, E.; Teillet, P.M.; Helder, D.L.; ,

    2005-01-01

    The ability to detect and quantify changes in the Earth's environment depends on satellites sensors that can provide calibrated, consistent measurements of Earth's surface features through time. A critical step in this process is to put image data from subsequent generations of sensors onto a common radiometric scale. To evaluate Landsat-5 (L5) Thematic Mapper's (TM) utility in this role, image pairs from the L5 TM and Landsat-7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensors were compared. This approach involves comparison of surface observations based on image statistics from large common areas observed eight days apart by the two sensors. The results indicate a significant improvement in the consistency of L5 TM data with respect to L7 ETM+ data, achieved using a revised Look-Up-Table (LUT) procedure as opposed to the historical Internal Calibrator (IC) procedure previously used in the L5 TM product generation system. The average percent difference in reflectance estimates obtained from the L5 TM agree with those from the L7 ETM+ in the Visible and Near Infrared (VNIR) bands to within four percent and in the Short Wave Infrared (SWIR) bands to within six percent.

  10. Universal Cosmic Absolute and Modern Science

    NASA Astrophysics Data System (ADS)

    Kostro, Ludwik

    The official Sciences, especially all natural sciences, respect in their researches the principle of methodic naturalism i.e. they consider all phenomena as entirely natural and therefore in their scientific explanations they do never adduce or cite supernatural entities and forces. The purpose of this paper is to show that Modern Science has its own self-existent, self-acting, and self-sufficient Natural All-in Being or Omni-Being i.e. the entire Nature as a Whole that justifies the scientific methodic naturalism. Since this Natural All-in Being is one and only It should be considered as the own scientifically justified Natural Absolute of Science and should be called, in my opinion, the Universal Cosmic Absolute of Modern Science. It will be also shown that the Universal Cosmic Absolute is ontologically enormously stratified and is in its ultimate i.e. in its most fundamental stratum trans-reistic and trans-personal. It means that in its basic stratum. It is neither a Thing or a Person although It contains in Itself all things and persons with all other sentient and conscious individuals as well, On the turn of the 20th century the Science has begun to look for a theory of everything, for a final theory, for a master theory. In my opinion the natural Universal Cosmic Absolute will constitute in such a theory the radical all penetrating Ultimate Basic Reality and will substitute step by step the traditional supernatural personal Absolute.

  11. Comparative Accuracy Evaluation of Fine-Scale Global and Local Digital Surface Models: The Tshwane Case Study I

    NASA Astrophysics Data System (ADS)

    Breytenbach, A.

    2016-10-01

    Conducted in the City of Tshwane, South Africa, this study set about to test the accuracy of DSMs derived from different remotely sensed data locally. VHR digital mapping camera stereo-pairs, tri-stereo imagery collected by a Pléiades satellite and data detected from the Tandem-X InSAR satellite configuration were fundamental in the construction of seamless DSM products at different postings, namely 2 m, 4 m and 12 m. The three DSMs were sampled against independent control points originating from validated airborne LiDAR data. The reference surfaces were derived from the same dense point cloud at grid resolutions corresponding to those of the samples. The absolute and relative positional accuracies were computed using well-known DEM error metrics and accuracy statistics. Overall vertical accuracies were also assessed and compared across seven slope classes and nine primary land cover classes. Although all three DSMs displayed significantly more vertical errors where solid waterbodies, dense natural and/or alien woody vegetation and, in a lesser degree, urban residential areas with significant canopy cover were encountered, all three surpassed their expected positional accuracies overall.

  12. Quantum theory allows for absolute maximal contextuality

    NASA Astrophysics Data System (ADS)

    Amaral, Barbara; Cunha, Marcelo Terra; Cabello, Adán

    2015-12-01

    Contextuality is a fundamental feature of quantum theory and a necessary resource for quantum computation and communication. It is therefore important to investigate how large contextuality can be in quantum theory. Linear contextuality witnesses can be expressed as a sum S of n probabilities, and the independence number α and the Tsirelson-like number ϑ of the corresponding exclusivity graph are, respectively, the maximum of S for noncontextual theories and for the theory under consideration. A theory allows for absolute maximal contextuality if it has scenarios in which ϑ /α approaches n . Here we show that quantum theory allows for absolute maximal contextuality despite what is suggested by the examination of the quantum violations of Bell and noncontextuality inequalities considered in the past. Our proof is not constructive and does not single out explicit scenarios. Nevertheless, we identify scenarios in which quantum theory allows for almost-absolute-maximal contextuality.

  13. Absolute calibration in vivo measurement systems

    SciTech Connect

    Kruchten, D.A.; Hickman, D.P.

    1991-02-01

    Lawrence Livermore National Laboratory (LLNL) is currently investigating a new method for obtaining absolute calibration factors for radiation measurement systems used to measure internally deposited radionuclides in vivo. Absolute calibration of in vivo measurement systems will eliminate the need to generate a series of human surrogate structures (i.e., phantoms) for calibrating in vivo measurement systems. The absolute calibration of in vivo measurement systems utilizes magnetic resonance imaging (MRI) to define physiological structure, size, and composition. The MRI image provides a digitized representation of the physiological structure, which allows for any mathematical distribution of radionuclides within the body. Using Monte Carlo transport codes, the emission spectrum from the body is predicted. The in vivo measurement equipment is calibrated using the Monte Carlo code and adjusting for the intrinsic properties of the detection system. The calibration factors are verified using measurements of existing phantoms and previously obtained measurements of human volunteers. 8 refs.

  14. Quantitative standards for absolute linguistic universals.

    PubMed

    Piantadosi, Steven T; Gibson, Edward

    2014-01-01

    Absolute linguistic universals are often justified by cross-linguistic analysis: If all observed languages exhibit a property, the property is taken to be a likely universal, perhaps specified in the cognitive or linguistic systems of language learners and users. In many cases, these patterns are then taken to motivate linguistic theory. Here, we show that cross-linguistic analysis will very rarely be able to statistically justify absolute, inviolable patterns in language. We formalize two statistical methods--frequentist and Bayesian--and show that in both it is possible to find strict linguistic universals, but that the numbers of independent languages necessary to do so is generally unachievable. This suggests that methods other than typological statistics are necessary to establish absolute properties of human language, and thus that many of the purported universals in linguistics have not received sufficient empirical justification.

  15. Molecular iodine absolute frequencies. Final report

    SciTech Connect

    Sansonetti, C.J.

    1990-06-25

    Fifty specified lines of {sup 127}I{sub 2} were studied by Doppler-free frequency modulation spectroscopy. For each line the classification of the molecular transition was determined, hyperfine components were identified, and one well-resolved component was selected for precise determination of its absolute frequency. In 3 cases, a nearby alternate line was selected for measurement because no well-resolved component was found for the specified line. Absolute frequency determinations were made with an estimated uncertainty of 1.1 MHz by locking a dye laser to the selected hyperfine component and measuring its wave number with a high-precision Fabry-Perot wavemeter. For each line results of the absolute measurement, the line classification, and a Doppler-free spectrum are given.

  16. Absolute pitch in Costa Rica: Distribution of pitch identification ability and implications for its genetic basis.

    PubMed

    Chavarria-Soley, Gabriela

    2016-08-01

    Absolute pitch is the unusual ability to recognize a pitch without an external reference. The current view is that both environmental and genetic factors are involved in the acquisition of the trait. In the present study, 127 adult musicians were subjected to a musical tone identification test. Subjects were university music students and volunteers who responded to a newspaper article. The test consisted of the identification of 40 piano and 40 pure tones. Subjects were classified in three categories according to their pitch naming ability: absolute pitch (AP), high accuracy of tone identification (HA), and non-absolute pitch (non-AP). Both the percentage of correct responses and the mean absolute deviation showed a statistically significant variation between categories. A very clear pattern of higher accuracy for white than for black key notes was observed for the HA and the non-AP groups. Meanwhile, the AP group had an almost perfect pitch naming accuracy for both kinds of tones. Each category presented a very different pattern of deviation around the correct response. The age at the beginning of musical training did not differ between categories. The distribution of pitch identification ability in this study suggests a complex inheritance of the trait. PMID:27586721

  17. A multilaboratory comparison of calibration accuracy and the performance of external references in analytical ultracentrifugation.

    PubMed

    Zhao, Huaying; Ghirlando, Rodolfo; Alfonso, Carlos; Arisaka, Fumio; Attali, Ilan; Bain, David L; Bakhtina, Marina M; Becker, Donald F; Bedwell, Gregory J; Bekdemir, Ahmet; Besong, Tabot M D; Birck, Catherine; Brautigam, Chad A; Brennerman, William; Byron, Olwyn; Bzowska, Agnieszka; Chaires, Jonathan B; Chaton, Catherine T; Cölfen, Helmut; Connaghan, Keith D; Crowley, Kimberly A; Curth, Ute; Daviter, Tina; Dean, William L; Díez, Ana I; Ebel, Christine; Eckert, Debra M; Eisele, Leslie E; Eisenstein, Edward; England, Patrick; Escalante, Carlos; Fagan, Jeffrey A; Fairman, Robert; Finn, Ron M; Fischle, Wolfgang; de la Torre, José García; Gor, Jayesh; Gustafsson, Henning; Hall, Damien; Harding, Stephen E; Cifre, José G Hernández; Herr, Andrew B; Howell, Elizabeth E; Isaac, Richard S; Jao, Shu-Chuan; Jose, Davis; Kim, Soon-Jong; Kokona, Bashkim; Kornblatt, Jack A; Kosek, Dalibor; Krayukhina, Elena; Krzizike, Daniel; Kusznir, Eric A; Kwon, Hyewon; Larson, Adam; Laue, Thomas M; Le Roy, Aline; Leech, Andrew P; Lilie, Hauke; Luger, Karolin; Luque-Ortega, Juan R; Ma, Jia; May, Carrie A; Maynard, Ernest L; Modrak-Wojcik, Anna; Mok, Yee-Foong; Mücke, Norbert; Nagel-Steger, Luitgard; Narlikar, Geeta J; Noda, Masanori; Nourse, Amanda; Obsil, Tomas; Park, Chad K; Park, Jin-Ku; Pawelek, Peter D; Perdue, Erby E; Perkins, Stephen J; Perugini, Matthew A; Peterson, Craig L; Peverelli, Martin G; Piszczek, Grzegorz; Prag, Gali; Prevelige, Peter E; Raynal, Bertrand D E; Rezabkova, Lenka; Richter, Klaus; Ringel, Alison E; Rosenberg, Rose; Rowe, Arthur J; Rufer, Arne C; Scott, David J; Seravalli, Javier G; Solovyova, Alexandra S; Song, Renjie; Staunton, David; Stoddard, Caitlin; Stott, Katherine; Strauss, Holger M; Streicher, Werner W; Sumida, John P; Swygert, Sarah G; Szczepanowski, Roman H; Tessmer, Ingrid; Toth, Ronald T; Tripathy, Ashutosh; Uchiyama, Susumu; Uebel, Stephan F W; Unzai, Satoru; Gruber, Anna Vitlin; von Hippel, Peter H; Wandrey, Christine; Wang, Szu-Huan; Weitzel, Steven E; Wielgus-Kutrowska, Beata; Wolberger, Cynthia; Wolff, Martin; Wright, Edward; Wu, Yu-Sung; Wubben, Jacinta M; Schuck, Peter

    2015-01-01

    Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies.

  18. A multilaboratory comparison of calibration accuracy and the performance of external references in analytical ultracentrifugation.

    PubMed

    Zhao, Huaying; Ghirlando, Rodolfo; Alfonso, Carlos; Arisaka, Fumio; Attali, Ilan; Bain, David L; Bakhtina, Marina M; Becker, Donald F; Bedwell, Gregory J; Bekdemir, Ahmet; Besong, Tabot M D; Birck, Catherine; Brautigam, Chad A; Brennerman, William; Byron, Olwyn; Bzowska, Agnieszka; Chaires, Jonathan B; Chaton, Catherine T; Cölfen, Helmut; Connaghan, Keith D; Crowley, Kimberly A; Curth, Ute; Daviter, Tina; Dean, William L; Díez, Ana I; Ebel, Christine; Eckert, Debra M; Eisele, Leslie E; Eisenstein, Edward; England, Patrick; Escalante, Carlos; Fagan, Jeffrey A; Fairman, Robert; Finn, Ron M; Fischle, Wolfgang; de la Torre, José García; Gor, Jayesh; Gustafsson, Henning; Hall, Damien; Harding, Stephen E; Cifre, José G Hernández; Herr, Andrew B; Howell, Elizabeth E; Isaac, Richard S; Jao, Shu-Chuan; Jose, Davis; Kim, Soon-Jong; Kokona, Bashkim; Kornblatt, Jack A; Kosek, Dalibor; Krayukhina, Elena; Krzizike, Daniel; Kusznir, Eric A; Kwon, Hyewon; Larson, Adam; Laue, Thomas M; Le Roy, Aline; Leech, Andrew P; Lilie, Hauke; Luger, Karolin; Luque-Ortega, Juan R; Ma, Jia; May, Carrie A; Maynard, Ernest L; Modrak-Wojcik, Anna; Mok, Yee-Foong; Mücke, Norbert; Nagel-Steger, Luitgard; Narlikar, Geeta J; Noda, Masanori; Nourse, Amanda; Obsil, Tomas; Park, Chad K; Park, Jin-Ku; Pawelek, Peter D; Perdue, Erby E; Perkins, Stephen J; Perugini, Matthew A; Peterson, Craig L; Peverelli, Martin G; Piszczek, Grzegorz; Prag, Gali; Prevelige, Peter E; Raynal, Bertrand D E; Rezabkova, Lenka; Richter, Klaus; Ringel, Alison E; Rosenberg, Rose; Rowe, Arthur J; Rufer, Arne C; Scott, David J; Seravalli, Javier G; Solovyova, Alexandra S; Song, Renjie; Staunton, David; Stoddard, Caitlin; Stott, Katherine; Strauss, Holger M; Streicher, Werner W; Sumida, John P; Swygert, Sarah G; Szczepanowski, Roman H; Tessmer, Ingrid; Toth, Ronald T; Tripathy, Ashutosh; Uchiyama, Susumu; Uebel, Stephan F W; Unzai, Satoru; Gruber, Anna Vitlin; von Hippel, Peter H; Wandrey, Christine; Wang, Szu-Huan; Weitzel, Steven E; Wielgus-Kutrowska, Beata; Wolberger, Cynthia; Wolff, Martin; Wright, Edward; Wu, Yu-Sung; Wubben, Jacinta M; Schuck, Peter

    2015-01-01

    Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies. PMID:25997164

  19. A Multilaboratory Comparison of Calibration Accuracy and the Performance of External References in Analytical Ultracentrifugation

    PubMed Central

    Zhao, Huaying; Ghirlando, Rodolfo; Alfonso, Carlos; Arisaka, Fumio; Attali, Ilan; Bain, David L.; Bakhtina, Marina M.; Becker, Donald F.; Bedwell, Gregory J.; Bekdemir, Ahmet; Besong, Tabot M. D.; Birck, Catherine; Brautigam, Chad A.; Brennerman, William; Byron, Olwyn; Bzowska, Agnieszka; Chaires, Jonathan B.; Chaton, Catherine T.; Cölfen, Helmut; Connaghan, Keith D.; Crowley, Kimberly A.; Curth, Ute; Daviter, Tina; Dean, William L.; Díez, Ana I.; Ebel, Christine; Eckert, Debra M.; Eisele, Leslie E.; Eisenstein, Edward; England, Patrick; Escalante, Carlos; Fagan, Jeffrey A.; Fairman, Robert; Finn, Ron M.; Fischle, Wolfgang; de la Torre, José García; Gor, Jayesh; Gustafsson, Henning; Hall, Damien; Harding, Stephen E.; Cifre, José G. Hernández; Herr, Andrew B.; Howell, Elizabeth E.; Isaac, Richard S.; Jao, Shu-Chuan; Jose, Davis; Kim, Soon-Jong; Kokona, Bashkim; Kornblatt, Jack A.; Kosek, Dalibor; Krayukhina, Elena; Krzizike, Daniel; Kusznir, Eric A.; Kwon, Hyewon; Larson, Adam; Laue, Thomas M.; Le Roy, Aline; Leech, Andrew P.; Lilie, Hauke; Luger, Karolin; Luque-Ortega, Juan R.; Ma, Jia; May, Carrie A.; Maynard, Ernest L.; Modrak-Wojcik, Anna; Mok, Yee-Foong; Mücke, Norbert; Nagel-Steger, Luitgard; Narlikar, Geeta J.; Noda, Masanori; Nourse, Amanda; Obsil, Tomas; Park, Chad K.; Park, Jin-Ku; Pawelek, Peter D.; Perdue, Erby E.; Perkins, Stephen J.; Perugini, Matthew A.; Peterson, Craig L.; Peverelli, Martin G.; Piszczek, Grzegorz; Prag, Gali; Prevelige, Peter E.; Raynal, Bertrand D. E.; Rezabkova, Lenka; Richter, Klaus; Ringel, Alison E.; Rosenberg, Rose; Rowe, Arthur J.; Rufer, Arne C.; Scott, David J.; Seravalli, Javier G.; Solovyova, Alexandra S.; Song, Renjie; Staunton, David; Stoddard, Caitlin; Stott, Katherine; Strauss, Holger M.; Streicher, Werner W.; Sumida, John P.; Swygert, Sarah G.; Szczepanowski, Roman H.; Tessmer, Ingrid; Toth, Ronald T.; Tripathy, Ashutosh; Uchiyama, Susumu; Uebel, Stephan F. W.; Unzai, Satoru; Gruber, Anna Vitlin; von Hippel, Peter H.; Wandrey, Christine; Wang, Szu-Huan; Weitzel, Steven E.; Wielgus-Kutrowska, Beata; Wolberger, Cynthia; Wolff, Martin; Wright, Edward; Wu, Yu-Sung; Wubben, Jacinta M.; Schuck, Peter

    2015-01-01

    Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies. PMID:25997164

  20. Son preference in Indian families: absolute versus relative wealth effects.

    PubMed

    Gaudin, Sylvestre

    2011-02-01

    The desire for male children is prevalent in India, where son preference has been shown to affect fertility behavior and intrahousehold allocation of resources. Economic theory predicts less gender discrimination in wealthier households, but demographers and sociologists have argued that wealth can exacerbate bias in the Indian context. I argue that these apparently conflicting theories can be reconciled and simultaneously tested if one considers that they are based on two different notions of wealth: one related to resource constraints (absolute wealth), and the other to notions of local status (relative wealth). Using cross-sectional data from the 1998-1999 and 2005-2006 National Family and Health Surveys, I construct measures of absolute and relative wealth by using principal components analysis. A series of statistical models of son preference is estimated by using multilevel methods. Results consistently show that higher absolute wealth is strongly associated with lower son preference, and the effect is 20%-40% stronger when the household's community-specific wealth score is included in the regression. Coefficients on relative wealth are positive and significant although lower in magnitude. Results are robust to using different samples, alternative groupings of households in local areas, different estimation methods, and alternative dependent variables.

  1. Absolute Stability And Hyperstability In Hilbert Space

    NASA Technical Reports Server (NTRS)

    Wen, John Ting-Yung

    1989-01-01

    Theorems on stabilities of feedback control systems proved. Paper presents recent developments regarding theorems of absolute stability and hyperstability of feedforward-and-feedback control system. Theorems applied in analysis of nonlinear, adaptive, and robust control. Extended to provide sufficient conditions for stability in system including nonlinear feedback subsystem and linear time-invariant (LTI) feedforward subsystem, state space of which is Hilbert space, and input and output spaces having finite numbers of dimensions. (In case of absolute stability, feedback subsystem memoryless and possibly time varying. For hyperstability, feedback system dynamical system.)

  2. Absolute properties of the triple star HP Aurigae

    SciTech Connect

    Lacy, Claud H. Sandberg; Burks, Charles L.; Torres, Guillermo; Wolf, Marek E-mail: clburks@email.uark.edu E-mail: wolf@cesnet.cz

    2014-01-01

    New photometric, spectroscopic, and eclipse timing observations of the eclipsing binary star HP Aur allow for very accurate orbital determinations, even in the presence of a third body and transient starspot activity. The eclipsing binary masses are determined to an accuracy of ±0.4% and the radii to ±0.6%. The masses are 0.9543 ± 0.0041 and 0.8094 ± 0.0036 solar masses, and the radii are 1.0278 ± 0.0042 and 0.7758 ± 0.0034 solar radii, respectively. The orbital period in the outer orbit is accurately determined for the first time: 4.332 ± 0.011 yr. A comparison with current theories of stellar evolution shows that the components' absolute properties can be well-matched by the current models at an age of about 7 billion years.

  3. Landsat-5 TM reflective-band absolute radiometric calibration

    USGS Publications Warehouse

    Chander, G.; Helder, D.L.; Markham, B.L.; Dewald, J.D.; Kaita, E.; Thome, K.J.; Micijevic, E.; Ruggles, T.A.

    2004-01-01

    The Landsat-5 Thematic Mapper (TM) sensor provides the longest running continuous dataset of moderate spatial resolution remote sensing imagery, dating back to its launch in March 1984. Historically, the radiometric calibration procedure for this imagery used the instrument's response to the Internal Calibrator (IC) on a scene-by-scene basis to determine the gain and offset of each detector. Due to observed degradations in the IC, a new procedure was implemented for U.S.-processed data in May 2003. This new calibration procedure is based on a lifetime radiometric calibration model for the instrument's reflective bands (1-5 and 7) and is derived, in part, from the IC response without the related degradation effects and is tied to the cross calibration with the Landsat-7 Enhanced Thematic Mapper Plus. Reflective-band absolute radiometric accuracy of the instrument tends to be on the order of 7% to 10%, based on a variety of calibration methods.

  4. Assignment of absolute stereostructures through quantum mechanics electronic and vibrational circular dichroism calculations.

    PubMed

    Dai, Peng; Jiang, Nan; Tan, Ren-Xiang

    2016-01-01

    Elucidation of absolute configuration of chiral molecules including structurally complex natural products remains a challenging problem in organic chemistry. A reliable method for assigning the absolute stereostructure is to combine the experimental circular dichroism (CD) techniques such as electronic and vibrational CD (ECD and VCD), with quantum mechanics (QM) ECD and VCD calculations. The traditional QM methods as well as their continuing developments make them more applicable with accuracy. Taking some chiral natural products with diverse conformations as examples, this review describes the basic concepts and new developments of QM approaches for ECD and VCD calculations in solution and solid states.

  5. Metrological activity determination of 133Ba by sum-peak absolute method

    NASA Astrophysics Data System (ADS)

    da Silva, R. L.; de Almeida, M. C. M.; Delgado, J. U.; Poledna, R.; Santos, A.; de Veras, E. V.; Rangel, J.; Trindade, O. L.

    2016-07-01

    The National Laboratory for Metrology of Ionizing Radiation provides gamma sources of radionuclide and standardized in activity with reduced uncertainties. Relative methods require standards to determine the sample activity while the absolute methods, as sum-peak, not. The activity is obtained directly with good accuracy and low uncertainties. 133Ba is used in research laboratories and on calibration of detectors for analysis in different work areas. Classical absolute methods don't calibrate 133Ba due to its complex decay scheme. The sum-peak method using gamma spectrometry with germanium detector standardizes 133Ba samples. Uncertainties lower than 1% to activity results were obtained.

  6. Enabling Dark Energy and Beyond Science with Precise Absolute Photometry

    NASA Astrophysics Data System (ADS)

    Deustua, Susana E.; Hines, D. C.; Bohlin, R.; Gordon, K. D.

    2014-01-01

    We have obtain WFC3/IR observations of 15 carefully selected stars with the immediate objective of establishing their Absolute Physical Flux (ABF), and an ultimate goal of achieving the sub-1% absolute photometric accuracies required by Dark Energy science with JWST and other facilities. Even with the best data available, the current determination of ABFs is plagued by the reliance on the Vega photometric system, which is known to be problematic primarily due to the fact that Vega is a pole-on rapid rotator with an infrared excess from its circumstellar disk! which makes it difficult to model. Vega is also far too bright for large aperture telescopes. In an effort to remedy these difficulties, teams from the National Institute of Standards (NIST), the University of New Mexico, Johns Hopkins University and STScI have begun to develop a catalog of stars that have spectral energy distributions that are tied directly to NIST (diode) standards with very precisely determined physical characteristics. A key element in this pursuit has been the efforts at STScI to measure the spectra of many of these objects with STIS. We discuss our program to extend this effort into the near-IR which is crucial to reliably extend the SEDs to longer wavelengths, including the mid IR.

  7. Low cost varying synthetic wavelength technique for absolute distance measurement

    NASA Astrophysics Data System (ADS)

    Le Floch, S.; Salvadé, Y.

    2010-04-01

    A new low-cost superheterodyne configuration, without acousto-optic modulator, is applied to the two-wavelength interferometry for absolute distance measurement. The principle relies on a synchronized frequency sweep of two optical signals, but with different frequency excursions. The frequency difference between the two optical waves is highly accurate. This is realized by injecting a frequency modulated laser signal in an intensity modulator that is biased at halfwave voltage and driven by a digitally swept radio-frequency signal between 13 and 15 GHz. This latter is a continuous up and down ramp. The two synchronized optical signals emerging from the modulator produce in a Michelson interferometer a distance dependent superheterodyne signal, with a variable synthetic wavelength of about 10 mm. The superheterodyne frequency depends linearly on distance and on the radio-frequency excursion. The integration time for a distance measurement point corresponds to the duration of single sweep (i.e. one millisecond in our case). Absolute distance measurements from 1 to 15 meters yield an accuracy of +/-50 μm, showing the validity of the technique.

  8. Mitigation of Atmospheric Delay in SAR Absolute Ranging Using Global Numerical Weather Prediction Data: Corner Reflector Experiments at 3 Different Test Sites

    NASA Astrophysics Data System (ADS)

    Cong, Xiaoying; Balss, Ulrich; Eineder, Michael

    2015-04-01

    The atmospheric delay due to vertical stratification, the so-called stratified atmospheric delay, has a great impact on both interferometric and absolute range measurements. In our current researches [1][2][3], centimeter-range accuracy has been proven based on Corner Reflector (CR) based measurements by applying atmospheric delay correction using the Zenith Path Delay (ZPD) corrections derived from nearby Global Positioning System (GPS) stations. For a global usage, an effective method has been introduced to estimate the stratified delay based on global 4-dimensional Numerical Weather Prediction (NWP) products: the direct integration method [4][5]. Two products, ERA-Interim and operational data, provided by European Centre for Medium-Range Weather Forecast (ECMWF) are used to integrate the stratified delay. In order to access the integration accuracy, a validation approach is investigated based on ZPD derived from six permanent GPS stations located in different meteorological conditions. Range accuracy at centimeter level is demonstrated using both ECMWF products. Further experiments have been carried out in order to determine the best interpolation method by analyzing the temporal and spatial correlation of atmospheric delay using both ECMWF and GPS ZPD. Finally, the integrated atmospheric delays in slant direction (Slant Path Delay, SPD) have been applied instead of the GPS ZPD for CR experiments at three different test sites with more than 200 TerraSAR-X High Resolution SpotLight (HRSL) images. The delay accuracy is around 1-3 cm depending on the location of test site due to the local water vapor variation and the acquisition time/date. [1] Eineder M., Minet C., Steigenberger P., et al. Imaging geodesy - Toward centimeter-level ranging accuracy with TerraSAR-X. Geoscience and Remote Sensing, IEEE Transactions on, 2011, 49(2): 661-671. [2] Balss U., Gisinger C., Cong X. Y., et al. Precise Measurements on the Absolute Localization Accuracy of TerraSAR-X on the

  9. Development of a GPS-aided motion measurement, pointing, and stabilization system for a Synthetic Aperture Radar. [Global Positioning System (GPS)

    SciTech Connect

    Fellerhoff, J.R.; Kohler, S.M.

    1991-01-01

    An advanced Synthetic Aperture Radar Motion Compensation System has been developed by Sandia National Laboratories (SNL). The system includes a miniaturized high accuracy ring laser gyro inertial measurement unit, a three axis gimbal pointing and stabilization assembly, a differential Global Positioning System (GPS) navigation aiding system, and a pilot guidance system. The system provides several improvements over previous SNL motion compensation systems and is capable of antenna stabilization to less than 0.01 degrees RMS and absolute position measurement to less than 5.0 meters RMS. These accuracies have been demonstrated in recent flight testing aboard a DHC-6-300 Twin Otter'' aircraft.

  10. GEOSPATIAL DATA ACCURACY ASSESSMENT

    EPA Science Inventory

    The development of robust accuracy assessment methods for the validation of spatial data represent's a difficult scientific challenge for the geospatial science community. The importance and timeliness of this issue is related directly to the dramatic escalation in the developmen...

  11. Classification accuracy improvement

    NASA Technical Reports Server (NTRS)

    Kistler, R.; Kriegler, F. J.

    1977-01-01

    Improvements made in processing system designed for MIDAS (prototype multivariate interactive digital analysis system) effects higher accuracy in classification of pixels, resulting in significantly-reduced processing time. Improved system realizes cost reduction factor of 20 or more.

  12. Measuring Postglacial Rebound with GPS and Absolute Gravity

    NASA Technical Reports Server (NTRS)

    Larson, Kristine M.; vanDam, Tonie

    2000-01-01

    We compare vertical rates of deformation derived from continuous Global Positioning System (GPS) observations and episodic measurements of absolute gravity. We concentrate on four sites in a region of North America experiencing postglacial rebound. The rates of uplift from gravity and GPS agree within one standard deviation for all sites. The GPS vertical deformation rates are significantly more precise than the gravity rates, primarily because of the denser temporal spacing provided by continuous GPS tracking. We conclude that continuous GPS observations are more cost efficient and provide more precise estimates of vertical deformation rates than campaign style gravity observations where systematic errors are difficult to quantify.

  13. Inertial Measures of Motion for Clinical Biomechanics: Comparative Assessment of Accuracy under Controlled Conditions – Changes in Accuracy over Time

    PubMed Central

    Lebel, Karina; Boissy, Patrick; Hamel, Mathieu; Duval, Christian

    2015-01-01

    Background Interest in 3D inertial motion tracking devices (AHRS) has been growing rapidly among the biomechanical community. Although the convenience of such tracking devices seems to open a whole new world of possibilities for evaluation in clinical biomechanics, its limitations haven’t been extensively documented. The objectives of this study are: 1) to assess the change in absolute and relative accuracy of multiple units of 3 commercially available AHRS over time; and 2) to identify different sources of errors affecting AHRS accuracy and to document how they may affect the measurements over time. Methods This study used an instrumented Gimbal table on which AHRS modules were carefully attached and put through a series of velocity-controlled sustained motions including 2 minutes motion trials (2MT) and 12 minutes multiple dynamic phases motion trials (12MDP). Absolute accuracy was assessed by comparison of the AHRS orientation measurements to those of an optical gold standard. Relative accuracy was evaluated using the variation in relative orientation between modules during the trials. Findings Both absolute and relative accuracy decreased over time during 2MT. 12MDP trials showed a significant decrease in accuracy over multiple phases, but accuracy could be enhanced significantly by resetting the reference point and/or compensating for initial Inertial frame estimation reference for each phase. Interpretation The variation in AHRS accuracy observed between the different systems and with time can be attributed in part to the dynamic estimation error, but also and foremost, to the ability of AHRS units to locate the same Inertial frame. Conclusions Mean accuracies obtained under the Gimbal table sustained conditions of motion suggest that AHRS are promising tools for clinical mobility assessment under constrained conditions of use. However, improvement in magnetic compensation and alignment between AHRS modules are desirable in order for AHRS to reach their

  14. Overlay accuracy fundamentals

    NASA Astrophysics Data System (ADS)

    Kandel, Daniel; Levinski, Vladimir; Sapiens, Noam; Cohen, Guy; Amit, Eran; Klein, Dana; Vakshtein, Irina

    2012-03-01

    Currently, the performance of overlay metrology is evaluated mainly based on random error contributions such as precision and TIS variability. With the expected shrinkage of the overlay metrology budget to < 0.5nm, it becomes crucial to include also systematic error contributions which affect the accuracy of the metrology. Here we discuss fundamental aspects of overlay accuracy and a methodology to improve accuracy significantly. We identify overlay mark imperfections and their interaction with the metrology technology, as the main source of overlay inaccuracy. The most important type of mark imperfection is mark asymmetry. Overlay mark asymmetry leads to a geometrical ambiguity in the definition of overlay, which can be ~1nm or less. It is shown theoretically and in simulations that the metrology may enhance the effect of overlay mark asymmetry significantly and lead to metrology inaccuracy ~10nm, much larger than the geometrical ambiguity. The analysis is carried out for two different overlay metrology technologies: Imaging overlay and DBO (1st order diffraction based overlay). It is demonstrated that the sensitivity of DBO to overlay mark asymmetry is larger than the sensitivity of imaging overlay. Finally, we show that a recently developed measurement quality metric serves as a valuable tool for improving overlay metrology accuracy. Simulation results demonstrate that the accuracy of imaging overlay can be improved significantly by recipe setup optimized using the quality metric. We conclude that imaging overlay metrology, complemented by appropriate use of measurement quality metric, results in optimal overlay accuracy.

  15. Absolute Points for Multiple Assignment Problems

    ERIC Educational Resources Information Center

    Adlakha, V.; Kowalski, K.

    2006-01-01

    An algorithm is presented to solve multiple assignment problems in which a cost is incurred only when an assignment is made at a given cell. The proposed method recursively searches for single/group absolute points to identify cells that must be loaded in any optimal solution. Unlike other methods, the first solution is the optimal solution. The…

  16. Absolute partial photoionization cross sections of ozone.

    SciTech Connect

    Berkowitz, J.; Chemistry

    2008-04-01

    Despite the current concerns about ozone, absolute partial photoionization cross sections for this molecule in the vacuum ultraviolet (valence) region have been unavailable. By eclectic re-evaluation of old/new data and plausible assumptions, such cross sections have been assembled to fill this void.

  17. Teaching Absolute Value Inequalities to Mature Students

    ERIC Educational Resources Information Center

    Sierpinska, Anna; Bobos, Georgeana; Pruncut, Andreea

    2011-01-01

    This paper gives an account of a teaching experiment on absolute value inequalities, whose aim was to identify characteristics of an approach that would realize the potential of the topic to develop theoretical thinking in students enrolled in prerequisite mathematics courses at a large, urban North American university. The potential is…

  18. Solving Absolute Value Equations Algebraically and Geometrically

    ERIC Educational Resources Information Center

    Shiyuan, Wei

    2005-01-01

    The way in which students can improve their comprehension by understanding the geometrical meaning of algebraic equations or solving algebraic equation geometrically is described. Students can experiment with the conditions of the absolute value equation presented, for an interesting way to form an overall understanding of the concept.

  19. Increasing Capacity: Practice Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Dodds, Pennie; Donkin, Christopher; Brown, Scott D.; Heathcote, Andrew

    2011-01-01

    In most of the long history of the study of absolute identification--since Miller's (1956) seminal article--a severe limit on performance has been observed, and this limit has resisted improvement even by extensive practice. In a startling result, Rouder, Morey, Cowan, and Pfaltz (2004) found substantially improved performance with practice in the…

  20. Absolute Radiometric Calibration Of The Thematic Mapper

    NASA Astrophysics Data System (ADS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.; Moran, M. S.; Palmer, J. M.; Yuan, B.

    1986-11-01

    The results are presented of five in-flight absolute radiometric calibrations, made in the period July 1984 to November 1985, at White Sands, New Mexico, of the solar reflective bands of the Landsat-5 Thematic Mapper (TM) . The 23 bandcalibrations made on the five dates show a ± 2.8% RMS variation from the mean as a percentage of the mean.

  1. On Relative and Absolute Conviction in Mathematics

    ERIC Educational Resources Information Center

    Weber, Keith; Mejia-Ramos, Juan Pablo

    2015-01-01

    Conviction is a central construct in mathematics education research on justification and proof. In this paper, we claim that it is important to distinguish between absolute conviction and relative conviction. We argue that researchers in mathematics education frequently have not done so and this has lead to researchers making unwarranted claims…

  2. Accuracy analysis of the space shuttle solid rocket motor profile measuring device

    NASA Technical Reports Server (NTRS)

    Estler, W. Tyler

    1989-01-01

    The Profile Measuring Device (PMD) was developed at the George C. Marshall Space Flight Center following the loss of the Space Shuttle Challenger. It is a rotating gauge used to measure the absolute diameters of mating features of redesigned Solid Rocket Motor field joints. Diameter tolerance of these features are typically + or - 0.005 inches and it is required that the PMD absolute measurement uncertainty be within this tolerance. In this analysis, the absolute accuracy of these measurements were found to be + or - 0.00375 inches, worst case, with a potential accuracy of + or - 0.0021 inches achievable by improved temperature control.

  3. In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; /more authors..

    2012-09-20

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron-plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between {approx}6 and {approx}13 GeV with an estimated uncertainty of {approx}2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.

  4. In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Barbielini, G; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B,; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Gehrels, N.; Hays, E.; McEnery, J. E.; Thompson, D. J.; Troja, E. J.

    2012-01-01

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron- plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between approx. 6 and approx. 13 GeV with an estimated uncertainty of approx. 2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.

  5. 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, respectively. Why? We use different but…

  6. Metrical Patterns of Words and Production Accuracy.

    ERIC Educational Resources Information Center

    Schwartz, Richard G.; Goffman, Lisa

    1995-01-01

    This study examined the influence of metrical patterns (syllable stress and serial position) of words on the production accuracy of 20 children (ages 22 months to 28 months). Among results were that one-fourth of the initial unstressed syllables were omitted and that consonant omissions, though few, tended to occur in the initial position.…

  7. Predict Gram-Positive and Gram-Negative Subcellular Localization via Incorporating Evolutionary Information and Physicochemical Features Into Chou's General PseAAC.

    PubMed

    Sharma, Ronesh; Dehzangi, Abdollah; Lyons, James; Paliwal, Kuldip; Tsunoda, Tatsuhiko; Sharma, Alok

    2015-12-01

    In this study, we used structural and evolutionary based features to represent the sequences of gram-positive and gram-negative subcellular localizations. To do this, we proposed a normalization method to construct a normalize Position Specific Scoring Matrix (PSSM) using the information from original PSSM. To investigate the effectiveness of the proposed method we compute feature vectors from normalize PSSM and by applying support vector machine (SVM) and naïve Bayes classifier, respectively, we compared achieved results with the previously reported results. We also computed features from original PSSM and normalized PSSM and compared their results. The archived results show enhancement in gram-positive and gram-negative subcellular localizations. Evaluating localization for each feature, our results indicate that employing SVM and concatenating features (amino acid composition feature, Dubchak feature (physicochemical-based features), normalized PSSM based auto-covariance feature and normalized PSSM based bigram feature) have higher accuracy while employing naïve Bayes classifier with normalized PSSM based auto-covariance feature proves to have high sensitivity for both benchmarks. Our reported results in terms of overall locative accuracy is 84.8% and overall absolute accuracy is 85.16% for gram-positive dataset; and, for gram-negative dataset, overall locative accuracy is 85.4% and overall absolute accuracy is 86.3%.

  8. Deformation modes in the finite element absolute nodal coordinate formulation

    NASA Astrophysics Data System (ADS)

    Sugiyama, Hiroyuki; Gerstmayr, Johannes; Shabana, Ahmed A.

    2006-12-01

    The objective of this study is to provide interpretation of the deformation modes in the finite element absolute nodal coordinate formulation using several strain definitions. In this finite element formulation, the nodal coordinates consist of absolute position coordinates and gradients that can be used to define a unique rotation and deformation fields within the element as well as at the nodal points. The results obtained in this study clearly show cross-section deformation modes eliminated when the number of the finite element nodal coordinates is systematically and consistently reduced. Using the procedure discussed in this paper one can obtain a reduced order dynamic model, eliminate position vector gradients that introduce high frequencies to the solution of some problems, achieve the continuity of the remaining gradients at the nodal points, and obtain a formulation that automatically satisfies the principle of work and energy. Furthermore, the resulting dynamic model, unlike large rotation finite element formulations, leads to a unique rotation field, and as a consequence, the obtained formulation does not suffer from the problem of coordinate redundancy that characterizes existing large deformation finite element formulations. In order to accurately define strain components that can have easy physical interpretation, a material coordinate system is introduced to define the material element rotation and deformation. Using the material coordinate system, the Timoshenko-Reissner and Euler -Bernoulli beam models can be systematically obtained as special cases of the absolute nodal coordinate formulation beam models. While a constraint approach is used in this study to eliminate the cross-section deformation modes, it is important to point out as mentioned in this paper that lower-order finite elements, some of which already presented in previous investigations, can be efficiently used in thin and stiff structure applications.

  9. Serial-position effects in motor short-term memory.

    PubMed

    Magill, R A; Dowel, M N

    1977-12-01

    This study examined the effect of the length of a series of movements on the recall of those movements. Subjects (n = 45) were randomly assigned to one of three experimental groups with each group recalling either three, six, or nine movements on a linear-slide apparatus. The subjects, while blindfolded, were presented with each movement by actively moving to a stop. Recall occurred 5 sec after the last movement to a stop on a trial. All subjects were given nine trials, each containing a different series of to-be-recalled movements. Results indicated that absolute error of recall of the three movements increased in a linear fashion. However, for six and nine movements, a bowing effect of the recall curve was noted following the fifth position. A primacy effect was more evident than was a recency effect. Accuracy of recall was a function of list length up to six movements, after which accuracy was not further impaired.

  10. The Absolute Vector Magnetometers on Board Swarm, Lessons Learned From Two Years in Space.

    NASA Astrophysics Data System (ADS)

    Hulot, G.; Leger, J. M.; Vigneron, P.; Brocco, L.; Olsen, N.; Jager, T.; Bertrand, F.; Fratter, I.; Sirol, O.; Lalanne, X.

    2015-12-01

    ESA's Swarm satellites carry 4He absolute magnetometers (ASM), designed by CEA-Léti and developed in partnership with CNES. These instruments are the first-ever space-born magnetometers to use a common sensor to simultaneously deliver 1Hz independent absolute scalar and vector readings of the magnetic field. They have provided the very high accuracy scalar field data nominally required by the mission (for both science and calibration purposes, since each satellite also carries a low noise high frequency fluxgate magnetometer designed by DTU), but also very useful experimental absolute vector data. In this presentation, we will report on the status of the instruments, as well as on the various tests and investigations carried out using these experimental data since launch in November 2013. In particular, we will illustrate the advantages of flying ASM instruments on space-born magnetic missions for nominal data quality checks, geomagnetic field modeling and science objectives.

  11. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    NASA Astrophysics Data System (ADS)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  12. Measurement of absolute optical thickness of mask glass by wavelength-tuning Fourier analysis.

    PubMed

    Kim, Yangjin; Hbino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru

    2015-07-01

    Optical thickness is a fundamental characteristic of an optical component. A measurement method combining discrete Fourier-transform (DFT) analysis and a phase-shifting technique gives an appropriate value for the absolute optical thickness of a transparent plate. However, there is a systematic error caused by the nonlinearity of the phase-shifting technique. In this research the absolute optical-thickness distribution of mask blank glass was measured using DFT and wavelength-tuning Fizeau interferometry without using sensitive phase-shifting techniques. The error occurring during the DFT analysis was compensated for by using the unwrapping correlation. The experimental results indicated that the absolute optical thickness of mask glass was measured with an accuracy of 5 nm.

  13. Dichotomy and perceptual distortions in absolute pitch ability.

    PubMed

    Athos, E Alexandra; Levinson, Barbara; Kistler, Amy; Zemansky, Jason; Bostrom, Alan; Freimer, Nelson; Gitschier, Jane

    2007-09-11

    Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a "perceptual magnet" centered at the note "A." In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the "sharp" direction. These findings speak both to the process of acquisition of AP and to its stability.

  14. Dichotomy and perceptual distortions in absolute pitch ability

    PubMed Central

    Athos, E. Alexandra; Levinson, Barbara; Kistler, Amy; Zemansky, Jason; Bostrom, Alan; Freimer, Nelson; Gitschier, Jane

    2007-01-01

    Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a “perceptual magnet” centered at the note “A.” In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the “sharp” direction. These findings speak both to the process of acquisition of AP and to its stability. PMID:17724340

  15. Prospects for the Moon as an SI-Traceable Absolute Spectroradiometric Standard for Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Cramer, C. E.; Stone, T. C.; Lykke, K.; Woodward, J. T.

    2015-12-01

    The Earth's Moon has many physical properties that make it suitable for use as a reference light source for radiometric calibration of remote sensing satellite instruments. Lunar calibration has been successfully applied to many imagers in orbit, including both MODIS instruments and NPP-VIIRS, using the USGS ROLO model to predict the reference exoatmospheric lunar irradiance. Sensor response trending was developed for SeaWIFS with a relative accuracy better than 0.1 % per year with lunar calibration techniques. However, the Moon rarely is used as an absolute reference for on-orbit calibration, primarily due to uncertainties in the ROLO model absolute scale of 5%-10%. But this limitation lies only with the models - the Moon itself is radiometrically stable, and development of a high-accuracy absolute lunar reference is inherently feasible. A program has been undertaken by NIST to collect absolute measurements of the lunar spectral irradiance with absolute accuracy <1 % (k=2), traceable to SI radiometric units. Initial Moon observations were acquired from the Whipple Observatory on Mt. Hopkins, Arizona, elevation 2367 meters, with continuous spectral coverage from 380 nm to 1040 nm at ~3 nm resolution. The lunar spectrometer acquired calibration measurements several times each observing night by pointing to a calibrated integrating sphere source. The lunar spectral irradiance at the top of the atmosphere was derived from a time series of ground-based measurements by a Langley analysis that incorporated measured atmospheric conditions and ROLO model predictions for the change in irradiance resulting from the changing Sun-Moon-Observer geometry throughout each night. Two nights were selected for further study. An extensive error analysis, which includes instrument calibration and atmospheric correction terms, shows a combined standard uncertainty under 1 % over most of the spectral range. Comparison of these two nights' spectral irradiance measurements with predictions

  16. An absolute measure for a key currency

    NASA Astrophysics Data System (ADS)

    Oya, Shunsuke; Aihara, Kazuyuki; Hirata, Yoshito

    It is generally considered that the US dollar and the euro are the key currencies in the world and in Europe, respectively. However, there is no absolute general measure for a key currency. Here, we investigate the 24-hour periodicity of foreign exchange markets using a recurrence plot, and define an absolute measure for a key currency based on the strength of the periodicity. Moreover, we analyze the time evolution of this measure. The results show that the credibility of the US dollar has not decreased significantly since the Lehman shock, when the Lehman Brothers bankrupted and influenced the economic markets, and has increased even relatively better than that of the euro and that of the Japanese yen.

  17. Probing absolute spin polarization at the nanoscale.

    PubMed

    Eltschka, Matthias; Jäck, Berthold; Assig, Maximilian; Kondrashov, Oleg V; Skvortsov, Mikhail A; Etzkorn, Markus; Ast, Christian R; Kern, Klaus

    2014-12-10

    Probing absolute values of spin polarization at the nanoscale offers insight into the fundamental mechanisms of spin-dependent transport. Employing the Zeeman splitting in superconducting tips (Meservey-Tedrow-Fulde effect), we introduce a novel spin-polarized scanning tunneling microscopy that combines the probing capability of the absolute values of spin polarization with precise control at the atomic scale. We utilize our novel approach to measure the locally resolved spin polarization of magnetic Co nanoislands on Cu(111). We find that the spin polarization is enhanced by 65% when increasing the width of the tunnel barrier by only 2.3 Å due to the different decay of the electron orbitals into vacuum. PMID:25423049

  18. Absolute radiometry and the solar constant

    NASA Technical Reports Server (NTRS)

    Willson, R. C.

    1974-01-01

    A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).

  19. From Hubble's NGSL to Absolute Fluxes

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Lindler, Don

    2012-01-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R-l000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.00 microns. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsll. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We are therefore developing an observing procedure that should yield fluxes with uncertainties less than 1 % and will take part in an HST proposal to observe up to 15 stars using this new procedure.

  20. Impact of Winko on absolute discharges.

    PubMed

    Balachandra, Krishna; Swaminath, Sam; Litman, Larry C

    2004-01-01

    In Canada, case laws have had a significant impact on the way mentally ill offenders are managed, both in the criminal justice system and in the forensic mental health system. The Supreme Court of Canada's decision with respect to Winko has set a major precedent in the application of the test of significant risk to the safety of the public in making dispositions by the Ontario Review Board and granting absolute discharges to the mentally ill offenders in the forensic health system. Our study examines the impact of the Supreme Court of Canada's decision before and after Winko. The results show that the numbers of absolute discharges have increased post-Winko, which was statistically significant, but there could be other factors influencing this increase.

  1. Asteroid absolute magnitudes and slope parameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1991-01-01

    A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.

  2. Absolute-magnitude distributions of supernovae

    SciTech Connect

    Richardson, Dean; Wright, John; Jenkins III, Robert L.; Maddox, Larry

    2014-05-01

    The absolute-magnitude distributions of seven supernova (SN) types are presented. The data used here were primarily taken from the Asiago Supernova Catalogue, but were supplemented with additional data. We accounted for both foreground and host-galaxy extinction. A bootstrap method is used to correct the samples for Malmquist bias. Separately, we generate volume-limited samples, restricted to events within 100 Mpc. We find that the superluminous events (M{sub B} < –21) make up only about 0.1% of all SNe in the bias-corrected sample. The subluminous events (M{sub B} > –15) make up about 3%. The normal Ia distribution was the brightest with a mean absolute blue magnitude of –19.25. The IIP distribution was the dimmest at –16.75.

  3. A quantitative method for evaluating numerical simulation accuracy of time-transient Lamb wave propagation with its applications to selecting appropriate element size and time step.

    PubMed

    Wan, Xiang; Xu, Guanghua; Zhang, Qing; Tse, Peter W; Tan, Haihui

    2016-01-01

    Lamb wave technique has been widely used in non-destructive evaluation (NDE) and structural health monitoring (SHM). However, due to the multi-mode characteristics and dispersive nature, Lamb wave propagation behavior is much more complex than that of bulk waves. Numerous numerical simulations on Lamb wave propagation have been conducted to study its physical principles. However, few quantitative studies on evaluating the accuracy of these numerical simulations were reported. In this paper, a method based on cross correlation analysis for quantitatively evaluating the simulation accuracy of time-transient Lamb waves propagation is proposed. Two kinds of error, affecting the position and shape accuracies are firstly identified. Consequently, two quantitative indices, i.e., the GVE (group velocity error) and MACCC (maximum absolute value of cross correlation coefficient) derived from cross correlation analysis between a simulated signal and a reference waveform, are proposed to assess the position and shape errors of the simulated signal. In this way, the simulation accuracy on the position and shape is quantitatively evaluated. In order to apply this proposed method to select appropriate element size and time step, a specialized 2D-FEM program combined with the proposed method is developed. Then, the proper element size considering different element types and time step considering different time integration schemes are selected. These results proved that the proposed method is feasible and effective, and can be used as an efficient tool for quantitatively evaluating and verifying the simulation accuracy of time-transient Lamb wave propagation. PMID:26315506

  4. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1985-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  5. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1982-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  6. Relative errors can cue absolute visuomotor mappings.

    PubMed

    van Dam, Loes C J; Ernst, Marc O

    2015-12-01

    When repeatedly switching between two visuomotor mappings, e.g. in a reaching or pointing task, adaptation tends to speed up over time. That is, when the error in the feedback corresponds to a mapping switch, fast adaptation occurs. Yet, what is learned, the relative error or the absolute mappings? When switching between mappings, errors with a size corresponding to the relative difference between the mappings will occur more often than other large errors. Thus, we could learn to correct more for errors with this familiar size (Error Learning). On the other hand, it has been shown that the human visuomotor system can store several absolute visuomotor mappings (Mapping Learning) and can use associated contextual cues to retrieve them. Thus, when contextual information is present, no error feedback is needed to switch between mappings. Using a rapid pointing task, we investigated how these two types of learning may each contribute when repeatedly switching between mappings in the absence of task-irrelevant contextual cues. After training, we examined how participants changed their behaviour when a single error probe indicated either the often-experienced error (Error Learning) or one of the previously experienced absolute mappings (Mapping Learning). Results were consistent with Mapping Learning despite the relative nature of the error information in the feedback. This shows that errors in the feedback can have a double role in visuomotor behaviour: they drive the general adaptation process by making corrections possible on subsequent movements, as well as serve as contextual cues that can signal a learned absolute mapping. PMID:26280315

  7. The absolute spectrophotometric catalog by Anita Cochran

    NASA Astrophysics Data System (ADS)

    Burnashev, V. I.; Burnasheva, B. A.; Ruban, E. V.; Hagen-Torn, E. I.

    2014-06-01

    The absolute spectrophotometric catalog by Anita Cochran is presented in a machine-readable form. The catalog systematizes observations acquired at the McDonald Observatory in 1977-1978. The data are compared with other sources, in particular, the calculated broadband stellar magnitudes are compared with photometric observations by other authors, to show that the observational data given in the catalog are reliable and suitable for a variety of applications. Observations of variable stars of different types make Cochran's catalog especially valuable.

  8. Absolute magnitudes and kinematics of barium stars.

    NASA Astrophysics Data System (ADS)

    Gomez, A. E.; Luri, X.; Grenier, S.; Prevot, L.; Mennessier, M. O.; Figueras, F.; Torra, J.

    1997-03-01

    The absolute magnitude of barium stars has been obtained from kinematical data using a new algorithm based on the maximum-likelihood principle. The method allows to separate a sample into groups characterized by different mean absolute magnitudes, kinematics and z-scale heights. It also takes into account, simultaneously, the censorship in the sample and the errors on the observables. The method has been applied to a sample of 318 barium stars. Four groups have been detected. Three of them show a kinematical behaviour corresponding to disk population stars. The fourth group contains stars with halo kinematics. The luminosities of the disk population groups spread a large range. The intrinsically brightest one (M_v_=-1.5mag, σ_M_=0.5mag) seems to be an inhomogeneous group containing barium binaries as well as AGB single stars. The most numerous group (about 150 stars) has a mean absolute magnitude corresponding to stars in the red giant branch (M_v_=0.9mag, σ_M_=0.8mag). The third group contains barium dwarfs, the obtained mean absolute magnitude is characteristic of stars on the main sequence or on the subgiant branch (M_v_=3.3mag, σ_M_=0.5mag). The obtained mean luminosities as well as the kinematical results are compatible with an evolutionary link between barium dwarfs and classical barium giants. The highly luminous group is not linked with these last two groups. More high-resolution spectroscopic data will be necessary in order to better discriminate between barium and non-barium stars.

  9. Prelaunch absolute radiometric calibration of the reflective bands on the LANDSAT-4 protoflight Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Ball, D. L.; Leung, K. C.; Walker, J. A.

    1984-01-01

    The results of the absolute radiometric calibration of the LANDSAT 4 thematic mapper, as determined during pre-launch tests with a 122 cm integrating sphere, are presented. Detailed results for the best calibration of the protoflight TM are given, as well as summaries of other tests performed on the sensor. The dynamic range of the TM is within a few per cent of that required in all bands, except bands 1 and 3. Three detectors failed to pass the minimum SNR specified for their respective bands: band 5, channel 3 (dead), band 2, and channels 2 and 4 (noisy or slow response). Estimates of the absolute calibration accuracy for the TM show that the detectors are typically calibrated to 5% absolute error for the reflective bands; 10% full-scale accuracy was specified. Ten tests performed to transfer the detector absolute calibration to the internal calibrator show a 5% range at full scale in the transfer calibration; however, in two cases band 5 showed a 10% and a 7% difference.

  10. Chemical composition of French mimosa absolute oil.

    PubMed

    Perriot, Rodolphe; Breme, Katharina; Meierhenrich, Uwe J; Carenini, Elise; Ferrando, Georges; Baldovini, Nicolas

    2010-02-10

    Since decades mimosa (Acacia dealbata) absolute oil has been used in the flavor and perfume industry. Today, it finds an application in over 80 perfumes, and its worldwide industrial production is estimated five tons per year. Here we report on the chemical composition of French mimosa absolute oil. Straight-chain analogues from C6 to C26 with different functional groups (hydrocarbons, esters, aldehydes, diethyl acetals, alcohols, and ketones) were identified in the volatile fraction. Most of them are long-chain molecules: (Z)-heptadec-8-ene, heptadecane, nonadecane, and palmitic acid are the most abundant, and constituents such as 2-phenethyl alcohol, methyl anisate, and ethyl palmitate are present in smaller amounts. The heavier constituents were mainly triterpenoids such as lupenone and lupeol, which were identified as two of the main components. (Z)-Heptadec-8-ene, lupenone, and lupeol were quantified by GC-MS in SIM mode using external standards and represents 6%, 20%, and 7.8% (w/w) of the absolute oil. Moreover, odorant compounds were extracted by SPME and analyzed by GC-sniffing leading to the perception of 57 odorant zones, of which 37 compounds were identified by their odorant description, mass spectrum, retention index, and injection of the reference compound. PMID:20070087

  11. Measurement of absolute gravity acceleration in Firenze

    NASA Astrophysics Data System (ADS)

    de Angelis, M.; Greco, F.; Pistorio, A.; Poli, N.; Prevedelli, M.; Saccorotti, G.; Sorrentino, F.; Tino, G. M.

    2011-01-01

    This paper reports the results from the accurate measurement of the acceleration of gravity g taken at two separate premises in the Polo Scientifico of the University of Firenze (Italy). In these laboratories, two separate experiments aiming at measuring the Newtonian constant and testing the Newtonian law at short distances are in progress. Both experiments require an independent knowledge on the local value of g. The only available datum, pertaining to the italian zero-order gravity network, was taken more than 20 years ago at a distance of more than 60 km from the study site. Gravity measurements were conducted using an FG5 absolute gravimeter, and accompanied by seismic recordings for evaluating the noise condition at the site. The absolute accelerations of gravity at the two laboratories are (980 492 160.6 ± 4.0) μGal and (980 492 048.3 ± 3.0) μGal for the European Laboratory for Non-Linear Spectroscopy (LENS) and Dipartimento di Fisica e Astronomia, respectively. Other than for the two referenced experiments, the data here presented will serve as a benchmark for any future study requiring an accurate knowledge of the absolute value of the acceleration of gravity in the study region.

  12. A Methodology for Absolute Isotope Composition Measurement

    NASA Astrophysics Data System (ADS)

    Shen, J. J.; Lee, D.; Liang, W.

    2007-12-01

    Double spike technique was a well defined method for isotope composition measurement by TIMS of samples which have natural mass fractionation effect, but it is still a problem to define the isotope composition for double spike itself. In this study, we modified the old double spike technique and found that we could use the modified technique to solve the ¡§true¡¨ isotope composition of double spike itself. According the true isotope composition of double spike, we can measure the absolute isotope composition if the sample has natural fractionation effect. A new vector analytical method has been developed in order to obtain the true isotopic composition of a 42Ca-48Ca double spike, and this is achieved by using two different sample-spike mixtures combined with the double spike and the natural Ca data. Because the natural sample, the two mixtures, and the spike should all lie on a single mixing line, we are able to constrain the true isotopic composition of our double spike using this new approach. This method not only can be used in Ca system but also in Ti, Cr, Fe, Ni, Zn, Mo, Ba and Pb systems. The absolute double spike isotopic ratio is important, which can save a lot of time to check different reference standards. Especially for Pb, radiogenic isotope system, the decay systems embodied in three of four naturally occurring isotopes induce difficult to obtain true isotopic ratios for absolute dating.

  13. Chemical composition of French mimosa absolute oil.

    PubMed

    Perriot, Rodolphe; Breme, Katharina; Meierhenrich, Uwe J; Carenini, Elise; Ferrando, Georges; Baldovini, Nicolas

    2010-02-10

    Since decades mimosa (Acacia dealbata) absolute oil has been used in the flavor and perfume industry. Today, it finds an application in over 80 perfumes, and its worldwide industrial production is estimated five tons per year. Here we report on the chemical composition of French mimosa absolute oil. Straight-chain analogues from C6 to C26 with different functional groups (hydrocarbons, esters, aldehydes, diethyl acetals, alcohols, and ketones) were identified in the volatile fraction. Most of them are long-chain molecules: (Z)-heptadec-8-ene, heptadecane, nonadecane, and palmitic acid are the most abundant, and constituents such as 2-phenethyl alcohol, methyl anisate, and ethyl palmitate are present in smaller amounts. The heavier constituents were mainly triterpenoids such as lupenone and lupeol, which were identified as two of the main components. (Z)-Heptadec-8-ene, lupenone, and lupeol were quantified by GC-MS in SIM mode using external standards and represents 6%, 20%, and 7.8% (w/w) of the absolute oil. Moreover, odorant compounds were extracted by SPME and analyzed by GC-sniffing leading to the perception of 57 odorant zones, of which 37 compounds were identified by their odorant description, mass spectrum, retention index, and injection of the reference compound.

  14. High precision absolute distance measurement with the fiber femtosecond optical frequency comb

    NASA Astrophysics Data System (ADS)

    Guo, Jiashuai; Wu, Tengfei; Liang, Zhiguo; Wang, Yu; Han, Jibo

    2016-01-01

    The absolute distance measurement was experimentally demonstrated by using the fiber femtosecond optical frequency comb in air. The technique is based on the measurement of cross correlation between reference and measurement optical pulses. This method can achieve accuracy better than the commercial laser interferometer. It is attained sub-micrometer resolution in large scale measurement by using the fiber femtosecond optical frequency comb. It will be benefit for future laser lidar and satellite formation flying mission.

  15. Simple iodine reference at 1064 nm for absolute laser frequency determination in space applications.

    PubMed

    Kokuyama, Wataru; Numata, Kenji; Camp, Jordan

    2010-11-10

    Using an iodine cell with fixed gas pressure, we built a simple frequency reference at 1064 nm with 10 MHz absolute accuracy and used it to demonstrate deterministic phase locking between two single-frequency lasers. The reference was designed to be as simple as possible, and it does not use a cooler or frequency modulator. This system should be useful, especially for space interferometric missions such as the Laser Interferometer Space Antenna.

  16. Absolute testing of flats in sub-stitching interferometer by rotation-shift method

    NASA Astrophysics Data System (ADS)

    Jia, Xin; Xu, Fuchao; Xie, Weimin; Li, Yun; Xing, Tingwen

    2015-09-01

    Most of the commercial available sub-aperture stitching interferometers measure the surface with a standard lens that produces a reference wavefront, and the precision of the interferometer is generally limited by the standard lens. The test accuracy can be achieved by removing the error of reference surface by the absolute testing method. When the testing accuracy (repeatability and reproducibility) is close to 1nm, in addition to the reference surface, other factors will also affect the measuring accuracy such as environment, zoom magnification, stitching precision, tooling and fixture, the characteristics of optical materials and so on. We establish a stitching system in the thousand level cleanroom. The stitching system is including the Zygo interferometer, the motion system with Bilz active isolation system at level VC-F. We review the traditional absolute flat testing methods and emphasize the method of rotation-shift functions. According to the rotation-shift method we get the profile of the reference lens and the testing lens. The problem of the rotation-shift method is the tilt error. In the motion system, we control the tilt error no more than 4 second to reduce the error. In order to obtain higher testing accuracy, we analyze the influence surface shape measurement accuracy by recording the environment error with the fluke testing equipment.

  17. Accuracy Assessment of Altimeter Derived Geostrophic Velocities

    NASA Astrophysics Data System (ADS)

    Leben, R. R.; Powell, B. S.; Born, G. H.; Guinasso, N. L.

    2002-12-01

    Along track sea surface height anomaly gradients are proportional to cross track geostrophic velocity anomalies allowing satellite altimetry to provide much needed satellite observations of changes in the geostrophic component of surface ocean currents. Often, surface height gradients are computed from altimeter data archives that have been corrected to give the most accurate absolute sea level, a practice that may unnecessarily increase the error in the cross track velocity anomalies and thereby require excessive smoothing to mitigate noise. Because differentiation along track acts as a high-pass filter, many of the path length corrections applied to altimeter data for absolute height accuracy are unnecessary for the corresponding gradient calculations. We report on a study to investigate appropriate altimetric corrections and processing techniques for improving geostrophic velocity accuracy. Accuracy is assessed by comparing cross track current measurements from two moorings placed along the descending TOPEX/POSEIDON ground track number 52 in the Gulf of Mexico to the corresponding altimeter velocity estimates. The buoys are deployed and maintained by the Texas Automated Buoy System (TABS) under Interagency Contracts with Texas A&M University. The buoys telemeter observations in near real-time via satellite to the TABS station located at the Geochemical and Environmental Research Group (GERG) at Texas A&M. Buoy M is located in shelf waters of 57 m depth with a second, Buoy N, 38 km away on the shelf break at 105 m depth. Buoy N has been operational since the beginning of 2002 and has a current meter at 2m depth providing in situ measurements of surface velocities coincident with Jason and TOPEX/POSEIDON altimeter over flights. This allows one of the first detailed comparisons of shallow water near surface current meter time series to coincident altimetry.

  18. 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.

  19. Simultaneous relative and absolute orientation of point clouds with "TLS radomes"

    NASA Astrophysics Data System (ADS)

    Glira, Philipp; Briese, Christian; Kamp, Nicole; Pfeifer, Norbert

    2013-04-01

    For the georeferencing of point clouds acquired by a terrestrial laser scanner (TLS) targets with known coordinates (control points) can be used. The determination of the target positions in a global coordinate frame with a total station and/or with GNSS can be very time-consuming. For multi-temporal comparison of TLS data these targets can be permanently installed on the measurement site. In permanent changing environments (e.g. high-moutain proglacial environments) this is not possible due to the movement of the targets. Furthermore, the integration of the TLS data with other data sources (e.g. airborne laser scanning data) has to be considered. For that aim the georeferencing of TLS measurements in a global coordinate frame has to be established. This work describes a new method for the simultaneous relative orientiation (registration) and absolute orientation (georeferencing) of point clouds by using spheres with a GNSS antenna inside. These spheres are thus used as GNSS antenna radomes. Consequently they are called within this work "TLS radomes". The simultaneous measurement with at least three GNSS antennas during the TLS data acquisition leads to long measurement times, i.e. high position accuracy and subsequently a very accurate realization of the datum. The presented TLS radomes consist of two hemispheres of polyethene enclosing the GNSS antenna. The GNSS antenna is mounted on an antenna rod, which can be enhanced by a prism and/or a reflective cylinder. For a modified optical reflectivity several coatings were tested. The one causing the smallest deformations, the smallest noise, and with the highest reflectivity was chosen. The whole construction can be mounted on a tripod. The TLS radomes are suitable for a wide range of different TLS sensors (i.e. independent of the ranging principle and the manufacturers). For the simultaneous relative and absolute orientation of the point clouds the centers of the radomes are used as identical points. With TLS these

  20. Seasonal Effects on GPS PPP Accuracy

    NASA Astrophysics Data System (ADS)

    Saracoglu, Aziz; Ugur Sanli, D.

    2016-04-01

    GPS Precise Point Positioning (PPP) is now routinely used in many geophysical applications. Static positioning and 24 h data are requested for high precision results however real life situations do not always let us collect 24 h data. Thus repeated GPS surveys of 8-10 h observation sessions are still used by some research groups. Positioning solutions from shorter data spans are subject to various systematic influences, and the positioning quality as well as the estimated velocity is degraded. Researchers pay attention to the accuracy of GPS positions and of the estimated velocities derived from short observation sessions. Recently some research groups turned their attention to the study of seasonal effects (i.e. meteorological seasons) on GPS solutions. Up to now usually regional studies have been reported. In this study, we adopt a global approach and study the various seasonal effects (including the effect of the annual signal) on GPS solutions produced from short observation sessions. We use the PPP module of the NASA/JPL's GIPSY/OASIS II software and globally distributed GPS stations' data of the International GNSS Service. Accuracy studies previously performed with 10-30 consecutive days of continuous data. Here, data from each month of a year, incorporating two years in succession, is used in the analysis. Our major conclusion is that a reformulation for the GPS positioning accuracy is necessary when taking into account the seasonal effects, and typical one term accuracy formulation is expanded to a two-term one.

  1. The Good Judge of Personality: Characteristics, Behaviors, and Observer Accuracy

    PubMed Central

    Letzring, Tera D.

    2008-01-01

    Personality characteristics and behaviors related to judgmental accuracy following unstructured interactions among previously unacquainted triads were examined. Judgmental accuracy was related to social skill, agreeableness, and adjustment. Accuracy of observers of the interactions was positively related to the number of good judges in the interaction, which implies that the personality and behaviors of the judge are important for creating a situation in which targets will reveal relevant personality cues. Furthermore, the finding that observer accuracy was positively related to the number of good judge partners suggests that judgmental accuracy is based on more than detection and utilization skills of the judge. PMID:19649134

  2. Measurement of absolute T cell receptor rearrangement diversity.

    PubMed

    Baum, Paul D; Young, Jennifer J; McCune, Joseph M

    2011-05-31

    T cell receptor (TCR) diversity is critical for adaptive immunity. Existing methods for measuring such diversity are qualitative, expensive, and/or of uncertain accuracy. Here, we describe a method and associated reagents for estimating the absolute number of unique TCR Vβ rearrangements present in a given number of cells or volume of blood. Compared to next generation sequencing, this method is rapid, reproducible, and affordable. Diversity of a sample is calculated based on three independent measurements of one Vβ-Jβ family of TCR rearrangements at a time. The percentage of receptors using the given Vβ gene is determined by flow cytometric analysis of T cells stained with anti-Vβ family antibodies. The percentage of receptors using the Vβ gene in combination with the chosen Jβ gene is determined by quantitative PCR. Finally, the absolute clonal diversity of the Vβ-Jβ family is determined with the AmpliCot method of DNA hybridization kinetics, by interpolation relative to PCR standards of known sequence diversity. These three component measurements are reproducible and linear. Using titrations of known numbers of input cells, we show that the TCR diversity estimates obtained by this approach approximate expected values within a two-fold error, have a coefficient of variation of 20%, and yield similar results when different Vβ-Jβ pairs are chosen. The ability to obtain accurate measurements of the total number of different TCR gene rearrangements in a cell sample should be useful for basic studies of the adaptive immune system as well as in clinical studies of conditions such as HIV disease, transplantation, aging, and congenital immunodeficiencies. PMID:21385585

  3. Accuracy Analysis and Validation of the Mars Science Laboratory (MSL) Robotic Arm

    NASA Technical Reports Server (NTRS)

    Collins, Curtis L.; Robinson, Matthew L.

    2013-01-01

    The Mars Science Laboratory (MSL) Curiosity Rover is currently exploring the surface of Mars with a suite of tools and instruments mounted to the end of a five degree-of-freedom robotic arm. To verify and meet a set of end-to-end system level accuracy requirements, a detailed positioning uncertainty model of the arm was developed and exercised over the arm operational workspace. Error sources at each link in the arm kinematic chain were estimated and their effects propagated to the tool frames.A rigorous test and measurement program was developed and implemented to collect data to characterize and calibrate the kinematic and stiffness parameters of the arm. Numerous absolute and relative accuracy and repeatability requirements were validated with a combination of analysis and test data extrapolated to the Mars gravity and thermal environment. Initial results of arm accuracy and repeatability on Mars demonstrate the effectiveness of the modeling and test program as the rover continues to explore the foothills of Mount Sharp.

  4. Swarm Absolute Scalar Magnetometers first in-orbit results

    NASA Astrophysics Data System (ADS)

    Fratter, Isabelle; Léger, Jean-Michel; Bertrand, François; Jager, Thomas; Hulot, Gauthier; Brocco, Laura; Vigneron, Pierre

    2016-04-01

    The ESA Swarm mission will provide the best ever survey of the Earth's magnetic field and its temporal evolution. This will be achieved by a constellation of three identical satellites, launched together on the 22nd of November 2013. In order to observe the magnetic field thoroughly, each satellite carries two magnetometers: a Vector Field Magnetometer (VFM) coupled with a star tracker camera, to measure the direction of the magnetic field in space, and an Absolute Scalar Magnetometer (ASM), to measure its intensity. The ASM is the French contribution to the Swarm mission. This new generation instrument was designed by CEA-Leti and developed in close partnership with CNES, with scientific support from IPGP. Its operating principle is based on the atomic spectroscopy of the helium 4 metastable state. It makes use of the Zeeman's effect to transduce the magnetic field into a frequency, the signal being amplified by optical pumping. The primary role of the ASM is to provide absolute measurements of the magnetic field's strength at 1 Hz, for the in-flight calibration of the VFM. As the Swarm magnetic reference, the ASM scalar performance is crucial for the mission's success. Thanks to its innovative design, the ASM offers the best precision, resolution and absolute accuracy ever attained in space, with similar performance all along the orbit. In addition, thanks to an original architecture, the ASM implements on an experimental basis a capacity for providing simultaneously vector measurements at 1 Hz. This new feature makes it the first instrument capable of delivering both scalar and vector measurements simultaneously at the same point. Swarm offers a unique opportunity to validate the ASM vector data in orbit by comparison with the VFM's. Furthermore, the ASM can provide scalar data at a much higher sampling rate, when run in "burst" mode at 250 Hz, with a 100 Hz measurement bandwidth. An analysis of the spectral content of the magnetic field above 1 Hz becomes thus

  5. Clock time is absolute and universal

    NASA Astrophysics Data System (ADS)

    Shen, Xinhang

    2015-09-01

    A critical error is found in the Special Theory of Relativity (STR): mixing up the concepts of the STR abstract time of a reference frame and the displayed time of a physical clock, which leads to use the properties of the abstract time to predict time dilation on physical clocks and all other physical processes. Actually, a clock can never directly measure the abstract time, but can only record the result of a physical process during a period of the abstract time such as the number of cycles of oscillation which is the multiplication of the abstract time and the frequency of oscillation. After Lorentz Transformation, the abstract time of a reference frame expands by a factor gamma, but the frequency of a clock decreases by the same factor gamma, and the resulting multiplication i.e. the displayed time of a moving clock remains unchanged. That is, the displayed time of any physical clock is an invariant of Lorentz Transformation. The Lorentz invariance of the displayed times of clocks can further prove within the framework of STR our earth based standard physical time is absolute, universal and independent of inertial reference frames as confirmed by both the physical fact of the universal synchronization of clocks on the GPS satellites and clocks on the earth, and the theoretical existence of the absolute and universal Galilean time in STR which has proved that time dilation and space contraction are pure illusions of STR. The existence of the absolute and universal time in STR has directly denied that the reference frame dependent abstract time of STR is the physical time, and therefore, STR is wrong and all its predictions can never happen in the physical world.

  6. Absolute calibration of the Auger fluorescence detectors

    SciTech Connect

    Bauleo, P.; Brack, J.; Garrard, L.; Harton, J.; Knapik, R.; Meyhandan, R.; Rovero, A.C.; Tamashiro, A.; Warner, D.

    2005-07-01

    Absolute calibration of the Pierre Auger Observatory fluorescence detectors uses a light source at the telescope aperture. The technique accounts for the combined effects of all detector components in a single measurement. The calibrated 2.5 m diameter light source fills the aperture, providing uniform illumination to each pixel. The known flux from the light source and the response of the acquisition system give the required calibration for each pixel. In the lab, light source uniformity is studied using CCD images and the intensity is measured relative to NIST-calibrated photodiodes. Overall uncertainties are presently 12%, and are dominated by systematics.

  7. Absolute rate theories of epigenetic stability

    NASA Astrophysics Data System (ADS)

    Walczak, Aleksandra M.; Onuchic, José N.; Wolynes, Peter G.

    2005-12-01

    Spontaneous switching events in most characterized genetic switches are rare, resulting in extremely stable epigenetic properties. We show how simple arguments lead to theories of the rate of such events much like the absolute rate theory of chemical reactions corrected by a transmission factor. Both the probability of the rare cellular states that allow epigenetic escape and the transmission factor depend on the rates of DNA binding and unbinding events and on the rates of protein synthesis and degradation. Different mechanisms of escape from the stable attractors occur in the nonadiabatic, weakly adiabatic, and strictly adiabatic regimes, characterized by the relative values of those input rates. rate theory | stochastic gene expression | gene switches

  8. Characterization of the DARA solar absolute radiometer

    NASA Astrophysics Data System (ADS)

    Finsterle, W.; Suter, M.; Fehlmann, A.; Kopp, G.

    2011-12-01

    The Davos Absolute Radiometer (DARA) prototype is an Electrical Substitution Radiometer (ESR) which has been developed as a successor of the PMO6 type on future space missions and ground based TSI measurements. The DARA implements an improved thermal design of the cavity detector and heat sink assembly to minimize air-vacuum differences and to maximize thermal symmetry of measuring and compensating cavity. The DARA also employs an inverted viewing geometry to reduce internal stray light. We will report on the characterization and calibration experiments which were carried out at PMOD/WRC and LASP (TRF).

  9. Absolute Priority for a Vehicle in VANET

    NASA Astrophysics Data System (ADS)

    Shirani, Rostam; Hendessi, Faramarz; Montazeri, Mohammad Ali; Sheikh Zefreh, Mohammad

    In today's world, traffic jams waste hundreds of hours of our life. This causes many researchers try to resolve the problem with the idea of Intelligent Transportation System. For some applications like a travelling ambulance, it is important to reduce delay even for a second. In this paper, we propose a completely infrastructure-less approach for finding shortest path and controlling traffic light to provide absolute priority for an emergency vehicle. We use the idea of vehicular ad-hoc networking to reduce the imposed travelling time. Then, we simulate our proposed protocol and compare it with a centrally controlled traffic light system.

  10. Absolute method of measuring magnetic susceptibility

    USGS Publications Warehouse

    Thorpe, A.; Senftle, F.E.

    1959-01-01

    An absolute method of standardization and measurement of the magnetic susceptibility of small samples is presented which can be applied to most techniques based on the Faraday method. The fact that the susceptibility is a function of the area under the curve of sample displacement versus distance of the magnet from the sample, offers a simple method of measuring the susceptibility without recourse to a standard sample. Typical results on a few substances are compared with reported values, and an error of less than 2% can be achieved. ?? 1959 The American Institute of Physics.

  11. Assessing the Accuracy of Alaska National Hydrography Data for Mapping and Science

    NASA Astrophysics Data System (ADS)

    Arundel, S. T.; Yamamoto, K. H.; Mantey, K.; Vinyard-Houx, J.; Miller-Corbett, C. D.

    2012-12-01

    In July, 2011, the National Geospatial Program embarked on a large-scale Alaska Topographic Mapping Initiative. Maps will be published through the USGS US Topo program. Mapping of the state requires an understanding of the spatial quality of the National Hydrography Dataset (NHD), which is the hydrographic source for the US Topo. The NHD in Alaska was originally produced from topographic maps at 1:63,360 scale. It is critical to determine whether the NHD is accurate enough to be represented at the targeted map scale of the US Topo (1:25,000). Concerns are the spatial accuracy of data and the density of the stream network. Unsuitably low accuracy can be a result of the lower positional accuracy standards required for the original 1:63,360 scale mapping, temporal changes in water features, or any combination of these factors. Insufficient positional accuracy results in poor vertical integration with data layers of higher positional accuracy. Poor integration is readily apparent on the US Topo, particularly relative to current imagery and elevation data. In Alaska, current IFSAR-derived digital terrain models meet positional accuracy requirements for 1:24,000-scale mapping. Initial visual assessments indicate a wide range in the quality of fit between features in NHD and the IFSAR. However, no statistical analysis had been performed to quantify NHD feature accuracy. Determining the absolute accuracy is cost prohibitive, because of the need to collect independent, well-defined test points for such analysis; however, quantitative analysis of relative positional error is a feasible alternative. The purpose of this study is to determine the baseline accuracy of Alaska NHD pertinent to US Topo production, and to recommend reasonable guidelines and costs for NHD improvement and updates. A second goal is to detect error trends that might help identify areas or features where data improvements are most needed. There are four primary objectives of the study: 1. Choose study

  12. Critical thinking and accuracy of nurses' diagnoses.

    PubMed

    Lunney, Margaret

    2003-01-01

    Interpretations of patient data are complex and diverse, contributing to a risk of low accuracy nursing diagnoses. This risk is confirmed in research findings that accuracy of nurses' diagnoses varied widely from high to low. Highly accurate diagnoses are essential, however, to guide nursing interventions for the achievement of positive health outcomes. Development of critical thinking abilities is likely to improve accuracy of nurses' diagnoses. New views of critical thinking serve as a basis for critical thinking in nursing. Seven cognitive skills and ten habits of mind are identified as dimensions of critical thinking for use in the diagnostic process. Application of the cognitive skills of critical thinking illustrates the importance of using critical thinking for accuracy of nurses' diagnoses. Ten strategies are proposed for self-development of critical thinking abilities.

  13. Optimal design of robot accuracy compensators

    SciTech Connect

    Zhuang, H.; Roth, Z.S. . Robotics Center and Electrical Engineering Dept.); Hamano, Fumio . Dept. of Electrical Engineering)

    1993-12-01

    The problem of optimal design of robot accuracy compensators is addressed. Robot accuracy compensation requires that actual kinematic parameters of a robot be previously identified. Additive corrections of joint commands, including those at singular configurations, can be computed without solving the inverse kinematics problem for the actual robot. This is done by either the damped least-squares (DLS) algorithm or the linear quadratic regulator (LQR) algorithm, which is a recursive version of the DLS algorithm. The weight matrix in the performance index can be selected to achieve specific objectives, such as emphasizing end-effector's positioning accuracy over orientation accuracy or vice versa, or taking into account proximity to robot joint travel limits and singularity zones. The paper also compares the LQR and the DLS algorithms in terms of computational complexity, storage requirement, and programming convenience. Simulation results are provided to show the effectiveness of the algorithms.

  14. Absolute Electron Extraction Efficiency of Liquid Xenon

    NASA Astrophysics Data System (ADS)

    Kamdin, Katayun; Mizrachi, Eli; Morad, James; Sorensen, Peter

    2016-03-01

    Dual phase liquid/gas xenon time projection chambers (TPCs) currently set the world's most sensitive limits on weakly interacting massive particles (WIMPs), a favored dark matter candidate. These detectors rely on extracting electrons from liquid xenon into gaseous xenon, where they produce proportional scintillation. The proportional scintillation from the extracted electrons serves to internally amplify the WIMP signal; even a single extracted electron is detectable. Credible dark matter searches can proceed with electron extraction efficiency (EEE) lower than 100%. However, electrons systematically left at the liquid/gas boundary are a concern. Possible effects include spontaneous single or multi-electron proportional scintillation signals in the gas, or charging of the liquid/gas interface or detector materials. Understanding EEE is consequently a serious concern for this class of rare event search detectors. Previous EEE measurements have mostly been relative, not absolute, assuming efficiency plateaus at 100%. I will present an absolute EEE measurement with a small liquid/gas xenon TPC test bed located at Lawrence Berkeley National Laboratory.

  15. Why to compare absolute numbers of mitochondria.

    PubMed

    Schmitt, Sabine; Schulz, Sabine; Schropp, Eva-Maria; Eberhagen, Carola; Simmons, Alisha; Beisker, Wolfgang; Aichler, Michaela; Zischka, Hans

    2014-11-01

    Prompted by pronounced structural differences between rat liver and rat hepatocellular carcinoma mitochondria, we suspected these mitochondrial populations to differ massively in their molecular composition. Aiming to reveal these mitochondrial differences, we came across the issue on how to normalize such comparisons and decided to focus on the absolute number of mitochondria. To this end, fluorescently stained mitochondria were quantified by flow cytometry. For rat liver mitochondria, this approach resulted in mitochondrial protein contents comparable to earlier reports using alternative methods. We determined similar protein contents for rat liver, heart and kidney mitochondria. In contrast, however, lower protein contents were determined for rat brain mitochondria and for mitochondria from the rat hepatocellular carcinoma cell line McA 7777. This result challenges mitochondrial comparisons that rely on equal protein amounts as a typical normalization method. Exemplarily, we therefore compared the activity and susceptibility toward inhibition of complex II of rat liver and hepatocellular carcinoma mitochondria and obtained significant discrepancies by either normalizing to protein amount or to absolute mitochondrial number. Importantly, the latter normalization, in contrast to the former, demonstrated a lower complex II activity and higher susceptibility toward inhibition in hepatocellular carcinoma mitochondria compared to liver mitochondria. These findings demonstrate that solely normalizing to protein amount may obscure essential molecular differences between mitochondrial populations.

  16. Relational versus absolute representation in categorization.

    PubMed

    Edwards, Darren J; Pothos, Emmanuel M; Perlman, Amotz

    2012-01-01

    This study explores relational-like and absolute-like representations in categorization. Although there is much evidence that categorization processes can involve information about both the particular physical properties of studied instances and abstract (relational) properties, there has been little work on the factors that lead to one kind of representation as opposed to the other. We tested 370 participants in 6 experiments, in which participants had to classify new items into predefined artificial categories. In 4 experiments, we observed a predominantly relational-like mode of classification, and in 2 experiments we observed a shift toward an absolute-like mode of classification. These results suggest 3 factors that promote a relational-like mode of classification: fewer items per group, more training groups, and the presence of a time delay. Overall, we propose that less information about the distributional properties of a category or weaker memory traces for the category exemplars (induced, e.g., by having smaller categories or a time delay) can encourage relational-like categorization.

  17. Transient absolute robustness in stochastic biochemical networks.

    PubMed

    Enciso, German A

    2016-08-01

    Absolute robustness allows biochemical networks to sustain a consistent steady-state output in the face of protein concentration variability from cell to cell. This property is structural and can be determined from the topology of the network alone regardless of rate parameters. An important question regarding these systems is the effect of discrete biochemical noise in the dynamical behaviour. In this paper, a variable freezing technique is developed to show that under mild hypotheses the corresponding stochastic system has a transiently robust behaviour. Specifically, after finite time the distribution of the output approximates a Poisson distribution, centred around the deterministic mean. The approximation becomes increasingly accurate, and it holds for increasingly long finite times, as the total protein concentrations grow to infinity. In particular, the stochastic system retains a transient, absolutely robust behaviour corresponding to the deterministic case. This result contrasts with the long-term dynamics of the stochastic system, which eventually must undergo an extinction event that eliminates robustness and is completely different from the deterministic dynamics. The transiently robust behaviour may be sufficient to carry out many forms of robust signal transduction and cellular decision-making in cellular organisms. PMID:27581485

  18. EOS mapping accuracy study

    NASA Technical Reports Server (NTRS)

    Forrest, R. B.; Eppes, T. A.; Ouellette, R. J.

    1973-01-01

    Studies were performed to evaluate various image positioning methods for possible use in the earth observatory satellite (EOS) program and other earth resource imaging satellite programs. The primary goal is the generation of geometrically corrected and registered images, positioned with respect to the earth's surface. The EOS sensors which were considered were the thematic mapper, the return beam vidicon camera, and the high resolution pointable imager. The image positioning methods evaluated consisted of various combinations of satellite data and ground control points. It was concluded that EOS attitude control system design must be considered as a part of the image positioning problem for EOS, along with image sensor design and ground image processing system design. Study results show that, with suitable efficiency for ground control point selection and matching activities during data processing, extensive reliance should be placed on use of ground control points for positioning the images obtained from EOS and similar programs.

  19. What do we mean by accuracy in geomagnetic measurements?

    USGS Publications Warehouse

    Green, A.W.

    1990-01-01

    High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

  20. A Conceptual Approach to Absolute Value Equations and Inequalities

    ERIC Educational Resources Information Center

    Ellis, Mark W.; Bryson, Janet L.

    2011-01-01

    The absolute value learning objective in high school mathematics requires students to solve far more complex absolute value equations and inequalities. When absolute value problems become more complex, students often do not have sufficient conceptual understanding to make any sense of what is happening mathematically. The authors suggest that the…

  1. Using, Seeing, Feeling, and Doing Absolute Value for Deeper Understanding

    ERIC Educational Resources Information Center

    Ponce, Gregorio A.

    2008-01-01

    Using sticky notes and number lines, a hands-on activity is shared that anchors initial student thinking about absolute value. The initial point of reference should help students successfully evaluate numeric problems involving absolute value. They should also be able to solve absolute value equations and inequalities that are typically found in…

  2. High accuracy OMEGA timekeeping

    NASA Technical Reports Server (NTRS)

    Imbier, E. A.

    1982-01-01

    The Smithsonian Astrophysical Observatory (SAO) operates a worldwide satellite tracking network which uses a combination of OMEGA as a frequency reference, dual timing channels, and portable clock comparisons to maintain accurate epoch time. Propagational charts from the U.S. Coast Guard OMEGA monitor program minimize diurnal and seasonal effects. Daily phase value publications of the U.S. Naval Observatory provide corrections to the field collected timing data to produce an averaged time line comprised of straight line segments called a time history file (station clock minus UTC). Depending upon clock location, reduced time data accuracies of between two and eight microseconds are typical.

  3. Choice deferral can arise from absolute evaluations or relative comparisons.

    PubMed

    White, Chris M; Hoffrage, Ulrich; Reisen, Nils

    2015-06-01

    When choosing among several options, people may defer choice for either of 2 reasons: because none of the options is good enough or because there is uncertainty regarding which is the best. These reasons form the basis of the 2-stage, 2-threshold (2S2T) framework, which posits that a different kind of processing corresponds to these 2 reasons for choice deferral: absolute evaluations and relative comparisons, respectively. Three experiments are reported in which each type of processing was triggered in different conditions either via different payoff structures or different degrees of attribute knowledge. The effects of the 3 main independent variables (the size of the choice set, the utility of the best option, and the number of competitive options) differed depending on the payoff structure or attribute knowledge conditions in ways predicted by the 2S2T framework. Implications for consumer decision making, marketing, and eyewitness identification are discussed. PMID:25938974

  4. The preference of visualization in teaching and learning absolute value

    NASA Astrophysics Data System (ADS)

    Cihan Konyalioğlu, Alper; Aksu, Zeki; Özge Şenel, Esma

    2012-07-01

    Visualization is mostly despised although it complements and - sometimes - guides the analytical process. This study mainly investigates teachers' preferences concerning the use of the visualization method and determines the extent to which they encourage their students to make use of it within the problem-solving process. This study was conducted for the ninth-grade students and their mathematics teacher in a social science intensive public school in the city of Erzurum, Turkey. Utilizing case study as the preferred method, data were collected through observations, interviews and student evaluations. This study revealed that visualization has a positive effect at the preliminary phases of teaching the absolute value concept but generates a lack of stimulation during problem solving in further phases of the instruction. This could be explained as a result of current examination system which requires a habituation of the analytical process in solving mathematical questions.

  5. Absolute Pitch: Effects of Timbre on Note-Naming Ability

    PubMed Central

    Vanzella, Patrícia; Schellenberg, E. Glenn

    2010-01-01

    Background Absolute pitch (AP) is the ability to identify or produce isolated musical tones. It is evident primarily among individuals who started music lessons in early childhood. Because AP requires memory for specific pitches as well as learned associations with verbal labels (i.e., note names), it represents a unique opportunity to study interactions in memory between linguistic and nonlinguistic information. One untested hypothesis is that the pitch of voices may be difficult for AP possessors to identify. A musician's first instrument may also affect performance and extend the sensitive period for acquiring accurate AP. Methods/Principal Findings A large sample of AP possessors was recruited on-line. Participants were required to identity test tones presented in four different timbres: piano, pure tone, natural (sung) voice, and synthesized voice. Note-naming accuracy was better for non-vocal (piano and pure tones) than for vocal (natural and synthesized voices) test tones. This difference could not be attributed solely to vibrato (pitch variation), which was more pronounced in the natural voice than in the synthesized voice. Although starting music lessons by age 7 was associated with enhanced note-naming accuracy, equivalent abilities were evident among listeners who started music lessons on piano at a later age. Conclusions/Significance Because the human voice is inextricably linked to language and meaning, it may be processed automatically by voice-specific mechanisms that interfere with note naming among AP possessors. Lessons on piano or other fixed-pitch instruments appear to enhance AP abilities and to extend the sensitive period for exposure to music in order to develop accurate AP. PMID:21085598

  6. Absolutism and Natural Law Argument: William O. Douglas on Freedom of Expression.

    ERIC Educational Resources Information Center

    Rodgers, Raymond S.

    Noting that United States Supreme Court Justice William O. Douglas has often been characterized as an "absolutist" in terms of First Amendment policy, this paper argues that, in fact, Douglas's policy positions provided for less than absolute freedom to communicate. The paper then reveals, through an anlaysis of 18 of Douglas's opinions, an…

  7. Ridge-spotting: A new test for Pacific absolute plate motion models

    NASA Astrophysics Data System (ADS)

    Wessel, Paul; Müller, R. Dietmar

    2016-06-01

    Relative plate motions provide high-resolution descriptions of motions of plates relative to other plates. Yet geodynamically, motions of plates relative to the mantle are required since such motions can be attributed to forces (e.g., slab pull and ridge push) acting upon the plates. Various reference frames have been proposed, such as the hot spot reference frame, to link plate motions to a mantle framework. Unfortunately, both accuracy and precision of absolute plate motion models lag behind those of relative plate motion models. Consequently, it is paramount to use relative plate motions in improving our understanding of absolute plate motions. A new technique called "ridge-spotting" combines absolute and relative plate motions and examines the viability of proposed absolute plate motion models. We test the method on six published Pacific absolute plate motions models, including fixed and moving hot spot models as well as a geodynamically derived model. Ridge-spotting reconstructs the Pacific-Farallon and Pacific-Antarctica ridge systems over the last 80 Myr. All six absolute plate motion models predict large amounts of northward migration and monotonic clockwise rotation for the Pacific-Farallon ridge. A geodynamic implication of our ridge migration predictions is that the suggestion that the Pacific-Farallon ridge may have been pinned by a large mantle upwelling is not supported. Unexpected or erratic ridge behaviors may be tied to limitations in the models themselves or (for Indo-Atlantic models) discrepancies in the plate circuits used to project models into the Pacific realm. Ridge-spotting is promising and will be extended to include more plates and other ocean basins.

  8. Noninvasive absolute cerebral oximetry with frequency-domain near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Hallacoglu, Bertan

    Near-infrared spectroscopy (NIRS) measurements of absolute concentrations of oxy-hemoglobin and deoxy-hemoglobin in the human brain can provide critical information about cerebral physiology in terms of cerebral blood volume, blood flow, oxygen delivery, and metabolic rate of oxygen. We developed several frequency domain NIRS data acquisition and analysis methods aimed at absolute measurements of hemoglobin concentration and saturation in cerebral tissue of adult human subjects. Extensive experimental investigations were carried out in various homogenous and two-layered tissue-mimicking phantoms, and biological tissues. The advantages and limitations of commonly used homogenous models and inversion strategies were thoroughly investigated. Prior to human subjects, extensive studies were carried out in in vivo animal models. In rabbits, absolute hemoglobin oxygen desaturation was shown to depend strongly on surgically induced testicular torsion. Methods developed in this study were then adapted for measurements in the rat brain. Absolute values were demonstrated to discern cerebrovascular impairment in a rat model of diet-induced vascular cognitive impairment. These results facilitated the development of clinically useful optical measures of cerebrovascular health. In a large group of human subjects, employing a homogeneous model for absolute measurements was shown to be reliable and robust. However, it was also shown to be limited due to the relatively thick extracerebral tissue. The procedure we develop in this work and the thesis thereof performs a nonlinear inversion procedure with six unknown parameters with no other prior knowledge for the retrieval of the optical coefficients and top layer thickness with high accuracy on two-layered media. Our absolute measurements of cerebral hemoglobin concentration and saturation are based on the discrimination of extracerebral and cerebral tissue layers, and they can enhance the impact of NIRS for cerebral hemodynamics and

  9. The Absolute Radiometric Calibration of Space - Sensors.

    NASA Astrophysics Data System (ADS)

    Holm, Ronald Gene

    1987-09-01

    The need for absolute radiometric calibration of space-based sensors will continue to increase as new generations of space sensors are developed. A reflectance -based in-flight calibration procedure is used to determine the radiance reaching the entrance pupil of the sensor. This procedure uses ground-based measurements coupled with a radiative transfer code to characterize the effects the atmosphere has on the signal reaching the sensor. The computed radiance is compared to the digital count output of the sensor associated with the image of a test site. This provides an update to the preflight calibration of the system and a check on the on-board internal calibrator. This calibration procedure was used to perform a series of five calibrations of the Landsat-5 Thematic Mapper (TM). For the 12 measurements made in TM bands 1-3, the RMS variation from the mean as a percentage of the mean is (+OR-) 1.9%, and for measurements in the IR, TM bands 4,5, and 7, the value is (+OR-) 3.4%. The RMS variation for all 23 measurements is (+OR-) 2.8%. The absolute calibration techniques were put to another test with a series of three calibration of the SPOT-1 High Resolution Visible, (HRV), sensors. The ratio, HRV-2/HRV-1, of absolute calibration coefficients compared very well with ratios of histogrammed data obtained when the cameras simultaneously imaged the same ground site. Bands PA, B1 and B3 agreed to within 3%, while band B2 showed a 7% difference. The procedure for performing a satellite calibration was then used to demonstrate how a calibrated satellite sensor can be used to quantitatively evaluate surface reflectance over a wide range of surface features. Predicted reflectance factors were compared to values obtained from aircraft -based radiometer data. This procedure was applied on four dates with two different surface conditions per date. A strong correlation, R('2) = .996, was shown between reflectance values determined from satellite imagery and low-flying aircraft

  10. Absolute localization of ground robots by matching LiDAR and image data in dense forested environments

    NASA Astrophysics Data System (ADS)

    Hussein, Marwan; Renner, Matthew; Iagnemma, Karl

    2014-06-01

    A method for the autonomous geolocation of ground vehicles in forest environments is discussed. The method provides an estimate of the global horizontal position of a vehicle strictly based on finding a geometric match between a map of observed tree stems, scanned in 3D by Light Detection and Ranging (LiDAR) sensors onboard the vehicle, to another stem map generated from the structure of tree crowns analyzed from high resolution aerial orthoimagery of the forest canopy. Extraction of stems from 3D data is achieved by using Support Vector Machine (SVM) classifiers and height above ground filters that separate ground points from vertical stem features. Identification of stems from overhead imagery is achieved by finding the centroids of tree crowns extracted using a watershed segmentation algorithm. Matching of the two maps is achieved by using a robust Iterative Closest Point (ICP) algorithm that determines the rotation and translation vectors to align the datasets. The alignment is used to calculate the absolute horizontal location of the vehicle. The method has been tested with real-world data and has been able to estimate vehicle geoposition with an average error of less than 2 m. It is noted that the algorithm's accuracy performance is currently limited by the accuracy and resolution of aerial orthoimagery used. The method can be used in real-time as a complement to the Global Positioning System (GPS) in areas where signal coverage is inadequate due to attenuation by the forest canopy, or due to intentional denied access. The method has two key properties that are significant: i) It does not require a priori knowledge of the area surrounding the robot. ii) Uses the geometry of detected tree stems as the only input to determine horizontal geoposition.

  11. Ground Truth Accuracy Tests of GPS Seismology

    NASA Astrophysics Data System (ADS)

    Elosegui, P.; Oberlander, D. J.; Davis, J. L.; Baena, R.; Ekstrom, G.

    2005-12-01

    As the precision of GPS determinations of site position continues to improve the detection of smaller and faster geophysical signals becomes possible. However, lack of independent measurements of these signals often precludes an assessment of the accuracy of such GPS position determinations. This may be particularly true for high-rate GPS applications. We have built an apparatus to assess the accuracy of GPS position determinations for high-rate applications, in particular the application known as "GPS seismology." The apparatus consists of a bidirectional, single-axis positioning table coupled to a digitally controlled stepping motor. The motor, in turn, is connected to a Field Programmable Gate Array (FPGA) chip that synchronously sequences through real historical earthquake profiles stored in Erasable Programmable Read Only Memory's (EPROM). A GPS antenna attached to this positioning table undergoes the simulated seismic motions of the Earth's surface while collecting high-rate GPS data. Analysis of the time-dependent position estimates can then be compared to the "ground truth," and the resultant GPS error spectrum can be measured. We have made extensive measurements with this system while inducing simulated seismic motions either in the horizontal plane or the vertical axis. A second stationary GPS antenna at a distance of several meters was simultaneously collecting high-rate (5 Hz) GPS data. We will present the calibration of this system, describe the GPS observations and data analysis, and assess the accuracy of GPS for high-rate geophysical applications and natural hazards mitigation.

  12. Use of Absolute and Comparative Performance Feedback in Absolute and Comparative Judgments and Decisions

    ERIC Educational Resources Information Center

    Moore, Don A.; Klein, William M. P.

    2008-01-01

    Which matters more--beliefs about absolute ability or ability relative to others? This study set out to compare the effects of such beliefs on satisfaction with performance, self-evaluations, and bets on future performance. In Experiment 1, undergraduate participants were told they had answered 20% correct, 80% correct, or were not given their…

  13. An absolute interval scale of order for point patterns

    PubMed Central

    Protonotarios, Emmanouil D.; Baum, Buzz; Johnston, Alan; Hunter, Ginger L.; Griffin, Lewis D.

    2014-01-01

    Human observers readily make judgements about the degree of order in planar arrangements of points (point patterns). Here, based on pairwise ranking of 20 point patterns by degree of order, we have been able to show that judgements of order are highly consistent across individuals and the dimension of order has an interval scale structure spanning roughly 10 just-notable-differences (jnd) between disorder and order. We describe a geometric algorithm that estimates order to an accuracy of half a jnd by quantifying the variability of the size and shape of spaces between points. The algorithm is 70% more accurate than the best available measures. By anchoring the output of the algorithm so that Poisson point processes score on average 0, perfect lattices score 10 and unit steps correspond closely to jnds, we construct an absolute interval scale of order. We demonstrate its utility in biology by using this scale to quantify order during the development of the pattern of bristles on the dorsal thorax of the fruit fly. PMID:25079866

  14. Scanning micro-resonator direct-comb absolute spectroscopy

    PubMed Central

    Gambetta, Alessio; Cassinerio, Marco; Gatti, Davide; Laporta, Paolo; Galzerano, Gianluca

    2016-01-01

    Direct optical Frequency Comb Spectroscopy (DFCS) is proving to be a fundamental tool in many areas of science and technology thanks to its unique performance in terms of ultra-broadband, high-speed detection and frequency accuracy, allowing for high-fidelity mapping of atomic and molecular energy structure. Here we present a novel DFCS approach based on a scanning Fabry-Pérot micro-cavity resonator (SMART) providing a simple, compact and accurate method to resolve the mode structure of an optical frequency comb. The SMART approach, while drastically reducing system complexity, allows for a straightforward absolute calibration of the optical-frequency axis with an ultimate resolution limited by the micro-resonator resonance linewidth and can be used in any spectral region from UV to THz. We present an application to high-precision spectroscopy of acetylene at 1.54 μm, demonstrating performances comparable or even better than current state-of-the-art DFCS systems in terms of sensitivity, optical bandwidth and frequency-resolution. PMID:27752132

  15. Alignment and absolute wavelength calibration of imaging Bragg spectrometers

    NASA Astrophysics Data System (ADS)

    Bertschinger, G.; Marchuk, O.; Barnsley, R.

    2016-11-01

    In the present and the next generation of fusion devices, imaging Bragg spectrometers are key diagnostics to measure plasma parameters in the hot core, especially ion temperature and plasma rotation. The latter quantities are routinely obtained using the Doppler-width and -shift of the emitted spectral lines, respectively. Line shift measurements require absolute accuracies Δλ/λ of about 10 ppm, where λ-is the observed wavelength. For ITER and the present fusion devices, spectral lines of He-and H-like argon, iron, and krypton as well as Ne-like tungsten are foreseen for the measurements. For these lines, Kα lines can be found, some in higher order, which fit into the narrow energy window of the spectrometers. For arbitrary wavelength settings, Kα lines are also used to measure the miscut of the spherical crystals; afterwards the spectrometers can be set according to the geometrical imaging properties using coordinate measurement machines. For the spectrometers measuring Lyα lines of H-like ions, fluorescence targets can provide in situ localized calibration lines on the spectra. The fluorescence targets are used best in transmission and are excited by the thermal x-ray radiation of the plasma. An analytic theory of fluorescence is worked out.

  16. Absolute radiometric calibration of the CCRS SAR

    NASA Astrophysics Data System (ADS)

    Ulander, Lars M. H.; Hawkins, Robert K.; Livingstone, Charles E.; Lukowski, Tom I.

    1991-11-01

    Determining the radar scattering coefficients from SAR (synthetic aperture radar) image data requires absolute radiometric calibration of the SAR system. The authors describe an internal calibration methodology for the airborne Canada Centre for Remote Sensing (CCRS) SAR system, based on radar theory, a detailed model of the radar system, and measurements of system parameters. The methodology is verified by analyzing external calibration data acquired over a 6-month period in 1988 by the C-band radar using HH polarization. The results indicate that the overall error is +/- 0.8 dB (1-sigma) for incidence angles +/- 20 deg from antenna boresight. The dominant error contributions are due to the antenna radome and uncertainties in the elevation angle relative to the antenna boresight.

  17. Absolute calibration of ultraviolet filter photometry

    NASA Technical Reports Server (NTRS)

    Bless, R. C.; Fairchild, T.; Code, A. D.

    1972-01-01

    The essential features of the calibration procedure can be divided into three parts. First, the shape of the bandpass of each photometer was determined by measuring the transmissions of the individual optical components and also by measuring the response of the photometer as a whole. Secondly, each photometer was placed in the essentially-collimated synchrotron radiation bundle maintained at a constant intensity level, and the output signal was determined from about 100 points on the objective. Finally, two or three points on the objective were illuminated by synchrotron radiation at several different intensity levels covering the dynamic range of the photometers. The output signals were placed on an absolute basis by the electron counting technique described earlier.

  18. Absolute measurements of fast neutrons using yttrium

    SciTech Connect

    Roshan, M. V.; Springham, S. V.; Rawat, R. S.; Lee, P.; Krishnan, M.

    2010-08-15

    Yttrium is presented as an absolute neutron detector for pulsed neutron sources. It has high sensitivity for detecting fast neutrons. Yttrium has the property of generating a monoenergetic secondary radiation in the form of a 909 keV gamma-ray caused by inelastic neutron interaction. It was calibrated numerically using MCNPX and does not need periodic recalibration. The total yttrium efficiency for detecting 2.45 MeV neutrons was determined to be f{sub n}{approx}4.1x10{sup -4} with an uncertainty of about 0.27%. The yttrium detector was employed in the NX2 plasma focus experiments and showed the neutron yield of the order of 10{sup 8} neutrons per discharge.

  19. Absolute geostrophic currents in global tropical oceans

    NASA Astrophysics Data System (ADS)

    Yang, Lina; Yuan, Dongliang

    2016-11-01

    A set of absolute geostrophic current (AGC) data for the period January 2004 to December 2012 are calculated using the P-vector method based on monthly gridded Argo profiles in the world tropical oceans. The AGCs agree well with altimeter geostrophic currents, Ocean Surface Current Analysis-Real time currents, and moored current-meter measurements at 10-m depth, based on which the classical Sverdrup circulation theory is evaluated. Calculations have shown that errors of wind stress calculation, AGC transport, and depth ranges of vertical integration cannot explain non-Sverdrup transport, which is mainly in the subtropical western ocean basins and equatorial currents near the Equator in each ocean basin (except the North Indian Ocean, where the circulation is dominated by monsoons). The identified non-Sverdrup transport is thereby robust and attributed to the joint effect of baroclinicity and relief of the bottom (JEBAR) and mesoscale eddy nonlinearity.

  20. Absolute Measurement of Electron Cloud Density

    SciTech Connect

    Covo, M K; Molvik, A W; Cohen, R H; Friedman, A; Seidl, P A; Logan, G; Bieniosek, F; Baca, D; Vay, J; Orlando, E; Vujic, J L

    2007-06-21

    Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 {micro}s duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LBNL.

  1. Absolute calibration of remote sensing instruments

    NASA Astrophysics Data System (ADS)

    Biggar, S. F.; Bruegge, C. J.; Capron, B. A.; Castle, K. R.; Dinguirard, M. C.; Holm, R. G.; Lingg, L. J.; Mao, Y.; Palmer, J. M.; Phillips, A. L.

    1985-12-01

    Source-based and detector-based methods for the absolute radiometric calibration of a broadband field radiometer are described. Using such a radiometer, calibrated by both methods, the calibration of the integrating sphere used in the preflight calibration of the Thematic Mapper was redetermined. The results are presented. The in-flight calibration of space remote sensing instruments is discussed. A method which uses the results of ground-based reflectance and atmospheric measurements as input to a radiative transfer code to predict the radiance at the instrument is described. A calibrated, helicopter-mounted radiometer is used to determine the radiance levels at intermediate altitudes to check the code predictions. Results of such measurements for the calibration of the Thematic Mapper on Landsat 5 and an analysis that shows the value of such measurements are described.

  2. Absolute radiometric calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.

    1986-01-01

    Calibration data for the solar reflective bands of the Landsat-5 TM obtained from five in-flight absolute radiometric calibrations from July 1984-November 1985 at White Sands, New Mexico are presented and analyzed. Ground reflectance and atmospheric data were utilized to predict the spectral radiance at the entrance pupil of the TM and the average number of digital counts in each TM band. The calibration of each of the TM solar reflective bands was calculated in terms of average digital counts/unit spectral radiance for each band. It is observed that for the 12 reflectance-based measurements the rms variation from the means as a percentage of the mean is + or - 1.9 percent; for the 11 measurements in the IR bands, it is + or - 3.4 percent; and the rms variation for all 23 measurements is + or - 2.8 percent.

  3. Test Plan for a Calibration Demonstration System for the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; McCorkel, Joel; Hair, Jason; McAndrew, Brendan; Daw, Adrian; Jennings, Donald; Rabin, Douglas

    2012-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe high-accuracy, long-term climate change trends and to use decadal change observations as the most critical method to determine the accuracy of climate change. One of the major objectives of CLARREO is to advance the accuracy of SI traceable absolute calibration at infrared and reflected solar wavelengths. This advance is required to reach the on-orbit absolute accuracy required to allow climate change observations to survive data gaps while remaining sufficiently accurate to observe climate change to within the uncertainty of the limit of natural variability. While these capabilities exist at NIST in the laboratory, there is a need to demonstrate that it can move successfully from NIST to NASA and/or instrument vendor capabilities for future spaceborne instruments. The current work describes the test plan for the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. The goal of the CDS is to allow the testing and evaluation of calibration approaches , alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. The end result of efforts with the SOLARIS CDS will be an SI-traceable error budget for reflectance retrieval using solar irradiance as a reference and methods for laboratory-based, absolute calibration suitable for climate-quality data collections. The CLARREO mission addresses the need to observe high-accuracy, long-term climate change trends and advance the accuracy of SI traceable absolute calibration. The current work describes the test plan for the SOLARIS which is the calibration demonstration

  4. Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography

    PubMed Central

    Qi, Li; Zhu, Jiang; Hancock, Aneeka M.; Dai, Cuixia; Zhang, Xuping; Frostig, Ron D.; Chen, Zhongping

    2016-01-01

    Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it is related to vessel geometry. In this paper, we present a volumetric vessel reconstruction approach that is capable of measuring the absolute BFV distributed along the entire middle cerebral artery (MCA) within a large field-of-view. The Doppler angle at each point of the MCA, representing the vessel geometry, is derived analytically by localizing the artery from pure DOCT images through vessel segmentation and skeletonization. Our approach could achieve automatic quantification of the fully distributed absolute BFV across different vessel branches. Experiments on rodents using swept-source optical coherence tomography showed that our approach was able to reveal the consequences of permanent MCA occlusion with absolute BFV measurement. PMID:26977365

  5. Position determination of a lander and rover at Mars with Earth-based differential tracking

    NASA Technical Reports Server (NTRS)

    Kahn, R. D.; Folkner, W. M.; Edwards, C. D.; Vijayaraghavan, A.

    1992-01-01

    The presence of two or more landed or orbiting spacecraft at a planet provides the opportunity to perform extremely accurate Earth-based navigation by simultaneously acquiring Doppler data and either Same-Beam Interferometry (SBI) or ranging data. Covariance analyses were performed to investigate the accuracy with which lander and rover positions on the surface of Mars can be determined. Simultaneous acquisition of Doppler and ranging data from a lander and rover over two or more days enables determination of all components of their relative position to under 20 m. Acquiring one hour of Doppler and SBI enables three dimensional lander-rover relative position determination to better than 5 m. Twelve hours of Doppler and either SBI or ranging from a lander and a low circular or half synchronous circular Mars orbiter makes possible lander absolute position determination to tens of meters.

  6. Assessment of the Geodetic and Color Accuracy of Multi-Pass Airborne/Mobile Lidar Data

    NASA Astrophysics Data System (ADS)

    Pack, R. T.; Petersen, B.; Sunderland, D.; Blonquist, K.; Israelsen, P.; Crum, G.; Fowles, A.; Neale, C.

    2008-12-01

    The ability to merge lidar and color image data acquired by multiple passes of an aircraft or van is largely dependent on the accuracy of the navigation system that estimates the dynamic position and orientation of the sensor. We report an assessment of the performance of a Riegl Q560 lidar transceiver combined with a Litton LN-200 inertial measurement unit (IMU) based NovAtel SPAN GPS/IMU system and a Panasonic HD Video Camera system. Several techniques are reported that were used to maximize the performance of the GPS/IMU system in generating precisely merged point clouds. The airborne data used included eight flight lines all overflying the same building on the campus at Utah State University. These lines were flown at the FAA minimum altitude of 1000 feet for fixed-wing aircraft. The mobile data was then acquired with the same system mounted to look sideways out of a van several months later. The van was driven around the same building at variable speed in order to avoid pedestrians. An absolute accuracy of about 6 cm and a relative accuracy of less than 2.5 cm one-sigma are documented for the merged data. Several techniques are also reported for merging of the color video data stream with the lidar point cloud. A technique for back-projecting and burning lidar points within the video stream enables the verification of co-boresighting accuracy. The resulting pixel-level alignment is accurate with within the size of a lidar footprint. The techniques described in this paper enable the display of high-resolution colored points of high detail and color clarity.

  7. Calibration of the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; Barnes, Robert; Baize, Rosemary; O'Connell, Joseph; Hair, Jason

    2010-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) plans to observe climate change trends over decadal time scales to determine the accuracy of climate projections. The project relies on spaceborne earth observations of SI-traceable variables sensitive to key decadal change parameters. The mission includes a reflected solar instrument retrieving at-sensor reflectance over the 320 to 2300 nm spectral range with 500-m spatial resolution and 100-km swath. Reflectance is obtained from the ratio of measurements of the earth s surface to those while viewing the sun relying on a calibration approach that retrieves reflectance with uncertainties less than 0.3%. The calibration is predicated on heritage hardware, reduction of sensor complexity, adherence to detector-based calibration standards, and an ability to simulate in the laboratory on-orbit sources in both size and brightness to provide the basis of a transfer to orbit of the laboratory calibration including a link to absolute solar irradiance measurements.

  8. Absolute brightness temperature measurements at 3.5-mm wavelength. [of sun, Venus, Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Ulich, B. L.; Rhodes, P. J.; Davis, J. H.; Hollis, J. M.

    1980-01-01

    Careful observations have been made at 86.1 GHz to derive the absolute brightness temperatures of the sun (7914 + or - 192 K), Venus (357.5 + or - 13.1 K), Jupiter (179.4 + or - 4.7 K), and Saturn (153.4 + or - 4.8 K) with a standard error of about three percent. This is a significant improvement in accuracy over previous results at millimeter wavelengths. A stable transmitter and novel superheterodyne receiver were constructed and used to determine the effective collecting area of the Millimeter Wave Observatory (MWO) 4.9-m antenna relative to a previously calibrated standard gain horn. The thermal scale was set by calibrating the radiometer with carefully constructed and tested hot and cold loads. The brightness temperatures may be used to establish an absolute calibration scale and to determine the antenna aperture and beam efficiencies of other radio telescopes at 3.5-mm wavelength.

  9. Absolutely calibrated soft-x-ray streak camera for laser-fusion applications

    SciTech Connect

    Kauffman, R.L.; Medecki, H.; Stradling, G.

    1982-01-01

    The intensity output of a soft-x-ray streak camera was calibrated (SXRSC) in order to make absolute flux measurements of x rays emitted from laser-produced plasmas. The SXRSC developed at LLNL is used to time-resolve x-ray pulses to better than 20 ps. The SXRSC uses a Au photocathode on a thin carbon substrate which is sensitive to x rays from 100 eV to greater than 10 keV. Calibrations are done in the dynamic mode using a small laser-produced x-ray source. The SXRSC is calibrated by comparing its integrated signal to the output of calibrated x-ray diodes monitoring the source strength. The measured SXRSC response is linear over greater than two orders of magnitude. Using these calibrations, absolute intensities can be measured to an accuracy of +-30%.

  10. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B.; Lubin, L.

    2004-07-01

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the rms scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.04 magnitudes, with some dependence on filter. The largest errors seen are 0.07 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  11. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B.; Lubin, L.

    2002-12-01

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the mean scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.04 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  12. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B. C.; Lubin, L. M.

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the mean scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The tentative agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.03 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  13. Absolute Geodetic Rotation Measurement Using Atom Interferometry

    SciTech Connect

    Stockton, J. K.; Takase, K.; Kasevich, M. A.

    2011-09-23

    We demonstrate a cold-atom interferometer gyroscope which overcomes accuracy and dynamic range limitations of previous atom interferometer gyroscopes. We show how the instrument can be used for precise determination of latitude, azimuth (true north), and Earth's rotation rate. Spurious noise terms related to multiple-path interferences are suppressed by employing a novel time-skewed pulse sequence. Extended versions of this instrument appear capable of meeting the stringent requirements for inertial navigation, geodetic applications of Earth's rotation rate determination, and tests of general relativity.

  14. On the absolute alignment of GONG images

    NASA Astrophysics Data System (ADS)

    Toner, C. G.

    2001-01-01

    In order to combine data from the six instruments in the GONG network the alignment of all of the images must be known to a fairly high precision (~0°.1 for GONG Classic and ~0°.01 for GONG+). The relative orientation is obtained using the angular cross-correlation method described by (Toner & Harvey, 1998). To obtain the absolute orientation the Project periodically records a day of drift scans, where the image of the Sun is allowed to drift across the CCD repeatedly throughout the day. These data are then analyzed to deduce the direction of Terrestrial East-West as a function of hour angle (i.e., time) for that instrument. The transit of Mercury on Nov. 15, 1999, which was recorded by three of the GONG instruments, provided an independent check on the current alignment procedures. Here we present a comparison of the alignment of GONG images as deduced from both drift scans and the Mercury transit for two GONG sites: Tucson (GONG+ camera) and Mauna Loa (GONG Classic camera). The agreement is within ~0°.01 for both cameras, however, the scatter is substantially larger for GONG Classic: ~0°.03 compared to ~0°.01 for GONG+.

  15. Absolute flux measurements for swift atoms

    NASA Technical Reports Server (NTRS)

    Fink, M.; Kohl, D. A.; Keto, J. W.; Antoniewicz, P.

    1987-01-01

    While a torsion balance in vacuum can easily measure the momentum transfer from a gas beam impinging on a surface attached to the balance, this measurement depends on the accommodation coefficients of the atoms with the surface and the distribution of the recoil. A torsion balance is described for making absolute flux measurements independent of recoil effects. The torsion balance is a conventional taut suspension wire design and the Young modulus of the wire determines the relationship between the displacement and the applied torque. A compensating magnetic field is applied to maintain zero displacement and provide critical damping. The unique feature is to couple the impinging gas beam to the torsion balance via a Wood's horn, i.e., a thin wall tube with a gradual 90 deg bend. Just as light is trapped in a Wood's horn by specular reflection from the curved surfaces, the gas beam diffuses through the tube. Instead of trapping the beam, the end of the tube is open so that the atoms exit the tube at 90 deg to their original direction. Therefore, all of the forward momentum of the gas beam is transferred to the torsion balance independent of the angle of reflection from the surfaces inside the tube.

  16. Gyrokinetic Statistical Absolute Equilibrium and Turbulence

    SciTech Connect

    Jian-Zhou Zhu and Gregory W. Hammett

    2011-01-10

    A paradigm based on the absolute equilibrium of Galerkin-truncated inviscid systems to aid in understanding turbulence [T.-D. Lee, "On some statistical properties of hydrodynamical and magnetohydrodynamical fields," Q. Appl. Math. 10, 69 (1952)] is taken to study gyrokinetic plasma turbulence: A finite set of Fourier modes of the collisionless gyrokinetic equations are kept and the statistical equilibria are calculated; possible implications for plasma turbulence in various situations are discussed. For the case of two spatial and one velocity dimension, in the calculation with discretization also of velocity v with N grid points (where N + 1 quantities are conserved, corresponding to an energy invariant and N entropy-related invariants), the negative temperature states, corresponding to the condensation of the generalized energy into the lowest modes, are found. This indicates a generic feature of inverse energy cascade. Comparisons are made with some classical results, such as those of Charney-Hasegawa-Mima in the cold-ion limit. There is a universal shape for statistical equilibrium of gyrokinetics in three spatial and two velocity dimensions with just one conserved quantity. Possible physical relevance to turbulence, such as ITG zonal flows, and to a critical balance hypothesis are also discussed.

  17. A novel scanning system using an industrial robot and the workspace measurement and positioning system

    NASA Astrophysics Data System (ADS)

    Zhao, Ziyue; Zhu, Jigui; Yang, Linghui; Lin, Jiarui

    2015-10-01

    The present scanning system consists of an industrial robot and a line-structured laser sensor which uses the industrial robot as a position instrument to guarantee the accuracy. However, the absolute accuracy of an industrial robot is relatively poor compared with the good repeatability in the manufacturing industry. This paper proposes a novel method using the workspace measurement and positioning system (wMPS) to remedy the lack of accuracy of the industrial robot. In order to guarantee the positioning accuracy of the system, the wMPS which is a laser-based measurement technology designed for large-volume metrology applications is brought in. Benefitting from the wMPS, this system can measure different cell-areas by the line-structured laser sensor and fuse the measurement data of different cell-areas by using the wMPS accurately. The system calibration which is the procedure to acquire and optimize the structure parameters of the scanning system is also stated in detail in this paper. In order to verify the feasibility of the system for scanning the large free-form surface, an experiment is designed to scan the internal surface of the door of a car-body in white. The final results show that the measurement data of the whole measuring areas have been jointed perfectly and there is no mismatch in the figure especially in the hole measuring areas. This experiment has verified the rationality of the system scheme, the correctness and effectiveness of the relevant methods.

  18. Towards Experimental Accuracy from the First Principles

    NASA Astrophysics Data System (ADS)

    Polyansky, O. L.; Lodi, L.; Tennyson, J.; Zobov, N. F.

    2013-06-01

    Producing ab initio ro-vibrational energy levels of small, gas-phase molecules with an accuracy of 0.10 cm^{-1} would constitute a significant step forward in theoretical spectroscopy and would place calculated line positions considerably closer to typical experimental accuracy. Such an accuracy has been recently achieved for the H_3^+ molecular ion for line positions up to 17 000 cm ^{-1}. However, since H_3^+ is a two-electron system, the electronic structure methods used in this study are not applicable to larger molecules. A major breakthrough was reported in ref., where an accuracy of 0.10 cm^{-1} was achieved ab initio for seven water isotopologues. Calculated vibrational and rotational energy levels up to 15 000 cm^{-1} and J=25 resulted in a standard deviation of 0.08 cm^{-1} with respect to accurate reference data. As far as line intensities are concerned, we have already achieved for water a typical accuracy of 1% which supersedes average experimental accuracy. Our results are being actively extended along two major directions. First, there are clear indications that our results for water can be improved to an accuracy of the order of 0.01 cm^{-1} by further, detailed ab initio studies. Such level of accuracy would already be competitive with experimental results in some situations. A second, major, direction of study is the extension of such a 0.1 cm^{-1} accuracy to molecules containg more electrons or more than one non-hydrogen atom, or both. As examples of such developments we will present new results for CO, HCN and H_2S, as well as preliminary results for NH_3 and CH_4. O.L. Polyansky, A. Alijah, N.F. Zobov, I.I. Mizus, R. Ovsyannikov, J. Tennyson, L. Lodi, T. Szidarovszky and A.G. Csaszar, Phil. Trans. Royal Soc. London A, {370}, 5014-5027 (2012). O.L. Polyansky, R.I. Ovsyannikov, A.A. Kyuberis, L. Lodi, J. Tennyson and N.F. Zobov, J. Phys. Chem. A, (in press). L. Lodi, J. Tennyson and O.L. Polyansky, J. Chem. Phys. {135}, 034113 (2011).

  19. Absolute nuclear material assay using count distribution (LAMBDA) space

    SciTech Connect

    Prasad, Mano K.; Snyderman, Neal J.; Rowland, Mark S.

    2015-12-01

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  20. Absolute nuclear material assay using count distribution (LAMBDA) space

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-06-05

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  1. Antifungal activity of tuberose absolute and some of its constituents.

    PubMed

    Nidiry, Eugene Sebastian J; Babu, C S Bujji

    2005-05-01

    The antifungal activity of the absolute of tuberose (Polianthes tuberosa ) and some of its constituents were evaluated against the mycelial growth of Colletotrichum gloeosporioides on potato-dextrose-agar medium. Tuberose absolute showed only mild activity at a concentration of 500 mg/L. However, three constituents present in the absolute, namely geraniol, indole and methyl anthranilate exhibited significant activity showing total inhibition of the mycelial growth at this concentration.

  2. High accuracy wavelength calibration for a scanning visible spectrometer

    SciTech Connect

    Scotti, Filippo; Bell, Ronald E.

    2010-10-15

    Spectroscopic applications for plasma velocity measurements often require wavelength accuracies {<=}0.2 A. An automated calibration, which is stable over time and environmental conditions without the need to recalibrate after each grating movement, was developed for a scanning spectrometer to achieve high wavelength accuracy over the visible spectrum. This method fits all relevant spectrometer parameters using multiple calibration spectra. With a stepping-motor controlled sine drive, an accuracy of {approx}0.25 A has been demonstrated. With the addition of a high resolution (0.075 arc sec) optical encoder on the grating stage, greater precision ({approx}0.005 A) is possible, allowing absolute velocity measurements within {approx}0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.

  3. High Accuracy Wavelength Calibration For A Scanning Visible Spectrometer

    SciTech Connect

    Filippo Scotti and Ronald Bell

    2010-07-29

    Spectroscopic applications for plasma velocity measurements often require wavelength accuracies ≤ 0.2Â. An automated calibration for a scanning spectrometer has been developed to achieve a high wavelength accuracy overr the visible spectrum, stable over time and environmental conditions, without the need to recalibrate after each grating movement. The method fits all relevant spectrometer paraameters using multiple calibration spectra. With a steping-motor controlled sine-drive, accuracies of ~0.025 Â have been demonstrated. With the addition of high resolution (0.075 aresec) optical encoder on the grading stage, greater precision (~0.005 Â) is possible, allowing absolute velocity measurements with ~0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.

  4. The Path to an Up-to-date Absolute Gravity Reference System

    NASA Astrophysics Data System (ADS)

    Wilmes, H.; Falk, R.; Wziontek, H.

    2014-12-01

    The determination of precise gravity field parameters is of great importance in a period in which earth sciences are achieving the necessary accuracy to monitor and document global change processes. This is the reason why experts from geodesy and metrology joined in a successful cooperation to make absolute gravity observations traceable to SI quantities, to improve the metrological kilogram definition and to monitor mass movements and smallest height changes for geodetic and geophysical applications. How can we determine such a gravity reference system and secure it over multiple decades? Precise knowledge of the gravity acceleration and definition of standards, models and corrections are an important prerequisite to the definition of the gravity system. Over more than three decades, the absolute gravity community cooperated successfully to obtain the gravity reference in comparisons at intervals of 4 years and to certify metrological equivalence between National Metrology Institutes. With increasing resolution of the absolute gravimeter sensors and new measurement principles it becomes obvious that such comparisons are not sufficient for all applications. Mainly for geodetic purposes it is necessary to sub-divide comparison intervals and maintain a connected network of gravity reference sites where compared absolute gravimeters operate together with superconducting gravimeters to derive a continuous gravity reference function. By means of this distributed monitoring of the gravity reference it will also be possible to relate observations of earlier absolute gravimeters to the present-day and to future instruments. It will be possible to include new sensors like atom interferometers and in future to relate the results of precise optical clocks. With co-located space geodetic sensors like GNSS, SLR and VLBI, these reference sites fulfill the conditions of a geodetic fundamental station as a component of IAG's Global Geodetic Observing System.

  5. Absolute total electron scattering cross sections for N/sub 2/ between 0. 5 and 50 eV

    SciTech Connect

    Kennerly, R.E.

    1980-06-01

    Absolute total electron scattering cross sections for N/sub 2/ from 0.5 to 50 eV have been measured with an estimated uncertainty of +- 3% using a transmission time-of-flight method previously described. The results are compared to previous experimental results and to recent calculations. The positions of the /sup 2/Pi/sub g/ resonance peaks were determined with much greater accuracy ( +- 15 meV) than in previous transmission measurements. The structure reported by Golden (1966) below the /sup 2/Pi/sub g/ resonance was clearly not present, indicating that, if real, these features are not a property of the N/sub 2/ ground vibronic state. The shape resonance predicted at 11 eV by Dill and Dehmer (1977) was not seen, perhaps because it was too weakly manifested in the total cross section. A weak broad band centered at 25 eV may be interpreted as being due to a sigma/sub u/ shape resonance as predicted by Dehmer, Siegel, Welch, and Dill.

  6. Absolute pitch among students at the Shanghai Conservatory of Music: a large-scale direct-test study.

    PubMed

    Deutsch, Diana; Li, Xiaonuo; Shen, Jing

    2013-11-01

    This paper reports a large-scale direct-test study of absolute pitch (AP) in students at the Shanghai Conservatory of Music. Overall note-naming scores were very high, with high scores correlating positively with early onset of musical training. Students who had begun training at age ≤5 yr scored 83% correct not allowing for semitone errors and 90% correct allowing for semitone errors. Performance levels were higher for white key pitches than for black key pitches. This effect was greater for orchestral performers than for pianists, indicating that it cannot be attributed to early training on the piano. Rather, accuracy in identifying notes of different names (C, C#, D, etc.) correlated with their frequency of occurrence in a large sample of music taken from the Western tonal repertoire. There was also an effect of pitch range, so that performance on tones in the two-octave range beginning on Middle C was higher than on tones in the octave below Middle C. In addition, semitone errors tended to be on the sharp side. The evidence also ran counter to the hypothesis, previously advanced by others, that the note A plays a special role in pitch identification judgments.

  7. Absolute calorimetric calibration of low energy brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Stump, Kurt E.

    the current instrument to direct further work in this field. It has been found that for sources with powers above approximately 2 muW the instrument is able to determine the source power in agreement to within less than 7% of what is expected based upon the current source strength standard. For lower power sources, the agreement is still within the uncertainty of the power measurement, but the calorimeter noise dominates. Thus, to provide absolute calibration of lower power sources additional measures must be taken. The conclusion of this thesis describes these measures and how they will improve the factors that limit the current instrument. The results of the work presented in this thesis establish the methodology of active radiometric calorimetey for the absolute calibration of radioactive sources. The method is an improvement over previous techniques in that there is no reliance upon the thermal properties of the materials used or the heat flow pathways on the source measurements. The initial work presented here will help to shape future refinements of this technique to allow lower power sources to be calibrated with high precision and high accuracy.

  8. The absolute disparity anomaly and the mechanism of relative disparities.

    PubMed

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-06-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1).

  9. The absolute disparity anomaly and the mechanism of relative disparities

    PubMed Central

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-01-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1). PMID:27248566

  10. Monitoring of absolute mirror alignment at COMPASS RICH-1 detector

    NASA Astrophysics Data System (ADS)

    Alexeev, M.; Birsa, R.; Bradamante, F.; Bressan, A.; Chiosso, M.; Ciliberti, P.; Dalla Torre, S.; Denisov, O.; Duic, V.; Ferrero, A.; Finger, M.; Finger, M.; Gayde, J. Ch.; Giorgi, M.; Gobbo, B.; Levorato, S.; Maggiora, A.; Martin, A.; Menon, G.; Panzieri, D.; Pesaro, G.; Polak, J.; Rocco, E.; Sbrizzai, G.; Schiavon, P.; Slunecka, M.; Sozzi, F.; Steiger, L.; Sulc, M.; Takekawa, S.; Tessarotto, F.

    2014-12-01

    The gaseous COMPASS RICH-1 detector uses two spherical mirror surfaces, segmented into 116 individual mirrors, to focus the Cherenkov photons onto the detector plane. Any mirror misalignment directly affects the detector resolution. The on-line Continuous Line Alignment and Monitoring (CLAM) photogrammetry-based method has been implemented to measure the alignment of individual mirrors which can be characterized by the center of curvature. The mirror wall reflects a regular grid of retroreflective strips placed inside the detector vessel. Then, the position of each mirror is determined from the image of the grid reflection. The images are collected by four cameras. Any small mirror misalignment results in changes of the grid lines' positions in the image. The accuracy limits of the CLAM method were checked by laser interferometry and are below 0.1 mrad.

  11. Recognition accuracy by experienced men and women players of basketball.

    PubMed

    Millslagle, Duane G

    2002-08-01

    This study examined 30 experienced basketball players' recognition accuracy by sex, playing position (guard, forward, and center), and situations in the game of basketball. The study used a perceptual cognitive paradigm in which subjects viewed slides of structured and unstructured game situations and accurately recognized the presence or absence of the basketball. A significant difference in recognition accuracy by sex, players' position, and structure of the game situation was found. Male players' recognition accuracy was better than the female players'. The recognition accuracy of subjects who played guard was better than that of subjects who played forward or center. The players' recognition accuracy was more accurate when observing structured plays versus unstructured plays. The conclusion of this study suggested that experienced basketball players differ in their cognitive and visual searching processes by sex and player position within the sport of basketball.

  12. Accuracy of the clinical diagnosis of recessive X-linked ichthyosis vs ichthyosis vulgaris.

    PubMed

    Cuevas-Covarrubias, S A; Kofman-Alfaro, S H; Palencia, A B; Díaz-Zagoya, J C

    1996-09-01

    The present study analyzes the accuracy of the clinical diagnosis of X-linked ichthyosis (XLI) vs ichthyosis vulgaris (IV), in a sample of Mexican patients. The study was double blind, using steroid sulfatase (STS) activity as the golden standard. Twenty male patients were included; 16 corresponded to XLI and 4 to IV. The clinical diagnosis was correct in 9 of the 16 XLI cases (56%) and in 2 of the 4 IV cases (50%). Some clinical findings in XLI, such as cryptorchidism in patients and delayed labor in their mothers, were important features for diagnosis. Statistical analysis of the results showed: among physicians (n = 2) Kappa value 0.50, specific concordance 0.40, and absolute concordance 0.75; other values were sensibility 0.56, specificity 0.50, positive predictive value 0.82, negative predictive value 0.22, accuracy 0.55, prevalence 0.80. In conclusion, the differential diagnosis of XLI and IV is very difficult, and we consider that this is not explained either by personal skills or by other conditions. It could be attributed to the similarities in skin manifestations of these two diseases. The performance of the STS assay is imperative in order to correctly diagnose the disease and offer adequate genetic counseling.

  13. High accuracy plasma density measurement using hybrid Langmuir probe and microwave interferometer method

    SciTech Connect

    Deline, C.; Gilchrist, B. E.; Dobson, C.; Jones, J. E.; Chavers, D. G.

    2007-11-15

    High spatial resolution plasma density measurements have been taken as part of an investigation into magnetic nozzle physics at the NASA/MSFC Propulsion Research Center. These measurements utilized a Langmuir triple probe scanned across the measurement chord of either of two stationary rf interferometers. By normalizing the scanned profile to the microwave interferometer line-integrated density measurement for each electrostatic probe measurement, the effect of shot-to-shot variation of the line-integrated density can be removed. In addition, by summing the voltage readings at each radial position in a transverse scan, the line density can be reconstituted, allowing the absolute density to be determined, assuming that the shape of the profile is constant from shot to shot. The spatial and temporal resolutions of this measurement technique depend on the resolutions of the scanned electrostatic probe and the interferometer. The measurement accuracy is 9%-15%, which is on the order of the accuracy of the rf interferometer. The measurement technique was compared directly with both scanning rf interferometer and standard Langmuir probe theory. The hybrid technique compares favorably with the scanning rf interferometer, and appears more accurate than probe theory alone. Additionally, our measurement technique is generally applicable even for nonaxisymmetric plasmas.

  14. High accuracy plasma density measurement using hybrid Langmuir probe and microwave interferometer method.

    PubMed

    Deline, C; Gilchrist, B E; Dobson, C; Jones, J E; Chavers, D G

    2007-11-01

    High spatial resolution plasma density measurements have been taken as part of an investigation into magnetic nozzle physics at the NASA/MSFC Propulsion Research Center. These measurements utilized a Langmuir triple probe scanned across the measurement chord of either of two stationary rf interferometers. By normalizing the scanned profile to the microwave interferometer line-integrated density measurement for each electrostatic probe measurement, the effect of shot-to-shot variation of the line-integrated density can be removed. In addition, by summing the voltage readings at each radial position in a transverse scan, the line density can be reconstituted, allowing the absolute density to be determined, assuming that the shape of the profile is constant from shot to shot. The spatial and temporal resolutions of this measurement technique depend on the resolutions of the scanned electrostatic probe and the interferometer. The measurement accuracy is 9%-15%, which is on the order of the accuracy of the rf interferometer. The measurement technique was compared directly with both scanning rf interferometer and standard Langmuir probe theory. The hybrid technique compares favorably with the scanning rf interferometer, and appears more accurate than probe theory alone. Additionally, our measurement technique is generally applicable even for nonaxisymmetric plasmas.

  15. Predicting AIDS-related events using CD4 percentage or CD4 absolute counts

    PubMed Central

    Pirzada, Yasmin; Khuder, Sadik; Donabedian, Haig

    2006-01-01

    Background The extent of immunosuppression and the probability of developing an AIDS-related complication in HIV-infected people is usually measured by the absolute number of CD4 positive T-cells. The percentage of CD4 positive cells is a more easily measured and less variable number. We analyzed sequential CD4 and CD8 numbers, percentages and ratios in 218 of our HIV infected patients to determine the most reliable predictor of an AIDS-related event. Results The CD4 percentage was an unsurpassed predictor of the occurrence of AIDS-related events when all subsets of patients are considered. The CD4 absolute count was the next most reliable, followed by the ratio of CD4/CD8 percentages. The value of CD4 percentage over the CD4 absolute count was seen even after the introduction of highly effective HIV therapy. Conclusion The CD4 percentage is unsurpassed as a parameter for predicting the onset of HIV-related diseases. The extra time and expense of measuring the CD4 absolute count may be unnecessary. PMID:16916461

  16. Absolute Plate Velocities from Seismic Anisotropy

    NASA Astrophysics Data System (ADS)

    Kreemer, Corné; Zheng, Lin; Gordon, Richard

    2015-04-01

    The orientation of seismic anisotropy inferred beneath plate interiors may provide a means to estimate the motions of the plate relative to the sub-asthenospheric mantle. Here we analyze two global sets of shear-wave splitting data, that of Kreemer [2009] and an updated and expanded data set, to estimate plate motions and to better understand the dispersion of the data, correlations in the errors, and their relation to plate speed. We also explore the effect of using geologically current plate velocities (i.e., the MORVEL set of angular velocities [DeMets et al. 2010]) compared with geodetically current plate velocities (i.e., the GSRM v1.2 angular velocities [Kreemer et al. 2014]). We demonstrate that the errors in plate motion azimuths inferred from shear-wave splitting beneath any one tectonic plate are correlated with the errors of other azimuths from the same plate. To account for these correlations, we adopt a two-tier analysis: First, find the pole of rotation and confidence limits for each plate individually. Second, solve for the best fit to these poles while constraining relative plate angular velocities to consistency with the MORVEL relative plate angular velocities. The SKS-MORVEL absolute plate angular velocities (based on the Kreemer [2009] data set) are determined from the poles from eight plates weighted proportionally to the root-mean-square velocity of each plate. SKS-MORVEL indicates that eight plates (Amur, Antarctica, Caribbean, Eurasia, Lwandle, Somalia, Sundaland, and Yangtze) have angular velocities that differ insignificantly from zero. The net rotation of the lithosphere is 0.25±0.11° Ma-1 (95% confidence limits) right-handed about 57.1°S, 68.6°E. The within-plate dispersion of seismic anisotropy for oceanic lithosphere (σ=19.2° ) differs insignificantly from that for continental lithosphere (σ=21.6° ). The between-plate dispersion, however, is significantly smaller for oceanic lithosphere (σ=7.4° ) than for continental

  17. Phylogenetic Tree Reconstruction Accuracy and Model Fit when Proportions of Variable Sites Change across the Tree

    PubMed Central

    Grievink, Liat Shavit; Penny, David; Hendy, Michael D.; Holland, Barbara R.

    2010-01-01

    Commonly used phylogenetic models assume a homogeneous process through time in all parts of the tree. However, it is known that these models can be too simplistic as they do not account for nonhomogeneous lineage-specific properties. In particular, it is now widely recognized that as constraints on sequences evolve, the proportion and positions of variable sites can vary between lineages causing heterotachy. The extent to which this model misspecification affects tree reconstruction is still unknown. Here, we evaluate the effect of changes in the proportions and positions of variable sites on model fit and tree estimation. We consider 5 current models of nucleotide sequence evolution in a Bayesian Markov chain Monte Carlo framework as well as maximum parsimony (MP). We show that for a tree with 4 lineages where 2 nonsister taxa undergo a change in the proportion of variable sites tree reconstruction under the best-fitting model, which is chosen using a relative test, often results in the wrong tree. In this case, we found that an absolute test of model fit is a better predictor of tree estimation accuracy. We also found further evidence that MP is not immune to heterotachy. In addition, we show that increased sampling of taxa that have undergone a change in proportion and positions of variable sites is critical for accurate tree reconstruction. PMID:20525636

  18. Accuracy of Digital vs. Conventional Implant Impressions

    PubMed Central

    Lee, Sang J.; Betensky, Rebecca A.; Gianneschi, Grace E.; Gallucci, German O.

    2015-01-01

    The accuracy of digital impressions greatly influences the clinical viability in implant restorations. The aim of this study is to compare the accuracy of gypsum models acquired from the conventional implant impression to digitally milled models created from direct digitalization by three-dimensional analysis. Thirty gypsum and 30 digitally milled models impressed directly from a reference model were prepared. The models were scanned by a laboratory scanner and 30 STL datasets from each group were imported to an inspection software. The datasets were aligned to the reference dataset by a repeated best fit algorithm and 10 specified contact locations of interest were measured in mean volumetric deviations. The areas were pooled by cusps, fossae, interproximal contacts, horizontal and vertical axes of implant position and angulation. The pooled areas were statistically analysed by comparing each group to the reference model to investigate the mean volumetric deviations accounting for accuracy and standard deviations for precision. Milled models from digital impressions had comparable accuracy to gypsum models from conventional impressions. However, differences in fossae and vertical displacement of the implant position from the gypsum and digitally milled models compared to the reference model, exhibited statistical significance (p<0.001, p=0.020 respectively). PMID:24720423

  19. Evaluation of the Absolute Regional Temperature Potential

    NASA Technical Reports Server (NTRS)

    Shindell, D. T.

    2012-01-01

    The Absolute Regional Temperature Potential (ARTP) is one of the few climate metrics that provides estimates of impacts at a sub-global scale. The ARTP presented here gives the time-dependent temperature response in four latitude bands (90-28degS, 28degS-28degN, 28-60degN and 60-90degN) as a function of emissions based on the forcing in those bands caused by the emissions. It is based on a large set of simulations performed with a single atmosphere-ocean climate model to derive regional forcing/response relationships. Here I evaluate the robustness of those relationships using the forcing/response portion of the ARTP to estimate regional temperature responses to the historic aerosol forcing in three independent climate models. These ARTP results are in good accord with the actual responses in those models. Nearly all ARTP estimates fall within +/-20%of the actual responses, though there are some exceptions for 90-28degS and the Arctic, and in the latter the ARTP may vary with forcing agent. However, for the tropics and the Northern Hemisphere mid-latitudes in particular, the +/-20% range appears to be roughly consistent with the 95% confidence interval. Land areas within these two bands respond 39-45% and 9-39% more than the latitude band as a whole. The ARTP, presented here in a slightly revised form, thus appears to provide a relatively robust estimate for the responses of large-scale latitude bands and land areas within those bands to inhomogeneous radiative forcing and thus potentially to emissions as well. Hence this metric could allow rapid evaluation of the effects of emissions policies at a finer scale than global metrics without requiring use of a full climate model.

  20. Absolute Radiometric Calibration of KOMPSAT-3A

    NASA Astrophysics Data System (ADS)

    Ahn, H. Y.; Shin, D. Y.; Kim, J. S.; Seo, D. C.; Choi, C. U.

    2016-06-01

    This paper presents a vicarious radiometric calibration of the Korea Multi-Purpose Satellite-3A (KOMPSAT-3A) performed by the Korea Aerospace Research Institute (KARI) and the Pukyong National University Remote Sensing Group (PKNU RSG) in 2015.The primary stages of this study are summarized as follows: (1) A field campaign to determine radiometric calibrated target fields was undertaken in Mongolia and South Korea. Surface reflectance data obtained in the campaign were input to a radiative transfer code that predicted at-sensor radiance. Through this process, equations and parameters were derived for the KOMPSAT-3A sensor to enable the conversion of calibrated DN to physical units, such as at-sensor radiance or TOA reflectance. (2) To validate the absolute calibration coefficients for the KOMPSAT-3A sensor, we performed a radiometric validation with a comparison of KOMPSAT-3A and Landsat-8 TOA reflectance using one of the six PICS (Libya 4). Correlations between top-of-atmosphere (TOA) radiances and the spectral band responses of the KOMPSAT-3A sensors at the Zuunmod, Mongolia and Goheung, South Korea sites were significant for multispectral bands. The average difference in TOA reflectance between KOMPSAT-3A and Landsat-8 image over the Libya 4, Libya site in the red-green-blue (RGB) region was under 3%, whereas in the NIR band, the TOA reflectance of KOMPSAT-3A was lower than the that of Landsat-8 due to the difference in the band passes of two sensors. The KOMPSAT-3Aensor includes a band pass near 940 nm that can be strongly absorbed by water vapor and therefore displayed low reflectance. Toovercome this, we need to undertake a detailed analysis using rescale methods, such as the spectral bandwidth adjustment factor.

  1. Absolute determination of local tropospheric OH concentrations

    NASA Technical Reports Server (NTRS)

    Armerding, Wolfgang; Comes, Franz-Josef

    1994-01-01

    Long path absorption (LPA) according to Lambert Beer's law is a method to determine absolute concentrations of trace gases such as tropospheric OH. We have developed a LPA instrument which is based on a rapid tuning of the light source which is a frequency doubled dye laser. The laser is tuned across two or three OH absorption features around 308 nm with a scanning speed of 0.07 cm(exp -1)/microsecond and a repetition rate of 1.3 kHz. This high scanning speed greatly reduces the fluctuation of the light intensity caused by the atmosphere. To obtain the required high sensitivity the laser output power is additionally made constant and stabilized by an electro-optical modulator. The present sensitivity is of the order of a few times 10(exp 5) OH per cm(exp 3) for an acquisition time of a minute and an absorption path length of only 1200 meters so that a folding of the optical path in a multireflection cell was possible leading to a lateral dimension of the cell of a few meters. This allows local measurements to be made. Tropospheric measurements have been carried out in 1991 resulting in the determination of OH diurnal variation at specific days in late summer. Comparison with model calculations have been made. Interferences are mainly due to SO2 absorption. The problem of OH self generation in the multireflection cell is of minor extent. This could be shown by using different experimental methods. The minimum-maximum signal to noise ratio is about 8 x 10(exp -4) for a single scan. Due to the small size of the absorption cell the realization of an open air laboratory is possible in which by use of an additional UV light source or by additional fluxes of trace gases the chemistry can be changed under controlled conditions allowing kinetic studies of tropospheric photochemistry to be made in open air.

  2. Improving absolute gravity estimates by the L p -norm approximation of the ballistic trajectory

    NASA Astrophysics Data System (ADS)

    Nagornyi, V. D.; Svitlov, S.; Araya, A.

    2016-04-01

    Iteratively re-weighted least squares (IRLS) were used to simulate the L p -norm approximation of the ballistic trajectory in absolute gravimeters. Two iterations of the IRLS delivered sufficient accuracy of the approximation without a significant bias. The simulations were performed on different samplings and perturbations of the trajectory. For the platykurtic distributions of the perturbations, the L p -approximation with 3  <  p  <  4 was found to yield several times more precise gravity estimates compared to the standard least-squares. The simulation results were confirmed by processing real gravity observations performed at the excessive noise conditions.

  3. Characterizing flow in oil reservoir rock using SPH: absolute permeability

    NASA Astrophysics Data System (ADS)

    Holmes, David W.; Williams, John R.; Tilke, Peter; Leonardi, Christopher R.

    2016-04-01

    In this paper, a three-dimensional smooth particle hydrodynamics (SPH) simulator for modeling grain scale fluid flow in porous rock is presented. The versatility of the SPH method has driven its use in increasingly complex areas of flow analysis, including flows related to permeable rock for both groundwater and petroleum reservoir research. While previous approaches to such problems using SPH have involved the use of idealized pore geometries (cylinder/sphere packs etc), in this paper we detail the characterization of flow in models with geometries taken from 3D X-ray microtomographic imaging of actual porous rock; specifically 25.12 % porosity dolomite. This particular rock type has been well characterized experimentally and described in the literature, thus providing a practical `real world' means of verification of SPH that will be key to its acceptance by industry as a viable alternative to traditional reservoir modeling tools. The true advantages of SPH are realized when adding the complexity of multiple fluid phases, however, the accuracy of SPH for single phase flow is, as yet, under developed in the literature and will be the primary focus of this paper. Flow in reservoir rock will typically occur in the range of low Reynolds numbers, making the enforcement of no-slip boundary conditions an important factor in simulation. To this end, we detail the development of a new, robust, and numerically efficient method for implementing no-slip boundary conditions in SPH that can handle the degree of complexity of boundary surfaces, characteristic of an actual permeable rock sample. A study of the effect of particle density is carried out and simulation results for absolute permeability are presented and compared to those from experimentation showing good agreement and validating the method for such applications.

  4. Absolute homogeneity test of Kelantan catchment precipitation series

    NASA Astrophysics Data System (ADS)

    Ros, Faizah Che; Tosaka, Hiroyuki; Sasaki, Kenji; Sidek, Lariyah Mohd; Basri, Hidayah

    2015-05-01

    Along the Kelantan River in north east of Malaysia Peninsular, there are several areas often damaged by flood during north-east monsoon season every year. It is vital to predict the expected behavior of precipitation and river runoff for reducing flood damages of the area under rapid urbanization and future planning. Nevertheless, the accuracy and reliability of any hydrological and climate studies vary based on the quality of the data used. The factors causing variations on these data are the method of gauging and data collection, stations environment, station relocation and the reliability of the measurement tool affect the homogenous precipitation records. Hence in this study, homogeneity of long precipitation data series is checked via the absolute homogeneity test consisting of four methods namely Pettitt test, standard normal homogeneity test (SNHT), Buishand range test and Von Neumann ratio test. For homogeneity test, the annual rainfall amount from the daily precipitation records at stations located in Kelantan operated by Department of Irrigation and Drainage Malaysia were considered in this study. The missing values were completed using the correlation and regression and inverse distance method. The data network consists of 103 precipitation gauging stations where 31 points are inactive, 6 gauging stations had missing precipitation values more than five years in a row and 16 stations have records less than twenty years. So total of 50 stations gauging stations were evaluated in this analysis. With the application of the mentioned methods and further graphical analysis, inhomogeneity was detected at 4 stations and 46 stations are found to be homogeneous.

  5. In-flight quality and accuracy of attitude measurements from the CHAMP advanced stellar compass

    NASA Astrophysics Data System (ADS)

    Jørgensen, Peter S.; Jørgensen, John L.; Denver, Troelz; Betto, Maurizio

    2005-01-01

    The German geo-observations satellite CHAMP carries highly accurate vector instruments. The orientation of these relative to the inertial reference frame is obtained using star trackers. These advanced stellar compasses (ASC) are fully autonomous units, which provide, in real time, the absolute attitude with accuracy in the arc second range. In order to investigate the in-flight accuracy of the ASC, the terminology to characterize noise and biases is introduced. Relative instrument accuracy (RIA) and absolute instrument accuracy (AIA) can in principle be determined in-flight. However problems with modeling external noise sources often arise. The special CHAMP configuration with two star tracker cameras mounted fixed together provides an excellent opportunity to determine the AIA in-flight using the inter boresight angle.

  6. Parenting and Adolescents' Accuracy in Perceiving Parental Values.

    ERIC Educational Resources Information Center

    Knafo, Ariel; Schwartz, Shalom H.

    2003-01-01

    Examined potential predictors of Israeli adolescents' accuracy in perceiving parental values. Found that accuracy in perceiving parents' overall value system correlated positively with parents' actual and perceived value agreement and perceived parental warmth and responsiveness, but negatively with perceived value conflict, indifferent parenting,…

  7. Mid-infrared absolute spectral responsivity scale based on an absolute cryogenic radiometer and an optical parametric oscillator laser

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Shi, Xueshun; Chen, Haidong; Liu, Yulong; Liu, Changming; Chen, Kunfeng; Li, Ligong; Gan, Haiyong; Ma, Chong

    2016-06-01

    We are reporting on a laser-based absolute spectral responsivity scale in the mid-infrared spectral range. By using a mid-infrared tunable optical parametric oscillator as the laser source, the absolute responsivity scale has been established by calibrating thin-film thermopile detectors against an absolute cryogenic radiometer. The thin-film thermopile detectors can be then used as transfer standard detectors. The extended uncertainty of the absolute spectral responsivity measurement has been analyzed to be 0.58%–0.68% (k  =  2).

  8. Mid-infrared absolute spectral responsivity scale based on an absolute cryogenic radiometer and an optical parametric oscillator laser

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Shi, Xueshun; Chen, Haidong; Liu, Yulong; Liu, Changming; Chen, Kunfeng; Li, Ligong; Gan, Haiyong; Ma, Chong

    2016-06-01

    We are reporting on a laser-based absolute spectral responsivity scale in the mid-infrared spectral range. By using a mid-infrared tunable optical parametric oscillator as the laser source, the absolute responsivity scale has been established by calibrating thin-film thermopile detectors against an absolute cryogenic radiometer. The thin-film thermopile detectors can be then used as transfer standard detectors. The extended uncertainty of the absolute spectral responsivity measurement has been analyzed to be 0.58%-0.68% (k  =  2).

  9. The study of the nonlinear correction of the FMCW absolute distance measurement using frequency-sampling and precision analysis

    NASA Astrophysics Data System (ADS)

    Lu, Cheng; Gan, Yu; Chen, Fengdong; Liu, Bingguo; Zhuang, Zhitao; Xu, Xinke; Liu, Guodong

    2014-12-01

    This article uses the external cavity laser to realize FMCW high precision absolute distance measurement, as the external cavity laser owns the advantage of large tuning range of frequency. Firstly, aim at the problem of nonlinear tuning of the external cavity laser, a study of method of frequency-sampling has been shown. Secondly, in this article the mathematical model of the absolute dis tance measurement system has been established, and the sources of the errors of the FMCW absolute distance measurement has been analyzed, and the accuracy model has been established. Finally, a ball which is put at a distance about 3 meters is measured, and the random error is 0.3479μm, the standard uncertainty of measurement system is 0.3479μm+3.141Rppm.

  10. Navigation in Orthognathic Surgery: 3D Accuracy.

    PubMed

    Badiali, Giovanni; Roncari, Andrea; Bianchi, Alberto; Taddei, Fulvia; Marchetti, Claudio; Schileo, Enrico

    2015-10-01

    This article aims to determine the absolute accuracy of maxillary repositioning during orthognathic surgery according to simulation-guided navigation, that is, the combination of navigation and three-dimensional (3D) virtual surgery. We retrospectively studied 15 patients treated for asymmetric dentofacial deformities at the Oral and Maxillofacial Surgery Unit of the S.Orsola-Malpighi University Hospital in Bologna, Italy, from January 2010 to January 2012. Patients were scanned with a cone-beam computed tomography before and after surgery. The virtual surgical simulation was realized with a dedicated software and loaded on a navigation system to improve intraoperative reproducibility of the preoperative planning. We analyzed the outcome following two protocols: (1) planning versus postoperative 3D surface analysis; (2) planning versus postoperative point-based analysis. For 3D surface comparison, the mean Hausdorff distance was measured, and median among cases was 0.99 mm. Median reproducibility < 1 mm was 61.88% and median reproducibility < 2 mm was 85.46%. For the point-based analysis, with sign, the median distance was 0.75 mm in the frontal axis, -0.05 mm in the caudal-cranial axis, -0.35 mm in the lateral axis. In absolute value, the median distance was 1.19 mm in the frontal axis, 0.59 mm in the caudal-cranial axis, and 1.02 mm in the lateral axis. We suggest that simulation-guided navigation makes accurate postoperative outcomes possible for maxillary repositioning in orthognathic surgery, if compared with the surgical computer-designed project realized with a dedicated software, particularly for the vertical dimension, which is the most challenging to manage.

  11. Presenting a high accuracy Theta-Phi-style fiber-positioner prototype with a 15-mm pitch

    NASA Astrophysics Data System (ADS)

    Haeuser, Marco; Lang-Bardl, Florian; Richter, Josef; Hess, Hans-Joachim; Degwert, Adrian; Karasz, Adolf; Kosyra, Ralf; Hopp, Ulrich; Bender, Ralf

    2014-07-01

    We present a Θ - Φ-style fiber-positioner prototype, which will be controlled via the EMI-robust CAN-Bus. Our positioner points without iterations or a metrology system. Due to the overlapping patrol disc of 17.3 mm diameter, we reach a filling factor of 100 %. The positioners diameter is 14.6 mm, containing the control electronics on a contemporary PCB of 13.5 mm width. While moving, the power consumption does not lead to a significant rise in temperature. Given a mechanical reference point measured by stall detection, the absolute accuracy is 27 μm (1σ = 14 µm) and pointings are repeatable with 7 μm (1σ = 4 μm). Better positioning may be reachable with upcoming calibration.

  12. Landsat classification accuracy assessment procedures

    USGS Publications Warehouse

    Mead, R. R.; Szajgin, John

    1982-01-01

    A working conference was held in Sioux Falls, South Dakota, 12-14 November, 1980 dealing with Landsat classification Accuracy Assessment Procedures. Thirteen formal presentations were made on three general topics: (1) sampling procedures, (2) statistical analysis techniques, and (3) examples of projects which included accuracy assessment and the associated costs, logistical problems, and value of the accuracy data to the remote sensing specialist and the resource manager. Nearly twenty conference attendees participated in two discussion sessions addressing various issues associated with accuracy assessment. This paper presents an account of the accomplishments of the conference.

  13. Novalis' Poetic Uncertainty: A "Bildung" with the Absolute

    ERIC Educational Resources Information Center

    Mika, Carl

    2016-01-01

    Novalis, the Early German Romantic poet and philosopher, had at the core of his work a mysterious depiction of the "absolute." The absolute is Novalis' name for a substance that defies precise knowledge yet calls for a tentative and sensitive speculation. How one asserts a truth, represents an object, and sets about encountering things…

  14. Absolute Pitch in Infant Auditory Learning: Evidence for Developmental Reorganization.

    ERIC Educational Resources Information Center

    Saffran, Jenny R.; Griepentrog, Gregory J.

    2001-01-01

    Two experiments examined 8-month-olds' use of absolute and relative pitch cues in a tone-sequence statistical learning task. Results suggest that, given unsegmented stimuli that do not conform to rules of musical composition, infants are more likely to track patterns of absolute pitches than of relative pitches. A third experiment found that adult…

  15. Supplementary and Enrichment Series: Absolute Value. Teachers' Commentary. SP-25.

    ERIC Educational Resources Information Center

    Bridgess, M. Philbrick, Ed.

    This is one in a series of manuals for teachers using SMSG high school supplementary materials. The pamphlet includes commentaries on the sections of the student's booklet, answers to the exercises, and sample test questions. Topics covered include addition and multiplication in terms of absolute value, graphs of absolute value in the Cartesian…

  16. Supplementary and Enrichment Series: Absolute Value. SP-24.

    ERIC Educational Resources Information Center

    Bridgess, M. Philbrick, Ed.

    This is one in a series of SMSG supplementary and enrichment pamphlets for high school students. This series is designed to make material for the study of topics of special interest to students readily accessible in classroom quantity. Topics covered include absolute value, addition and multiplication in terms of absolute value, graphs of absolute…

  17. Absolute dimensions of unevolved O type close binaries

    SciTech Connect

    Doom, C.; de Loore, C.

    1984-03-15

    A method is presented to derive the absolute dimensions of early-type detached binaries by combining the observed parameters with results of evolutionary computations. The method is used to obtain the absolute dimensions of nine close binaries. We find that most systems have an initial masss ratio near 1.

  18. Absolute Humidity and the Seasonality of Influenza (Invited)

    NASA Astrophysics Data System (ADS)

    Shaman, J. L.; Pitzer, V.; Viboud, C.; Grenfell, B.; Goldstein, E.; Lipsitch, M.

    2010-12-01

    Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent re-analysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here we show that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions. In addition, we show that variations of the basic and effective reproductive numbers for influenza, caused by seasonal changes in absolute humidity, are consistent with the general timing of pandemic influenza outbreaks observed for 2009 A/H1N1 in temperate regions. Indeed, absolute humidity conditions correctly identify the region of the United States vulnerable to a third, wintertime wave of pandemic influenza. These findings suggest that the timing of pandemic influenza outbreaks is controlled by a combination of absolute humidity conditions, levels of susceptibility and changes in population mixing and contact rates.

  19. Determination of Absolute Zero Using a Computer-Based Laboratory

    ERIC Educational Resources Information Center

    Amrani, D.

    2007-01-01

    We present a simple computer-based laboratory experiment for evaluating absolute zero in degrees Celsius, which can be performed in college and undergraduate physical sciences laboratory courses. With a computer, absolute zero apparatus can help demonstrators or students to observe the relationship between temperature and pressure and use…

  20. Optimal Centroid Position Estimation

    SciTech Connect

    Candy, J V; McClay, W A; Awwal, A S; Ferguson, S W

    2004-07-23

    The alignment of high energy laser beams for potential fusion experiments demand high precision and accuracy by the underlying positioning algorithms. This paper discusses the feasibility of employing online optimal position estimators in the form of model-based processors to achieve the desired results. Here we discuss the modeling, development, implementation and processing of model-based processors applied to both simulated and actual beam line data.