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Sample records for high accuracy measurements

  1. High accuracy radiation efficiency measurement techniques

    NASA Technical Reports Server (NTRS)

    Kozakoff, D. J.; Schuchardt, J. M.

    1981-01-01

    The relatively large antenna subarrays (tens of meters) to be used in the Solar Power Satellite, and the desire to accurately quantify antenna performance, dictate the requirement for specialized measurement techniques. The error contributors associated with both far-field and near-field antenna measurement concepts were quantified. As a result, instrumentation configurations with measurement accuracy potential were identified. In every case, advances in the state of the art of associated electronics were found to be required. Relative cost trade-offs between a candidate far-field elevated antenna range and near-field facility were also performed.

  2. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units

    PubMed Central

    Cai, Qingzhong; Yang, Gongliu; Song, Ningfang; Liu, Yiliang

    2016-01-01

    An inertial navigation system (INS) has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10−6°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs) using common turntables, has a great application potential in future atomic gyro INSs. PMID:27338408

  3. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units.

    PubMed

    Cai, Qingzhong; Yang, Gongliu; Song, Ningfang; Liu, Yiliang

    2016-01-01

    An inertial navigation system (INS) has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10(-6)°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs) using common turntables, has a great application potential in future atomic gyro INSs. PMID:27338408

  4. High-accuracy measurements of the normal specular reflectance

    SciTech Connect

    Voarino, Philippe; Piombini, Herve; Sabary, Frederic; Marteau, Daniel; Dubard, Jimmy; Hameury, Jacques; Filtz, Jean Remy

    2008-05-01

    The French Laser Megajoule (LMJ) is designed and constructed by the French Commissariata l'Energie Atomique (CEA). Its amplifying section needs highly reflective multilayer mirrors for the flash lamps. To monitor and improve the coating process, the reflectors have to be characterized to high accuracy. The described spectrophotometer is designed to measure normal specular reflectance with high repeatability by using a small spot size of 100 {mu}m. Results are compared with ellipsometric measurements. The instrument can also perform spatial characterization to detect coating nonuniformity.

  5. High Accuracy Temperature Measurements Using RTDs with Current Loop Conditioning

    NASA Technical Reports Server (NTRS)

    Hill, Gerald M.

    1997-01-01

    To measure temperatures with a greater degree of accuracy than is possible with thermocouples, RTDs (Resistive Temperature Detectors) are typically used. Calibration standards use specialized high precision RTD probes with accuracies approaching 0.001 F. These are extremely delicate devices, and far too costly to be used in test facility instrumentation. Less costly sensors which are designed for aeronautical wind tunnel testing are available and can be readily adapted to probes, rakes, and test rigs. With proper signal conditioning of the sensor, temperature accuracies of 0.1 F is obtainable. For reasons that will be explored in this paper, the Anderson current loop is the preferred method used for signal conditioning. This scheme has been used in NASA Lewis Research Center's 9 x 15 Low Speed Wind Tunnel, and is detailed.

  6. CHARMS: The Cryogenic, High-Accuracy Refraction Measuring System

    NASA Technical Reports Server (NTRS)

    Frey, Bradley; Leviton, Douglas

    2004-01-01

    The success of numerous upcoming NASA infrared (IR) missions will rely critically on accurate knowledge of the IR refractive indices of their constituent optical components at design operating temperatures. To satisfy the demand for such data, we have built a Cryogenic, High-Accuracy Refraction Measuring System (CHARMS), which, for typical 1R materials. can measure the index of refraction accurate to (+ or -) 5 x 10sup -3 . This versatile, one-of-a-kind facility can also measure refractive index over a wide range of wavelengths, from 0.105 um in the far-ultraviolet to 6 um in the IR, and over a wide range of temperatures, from 10 K to 100 degrees C, all with comparable accuracies. We first summarize the technical challenges we faced and engineering solutions we developed during the construction of CHARMS. Next we present our "first light," index of refraction data for fused silica and compare our data to previously published results.

  7. Kodak DCS200: a camera for high-accuracy measurements?

    NASA Astrophysics Data System (ADS)

    Gruen, Armin; Maas, Hans-Gerd; Keller, Andrea

    1995-09-01

    The digital high-resolution stillvideo camera Kodak DCS200 has reached a high degree of popularity among photogrammetrists within a very short time. Consisting of a mirror reflex camera, a high resolution CCD sensor, A/D conversion, power supply, and data storage capacity for 50 images, it can basically be considered a comfortable, autonomous device for digital image data acquisition, especially for industrial applications and for architectural photogrammetry. First tests of the camera showed a high precision potential: 1/20-1/30 pixel in image space could be achieved in several applications, and with large self-calibrating networks relative precisions of 1:100,000 and better have been reported. To be able to make more detailed statements on the accuracy potential of the camera, a thorough accuracy test was performed at ETH Zurich by taking 150 images of a 186 target 3D testfield. Although the precision estimates of this large block were exceptionally good, strong systematic object deformations were found in comparison with theodolite-measured reference coordinates of the testfield points. The reasons for these deformations are most probably temporal instabilities of some camera parameters, which could make the use of this camera very problematic for high accuracy applications. It is argued that these instabilities are caused by the weak fixture of the CCD-chip to the camera body. In this context it is often overlooked that this camera was not developed for precise measurement applications but rather for professional photographers.

  8. Method for high-accuracy multiplicity-correlation measurements

    NASA Astrophysics Data System (ADS)

    Gulbrandsen, K.; Søgaard, C.

    2016-04-01

    Multiplicity-correlation measurements provide insight into the dynamics of high-energy collisions. Models describing these collisions need these correlation measurements to tune the strengths of the underlying QCD processes which influence all observables. Detectors, however, often possess limited coverage or reduced efficiency that influence correlation measurements in obscure ways. In this paper, the effects of nonuniform detection acceptance and efficiency on the measurement of multiplicity correlations between two distinct detector regions (termed forward-backward correlations) are derived. An analysis method with such effects built in is developed and subsequently verified using different event generators. The resulting method accounts for acceptance and efficiency in a model-independent manner with high accuracy, thereby shedding light on the relative contributions of the underlying processes to particle production.

  9. A High-accuracy Micro-deformation Measurement Method

    NASA Astrophysics Data System (ADS)

    Jiang, Li

    2016-07-01

    The requirement for ever-increasing-resolution space cameras drives focal length and diameter of optical lenses be increasing. High-frequency vibration in the process of launching and complex environmental conditions of the outer space generate micro deformation in components of space cameras. As a result, images from the space cameras are blurred. Therefore, it is necessary to measure the micro deformations in components of space cameras in various experiment conditions. This paper presents a high-accuracy micro deformation measurement method. The method is implemented as follows: (1) fix Tungsten-steel balls onto a space camera being measured and measure the coordinate for each ball under the standard condition; (2) simulate high-frequency vibrations and environmental conditions like the outer space to measure coordinates for each ball under each combination of test conditions; and (3) compute the deviation of a coordinate of a ball under a test condition combination from the coordinate of the ball under the standard condition and the deviation is the micro deformation of the space camera component associated with the ball. This method was applied to micro deformation measurement for space cameras of different models. Measurement data for these space cameras validated the proposed method.

  10. Creation of Data Pattern for High Accuracy Flying Height Measurement

    NASA Astrophysics Data System (ADS)

    Tang, Yawshing; Lee, Sung-Chang; Suk, Mike

    A common technique for measuring flying height is using the ratio of the 1st and the 3rd harmonic of a periodic data pattern. Since the 3rd harmonic is typically smaller than the 1st, and the recording channel usually rolls off at higher harmonics, the magnitude of the 3rd harmonic dominates the signal to noise ratio of the measured flying height. Therefore it is desirable to create a data pattern that has a large 3rd harmonic component for flying height measurement. This paper describes a method to create data patterns with a high frequency component larger than the 1st harmonic. The method multiplies a high frequency signal to a basic periodic signal to create a high frequency component and a low frequency component. The high frequency signal may be the 3rd harmonic and can be larger than the low frequency one. In addition, newly created data pattern was applied to real hard disk drive, and the accuracy of measured flying height was demonstrated in comparison with measured flying height based on conventional data pattern.

  11. Measurement system with high accuracy for laser beam quality.

    PubMed

    Ke, Yi; Zeng, Ciling; Xie, Peiyuan; Jiang, Qingshan; Liang, Ke; Yang, Zhenyu; Zhao, Ming

    2015-05-20

    Presently, most of the laser beam quality measurement system collimates the optical path manually with low efficiency and low repeatability. To solve these problems, this paper proposed a new collimated method to improve the reliability and accuracy of the measurement results. The system accuracy controlled the position of the mirror to change laser beam propagation direction, which can realize the beam perpendicularly incident to the photosurface of camera. The experiment results show that the proposed system has good repeatability and the measuring deviation of M2 factor is less than 0.6%. PMID:26192526

  12. Global High-Accuracy Intercomparison of Slope Measuring Instruments

    SciTech Connect

    Siewert, Frank; Lammert, Heiner; Zeschke, Thomas; Assoufid, Lahsen; Cocco, Daniele; Sostero, Giovani; Hignette, Olivier; Rommeveaux, Amparo; Irick, Steve; McKinney, Wayne; Yashchuk, Valeriy; Ohashi, Haruhiko; Qian, Shinan; Takacs, Peter; Rah, Seungyu; Yamauchi, Kazuto

    2007-01-19

    The upcoming generation of high accuracy synchrotron radiation (SR) optics will be characterized by a slope deviation from ideal shape in the range of some 0.05{mu}rad rms at a sampling interval of about 1mm. To certify and improve the measurement capabilities of metrology tools to inspect these stringent specifications, an essential step is a worldwide intercomparison of these measurements based on a set of transfer standards. It is the aim of these cross measurements to verify the ''absolute'' correctness and comparability of the measurement results obtained by the cooperating partners when measuring the topography of specific reference optics (ROs) using their latest metrology tools and methods. Organized by members of the SR-optics community, new national and international cross measurement comparisons of typical synchrotron radiation mirrors have been realized during the last few years: A round robin test by the European COST-program (BESSY, Elettra, ESRF, Soleil) during the years 2004-2005 and a similar cooperation realized by the APS, ESRF and Spring-8 have proceeded. The first results of both projects were presented at the ''Optics and Photonics'' conference in San Diego in August 2005. This work build upon earlier work. The participants of both groups and representatives of other SR-laboratories agreed to start a global cooperation bringing together the two round-robin projects and open these activities to other partners from the SR-community, optical manufacturers and other interested parties. This initiative is intended to start an extensive comparison of various measurement principles and tools and will help to push the frontiers in metrology, and hence production, to a precision well below the current state-of-the-art limit of 0.5{mu}rad rms for slope errors.

  13. Accuracy assessment of high-rate GPS measurements for seismology

    NASA Astrophysics Data System (ADS)

    Elosegui, P.; Davis, J. L.; Ekström, G.

    2007-12-01

    Analysis of GPS measurements with a controlled laboratory system, built to simulate the ground motions caused by tectonic earthquakes and other transient geophysical signals such as glacial earthquakes, enables us to assess the technique of high-rate GPS. The root-mean-square (rms) position error of this system when undergoing realistic simulated seismic motions is 0.05~mm, with maximum position errors of 0.1~mm, thus providing "ground truth" GPS displacements. We have acquired an extensive set of high-rate GPS measurements while inducing seismic motions on a GPS antenna mounted on this system with a temporal spectrum similar to real seismic events. We found that, for a particular 15-min-long test event, the rms error of the 1-Hz GPS position estimates was 2.5~mm, with maximum position errors of 10~mm, and the error spectrum of the GPS estimates was approximately flicker noise. These results may however represent a best-case scenario since they were obtained over a short (~10~m) baseline, thereby greatly mitigating baseline-dependent errors, and when the number and distribution of satellites on the sky was good. For example, we have determined that the rms error can increase by a factor of 2--3 as the GPS constellation changes throughout the day, with an average value of 3.5~mm for eight identical, hourly-spaced, consecutive test events. The rms error also increases with increasing baseline, as one would expect, with an average rms error for a ~1400~km baseline of 9~mm. We will present an assessment of the accuracy of high-rate GPS based on these measurements, discuss the implications of this study for seismology, and describe new applications in glaciology.

  14. Phase error compensation methods for high-accuracy profile measurement

    NASA Astrophysics Data System (ADS)

    Cai, Zewei; Liu, Xiaoli; Peng, Xiang; Zhang, Zonghua; Jiang, Hao; Yin, Yongkai; Huang, Shujun

    2016-04-01

    In a phase-shifting algorithm-based fringe projection profilometry, the nonlinear intensity response, called the gamma effect, of the projector-camera setup is a major source of error in phase retrieval. This paper proposes two novel, accurate approaches to realize both active and passive phase error compensation based on a universal phase error model which is suitable for a arbitrary phase-shifting step. The experimental results on phase error compensation and profile measurement of standard components verified the validity and accuracy of the two proposed approaches which are robust when faced with changeable measurement conditions.

  15. High accuracy measurement of optical atomic clock polarizability

    NASA Astrophysics Data System (ADS)

    Sherman, Jeff; Lemke, Nathan; Hinkley, Nathan; Pizzocaro, Marco; Fox, Richard; Ludlow, Andrew; Oates, Chris

    2012-06-01

    The differential static polarizability of ytterbium optical clock states αclock≡α(^3 0) - α(^1 0) is known theoretically to ˜10%. We report an experimental value of this polarizability, αclock= 36.2612(7) kHz (kV/cm)-2 at 20 parts-per-million (ppm) accuracy [1]. Ultracold ^171Yb atoms held in an optical lattice at the ac-Stark balancing ``magic'' wavelength (759 nm) are surrounded by rigidly spaced transparent conductive planar electrodes. An ultrastable laser (578 nm) is locked to the ^1 0<->^3 0 transition in an interleaved fashion for three electrode conditions: voltage applied, reversed, and grounded. These integrated error signals yield the quadratic Stark shift and a measure of stray fields. The electrode spacing is measured interferometrically in situ. The applied electric field at the site of the atoms deviates at the few ppm level from an infinite-planar model. When last evaluated, the ytterbium optical clock frequency uncertainty was dominated by that of the blackbody Stark shift. We show how this measurement reduces this uncertainty contribution an order of magnitude to a fractional level of 3x10-17.[4pt] [1] J.A. Sherman et al., arXiv:1112.2766 (2011).

  16. Edge technique lidar for high accuracy, high spatial resolution wind measurement in the Planetary Boundary Layer

    NASA Technical Reports Server (NTRS)

    Korb, C. L.; Gentry, Bruce M.

    1995-01-01

    The goal of the Army Research Office (ARO) Geosciences Program is to measure the three dimensional wind field in the planetary boundary layer (PBL) over a measurement volume with a 50 meter spatial resolution and with measurement accuracies of the order of 20 cm/sec. The objective of this work is to develop and evaluate a high vertical resolution lidar experiment using the edge technique for high accuracy measurement of the atmospheric wind field to meet the ARO requirements. This experiment allows the powerful capabilities of the edge technique to be quantitatively evaluated. In the edge technique, a laser is located on the steep slope of a high resolution spectral filter. This produces large changes in measured signal for small Doppler shifts. A differential frequency technique renders the Doppler shift measurement insensitive to both laser and filter frequency jitter and drift. The measurement is also relatively insensitive to the laser spectral width for widths less than the width of the edge filter. Thus, the goal is to develop a system which will yield a substantial improvement in the state of the art of wind profile measurement in terms of both vertical resolution and accuracy and which will provide a unique capability for atmospheric wind studies.

  17. Ultrasensitive, High Accuracy Measurements of Trace Gas Species

    NASA Astrophysics Data System (ADS)

    Long, David A.; Fleisher, Adam J.; Plusquellic, David F.; Hodges, Joseph

    2015-06-01

    Our laboratory seeks to apply novel cavity-enhanced spectroscopic techniques to present problems in atmospheric and physical chemistry. Primarily we use cavity ring-down spectroscopy in which the passive decay of optical power within a Fabry-Pérot resonator is utilized to extract an absorption signal. With this technique we have demonstrated quantum (shot) noise limited sensitivities in both the near-infrared and mid-infrared spectral regions. Both commercial and home-built optical frequency combs are employed either to serve as absolute frequency references for molecular spectra or in a multiheterodyne approach for multiplexed sensing. I will discuss this novel instrumentation as well as measurements we have made of atmospherically relevant species such as CO2, H2O, O2, CH4, and CO with implications for in situ and remote (i.e. satellite-based) sensing. I will conclude by discussing future directions and plans for challenging measurements in the mid-infrared.

  18. Tailoring Inlet Flow to Enable High Accuracy Compressor Performance Measurements

    NASA Astrophysics Data System (ADS)

    Brossman, John R.; Smith, Natalie R.; Talalayev, Anton; Key, Nicole L.

    2011-12-01

    To accomplish the research goals of capturing the effects of blade row interactions on compressor performance, small changes in performance must be measurable. This also requires axi-symmetric flow so that measuring one passage accurately captures the phenomena occurring in all passages. Thus, uniform inlet flow is a necessity. The original front-driven compressor had non-uniform temperature at the inlet. Additional challenges in controlling shaft speed to within tight tolerances were associated with the use of a viscous fluid coupling. Thus, a new electric motor, with variable frequency drive speed control was implemented. To address the issues with the inlet flow, the compressor is now driven from the rear resulting in improved inlet flow uniformity. This paper presents the design choices of the new layout in addition to the preliminary performance data of the compressor and an uncertainty analysis.

  19. High accuracy heat capacity measurements through the lambda transition of helium with very high temperature resolution

    NASA Technical Reports Server (NTRS)

    Fairbanks, W. M.; Lipa, J. A.

    1984-01-01

    A measurement of the heat capacity singularity of helium at the lambda transition was performed with the aim of improving tests of the Renormalization Group (RG) predictions for the static thermodynamic behavior near the singularity. The goal was to approach as closely as possible to the lambda-point while making heat capacity measurements of high accuracy. To do this, a new temperature sensor capable of unprecedented resolution near the lambda-point, and two thermal control systems were used. A short description of the theoretical background and motivation is given. The initial apparatus and results are also described.

  20. Self-mixing digital closed-loop vibrometer for high accuracy vibration measurements

    NASA Astrophysics Data System (ADS)

    Magnani, Alessandro; Melchionni, Dario; Pesatori, Alessandro; Norgia, Michele

    2016-04-01

    The novelty of Self-mixing interferometry is represented by the combination of high accuracy and contactless operation with compact, very-low-cost and user-friendly setup. This paper introduces state of the art techniques to monitor vibrations focusing on a novel digital feedback vibrometer. It exploits a control loop to delete interferometric signal distortion and improve measurement accuracy. A digital implementation is proposed to enhance system performances through a real-time elaboration.

  1. High-Accuracy Magnetic Field Measurements on Cool Giant β Geminorum

    NASA Astrophysics Data System (ADS)

    Baklanova, D. N.; Plachinda, S. I.

    2010-12-01

    Pollux is a weakly-active yellow gi ant neighbor of the Sun with known regular surface magnetic field about 1 Gauss. We present new high- accuracy magnetic field measurements of β Gem which were obtained during 2010 at Crimean Astrophysical Observatory with 2.6-m telescope and Stokesmeter.

  2. High accuracy acoustic relative humidity measurement in duct flow with air.

    PubMed

    van Schaik, Wilhelm; Grooten, Mart; Wernaart, Twan; van der Geld, Cees

    2010-01-01

    An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH) instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0-12 m/s with an error of ± 0.13 m/s, temperature 0-100 °C with an error of ± 0.07 °C and relative humidity 0-100% with accuracy better than 2 % RH above 50 °C. Main advantage over conventional humidity sensors is the high sensitivity at high RH at temperatures exceeding 50 °C, with accuracy increasing with increasing temperature. The sensors are non-intrusive and resist highly humid environments. PMID:22163610

  3. High Accuracy Acoustic Relative Humidity Measurement in Duct Flow with Air

    PubMed Central

    van Schaik, Wilhelm; Grooten, Mart; Wernaart, Twan; van der Geld, Cees

    2010-01-01

    An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH) instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0–12 m/s with an error of ±0.13 m/s, temperature 0–100 °C with an error of ±0.07 °C and relative humidity 0–100% with accuracy better than 2 % RH above 50 °C. Main advantage over conventional humidity sensors is the high sensitivity at high RH at temperatures exceeding 50 °C, with accuracy increasing with increasing temperature. The sensors are non-intrusive and resist highly humid environments. PMID:22163610

  4. Consideration for high accuracy radiation efficiency measurements for the Solar Power Satellite (SPS) subarrays

    NASA Technical Reports Server (NTRS)

    Kozakoff, D. J.; Schuchardt, J. M.; Ryan, C. E.

    1980-01-01

    The transmit beam and radiation efficiency for 10 metersquare subarray panels were quantified. Measurement performance potential of far field elevated and ground reflection ranges and near field technique were evaluated. The state-of-the-art of critical components and/or unique facilities required was identified. Relative cost, complexity and performance tradeoffs were performed for techniques capable of achieving accuracy objectives. It is considered that because of the large electrical size of the SPS subarray panels and the requirement for high accuracy measurements, specialized measurement facilities are required. Most critical measurement error sources have been identified for both conventional far field and near field techniques. Although the adopted error budget requires advances in state-of-the-art of microwave instrumentation, the requirements appear feasible based on extrapolation from today's technology. Additional performance and cost tradeoffs need to be completed before the choice of the preferred measurement technique is finalized.

  5. High accuracy differential pressure measurements using fluid-filled catheters - A feasibility study in compliant tubes.

    PubMed

    Rotman, Oren Moshe; Weiss, Dar; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

    2015-09-18

    High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes. The purpose of the present study was to test the feasibility of this correction method inside compliant tubes, which effectively simulate arteries. Two tubes with varying compliance were tested under dynamic flow and pressure conditions to cover the physiological range of radial distensibility in coronary arteries. A third, compliant model, with a 70% stenosis severity was additionally tested. Differential pressure measurements were acquired over a 3 cm tube length using a fluid-filled double-lumen catheter, and were corrected using the proposed CMP correction method. Validation of the corrected differential pressure signals was performed by comparison to differential pressure recordings taken via a direct connection to the compliant tubes, and by comparison to predicted differential pressure readings of matching fluid-structure interaction (FSI) computational simulations. The results show excellent agreement between the experimentally acquired and computationally determined differential pressure signals. This validates the application of the CMP correction method in compliant tubes of the physiological range for up to intermediate size stenosis severity of 70%. PMID:26087881

  6. High-accuracy thickness measurement of a transparent plate with the heterodyne central fringe identification technique

    SciTech Connect

    Wu, Wang-Tsung; Hsieh, Hung-Chih; Chang, Wei-Yao; Chen, Yen-Liang; Su, Der-Chin

    2011-07-20

    In a modified Twyman-Green interferometer, the optical path variation is measured with the heterodyne central fringe identification technique, as the light beam is focused by a displaced microscopic objective on the front/rear surface of the test transparent plate. The optical path length variation is then measured similarly after the test plate is removed. The geometrical thickness of the test plate can be calculated under the consideration of dispersion effect. This method has a wide measurable range and a high accuracy in the measurable range.

  7. Advanced video extensometer for non-contact, real-time, high-accuracy strain measurement.

    PubMed

    Pan, Bing; Tian, Long

    2016-08-22

    We developed an advanced video extensometer for non-contact, real-time, high-accuracy strain measurement in material testing. In the established video extensometer, a "near perfect and ultra-stable" imaging system, combining the idea of active imaging with a high-quality bilateral telecentric lens, is constructed to acquire high-fidelity video images of the test sample surface, which is invariant to ambient lighting changes and small out-of-plane motions occurred between the object surface and image plane. In addition, an efficient and accurate inverse compositional Gauss-Newton algorithm incorporating a temporal initial guess transfer scheme and a high-accuracy interpolation method is employed to achieve real-time, high-accuracy displacement tracking with negligible bias error. Tensile tests of an aluminum sample and a carbon fiber filament sample were performed to demonstrate the efficiency, repeatability and accuracy of the developed advanced video extensometer. The results indicate that longitudinal and transversal strains can be estimated and plotted at a rate of 117 fps and with a maximum strain error less than 30 microstrains. PMID:27557188

  8. Broadband EIT borehole measurements with high phase accuracy using numerical corrections of electromagnetic coupling effects

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zimmermann, E.; Huisman, J. A.; Treichel, A.; Wolters, B.; van Waasen, S.; Kemna, A.

    2013-08-01

    Electrical impedance tomography (EIT) is gaining importance in the field of geophysics and there is increasing interest for accurate borehole EIT measurements in a broad frequency range (mHz to kHz) in order to study subsurface properties. To characterize weakly polarizable soils and sediments with EIT, high phase accuracy is required. Typically, long electrode cables are used for borehole measurements. However, this may lead to undesired electromagnetic coupling effects associated with the inductive coupling between the double wire pairs for current injection and potential measurement and the capacitive coupling between the electrically conductive shield of the cable and the electrically conductive environment surrounding the electrode cables. Depending on the electrical properties of the subsurface and the measured transfer impedances, both coupling effects can cause large phase errors that have typically limited the frequency bandwidth of field EIT measurements to the mHz to Hz range. The aim of this paper is to develop numerical corrections for these phase errors. To this end, the inductive coupling effect was modeled using electronic circuit models, and the capacitive coupling effect was modeled by integrating discrete capacitances in the electrical forward model describing the EIT measurement process. The correction methods were successfully verified with measurements under controlled conditions in a water-filled rain barrel, where a high phase accuracy of 0.8 mrad in the frequency range up to 10 kHz was achieved. The corrections were also applied to field EIT measurements made using a 25 m long EIT borehole chain with eight electrodes and an electrode separation of 1 m. The results of a 1D inversion of these measurements showed that the correction methods increased the measurement accuracy considerably. It was concluded that the proposed correction methods enlarge the bandwidth of the field EIT measurement system, and that accurate EIT measurements can now

  9. Automation, Operation, and Data Analysis in the Cryogenic, High Accuracy, Refraction Measuring System (CHARMS)

    NASA Technical Reports Server (NTRS)

    Frey, Bradley J.; Leviton, Douglas B.

    2005-01-01

    The Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center has been enhanced in a number of ways in the last year to allow the system to accurately collect refracted beam deviation readings automatically over a range of temperatures from 15 K to well beyond room temperature with high sampling density in both wavelength and temperature. The engineering details which make this possible are presented. The methods by which the most accurate angular measurements are made and the corresponding data reduction methods used to reduce thousands of observed angles to a handful of refractive index values are also discussed.

  10. Automation, Operation, and Data Analysis in the Cryogenic, High Accuracy, Refraction Measuring System (CHARMS)

    NASA Technical Reports Server (NTRS)

    Frey, Bradley; Leviton, Duoglas

    2005-01-01

    The Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA s Goddard Space Flight Center has been enhanced in a number of ways in the last year to allow the system to accurately collect refracted beam deviation readings automatically over a range of temperatures from 15 K to well beyond room temperature with high sampling density in both wavelength and temperature. The engineering details which make this possible are presented. The methods by which the most accurate angular measurements are made and the corresponding data reduction methods used to reduce thousands of observed angles to a handful of refractive index values are also discussed.

  11. Measurement accuracy and Cerenkov removal for high performance, high spatial resolution scintillation dosimetry

    SciTech Connect

    Archambault, Louis; Beddar, A. Sam; Gingras, Luc

    2006-01-15

    With highly conformal radiation therapy techniques such as intensity-modulated radiation therapy, radiosurgery, and tomotherapy becoming more common in clinical practice, the use of these narrow beams requires a higher level of precision in quality assurance and dosimetry. Plastic scintillators with their water equivalence, energy independence, and dose rate linearity have been shown to possess excellent qualities that suit the most complex and demanding radiation therapy treatment plans. The primary disadvantage of plastic scintillators is the presence of Cerenkov radiation generated in the light guide, which results in an undesired stem effect. Several techniques have been proposed to minimize this effect. In this study, we compared three such techniques--background subtraction, simple filtering, and chromatic removal--in terms of reproducibility and dose accuracy as gauges of their ability to remove the Cerenkov stem effect from the dose signal. The dosimeter used in this study comprised a 6-mm{sup 3} plastic scintillating fiber probe, an optical fiber, and a color charge-coupled device camera. The whole system was shown to be linear and the total light collected by the camera was reproducible to within 0.31% for 5-s integration time. Background subtraction and chromatic removal were both found to be suitable for precise dose evaluation, with average absolute dose discrepancies of 0.52% and 0.67%, respectively, from ion chamber values. Background subtraction required two optical fibers, but chromatic removal used only one, thereby preventing possible measurement artifacts when a strong dose gradient was perpendicular to the optical fiber. Our findings showed that a plastic scintillation dosimeter could be made free of the effect of Cerenkov radiation.

  12. 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.

  13. 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. PMID:18052471

  14. High-accuracy inspection of defects and profile of wafers by phase measuring deflectometry

    NASA Astrophysics Data System (ADS)

    Yue, Huimin; Wu, Yuxiang; Zhao, Biyu; Ou, Zhonghua; Liu, Yong

    2014-09-01

    The demands of the less-defective and high-flatness wafers are urgent in many wafer based technologies ranging from micro-electronics to the current photovoltaic industry. As the wafer becomes thinner and larger to cope with the advances in those industries, there is an increasing possibility of the emerging of crack and warp on the wafer surface. High-accuracy inspection of defects and profile are thus necessary to ensure the reliability of device. Phase measuring deflectometry(PMD) is a fast, cost-effective and high accuracy measurement technology which has been developed in recent years. As a slope measurement technology, PMD possesses a high sensitivity. Very small slope variation will lead to a large variation of the phase. PMD is very possible to have a good performance in the wafer inspection. In this paper, the requirements of the wafer inspection in the industries are discussed, and compatibility of PMD and those requirements is analyzed. In the experimental work, PMD gets the slope information of the wafer surface directly. The curvature or height information can be acquired simply by the derivation or integral of the slope. PMD is proved to make a superior result in high-precision defect detecting and shape measurement of wafer by the analysis of experiment results.

  15. Real-time, high-accuracy 3D imaging and shape measurement.

    PubMed

    Nguyen, Hieu; Nguyen, Dung; Wang, Zhaoyang; Kieu, Hien; Le, Minh

    2015-01-01

    In spite of the recent advances in 3D shape measurement and geometry reconstruction, simultaneously achieving fast-speed and high-accuracy performance remains a big challenge in practice. In this paper, a 3D imaging and shape measurement system is presented to tackle such a challenge. The fringe-projection-profilometry-based system employs a number of advanced approaches, such as: composition of phase-shifted fringe patterns, externally triggered synchronization of system components, generalized system setup, ultrafast phase-unwrapping algorithm, flexible system calibration method, robust gamma correction scheme, multithread computation and processing, and graphics-processing-unit-based image display. Experiments have shown that the proposed system can acquire and display high-quality 3D reconstructed images and/or video stream at a speed of 45 frames per second with relative accuracy of 0.04% or at a reduced speed of 22.5 frames per second with enhanced accuracy of 0.01%. The 3D imaging and shape measurement system shows great promise of satisfying the ever-increasing demands of scientific and engineering applications. PMID:25967028

  16. High-accuracy and cost-effective photodiode spectral response measurement system

    NASA Astrophysics Data System (ADS)

    Chang, Gao-Wei; Liao, Chia-Cheng; Yeh, Zong-Mu

    2007-02-01

    With the rapid growth of optoelectronics technologies, photodiodes (PDs) has been widely used in optical measurement systems, color measurement and analysis systems, etc. To meet most of the measurement requirements, the determination of PD spectral responses is very important. The goal of this paper is to develop a high-accuracy and cost-effective spectral response measurement system for PDs. In this paper, the proposed system contains a grating-based spectral filtering module, an amplifier module, and a digital-signal-processing (DSP) based platform. In the spectral filtering module, a single-grating monochromator based on a Czerny-Turner configuration is first analyzed and simulated, and then the experiments are conducted to check if the measurement accuracy is satisfactory. In the measurement system, optoelectronic signals from the PD under test are acquired from the amplifier module and the DSP-based platform is developed to communicate and manipulate the measured data. Through comparison with the measurement data from a commercially available system, it is found that our approach gives quite satisfactory results.

  17. High Accuracy, Absolute, Cryogenic Refractive Index Measurements of Infrared Lens Materials for JWST NIRCam using CHARMS

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas; Frey, Bradley

    2005-01-01

    The current refractive optical design of the James Webb Space Telescope (JWST) Near Infrared Camera (NIRCam) uses three infrared materials in its lenses: LiF, BaF2, and ZnSe. In order to provide the instrument s optical designers with accurate, heretofore unavailable data for absolute refractive index based on actual cryogenic measurements, two prismatic samples of each material were measured using the cryogenic, high accuracy, refraction measuring system (CHARMS) at NASA GSFC, densely covering the temperature range from 15 to 320 K and wavelength range from 0.4 to 5.6 microns. Measurement methods are discussed and graphical and tabulated data for absolute refractive index, dispersion, and thermo-optic coefficient for these three materials are presented along with estimates of uncertainty. Coefficients for second order polynomial fits of measured index to temperature are provided for many wavelengths to allow accurate interpolation of index to other wavelengths and temperatures.

  18. High accuracy thermal conductivity measurements near the lambda transition of helium with very high temperature resolution

    NASA Technical Reports Server (NTRS)

    Fairbank, William M.; Lipa, John A.

    1989-01-01

    Over the past few years extensive thermal conductivity measurements near the lambda point of helium were made. The original goal of measuring the thermal conductivity with a resolution of t = T/T sub lambda -1 of 3 x 10(-8) was reached, but with somewhat less accuracy than was hoped. Subtle effects in the apparatus near the transition were observed which reduced the ability to interpret the results. Nevertheless, for resolution of t is greater than or equal to 10(-7) reliable data was obtained, extending previous measurements by more than an order of magnitude. Deviations from theoretical predictions were observed for t is less than or equal to 3 x 10(-6) leading to the question of the validity of the present renormalization group analysis of transport properties, at least for the case of helium. This anomaly led to closer examination of the boundary effects in the measurements. During the experiments a totally unexpected effect in the very dilute He-3 - He-4 mixtures was observed which led to the explanation of the anomalous results. The concentration dependence of the thermal conductivity near T sub lambda in the superfluid phase was found to deviate strongly from the predictions. The results gave an independent verification of this behavior and caused reanalysis of the Khalatnikov theory of hydrodynamics of the mixtures. An alternative solution was found which is in better agreement with the experiment.

  19. Accuracy of GPS devices for measuring high-intensity running in field-based team sports.

    PubMed

    Rampinini, E; Alberti, G; Fiorenza, M; Riggio, M; Sassi, R; Borges, T O; Coutts, A J

    2015-01-01

    We compared the accuracy of 2 GPS systems with different sampling rates for the determination of distances covered at high-speed and metabolic power derived from a combination of running speed and acceleration. 8 participants performed 56 bouts of shuttle intermittent running wearing 2 portable GPS devices (SPI-Pro, GPS-5 Hz and MinimaxX, GPS-10 Hz). The GPS systems were compared with a radar system as a criterion measure. The variables investigated were: total distance (TD), high-speed distance (HSR>4.17 m·s(-1)), very high-speed distance (VHSR>5.56 m·s(-1)), mean power (Pmean), high metabolic power (HMP>20 W·kg(-1)) and very high metabolic power (VHMP>25 W·kg(-1)). GPS-5 Hz had low error for TD (2.8%) and Pmean (4.5%), while the errors for the other variables ranged from moderate to high (7.5-23.2%). GPS-10 Hz demonstrated a low error for TD (1.9%), HSR (4.7%), Pmean (2.4%) and HMP (4.5%), whereas the errors for VHSR (10.5%) and VHMP (6.2%) were moderate. In general, GPS accuracy increased with a higher sampling rate, but decreased with increasing speed of movement. Both systems could be used for calculating TD and Pmean, but they cannot be used interchangeably. Only GPS-10 Hz demonstrated a sufficient level of accuracy for quantifying distance covered at higher speeds or time spent at very high power. PMID:25254901

  20. On the Benefits of Acquiring Peptide Fragment Ions at High Measured Mass Accuracy

    PubMed Central

    Scherl, Alexander; Shaffer, Scott A.; Taylor, Gregory K.; Hernandez, Patricia; Appel, Ron D.; Binz, Pierre-Alain; Goodlett, David R.

    2008-01-01

    The advantages and disadvantages of acquiring tandem mass spectra by collision-induced dissociation (CID) of peptides in linear ion trap – Fourier-transform hybrid instruments are described. These instruments offer the possibility to transfer fragment ions from the linear ion trap to the FT-based analyzer for analysis with both high resolution and high mass accuracy. In addition, performing CID during the transfer of ions from the linear ion trap (LTQ) to the FT analyzer is also possible in instruments containing an additional collision cell (i.e., the “C-trap” in the LTQ-Orbitrap), resulting in tandem mass spectra over the full m/z range and not limited by the ejection q value of the LTQ. Our results show that these scan modes have lower duty cycles than tandem mass spectra acquired in the LTQ with nominal mass resolution, and typically result in fewer peptide identifications during data-dependent analysis of complex samples. However, the higher measured mass accuracy and resolution provides more specificity and hence provides a lower false positive ratio for the same number of true positives during database search of peptide tandem mass spectra. In addition, the search for modified and unexpected peptides is greatly facilitated with this data acquisition mode. It is therefore concluded that acquisition of tandem mass spectral data with high measured mass accuracy and resolution is a competitive alternative to “classical” data acquisition strategies, especially in situations of complex searches from large databases, searches for modified peptides, or for peptides resulting from unspecific cleavages. PMID:18417358

  1. Measuring droplet fall speed with a high-speed camera: indoor accuracy and potential outdoor applications

    NASA Astrophysics Data System (ADS)

    Yu, Cheng-Ku; Hsieh, Pei-Rong; Yuter, Sandra E.; Cheng, Lin-Wen; Tsai, Chia-Lun; Lin, Che-Yu; Chen, Ying

    2016-04-01

    Acquisition of accurate raindrop fall speed measurements outdoors in natural rain by means of moderate-cost and easy-to-use devices represents a long-standing and challenging issue in the meteorological community. Feasibility experiments were conducted to evaluate the indoor accuracy of fall speed measurements made with a high-speed camera and to evaluate its capability for outdoor applications. An indoor experiment operating in calm conditions showed that the high-speed imaging technique can provide fall speed measurements with a mean error of 4.1-9.7 % compared to Gunn and Kinzer's empirical fall-speed-size relationship for typical sizes of rain and drizzle drops. Results obtained using the same apparatus outside in summer afternoon showers indicated larger positive and negative velocity deviations compared to the indoor measurements. These observed deviations suggest that ambient flow and turbulence play a role in modifying drop fall speeds which can be quantified with future outdoor high-speed camera measurements. Because the fall speed measurements, as presented in this article, are analyzed on the basis of tracking individual, specific raindrops, sampling uncertainties commonly found in the widely adopted optical disdrometers can be significantly mitigated.

  2. High-accuracy measurement of low-water-content in liquid using NIR spectral absorption method

    NASA Astrophysics Data System (ADS)

    Peng, Bao-Jin; Wan, Xu; Jin, Hong-Zhen; Zhao, Yong; Mao, He-Fa

    2005-01-01

    Water content measurement technologies are very important for quality inspection of food, medicine products, chemical products and many other industry fields. In recent years, requests for accurate low-water-content measurement in liquid are more and more exigent, and great interests have been shown from the research and experimental work. With the development and advancement of modern production and control technologies, more accurate water content technology is needed. In this paper, a novel experimental setup based on near-infrared (NIR) spectral technology and fiber-optic sensor (OFS) is presented. It has a good measurement accuracy about -/+ 0.01%, which is better, to our knowledge, than most other methods published until now. It has a high measurement resolution of 0.001% in the measurement range from zero to 0.05% for water-in-alcohol measurement, and the water-in-oil measurement is carried out as well. In addition, the advantages of this method also include pollution-free to the measured liquid, fast measurement and so on.

  3. Innovative High-Accuracy Lidar Bathymetric Technique for the Frequent Measurement of River Systems

    NASA Astrophysics Data System (ADS)

    Gisler, A.; Crowley, G.; Thayer, J. P.; Thompson, G. S.; Barton-Grimley, R. A.

    2015-12-01

    Lidar (light detection and ranging) provides absolute depth and topographic mapping capability compared to other remote sensing methods, which is useful for mapping rapidly changing environments such as riverine systems. Effectiveness of current lidar bathymetric systems is limited by the difficulty in unambiguously identifying backscattered lidar signals from the water surface versus the bottom, limiting their depth resolution to 0.3-0.5 m. Additionally these are large, bulky systems that are constrained to expensive aircraft-mounted platforms and use waveform-processing techniques requiring substantial computation time. These restrictions are prohibitive for many potential users. A novel lidar device has been developed that allows for non-contact measurements of water depth down to 1 cm with an accuracy and precision of < 1 cm by exploiting the polarization properties of the light-surface interaction. This system can transition seamlessly from ranging over land to shallow to deep water allowing for shoreline charting, measuring water volume, mapping bottom topology, and identifying submerged objects. The scalability of the technique opens up the ability for handheld or UAS-mounted lidar bathymetric systems, which provides for potential applications currently unavailable to the community. The high laser pulse repetition rate allows for very fine horizontal resolution while the photon-counting technique permits real-time depth measurement and object detection. The enhanced measurement capability, portability, scalability, and relatively low-cost creates the opportunity to perform frequent high-accuracy monitoring and measuring of aquatic environments which is crucial for understanding how rivers evolve over many timescales. Results from recent campaigns measuring water depth in flowing creeks and murky ponds will be presented which demonstrate that the method is not limited by rough water surfaces and can map underwater topology through moderately turbid water.

  4. A high-resolution measurement device for detecting the positioning accuracy of the optical fiber positioner

    NASA Astrophysics Data System (ADS)

    Gu, Yonggang; Xu, Jianlei; Jin, Yi; Zhai, Chao

    2012-09-01

    The optical fiber positioner with double revolving mechanism is driven by two stepping motors. One stepping motor drives center revolving mechanism and the other drives decentered slewing mechanism. Photogrammetry is currently used to detect the positioning accuracy of the optical fiber positioner, but it cannot achieve high precision because of the small size of the fiber’s diameter. So, a new measurement device, which mainly contained optical microscope, CCD camera and two-dimensional precision mobile platform, was established in this paper. One end of the optical fiber (the other end was lighted by integrating sphere light source) was imaged on the CCD sensor in a magnified way through the optical microscope, and the image was processed to build the position feedback mechanism in real time. Then the two-dimensional mobile platform was controlled by PID control method to track the optical fiber, and the fiber was always kept to locate in center of the CCD image in order to eliminate the aberrations of the optical microscope lens. Finally, the position changes of the moving fiber could be obtained by the coordinates of the two-dimensional precision mobile platform. The experimental results demonstrate that the resolution of this measurement device is 0.1μm and the accuracy of repeat positioning is 1.5μm. The measurement device could satisfy the testing requirement.

  5. Detailed high-accuracy megavoltage transmission measurements: A sensitive experimental benchmark of EGSnrc

    SciTech Connect

    Ali, E. S. M.; McEwen, M. R.; Rogers, D. W. O.

    2012-10-15

    Purpose: There are three goals for this study: (a) to perform detailed megavoltage transmission measurements in order to identify the factors that affect the measurement accuracy, (b) to use the measured data as a benchmark for the EGSnrc system in order to identify the computational limiting factors, and (c) to provide data for others to benchmark Monte Carlo codes. Methods: Transmission measurements are performed at the National Research Council Canada on a research linac whose incident electron parameters are independently known. Automated transmission measurements are made on-axis, down to a transmission value of {approx}1.7%, for eight beams between 10 MV (the lowest stable MV beam on the linac) and 30 MV, using fully stopping Be, Al, and Pb bremsstrahlung targets and no fattening filters. To diversify energy differentiation, data are acquired for each beam using low-Z and high-Z attenuators (C and Pb) and Farmer chambers with low-Z and high-Z buildup caps. Experimental corrections are applied for beam drifts (2%), polarity (2.5% typical maximum, 6% extreme), ion recombination (0.2%), leakage (0.3%), and room scatter (0.8%)-the values in parentheses are the largest corrections applied. The experimental setup and the detectors are modeled using EGSnrc, with the newly added photonuclear attenuation included (up to a 5.6% effect). A detailed sensitivity analysis is carried out for the measured and calculated transmission data. Results: The developed experimental protocol allows for transmission measurements with 0.4% uncertainty on the smallest signals. Suggestions for accurate transmission measurements are provided. Measurements and EGSnrc calculations agree typically within 0.2% for the sensitivity of the transmission values to the detector details, to the bremsstrahlung target material, and to the incident electron energy. Direct comparison of the measured and calculated transmission data shows agreement better than 2% for C (3.4% for the 10 MV beam) and

  6. High accuracy die mechanical stress measurement with the ATC04 Assembly Test Chip

    NASA Astrophysics Data System (ADS)

    Sweet, J. N.; Peterson, D. W.

    1993-07-01

    We have designed and manufactured a new CMOS piezoresistive stress sensing chip, ATC04, with an advanced cell design which enables stress measurement to much higher accuracy and precision than any other known die.

  7. Development of a High Accuracy Angular Measurement System for Langley Research Center Hypersonic Wind Tunnel Facilities

    NASA Technical Reports Server (NTRS)

    Newman, Brett; Yu, Si-bok; Rhew, Ray D. (Technical Monitor)

    2003-01-01

    Modern experimental and test activities demand innovative and adaptable procedures to maximize data content and quality while working within severely constrained budgetary and facility resource environments. This report describes development of a high accuracy angular measurement capability for NASA Langley Research Center hypersonic wind tunnel facilities to overcome these deficiencies. Specifically, utilization of micro-electro-mechanical sensors including accelerometers and gyros, coupled with software driven data acquisition hardware, integrated within a prototype measurement system, is considered. Development methodology addresses basic design requirements formulated from wind tunnel facility constraints and current operating procedures, as well as engineering and scientific test objectives. Description of the analytical framework governing relationships between time dependent multi-axis acceleration and angular rate sensor data and the desired three dimensional Eulerian angular state of the test model is given. Calibration procedures for identifying and estimating critical parameters in the sensor hardware is also addressed.

  8. Accuracy of axial length measurements from immersion B-scan ultrasonography in highly myopic eyes

    PubMed Central

    Yang, Qing-Hua; Chen, Bing; Peng, Guang-Hua; Li, Zhao-Hui; Huang, Yi-Fei

    2014-01-01

    AIM To evaluate the accuracy of axial length (AL) measurements obtained from immersion B-scan ultrasonography (immersion B-scan) for intraocular lens (IOL) power calculation in patients with high myopia and cataracts. METHODS Immersion B-scan, contact A-scan ultrasonography (contact A-scan), and the IOLMaster were used to preoperatively measure the AL in 102 eyes from 102 patients who underwent phacoemulsification and IOL implantation. Patients were divided into two groups according to the AL: one containing patients with 22 mm≤AL<26 mm(group A) and the other containing patients with AL≥26 mm (group B). The mean error (ME) was calculated from the difference between the AL measurement methods predicted refractive error and the actual postoperative refractive error. RESULTS In group A, ALs measured by immersion B-scan (23.48±1.15) didn't differ significantly from those measured by the IOLMaster (23.52±1.17) or from those by contact A-scan (23.38±1.20). In the same group, the standard deviation (SD) of the mean error (ME) of immersion B-scan (-0.090±0.397 D) didn't differ significantly from those of IOLMaster (-0.095±0.411 D) and contact A-scan (-0.099±0.425 D). In group B, ALs measured by immersion B-scan (27.97±2.21 mm) didn't differ significantly from those of the IOLMaster (27.86±2.18 mm), but longer than those measured by Contact A-scan (27.75±2.23 mm, P=0.009). In the same group, the standard deviation (SD) of the mean error (ME) of immersion B-scan (-0.635±0.157 D) didn't differ significantly from those of the IOLMaster (-0.679±0.359 D), but differed significantly from those of contact A-scan (-0.953±1.713 D, P=0.028). CONCLUSION Immersion B-scan exhibits measurement accuracy comparable to that of the IOLMaster, and is thus a good alternative in measuring AL in eyes with high myopia when the IOLMaster can't be used, and it is more accurate than the contact A-scan. PMID:24967188

  9. High-accuracy direct ZT and intrinsic properties measurement of thermoelectric couple devices.

    PubMed

    Kraemer, D; Chen, G

    2014-04-01

    Advances in thermoelectric materials in recent years have led to significant improvements in thermoelectric device performance and thus, give rise to many new potential applications. In order to optimize a thermoelectric device for specific applications and to accurately predict its performance ideally the material's figure of merit ZT as well as the individual intrinsic properties (Seebeck coefficient, electrical resistivity, and thermal conductivity) should be known with high accuracy. For that matter, we developed two experimental methods in which the first directly obtains the ZT and the second directly measures the individual intrinsic leg properties of the same p/n-type thermoelectric couple device. This has the advantage that all material properties are measured in the same sample direction after the thermoelectric legs have been mounted in the final device. Therefore, possible effects from crystal anisotropy and from the device fabrication process are accounted for. The Seebeck coefficients, electrical resistivities, and thermal conductivities are measured with differential methods to minimize measurement uncertainties to below 3%. The thermoelectric couple ZT is directly measured with a differential Harman method which is in excellent agreement with the calculated ZT from the individual leg properties. The errors in both the directly measured and calculated thermoelectric couple ZT are below 5% which is significantly lower than typical uncertainties using commercial methods. Thus, the developed technique is ideal for characterizing assembled couple devices and individual thermoelectric materials and enables accurate device optimization and performance predictions. We demonstrate the methods by measuring a p/n-type thermoelectric couple device assembled from commercial bulk thermoelectric Bi2Te3 elements in the temperature range of 30 °C-150 °C and discuss the performance of the couple thermoelectric generator in terms of its efficiency and materials

  10. Considerations for high accuracy radiation efficiency measurements for the Solar Power Satellite (SPS) subarrays

    NASA Technical Reports Server (NTRS)

    Kozakoff, D. J.; Schuchardt, J. M.; Ryan, C. E.

    1980-01-01

    The relatively large apertures to be used in SPS, small half-power beamwidths, and the desire to accurately quantify antenna performance dictate the requirement for specialized measurements techniques. Objectives include the following: (1) For 10-meter square subarray panels, quantify considerations for measuring power in the transmit beam and radiation efficiency to + or - 1 percent (+ or - 0.04 dB) accuracy. (2) Evaluate measurement performance potential of far-field elevated and ground reflection ranges and near-field techniques. (3) Identify the state-of-the-art of critical components and/or unique facilities required. (4) Perform relative cost, complexity and performance tradeoffs for techniques capable of achieving accuracy objectives. the precision required by the techniques discussed below are not obtained by current methods which are capable of + or - 10 percent (+ or - dB) performance. In virtually every area associated with these planned measurements, advances in state-of-the-art are required.

  11. High-Accuracy Measurements of the Centre of Gravity of Avalanches in Proportional Chambers

    DOE R&D Accomplishments Database

    Charpak, G.; Jeavons, A.; Sauli, F.; Stubbs, R.

    1973-09-24

    In a multiwire proportional chamber the avalanches occur close to the anode wires. The motion of the positive ions in the large electric fields at the vicinity of the wires induces fast-rising positive pulses on the surrounding electrodes. Different methods have been developed in order to determine the position of the centre of the avalanches. In the method we describe, the centre of gravity of the pulse distribution is measured directly. It seems to lead to an accuracy which is limited only by the stability of the spatial distribution of the avalanches generated by the process being measured.

  12. A high-accuracy calibration technique for thermochromic liquid crystal temperature measurements

    NASA Astrophysics Data System (ADS)

    Sabatino, D. R.; Praisner, T. J.; Smith, C. R.

    There are a variety of phenomena which may impact the accuracy of wide-band thermochromic liquid crystal temperature measurements, including: irregularities in liquid crystal and black paint layers, reflective components from light sources, and variations in the lighting/viewing angle across the surface. A wide-band calibration technique has been developed which inherently accounts for these and other sources of uncertainty by employing a point-wise calibration of the entire test surface. Both on and off-axis lighting arrangements are assessed for ease of implementation and accuracy of color displayed under uniform temperature conditions. The technique employs a series of uniform-temperature images to construct calibration curves relating the local hue component to temperature in a point-wise manner for the entire test surface. An off-axis lighting/viewing arrangement is found to be most practical for typical experimental setups. Hysteresis effects are quantified for excursions beyond both the lower and upper clearing point of the liquid crystals. Finally, the total uncertainty of the measured temperature is determined to vary from +/-1.2% to +/-7.2% across the bandwidth of the liquid crystals.

  13. a Method to Achieve Large Volume, High Accuracy Photogrammetric Measurements Through the Use of AN Actively Deformable Sensor Mounting Platform

    NASA Astrophysics Data System (ADS)

    Sargeant, B.; Robson, S.; Szigeti, E.; Richardson, P.; El-Nounu, A.; Rafla, M.

    2016-06-01

    When using any optical measurement system one important factor to consider is the placement of the sensors in relation to the workpiece being measured. When making decisions on sensor placement compromises are necessary in selecting the best placement based on the shape and size of the object of interest and the desired resolution and accuracy. One such compromise is in the distance the sensors are placed from the measurement surface, where a smaller distance gives a higher spatial resolution and local accuracy and a greater distance reduces the number of measurements necessary to cover a large area reducing the build-up of errors between measurements and increasing global accuracy. This paper proposes a photogrammetric approach whereby a number of sensors on a continuously flexible mobile platform are used to obtain local measurements while the position of the sensors is determined by a 6DoF tracking solution and the results combined to give a single set of measurement data within a continuous global coordinate system. The ability of this approach to achieve both high accuracy measurement and give results over a large volume is then tested and areas of weakness to be improved upon are identified.

  14. High-accuracy time- and space-resolved Stark shift measurements

    SciTech Connect

    Bailey, J.E.; Adams, R.; Carlson, A.L.; Ching, C.H.; Filuk, A.B.; Lake, P.

    1996-07-01

    Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. The authors use simultaneous 2-D-spatial and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion variation, and sensitivity. A semi-automated line-fitting procedure determines the Stark shift and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {+-}2--4%. Detailed tests of the fitting procedure confirm that the wavelength shift uncertainties are accurate to better than {+-}20%. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain 3-D space- and time-resolved measurements of the electric and magnetic fields is in progress.

  15. Towards a magnetic field stabilization at ISOLTRAP for high-accuracy mass measurements on exotic nuclides

    NASA Astrophysics Data System (ADS)

    Marie-Jeanne, M.; Alonso, J.; Blaum, K.; Djekic, S.; Dworschak, M.; Hager, U.; Herlert, A.; Nagy, Sz.; Savreux, R.; Schweikhard, L.; Stahl, S.; Yazidjian, C.

    2008-03-01

    The field stability of a mass spectrometer plays a crucial role in the accuracy of mass measurements. In the case of mass determination of short-lived nuclides with a Penning trap, major causes of fluctuations are temperature variations in the vicinity of the trap and pressure changes in the liquid helium cryostat of the superconducting magnet. Thus systems for the temperature and pressure stabilization of the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN have been installed. A reduction of the temperature and pressure fluctuations by at least an order of magnitude down to ΔT≈±5 mK and Δp≈±5 Pa has been achieved, which corresponds to a relative magnetic field change of ΔB/B=2.7×10-9 and 1.1×10-10, respectively.

  16. A high accuracy sun sensor

    NASA Astrophysics Data System (ADS)

    Bokhove, H.

    The High Accuracy Sun Sensor (HASS) is described, concentrating on measurement principle, the CCD detector used, the construction of the sensorhead and the operation of the sensor electronics. Tests on a development model show that the main aim of a 0.01-arcsec rms stability over a 10-minute period is closely approached. Remaining problem areas are associated with the sensor sensitivity to illumination level variations, the shielding of the detector, and the test and calibration equipment.

  17. Increasing Accuracy in Environmental Measurements

    NASA Astrophysics Data System (ADS)

    Jacksier, Tracey; Fernandes, Adelino; Matthew, Matt; Lehmann, Horst

    2016-04-01

    Human activity is increasing the concentrations of green house gases (GHG) in the atmosphere which results in temperature increases. High precision is a key requirement of atmospheric measurements to study the global carbon cycle and its effect on climate change. Natural air containing stable isotopes are used in GHG monitoring to calibrate analytical equipment. This presentation will examine the natural air and isotopic mixture preparation process, for both molecular and isotopic concentrations, for a range of components and delta values. The role of precisely characterized source material will be presented. Analysis of individual cylinders within multiple batches will be presented to demonstrate the ability to dynamically fill multiple cylinders containing identical compositions without isotopic fractionation. Additional emphasis will focus on the ability to adjust isotope ratios to more closely bracket sample types without the reliance on combusting naturally occurring materials, thereby improving analytical accuracy.

  18. Neutrino mass from cosmology: impact of high-accuracy measurement of the Hubble constant

    SciTech Connect

    Sekiguchi, Toyokazu; Ichikawa, Kazuhide; Takahashi, Tomo; Greenhill, Lincoln E-mail: kazuhide@me.kyoto-u.ac.jp E-mail: greenhill@cfa.harvard.edu

    2010-03-01

    Non-zero neutrino mass would affect the evolution of the Universe in observable ways, and a strong constraint on the mass can be achieved using combinations of cosmological data sets. We focus on the power spectrum of cosmic microwave background (CMB) anisotropies, the Hubble constant H{sub 0}, and the length scale for baryon acoustic oscillations (BAO) to investigate the constraint on the neutrino mass, m{sub ν}. We analyze data from multiple existing CMB studies (WMAP5, ACBAR, CBI, BOOMERANG, and QUAD), recent measurement of H{sub 0} (SHOES), with about two times lower uncertainty (5 %) than previous estimates, and recent treatments of BAO from the Sloan Digital Sky Survey (SDSS). We obtained an upper limit of m{sub ν} < 0.2eV (95 % C.L.), for a flat ΛCDM model. This is a 40 % reduction in the limit derived from previous H{sub 0} estimates and one-third lower than can be achieved with extant CMB and BAO data. We also analyze the impact of smaller uncertainty on measurements of H{sub 0} as may be anticipated in the near term, in combination with CMB data from the Planck mission, and BAO data from the SDSS/BOSS program. We demonstrate the possibility of a 5σ detection for a fiducial neutrino mass of 0.1 eV or a 95 % upper limit of 0.04 eV for a fiducial of m{sub ν} = 0 eV. These constraints are about 50 % better than those achieved without external constraint. We further investigate the impact on modeling where the dark-energy equation of state is constant but not necessarily -1, or where a non-flat universe is allowed. In these cases, the next-generation accuracies of Planck, BOSS, and 1 % measurement of H{sub 0} would all be required to obtain the limit m{sub ν} < 0.05−0.06 eV (95 % C.L.) for the fiducial of m{sub ν} = 0 eV. The independence of systematics argues for pursuit of both BAO and H{sub 0} measurements.

  19. Influence of measuring algorithm on shape accuracy in the compensating turning of high gradient thin-wall parts

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Wang, Guilin; Zhu, Dengchao; Li, Shengyi

    2015-02-01

    In order to meet the requirement of aerodynamics, the infrared domes or windows with conformal and thin-wall structure becomes the development trend of high-speed aircrafts in the future. But these parts usually have low stiffness, the cutting force will change along with the axial position, and it is very difficult to meet the requirement of shape accuracy by single machining. Therefore, on-machine measurement and compensating turning are used to control the shape errors caused by the fluctuation of cutting force and the change of stiffness. In this paper, on the basis of ultra precision diamond lathe, a contact measuring system with five DOFs is developed to achieve on-machine measurement of conformal thin-wall parts with high accuracy. According to high gradient surface, the optimizing algorithm is designed on the distribution of measuring points by using the data screening method. The influence rule of sampling frequency is analyzed on measuring errors, the best sampling frequency is found out based on planning algorithm, the effect of environmental factors and the fitting errors are controlled within lower range, and the measuring accuracy of conformal dome is greatly improved in the process of on-machine measurement. According to MgF2 conformal dome with high gradient, the compensating turning is implemented by using the designed on-machine measuring algorithm. The shape error is less than PV 0.8μm, greatly superior compared with PV 3μm before compensating turning, which verifies the correctness of measuring algorithm.

  20. Algorithms for Low-Cost High Accuracy Geomagnetic Measurements in LEO

    NASA Astrophysics Data System (ADS)

    Beach, T. L.; Zesta, E.; Allen, L.; Chepko, A.; Bonalsky, T.; Wendel, D. E.; Clavier, O.

    2013-12-01

    Geomagnetic field measurements are a fundamental, key parameter measurement for any space weather application, particularly for tracking the electromagnetic energy input in the Ionosphere-Thermosphere system and for high latitude dynamics governed by the large-scale field-aligned currents. The full characterization of the Magnetosphere-Ionosphere-Thermosphere coupled system necessitates measurements with higher spatial/temporal resolution and from multiple locations simultaneously. This becomes extremely challenging in the current state of shrinking budgets. Traditionally, including a science-grade magnetometer in a mission necessitates very costly integration and design (sensor on long boom) and imposes magnetic cleanliness restrictions on all components of the bus and payload. This work presents an innovative algorithm approach that enables high quality magnetic field measurements by one or more high-quality magnetometers mounted on the spacecraft without booms. The algorithm estimates the background field using multiple magnetometers and current telemetry on board a spacecraft. Results of a hardware-in-the-loop simulation showed an order of magnitude reduction in the magnetic effects of spacecraft onboard time-varying currents--from 300 nT to an average residual of 15 nT.

  1. 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.

  2. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement

    PubMed Central

    van den Berg, Steven. A.; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-01-01

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10−8 for a distance of 50 m. PMID:26419282

  3. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement

    NASA Astrophysics Data System (ADS)

    van den Berg, Steven. A.; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-09-01

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10-8 for a distance of 50 m.

  4. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement.

    PubMed

    van den Berg, Steven A; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-01-01

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10(-8) for a distance of 50 m. PMID:26419282

  5. Improved protein identification using automated high mass measurement accuracy MALDI FT-ICR MS peptide mass fingerprinting

    NASA Astrophysics Data System (ADS)

    Horn, David M.; Peters, Eric C.; Klock, Heath; Meyers, Andrew; Brock, Ansgar

    2004-11-01

    A comparison between automated peptide mass fingerprinting systems using MALDI-TOF and MALDI FT-ICR MS is presented using 86 overexpressed proteins from Thermotoga maritima. The high mass measurement accuracy of FT-ICR MS greatly reduces the probability of an incorrect assignment of a protein in peptide mass fingerprinting by significantly decreasing the score and peptide sequence coverage of the highest ranked random protein match from the database. This improved mass accuracy led to the identification of all 86 proteins with the FT-ICR data versus 84 proteins using the TOF data against the T. maritima database. The beneficial effect of mass accuracy becomes much more evident with the addition of variable modifications and an increase in the size of the database used in the search. A search of the same data against the T. maritima database with the addition of a variable modification resulted in 77 identifications using MALDI-TOF and 84 identifications using MALDI FT-ICR MS. When searching the NCBInr database, the FT-ICR based system identified 82 of 86 proteins while the TOF based system could only identify 73. The MALDI FT-ICR based system has the further advantage of producing fewer unassigned masses in each peptide mass fingerprint, resulting in greatly reduced sequence coverage and score for the highest ranked random match and improving confidence in the correctly assigned top scoring protein. Finally, the use of rms error as a measure for instrumental mass accuracy is discussed.

  6. An updated T-series thermocouple measurement system for high-accuracy temperature measurements of the MMT primary mirror

    NASA Astrophysics Data System (ADS)

    Clark, D.; Gibson, J. D.

    2012-09-01

    Starting in 2009, MMTO began design and installation of a new set of electronics to measure a set of radiallydistributed type T thermocouples installed after the primary mirror polishing was completed. These thermocouples are arranged in both single measurement points and as thermopiles for differential temperature sensing. Since the goal of the primary mirror temperature control system is to minimize mirror seeing and mirror figure errors induced by temperature variation across the primary mirror, it depends on excellent accuracy from the temperature sensing system. The new electronics encompass on-board cold-junction compensation, real-time ITS-90 curve fitting, and Ethernet connectivity to the data servers running in the MMTO software infrastructure. We describe the hardware design, system wiring, and software used in this system.

  7. On the Accuracy of Stratospheric Meteorological Reanalyses Using Wind Measurements at High Altitude in the Stratosphere

    NASA Astrophysics Data System (ADS)

    Huret, N.; Duruisseau, F.; Andral, A.

    2015-09-01

    This study is motivated by the improvement of the knowledge of stratospheric dynamics and the evaluation of the ability of models to represent wind variability in the stratosphere. We deduce from the Zero Pressure Balloons trajectories, operated by CNES during the last decade, zonal and meridional wind to provide a unique database in the altitude range [25-40] km. The collected data are associated with ZBP flights launch during winter and summer in polar region above the Esrange (Sweden) launch base and in equatorial region above the Teresina (Brazil) during easterly and westerly Quasibiennal Oscillation phase. We performed systematic comparisons between wind measurements and ERA—interim reanalysis from ECMWF (European Centre for Medium-Range Weather Forecasts) and present the vertical profile of biases for both wind component in winter at high latitude. The biases and the standard deviation obtained increase with altitude.

  8. High-accuracy identification of incident HIV-1 infections using a sequence clustering based diversity measure.

    PubMed

    Xia, Xia-Yu; Ge, Meng; Hsi, Jenny H; He, Xiang; Ruan, Yu-Hua; Wang, Zhi-Xin; Shao, Yi-Ming; Pan, Xian-Ming

    2014-01-01

    Accurate estimates of HIV-1 incidence are essential for monitoring epidemic trends and evaluating intervention efforts. However, the long asymptomatic stage of HIV-1 infection makes it difficult to effectively distinguish incident infections from chronic ones. Current incidence assays based on serology or viral sequence diversity are both still lacking in accuracy. In the present work, a sequence clustering based diversity (SCBD) assay was devised by utilizing the fact that viral sequences derived from each transmitted/founder (T/F) strain tend to cluster together at early stage, and that only the intra-cluster diversity is correlated with the time since HIV-1 infection. The dot-matrix pairwise alignment was used to eliminate the disproportional impact of insertion/deletions (indels) and recombination events, and so was the proportion of clusterable sequences (Pc) as an index to identify late chronic infections with declined viral genetic diversity. Tested on a dataset containing 398 incident and 163 chronic infection cases collected from the Los Alamos HIV database (last modified 2/8/2012), our SCBD method achieved 99.5% sensitivity and 98.8% specificity, with an overall accuracy of 99.3%. Further analysis and evaluation also suggested its performance was not affected by host factors such as the viral subtypes and transmission routes. The SCBD method demonstrated the potential of sequencing based techniques to become useful for identifying incident infections. Its use may be most advantageous for settings with low to moderate incidence relative to available resources. The online service is available at http://www.bioinfo.tsinghua.edu.cn:8080/SCBD/index.jsp. PMID:24925130

  9. High Accuracy Ultraviolet Index of Refraction Measurements Using a Fourier Transform Spectrometer

    PubMed Central

    Gupta, Rajeev; Kaplan, Simon G.

    2003-01-01

    We have constructed a new facility at the National Institute of Standards and Technology (NIST) to measure the index of refraction of transmissive materials in the wavelength range from the visible to the vacuum ultraviolet. An etalon of the material is illuminated with synchrotron radiation, and the interference fringes in the transmittance spectrum are measured using a Fourier transform spectrometer. The refractive index of calcium fluoride, CaF2, has been measured from 600 nm to 175 nm and the resulting values agree with a traditional goniometric measurement to within 1 × 10−5. The uncertainty in the index values is currently limited by the uncertainty in the thickness measurement of the etalon.

  10. High-Accuracy Measurement of the Differential Scalar Polarizability of a Sr+88 Clock Using the Time-Dilation Effect

    NASA Astrophysics Data System (ADS)

    Dubé, Pierre; Madej, Alan A.; Tibbo, Maria; Bernard, John E.

    2014-05-01

    We report a high-accuracy measurement of the differential static scalar polarizability Δα0 of the 5sS1/22-4dD5/22 transition of the Sr+88 ion. The high accuracy is obtained by comparing the micromotion-induced positive scalar Stark shift to the negative time-dilation shift. Measurement of the trap drive frequency where these shifts cancel is used to determine Δα0 without the need to determine the electric field. Δα0 is a critical parameter for the operation of frequency standards as it determines the blackbody radiation frequency shift coefficient, the largest source of uncertainty in the Sr+88 ion clock. The measured value of Δα0 is -4.7938(71)×10-40 J m2/V2. Taking into account the dynamic correction, the blackbody shift at 300 K is 0.247 99(37) Hz. The contribution of the blackbody shift coefficient to the uncertainty of the ion standard has been reduced by a factor of 24, from 2×10-17 to 8.3×10-19. The revised total uncertainty of our reference standard is 1.2×10-17, limited by the blackbody field evaluation. An additional benefit of the low uncertainty of Δα0 is the ability to suppress, by a factor of about 200, the net micromotion frequency shifts.

  11. High-accuracy measurement of the differential scalar polarizability of a 88Sr+ clock using the time-dilation effect.

    PubMed

    Dubé, Pierre; Madej, Alan A; Tibbo, Maria; Bernard, John E

    2014-05-01

    We report a high-accuracy measurement of the differential static scalar polarizability Δα(0) of the 5s(2)S(1/2)-4d(2)D(5/2) transition of the (88)Sr(+) ion. The high accuracy is obtained by comparing the micromotion-induced positive scalar Stark shift to the negative time-dilation shift. Measurement of the trap drive frequency where these shifts cancel is used to determine Δα(0) without the need to determine the electric field. Δα(0) is a critical parameter for the operation of frequency standards as it determines the blackbody radiation frequency shift coefficient, the largest source of uncertainty in the (88)Sr(+) ion clock. The measured value of Δα(0) is -4.7938(71) × 10(-40) J m(2)/V(2). Taking into account the dynamic correction, the blackbody shift at 300 K is 0.247,99(37) Hz. The contribution of the blackbody shift coefficient to the uncertainty of the ion standard has been reduced by a factor of 24, from 2 × 10(-17) to 8.3 × 10(-19). The revised total uncertainty of our reference standard is 1.2 × 10(-17), limited by the blackbody field evaluation. An additional benefit of the low uncertainty of Δα(0) is the ability to suppress, by a factor of about 200, the net micromotion frequency shifts. PMID:24836242

  12. High-Accuracy Surface Figure Measurement of Silicon Mirrors at 80 K

    NASA Technical Reports Server (NTRS)

    Blake, Peter; Mink, Ronald G.; Chambers, John; Davila, Pamela; Robinson, F. David

    2004-01-01

    This report describes the equipment, experimental methods, and first results at a new facility for interferometric measurement of cryogenically-cooled spherical mirrors at the Goddard Space Flight Center Optics Branch. The procedure, using standard phase-shifting interferometry, has an standard combined uncertainty of 3.6 nm rms in its representation of the two-dimensional surface figure error at 80, and an uncertainty of plus or minus 1 nm in the rms statistic itself. The first mirror tested was a concave spherical silicon foam-core mirror, with a clear aperture of 120 mm. The optic surface was measured at room temperature using standard absolute techniques; and then the change in surface figure error from room temperature to 80 K was measured. The mirror was cooled within a cryostat. and its surface figure error measured through a fused-silica window. The facility and techniques will be used to measure the surface figure error at 20K of prototype lightweight silicon carbide and Cesic mirrors developed by Galileo Avionica (Italy) for the European Space Agency (ESA).

  13. High-accuracy simultaneous measurement of particle size and location using interferometric out-of-focus imaging.

    PubMed

    Qieni, Lu; Kan, Han; Baozhen, Ge; Xiang, Wang

    2016-07-25

    A method based on unidirectional gradient-matched algorithm and Fourier transform technique is proposed to simultaneously extract the location and the number of fringes/fringe spacing of a particle interferogram. The position coordinate (x,y) of a particle can be determined with high accuracy because of the elimination of the fringe within the particle fringe pattern. Furthermore, the method can be employed to achieve sub-pixel frequency extraction when combined with an improved Rife algorithm. The performance of the method has been verified by numerical simulations and experimental measurements. The results suggest that the method presented here is highly beneficial to applications such as spray, in accurately measuring both the particle size and its location. PMID:27464108

  14. High accuracy time transfer synchronization

    NASA Technical Reports Server (NTRS)

    Wheeler, Paul J.; Koppang, Paul A.; Chalmers, David; Davis, Angela; Kubik, Anthony; Powell, William M.

    1995-01-01

    In July 1994, the U.S. Naval Observatory (USNO) Time Service System Engineering Division conducted a field test to establish a baseline accuracy for two-way satellite time transfer synchronization. Three Hewlett-Packard model 5071 high performance cesium frequency standards were transported from the USNO in Washington, DC to Los Angeles, California in the USNO's mobile earth station. Two-Way Satellite Time Transfer links between the mobile earth station and the USNO were conducted each day of the trip, using the Naval Research Laboratory(NRL) designed spread spectrum modem, built by Allen Osborne Associates(AOA). A Motorola six channel GPS receiver was used to track the location and altitude of the mobile earth station and to provide coordinates for calculating Sagnac corrections for the two-way measurements, and relativistic corrections for the cesium clocks. This paper will discuss the trip, the measurement systems used and the results from the data collected. We will show the accuracy of using two-way satellite time transfer for synchronization and the performance of the three HP 5071 cesium clocks in an operational environment.

  15. A Time Projection Chamber for High Accuracy and Precision Fission Cross-Section Measurements

    SciTech Connect

    T. Hill; K. Jewell; M. Heffner; D. Carter; M. Cunningham; V. Riot; J. Ruz; S. Sangiorgio; B. Seilhan; L. Snyder; D. M. Asner; S. Stave; G. Tatishvili; L. Wood; R. G. Baker; J. L. Klay; R. Kudo; S. Barrett; J. King; M. Leonard; W. Loveland; L. Yao; C. Brune; S. Grimes; N. Kornilov; T. N. Massey; J. Bundgaard; D. L. Duke; U. Greife; U. Hager; E. Burgett; J. Deaven; V. Kleinrath; C. McGrath; B. Wendt; N. Hertel; D. Isenhower; N. Pickle; H. Qu; S. Sharma; R. T. Thornton; D. Tovwell; R. S. Towell; S.

    2014-09-01

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4p acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  16. Method for high-accuracy reflectance measurements in the 2.5-microm region.

    PubMed

    Richter, Rudolf; Müller, Andreas

    2003-02-20

    Reflectance measurement with spectroradiometers in the solar wavelength region (0.4-2.5 microm) are frequently conducted in the laboratory or in the field to characterize surface materials of artificial and natural targets. The spectral surface reflectance is calculated as the ratio of the signals obtained over the target surface and a reference panel, yielding a relative reflectance value. If the reflectance of the reference panel is known, the absolute target reflectance can be computed. This standard measurement technique assumes that the signal at the radiometer is due completely to reflected target and reference radiation. However, for field measurements in the 2.4-2.5-microm region with the Sun as the illumination source, the emitted thermal radiation is not a negligible part of the signal even at ambient temperatures, because the atmospheric transmittance, and thus the solar illumination level, is small in the atmospheric absorption regions. A new method is proposed that calculates reflectance values in the 2.4-2.5-microm region while it accounts for the reference panel reflectance and the emitted radiation. This technique needs instruments with noise-equivalent radiances of 2 orders of magnitude below currently commercially available instruments and requires measurement of the surface temperatures of target and reference. If the reference panel reflectance and temperature effects are neglected, the standard method yields reflectance errors up to 0.08 and 0.15 units for 7- and 2-nm bandwidth instruments, respectively. For the new method the corresponding errors can be reduced to approximately 0.01 units for the surface temperature range of 20-35 degrees C. PMID:12617226

  17. High-accuracy mass measurements of neutron-rich Kr isotopes

    SciTech Connect

    Delahaye, P.; Kellerbauer, A.; Audi, G.; Lunney, D.; Blaum, K.; George, S.; Carrel, F.; Herfurth, F.; Yazidjian, C.; Herlert, A.; Schweikhard, L.; Kluge, H.-J.

    2006-09-15

    The atomic masses of the neutron-rich krypton isotopes {sup 84,86-95}Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes {sup 94}Kr and {sup 95}Kr were measured for the first time. The masses of the radioactive nuclides {sup 89}Kr and {sup 91}Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.

  18. Broadband fully automated digitally assisted coaxial bridge for high accuracy impedance ratio measurements

    NASA Astrophysics Data System (ADS)

    Overney, Frédéric; Lüönd, Felix; Jeanneret, Blaise

    2016-06-01

    This paper describes the principle of a new fully automated digitally assisted coaxial bridge having a large bandwidth ranging from 60 Hz to 50 kHz. The performance of the bridge is evaluated making 1:1 comparisons between calculable ac resistors. The agreement between the calculated and the measured frequency dependence of the resistors is better than 5\\cdot {{10}-8} at frequencies up to 5 kHz, better than 1\\cdot {{10}-7} up to 20 kHz and better than 0.8\\cdot {{10}-6} up to 50 kHz. This bridge is particularly well suited to investigate the ac transport properties of graphene in the quantum Hall regime.

  19. Capillary LC Coupled with High-Mass Measurement Accuracy Mass Spectrometry for Metabolic Profiling

    SciTech Connect

    Ding, Jie; Sorensen, Christina M.; Zhang, Qibin; Jiang, Hongliang; Jaitly, Navdeep; Livesay, Eric A.; Shen, Yufeng; Smith, Richard D.; Metz, Thomas O.

    2007-08-15

    We have developed an efficient and robust high-pressure capillary LC-MS method for the identification of large numbers of metabolites in biological samples using both positive and negative ESI modes. Initial efforts focused on optimizing the separations conditions for metabolite extracts using various LC stationary phases in conjunction with multiple mobile phase systems, as applied to the separation of 45 metabolite standards. The optimal mobile and stationary phases of those tested were determined experimentally (in terms of peak shapes, theoretical plates, retention of small, polar compounds, etc.), and both linear and exponential gradients were applied in the study of metabolite extracts from the cyanobacterium Cyanothece sp. ATCC 51142. Finally, an automated dual-capillary LC system was constructed and evaluated for the effectiveness and reproducibility of the chromatographic separations using the above samples. When coupled with a commercial LTQ-Orbitrap MS, ~900 features were reproducibly detected from Cyanothece sp. ATCC 51142 metabolite extracts. In addition, 12 compounds were tentatively identified, based on accurate mass, isotopic distribution, and MS/MS information.

  20. High accuracy mass measurement of peptides with internal calibration using a dual electrospray ionization sprayer system for protein identification.

    PubMed

    Zhou, Feng; Shui, Wenqing; Lu, Yu; Yang, Pengyuan; Guo, Yinlong

    2002-01-01

    A dual-ESI-sprayer system was constructed and applied to achieve high accuracy of peptide mass measurement for protein identification by means of peptide mapping. Sample was introduced in one sprayer, and reference in the other, thus making internal calibration possible greatly enhancing the mass accuracy. Several samples were utilized to evaluate the reliability of this dual-ESI-sprayer system. The range of mass errors was 0.16-5.37 ppm. The peptide masses of tryptic digests of myoglobin (horse) were measured by the HPLC/dual-ESI-MS system, with mass deviations ranging from 0.01-7.67 ppm, and about 75% mass deviations below 5 ppm with 40% below 1[?]ppm. These peptide masses were utilized to perform database searching for protein identification, and compared to results obtained by external calibration. This comparison showed that the internal calibration provides a more reliable method of protein identification, with a much smaller number of required peptides for matching, and with less CPU time consumed for database searching. PMID:11870887

  1. Research on high-accuracy two-dimensional digital image correlation hardware measurement systems used in the engineering practice

    NASA Astrophysics Data System (ADS)

    Chen, Guang; Ding, Keqin; Feng, Qibo

    2014-11-01

    Digital image correlation (DIC) method is a rapid development of photomechanics technology. The basic principle of the method is calculated the correlation between before and after deformation of the specimen surface speckle images, which is used to determine displacement and deformation. DIC measurement system includes hardware and software system. The former is the speckle image acquisition system, the latter are speckle image analysis algorithm and implementation procedures. Because the software analysis algorithm can achieve sub-pixel accuracy or even more, most of scholars have focused on the speckle image analysis algorithms. The system performance caused by the composition of hardware system has been less introduced. The hardware system mainly included the camera, lenses, lighting and other components. If hardware system is not perfect and stable, it will bring hundreds or even thousands of micro strain measurement error. These unfavorable factors make 2D-DIC inaccurate in small deformation tests. To some extent, it limits the application of 2D-DIC in the engineering practice. This paper analyzed that the various components of DIC hardware system impacted on the system performance, It was given that how to reasonably select the various components in the typical cases, as well as involved that the selection of 2D-DIC measurement system is applied to the actual engineering measurements in high temperature environment. These can provide support that 2D-DIC measurement system is better applied to the engineering practice.

  2. High accuracy broadband infrared spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Krishnaswamy, Venkataramanan

    Mueller matrix spectroscopy or Spectropolarimetry combines conventional spectroscopy with polarimetry, providing more information than can be gleaned from spectroscopy alone. Experimental studies on infrared polarization properties of materials covering a broad spectral range have been scarce due to the lack of available instrumentation. This dissertation aims to fill the gap by the design, development, calibration and testing of a broadband Fourier Transform Infra-Red (FT-IR) spectropolarimeter. The instrument operates over the 3-12 mum waveband and offers better overall accuracy compared to the previous generation instruments. Accurate calibration of a broadband spectropolarimeter is a non-trivial task due to the inherent complexity of the measurement process. An improved calibration technique is proposed for the spectropolarimeter and numerical simulations are conducted to study the effectiveness of the proposed technique. Insights into the geometrical structure of the polarimetric measurement matrix is provided to aid further research towards global optimization of Mueller matrix polarimeters. A high performance infrared wire-grid polarizer is characterized using the spectropolarimeter. Mueller matrix spectrum measurements on Penicillin and pine pollen are also presented.

  3. High-accuracy diagnostic tool for electron cloud observation in the LHC based on synchronous phase measurements

    NASA Astrophysics Data System (ADS)

    Esteban Müller, J. F.; Baudrenghien, P.; Mastoridis, T.; Shaposhnikova, E.; Valuch, D.

    2015-11-01

    Electron cloud effects, which include heat load in the cryogenic system, pressure rise, and beam instabilities, are among the main intensity limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was proposed and developed to monitor the e-cloud activity and it has already been used successfully during the LHC run 1 (2010-2012) and it is being intensively used in operation during the start of the LHC run 2 (2015-2018). It is based on the fact that the power loss of each bunch due to e-cloud can be estimated using bunch-by-bunch measurement of the synchronous phase. The measurements were done using the existing beam phase module of the low-level rf control system. In order to achieve the very high accuracy required, corrections for reflection in the cables and for systematic errors need to be applied followed by a post-processing of the measurements. Results clearly show the e-cloud buildup along the bunch trains and its time evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield. The total beam power loss can be computed as a sum of the contributions from all bunches and compared with the heat load deposited in the cryogenic system.

  4. High precision and high accuracy isotopic measurement of uranium using lead and thorium calibration solutions by inductively coupled plasma-multiple collector-mass spectrometry

    SciTech Connect

    Bowen, I.; Walder, A.J.; Hodgson, T.; Parrish, R.R. |

    1998-12-31

    A novel method for the high accuracy and high precision measurement of uranium isotopic composition by Inductively Coupled Plasma-Multiple Collector-Mass Spectrometry is discussed. Uranium isotopic samples are spiked with either thorium or lead for use as internal calibration reference materials. This method eliminates the necessity to periodically measure uranium standards to correct for changing mass bias when samples are measured over long time periods. This technique has generated among the highest levels of analytical precision on both the major and minor isotopes of uranium. Sample throughput has also been demonstrated to exceed Thermal Ionization Mass Spectrometry by a factor of four to five.

  5. Improved accuracy of cortical bone mineralization measured by polychromatic microcomputed tomography using a novel high mineral density composite calibration phantom

    SciTech Connect

    Deuerling, Justin M.; Rudy, David J.; Niebur, Glen L.; Roeder, Ryan K.

    2010-09-15

    Purpose: Microcomputed tomography (micro-CT) is increasingly used as a nondestructive alternative to ashing for measuring bone mineral content. Phantoms are utilized to calibrate the measured x-ray attenuation to discrete levels of mineral density, typically including levels up to 1000 mg HA/cm{sup 3}, which encompasses levels of bone mineral density (BMD) observed in trabecular bone. However, levels of BMD observed in cortical bone and levels of tissue mineral density (TMD) in both cortical and trabecular bone typically exceed 1000 mg HA/cm{sup 3}, requiring extrapolation of the calibration regression, which may result in error. Therefore, the objectives of this study were to investigate (1) the relationship between x-ray attenuation and an expanded range of hydroxyapatite (HA) density in a less attenuating polymer matrix and (2) the effects of the calibration on the accuracy of subsequent measurements of mineralization in human cortical bone specimens. Methods: A novel HA-polymer composite phantom was prepared comprising a less attenuating polymer phase (polyethylene) and an expanded range of HA density (0-1860 mg HA/cm{sup 3}) inclusive of characteristic levels of BMD in cortical bone or TMD in cortical and trabecular bone. The BMD and TMD of cortical bone specimens measured using the new HA-polymer calibration phantom were compared to measurements using a conventional HA-polymer phantom comprising 0-800 mg HA/cm{sup 3} and the corresponding ash density measurements on the same specimens. Results: The HA-polymer composite phantom exhibited a nonlinear relationship between x-ray attenuation and HA density, rather than the linear relationship typically employed a priori, and obviated the need for extrapolation, when calibrating the measured x-ray attenuation to high levels of mineral density. The BMD and TMD of cortical bone specimens measured using the conventional phantom was significantly lower than the measured ash density by 19% (p<0.001, ANCOVA) and 33% (p<0

  6. High accuracy calibration of the fiber spectroradiometer

    NASA Astrophysics Data System (ADS)

    Wu, Zhifeng; Dai, Caihong; Wang, Yanfei; Chen, Binhua

    2014-11-01

    Comparing to the big-size scanning spectroradiometer, the compact and convenient fiber spectroradiometer is widely used in various kinds of fields, such as the remote sensing, aerospace monitoring, and solar irradiance measurement. High accuracy calibration should be made before the use, which involves the wavelength accuracy, the background environment noise, the nonlinear effect, the bandwidth, the stray light and et al. The wavelength lamp and tungsten lamp are frequently used to calibration the fiber spectroradiometer. The wavelength difference can be easily reduced through the software or calculation. However, the nonlinear effect and the bandwidth always can affect the measurement accuracy significantly.

  7. High angular accuracy manufacture method of micro v-grooves based on tool alignment by on-machine measurement.

    PubMed

    Zhang, Xiaodong; Jiang, Lili; Zeng, Zhen; Fang, Fengzhou; Liu, Xianlei

    2015-10-19

    Micro v-groove has found wide applications in optical areas as one of the most important structures. However, its performance is significantly affected by its angular geometry accuracy. The diamond cutting has been commonly used as the fabrication method of micro v-groove, but it is still difficult to guarantee the cutting tool angle, which is limited by the measurement accuracy in the manufacture and mounting of the diamond tool. A cutting tool alignment method based on the on-machine measurement is proposed to improve the fabricated quality of the v-groove angle. An on-machine probe is employed to scan the v-groove geometrical deviation precisely. The system errors model, data processing algorithm and tool alignment methods are analyzed in details. Experimental results show that the measurement standard deviation within 0.01° can be achieved. Retro-reflection mirrors are fabricated and measured finally by the proposed method for verification. PMID:26480443

  8. First results using a new technology for measuring masses of very short-lived nuclides with very high accuracy: The MISTRAL program at ISOLDE

    SciTech Connect

    Monsanglant, C.; Audi, G.; Conreur, G.; Cousin, R.; Doubre, H.; Jacotin, M.; Henry, S.; Kepinski, J.-F.; Lunney, D.; Saint Simon, M. de; Thibault, C.; Toader, C.; Bollen, G.; Lebee, G.; Scheidenberger, C.; Borcea, C.; Duma, M.; Kluge, H.-J.; Le Scornet, G.

    1999-11-16

    MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na, Mg, Al, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

  9. Distortion measurement of antennas under space simulation conditions with high accuracy and high resolution by means of holography

    NASA Technical Reports Server (NTRS)

    Frey, H. U.

    1984-01-01

    The use of laser holography for measuring the distortion of antennas under space simulation conditions is described. The subject is the so-called double exposure procedure which allows to measure the distortion in the order of 1 to 30/micrometers + or - 0.5 per hologramme of an area of 4 m diameter max. The method of holography takes into account the constraints of the space simulation facility. The test method, the test set up and the constraints by the space simulation facility are described. The results of the performed tests are presented and compared with the theoretical predictions. The test on the K-Band Antenna e.g., showed a distortion of approximately 140/micrometers + or - 5/micrometers measured during the cool down from -10 C to -120 C.

  10. Measuring Diagnoses: ICD Code Accuracy

    PubMed Central

    O'Malley, Kimberly J; Cook, Karon F; Price, Matt D; Wildes, Kimberly Raiford; Hurdle, John F; Ashton, Carol M

    2005-01-01

    Objective To examine potential sources of errors at each step of the described inpatient International Classification of Diseases (ICD) coding process. Data Sources/Study Setting The use of disease codes from the ICD has expanded from classifying morbidity and mortality information for statistical purposes to diverse sets of applications in research, health care policy, and health care finance. By describing a brief history of ICD coding, detailing the process for assigning codes, identifying where errors can be introduced into the process, and reviewing methods for examining code accuracy, we help code users more systematically evaluate code accuracy for their particular applications. Study Design/Methods We summarize the inpatient ICD diagnostic coding process from patient admission to diagnostic code assignment. We examine potential sources of errors at each step and offer code users a tool for systematically evaluating code accuracy. Principle Findings Main error sources along the “patient trajectory” include amount and quality of information at admission, communication among patients and providers, the clinician's knowledge and experience with the illness, and the clinician's attention to detail. Main error sources along the “paper trail” include variance in the electronic and written records, coder training and experience, facility quality-control efforts, and unintentional and intentional coder errors, such as misspecification, unbundling, and upcoding. Conclusions By clearly specifying the code assignment process and heightening their awareness of potential error sources, code users can better evaluate the applicability and limitations of codes for their particular situations. ICD codes can then be used in the most appropriate ways. PMID:16178999

  11. Accuracy of the river discharge measurement

    NASA Astrophysics Data System (ADS)

    Chung Yang, Han

    2013-04-01

    Discharge values recorded for water conservancy and hydrological analysis is a very important work. Flood control projects, watershed remediation and river environmental planning projects quite need the discharge measurement data. In Taiwan, we have 129 rivers, in accordance with the watershed situation, economic development and other factors, divided into 24 major rivers, 29 minor rivers and 79 ordinary rivers. If each river needs to measure and record these discharge values, it will be enormous work. In addition, the characteristics of Taiwan's rivers contain steep slope, flow rapidly and sediment concentration higher, so it really encounters some difficulties in high flow measurement. When the flood hazards come, to seek a solution for reducing the time, manpower and material resources in river discharge measurement is very important. In this study, the river discharge measurement accuracy is used to determine the tolerance percentage to reduce the number of vertical velocity measurements, thereby reducing the time, manpower and material resources in the river discharge measurement. The velocity data sources used in this study form Yang (1998). Yang (1998) used the Fiber-optic Laser Doppler Velocimetery (FLDV) to obtain different velocity data under different experimental conditions. In this study, we use these data to calculate the mean velocity of each vertical line by three different velocity profile formula (that is, the law of the wall, Chiu's theory, Hu's theory), and then multiplied by each sub-area to obtain the discharge measurement values and compared with the true values (obtained by the direct integration mode) to obtain the accuracy of discharge. The research results show that the discharge measurement values obtained by Chiu's theory are closer to the true value, while the maximum error is the law of the wall. The main reason is that the law of the wall can't describe the maximum velocity occurred in underwater. In addition, the results also show

  12. Low-level measuring techniques for neutrons: High accuracy neutron source strength determination and fluence rate measurement at an underground laboratory

    SciTech Connect

    Zimbal, Andreas; Reginatto, Marcel; Schuhmacher, Helmut; Wiegel, Burkhard; Degering, Detlev; Zuber, Kai

    2013-08-08

    We report on measuring techniques for neutrons that have been developed at the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. PTB has characterized radioactive sources used in the BOREXINO and XENON100 experiments. For the BOREXINO experiment, a {sup 228}Th gamma radiation source was required which would not emit more than 10 neutrons per second. The determination of the neutron emission rate of this specially designed {sup 228}Th source was challenging due to the low neutron emission rate and because the ratio of neutron to gamma radiation was expected to be extremely low, of the order of 10{sup −6}. For the XENON100 detector, PTB carried out a high accuracy measurement of the neutron emission rate of an AmBe source. PTB has also done measurements in underground laboratories. A two month measurement campaign with a set of {sup 3}He-filled proportional counters was carried out in PTB's former UDO underground laboratory at the Asse salt mine. The aim of the campaign was to determine the intrinsic background of detectors, which is needed for the analysis of data taken in lowintensity neutron fields. At a later time, PTB did a preliminary measurement of the neutron fluence rate at the underground laboratory Felsenkeller operated by VKTA. By taking into account data from UDO, Felsenkeller, and detector calibrations made at the PTB facility, it was possible to estimate the neutron fluence rate at the Felsenkeller underground laboratory.

  13. The Cryogenic, High-Accuracy, Refraction Measuring System (CHARMS): A New Facility for Cryogenic Infrared through Vacuum Far-Ultraviolet Refractive Index Measurements

    NASA Technical Reports Server (NTRS)

    Frey, Bradley J.; Leviton, Douglas B.

    2004-01-01

    The optical designs of future NASA infrared (IR) missions and instruments, such as the James Webb Space Telescope's (JWST) Near-Mixed Camera (NIRCam), will rely on accurate knowledge of the index of refraction of various IR optical materials at cryogenic temperatures. To meet this need, we have developed a Cryogenic, High-Accuracy Refraction Measuring System (CHARMS). In this paper we discuss the completion of the design and construction of CHARMS as well as the engineering details that constrained the final design and hardware implementation. In addition, we will present our first light, cryogenic, IR index of refraction data for LiF, BaF2, and CaF2, and compare our results to previously published data for these materials.

  14. Measuring the Accuracy of Diagnostic Systems.

    ERIC Educational Resources Information Center

    Swets, John A.

    1988-01-01

    Discusses the relative operating characteristic analysis of signal detection theory as a measure of diagnostic accuracy. Reports representative values of this measure in several fields. Compares how problems in these fields are handled. (CW)

  15. Discrimination in measures of knowledge monitoring accuracy

    PubMed Central

    Was, Christopher A.

    2014-01-01

    Knowledge monitoring predicts academic outcomes in many contexts. However, measures of knowledge monitoring accuracy are often incomplete. In the current study, a measure of students’ ability to discriminate known from unknown information as a component of knowledge monitoring was considered. Undergraduate students’ knowledge monitoring accuracy was assessed and used to predict final exam scores in a specific course. It was found that gamma, a measure commonly used as the measure of knowledge monitoring accuracy, accounted for a small, but significant amount of variance in academic performance whereas the discrimination and bias indexes combined to account for a greater amount of variance in academic performance. PMID:25339979

  16. Anatomy-aware measurement of segmentation accuracy

    NASA Astrophysics Data System (ADS)

    Tizhoosh, H. R.; Othman, A. A.

    2016-03-01

    Quantifying the accuracy of segmentation and manual delineation of organs, tissue types and tumors in medical images is a necessary measurement that suffers from multiple problems. One major shortcoming of all accuracy measures is that they neglect the anatomical significance or relevance of different zones within a given segment. Hence, existing accuracy metrics measure the overlap of a given segment with a ground-truth without any anatomical discrimination inside the segment. For instance, if we understand the rectal wall or urethral sphincter as anatomical zones, then current accuracy measures ignore their significance when they are applied to assess the quality of the prostate gland segments. In this paper, we propose an anatomy-aware measurement scheme for segmentation accuracy of medical images. The idea is to create a "master gold" based on a consensus shape containing not just the outline of the segment but also the outlines of the internal zones if existent or relevant. To apply this new approach to accuracy measurement, we introduce the anatomy-aware extensions of both Dice coefficient and Jaccard index and investigate their effect using 500 synthetic prostate ultrasound images with 20 different segments for each image. We show that through anatomy-sensitive calculation of segmentation accuracy, namely by considering relevant anatomical zones, not only the measurement of individual users can change but also the ranking of users' segmentation skills may require reordering.

  17. First Results Using a New Technology for Measuring Masses of Very Short-Lived Nuclides with Very High Accuracy: the MISTRAL Program at ISOLDE

    SciTech Connect

    C. Monsanglant; C. Toader; G. Audi; G. Bollen; C. Borcea; G. Conreur; R. Cousin; H. Doubre; M. Duma; M. Jacotin; S. Henry; J.-F. Kepinski; H.-J. Kluge; G. Lebee; G. Le Scornet; D. Lunney; M. de Saint Simon; C. Scheidenberger; C. Thibault

    1999-12-31

    MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na{clubsuit}, Mg, Al{clubsuit}, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

  18. Ultrastable low-noise current amplifier: A novel device for measuring small electric currents with high accuracy

    SciTech Connect

    Drung, D.; Krause, C.; Becker, U.; Scherer, H.; Ahlers, F. J.

    2015-02-15

    An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MΩ reference resistor or, optionally, an external standard resistor. The ULCA’s transfer coefficient is highly stable versus time, temperature, and current amplitude within the full dynamic range of ±5 nA. The low noise level of 2.4 fA/√Hz helps to keep averaging times short at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Within one week after calibration, the uncertainty contribution from short-term fluctuations and drift of the transresistance is about 0.1 parts per million (ppm). The long-term drift is typically 5 ppm/yr. A high-accuracy variant is available that shows improved stability of the input gain at the expense of a higher noise level of 7.5 fA/√Hz. The ULCA also allows the traceable generation of small electric currents or the calibration of high-ohmic resistors.

  19. Ultrastable low-noise current amplifier: a novel device for measuring small electric currents with high accuracy.

    PubMed

    Drung, D; Krause, C; Becker, U; Scherer, H; Ahlers, F J

    2015-02-01

    An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MΩ reference resistor or, optionally, an external standard resistor. The ULCA's transfer coefficient is highly stable versus time, temperature, and current amplitude within the full dynamic range of ±5 nA. The low noise level of 2.4 fA/√Hz helps to keep averaging times short at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Within one week after calibration, the uncertainty contribution from short-term fluctuations and drift of the transresistance is about 0.1 parts per million (ppm). The long-term drift is typically 5 ppm/yr. A high-accuracy variant is available that shows improved stability of the input gain at the expense of a higher noise level of 7.5 fA/√Hz. The ULCA also allows the traceable generation of small electric currents or the calibration of high-ohmic resistors. PMID:25725866

  20. Ultrastable low-noise current amplifier: A novel device for measuring small electric currents with high accuracy

    NASA Astrophysics Data System (ADS)

    Drung, D.; Krause, C.; Becker, U.; Scherer, H.; Ahlers, F. J.

    2015-02-01

    An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MΩ reference resistor or, optionally, an external standard resistor. The ULCA's transfer coefficient is highly stable versus time, temperature, and current amplitude within the full dynamic range of ±5 nA. The low noise level of 2.4 fA/√Hz helps to keep averaging times short at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Within one week after calibration, the uncertainty contribution from short-term fluctuations and drift of the transresistance is about 0.1 parts per million (ppm). The long-term drift is typically 5 ppm/yr. A high-accuracy variant is available that shows improved stability of the input gain at the expense of a higher noise level of 7.5 fA/√Hz. The ULCA also allows the traceable generation of small electric currents or the calibration of high-ohmic resistors.

  1. A high-accuracy roundness measurement for cylindrical components by a morphological filter considering eccentricity, probe offset, tip head radius and tilt error

    NASA Astrophysics Data System (ADS)

    Sun, Chuanzhi; Wang, Lei; Tan, Jiubin; Zhao, Bo; Zhou, Tong; Kuang, Ye

    2016-08-01

    A morphological filter is proposed to obtain a high-accuracy roundness measurement based on the four-parameter roundness measurement model, which takes into account eccentricity, probe offset, probe tip head radius and tilt error. This paper analyses the sample angle deviations caused by the four systematic errors to design a morphological filter based on the distribution of the sample angle. The effectiveness of the proposed method is verified through simulations and experiments performed with a roundness measuring machine. Compared to the morphological filter with the uniform sample angle, the accuracy of the roundness measurement can be increased by approximately 0.09 μm using the morphological filter with a non-uniform sample angle based on the four-parameter roundness measurement model, when eccentricity is above 16 μm, probe offset is approximately 1000 μm, tilt error is approximately 1″, the probe tip head radius is 1 mm and the cylindrical component radius is approximately 37 mm. The accuracy and reliability of roundness measurements are improved by using the proposed method for cylindrical components with a small radius, especially if the eccentricity and probe offset are large, and the tilt error and probe tip head radius are small. The proposed morphological filter method can be used for precision and ultra-precision roundness measurements, especially for functional assessments of roundness profiles.

  2. Measuring Tracking Accuracy of CCD Imagers

    NASA Technical Reports Server (NTRS)

    Stanton, R. H.; Dennison, E. W.

    1985-01-01

    Tracking accuracy and resolution of charge-coupled device (CCD) imaging arrays measured by instrument originally developed for measuring performance of star-tracking telescope. Operates by projecting one or more artifical star images on surface of CCD array, moving stars in controlled patterns, and comparing star locations computed from CCD outputs with those calculated from step coordinates of micropositioner.

  3. Copper disk pyrheliometer of high accuracy

    SciTech Connect

    Hsieh, C.K.; Wang, X.A.

    1983-01-01

    A copper disk pyrheliometer has been designed and constructed that utilizes a new methodology to measure solar radiation. By operating the shutter of the instrument and measuring the heating and cooling rates of the sensor at the very moment when the sensor is at the same temperature, the solar radiation can be accurately determined with these rates. The method is highly accurate and is shown to be totally independent of the loss coefficient in the measurement. The pyrheliometer has been tested using a standard irradiance lamp in the laboratory. The uncertainty of the instrument is identified to be +- 0.61%. Field testing was also conducted by comparing data with that of a calibrated (Eppley) Normal Incidence Pyrheliometer. This paper spells out details of the construction and testing of the instrument; the analysis underlying the methodology was also covered in detail. Because of the high accuracy, the instrument is considered to be well suited for a bench standard for measurement of solar radiation.

  4. High accuracy thermal conductivity measurement of aqueous cryoprotective agents and semi-rigid biological tissues using a microfabricated thermal sensor

    PubMed Central

    Liang, Xin M.; Sekar, Praveen K.; Zhao, Gang; Zhou, Xiaoming; Shu, Zhiquan; Huang, Zhongping; Ding, Weiping; Zhang, Qingchuan; Gao, Dayong

    2015-01-01

    An improved thermal-needle approach for accurate and fast measurement of thermal conductivity of aqueous and soft biomaterials was developed using microfabricated thermal conductivity sensors. This microscopic measuring device was comprehensively characterized at temperatures from 0 °C to 40 °C. Despite the previous belief, system calibration constant was observed to be highly temperature-dependent. Dynamic thermal conductivity response during cooling (40 °C to –40 °C) was observed using the miniaturized single tip sensor for various concentrations of CPAs, i.e., glycerol, ethylene glycol and dimethyl sulfoxide. Chicken breast, chicken skin, porcine limb, and bovine liver were assayed to investigate the effect of anatomical heterogeneity on thermal conductivity using the arrayed multi-tip sensor at 20 °C. Experimental results revealed distinctive differences in localized thermal conductivity, which suggests the use of approximated or constant property values is expected to bring about results with largely inflated uncertainties when investigating bio-heat transfer mechanisms and/or performing sophisticated thermal modeling with complex biological tissues. Overall, the presented micro thermal sensor with automated data analysis algorithm is a promising approach for direct thermal conductivity measurement of aqueous solutions and soft biomaterials and is of great value to cryopreservation of tissues, hyperthermia or cryogenic, and other thermal-based clinical diagnostics and treatments. PMID:25993037

  5. High accuracy thermal conductivity measurement of aqueous cryoprotective agents and semi-rigid biological tissues using a microfabricated thermal sensor

    NASA Astrophysics Data System (ADS)

    Liang, Xin M.; Sekar, Praveen K.; Zhao, Gang; Zhou, Xiaoming; Shu, Zhiquan; Huang, Zhongping; Ding, Weiping; Zhang, Qingchuan; Gao, Dayong

    2015-05-01

    An improved thermal-needle approach for accurate and fast measurement of thermal conductivity of aqueous and soft biomaterials was developed using microfabricated thermal conductivity sensors. This microscopic measuring device was comprehensively characterized at temperatures from 0 °C to 40 °C. Despite the previous belief, system calibration constant was observed to be highly temperature-dependent. Dynamic thermal conductivity response during cooling (40 °C to -40 °C) was observed using the miniaturized single tip sensor for various concentrations of CPAs, i.e., glycerol, ethylene glycol and dimethyl sulfoxide. Chicken breast, chicken skin, porcine limb, and bovine liver were assayed to investigate the effect of anatomical heterogeneity on thermal conductivity using the arrayed multi-tip sensor at 20 °C. Experimental results revealed distinctive differences in localized thermal conductivity, which suggests the use of approximated or constant property values is expected to bring about results with largely inflated uncertainties when investigating bio-heat transfer mechanisms and/or performing sophisticated thermal modeling with complex biological tissues. Overall, the presented micro thermal sensor with automated data analysis algorithm is a promising approach for direct thermal conductivity measurement of aqueous solutions and soft biomaterials and is of great value to cryopreservation of tissues, hyperthermia or cryogenic, and other thermal-based clinical diagnostics and treatments.

  6. Inkjet Metrology: High-Accuracy Mass Measurements of Microdroplets Produced by a Drop-on-Demand Dispenser

    PubMed Central

    2009-01-01

    We describe gravimetric methods for measuring the mass of droplets generated by a drop-on-demand (DOD) microdispenser. Droplets are deposited, either continuously at a known frequency or as a burst of known number, into a cylinder positioned on a submicrogram balance. Mass measurements are acquired precisely by computer, and results are corrected for evaporation. Capabilities are demonstrated using isobutyl alcohol droplets. For ejection rates greater than 100 Hz, the repeatability of droplet mass measurements was 0.2%, while the combined relative standard uncertainty (uc) was 0.9%. When bursts of droplets were dispensed, the limit of quantitation was 72 μg (1490 droplets) with uc = 1.0%. Individual droplet size in a burst was evaluated by high-speed videography. Diameters were consistent from the tenth droplet onward, and the mass of an individual droplet was best estimated by the average droplet mass with a combined uncertainty of about 1%. Diameters of the first several droplets were anomalous, but their contribution was accounted for when dispensing bursts. Above the limits of quantitation, the gravimetric methods provided statistically equivalent results and permit detailed study of operational factors that influence droplet mass during dispensing, including the development of reliable microassays and standard materials using DOD technologies. PMID:19824716

  7. Measurement Accuracy Limitation Analysis on Synchrophasors

    SciTech Connect

    Zhao, Jiecheng; Zhan, Lingwei; Liu, Yilu; Qi, Hairong; Gracia, Jose R; Ewing, Paul D

    2015-01-01

    This paper analyzes the theoretical accuracy limitation of synchrophasors measurements on phase angle and frequency of the power grid. Factors that cause the measurement error are analyzed, including error sources in the instruments and in the power grid signal. Different scenarios of these factors are evaluated according to the normal operation status of power grid measurement. Based on the evaluation and simulation, the errors of phase angle and frequency caused by each factor are calculated and discussed.

  8. Improvement in Rayleigh Scattering Measurement Accuracy

    NASA Technical Reports Server (NTRS)

    Fagan, Amy F.; Clem, Michelle M.; Elam, Kristie A.

    2012-01-01

    Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous velocity, density, and temperature measurements. The Fabry-Perot interferometer or etalon is a commonly employed instrument for resolving the spectrum of molecular Rayleigh scattered light for the purpose of evaluating these flow properties. This paper investigates the use of an acousto-optic frequency shifting device to improve measurement accuracy in Rayleigh scattering experiments at the NASA Glenn Research Center. The frequency shifting device is used as a means of shifting the incident or reference laser frequency by 1100 MHz to avoid overlap of the Rayleigh and reference signal peaks in the interference pattern used to obtain the velocity, density, and temperature measurements, and also to calibrate the free spectral range of the Fabry-Perot etalon. The measurement accuracy improvement is evaluated by comparison of Rayleigh scattering measurements acquired with and without shifting of the reference signal frequency in a 10 mm diameter subsonic nozzle flow.

  9. High-accuracy 2D digital image correlation measurements using low-cost imaging lenses: implementation of a generalized compensation method

    NASA Astrophysics Data System (ADS)

    Pan, Bing; Yu, Liping; Wu, Dafang

    2014-02-01

    The ideal pinhole imaging model commonly assumed for an ordinary two-dimensional digital image correlation (2D-DIC) system is neither perfect nor stable because of the existence of small out-of-plane motion of the test sample surface that occurred after loading, small out-of-plane motion of the sensor target due to temperature variation of a camera and unavoidable geometric distortion of an imaging lens. In certain cases, these disadvantages can lead to significant errors in the measured displacements and strains. Although a high-quality bilateral telecentric lens has been strongly recommended to be used in the 2D-DIC system as an essential optical component to achieve high-accuracy measurement, it is not generally applicable due to its fixed field of view, limited depth of focus and high cost. To minimize the errors associated with the imperfectness and instability of a common 2D-DIC system using a low-cost imaging lens, a generalized compensation method using a non-deformable reference sample is proposed in this work. With the proposed method, the displacement of the reference sample rigidly attached behind the test sample is first measured using 2D-DIC, and then it is fitted using a parametric model. The fitted parametric model is then used to correct the displacements of the deformed sample to remove the influences of these unfavorable factors. The validity of the proposed compensation method is first verified using out-of-plane translation, out-of-plane rotation, in-plane translation tests and their combinations. Uniaxial tensile tests of an aluminum specimen were also performed to quantitatively examine the strain accuracy of the proposed compensation method. Experiments show that the proposed compensation method is an easy-to-implement yet effective technique for achieving high-accuracy deformation measurement using an ordinary 2D-DIC system.

  10. High current high accuracy IGBT pulse generator

    SciTech Connect

    Nesterov, V.V.; Donaldson, A.R.

    1995-05-01

    A solid state pulse generator capable of delivering high current triangular or trapezoidal pulses into an inductive load has been developed at SLAC. Energy stored in a capacitor bank of the pulse generator is switched to the load through a pair of insulated gate bipolar transistors (IGBT). The circuit can then recover the remaining energy and transfer it back to the capacitor bank without reversing the capacitor voltage. A third IGBT device is employed to control the initial charge to the capacitor bank, a command charging technique, and to compensate for pulse to pulse power losses. The rack mounted pulse generator contains a 525 {mu}F capacitor bank. It can deliver 500 A at 900V into inductive loads up to 3 mH. The current amplitude and discharge time are controlled to 0.02% accuracy by a precision controller through the SLAC central computer system. This pulse generator drives a series pair of extraction dipoles.

  11. Wind velocity measurement accuracy with highly stable 12 mJ/pulse high repetition rate CO2 laser master oscillator power amplifier

    NASA Technical Reports Server (NTRS)

    Bilbro, James W.; Johnson, Steven C.; Rothermel, Jeffry

    1987-01-01

    A coherent CO2 lidar operating in a master oscillator power amplifier configuration (MOPA) is described for both ground-based and airborne operation. Representative data taken from measurements against stationary targets in both the ground-based and airborne configurations are shown for the evaluation of the frequency stability of the system. Examples of data are also given which show the results of anomalous system operation. Overall results demonstrate that velocity measurements can be performed consistently to an accuracy of + or - 0.5 m/s and in some cases + or - 0.1 m/s.

  12. Accuracy of the blood pressure measurement.

    PubMed

    Rabbia, F; Del Colle, S; Testa, E; Naso, D; Veglio, F

    2006-08-01

    Blood pressure measurement is the cornerstone for the diagnosis, the treatment and the research on arterial hypertension, and all of the decisions about one of these single aspects may be dramatically influenced by the accuracy of the measurement. Over the past 20 years or so, the accuracy of the conventional Riva-Rocci/Korotkoff technique of blood pressure measurement has been questioned and efforts have been made to improve the technique with automated devices. In the same period, recognition of the phenomenon of white coat hypertension, whereby some individuals with an apparent increase in blood pressure have normal, or reduced, blood pressures when measurement is repeated away from the medical environment, has focused attention on methods of measurement that provide profiles of blood pressure behavior rather than relying on isolated measurements under circumstances that may in themselves influence the level of blood pressure recorded. These methodologies have included repeated measurements of blood pressure using the traditional technique, self-measurement of blood pressure in the home or work place, and ambulatory blood pressure measurement using innovative automated devices. The purpose of this review to serve as a source of practical information about the commonly used methods for blood pressure measurement: the traditional Riva-Rocci method and the automated methods. PMID:17016412

  13. Measurement of high-energy (10–60 keV) x-ray spectral line widths with eV accuracy

    SciTech Connect

    Seely, J. F. Feldman, U.; Glover, J. L.; Hudson, L. T.; Ralchenko, Y.; Henins, Albert; Pereira, N.; Di Stefano, C. A.; Kuranz, C. C.; Drake, R. P.; Chen, Hui; Williams, G. J.; Park, J.

    2014-11-15

    A high resolution crystal spectrometer utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the widths of emission lines in the 10–60 keV energy range with eV accuracy. The spectrometer achieves high spectral resolution by utilizing crystal planes with small lattice spacings (down to 2d = 0.099 nm), a large crystal bending radius and Rowland circle diameter (965 mm), and an image plate detector with high spatial resolution (60 μm in the case of the Fuji TR image plate). High resolution W L-shell and K-shell laboratory test spectra in the 10–60 keV range and Ho K-shell spectra near 47 keV recorded at the LLNL Titan laser facility are presented. The Ho K-shell spectra are the highest resolution hard x-ray spectra recorded from a solid target irradiated by a high-intensity laser.

  14. High accuracy electronic material level sensor

    DOEpatents

    McEwan, Thomas E.

    1997-01-01

    The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: 1) a high accuracy time base that is referenced to a quartz crystal, 2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, 3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or "ghost" reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%.

  15. High accuracy electronic material level sensor

    DOEpatents

    McEwan, T.E.

    1997-03-11

    The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: (1) a high accuracy time base that is referenced to a quartz crystal, (2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, (3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or ``ghost`` reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%. 4 figs.

  16. 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}.

  17. Development of a dual-sinker densimeter for high-accuracy fluid P-V-T measurements. Appendix A

    SciTech Connect

    McLinden, M.O.; Frederick, N.V.

    1993-08-01

    A dual-sinker densimeter to very accurately measure the pressure-volume-temperature (P-V-T) properties of fluids over a temperature range of 80 K to 520 K and at pressures up to 35 MPa is in the final stages of development at NIST. The density of a fluid is determined by measuring the difference in the buoyancy forces experienced by two sinkers of identical mass, surface area, and surface material, but very different volumes. The buoyancy forces on the sinkers are transmitted to a semi-microbalance by means of a magnetic suspension coupling. This paper reviews the principle of the measurement and describes the overall design of the system.

  18. Accuracy of velocities from repeated GPS measurements

    NASA Astrophysics Data System (ADS)

    Akarsu, V.; Sanli, D. U.; Arslan, E.

    2015-04-01

    Today repeated GPS measurements are still in use, because we cannot always employ GPS permanent stations due to a variety of limitations. One area of study that uses velocities/deformation rates from repeated GPS measurements is the monitoring of crustal motion. This paper discusses the quality of the velocities derived using repeated GPS measurements for the aim of monitoring crustal motion. From a global network of International GNSS Service (IGS) stations, we processed GPS measurements repeated monthly and annually spanning nearly 15 years and estimated GPS velocities for GPS baseline components latitude, longitude and ellipsoidal height. We used web-based GIPSY for the processing. Assuming true deformation rates can only be determined from the solutions of 24 h observation sessions, we evaluated the accuracy of the deformation rates from 8 and 12 h sessions. We used statistical hypothesis testing to assess the velocities derived from short observation sessions. In addition, as an alternative control method we checked the accuracy of GPS solutions from short observation sessions against those of 24 h sessions referring to statistical criteria that measure the accuracy of regression models. Results indicate that the velocities of the vertical component are completely affected when repeated GPS measurements are used. The results also reveal that only about 30% of the 8 h solutions and about 40% of 12 h solutions for the horizontal coordinates are acceptable for velocity estimation. The situation is much worse for the vertical component in which none of the solutions from campaign measurements are acceptable for obtaining reliable deformation rates.

  19. Maximizing the quantitative accuracy and reproducibility of Förster resonance energy transfer measurement for screening by high throughput widefield microscopy.

    PubMed

    Schaufele, Fred

    2014-03-15

    Förster resonance energy transfer (FRET) between fluorescent proteins (FPs) provides insights into the proximities and orientations of FPs as surrogates of the biochemical interactions and structures of the factors to which the FPs are genetically fused. As powerful as FRET methods are, technical issues have impeded their broad adoption in the biologic sciences. One hurdle to accurate and reproducible FRET microscopy measurement stems from variable fluorescence backgrounds both within a field and between different fields. Those variations introduce errors into the precise quantification of fluorescence levels on which the quantitative accuracy of FRET measurement is highly dependent. This measurement error is particularly problematic for screening campaigns since minimal well-to-well variation is necessary to faithfully identify wells with altered values. High content screening depends also upon maximizing the numbers of cells imaged, which is best achieved by low magnification high throughput microscopy. But, low magnification introduces flat-field correction issues that degrade the accuracy of background correction to cause poor reproducibility in FRET measurement. For live cell imaging, fluorescence of cell culture media in the fluorescence collection channels for the FPs commonly used for FRET analysis is a high source of background error. These signal-to-noise problems are compounded by the desire to express proteins at biologically meaningful levels that may only be marginally above the strong fluorescence background. Here, techniques are presented that correct for background fluctuations. Accurate calculation of FRET is realized even from images in which a non-flat background is 10-fold higher than the signal. PMID:23927839

  20. Maximizing the quantitative accuracy and reproducibility of Förster resonance energy transfer measurement for screening by high throughput widefield microscopy

    PubMed Central

    Schaufele, Fred

    2013-01-01

    Förster resonance energy transfer (FRET) between fluorescent proteins (FPs) provides insights into the proximities and orientations of FPs as surrogates of the biochemical interactions and structures of the factors to which the FPs are genetically fused. As powerful as FRET methods are, technical issues have impeded their broad adoption in the biologic sciences. One hurdle to accurate and reproducible FRET microscopy measurement stems from variable fluorescence backgrounds both within a field and between different fields. Those variations introduce errors into the precise quantification of fluorescence levels on which the quantitative accuracy of FRET measurement is highly dependent. This measurement error is particularly problematic for screening campaigns since minimal well-to-well variation is necessary to faithfully identify wells with altered values. High content screening depends also upon maximizing the numbers of cells imaged, which is best achieved by low magnification high throughput microscopy. But, low magnification introduces flat-field correction issues that degrade the accuracy of background correction to cause poor reproducibility in FRET measurement. For live cell imaging, fluorescence of cell culture media in the fluorescence collection channels for the FPs commonly used for FRET analysis is a high source of background error. These signal-to-noise problems are compounded by the desire to express proteins at biologically meaningful levels that may only be marginally above the strong fluorescence background. Here, techniques are presented that correct for background fluctuations. Accurate calculation of FRET is realized even from images in which a non-flat background is 10-fold higher than the signal. PMID:23927839

  1. Measuring the Accuracy of Diagnostic Systems

    NASA Astrophysics Data System (ADS)

    Swets, John A.

    1988-06-01

    Diagnostic systems of several kinds are used to distinguish between two classes of events, essentially ``signals'' and ``noise.'' For then, analysis in terms of the ``relative operating characteristic'' of signal detection theory provides a precise and valid measure of diagnostic accuracy. It is the only measure available that is uninfluenced by decision biases and prior probabilities, and it places the performances of diverse systems on a common, easily interpreted scale. Representative values of this measure are reported here for systems in medical imaging, materials testing, weather forecasting, information retrieval, polygraph lie detection, and aptitude testing. Though the measure itself is sound, the values obtained from tests of diagnostic systems often require qualification because the test data on which they are based are of unsure quality. A common set of problems in testing is faced in all fields. How well these problems are handled, or can be handled in a given field, determines the degree of confidence that can be placed in a measured value of accuracy. Some fields fare much better than others.

  2. Accuracy testing of electric groundwater-level measurement tapes

    USGS Publications Warehouse

    Jelinski, Jim; Clayton, Christopher S.; Fulford, Janice M.

    2015-01-01

    The accuracy tests demonstrated that none of the electric-tape models tested consistently met the suggested USGS accuracy of ±0.01 ft. The test data show that the tape models in the study should give a water-level measurement that is accurate to roughly ±0.05 ft per 100 ft without additional calibration. To meet USGS accuracy guidelines, the electric-tape models tested will need to be individually calibrated. Specific conductance also plays a part in tape accuracy. The probes will not work in water with specific conductance values near zero, and the accuracy of one probe was unreliable in very high conductivity water (10,000 microsiemens per centimeter).

  3. James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

    NASA Technical Reports Server (NTRS)

    Comber, Brian; Glazer, Stuart

    2012-01-01

    The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018. Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zoned results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space environment Simulator (SES). The flight external radiators are not available during ISIM-level thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided by specially designed test hardware which also measures the heat flow within each of the five heat straps to an accuracy of less than 2 mW, which is less than 5% of the minimum predicted heat flow values. Measurement of the heat loads to this accuracy is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. It also provides direct verification by test of several high-level thermal requirements. Devices that measure heat flow in this manner have historically been referred to a "Q-meters". Perhaps the most important feature of the design of the JWST Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on knowledge of precise heater power required to maintain a constant temperature difference between sensors on two stages, for which a table is empirically developed during a

  4. High-accuracy measurements of N2O concentration and isotopic composition of low and high concentration samples with small volume injections using Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Saad, Nabil; Palmer, Melissa; Huang, Kuan

    2015-04-01

    Nitrous oxide (N2O) gas is among the major contributors to global warming and ozone depletion in stratosphere. Quantitative estimate of N2O production in various pathways and N2O fluxes across different reservoirs is the key to understanding the role of N2O in the global change. To achieve this goal, accurate and concurrent measurement of both N2O concentration ([N2O]) and its associated isotopic ratios (δ 15Nα , δ 15{N}β & δ 18O) is desired. Recent developments in Cavity Ring-Down Spectroscopy (CRDS) have enabled high-precision measurements of [N2O] and Site-Preference-δ 15N (SP-δ 15N) and δ 18O of a continuous gas flow. However, many N2O samples are discrete with limited volume ( 2 ppm), and are not suitable for direct continuous measurements by CRDS. Here we present results of a small sample introduction and handling device, labelled as Small Sample Isotope Module (SSIM), coupled to and automatically coordinated with a Picarro isotopic N2O CRDS analyzer to handle and measure high concentration and/or small volume samples. The SSIM requires 20 ml of sample volume per analysis at STP, and transfers the sample to the CRDS for high-precision concentration and isotope ratio measurements. When the injected sample is

  5. Accuracy evaluation of residual stress measurements

    SciTech Connect

    Yerman, J.A.; Kroenke, W.C.; Long, W.H.

    1996-05-01

    The accuracy of residual stress measurement techniques is difficult to assess due to the lack of available reference standards. To satisfy the need for reference standards, two specimens were designed and developed to provide known stress magnitudes and distributions: one with a uniform stress distribution and one with a nonuniform linear stress distribution. A reusable, portable load fixture was developed for use with each of the two specimens. Extensive bench testing was performed to determine if the specimens provide desired known stress magnitudes and distributions and stability of the known stress with time. The testing indicated that the nonuniform linear specimen and load fixture provided the desired known stress magnitude and distribution but that modifications were required for the uniform stress specimen. A trial use of the specimens and load fixtures using hole drilling was successful.

  6. High-accuracy measurements of N2O concentration and site-specific nitrogen isotopes in small or high concentration samples

    NASA Astrophysics Data System (ADS)

    Palmer, M. R.; Arata, C.; Huang, K.

    2014-12-01

    Nitrous oxide (N2O) gas is among the major contributors to global warming and ozone depletion in stratosphere. Quantitative estimate of N­2O production in various pathways and N­2O fluxes across different reservoirs is the key to understanding the role of N­2O in the global change. To achieve this goal, accurate and concurrent measurement of both N2O concentration ([N2O]) and its site-specific isotopic composition (SP-δ15N), namely δ15Nα and δ15Nβ, is desired. Recent developments in Cavity Ring-Down Spectroscopy (CRDS) have enabled high precision measurements of [N2O] and SP-δ15N of a continuous gas flow. However, many N­­2O samples are discrete with limited volume (< 500 ml), and/or high [N2O] (> 2 ppm), and are not suitable for direct measurements by CRDS. Here we present results of a Small Sample Isotope Module 2 (SSIM2) which is coupled to and automatically coordinated with a Picarro isotopic N2O CRDS analyzer to handle and measure high concentration and/or small volume samples. The SSIM2 requires 20 ml of sample per analysis, and transfers the sample to the CRDS for high precision measurement. When the sample injection is < 20 ml, a zero gas is optionally filled to make up the volume. We used the SSIM2 to dilute high [N2O] samples and < 20 ml samples, and tested the effect of dilution on the measured SP-δ15N. In addition, we employed and tested a newly developed double injection method for samples adequate for two 20 ml injections. After the SSIM2 and the CRDS cavity was primed with the first injection, the second injection, which has negligible dilution of the sample, can be accurately measured for both [N2O] and SP-δ15N. Results of these experiments indicate that the precision of SSIM2-CRDS is similar to that of the continuous measurements using the CRDS alone, and that dilution has minimal effect on SP-δ15N, as along as the [N2O] is > 300 ppb after dilution. Overall, the precision of SP-δ15N measured using the SSIM2 is < 0.5 ‰.

  7. The accuracy of breast volume measurement methods: A systematic review.

    PubMed

    Choppin, S B; Wheat, J S; Gee, M; Goyal, A

    2016-08-01

    Breast volume is a key metric in breast surgery and there are a number of different methods which measure it. However, a lack of knowledge regarding a method's accuracy and comparability has made it difficult to establish a clinical standard. We have performed a systematic review of the literature to examine the various techniques for measurement of breast volume and to assess their accuracy and usefulness in clinical practice. Each of the fifteen studies we identified had more than ten live participants and assessed volume measurement accuracy using a gold-standard based on the volume, or mass, of a mastectomy specimen. Many of the studies from this review report large (>200 ml) uncertainty in breast volume and many fail to assess measurement accuracy using appropriate statistical tools. Of the methods assessed, MRI scanning consistently demonstrated the highest accuracy with three studies reporting errors lower than 10% for small (250 ml), medium (500 ml) and large (1000 ml) breasts. However, as a high-cost, non-routine assessment other methods may be more appropriate. PMID:27288864

  8. High Accuracy Transistor Compact Model Calibrations

    SciTech Connect

    Hembree, Charles E.; Mar, Alan; Robertson, Perry J.

    2015-09-01

    Typically, transistors are modeled by the application of calibrated nominal and range models. These models consists of differing parameter values that describe the location and the upper and lower limits of a distribution of some transistor characteristic such as current capacity. Correspond- ingly, when using this approach, high degrees of accuracy of the transistor models are not expected since the set of models is a surrogate for a statistical description of the devices. The use of these types of models describes expected performances considering the extremes of process or transistor deviations. In contrast, circuits that have very stringent accuracy requirements require modeling techniques with higher accuracy. Since these accurate models have low error in transistor descriptions, these models can be used to describe part to part variations as well as an accurate description of a single circuit instance. Thus, models that meet these stipulations also enable the calculation of quantifi- cation of margins with respect to a functional threshold and uncertainties in these margins. Given this need, new model high accuracy calibration techniques for bipolar junction transis- tors have been developed and are described in this report.

  9. Oligomer formation pathways in secondary organic aerosol from MS and MS/MS measurements with high mass accuracy and resolving power.

    PubMed

    Hall, Wiley A; Johnston, Murray V

    2012-06-01

    Secondary organic aerosol (SOA) is formed when organic molecules react with oxidants in the gas phase to form particulate matter. Recent measurements have shown that more than half of the mass of laboratory-generated SOA consists of high molecular weight oligomeric compounds. In this work, the formation mechanisms of oligomers produced in the laboratory by ozonolysis of α-pinene, an important SOA precursor in ambient air, are studied by MS and MS/MS measurements with high accuracy and resolving power to characterize monomer building blocks and the reactions that couple them together. The distribution of oligomers in an SOA sample is complex, typically yielding over 1000 elemental formulas that can be assigned from an electrospray ionization mass spectrum. Despite this complexity, MS/MS spectra can be found that give strong evidence for specific oligomer formation pathways that have been postulated but not confirmed. These include aldol and gem-diol reactions of carbonyls as well as peroxyhemiacetal formation from hydroperoxides. The strongest evidence for carbonyl reactions is in the formation of hydrated products. Less compelling evidence is found for dehydrated products and secondary ozonide formation. The number of times that a monomer building block is observed as a fragmentation product in the MS/MS spectra is shown to be independent of the monomer vapor pressure, suggesting that oligomer formation is not driven by equilibrium partitioning of a monomer between the gas and particle phases, but rather by reactive uptake where a monomer collides with the particle surface and rapidly forms an oligomer. PMID:22476934

  10. Oligomer Formation Pathways in Secondary Organic Aerosol from MS and MS/MS Measurements with High Mass Accuracy and Resolving Power

    NASA Astrophysics Data System (ADS)

    Hall, Wiley A.; Johnston, Murray V.

    2012-06-01

    Secondary organic aerosol (SOA) is formed when organic molecules react with oxidants in the gas phase to form particulate matter. Recent measurements have shown that more than half of the mass of laboratory-generated SOA consists of high molecular weight oligomeric compounds. In this work, the formation mechanisms of oligomers produced in the laboratory by ozonolysis of α-pinene, an important SOA precursor in ambient air, are studied by MS and MS/MS measurements with high accuracy and resolving power to characterize monomer building blocks and the reactions that couple them together. The distribution of oligomers in an SOA sample is complex, typically yielding over 1000 elemental formulas that can be assigned from an electrospray ionization mass spectrum. Despite this complexity, MS/MS spectra can be found that give strong evidence for specific oligomer formation pathways that have been postulated but not confirmed. These include aldol and gem-diol reactions of carbonyls as well as peroxyhemiacetal formation from hydroperoxides. The strongest evidence for carbonyl reactions is in the formation of hydrated products. Less compelling evidence is found for dehydrated products and secondary ozonide formation. The number of times that a monomer building block is observed as a fragmentation product in the MS/MS spectra is shown to be independent of the monomer vapor pressure, suggesting that oligomer formation is not driven by equilibrium partitioning of a monomer between the gas and particle phases, but rather by reactive uptake where a monomer collides with the particle surface and rapidly forms an oligomer.

  11. High accuracy in short ISS missions

    NASA Astrophysics Data System (ADS)

    Rüeger, J. M.

    1986-06-01

    Traditionally Inertial Surveying Systems ( ISS) are used for missions of 30 km to 100 km length. Today, a new type of ISS application is emanating from an increased need for survey control densification in urban areas often in connection with land information systems or cadastral surveys. The accuracy requirements of urban surveys are usually high. The loss in accuracy caused by the coordinate transfer between IMU and ground marks is investigated and an offsetting system based on electronic tacheometers is proposed. An offsetting system based on a Hewlett-Packard HP 3820A electronic tacheometer has been tested in Sydney (Australia) in connection with a vehicle mounted LITTON Auto-Surveyor System II. On missions over 750 m ( 8 stations, 25 minutes duration, 3.5 minute ZUPT intervals, mean offset distances 9 metres) accuracies of 37 mm (one sigma) in position and 8 mm in elevation were achieved. Some improvements to the LITTON Auto-Surveyor System II are suggested which would improve the accuracies even further.

  12. High Accuracy Fuel Flowmeter, Phase 1

    NASA Technical Reports Server (NTRS)

    Mayer, C.; Rose, L.; Chan, A.; Chin, B.; Gregory, W.

    1983-01-01

    Technology related to aircraft fuel mass - flowmeters was reviewed to determine what flowmeter types could provide 0.25%-of-point accuracy over a 50 to one range in flowrates. Three types were selected and were further analyzed to determine what problem areas prevented them from meeting the high accuracy requirement, and what the further development needs were for each. A dual-turbine volumetric flowmeter with densi-viscometer and microprocessor compensation was selected for its relative simplicity and fast response time. An angular momentum type with a motor-driven, spring-restrained turbine and viscosity shroud was selected for its direct mass-flow output. This concept also employed a turbine for fast response and a microcomputer for accurate viscosity compensation. The third concept employed a vortex precession volumetric flowmeter and was selected for its unobtrusive design. Like the turbine flowmeter, it uses a densi-viscometer and microprocessor for density correction and accurate viscosity compensation.

  13. Measuring the positional accuracy of computer assisted surgical tracking systems.

    PubMed

    Clarke, J V; Deakin, A H; Nicol, A C; Picard, F

    2010-01-01

    Computer Assisted Orthopaedic Surgery (CAOS) technology is constantly evolving with support from a growing number of clinical trials. In contrast, reports of technical accuracy are scarce, with there being no recognized guidelines for independent measurement of the basic static performance of computer assisted systems. To address this problem, a group of surgeons, academics and manufacturers involved in the field of CAOS collaborated with the American Society for Testing and Materials (ASTM) International and drafted a set of standards for measuring and reporting the technical performance of such systems. The aims of this study were to use these proposed guidelines in assessing the positional accuracy of both a commercially available and a novel tracking system. A standardized measurement object model based on the ASTM guidelines was designed and manufactured to provide an array of points in space. Both the Polaris camera with associated active infrared trackers and a novel system that used a small visible-light camera (MicronTracker) were evaluated by measuring distances and single point repeatability. For single point registration the measurements were obtained both manually and with the pointer rigidly clamped to eliminate human movement artifact. The novel system produced unacceptably large distance errors and was not evaluated beyond this stage. The commercial system was precise and its accuracy was well within the expected range. However, when the pointer was held manually, particularly by a novice user, the results were significantly less precise by a factor of almost ten. The ASTM guidelines offer a simple, standardized method for measuring positional accuracy and could be used to enable independent testing of tracking systems. The novel system demonstrated a high level of inaccuracy that made it inappropriate for clinical testing. The commercially available tracking system performed well within expected limits under optimal conditions, but revealed a

  14. 40 CFR 86.1338-84 - Emission measurement accuracy.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Emission measurement accuracy. 86.1338... Procedures § 86.1338-84 Emission measurement accuracy. (a) Measurement accuracy—Bag sampling. (1) Good... using the calibration data obtained with both calibration gases. (b) Measurement...

  15. 40 CFR 86.1338-84 - Emission measurement accuracy.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Emission measurement accuracy. 86.1338... Procedures § 86.1338-84 Emission measurement accuracy. (a) Measurement accuracy—Bag sampling. (1) Good... using the calibration data obtained with both calibration gases. (b) Measurement...

  16. 40 CFR 86.1338-84 - Emission measurement accuracy.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Emission measurement accuracy. 86.1338... Procedures § 86.1338-84 Emission measurement accuracy. (a) Measurement accuracy—Bag sampling. (1) Good... using the calibration data obtained with both calibration gases. (b) Measurement...

  17. Note: Optical and electronic design of an amplitude-modulated continuous-wave laser scanner for high-accuracy distance measurement

    SciTech Connect

    Jang, Junhwan; Hwang, Sungui; Park, Kyihwan

    2015-04-15

    To utilize a time-of-flight-based laser scanner as a distance measurement sensor, the measurable distance and accuracy are the most important performance parameters to consider. For these purposes, the optical system and electronic signal processing of the laser scanner should be optimally designed in order to reduce a distance error caused by the optical crosstalk and wide dynamic range input. Optical system design for removing optical crosstalk problem is proposed in this work. Intensity control is also considered to solve the problem of a phase-shift variation in the signal processing circuit caused by object reflectivity. The experimental results for optical system and signal processing design are performed using 3D measurements.

  18. High accuracy wall thickness loss monitoring

    NASA Astrophysics Data System (ADS)

    Gajdacsi, Attila; Cegla, Frederic

    2014-02-01

    Ultrasonic inspection of wall thickness in pipes is a standard technique applied widely in the petrochemical industry. The potential precision of repeat measurements with permanently installed ultrasonic sensors however significantly surpasses that of handheld sensors as uncertainties associated with coupling fluids and positional offsets are eliminated. With permanently installed sensors the precise evaluation of very small wall loss rates becomes feasible in a matter of hours. The improved accuracy and speed of wall loss rate measurements can be used to evaluate and develop more effective mitigation strategies. This paper presents an overview of factors causing variability in the ultrasonic measurements which are then systematically addressed and an experimental setup with the best achievable stability based on these considerations is presented. In the experimental setup galvanic corrosion is used to induce predictable and very small wall thickness loss. Furthermore, it is shown that the experimental measurements can be used to assess the effect of reduced wall loss that is produced by the injection of corrosion inhibitor. The measurements show an estimated standard deviation of about 20nm, which in turn allows us to evaluate the effect and behaviour of corrosion inhibitors within less than an hour.

  19. The use of low density high accuracy (LDHA) data for correction of high density low accuracy (HDLA) point cloud

    NASA Astrophysics Data System (ADS)

    Rak, Michal Bartosz; Wozniak, Adam; Mayer, J. R. R.

    2016-06-01

    Coordinate measuring techniques rely on computer processing of coordinate values of points gathered from physical surfaces using contact or non-contact methods. Contact measurements are characterized by low density and high accuracy. On the other hand optical methods gather high density data of the whole object in a short time but with accuracy at least one order of magnitude lower than for contact measurements. Thus the drawback of contact methods is low density of data, while for non-contact methods it is low accuracy. In this paper a method for fusion of data from two measurements of fundamentally different nature: high density low accuracy (HDLA) and low density high accuracy (LDHA) is presented to overcome the limitations of both measuring methods. In the proposed method the concept of virtual markers is used to find a representation of pairs of corresponding characteristic points in both sets of data. In each pair the coordinates of the point from contact measurements is treated as a reference for the corresponding point from non-contact measurement. Transformation enabling displacement of characteristic points from optical measurement to their match from contact measurements is determined and applied to the whole point cloud. The efficiency of the proposed algorithm was evaluated by comparison with data from a coordinate measuring machine (CMM). Three surfaces were used for this evaluation: plane, turbine blade and engine cover. For the planar surface the achieved improvement was of around 200 μm. Similar results were obtained for the turbine blade but for the engine cover the improvement was smaller. For both freeform surfaces the improvement was higher for raw data than for data after creation of mesh of triangles.

  20. 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.

  1. High accuracy wavelength calibration for a scanning visible spectrometer.

    PubMed

    Scotti, Filippo; Bell, Ronald E

    2010-10-01

    Spectroscopic applications for plasma velocity measurements often require wavelength accuracies ≤0.2 Å. 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 ∼0.25 Å has been demonstrated. With the addition of a high resolution (0.075 arc  sec) optical encoder on the grating stage, greater precision (∼0.005 Å) is possible, allowing absolute velocity measurements within ∼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. PMID:21033925

  2. 40 CFR 86.338-79 - Exhaust measurement accuracy.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Exhaust measurement accuracy. 86.338....338-79 Exhaust measurement accuracy. (a) The analyzers must be operated between 15 percent and 100 percent of full-scale chart deflection during the measurement of the emissions for each mode....

  3. 40 CFR 86.338-79 - Exhaust measurement accuracy.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Exhaust measurement accuracy. 86.338....338-79 Exhaust measurement accuracy. (a) The analyzers must be operated between 15 percent and 100 percent of full-scale chart deflection during the measurement of the emissions for each mode....

  4. Guiding Center Equations of High Accuracy

    SciTech Connect

    R.B. White, G. Spizzo and M. Gobbin

    2013-03-29

    Guiding center simulations are an important means of predicting the effect of resistive and ideal magnetohydrodynamic instabilities on particle distributions in toroidal magnetically confined thermonuclear fusion research devices. Because saturated instabilities typically have amplitudes of δ B/B of a few times 10-4 numerical accuracy is of concern in discovering the effect of mode particle resonances. We develop a means of following guiding center orbits which is greatly superior to the methods currently in use. In the presence of ripple or time dependent magnetic perturbations both energy and canonical momentum are conserved to better than one part in 1014, and the relation between changes in canonical momentum and energy is also conserved to very high order.

  5. Accuracy of Lidar Measurements of the Atmosphere

    NASA Technical Reports Server (NTRS)

    Kavaya, M. J.; Menzies, R. T.

    1986-01-01

    Report reviews sources of systematic error in laser radar (lidar) measurements of particles in atmosphere. Report applies particularly to stationary pulsed carbon dioxide lidars of type used to measure backscatter from aerosols in troposphere. Provides information for calibrating such systems accurately and consistently and interpreting their data correctly. Also useful in calibrating mobile and airborne lidars, lidars operating at wavelengths other than those of carbon dioxide lasers, and continuouswave lidars.

  6. 40 CFR 86.338-79 - Exhaust measurement accuracy.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Exhaust measurement accuracy. 86.338... Regulations for New Gasoline-Fueled and Diesel-Fueled Heavy-Duty Engines; Gaseous Exhaust Test Procedures § 86.338-79 Exhaust measurement accuracy. (a) The analyzers must be operated between 15 percent and...

  7. 30 CFR 74.8 - Measurement, accuracy, and reliability requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Measurement, accuracy, and reliability... Monitors § 74.8 Measurement, accuracy, and reliability requirements. (a) Breathing zone...

  8. 30 CFR 74.8 - Measurement, accuracy, and reliability requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Measurement, accuracy, and reliability... Monitors § 74.8 Measurement, accuracy, and reliability requirements. (a) Breathing zone...

  9. Students' Accuracy of Measurement Estimation: Context, Units, and Logical Thinking

    ERIC Educational Resources Information Center

    Jones, M. Gail; Gardner, Grant E.; Taylor, Amy R.; Forrester, Jennifer H.; Andre, Thomas

    2012-01-01

    This study examined students' accuracy of measurement estimation for linear distances, different units of measure, task context, and the relationship between accuracy estimation and logical thinking. Middle school students completed a series of tasks that included estimating the length of various objects in different contexts and completed a test…

  10. Developing a Weighted Measure of Speech Sound Accuracy

    PubMed Central

    Preston, Jonathan L.; Ramsdell, Heather L.; Oller, D. Kimbrough; Edwards, Mary Louise; Tobin, Stephen J.

    2010-01-01

    Purpose The purpose is to develop a system for numerically quantifying a speaker’s phonetic accuracy through transcription-based measures. With a focus on normal and disordered speech in children, we describe a system for differentially weighting speech sound errors based on various levels of phonetic accuracy with a Weighted Speech Sound Accuracy (WSSA) score. We then evaluate the reliability and validity of this measure. Method Phonetic transcriptions are analyzed from several samples of child speech, including preschoolers and young adolescents with and without speech sound disorders and typically developing toddlers. The new measure of phonetic accuracy is compared to existing measures, is used to discriminate typical and disordered speech production, and is evaluated to determine whether it is sensitive to changes in phonetic accuracy over time. Results Initial psychometric data indicate that WSSA scores correlate with other measures of phonetic accuracy as well as listeners’ judgments of severity of a child’s speech disorder. The measure separates children with and without speech sound disorders. WSSA scores also capture growth in phonetic accuracy in toddler’s speech over time. Conclusion Results provide preliminary support for the WSSA as a valid and reliable measure of phonetic accuracy in children’s speech. PMID:20699344

  11. Improving Localization Accuracy: Successive Measurements Error Modeling

    PubMed Central

    Abu Ali, Najah; Abu-Elkheir, Mervat

    2015-01-01

    Vehicle self-localization is an essential requirement for many of the safety applications envisioned for vehicular networks. The mathematical models used in current vehicular localization schemes focus on modeling the localization error itself, and overlook the potential correlation between successive localization measurement errors. In this paper, we first investigate the existence of correlation between successive positioning measurements, and then incorporate this correlation into the modeling positioning error. We use the Yule Walker equations to determine the degree of correlation between a vehicle’s future position and its past positions, and then propose a p-order Gauss–Markov model to predict the future position of a vehicle from its past p positions. We investigate the existence of correlation for two datasets representing the mobility traces of two vehicles over a period of time. We prove the existence of correlation between successive measurements in the two datasets, and show that the time correlation between measurements can have a value up to four minutes. Through simulations, we validate the robustness of our model and show that it is possible to use the first-order Gauss–Markov model, which has the least complexity, and still maintain an accurate estimation of a vehicle’s future location over time using only its current position. Our model can assist in providing better modeling of positioning errors and can be used as a prediction tool to improve the performance of classical localization algorithms such as the Kalman filter. PMID:26140345

  12. Intelligence: The Speed and Accuracy Tradeoff in High Aptitude Individuals.

    ERIC Educational Resources Information Center

    Lajoie, Suzanne P.; Shore, Bruce M.

    1986-01-01

    The relative contributions of mental speed and accuracy to Primary Mental Ability (PMA) IQ prediction were studied in 52 high ability grade 10 students. Both speed and accuracy independently predicted IQ, but not speed over and above accuracy. Accuracy was demonstrated to be universally advantageous in IQ performance, but speed varied according to…

  13. Impact of Digital Panoramic Radiograph Magnification on Vertical Measurement Accuracy

    PubMed Central

    El Hage, Marc; Bernard, Jean-Pierre; Combescure, Christophe; Vazquez, Lydia

    2015-01-01

    Objectives. The purpose of this panoramic radiography study was to assess the impact of image magnification on the accuracy of vertical measurements in the posterior mandible. Methods. Six dental implants, inserted in the posterior segments of a resin model, were used as reference objects. Two observers performed implant length measurements using a proprietary viewer with two preset image magnifications: the low (1.9 : 1) and the medium (3.4 : 1) image magnifications. They also measured the implant lengths in two Digital Imaging Communications in Medicine viewers set at low (1.9 : 1), medium (3.4 : 1), and high (10 : 1) image magnifications. Results. The error between the measured length and the real implant length was close to zero for all three viewers and image magnifications. The percentage of measurements equal to the real implant length was the highest (83.3%) for the high image magnification and below 30% for all viewers with the low image magnification. Conclusions. The high and medium image magnifications used in this study allowed accurate vertical measurements, with all three imaging programs, in the posterior segments of a mandibular model. This study suggests that a low image magnification should not be used for vertical measurements on digital panoramic radiographs when planning an implant in the posterior mandible. PMID:26557851

  14. IRCM spectral signature measurements instrumentation featuring enhanced radiometric accuracy

    NASA Astrophysics Data System (ADS)

    Lantagne, Stéphane; Prel, Florent; Moreau, Louis; Roy, Claude; Willers, Cornelius J.

    2015-10-01

    Hyperspectral Infrared (IR) signature measurements are performed in military applications including aircraft- and -naval vessel stealth characterization, detection/lock-on ranges, and flares efficiency characterization. Numerous military applications require high precision measurement of infrared signature characterization. For instance, Infrared Countermeasure (IRCM) systems and Infrared Counter-Countermeasure (IRCCM) system are continuously evolving. Infrared flares defeated IR guided seekers, IR flares became defeated by intelligent IR guided seekers and Jammers defeated the intelligent IR guided seekers [7]. A precise knowledge of the target infrared signature phenomenology is crucial for the development and improvement of countermeasure and counter-countermeasure systems and so precise quantification of the infrared energy emitted from the targets requires accurate spectral signature measurements. Errors in infrared characterization measurements can lead to weakness in the safety of the countermeasure system and errors in the determination of detection/lock-on range of an aircraft. The infrared signatures are analyzed, modeled, and simulated to provide a good understanding of the signature phenomenology to improve the IRCM and IRCCM technologies efficiency [7,8,9]. There is a growing need for infrared spectral signature measurement technology in order to further improve and validate infrared-based models and simulations. The addition of imagery to Spectroradiometers is improving the measurement capability of complex targets and scenes because all elements in the scene can now be measured simultaneously. However, the limited dynamic range of the Focal Plane Array (FPA) sensors used in these instruments confines the ranges of measurable radiance intensities. This ultimately affects the radiometric accuracy of these complex signatures. We will describe and demonstrate how the ABB hyperspectral imaging spectroradiometer features enhanced the radiometric accuracy

  15. 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}.

  16. Developing a Weighted Measure of Speech Sound Accuracy

    ERIC Educational Resources Information Center

    Preston, Jonathan L.; Ramsdell, Heather L.; Oller, D. Kimbrough; Edwards, Mary Louise; Tobin, Stephen J.

    2011-01-01

    Purpose: To develop a system for numerically quantifying a speaker's phonetic accuracy through transcription-based measures. With a focus on normal and disordered speech in children, the authors describe a system for differentially weighting speech sound errors on the basis of various levels of phonetic accuracy using a Weighted Speech Sound…

  17. Accuracy of orthodontic force and tooth movement measurements.

    PubMed

    Lundgren, D; Owman-Moll, P; Kurol, J; Mårtensson, B

    1996-08-01

    This study was designed to test the accuracy of measurement methods for assessment of force and tooth movement in orthodontic procedures. Daily in vivo measurements of the force produced by activated archwires showed that the initial force declined substantially (by 20 per cent of mean value) within 3 days. Both the 'trueness' (validity) and precision of the force measurements, obtained with a strain gauge, were found to be high (SD values were 1.0 cN and 0.4 cN, respectively). Horizontal tooth movements were measured with three different instruments: a slide calliper, a co-ordinate measuring machine, and laser measuring equipment based on holograms. There was a good level of agreement between these methods. This was also confirmed by calibration data. The precision of the methods was (SD values) 0.06, 0.07, and 0.13 mm, respectively. The benefits of the use of the co-ordinate measuring machine are obvious, since it can measure tooth movements in relation to reference planes in all directions. PMID:8894157

  18. High accuracy refractive index measurement system for germanium and silicon using the channelled spectrum method in the range of 3 to 15 μm

    NASA Astrophysics Data System (ADS)

    Straube, Hilmar; Hell, Christian

    2016-05-01

    The refractive index of germanium is known only up to the third decimal according to publicly available sources. This data from various authors shows deviations in the order of several 10-3 not to be explained by experimental errors of the refractive index measurement. This is a strong indication that there is optically relevant material property variation. We present an interferometric method to measure the refractive index and its temperature dependency on etalon samples, which are cheaper to prepare with high quality than prism samples needed for the classical method of index measurement. Resolution and stability of our method is better than 10-4. The method can be used for both germanium and silicon. Our goal is to be able to produce material with optically relevant specifications. This is in contrast to the conventional method of specifying these important IR-optical materials in terms of electrical properties such as dopant type and concentration.

  19. High accuracy ground target location using loitering munitions platforms

    NASA Astrophysics Data System (ADS)

    Wang, Zhifei; Wang, Hua; Han, Jing

    2011-08-01

    Precise ground target localization is an interesting problem and relevant not only for military but also for civilian applications, and this is expected to be an emerging field with many potential applications. Ground Target Location Using Loitering Munitions (LM) requires estimation of aircraft position and attitude to a high degree of accuracy, and data derived by processing sensor images might be useful for supplementing other navigation sensor information and increasing the reliability and accuracy of navigation estimates during this flight phase. This paper presents a method for high accuracy ground target localization using Loitering Munitions (LM) equipped with a video camera sensor. The proposed method is based on a satellite or aerial image matching technique. In order to acquire the target position of ground intelligently and rapidly and to improve the localization accuracy estimating the target position jointly with the systematic LM and camera attitude measurement errors, several techniques have been proposed. Firstly, ground target geo-location based on tray tracing was used for comparison against our approach. By proposed methods the calculation from pixel to world coordinates can be done. Then Hough transform was used to image alignment and a median filter was applied for removing small details which are visible from the sensed image but not visible from the reference image. Finally, A novel edge detection method and an image matching algorithm based on bifurcation extraction were proposed. This method did not require accurate knowledge of the aircraft position and attitude and high performance sensors, therefore it is especially suitable for LM which did not have capability to carry accurate sensors due to their limited play weight and power resources. The results of simulation experiments and theory analyzing demonstrate that high accuracy ground target localization is reached with low performance sensors, and achieve timely. The method is used in

  20. High-accuracy particle sizing by interferometric particle imaging

    NASA Astrophysics Data System (ADS)

    Qieni, Lü; Wenhua, Jin; Tong, Lü; Xiang, Wang; Yimo, Zhang

    2014-02-01

    A method of high-accuracy estimation of fringes number/fringes frequency of interferogram based on erosion match and the Fourier transform technique is proposed. The edge images of the interference pattern of particles and the particle mask image are detected respectively by erosion operating firstly and then subtracted with the respective original image, and the center coordinate of particles can be extracted through the 2D correlation operation for the two edge images obtained. The interference pattern of each particle can then be achieved using the center coordinate, the shape and size of the particle image. The number of fringes/fringe spacing of the interferogram of the particle is extracted by Fourier transform and the modified Rife algorithm, and sub-pixel accuracy of the extracted frequency is acquired. Its performance is demonstrated by numerical simulation and experimental measurement. The measurement uncertainty is ±0.91 μm and the relative error 1.13% for the standard particle of diameter 45 μm. The research results show that the algorithm presented boasts high accuracy for particle sizing as well as location measurement.

  1. Development of an in situ calibration method for current-to-voltage converters for high-accuracy SI-traceable low dc current measurements

    NASA Astrophysics Data System (ADS)

    Eppeldauer, George P.; Yoon, Howard W.; Jarrett, Dean G.; Larason, Thomas C.

    2013-10-01

    For photocurrent measurements with low uncertainties, wide dynamic range reference current-to-voltage converters and a new converter calibration method have been developed at the National Institute of Standards and Technology (NIST). The high-feedback resistors of a reference converter were in situ calibrated on a high-resistivity, printed circuit board placed in an electrically shielded box electrically isolated from the operational amplifier using jumpers. The feedback resistors, prior to their installation, were characterized, selected and heat treated. The circuit board was cleaned with solvents, and the in situ resistors were calibrated using measurement systems for 10 kΩ to 10 GΩ standard resistors. We demonstrate that dc currents from 1 nA to 100 µA can be measured with uncertainties of 55 × 10-6 (k = 2) or lower, which are lower in uncertainties than any commercial device by factors of 10 to 30 at the same current setting. The internal (NIST) validations of the reference converter are described.

  2. The NASA High Accuracy Fuel Flowmeter (HAFF) Development Program

    NASA Technical Reports Server (NTRS)

    Hobart, H. F.

    1983-01-01

    The high accuracy fuel flowmeter development program is described. A flightworthy meter that measures mass flowrate of aircraft fuels to within + or - 0.25% of reading over a 50:1 range of flow is developed. A study of measurement techniques to achieve this goal yielded three candidates: (1) a dual turbine flowmeter with density and viscosity compensation; (2) an angular momentum flowmeter with a motor-driven, spring-restrained turbine and viscosity shroud; and (3) a vortex precission flowmeter with density and viscosity compensation. An experimental study of each technique was completed and the first two candidates were selected for prototype development.

  3. Proposal of AAA-battery-size one-shot ATR Fourier spectroscopic imager for on-site analysis: Simultaneous measurement of multi-components with high accuracy

    NASA Astrophysics Data System (ADS)

    Hosono, Satsuki; Qi, Wei; Sato, Shun; Suzuki, Yo; Fujiwara, Masaru; Hiramatsu, Hiroyuki; Suzuki, Satoru; Abeygunawardhana, P. K. W.; Wada, Kenji; Nishiyama, Akira; Ishimaru, Ichiro

    2015-03-01

    For simultaneous measurement of multi-components on-site like factories, the ultra-compact (diameter: 9[mm], length: 45[mm], weight: 200[g]) one-shot ATR (Attenuated Total Reflection) Fourier spectroscopic imager was proposed. Because the proposed one-shot Fourier spectroscopic imaging is based on spatial-phase-shift interferometer, interferograms could be obtained with simple optical configurations. We introduced the transmission-type relativeinclined phase-shifter, that was constructed with a cuboid prism and a wedge prism, onto the optical Fourier transform plane of infinity corrected optical systems. And also, small light-sources and cameras in the mid-infrared light region, whose size are several millimeter on a side, are essential components for the ultra-compact spectroscopic configuration. We selected the Graphite light source (light source area: 1.7×1.7[mm], maker: Hawkeye technologies) whose radiation factor was high. Fortunately, in these days we could apply the cost-effective 2-dimensional light receiving device for smartphone (e.g. product name: LEPTON, maker: FLIR, price: around 400USD). In the case of alcoholic drinks factory, conventionally workers measure glucose and ethanol concentrations by bringing liquid solution back to laboratories every day. The high portable spectroscopy will make it possible to measure multi-components simultaneously on manufacturing scene. But we found experimentally that absorption spectrum of glucose and water and ethanol were overlapped each other in near infrared light region. But for mid-infrared light region, we could distinguish specific absorption peaks of glucose (@10.5[μm]) and ethanol (@11.5[μm]) independently from water absorption. We obtained standard curve between absorption (@9.6[μm]) and ethanol concentration with high correlation coefficient 0.98 successfully by ATR imaging-type 2-dimensional Fourier spectroscopy (wavelength resolution: 0.057[μm]) with the graphite light source (maker: Hawkeye

  4. Accuracy of High-Resolution In Vivo Micro Magnetic Resonance Imaging for Measurements of Microstructural and Mechanical Properties of Human Distal Tibial Bone

    PubMed Central

    Liu, X. Sherry; Zhang, X. Henry; Rajapakse, Chamith S.; Wald, Michael J.; Magland, Jeremy; Sekhon, Kiranjit K.; Adam, Mark F.; Sajda, Paul; Wehrli, Felix W.; Guo, X. Edward

    2011-01-01

    Micro magnetic resonance imaging (µMRI) is an in vivo imaging method which permits three dimensional (3D) quantification of cortical and trabecular bone microstructure. µMR images can also be used for building microstructural finite element (µFE) models to assess bone stiffness, which highly correlates with bone’s resistance to fractures. In order for µMR image-based microstructural and µFE analyses to become standard clinical tools for assessing bone quality, validation with a current gold standard, namely the high-resolution micro computed tomography (µCT) is required. Microstructural measurements of 25 human cadaveric distal tibiae were performed for the registered µMR and µCT images, respectively. Next, whole bone stiffness, trabecular bone stiffness, and elastic moduli of cubic sub-volumes of trabecular bone in both µMR and µCT images were determined by voxel-based µFE analysis. The bone volume fraction (BV/TV), trabecular number (Tb.N*), trabecular spacing (Tb.Sp*), cortical thickness (Ct.Th), and structure model index (SMI) of µMRI showed strong correlations with µCT measurements (r2=0.67~0.97), and bone surface to volume ratio (BS/BV), connectivity density (Conn.D), and degree of anisotropy (DA) had significant but moderate correlations (r2=0.33~0.51). Each of these measurements also contributed to one or many of the µFE-predicted mechanical properties. However, model-independent trabecular thickness (Tb.Th*) of µMRI had no correlation with the µCT measurement and did not contribute to any mechanical measurement. Furthermore, the whole bone and trabecular bone stiffness of µMR images were highly correlated to those of µCT images (r2=0.86 and 0.96), suggesting that µMRI-based µFE analyses can directly and accurately quantify whole bone mechanical competence. In contrast, the elastic moduli of the µMRI trabecular bone sub-volume had significant but only moderate correlations with their gold standards (r2=0.40~0.58). We conclude that

  5. Accuracy Enhancement of Inertial Sensors Utilizing High Resolution Spectral Analysis

    PubMed Central

    Noureldin, Aboelmagd; Armstrong, Justin; El-Shafie, Ahmed; Karamat, Tashfeen; McGaughey, Don; Korenberg, Michael; Hussain, Aini

    2012-01-01

    In both military and civilian applications, the inertial navigation system (INS) and the global positioning system (GPS) are two complementary technologies that can be integrated to provide reliable positioning and navigation information for land vehicles. The accuracy enhancement of INS sensors and the integration of INS with GPS are the subjects of widespread research. Wavelet de-noising of INS sensors has had limited success in removing the long-term (low-frequency) inertial sensor errors. The primary objective of this research is to develop a novel inertial sensor accuracy enhancement technique that can remove both short-term and long-term error components from inertial sensor measurements prior to INS mechanization and INS/GPS integration. A high resolution spectral analysis technique called the fast orthogonal search (FOS) algorithm is used to accurately model the low frequency range of the spectrum, which includes the vehicle motion dynamics and inertial sensor errors. FOS models the spectral components with the most energy first and uses an adaptive threshold to stop adding frequency terms when fitting a term does not reduce the mean squared error more than fitting white noise. The proposed method was developed, tested and validated through road test experiments involving both low-end tactical grade and low cost MEMS-based inertial systems. The results demonstrate that in most cases the position accuracy during GPS outages using FOS de-noised data is superior to the position accuracy using wavelet de-noising.

  6. Free-Standing Zone Plate Optimized for He II 30.4 nm Solar Irradiance Measurements Having High Accuracy and Stability in Space

    NASA Astrophysics Data System (ADS)

    Seely, J. F.; McMullin, D. R.; Vest, R.; Sakdinawat, A.; Chang, C.; Jones, A. R.; Bremer, J.

    2015-12-01

    A zone plate was designed to record the He II 30.4 nm solar irradiance, was fabricated using electron beam lithography, and was absolutely calibrated using the NIST SURF synchrotron. The zone plate has an open support grid identical to those used to successfully launch transmission gratings in previous solar radiometers and is otherwise free-standing with no support membrane that would absorb EUV radiation. The measured efficiency of 3.0 ± 0.1% at 30.4 nm is consistent with detailed modeling of the efficiency and accounting for the geometrical transmittance of the support grid. The binary nature of the zone plate, consisting of opaque gold bars and open spaces with no support membrane, results in excellent long-term stability in space against contamination, radiation damage, and other effects that could alter the efficiency and instrument throughput. The zone plate's focusing property enables the rejection of out-of-band radiation by small apertures and high signal to background values that are superior to previous radiometers. The 4 mm outer diameter of the zone plate and the 25 mm focal length for 30.4 nm radiation enable a compact instrument that is attractive for small CubeSats and other space flight missions where resources are extremely limited.

  7. An accuracy measurement method for star trackers based on direct astronomic observation

    PubMed Central

    Sun, Ting; Xing, Fei; Wang, Xiaochu; You, Zheng; Chu, Daping

    2016-01-01

    Star tracker is one of the most promising optical attitude measurement devices and it is widely used in spacecraft for its high accuracy. However, how to realize and verify such an accuracy remains a crucial but unsolved issue until now. The authenticity of the accuracy measurement method of a star tracker will eventually determine the satellite performance. A new and robust accuracy measurement method for a star tracker based on the direct astronomical observation is proposed here. In comparison with the conventional method with simulated stars, this method utilizes real navigation stars as observation targets which makes the measurement results more authoritative and authentic. Transformations between different coordinate systems are conducted on the account of the precision movements of the Earth, and the error curves of directional vectors are obtained along the three axes. Based on error analysis and accuracy definitions, a three-axis accuracy evaluation criterion has been proposed in this paper, which could determine pointing and rolling accuracy of a star tracker directly. Experimental measurements confirm that this method is effective and convenient to implement. Such a measurement environment is close to the in-orbit conditions and it can satisfy the stringent requirement for high-accuracy star trackers. PMID:26948412

  8. An accuracy measurement method for star trackers based on direct astronomic observation

    NASA Astrophysics Data System (ADS)

    Sun, Ting; Xing, Fei; Wang, Xiaochu; You, Zheng; Chu, Daping

    2016-03-01

    Star tracker is one of the most promising optical attitude measurement devices and it is widely used in spacecraft for its high accuracy. However, how to realize and verify such an accuracy remains a crucial but unsolved issue until now. The authenticity of the accuracy measurement method of a star tracker will eventually determine the satellite performance. A new and robust accuracy measurement method for a star tracker based on the direct astronomical observation is proposed here. In comparison with the conventional method with simulated stars, this method utilizes real navigation stars as observation targets which makes the measurement results more authoritative and authentic. Transformations between different coordinate systems are conducted on the account of the precision movements of the Earth, and the error curves of directional vectors are obtained along the three axes. Based on error analysis and accuracy definitions, a three-axis accuracy evaluation criterion has been proposed in this paper, which could determine pointing and rolling accuracy of a star tracker directly. Experimental measurements confirm that this method is effective and convenient to implement. Such a measurement environment is close to the in-orbit conditions and it can satisfy the stringent requirement for high-accuracy star trackers.

  9. An accuracy measurement method for star trackers based on direct astronomic observation.

    PubMed

    Sun, Ting; Xing, Fei; Wang, Xiaochu; You, Zheng; Chu, Daping

    2016-01-01

    Star tracker is one of the most promising optical attitude measurement devices and it is widely used in spacecraft for its high accuracy. However, how to realize and verify such an accuracy remains a crucial but unsolved issue until now. The authenticity of the accuracy measurement method of a star tracker will eventually determine the satellite performance. A new and robust accuracy measurement method for a star tracker based on the direct astronomical observation is proposed here. In comparison with the conventional method with simulated stars, this method utilizes real navigation stars as observation targets which makes the measurement results more authoritative and authentic. Transformations between different coordinate systems are conducted on the account of the precision movements of the Earth, and the error curves of directional vectors are obtained along the three axes. Based on error analysis and accuracy definitions, a three-axis accuracy evaluation criterion has been proposed in this paper, which could determine pointing and rolling accuracy of a star tracker directly. Experimental measurements confirm that this method is effective and convenient to implement. Such a measurement environment is close to the in-orbit conditions and it can satisfy the stringent requirement for high-accuracy star trackers. PMID:26948412

  10. Accuracy of needle position measurements using fiber Bragg gratings.

    PubMed

    Henken, Kirsten; Van Gerwen, Dennis; Dankelman, Jenny; Van Den Dobbelsteen, John

    2012-11-01

    Accurate placement of the needle tip is essential in percutaneous therapies such as radiofrequency ablation (RFA) of liver tumors. Use of a robotic system for navigating the needle could improve the targeting accuracy. Real-time information on the needle tip position is needed, since a needle deflects during insertion in tissue. Needle shape can be reconstructed based on strain measurements within the needle. In the current experiment we determined the accuracy with which the needle tip position can be derived from strain measurements using Fiber Bragg Gratings (FBGs). Three glass fibers equipped with two FBGs each were incorporated in a needle. The needle was clamped at one end and deformed by applying static radial displacements at one or two locations. The FBG output was used for offline estimation of the needle shape and tip position. During deflections of the needle tip up to 12.5 mm, the tip position was estimated with a mean accuracy of 0.89 mm (std 0.42 mm). Adding a second deflection resulted in an error of 1.32 mm (std 0.48 mm). This accuracy is appropriate for applications such as RFA of liver tumors. The results further show that the accuracy can be improved by optimizing the placement of FBGs. PMID:22455615

  11. New consistency tests for high-accuracy measurements of X-ray mass attenuation coefficients by the X-ray extended-range technique

    SciTech Connect

    Chantler, C.T.; Islam, M.T.; Rae, N.A.; Tran, C.Q.; Glover, J.L.; Barnea, Z.

    2012-09-25

    An extension of the X-ray extended-range technique is described for measuring X-ray mass attenuation coefficients by introducing absolute measurement of a number of foils - the multiple independent foil technique. Illustrating the technique with the results of measurements for gold in the 38-50 keV energy range, it is shown that its use enables selection of the most uniform and well defined of available foils, leading to more accurate measurements; it allows one to test the consistency of independently measured absolute values of the mass attenuation coefficient with those obtained by the thickness transfer method; and it tests the linearity of the response of the counter and counting chain throughout the range of X-ray intensities encountered in a given experiment. In light of the results for gold, the strategy to be ideally employed in measuring absolute X-ray mass attenuation coefficients, X-ray absorption fine structure and related quantities is discussed.

  12. A Comparison of Bias in Four Measures of Monitoring Accuracy

    ERIC Educational Resources Information Center

    Kuch, Frederick H.

    2012-01-01

    Typically in calibration research, subjects perform a task and make a judgment about the success of the task. Accurate findings help subjects improve self-calibration. In addition, researchers rely on the accuracy of findings to make inferences about underlying metacognitive processes. Consequently, it is important that the measures used to assess…

  13. SUPERFUND GROUND WATER ISSUE - ACCURACY OF DEPTH TO WATER MEASUREMENTS

    EPA Science Inventory

    Accuracy of depth to water measurements is an issue identified by the Forum as a concern of Superfund decision-makers as they attempt to determine directions of ground-water flow, areas of recharge of discharge, the hydraulic characteristics of aquifers, or the effects of manmade...

  14. Portable, high intensity isotopic neutron source provides increased experimental accuracy

    NASA Technical Reports Server (NTRS)

    Mohr, W. C.; Stewart, D. C.; Wahlgren, M. A.

    1968-01-01

    Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy.

  15. Calculation and accuracy of ERBE scanner measurement locations

    NASA Technical Reports Server (NTRS)

    Hoffman, Lawrence H.; Weaver, William L.; Kibler, James F.

    1987-01-01

    The Earth Radiation Budget Experiment (ERBE) uses scanning radiometers to measure shortwave and longwave components of the Earth's radiation field at about 40 km resolution. It is essential that these measurements be accurately located at the top of the Earth's atmosphere so they can be properly interpreted by users of the data. Before the launch of the ERBE instrument sets, a substantial emphasis was placed on understanding all factors which influence the determination of measurement locations and properly modeling those factors in the data processing system. After the launch of ERBE instruments on the Earth Radiation Budget Satellite and NOAA 9 spacecraft in 1984, a coastline projection method was developed to assess the accuracy of the algorithms and data used in the location calculations. Using inflight scanner data and the coastline detection technique, the measurement location errors are found to be smaller than the resolution of the scanner instruments. This accuracy is well within the required location knowledge for useful science analysis.

  16. Use of Chemical Inventory Accuracy Measurements as Leading Indicators

    SciTech Connect

    Quigley, David; Freshwater, David; Alnajjar, Mikhail S.; Siegel, Dina; Kuntamukkula, Murty; Simmons, Fred

    2012-05-15

    Chemical safety and lifecycle management (CSLM) is a process that involves managing chemicals and chemical information from the moment someone begins to order a chemical and lasts through final disposition(1). Central to CSLM is tracking data associated with chemicals which, for the purposes of this paper, is termed the chemical inventory. Examples of data that could be tracked include chemical identity, location, quantity, date procured, container type, and physical state. The reason why so much data is tracked is that the chemical inventory supports many functions. These functions include emergency management, which depends upon the data to more effectively plan for, and respond to, chemical accidents; environmental management that uses inventory information to aid in the generation of various federally-mandated and other regulatory reports; and chemical management that uses the information to increase the efficiency and safety with which chemicals are stored and utilized. All of the benefits of having an inventory are predicated upon having an inventory that is reasonably accurate. Because of the importance of ensuring one's chemical inventory is accurate, many have become concerned about measuring inventory accuracy. But beyond providing a measure of confidence in information gleaned from the inventory, does the inventory accuracy measurement provide any additional function? The answer is 'Yes'. It provides valuable information that can be used as a leading indicator to gauge the health of a chemical management system. In this paper, we will discuss: (1) what properties make leading indicators effective, (2) how chemical inventories can be used as a leading indicator, (3) how chemical inventory accuracy can be measured, what levels of accuracies should realistically be expected in a healthy system, and (4) what a subpar inventory accuracy measurement portends.

  17. USE OF CHEMICAL INVENTORY ACCURACY MEASUREMENTS AS LEADING INDICATORS

    SciTech Connect

    Kuntamukkula, M.

    2011-02-10

    Chemical safety and lifecycle management (CSLM) is a process that involves managing chemicals and chemical information from the moment someone begins to order a chemical and lasts through final disposition(1). Central to CSLM is tracking data associated with chemicals which, for the purposes of this paper, is termed the chemical inventory. Examples of data that could be tracked include chemical identity, location, quantity, date procured, container type, and physical state. The reason why so much data is tracked is that the chemical inventory supports many functions. These functions include emergency management, which depends upon the data to more effectively plan for, and respond to, chemical accidents; environmental management that uses inventory information to aid in the generation of various federally-mandated and other regulatory reports; and chemical management that uses the information to increase the efficiency and safety with which chemicals are stored and utilized. All of the benefits of having an inventory are predicated upon having an inventory that is reasonably accurate. Because of the importance of ensuring one's chemical inventory is accurate, many have become concerned about measuring inventory accuracy. But beyond providing a measure of confidence in information gleaned from the inventory, does the inventory accuracy measurement provide any additional function? The answer is 'Yes'. It provides valuable information that can be used as a leading indicator to gauge the health of a chemical management system. In this paper, we will discuss: what properties make leading indicators effective, how chemical inventories can be used as a leading indicator, how chemical inventory accuracy can be measured, what levels of accuracies should realistically be expected in a healthy system, and what a subpar inventory accuracy measurement portends.

  18. Accuracy and Usefulness of the HEDIS Childhood Immunization Measures

    PubMed Central

    Solomon, Barry S.; Kim, Julia M.; Miller, Marlene R.

    2012-01-01

    OBJECTIVE: With the use of Centers for Disease Control and Prevention (CDC) immunization recommendations as the gold standard, our objectives were to measure the accuracy (“is this child up-to-date on immunizations?”) and usefulness (“is this child due for catch-up immunizations?”) of the Healthcare Effectiveness Data and Information Set (HEDIS) childhood immunization measures. METHODS: For children aged 24 to 35 months from the 2009 National Immunization Survey, we assessed the accuracy and usefulness of the HEDIS childhood immunization measures for 6 individual immunizations and a composite. RESULTS: A total of 12 096 children met all inclusion criteria and composed the study sample. The HEDIS measures had >90% accuracy when compared with the CDC gold standard for each of the 6 immunizations (range, 94.3%–99.7%) and the composite (93.8%). The HEDIS measure was least accurate for hepatitis B and pneumococcal conjugate immunizations. The proportion of children for which the HEDIS measure yielded a nonuseful result (ie, an incorrect answer to the question, “is this child due for catch-up immunization?”) ranged from 0.33% (varicella) to 5.96% (pneumococcal conjugate). The most important predictor of HEDIS measure accuracy and usefulness was the CDC-recommended number of immunizations due at age 2 years; children with zero or all immunizations due were the most likely to be correctly classified. CONCLUSIONS: HEDIS childhood immunization measures are, on the whole, accurate and useful. Certain immunizations (eg, hepatitis B, pneumococcal conjugate) and children (eg, those with a single overdue immunization), however, are more prone to HEDIS misclassification. PMID:22451701

  19. The Accuracy of Point-of-Care Glucose Measurements

    PubMed Central

    Rebel, Annette; Rice, Mark A.; Fahy, Brenda G.

    2012-01-01

    Control of blood glucose (BG) in an acceptable range is a major therapy target for diabetes patients in both the hospital and outpatient environments. This review focuses on the state of point-of-care (POC) glucose monitoring and the accuracy of the measurement devices. The accuracy of the POC glucose monitor depends on device methodology and other factors, including sample source and collection and patient characteristics. Patient parameters capable of influencing measurements include variations in pH, blood oxygen, hematocrit, changes in microcirculation, and vasopressor therapy. These elements alone or when combined can significantly impact BG measurement accuracy with POC glucose monitoring devices (POCGMDs). In general, currently available POCGMDs exhibit the greatest accuracy within the range of physiological glucose levels but become less reliable at the lower and higher ranges of BG levels. This issue raises serious safety concerns and the importance of understanding the limitations of POCGMDs. This review will discuss potential interferences and shortcomings of the current POCGMDs and stress when these may impact the reliability of POCGMDs for clinical decision-making. PMID:22538154

  20. Multi-camera and structured-light vision system (MSVS) for dynamic high-accuracy 3D measurements of railway tunnels.

    PubMed

    Zhan, Dong; Yu, Long; Xiao, Jian; Chen, Tanglong

    2015-01-01

    Railway tunnel 3D clearance inspection is critical to guaranteeing railway operation safety. However, it is a challenge to inspect railway tunnel 3D clearance using a vision system, because both the spatial range and field of view (FOV) of such measurements are quite large. This paper summarizes our work on dynamic railway tunnel 3D clearance inspection based on a multi-camera and structured-light vision system (MSVS). First, the configuration of the MSVS is described. Then, the global calibration for the MSVS is discussed in detail. The onboard vision system is mounted on a dedicated vehicle and is expected to suffer from multiple degrees of freedom vibrations brought about by the running vehicle. Any small vibration can result in substantial measurement errors. In order to overcome this problem, a vehicle motion deviation rectifying method is investigated. Experiments using the vision inspection system are conducted with satisfactory online measurement results. PMID:25875190

  1. High accuracy LADAR scene projector calibration sensor development

    NASA Astrophysics Data System (ADS)

    Kim, Hajin J.; Cornell, Michael C.; Naumann, Charles B.; Bowden, Mark H.

    2008-04-01

    A sensor system for the characterization of infrared laser radar scene projectors has been developed. Available sensor systems do not provide sufficient range resolution to evaluate the high precision LADAR projector systems developed by the U.S. Army Research, Development and Engineering Command (RDECOM) Aviation and Missile Research, Development and Engineering Center (AMRDEC). With timing precision capability to a fraction of a nanosecond, it can confirm the accuracy of simulated return pulses from a nominal range of up to 6.5 km to a resolution of 4cm. Increased range can be achieved through firmware reconfiguration. Two independent amplitude triggers measure both rise and fall time providing a judgment of pulse shape and allowing estimation of the contained energy. Each return channel can measure up to 32 returns per trigger characterizing each return pulse independently. Currently efforts include extending the capability to 8 channels. This paper outlines the development, testing, capabilities and limitations of this new sensor system.

  2. High Accuracy in Silico Sulfotransferase Models*

    PubMed Central

    Cook, Ian; Wang, Ting; Falany, Charles N.; Leyh, Thomas S.

    2013-01-01

    Predicting enzymatic behavior in silico is an integral part of our efforts to understand biology. Hundreds of millions of compounds lie in targeted in silico libraries waiting for their metabolic potential to be discovered. In silico “enzymes” capable of accurately determining whether compounds can inhibit or react is often the missing piece in this endeavor. This problem has now been solved for the cytosolic sulfotransferases (SULTs). SULTs regulate the bioactivities of thousands of compounds—endogenous metabolites, drugs and other xenobiotics—by transferring the sulfuryl moiety (SO3) from 3′-phosphoadenosine 5′-phosphosulfate to the hydroxyls and primary amines of these acceptors. SULT1A1 and 2A1 catalyze the majority of sulfation that occurs during human Phase II metabolism. Here, recent insights into the structure and dynamics of SULT binding and reactivity are incorporated into in silico models of 1A1 and 2A1 that are used to identify substrates and inhibitors in a structurally diverse set of 1,455 high value compounds: the FDA-approved small molecule drugs. The SULT1A1 models predict 76 substrates. Of these, 53 were known substrates. Of the remaining 23, 21 were tested, and all were sulfated. The SULT2A1 models predict 22 substrates, 14 of which are known substrates. Of the remaining 8, 4 were tested, and all are substrates. The models proved to be 100% accurate in identifying substrates and made no false predictions at Kd thresholds of 100 μm. In total, 23 “new” drug substrates were identified, and new linkages to drug inhibitors are predicted. It now appears to be possible to accurately predict Phase II sulfonation in silico. PMID:24129576

  3. Portable and autonomous X-ray equipment for in-situ threat materials identification by effective atomic number high-accuracy measurement

    NASA Astrophysics Data System (ADS)

    Iovea, M.; Neagu, M.; Mateiasi, G.; Duliu, O.

    2011-06-01

    A novel portable and autonomous X-ray dual-energy Radioscopy equipment, developed for bomb squad interventions and NDT applications and capable of in-situ digital radiography imaging with measurement of the effective Atomic number of materials (Zeff), is presented. The system consists of a 2D dual-energy X-ray detector based on a rapidly translated linear array, a portable X-ray source and dedicated software running on a laptop or tablet PC. By measurement of the collected x-ray intensities at two different energy spectra, the system can directly compute the material Zeff value for various organic materials contained in the scanned object and then identify them from a database list. The entire system calibration has been obtained using explosive simulants with known Zeff values, the measurement error of Zeffbeing around +/-3.5 % with respect to the reference values. The excellent image resolution and the ability of the automated threat identification algorithm are presented for experiments with a briefcase and a hand-held baggage having various domestic objects and an explosive simulant inside.

  4. Automated electrostatic probe device of high resolution and accuracy

    NASA Astrophysics Data System (ADS)

    Aleiferis, S.; Svarnas, P.

    2014-12-01

    In this work, an automated apparatus for driving single electrostatic probes and acquiring the plasma-related data has been designed and fabricated. The voltage range of the present system is ±110 V with an adjustable voltage step as low as 3 mV. Voltage and current measurements are carried out with high resolution and high accuracy circuits, both based on 16 bit analog-to-digital converters. The code embedded in a micro-controller, schedules the operation of the device and transfers the experimental data to a personal computer. The modular design of the system makes possible its modification and thus increases its adaptability to different plasma setups. Finally, the reliable operation of the entire device is confirmed by tests in Electron Cyclotron Resonance plasma.

  5. Automated electrostatic probe device of high resolution and accuracy

    SciTech Connect

    Aleiferis, S.

    2014-12-15

    In this work, an automated apparatus for driving single electrostatic probes and acquiring the plasma-related data has been designed and fabricated. The voltage range of the present system is ±110 V with an adjustable voltage step as low as 3 mV. Voltage and current measurements are carried out with high resolution and high accuracy circuits, both based on 16 bit analog-to-digital converters. The code embedded in a micro-controller, schedules the operation of the device and transfers the experimental data to a personal computer. The modular design of the system makes possible its modification and thus increases its adaptability to different plasma setups. Finally, the reliable operation of the entire device is confirmed by tests in Electron Cyclotron Resonance plasma.

  6. Effect of temporal resolution on the accuracy of ADCP measurements

    USGS Publications Warehouse

    Gonzalez-Castro, J. A.; Oberg, K.; Duncker, J.J.

    2004-01-01

    The application of acoustic Doppler current profilers (ADCP's) in river flow measurements is promoting a great deal of progress in hydrometry. ADCP's not only require shorter times to collect data than traditional current meters, but also allow streamflow measurements at sites where the use of conventional meters is either very expensive, unsafe, or simply not possible. Moreover, ADCP's seem to offer a means for collecting flow data with spatial and temporal resolutions that cannot be achieved with traditional current-meters. High-resolution data is essential to characterize the mean flow and turbulence structure of streams, which can in turn lead to a better understanding of the hydrodynamic and transport processes in rivers. However, to properly characterize the mean flow and turbulence intensities of stationary flows in natural turbulent boundary layers, velocities need to be sampled over a long-enough time span. The question then arises, how long should velocities be sampled in the flow field to achieve an adequate temporal resolution? Theoretically, since velocities cannot be sampled over an infinitely long time interval, the error due to finite integration time must be considered. This error can be estimated using the integral time scale. The integral time scale is not only a measure of the time interval over which a fluctuating function is correlated with itself but also a measure of the time span over which the function is dependent on itself. This time scale, however, is not a constant but varies spatially in the flow field. In this paper we present an analysis of the effect of the temporal resolution (sampling time span) on the accuracy of ADCP measurements based on the integral time scale. Single ping velocity profiles collected with frequencies of 1 Hz in the Chicago River at Columbus Drive using an uplooking 600 kHz ADCP are used in this analysis. The integral time scale at different depths is estimated based on the autocorrelation function of the

  7. High accuracy EOS experiments using the AWE HELEN laser

    NASA Astrophysics Data System (ADS)

    Rothman, S. D.; Evans, A. M.

    1998-07-01

    A knowledge of a material's equation-of-state (EOS) is essential for hydrodynamic calculations. Although laser experiments investigate the pressure range between those attainable by gas guns (10Mbar) where no other data exist, it is still advantageous to obtain high accuracy data to discriminate between EOS models which have been compared with gas gun and UGT data to a few percent in pressure. The AWE HELEN laser is being used to obtain high pressure Hugoniot data by the impedance match method. Indirect drive generates pressures up to 10Mbar in the aluminium reference material. Shock velocities are obtained by observing the visible light emitted on break-out from the surface of the target using optical streak cameras. Experiments have been performed on copper and brominated plastic. Attention to target fabrication and metrology, diagnostic calibration, shock uniformity and attenuation and data analysis have enabled us to measure shock velocities to an accuracy of ˜1%.

  8. High Accuracy EOS Experiments Using the AWE HELEN Laser.

    NASA Astrophysics Data System (ADS)

    Rothman, S. D.; Evans, A. M.

    1997-07-01

    A knowledge of a material's equation-of-state (EOS) is essential for hydrodynamic calculations. Although laser experiments investigate the pressure range between those attainable by gas guns (10Mbar) where no other data exist, it is still advantageous to obtain high accuracy data to discriminate between EOS models which have been compared with gas gun and UGT data to a few percent in pressure. The AWE HELEN laser is being used to obtain high pressure Hugoniot data by the impedance match method. Indirect drive generates pressures up to 10Mbar in the aluminium reference material. Shock velocities are obtained by observing the visible light emitted on break-out from the surface of the target using optical streak cameras.Experiments have been performed on copper and brominated plastic.Attention to target fabrication and metrology, diagnostic calibration, shock uniformity and attenuation and data analysis have enabled us to measure shock velocities to an accuracy of 1it intact.

  9. Improvement of the high-accuracy 17O(p ,α )14N reaction-rate measurement via the Trojan Horse method for application to 17O nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Sergi, M. L.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Rapisarda, G. G.; Tang, X. D.; Bucher, B.; Couder, M.; Davies, P.; deBoer, R.; Fang, X.; Lamm, L.; Ma, C.; Notani, M.; O'Brien, S.; Roberson, D.; Tan, W.; Wiescher, M.; Irgaziev, B.; Mukhamedzhanov, A.; Mrazek, J.; Kroha, V.

    2015-06-01

    The 17O(p ,α )14N and 17O(p ,γ )18F reactions are of paramount importance for the nucleosynthesis in a number of stellar sites, including red giants (RGs), asymptotic giant branch (AGB) stars, massive stars, and classical novae. In particular, they govern the destruction of 17O and the formation of the short-lived radioisotope 18F, which is of special interest for γ -ray astronomy. At temperatures typical of the above-mentioned astrophysical scenario, T =0.01 -0.1 GK for RG, AGB, and massive stars and T =0.1 -0.4 GK for a classical nova explosion, the 17O(p ,α )14N reaction cross section is dominated by two resonances: one at about ERc m=65 keV above the 18F proton threshold energy, corresponding to the EX=5.673 MeV level in 18F, and another one at ERc m=183 keV (EX=5.786 MeV). We report on the indirect study of the 17O(p ,α )14N reaction via the Trojan Horse method by applying the approach recently developed for extracting the strength of narrow resonance at ultralow energies. The mean value of the strengths obtained in the two measurements was calculated and compared with the direct data available in literature. This value was used as input parameter for reaction-rate determination and its comparison with the result of the direct measurement is also discussed in the light of the electron screening effect.

  10. The adaptive accuracy of flowers: measurement and microevolutionary patterns

    PubMed Central

    Armbruster, W. Scott; Hansen, Thomas F.; Pélabon, Christophe; Pérez-Barrales, Rocío; Maad, Johanne

    2009-01-01

    Background and Aims From Darwin's time onward, biologists have thought about adaptation as evolution toward optimal trait values, but they have not usually assessed the relative importance of the distinct causes of deviations from optima. This problem is investigated here by measuring adaptive inaccuracy (phenotypic deviation from the optimum), using flower pollination as an adaptive system. Methods Adaptive accuracy is shown to have at least three distinct components, two of which are optimality (deviation of the mean from the optimum) and precision (trait variance). We then describe adaptive accuracy of both individuals and populations. Individual inaccuracy comprises the deviation of the genotypic target (the mean phenotype of a genotype grown in a range of environments) from the optimum and the phenotypic variation around that genotypic target (phenotypic imprecision). Population inaccuracy has three basic components: deviation of the population mean from the optimum, variance in the genotypic targets and phenotypic imprecision. In addition, a fourth component is proposed, namely within-population variation in the optimum. These components are directly estimable, have additive relationships, and allow exploration of the causes of adaptive inaccuracy of both individuals and populations. Adaptive accuracy of a sample of flowers is estimated, relating floral phenotypes controlling pollen deposition on pollinators to adaptive optima defined as the site most likely to get pollen onto stigmas (male inaccuracy). Female inaccuracy is defined as the deviation of the position of stigma contact from the expected location of pollen on pollinators. Key Results A surprising amount of variation in estimated accuracy within and among similar species is found. Some of this variation is generated by developmental changes in positions of stigmas or anthers during anthesis (the floral receptive period), which can cause dramatic change in accuracy estimates. There seem to be trends

  11. Optical surface pressure measurements: Accuracy and application field evaluation

    NASA Astrophysics Data System (ADS)

    Bukov, A.; Mosharov, V.; Orlov, A.; Pesetsky, V.; Radchenko, V.; Phonov, S.; Matyash, S.; Kuzmin, M.; Sadovskii, N.

    1994-07-01

    Optical pressure measurement (OPM) is a new pressure measurement method rapidly developed in several aerodynamic research centers: TsAGI (Russia), Boeing, NASA, McDonnell Douglas (all USA), and DLR (Germany). Present level of OPM-method provides its practice as standard experimental method of aerodynamic investigations in definite application fields. Applications of OPM-method are determined mainly by its accuracy. The accuracy of OPM-method is determined by the errors of three following groups: (1) errors of the luminescent pressure sensor (LPS) itself, such as uncompensated temperature influence, photo degradation, temperature and pressure hysteresis, variation of the LPS parameters from point to point on the model surface, etc.; (2) errors of the measurement system, such as noise of the photodetector, nonlinearity and nonuniformity of the photodetector, time and temperature offsets, etc.; and (3) methodological errors, owing to displacement and deformation of the model in an airflow, a contamination of the model surface, scattering of the excitation and luminescent light from the model surface and test section walls, etc. OPM-method allows getting total error of measured pressure not less than 1 percent. This accuracy is enough to visualize the pressure field and allows determining total and distributed aerodynamic loads and solving some problems of local aerodynamic investigations at transonic and supersonic velocities. OPM is less effective at low subsonic velocities (M less than 0.4), and for precise measurements, for example, an airfoil optimization. Current limitations of the OPM-method are discussed on an example of the surface pressure measurements and calculations of the integral loads on the wings of canard-aircraft model. The pressure measurement system and data reduction methods used on these tests are also described.

  12. 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.

  13. The construction of high-accuracy schemes for acoustic equations

    NASA Technical Reports Server (NTRS)

    Tang, Lei; Baeder, James D.

    1995-01-01

    An accuracy analysis of various high order schemes is performed from an interpolation point of view. The analysis indicates that classical high order finite difference schemes, which use polynomial interpolation, hold high accuracy only at nodes and are therefore not suitable for time-dependent problems. Thus, some schemes improve their numerical accuracy within grid cells by the near-minimax approximation method, but their practical significance is degraded by maintaining the same stencil as classical schemes. One-step methods in space discretization, which use piecewise polynomial interpolation and involve data at only two points, can generate a uniform accuracy over the whole grid cell and avoid spurious roots. As a result, they are more accurate and efficient than multistep methods. In particular, the Cubic-Interpolated Psuedoparticle (CIP) scheme is recommended for computational acoustics.

  14. Comparative evaluation of ultrasound scanner accuracy in distance measurement

    NASA Astrophysics Data System (ADS)

    Branca, F. P.; Sciuto, S. A.; Scorza, A.

    2012-10-01

    The aim of the present study is to develop and compare two different automatic methods for accuracy evaluation in ultrasound phantom measurements on B-mode images: both of them give as a result the relative error e between measured distances, performed by 14 brand new ultrasound medical scanners, and nominal distances, among nylon wires embedded in a reference test object. The first method is based on a least squares estimation, while the second one applies the mean value of the same distance evaluated at different locations in ultrasound image (same distance method). Results for both of them are proposed and explained.

  15. The delimitation of the workspace accuracy in coordinate measuring technique.

    PubMed

    Swornowski, Pawel

    2011-01-01

    Dimensional measurements based on coordinate metrology are widely used for product verification, process control and dimensional faults root causes diagnostics of various manufacturing processes. In this study, the results of the measuring surface scanning of coordinate measuring machine with the prototype of optoelectronic device have been presented. The presented device is able to determine actual (real) inaccuracy of the CMM in two axes (X, Y). The prototype scanning device is installed in the measuring probe place. The method makes possible scanning with the established accuracy (max. 0.1 µm). A short description of the new method and the device is added, and some initial results are discussed. The results concern the inaccuracy of the CMMs example measuring area. PMID:21370236

  16. Estimation and filtering techniques for high-accuracy GPS applications

    NASA Technical Reports Server (NTRS)

    Lichten, S. M.

    1989-01-01

    Techniques for determination of very precise orbits for satellites of the Global Positioning System (GPS) are currently being studied and demonstrated. These techniques can be used to make cm-accurate measurements of station locations relative to the geocenter, monitor earth orientation over timescales of hours, and provide tropospheric and clock delay calibrations during observations made with deep space radio antennas at sites where the GPS receivers have been collocated. For high-earth orbiters, meter-level knowledge of position will be available from GPS, while at low altitudes, sub-decimeter accuracy will be possible. Estimation of satellite orbits and other parameters such as ground station positions is carried out with a multi-satellite batch sequential pseudo-epoch state process noise filter. Both square-root information filtering (SRIF) and UD-factorized covariance filtering formulations are implemented in the software.

  17. Symmetrizable connection and combined calibration method for accuracy measurement of CMM

    NASA Astrophysics Data System (ADS)

    Fei, Yetai; Xie, Shao-Feng; Chen, Xia-Huai

    1993-09-01

    In this paper, a new method of syrmetrizab1e connection and ciribined calibration is presented based on an analysis of accuracy of the 1Mt The novel measuring principle and succinct mathematical model are described. By experimental ctparison, the correctness and practicability of the method are proved. In order to assess the M,i accuracy and conpensate for errors, all errors should be measured with high accuracy and efficiency. At the same time, a succinct mathematical model should be developed. For this reason seeking an efficient measuring method for the IM1 has all along been an important subject in this field. All currently used measuring methods for the lMv! have their limitations. To remedy such a situation, the synmetrizable connection method is presented. It solves current problems of the M1 accuracy verification.

  18. Measuring the accuracy of agro-environmental indicators.

    PubMed

    Makowski, David; Tichit, Muriel; Guichard, Laurence; Van Keulen, Herman; Beaudoin, Nicolas

    2009-05-01

    Numerous agro-environmental indicators have been developed by agronomists and ecologists during the last 20 years to assess the environmental impact of farmers' practices, and to monitor effects of agro-environmental policies. The objectives of this paper were (i) to measure the accuracy of a wide range of agro-environmental indicators from experimental data and (ii) to discuss the value of different information typically used by these indicators, i.e. information on farmers' practices, and on plant and soil characteristics. Four series of indicators were considered in this paper: indicators of habitat quality for grassland bird species, indicators of risk of disease in oilseed rape crops, indicators of risk of pollution by nitrogen fertilizer, and indicators of weed infestation. Several datasets were used to measure their accuracy in cultivated plots and in grasslands. The sensitivity, specificity, and probability of correctly ranking plots were estimated for each indicator. Our results showed that the indicators had widely varying levels of accuracy. Some show very poor performance and had no discriminatory ability. Other indicators were informative and performed better than random decisions. Among the tested indicators, the best ones were those using information on plant characteristics such as grass height, fraction of diseased flowers, or crop yield. The statistical method applied in this paper could support researchers, farm advisers, and decision makers in comparing various indicators. PMID:19128870

  19. Monitoring techniques for high accuracy interference fit assembly processes

    NASA Astrophysics Data System (ADS)

    Liuti, A.; Vedugo, F. Rodriguez; Paone, N.; Ungaro, C.

    2016-06-01

    In the automotive industry, there are many assembly processes that require a high geometric accuracy, in the micrometer range; generally open-loop controllers cannot meet these requirements. This results in an increased defect rate and high production costs. This paper presents an experimental study of interference fit process, aimed to evaluate the aspects which have the most impact on the uncertainty in the final positioning. The press-fitting process considered, consists in a press machine operating with a piezoelectric actuator to press a plug into a sleeve. Plug and sleeve are designed and machined to obtain a known interference fit. Differential displacement and velocity measurements of the plug with respect to the sleeve are measured by a fiber optic differential laser Doppler vibrometer. Different driving signals of the piezo actuator allow to have an insight into the differences between a linear and a pulsating press action. The paper highlights how the press-fit assembly process is characterized by two main phases: the first is an elastic deformation of the plug and sleeve, which produces a reversible displacement, the second is a sliding of the plug with respect to the sleeve, which results in an irreversible displacement and finally realizes the assembly. The simultaneous measurements of the displacement and the force have permitted to define characteristic features in the signal useful to identify the start of the irreversible movement. These indicators could be used to develop a control logic in a press assembly process.

  20. A Monte Carlo Comparison of Measures of Relative and Absolute Monitoring Accuracy

    ERIC Educational Resources Information Center

    Nietfeld, John L.; Enders, Craig K; Schraw, Gregory

    2006-01-01

    Researchers studying monitoring accuracy currently use two different indexes to estimate accuracy: relative accuracy and absolute accuracy. The authors compared the distributional properties of two measures of monitoring accuracy using Monte Carlo procedures that fit within these categories. They manipulated the accuracy of judgments (i.e., chance…

  1. Accuracy, Precision, and Resolution in Strain Measurements on Diffraction Instruments

    NASA Astrophysics Data System (ADS)

    Polvino, Sean M.

    Diffraction stress analysis is a commonly used technique to evaluate the properties and performance of different classes of materials from engineering materials, such as steels and alloys, to electronic materials like Silicon chips. Often to better understand the performance of these materials at operating conditions they are also commonly subjected to elevated temperatures and different loading conditions. The validity of any measurement under these conditions is only as good as the control of the conditions and the accuracy and precision of the instrument being used to measure the properties. What is the accuracy and precision of a typical diffraction system and what is the best way to evaluate these quantities? Is there a way to remove systematic and random errors in the data that are due to problems with the control system used? With the advent of device engineering employing internal stress as a method for increasing performance the measurement of stress from microelectronic structures has become of enhanced importance. X-ray diffraction provides an ideal method for measuring these small areas without the need for modifying the sample and possibly changing the strain state. Micro and nano diffraction experiments on Silicon-on-Insulator samples revealed changes to the material under investigation and raised significant concerns about the usefulness of these techniques. This damage process and the application of micro and nano diffraction is discussed.

  2. Algorithm for recognition and measurement position of pitches on invar scale with submicron accuracy

    NASA Astrophysics Data System (ADS)

    Lashmanov, Oleg; Korotaev, Valery

    2015-05-01

    High precision optical encoders are used for many high end computerized numerical control machines. Main requirement for such systems are accuracy and time of measurement, therefore image processing are often performed by FPGA or DSP. This article will describe image processing algorithm for detecting and measuring pitch position on invar scale, which can be easily implemented on specified target hardware. The paper proposed to use a one-dimensional approach for pitch recognition and measure its position on the image. This algorithm is well suited for implementation on FPGA and DSP and provide accuracy 0.07 pixel.

  3. Stabilized high-accuracy optical tracking system (SHOTS)

    NASA Astrophysics Data System (ADS)

    Ruffatto, Donald; Brown, H. Donald; Pohle, Richard H.; Reiley, Michael F.; Haddock, Delmar D.

    2001-08-01

    This paper describes an 0.75 meter aperture, Stabilized High-accuracy Optical Tracking System (SHOTS), two of which are being developed by Textron Systems Corporation, under contract to the Navy's Space and Naval Warfare Systems Center, San Diego (SPAWAR-SD). The SHOTS design is optimized to meet the requirements of the Navy's Theater Ballistic Missile Defense (TBMD) testing program being conducted at the Kauai Pacific Missile Range Facility (PMRF). The SHOTS utilizes a high-precision, GPS aided inertial navigation unit (INU) coupled with a 3-axis, rate gyro stabilized mount which allows precision pointing to be achieved on either land or sea-based platforms. The SHOTS mount control system architecture, acquisition, tracking and pointing (ATP) functionality and methodology which allows the system to meet the TBMD mission data collection requirements are discussed. High frame rate visible and MWIR sensors are incorporated into the system design to provide the capability of capturing short duration events, e.g., missile-target intercepts. These sensors along with the supporting high speed data acquisition, recording and control subsystems are described. Simulations of the SHOTS imaging performance in TBMD measurement scenarios are presented along with an example of the image improvement being achieved with post-processing image reconstruction algorithms.

  4. On accuracy of holographic shape measurement method with spherical wave illumination

    NASA Astrophysics Data System (ADS)

    Mikuła, Marta; Kozacki, Tomasz; Kostencka, Julianna; LiŻewski, Kamil; Józwik, Michał

    2014-11-01

    This paper presents the study on the accuracy of topography measurement of high numerical aperture focusing microobjects in digital holographic microscope setup. The system works in reflective configuration with spherical wave illumination. For numerical reconstruction of topography of high NA focusing microobjects we are using two algorithms: Thin Element Approximation (TEA) and Spherical Local Ray Approximation (SLRA). In this paper we show comparison of the accuracy of topography reconstruction results using these algorithms. We show superiority of SLRA method. However, to obtain accurate results two experimental conditions have to be determined: the position of point source (PS) and imaging reference plane (IRP).Therefore we simulate the effect of point source (PS) and imaging reference plane (IRP) position on the accuracy of shape calculation. Moreover we evaluate accuracy of determination of location of PS and IRP and finally present measurement result of microlens object.

  5. Accuracy of real time radiography burning rate measurement

    NASA Astrophysics Data System (ADS)

    Olaniyi, Bisola

    The design of a solid propellant rocket motor requires the determination of a propellant's burning-rate and its dependency upon environmental parameters. The requirement that the burning-rate be physically measured, establishes the need for methods and equipment to obtain such data. A literature review reveals that no measurement has provided the desired burning rate accuracy. In the current study, flash x-ray modeling and digitized film-density data were employed to predict motor-port area to length ratio. The pre-fired port-areas and base burning rate were within 2.5% and 1.2% of their known values, respectively. To verify the accuracy of the method, a continuous x-ray and a solid propellant rocket motor model (Plexiglas cylinder) were used. The solid propellant motor model was translated laterally through a real-time radiography system at different speeds simulating different burning rates. X-ray images were captured and the burning-rate was then determined. The measured burning rate was within 1.65% of the known values.

  6. Scatterometry measurement precision and accuracy below 70 nm

    NASA Astrophysics Data System (ADS)

    Sendelbach, Matthew; Archie, Charles N.

    2003-05-01

    Scatterometry is a contender for various measurement applications where structure widths and heights can be significantly smaller than 70 nm within one or two ITRS generations. For example, feedforward process control in the post-lithography transistor gate formation is being actively pursued by a number of RIE tool manufacturers. Several commercial forms of scatterometry are available or under development which promise to provide satisfactory performance in this regime. Scatterometry, as commercially practiced today, involves analyzing the zeroth order reflected light from a grating of lines. Normal incidence spectroscopic reflectometry, 2-theta fixed-wavelength ellipsometry, and spectroscopic ellipsometry are among the optical techniques, while library based spectra matching and realtime regression are among the analysis techniques. All these commercial forms will find accurate and precise measurement a challenge when the material constituting the critical structure approaches a very small volume. Equally challenging is executing an evaluation methodology that first determines the true properties (critical dimensions and materials) of semiconductor wafer artifacts and then compares measurement performance of several scatterometers. How well do scatterometers track process induced changes in bottom CD and sidewall profile? This paper introduces a general 3D metrology assessment methodology and reports upon work involving sub-70 nm structures and several scatterometers. The methodology combines results from multiple metrologies (CD-SEM, CD-AFM, TEM, and XSEM) to form a Reference Measurement System (RMS). The methodology determines how well the scatterometry measurement tracks critical structure changes even in the presence of other noncritical changes that take place at the same time; these are key components of accuracy. Because the assessment rewards scatterometers that measure with good precision (reproducibility) and good accuracy, the most precise

  7. Accuracy of MRI-based Magnetic Susceptibility Measurements

    NASA Astrophysics Data System (ADS)

    Russek, Stephen; Erdevig, Hannah; Keenan, Kathryn; Stupic, Karl

    Magnetic Resonance Imaging (MRI) is increasingly used to map tissue susceptibility to identify microbleeds associated with brain injury and pathologic iron deposits associated with neurologic diseases such as Parkinson's and Alzheimer's disease. Field distortions with a resolution of a few parts per billion can be measured using MRI phase maps. The field distortion map can be inverted to obtain a quantitative susceptibility map. To determine the accuracy of MRI-based susceptibility measurements, a set of phantoms with paramagnetic salts and nano-iron gels were fabricated. The shapes and orientations of features were varied. Measured susceptibility of 1.0 mM GdCl3 solution in water as a function of temperature agreed well with the theoretical predictions, assuming Gd+3 is spin 7/2. The MRI susceptibility measurements were compared with SQUID magnetometry. The paramagnetic susceptibility sits on top of the much larger diamagnetic susceptibility of water (-9.04 x 10-6), which leads to errors in the SQUID measurements. To extract out the paramagnetic contribution using standard magnetometry, measurements must be made down to low temperature (2K). MRI-based susceptometry is shown to be as or more accurate than standard magnetometry and susceptometry techniques.

  8. Is accuracy of serum free light chain measurement achievable?

    PubMed

    Jacobs, Joannes F M; Tate, Jillian R; Merlini, Giampaolo

    2016-06-01

    The serum free light chain (FLC) assay has proven to be an important complementary test in the management of patients with monoclonal gammopathies. The serum FLC assay has value for patients with plasma cell disorders in the context of screening and diagnosis, prognostic stratification, and quantitative monitoring. Nonetheless, serum FLC measurements have analytical limitations which give rise to differences in FLC reporting depending on which FLC assay and analytical platform is used. As the FLC measurements are incorporated in the International Myeloma Working Group guidelines for the evaluation and management of plasma cell dyscrasias, this may directly affect clinical decisions. As new certified methods for serum FLC assays emerge, the need to harmonise patient FLC results becomes increasingly important. In this opinion paper we provide an overview of the current lack of accuracy and harmonisation in serum FLC measurements. The clinical consequence of non-harmonized FLC measurements is that an individual patient may or may not meet certain diagnostic, prognostic, or response criteria, depending on which FLC assay and platform is used. We further discuss whether standardisation of serum FLC measurements is feasible and provide an overview of the steps needed to be taken towards harmonisation of FLC measurements. PMID:26641970

  9. Ultrafast High Accuracy PCRTM_SOLAR Model for Cloudy Atmosphere

    NASA Technical Reports Server (NTRS)

    Yang, Qiguang; Liu, Xu; Wu, Wan; Yang, Ping; Wang, Chenxi

    2015-01-01

    An ultrafast high accuracy PCRTM_SOLAR model is developed based on PCA compression and principal component-based radiative transfer model (PCRTM). A fast algorithm for simulation of multi-scattering properties of cloud and/or aerosols is integrated into the fast infrared PCRTM. We completed radiance simulation and training for instruments, such as IASI, AIRS, CrIS, NASTI and SHIS, under diverse conditions. The new model is 5 orders faster than 52-stream DISORT with very high accuracy for cloudy sky radiative transfer simulation. It is suitable for hyperspectral remote data assimilation and cloudy sky retrievals.

  10. Calibration of GPS based high accuracy speed meter for vehicles

    NASA Astrophysics Data System (ADS)

    Bai, Yin; Sun, Qiao; Du, Lei; Yu, Mei; Bai, Jie

    2015-02-01

    GPS based high accuracy speed meter for vehicles is a special type of GPS speed meter which uses Doppler Demodulation of GPS signals to calculate the speed of a moving target. It is increasingly used as reference equipment in the field of traffic speed measurement, but acknowledged standard calibration methods are still lacking. To solve this problem, this paper presents the set-ups of simulated calibration, field test signal replay calibration, and in-field test comparison with an optical sensor based non-contact speed meter. All the experiments were carried out on particular speed values in the range of (40-180) km/h with the same GPS speed meter. The speed measurement errors of simulated calibration fall in the range of +/-0.1 km/h or +/-0.1%, with uncertainties smaller than 0.02% (k=2). The errors of replay calibration fall in the range of +/-0.1% with uncertainties smaller than 0.10% (k=2). The calibration results justify the effectiveness of the two methods. The relative deviations of the GPS speed meter from the optical sensor based noncontact speed meter fall in the range of +/-0.3%, which validates the use of GPS speed meter as reference instruments. The results of this research can provide technical basis for the establishment of internationally standard calibration methods of GPS speed meters, and thus ensures the legal status of GPS speed meters as reference equipment in the field of traffic speed metrology.

  11. SU-E-T-223: Investigation of the Accuracy of Two-Dimensional Dose Distributions Measurement From High-Dose-Rate Brachytherapy Ir-192 Source Using Multiple-Diode-Array Detector (MapCheck2)

    SciTech Connect

    Taguenang, J; De La Fuente, T Herman; Ahmad, S; Ali, I

    2014-06-01

    Purpose: To investigate the dosimetric accuracy of multiple-diode-array detector (Mapcheck2) for high-dose-rate brachytherapy Ir-192 source. The two-dimensional (2D) dose distributions measured with MapCheck2 were validated with EBT2 Gafchromic film measurement and AAPM task-group- 43 (TG-43) modeling. Methods: 2D-dose distributions from Ir-192 source were measured with MapCheck2 and EBT2-films. MapCheck2 response was corrected for effects: directional dependence, diode and phantom heterogeneity. Optical density growth of the film was controlled by synchronized scanning of the film exposed to Ir-192 and calibration films exposed to 6 MV linac beams. Similarly, MapCheck2 response was calibrated to dose using 6 MV beams. An empirical model was developed for the dose distributions measured with Mapcheck2 that considered directional, diode and phantom heterogeneity corrections. The dose deposited in solid-state-detectors was modeled using a cavity theory model for the diode. This model was then validated with measurements using EBT2-films and calculations with TG-43. Results: The response of MapCheck2 has been corrected for different effects including: (a) directional dependence of 0–20% over angular range 0o–90o, (b) phantom heterogeneity (3%) and (c) diode heterogeneity (9%). The corrected dose distributions measured with MapCheck2 agreed well with the measured dose distributions from EBT2-film and with calculations using TG-43 within 5% over a wide range of dose levels and rates. The advantages of MapCheck2 include less noisy, linear and stable response compared with film. The response of MapCheck2 exposed to 192Ir-source showed no energy dependence similar to its response to MV energy beam. Detection spatial-resolution of individual diodes was 0.8×0.8 mm2, however, 2DMapCheck2 resolution is limited by distance between diodes (7.07 mm). Conclusion: The dose distribution measured with MapCheck2 agreed well within 5% with that measured using EBT2-films; and

  12. Compact and high-accuracy RF MEMS capacitive series devices

    NASA Astrophysics Data System (ADS)

    Rottenberg, Xavier; Nauwelaers, Bart; De Raedt, Walter; Tilmans, Harrie A. C.

    2005-01-01

    MEMS technology is presented as a promising technology to realize high Q variable capacitors and RF switches with high performance and with high levels of integration. These devices are key elements for systems like phase shifters, tunable filters and matching networks. However, the reliability and the yield of the RF MEMS devices remain the key limiting factors holding the MEMS technology from spreading in the industrial applications. From a RF designer's point of view, reliability and yield are closely related to the accuracy of the definition of the up- and down-state capacitances of the devices. In this paper, we propose a novel compact series capacitive structure with improved predictability and RF performance. The new design mimics a clamped-clamped bridge to lower its sensitivity to the process-induced stress gradient in the up-state. The shape of the device and its consequent parameters, e.g. up- and down-capacitances, are thus more accurately defined even in presence of non-ideal clamping conditions. Unlike the series switchable capacitors with transverse restraining bridge, the novel device does not suffer from high frequency parasitic resonances. Finally, the novel device implements the floating top metal. This allows accurately defining the down-state capacitance of the design at will. Boosted series capacitive switches with inline-restrained cantilever beams have been realized and measured. The isolation is better than 20dB until 1GHz without optimization. The insertion loss in the down-state is better than 0.2dB in the range 1-20GHz. It further slowly and continuously decays to reach 0.4dB at 40GHz without any resonances.

  13. Theoferometer for High Accuracy Optical Alignment and Metrology

    NASA Technical Reports Server (NTRS)

    Toland, Ronald; Leviton, Doug; Koterba, Seth

    2004-01-01

    The accurate measurement of the orientation of optical parts and systems is a pressing problem for upcoming space missions, such as stellar interferometers, requiring the knowledge and maintenance of positions to the sub-arcsecond level. Theodolites, the devices commonly used to make these measurements, cannot provide the needed level of accuracy. This paper describes the design, construction, and testing of an interferometer system to fill the widening gap between future requirements and current capabilities. A Twyman-Green interferometer mounted on a 2 degree of freedom rotation stage is able to obtain sub-arcsecond, gravity-referenced tilt measurements of a sample alignment cube. Dubbed a 'theoferometer,' this device offers greater ease-of-use, accuracy, and repeatability than conventional methods, making it a suitable 21st-century replacement for the theodolite.

  14. The Accuracy of Radio Interferometric Measurements of Earth Rotation

    NASA Technical Reports Server (NTRS)

    Eubanks, T. M.; Steppe, J. A.; Spieth, M. A.

    1985-01-01

    The accuracy of very long base interferometry earth rotation (UT1) measurements is examined by intercomparing TEMPO and POLARIS data for 1982 and the first half of 1983. None of these data are simultaneous, and so a proper intercomparison requires accounting for the scatter introduced by the rapid, unpredictable, UT1 variations driven by exchanges of angular momentum with the atmosphere. A statistical model of these variations, based on meteorological estimates of the Atmospheric Angular Momentum is derived, and the optimal linear (Kalman) smoother for this model is constructed. The scatter between smoothed and independent raw data is consistent with the residual formal errors, which do not depend upon the actual scatter of the UT1 data. This represents the first time that an accurate prediction of the scatter between UT1 data sets were possible.

  15. Accuracy of wind measurements using an airborne Doppler lidar

    NASA Technical Reports Server (NTRS)

    Carroll, J. J.

    1986-01-01

    Simulated wind fields and lidar data are used to evaluate two sources of airborne wind measurement error. The system is sensitive to ground speed and track angle errors, with accuracy required of the angle to within 0.2 degrees and of the speed to within 1 knot, if the recovered wind field is to be within five percent of the correct direction and 10 percent of the correct speed. It is found that errors in recovered wind speed and direction are dependent on wind direction relative to the flight path. Recovery of accurate wind fields from nonsimultaneous sampling errors requires that the lidar data be displaced to account for advection so that the intersections are defined by air parcels rather than fixed points in space.

  16. CO2, CO and CH4 measurements from the NOAA Earth System Research Laboratory's Tall Tower Greenhouse Gas Observing Network: instrumentation, uncertainty analysis and recommendations for future high-accuracy greenhouse gas monitoring efforts

    NASA Astrophysics Data System (ADS)

    Andrews, A. E.; Kofler, J. D.; Trudeau, M. E.; Williams, J. C.; Neff, D. H.; Masarie, K. A.; Chao, D. Y.; Kitzis, D. R.; Novelli, P. C.; Zhao, C. L.; Dlugokencky, E. J.; Lang, P. M.; Crotwell, M. J.; Fischer, M. L.; Parker, M. J.; Lee, J. T.; Baumann, D. D.; Desai, A. R.; Stanier, C. O.; de Wekker, S. F. J.; Wolfe, D. E.; Munger, J. W.; Tans, P. P.

    2013-02-01

    A robust in situ CO2 and CO analysis system has been developed and deployed at eight sites in the NOAA Earth System Research Laboratory's (ESRL) Tall Tower Greenhouse Gas Observing Network. The network uses very tall (> 300 m) television and radio transmitter towers that provide a convenient platform for mid-boundary layer trace gas sampling. Each analyzer has three sample inlets for profile sampling, and a complete vertical profile is obtained every 15 min. The instrument suite at one site has been augmented with a cavity ring-down spectrometer for measuring CO2 and CH4. The long-term stability of the systems in the field is typically better than 0.1 ppm for CO2, 6 ppb for CO, and 0.5 ppb for CH4, as determined from repeated standard gas measurements. The instrumentation is fully automated and includes sensors for measuring a variety of status parameters, such as temperatures, pressures and flow rates that are inputs for automated alerts and quality control algorithms. These algorithms provide detailed and time-dependent uncertainty estimates for all of the gases and could be adapted to other species or analysis systems. The design emphasizes use of off the shelf parts and modularity to facilitate network operations and ease of maintenance. The systems report high-quality data with > 93% uptime. Recurrent problems and limitations of the current system are discussed along with general recommendations for high accuracy trace-gas monitoring. The network is a key component of the North American Carbon Program and a useful model for future research-grade operational greenhouse gas monitoring efforts.

  17. CO2, CO, and CH4 measurements from tall towers in the NOAA Earth System Research Laboratory's Global Greenhouse Gas Reference Network: instrumentation, uncertainty analysis, and recommendations for future high-accuracy greenhouse gas monitoring efforts

    NASA Astrophysics Data System (ADS)

    Andrews, A. E.; Kofler, J. D.; Trudeau, M. E.; Williams, J. C.; Neff, D. H.; Masarie, K. A.; Chao, D. Y.; Kitzis, D. R.; Novelli, P. C.; Zhao, C. L.; Dlugokencky, E. J.; Lang, P. M.; Crotwell, M. J.; Fischer, M. L.; Parker, M. J.; Lee, J. T.; Baumann, D. D.; Desai, A. R.; Stanier, C. O.; De Wekker, S. F. J.; Wolfe, D. E.; Munger, J. W.; Tans, P. P.

    2014-02-01

    A reliable and precise in situ CO2 and CO analysis system has been developed and deployed at eight sites in the NOAA Earth System Research Laboratory's (ESRL) Global Greenhouse Gas Reference Network. The network uses very tall (> 300 m) television and radio transmitter towers that provide a convenient platform for mid-boundary-layer trace-gas sampling. Each analyzer has three sample inlets for profile sampling, and a complete vertical profile is obtained every 15 min. The instrument suite at one site has been augmented with a cavity ring-down spectrometer for measuring CO2 and CH4. The long-term stability of the systems in the field is typically better than 0.1 ppm for CO2, 6 ppb for CO, and 0.5 ppb for CH4, as determined from repeated standard gas measurements. The instrumentation is fully automated and includes sensors for measuring a variety of status parameters, such as temperatures, pressures, and flow rates, that are inputs for automated alerts and quality control algorithms. Detailed and time-dependent uncertainty estimates have been constructed for all of the gases, and the uncertainty framework could be readily adapted to other species or analysis systems. The design emphasizes use of off-the-shelf parts and modularity to facilitate network operations and ease of maintenance. The systems report high-quality data with > 93% uptime. Recurrent problems and limitations of the current system are discussed along with general recommendations for high-accuracy trace-gas monitoring. The network is a key component of the North American Carbon Program and a useful model for future research-grade operational greenhouse gas monitoring efforts.

  18. Accuracy Improvement on the Measurement of Human-Joint Angles.

    PubMed

    Meng, Dai; Shoepe, Todd; Vejarano, Gustavo

    2016-03-01

    A measurement technique that decreases the root mean square error (RMSE) of measurements of human-joint angles using a personal wireless sensor network is reported. Its operation is based on virtual rotations of wireless sensors worn by the user, and it focuses on the arm, whose position is measured on 5 degree of freedom (DOF). The wireless sensors use inertial magnetic units that measure the alignment of the arm with the earth's gravity and magnetic fields. Due to the biomechanical properties of human tissue (e.g., skin's elasticity), the sensors' orientation is shifted, and this shift affects the accuracy of measurements. In the proposed technique, the change of orientation is first modeled from linear regressions of data collected from 15 participants at different arm positions. Then, out of eight body indices measured with dual-energy X-ray absorptiometry, the percentage of body fat is found to have the greatest correlation with the rate of change in sensors' orientation. This finding enables us to estimate the change in sensors' orientation from the user's body fat percentage. Finally, an algorithm virtually rotates the sensors using quaternion theory with the objective of reducing the error. The proposed technique is validated with experiments on five different participants. In the DOF, whose error decreased the most, the RMSE decreased from 2.20(°) to 0.87(°). This is an improvement of 60%, and in the DOF whose error decreased the least, the RMSE decreased from 1.64(°) to 1.37(°). This is an improvement of 16%. On an average, the RMSE improved by 44%. PMID:25622331

  19. Measurement of Phospholipids May Improve Diagnostic Accuracy in Ovarian Cancer

    PubMed Central

    Davis, Lorelei; Han, Gang; Zhu, Weiwei; Molina, Ashley D.; Arango, Hector; LaPolla, James P.; Hoffman, Mitchell S.; Sellers, Thomas; Kirby, Tyler; Nicosia, Santo V.; Sutphen, Rebecca

    2012-01-01

    Background More than two-thirds of women who undergo surgery for suspected ovarian neoplasm do not have cancer. Our previous results suggest phospholipids as potential biomarkers of ovarian cancer. In this study, we measured the serum levels of multiple phospholipids among women undergoing surgery for suspected ovarian cancer to identify biomarkers that better predict whether an ovarian mass is malignant. Methodology/Principal Findings We obtained serum samples preoperatively from women with suspected ovarian cancer enrolled through a prospective, population-based rapid ascertainment system. Samples were analyzed from all women in whom a diagnosis of epithelial ovarian cancer (EOC) was confirmed and from benign disease cases randomly selected from the remaining (non-EOC) samples. We measured biologically relevant phospholipids using liquid chromatography/electrospray ionization mass spectrometry. We applied a powerful statistical and machine learning approach, Hybrid huberized support vector machine (HH-SVM) to prioritize phospholipids to enter the biomarker models, and used cross-validation to obtain conservative estimates of classification error rates. Results The HH-SVM model using the measurements of specific combinations of phospholipids supplements clinical CA125 measurement and improves diagnostic accuracy. Specifically, the measurement of phospholipids improved sensitivity (identification of cases with preoperative CA125 levels below 35) among two types of cases in which CA125 performance is historically poor - early stage cases and those of mucinous histology. Measurement of phospholipids improved the identification of early stage cases from 65% (based on CA125) to 82%, and mucinous cases from 44% to 88%. Conclusions/Significance Levels of specific serum phospholipids differ between women with ovarian cancer and those with benign conditions. If validated by independent studies in the future, these biomarkers may serve as an adjunct at the time of clinical

  20. Quantitative evaluation of three-dimensional facial scanners measurement accuracy for facial deformity

    NASA Astrophysics Data System (ADS)

    Zhao, Yi-jiao; Xiong, Yu-xue; Sun, Yu-chun; Yang, Hui-fang; Lyu, Pei-jun; Wang, Yong

    2015-07-01

    Objective: To evaluate the measurement accuracy of three-dimensional (3D) facial scanners for facial deformity patients from oral clinic. Methods: 10 patients in different types of facial deformity from oral clinical were included. Three 3D digital face models for each patient were obtained by three facial scanners separately (line laser scanner from Faro for reference, stereophotography scanner from 3dMD and structured light scanner from FaceScan for test). For each patient, registration based on Iterative Closest Point (ICP) algorithm was executed to align two test models (3dMD data & Facescan data) to the reference models (Faro data in high accuracy) respectively. The same boundaries on each pair models (one test and one reference models) were obtained by projection function in Geomagic Stuido 2012 software for trimming overlapping region, then 3D average measurement errors (3D errors) were calculated for each pair models also by the software. Paired t-test analysis was adopted to compare the 3D errors of two test facial scanners (10 data for each group). 3D profile measurement accuracy (3D accuracy) that is integrated embodied by average value and standard deviation of 10 patients' 3D errors were obtained by surveying analysis for each test scanner finally. Results: 3D accuracies of 2 test facial scanners in this study for facial deformity were 0.44+/-0.08 mm and 0.43+/-0.05 mm. The result of structured light scanner was slightly better than stereophotography scanner. No statistical difference between them. Conclusions: Both test facial scanners could meet the accuracy requirement (0.5mm) of 3D facial data acquisition for oral clinic facial deformity patients in this study. Their practical measurement accuracies were all slightly lower than their nominal accuracies.

  1. Accuracy of airspeed measurements and flight calibration procedures

    NASA Technical Reports Server (NTRS)

    Huston, Wilber B

    1948-01-01

    The sources of error that may enter into the measurement of airspeed by pitot-static methods are reviewed in detail together with methods of flight calibration of airspeed installations. Special attention is given to the problem of accurate measurements of airspeed under conditions of high speed and maneuverability required of military airplanes. (author)

  2. Inspection of 3D parts using high accuracy range data

    NASA Astrophysics Data System (ADS)

    Prieto, Flavio; Lepage, Richard; Boulanger, Pierre; Redarce, Tanneguy

    2000-03-01

    The use of a laser range sensor in the 3D part digitalization process for inspection tasks allows very significant improvement in acquisition speed and in 3D measurement points density but does not equal the accuracy obtained with a coordinate measuring machine (CMM). Inspection consists in verifying the accuracy of a part related to a given set of tolerances. It is thus necessary that the 3D measurements be accurate. In the 3D capture of a part, several sources of error can alter the measured values. So, we have to find and model the most influent parameters affecting the accuracy of the range sensor in the digitalization process. This model is used to produce a sensing plan to acquire completely and accurately the geometry of a part. The sensing plan is composed of the set of viewpoints which defines the exact position and orientation of the camera relative to the part. The 3D cloud obtained from the sensing plan is registered with the CAD model of the part and then segmented according to the different surfaces. Segmentation results are used to check tolerances of the part. By using the noise model, we introduce a dispersion value for each 3D point acquired according to the sensing plan. This value of dispersion is shown as a weight factor in the inspection results.

  3. High accuracy fuel flowmeter. Phase 2C and 3: The mass flowrate calibration of high accuracy fuel flowmeters

    NASA Technical Reports Server (NTRS)

    Craft, D. William

    1992-01-01

    A facility for the precise calibration of mass fuel flowmeters and turbine flowmeters located at AMETEK Aerospace Products Inc., Wilmington, Massachusetts is described. This facility is referred to as the Test and Calibration System (TACS). It is believed to be the most accurate test facility available for the calibration of jet engine fuel density measurement. The product of the volumetric flow rate measurement and the density measurement, results in a true mass flow rate determination. A dual-turbine flowmeter was designed during this program. The dual-turbine flowmeter was calibrated on the TACS to show the characteristics of this type of flowmeter. An angular momentum flowmeter was also calibrated on the TACS to demonstrate the accuracy of a true mass flowmeter having a 'state-of-the-art' design accuracy.

  4. High accuracy fuel flowmeter. Phase 2C and 3: The mass flowrate calibration of high accuracy fuel flowmeters

    NASA Astrophysics Data System (ADS)

    Craft, D. William

    1992-02-01

    A facility for the precise calibration of mass fuel flowmeters and turbine flowmeters located at AMETEK Aerospace Products Inc., Wilmington, Massachusetts is described. This facility is referred to as the Test and Calibration System (TACS). It is believed to be the most accurate test facility available for the calibration of jet engine fuel density measurement. The product of the volumetric flow rate measurement and the density measurement, results in a true mass flow rate determination. A dual-turbine flowmeter was designed during this program. The dual-turbine flowmeter was calibrated on the TACS to show the characteristics of this type of flowmeter. An angular momentum flowmeter was also calibrated on the TACS to demonstrate the accuracy of a true mass flowmeter having a 'state-of-the-art' design accuracy.

  5. Accuracy of Gradient Reconstruction on Grids with High Aspect Ratio

    NASA Technical Reports Server (NTRS)

    Thomas, James

    2008-01-01

    Gradient approximation methods commonly used in unstructured-grid finite-volume schemes intended for solutions of high Reynolds number flow equations are studied comprehensively. The accuracy of gradients within cells and within faces is evaluated systematically for both node-centered and cell-centered formulations. Computational and analytical evaluations are made on a series of high-aspect-ratio grids with different primal elements, including quadrilateral, triangular, and mixed element grids, with and without random perturbations to the mesh. Both rectangular and cylindrical geometries are considered; the latter serves to study the effects of geometric curvature. The study shows that the accuracy of gradient reconstruction on high-aspect-ratio grids is determined by a combination of the grid and the solution. The contributors to the error are identified and approaches to reduce errors are given, including the addition of higher-order terms in the direction of larger mesh spacing. A parameter GAMMA characterizing accuracy on curved high-aspect-ratio grids is discussed and an approximate-mapped-least-square method using a commonly-available distance function is presented; the method provides accurate gradient reconstruction on general grids. The study is intended to be a reference guide accompanying the construction of accurate and efficient methods for high Reynolds number applications

  6. Design of a high linearity and high gain accuracy analog baseband circuit for DAB receiver

    NASA Astrophysics Data System (ADS)

    Li, Ma; Zhigong, Wang; Jian, Xu; Yiqiang, Wu; Junliang, Wang; Mi, Tian; Jianping, Chen

    2015-02-01

    An analog baseband circuit of high linearity and high gain accuracy for a digital audio broadcasting receiver is implemented in a 0.18-μm RFCMOS process. The circuit comprises a 3rd-order active-RC complex filter (CF) and a programmable gain amplifier (PGA). An automatic tuning circuit is also designed to tune the CF's pass band. Instead of the class-A fully differential operational amplifier (FDOPA) adopted in the conventional CF and PGA design, a class-AB FDOPA is specially employed in this circuit to achieve a higher linearity and gain accuracy for its large current swing capability with lower static current consumption. In the PGA circuit, a novel DC offset cancellation technique based on the MOS resistor is introduced to reduce the settling time significantly. A reformative switching network is proposed, which can eliminate the switch resistor's influence on the gain accuracy of the PGA. The measurement result shows the gain range of the circuit is 10-50 dB with a 1-dB step size, and the gain accuracy is less than ±0.3 dB. The OIP3 is 23.3 dBm at the gain of 10 dB. Simulation results show that the settling time is reduced from 100 to 1 ms. The image band rejection is about 40 dB. It only draws 4.5 mA current from a 1.8 V supply voltage.

  7. Accuracy and Repeatability of Refractive Error Measurements by Photorefractometry

    PubMed Central

    Rajavi, Zhale; Sabbaghi, Hamideh; Baghini, Ahmad Shojaei; Yaseri, Mehdi; Sheibani, Koroush; Norouzi, Ghazal

    2015-01-01

    Purpose: To determine the accuracy of photorefraction and autorefraction as compared to cycloautorefraction and to detect the repeatability of photorefraction. Methods: This diagnostic study included the right eyes of 86 children aged 7-12 years. Refractive status was measured using photorefraction (PlusoptiX SO4, GmbH, Nürnberg, Germany) and autorefraction (Topcon RM800, USA) with and without cycloplegia. Photorefraction for each eye was performed three times to assess repeatability. Results: The overall agreement between photorefraction and cycloautorefraction was over 81% for all refractive errors. Photorefractometry had acceptable sensitivity and specificity for myopia and astigmatism. There was no statistically significant difference considering myopia and astigmatism in all comparisons, while the difference was significant for hyperopia using both amblyogenic (P = 0.006) and nonamblyogenic criteria (P = 0.001). A myopic shift of 1.21 diopter (D) and 1.58 D occurred with photorefraction in nonamblyogenic and amblyogenic hyperopia, respectively. Using revised cut-off points of + 1.12 D and + 2.6 D instead of + 2.00 D and + 3.50 D improved the sensitivity of photorefractometry to 84.62% and 69.23%, respectively. The repeatability of photorefraction for measurement of myopia, astigmatism and hyperopia was acceptable (intra-cluster correlation [ICC]: 0.98, 0.94 and 0.77, respectively). Autorefraction results were significantly different from cycloautorefraction in hyperopia (P < 0.0001), but comparable in myopia and astigmatism. Also, noncycloglegic autorefraction results were similar to photorefraction in this study. Conclusion: Although photorefraction was accurate for measurement of myopia and astigmatism, its sensitivity for hyperopia was low which could be improved by considering revised cut-off points. Considering cut-off points, photorefraction can be used as a screening method. PMID:26730305

  8. Accuracy in Dental Medicine, A New Way to Measure Trueness and Precision

    PubMed Central

    Ender, Andreas; Mehl, Albert

    2014-01-01

    Reference scanners are used in dental medicine to verify a lot of procedures. The main interest is to verify impression methods as they serve as a base for dental restorations. The current limitation of many reference scanners is the lack of accuracy scanning large objects like full dental arches, or the limited possibility to assess detailed tooth surfaces. A new reference scanner, based on focus variation scanning technique, was evaluated with regards to highest local and general accuracy. A specific scanning protocol was tested to scan original tooth surface from dental impressions. Also, different model materials were verified. The results showed a high scanning accuracy of the reference scanner with a mean deviation of 5.3 ± 1.1 µm for trueness and 1.6 ± 0.6 µm for precision in case of full arch scans. Current dental impression methods showed much higher deviations (trueness: 20.4 ± 2.2 µm, precision: 12.5 ± 2.5 µm) than the internal scanning accuracy of the reference scanner. Smaller objects like single tooth surface can be scanned with an even higher accuracy, enabling the system to assess erosive and abrasive tooth surface loss. The reference scanner can be used to measure differences for a lot of dental research fields. The different magnification levels combined with a high local and general accuracy can be used to assess changes of single teeth or restorations up to full arch changes. PMID:24836007

  9. Models of Accuracy in Repeated-Measures Designs

    ERIC Educational Resources Information Center

    Dixon, Peter

    2008-01-01

    Accuracy is often analyzed using analysis of variance techniques in which the data are assumed to be normally distributed. However, accuracy data are discrete rather than continuous, and proportion correct are constrained to the range 0-1. Monte Carlo simulations are presented illustrating how this can lead to distortions in the pattern of means.…

  10. 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

  11. 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.

  12. Study of accuracy of precipitation measurements using simulation method

    NASA Astrophysics Data System (ADS)

    Nagy, Zoltán; Lajos, Tamás; Morvai, Krisztián

    2013-04-01

    of wind shield improve the accuracy of precipitation measurements? · Try to find the source of the error that can be detected at tipping bucket raingauge in winter time because of use of heating power? On our poster we would like to present the answers to the questions listed above.

  13. Accuracy and validity of IK4 handheld video keratometer measurements in children

    PubMed Central

    Harvey, Erin M.; Miller, Joseph M.; Schwiegerling, Jim; Clifford-Donaldson, Candice E.; Green, Tina K.; Messer, Dawn H.; Dobson, Velma

    2011-01-01

    The Infant Keratometer (IK4) is a custom handheld instrument that was designed specifically to allow measurement of corneal astigmatism in infants as young as 6 months of age. In this study, accuracy of IK4 measurements using standard toric surfaces was within 0.25 D. Validity measurements obtained in 860 children aged 3–7 years demonstrated slightly higher astigmatism measurements in the IK4 than in the Retinomax K+. Measurement success was 98% using the IK4. The IK4 may prove to be clinically useful for screening children as young as 3 years of age at high risk for corneal astigmatism. PMID:21907130

  14. High Accuracy Monocular SFM and Scale Correction for Autonomous Driving.

    PubMed

    Song, Shiyu; Chandraker, Manmohan; Guest, Clark C

    2016-04-01

    We present a real-time monocular visual odometry system that achieves high accuracy in real-world autonomous driving applications. First, we demonstrate robust monocular SFM that exploits multithreading to handle driving scenes with large motions and rapidly changing imagery. To correct for scale drift, we use known height of the camera from the ground plane. Our second contribution is a novel data-driven mechanism for cue combination that allows highly accurate ground plane estimation by adapting observation covariances of multiple cues, such as sparse feature matching and dense inter-frame stereo, based on their relative confidences inferred from visual data on a per-frame basis. Finally, we demonstrate extensive benchmark performance and comparisons on the challenging KITTI dataset, achieving accuracy comparable to stereo and exceeding prior monocular systems. Our SFM system is optimized to output pose within 50 ms in the worst case, while average case operation is over 30 fps. Our framework also significantly boosts the accuracy of applications like object localization that rely on the ground plane. PMID:26513777

  15. Accuracy of dilution techniques for access flow measurement during hemodialysis.

    PubMed

    Krivitski, N M; MacGibbon, D; Gleed, R D; Dobson, A

    1998-03-01

    Access flow is now widely measured by creating artificial recirculation with the dialysis lines reversed and using dilution methods that sense either ultrasound velocity, electrical impedance, optical, or thermal changes. This study identifies and quantifies factors that influence the accuracy of access flow measurements and recommends ways to reduce these errors. Two major sources of access flow measurement error are identified, arising firstly from the second pass of the indicator by recirculation through the cardiopulmonary system (cardiopulmonary recirculation, CPR), and secondly from changes in venous line blood flow (Qb) and vascular access flow induced by the pressure of venous bolus injections. These errors are considered from theory, by direct measurement of access flow in a sheep model, and by analysis of clinical data. Two extremes for the venous introduction of indicator can be considered in access flow measurements, a slow infusion, which perturbs neither the venous line flow nor access flow but increases the error attributable to the second pass of the indicator by recirculation through cardiopulmonary system, or rapid injection, which eases separation of the second pass of the indicator signal but generates changes in the venous flow and access flow. If CPR is not eliminated, the area added to that of the first pass of indicator ranges up to 40%. Good time resolution could permit the separation of the areas generated by the first and second passage of the indicator. In sheep experiments, injections of 5 or 10 mL into a venous port close to the vascular access caused Qb to change by 20% to 40%. Both the animal experiments and analysis of raw data collected during routine clinical dialysis showed that moving the injection site sufficiently far from the patient, before or into the venous bubble trap, reduced the increase in Qb to only approximately 5% during the critical time when the concentration curve is changing for most tubing brands (Baxter, Belco

  16. High accuracy operon prediction method based on STRING database scores.

    PubMed

    Taboada, Blanca; Verde, Cristina; Merino, Enrique

    2010-07-01

    We present a simple and highly accurate computational method for operon prediction, based on intergenic distances and functional relationships between the protein products of contiguous genes, as defined by STRING database (Jensen,L.J., Kuhn,M., Stark,M., Chaffron,S., Creevey,C., Muller,J., Doerks,T., Julien,P., Roth,A., Simonovic,M. et al. (2009) STRING 8-a global view on proteins and their functional interactions in 630 organisms. Nucleic Acids Res., 37, D412-D416). These two parameters were used to train a neural network on a subset of experimentally characterized Escherichia coli and Bacillus subtilis operons. Our predictive model was successfully tested on the set of experimentally defined operons in E. coli and B. subtilis, with accuracies of 94.6 and 93.3%, respectively. As far as we know, these are the highest accuracies ever obtained for predicting bacterial operons. Furthermore, in order to evaluate the predictable accuracy of our model when using an organism's data set for the training procedure, and a different organism's data set for testing, we repeated the E. coli operon prediction analysis using a neural network trained with B. subtilis data, and a B. subtilis analysis using a neural network trained with E. coli data. Even for these cases, the accuracies reached with our method were outstandingly high, 91.5 and 93%, respectively. These results show the potential use of our method for accurately predicting the operons of any other organism. Our operon predictions for fully-sequenced genomes are available at http://operons.ibt.unam.mx/OperonPredictor/. PMID:20385580

  17. Towards high accuracy calibration of electron backscatter diffraction systems.

    PubMed

    Mingard, Ken; Day, Austin; Maurice, Claire; Quested, Peter

    2011-04-01

    For precise orientation and strain measurements, advanced Electron Backscatter Diffraction (EBSD) techniques require both accurate calibration and reproducible measurement of the system geometry. In many cases the pattern centre (PC) needs to be determined to sub-pixel accuracy. The mechanical insertion/retraction, through the Scanning Electron Microscope (SEM) chamber wall, of the electron sensitive part of modern EBSD detectors also causes alignment and positioning problems and requires frequent monitoring of the PC. Optical alignment and lens distortion issues within the scintillator, lens and charge-coupled device (CCD) camera combination of an EBSD detector need accurate measurement for each individual EBSD system. This paper highlights and quantifies these issues and demonstrates the determination of the pattern centre using a novel shadow-casting technique with a precision of ∼10μm or ∼1/3 CCD pixel. PMID:21396526

  18. Improving the accuracy of smart devices to measure noise exposure.

    PubMed

    Roberts, Benjamin; Kardous, Chucri; Neitzel, Richard

    2016-11-01

    Occupational noise exposure is one of the most frequent hazards present in the workplace; up to 22 million workers have potentially hazardous noise exposures in the U.S. As a result, noise-induced hearing loss is one of the most common occupational injuries in the U.S. Workers in manufacturing, construction, and the military are at the highest risk for hearing loss. Despite the large number of people exposed to high levels of noise at work, many occupations have not been adequately evaluated for noise exposure. The objective of this experiment was to investigate whether or not iOS smartphones and other smart devices (Apple iPhones and iPods) could be used as reliable instruments to measure noise exposures. For this experiment three different types of microphones were tested with a single model of iPod and three generations of iPhones: the internal microphones on the device, a low-end lapel microphone, and a high-end lapel microphone marketed as being compliant with the International Electrotechnical Commission's (IEC) standard for a Class 2-microphone. All possible combinations of microphones and noise measurement applications were tested in a controlled environment using several different levels of pink noise ranging from 60-100 dBA. Results were compared to simultaneous measurements made using a Type 1 sound level measurement system. Analysis of variance and Tukey's honest significant difference (HSD) test were used to determine if the results differed by microphone or noise measurement application. Levels measured with external microphones combined with certain noise measurement applications did not differ significantly from levels measured with the Type 1 sound measurement system. Results showed that it may be possible to use iOS smartphones and smart devices, with specific combinations of measurement applications and calibrated external microphones, to collect reliable, occupational noise exposure data under certain conditions and within the limitations of the

  19. Development of a Small Two Axis Spherical Motor Type Laser Tracker with Submicron Measurement Accuracy

    NASA Astrophysics Data System (ADS)

    Yano, Tomoaki; Takatsuji, Toshiyuki; Osawa, Sonko; Suzuki, Takeo; Motomura, Yoichi; Itabe, Tadao

    Recently, it is in great need for measurement of the three dimensional surface form of the car and the aircraft, the path of the industrial robot and the machine tool, and so on with a high degree of accuracy. We have proposed a novel laser tracking three dimensional position measurement system which can measure the 3D position with submicron accuracy at more than 1[m] by combining the oscillating lever mechanism with the spherical motor. Before making the full system, we made the first and the second prototype spherical motor type laser tracker unit and tested them. The average measurement error of the developed laser tracker 2 is 0.45[μm] and the standard deviation is 0.54[μm], which satisfy the specifications needed for the full system.

  20. Accuracy testing of steel and electric groundwater-level measuring tapes: Test method and in-service tape accuracy

    USGS Publications Warehouse

    Fulford, Janice M.; Clayton, Christopher S.

    2015-01-01

    The calibration device and proposed method were used to calibrate a sample of in-service USGS steel and electric groundwater tapes. The sample of in-service groundwater steel tapes were in relatively good condition. All steel tapes, except one, were accurate to ±0.01 ft per 100 ft over their entire length. One steel tape, which had obvious damage in the first hundred feet, was marginally outside the accuracy of ±0.01 ft per 100 ft by 0.001 ft. The sample of in-service groundwater-level electric tapes were in a range of conditions—from like new, with cosmetic damage, to nonfunctional. The in-service electric tapes did not meet the USGS accuracy recommendation of ±0.01 ft. In-service electric tapes, except for the nonfunctional tape, were accurate to about ±0.03 ft per 100 ft. A comparison of new with in-service electric tapes found that steel-core electric tapes maintained their length and accuracy better than electric tapes without a steel core. The in-service steel tapes could be used as is and achieve USGS accuracy recommendations for groundwater-level measurements. The in-service electric tapes require tape corrections to achieve USGS accuracy recommendations for groundwater-level measurement.

  1. Accuracy and reproducibility of bending stiffness measurements by mechanical response tissue analysis in artificial human ulnas.

    PubMed

    Arnold, Patricia A; Ellerbrock, Emily R; Bowman, Lyn; Loucks, Anne B

    2014-11-01

    Osteoporosis is characterized by reduced bone strength, but no FDA-approved medical device measures bone strength. Bone strength is strongly associated with bone stiffness, but no FDA-approved medical device measures bone stiffness either. Mechanical Response Tissue Analysis (MRTA) is a non-significant risk, non-invasive, radiation-free, vibration analysis technique for making immediate, direct functional measurements of the bending stiffness of long bones in humans in vivo. MRTA has been used for research purposes for more than 20 years, but little has been published about its accuracy. To begin to investigate its accuracy, we compared MRTA measurements of bending stiffness in 39 artificial human ulna bones to measurements made by Quasistatic Mechanical Testing (QMT). In the process, we also quantified the reproducibility (i.e., precision and repeatability) of both methods. MRTA precision (1.0±1.0%) and repeatability (3.1 ± 3.1%) were not as high as those of QMT (0.2 ± 0.2% and 1.3+1.7%, respectively; both p<10(-4)). The relationship between MRTA and QMT measurements of ulna bending stiffness was indistinguishable from the identity line (p=0.44) and paired measurements by the two methods agreed within a 95% confidence interval of ± 5%. If such accuracy can be achieved on real human ulnas in situ, and if the ulna is representative of the appendicular skeleton, MRTA may prove clinically useful. PMID:25261885

  2. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... recording at intervals not to exceed 5 minutes. (4) Flow measurement adaptor (40 CFR part 50, appendix L.... (7) Teflon sample filter, as specified in section 6 of 40 CFR part 50, appendix L (if required). (d... calibration, certification of calibration accuracy, and NIST-traceability (if required) of all...

  3. High-accuracy mass spectrometry for fundamental studies.

    PubMed

    Kluge, H-Jürgen

    2010-01-01

    Mass spectrometry for fundamental studies in metrology and atomic, nuclear and particle physics requires extreme sensitivity and efficiency as well as ultimate resolving power and accuracy. An overview will be given on the global status of high-accuracy mass spectrometry for fundamental physics and metrology. Three quite different examples of modern mass spectrometric experiments in physics are presented: (i) the retardation spectrometer KATRIN at the Forschungszentrum Karlsruhe, employing electrostatic filtering in combination with magnetic-adiabatic collimation-the biggest mass spectrometer for determining the smallest mass, i.e. the mass of the electron anti-neutrino, (ii) the Experimental Cooler-Storage Ring at GSI-a mass spectrometer of medium size, relative to other accelerators, for determining medium-heavy masses and (iii) the Penning trap facility, SHIPTRAP, at GSI-the smallest mass spectrometer for determining the heaviest masses, those of super-heavy elements. Finally, a short view into the future will address the GSI project HITRAP at GSI for fundamental studies with highly-charged ions. PMID:20530821

  4. Researches on High Accuracy Prediction Methods of Earth Orientation Parameters

    NASA Astrophysics Data System (ADS)

    Xu, X. Q.

    2015-09-01

    The Earth rotation reflects the coupling process among the solid Earth, atmosphere, oceans, mantle, and core of the Earth on multiple spatial and temporal scales. The Earth rotation can be described by the Earth's orientation parameters, which are abbreviated as EOP (mainly including two polar motion components PM_X and PM_Y, and variation in the length of day ΔLOD). The EOP is crucial in the transformation between the terrestrial and celestial reference systems, and has important applications in many areas such as the deep space exploration, satellite precise orbit determination, and astrogeodynamics. However, the EOP products obtained by the space geodetic technologies generally delay by several days to two weeks. The growing demands for modern space navigation make high-accuracy EOP prediction be a worthy topic. This thesis is composed of the following three aspects, for the purpose of improving the EOP forecast accuracy. (1) We analyze the relation between the length of the basic data series and the EOP forecast accuracy, and compare the EOP prediction accuracy for the linear autoregressive (AR) model and the nonlinear artificial neural network (ANN) method by performing the least squares (LS) extrapolations. The results show that the high precision forecast of EOP can be realized by appropriate selection of the basic data series length according to the required time span of EOP prediction: for short-term prediction, the basic data series should be shorter, while for the long-term prediction, the series should be longer. The analysis also showed that the LS+AR model is more suitable for the short-term forecasts, while the LS+ANN model shows the advantages in the medium- and long-term forecasts. (2) We develop for the first time a new method which combines the autoregressive model and Kalman filter (AR+Kalman) in short-term EOP prediction. The equations of observation and state are established using the EOP series and the autoregressive coefficients

  5. Design and analysis of a high-accuracy flexure hinge.

    PubMed

    Liu, Min; Zhang, Xianmin; Fatikow, Sergej

    2016-05-01

    This paper designs and analyzes a new kind of flexure hinge obtained by using a topology optimization approach, namely, a quasi-V-shaped flexure hinge (QVFH). Flexure hinges are formed by three segments: the left and right segments with convex shapes and the middle segment with straight line. According to the results of topology optimization, the curve equations of profiles of the flexure hinges are developed by numerical fitting. The in-plane dimensionless compliance equations of the flexure hinges are derived based on Castigliano's second theorem. The accuracy of rotation, which is denoted by the compliance of the center of rotation that deviates from the midpoint, is derived. The equations for evaluating the maximum stresses are also provided. These dimensionless equations are verified by finite element analysis and experimentation. The analytical results are within 8% uncertainty compared to the finite element analysis results and within 9% uncertainty compared to the experimental measurement data. Compared with the filleted V-shaped flexure hinge, the QVFH has a higher accuracy of rotation and better ability of preserving the center of rotation position but smaller compliance. PMID:27250469

  6. Realtime and High Accuracy VLBI in Chinese Lunar Exploration Project

    NASA Astrophysics Data System (ADS)

    Weimin, Zheng

    The Chinese VLBI (Very Long Baseline Interferometry) Network - CVN consists of five radio telescopes and one data processing center. CVN is a powerful tracking and navigation tool in the Chinese lunar exploration projects. To meet the quick response of the CE lunar probes navigation requirements, station observation data must be sent to the VLBI center and processed in the real time mode. CVN has demonstrated its ability in the CE -1 and CE-2 missions. In December 2013, the CE-3 lander was successfully sent to the lunar surface and the Yutu rover was released. The new VLBI center and Tianma antenna came into use. During the mission, the lander carried the special Differential Oneway Range (DOR) beacon instead of the normal continuous spectrum VLBI signals. To get the high-precision result, CVN used the delta-DOR technique to track the lander with very extreme accuracy. VLBI delay residuals after orbit determination was nearly 0.5ns. The accuracy of landing position is better than 100 meters. The e-VLBI technique made the observable turnover time as short as 20~40 seconds. The same beam VLBI was used to determine the relative position between the lander and rover with meter accuracy. In the subsequent lunar missions, the new deep stations will join CVN and extend the baseline length. After the soft landing and sampling, the lander will be launched from the lunar surface and finish rendezvous and docking with the orbiter. The VLBI synthesis mapping method and the same beam VLBI can get the accurate lander location and support the rendezvous and docking procedure.

  7. Accuracy Analysis on Large Blocks of High Resolution Images

    NASA Technical Reports Server (NTRS)

    Passini, Richardo M.

    2007-01-01

    Although high altitude frequencies effects are removed at the time of basic image generation, low altitude (Yaw) effects are still present in form of affinity/angular affinity. They are effectively removed by additional parameters. Bundle block adjustment based on properly weighted ephemeris/altitude quaternions (BBABEQ) are not enough to remove the systematic effect. Moreover, due to the narrow FOV of the HRSI, position and altitude are highly correlated making it almost impossible to separate and remove their systematic effects without extending the geometric model (Self-Calib.) The systematic effects gets evident on the increase of accuracy (in terms of RMSE at GCPs) for looser and relaxed ground control at the expense of large and strong block deformation with large residuals at check points. Systematic errors are most freely distributed and their effects propagated all over the block.

  8. Spatial augmented reality based high accuracy human face projection

    NASA Astrophysics Data System (ADS)

    Li, Dong; Xie, Jinghui; Li, Yufeng; Weng, Dongdong; Liu, Yue

    2015-08-01

    This paper discusses the imaging principles and the technical difficulties of spatial augmented reality based human face projection. A novel geometry correction method is proposed to realize fast, high-accuracy face model projection. Using a depth camera to reconstruct the projected object, the relative position from the rendered model to the projector can be accessed and the initial projection image is generated. Then the projected image is distorted by using Bezier interpolation to guarantee that the projected texture matches with the object surface. The proposed method is under a simple process flow and can achieve high perception registration of virtual and real object. In addition, this method has a good performance in the condition that the reconstructed model is not exactly same with the rendered virtual model which extends its application area in the spatial augmented reality based human face projection.

  9. Read-only high accuracy volume holographic optical correlator

    NASA Astrophysics Data System (ADS)

    Zhao, Tian; Li, Jingming; Cao, Liangcai; He, Qingsheng; Jin, Guofan

    2011-10-01

    A read-only volume holographic correlator (VHC) is proposed. After the recording of all of the correlation database pages by angular multiplexing, a stand-alone read-only high accuracy VHC will be separated from the VHC recording facilities which include the high-power laser and the angular multiplexing system. The stand-alone VHC has its own low power readout laser and very compact and simple structure. Since there are two lasers that are employed for recording and readout, respectively, the optical alignment tolerance of the laser illumination on the SLM is very sensitive. The twodimensional angular tolerance is analyzed based on the theoretical model of the volume holographic correlator. The experimental demonstration of the proposed read-only VHC is introduced and discussed.

  10. Accuracy of photon correlation measurements on nonergodic samples.

    PubMed

    Schätzel, K

    1993-07-20

    Three different photon correlation methods are used to obtain the dynamic structure factor of nonergodic samples, such as glasses or gels. These methods are compared in terms of their statistical accuracies and applicabilities. The scheme suggested by Pusey and van Megen [Phys. A 157, 705 (1989)] appears to be the most efficient one, but it is restricted to Gaussian light with a completely frozen nonergodic component. PMID:20830020

  11. 40 CFR 92.127 - Emission measurement accuracy.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... procedure: (i) Span the full analyzer range using a top range calibration gas meeting the calibration gas... applicable requirements of §§ 92.118 through 92.122. (iii) Select a calibration gas (a span gas may be used... increments. This gas must be “named” to an accuracy of ±1.0 percent (±2.0 percent for CO2 span gas) of...

  12. 40 CFR 92.127 - Emission measurement accuracy.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... procedure: (i) Span the full analyzer range using a top range calibration gas meeting the calibration gas... applicable requirements of §§ 92.118 through 92.122. (iii) Select a calibration gas (a span gas may be used... increments. This gas must be “named” to an accuracy of ±1.0 percent (±2.0 percent for CO2 span gas) of...

  13. 40 CFR 92.127 - Emission measurement accuracy.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... procedure: (i) Span the full analyzer range using a top range calibration gas meeting the calibration gas... applicable requirements of §§ 92.118 through 92.122. (iii) Select a calibration gas (a span gas may be used... increments. This gas must be “named” to an accuracy of ±1.0 percent (±2.0 percent for CO2 span gas) of...

  14. 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

  15. High Accuracy 3D Processing of Satellite Imagery

    NASA Technical Reports Server (NTRS)

    Gruen, A.; Zhang, L.; Kocaman, S.

    2007-01-01

    Automatic DSM/DTM generation reproduces not only general features, but also detailed features of the terrain relief. Height accuracy of around 1 pixel in cooperative terrain. RMSE values of 1.3-1.5 m (1.0-2.0 pixels) for IKONOS and RMSE values of 2.9-4.6 m (0.5-1.0 pixels) for SPOT5 HRS. For 3D city modeling, the manual and semi-automatic feature extraction capability of SAT-PP provides a good basis. The tools of SAT-PP allowed the stereo-measurements of points on the roofs in order to generate a 3D city model with CCM The results show that building models with main roof structures can be successfully extracted by HRSI. As expected, with Quickbird more details are visible.

  16. Primary measurement of total ultrasonic power with improved accuracy in rf voltage measurement.

    PubMed

    Dubey, P K; Kumar, Ashok; Kumar, Yudhisther; Gupta, Reeta; Joshi, Deepa

    2010-10-01

    Out of the various existing ultrasonic power measurement techniques, the radiation force balance method using microbalance is most widely used in low power (below 1 W) regime. The major source of uncertainty associated with this technique is the error in ac voltage measurement applied to the transducer for the generation of ultrasonic waves. The sources that deteriorate the ac voltage measurement accuracy include cable length and impedance mismatch. We introduce a new differential peak to peak measurement approach to reduce the ac voltage measurement error. The method holds the average peak amplitude of each polarity. Ultralow offset difference amplifier is used to measure peak to peak voltage. The method is insensitive to the variations in the dc offset of the source. The functionality of this method has been tested and compared with the conventional rf voltage measurement method. The output of this proposed technique is dc, which can be measured with an error of less than 0.1%. PMID:21034111

  17. Measurement accuracy and reliability of tooth length on conventional and CBCT reconstructed panoramic radiographs

    PubMed Central

    Flores-Mir, Carlos; Rosenblatt, Mark R; Major, Paul W.; Carey, Jason P.; Heo, Giseon

    2014-01-01

    INTRODUCTION: This in vivo study assessed accuracy and reliability of tooth length measurements obtained from conventional panoramic radiographs and CBCT panoramic reconstructions to that of a digital caliper (gold standard). METHODS: The sample consisted of subjects who had CBCT and conventional panoramic radiographic imaging and who required maxillary premolar extraction for routine orthodontic treatment. A total of 48 teeth extracted from 26 subjects were measured directly with digital calipers. Radiographic images were scanned and digitally measured in Dolphin 3D software. Accuracy of tooth length measurements made by CBCT panoramic reconstructions, conventional panoramic radiographs and digital caliper (gold standard) were compared to each other by repeated measures one-way ANOVA with Bonferroni correction and by single measures intraclass correlation coefficient. RESULTS: Repeated root length measures with digital calipers, panoramic radiographs and CBCT constructed panoramic-like images were all individually highly reliable. Compared to the caliper (gold standard), tooth measurements obtained from conventional panoramic radiographs were on average 6.3 mm (SD = 2.0 mm) longer, while tooth measurements from CBCT panoramic reconstructions were an average of 1.7 mm (SD = 1.2 mm) shorter. CONCLUSIONS: In comparison to actual tooth lengths, conventional panoramic radiographs were relatively inaccurate, overestimating the lengths by 29%, while CBCT panoramic reconstructions underestimated the lengths by 4%. PMID:25715716

  18. The accuracy of tomographic particle image velocimetry for measurements of a turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Atkinson, Callum; Coudert, Sebastien; Foucaut, Jean-Marc; Stanislas, Michel; Soria, Julio

    2011-04-01

    To investigate the accuracy of tomographic particle image velocimetry (Tomo-PIV) for turbulent boundary layer measurements, a series of synthetic image-based simulations and practical experiments are performed on a high Reynolds number turbulent boundary layer at Reθ = 7,800. Two different approaches to Tomo-PIV are examined using a full-volume slab measurement and a thin-volume "fat" light sheet approach. Tomographic reconstruction is performed using both the standard MART technique and the more efficient MLOS-SMART approach, showing a 10-time increase in processing speed. Random and bias errors are quantified under the influence of the near-wall velocity gradient, reconstruction method, ghost particles, seeding density and volume thickness, using synthetic images. Experimental Tomo-PIV results are compared with hot-wire measurements and errors are examined in terms of the measured mean and fluctuating profiles, probability density functions of the fluctuations, distributions of fluctuating divergence through the volume and velocity power spectra. Velocity gradients have a large effect on errors near the wall and also increase the errors associated with ghost particles, which convect at mean velocities through the volume thickness. Tomo-PIV provides accurate experimental measurements at low wave numbers; however, reconstruction introduces high noise levels that reduces the effective spatial resolution. A thinner volume is shown to provide a higher measurement accuracy at the expense of the measurement domain, albeit still at a lower effective spatial resolution than planar and Stereo-PIV.

  19. Remote sensing and the Mississippi high accuracy reference network

    NASA Technical Reports Server (NTRS)

    Mick, Mark; Alexander, Timothy M.; Woolley, Stan

    1994-01-01

    Since 1986, NASA's Commercial Remote Sensing Program (CRSP) at Stennis Space Center has supported commercial remote sensing partnerships with industry. CRSP's mission is to maximize U.S. market exploitation of remote sensing and related space-based technologies and to develop advanced technical solutions for spatial information requirements. Observation, geolocation, and communications technologies are converging and their integration is critical to realize the economic potential for spatial informational needs. Global positioning system (GPS) technology enables a virtual revolution in geopositionally accurate remote sensing of the earth. A majority of states are creating GPS-based reference networks, or high accuracy reference networks (HARN). A HARN can be defined for a variety of local applications and tied to aerial or satellite observations to provide an important contribution to geographic information systems (GIS). This paper details CRSP's experience in the design and implementation of a HARN in Mississippi and the design and support of future applications of integrated earth observations, geolocation, and communications technology.

  20. An accuracy-response time capacity assessment function that measures performance against standard parallel predictions.

    PubMed

    Townsend, James T; Altieri, Nicholas

    2012-07-01

    Measures of human efficiency under increases in mental workload or attentional limitations are vital in studying human perception, cognition, and action. Assays of efficiency as workload changes have typically been confined to either reaction times (RTs) or accuracy alone. Within the realm of RTs, a nonparametric measure called the workload capacity coefficient has been employed in many studies (Townsend & Nozawa, 1995). However, the contribution of correct versus incorrect responses has been unavailable in that context. A nonparametric statistic that is capable of simultaneously taking into account accuracy as well as RTs would be highly useful. This theoretical study develops such a tool for two important decisional stopping rules. Preliminary data from a simple visual identification study illustrate one potential application. PMID:22775497

  1. Computer-aided high-accuracy testing of reflective surface with reverse Hartmann test.

    PubMed

    Wang, Daodang; Zhang, Sen; Wu, Rengmao; Huang, Chih Yu; Cheng, Hsiang-Nan; Liang, Rongguang

    2016-08-22

    The deflectometry provides a feasible way for surface testing with a high dynamic range, and the calibration is a key issue in the testing. A computer-aided testing method based on reverse Hartmann test, a fringe-illumination deflectometry, is proposed for high-accuracy testing of reflective surfaces. The virtual "null" testing of surface error is achieved based on ray tracing of the modeled test system. Due to the off-axis configuration in the test system, it places ultra-high requirement on the calibration of system geometry. The system modeling error can introduce significant residual systematic error in the testing results, especially in the cases of convex surface and small working distance. A calibration method based on the computer-aided reverse optimization with iterative ray tracing is proposed for the high-accuracy testing of reflective surface. Both the computer simulation and experiments have been carried out to demonstrate the feasibility of the proposed measurement method, and good measurement accuracy has been achieved. The proposed method can achieve the measurement accuracy comparable to the interferometric method, even with the large system geometry calibration error, providing a feasible way to address the uncertainty on the calibration of system geometry. PMID:27557245

  2. Enhancement of strain measurement accuracy using optical extensometer by application of dual-reflector imaging

    NASA Astrophysics Data System (ADS)

    Zhu, Feipeng; Bai, Pengxiang; Shi, Hongjian; Jiang, Zhencheng; Lei, Dong; He, Xiaoyuan

    2016-06-01

    At present, the accuracy of strain measurement using a common optical extensometer with 2D digital image correlation is not sufficient for experimental applications due to the effect of out-of-plane motion. Therefore, this paper proposes a dual-reflector imaging method to improve the accuracy of strain measurement when using a common optical extensometer, with which the front and rear surfaces of a specimen can be simultaneously recorded in the sensor plane of a digital camera. By averaging the strain in two optical extensometers formed on the front and rear surfaces of a specimen, the effect of any slight out-of-plane motion can be eliminated and therefore the strain measurement accuracy can also be improved. Uniaxial tensile tests with an Al-alloy specimen, including static loading and continuous loading, were conducted to validate the feasibility and reliability of the proposed method. The strain measurement results obtained with the proposed method and those obtained with an electrical-resistance strain gauge were found to be in good agreement. The average errors of the proposed method for the two continuous loading tests were found to be 8  ±  10 με and  ‑6  ±  8 με. Given that no correction sheet or compensation specimen is required, the proposed method is easy to implement and thus especially suitable for determining the mechanical properties of brittle materials due to the high level of accuracy with which strain can be measured.

  3. Evaluation of diagnostic accuracy and dimensional measurements by using CBCT in mandibular first molars

    PubMed Central

    Asgary, Saeed; Nikneshan, Sima; Akbarzadeh-Bagheban, Alireza

    2016-01-01

    Background This study aimed to assess the diagnostic accuracy of cone beam computed tomography (CBCT) and quantitatively evaluate the morphology of mandibular first molars using CBCT. Material and Methods Twenty-four double-rooted mandibular first molars were evaluated by NewTom VGi CBCT. The distance from the furcation and apex to the cementoenamel junction (CEJ), diameter and thickness of canal walls, the buccolingual (BL) to mesiodistal (MD) ratio (ΔD), prevalence of oval canals at different sections and taper of the canals were all determined. In order to assess the diagnostic accuracy of CBCT, distance from the furcation and apex to the CEJ and thickness of canal walls at the CEJ and apex were compared with the gold standard values (caliper and stereomicroscope). Statistical analyses were carried out using intraclass correlation coefficient (ICC), paired t-test and repeated measures ANOVA. Results A high correlation existed between the CBCT and gold standard measurements (P<0.001). In dimensional measurements, length of mesial root was higher than the distal root and lingual furcation was farther from the CEJ than the buccal furcation (P<0.001). An important finding of this study was the mesiodistal taper of the mesiobuccal (MB) and mesiolingual (ML) canals; which was equal to 0.02. Conclusions CBCT has acceptable diagnostic accuracy for measurement of canal wall thickness. Cleaning and shaping of the canals should be performed based on the unique anatomy of the respective canal; which necessitates the use of advanced imaging techniques for thorough assessment of root canal anatomy in a clinical setting. Key words:Permanent mandibular first molar, accuracy, cone-beam computed tomography, dimensional measurement. PMID:26855697

  4. Experimental studies of high-accuracy RFID localization with channel impairments

    NASA Astrophysics Data System (ADS)

    Pauls, Eric; Zhang, Yimin D.

    2015-05-01

    Radio frequency identification (RFID) systems present an incredibly cost-effective and easy-to-implement solution to close-range localization. One of the important applications of a passive RFID system is to determine the reader position through multilateration based on the estimated distances between the reader and multiple distributed reference tags obtained from, e.g., the received signal strength indicator (RSSI) readings. In practice, the achievable accuracy of passive RFID reader localization suffers from many factors, such as the distorted RSSI reading due to channel impairments in terms of the susceptibility to reader antenna patterns and multipath propagation. Previous studies have shown that the accuracy of passive RFID localization can be significantly improved by properly modeling and compensating for such channel impairments. The objective of this paper is to report experimental study results that validate the effectiveness of such approaches for high-accuracy RFID localization. We also examine a number of practical issues arising in the underlying problem that limit the accuracy of reader-tag distance measurements and, therefore, the estimated reader localization. These issues include the variations in tag radiation characteristics for similar tags, effects of tag orientations, and reader RSS quantization and measurement errors. As such, this paper reveals valuable insights of the issues and solutions toward achieving high-accuracy passive RFID localization.

  5. Nested uncertainties and hybrid metrology to improve measurement accuracy

    NASA Astrophysics Data System (ADS)

    Silver, R. M.; Zhang, N. F.; Barnes, B. M.; Zhou, H.; Qin, J.; Dixson, R.

    2011-03-01

    In this paper we present a method to combine measurement techniques that reduce uncertainties and improve measurement throughput. The approach has immediate utility when performing model-based optical critical dimension (OCD) measurements. When modeling optical measurements, a library of curves is assembled through the simulation of a multi-dimensional parameter space. Parametric correlation and measurement noise lead to measurement uncertainty in the fitting process resulting in fundamental limitations due to parametric correlations. We provide a strategy to decouple parametric correlation and reduce measurement uncertainties. We also develop the rigorous underlying Bayesian statistical model to apply this methodology to OCD metrology. These statistical methods use a priori information rigorously to reduce measurement uncertainty, improve throughput and develop an improved foundation for comprehensive reference metrology.

  6. Surface Accuracy Measurement Sensor for Deployable Reflector Antennas (SAMS DRA)

    NASA Technical Reports Server (NTRS)

    Neiswander, R. S.

    1980-01-01

    Specifications, system configurations, and concept tests for surface measurement sensors for deployable reflector antennas are presented. Two approaches toward the optical measurement of remote target displacements are discussed: optical ranging, in which the basic measurement is target-to-sensor range; and in particular, optical angular sensing, in which the principle measurements are of target angular displacements lateral to the line of sight. Four representative space antennas are examined.

  7. Measuring Intuition: Nonconscious Emotional Information Boosts Decision Accuracy and Confidence.

    PubMed

    Lufityanto, Galang; Donkin, Chris; Pearson, Joel

    2016-05-01

    The long-held popular notion of intuition has garnered much attention both academically and popularly. Although most people agree that there is such a phenomenon as intuition, involving emotionally charged, rapid, unconscious processes, little compelling evidence supports this notion. Here, we introduce a technique in which subliminal emotional information is presented to subjects while they make fully conscious sensory decisions. Our behavioral and physiological data, along with evidence-accumulator models, show that nonconscious emotional information can boost accuracy and confidence in a concurrent emotion-free decision task, while also speeding up response times. Moreover, these effects were contingent on the specific predictive arrangement of the nonconscious emotional valence and motion direction in the decisional stimulus. A model that simultaneously accumulates evidence from both physiological skin conductance and conscious decisional information provides an accurate description of the data. These findings support the notion that nonconscious emotions can bias concurrent nonemotional behavior-a process of intuition. PMID:27052557

  8. Accuracy of Transcutaneous Carbon Dioxide Measurement in Premature Infants

    PubMed Central

    Janaillac, Marie; Labarinas, Sonia

    2016-01-01

    Background. In premature infants, maintaining blood partial pressure of carbon dioxide (pCO2) value within a narrow range is important to avoid cerebral lesions. The aim of this study was to assess the accuracy of a noninvasive transcutaneous method (TcpCO2), compared to blood partial pressure of carbon dioxide (pCO2). Methods. Retrospective observational study in a tertiary neonatal intensive care unit. We analyzed the correlation between blood pCO2 and transcutaneous values and the accuracy between the trends of blood pCO2 and TcpCO2 in all consecutive premature infants born at <33 weeks' gestational age. Results. 248 infants were included (median gestational age: 29 + 5 weeks and median birth weight: 1250 g), providing 1365 pairs of TcpCO2 and blood pCO2 values. Pearson's R correlation between these values was 0.58. The mean bias was −0.93 kPa with a 95% confidence limit of agreement of −4.05 to +2.16 kPa. Correlation between the trends of TcpCO2 and blood pCO2 values was good in only 39.6%. Conclusions. In premature infants, TcpCO2 was poorly correlated to blood pCO2, with a wide limit of agreement. Furthermore, concordance between trends was equally low. We warn about clinical decision-making on TcpCO2 alone when used as continuous monitoring. PMID:27375901

  9. Improved accuracy of measurements of complex permittivity and permeability using transmission lines

    NASA Astrophysics Data System (ADS)

    Shemelin, V.; Valles, N.

    2014-12-01

    Strong damping of Higher-Order-Modes (HOMs) excited by the beam in accelerating cavities is a necessary condition for achievement of high currents and low emittances in storage rings, electron-positron colliders, and high average power Energy Recovery Linacs (ERLs). Characterization of the electromagnetic properties of lossy ceramics and ferrites used in HOM loads is therefore an essential part of constructing these accelerators. Here we show how to improve these measurements beyond the state of the art. In the past, significant discrepancies have been typical between measured properties for different batches of the same material. Here we show that these can be explained not only by technological deviations in the material production but also by errors in the dimensions of the measured samples. We identify the main source of errors and show how to improve the accuracy of measuring the electromagnetic parameters of absorbing materials.

  10. Accuracy of magnetic resonance imaging for measuring maturing cartilage: A phantom study

    PubMed Central

    McKinney, Jennifer R; Sussman, Marshall S; Moineddin, Rahim; Amirabadi, Afsaneh; Rayner, Tammy; Doria, Andrea S

    2016-01-01

    OBJECTIVES: To evaluate the accuracy of magnetic resonance imaging measurements of cartilage tissue-mimicking phantoms and to determine a combination of magnetic resonance imaging parameters to optimize accuracy while minimizing scan time. METHOD: Edge dimensions from 4 rectangular agar phantoms ranging from 10.5 to 14.5 mm in length and 1.25 to 5.5 mm in width were independently measured by two readers using a steel ruler. Coronal T1 spin echo (T1 SE), fast spoiled gradient-recalled echo (FSPGR) and multiplanar gradient-recalled echo (GRE MPGR) sequences were used to obtain phantom images on a 1.5-T scanner. RESULTS: Inter- and intra-reader reliability were high for both direct measurements and for magnetic resonance imaging measurements of phantoms. Statistically significant differences were noted between the mean direct measurements and the mean magnetic resonance imaging measurements for phantom 1 when using a GRE MPGR sequence (512x512 pixels, 1.5-mm slice thickness, 5:49 min scan time), while borderline differences were noted for T1 SE sequences with the following parameters: 320x320 pixels, 1.5-mm slice thickness, 6:11 min scan time; 320x320 pixels, 4-mm slice thickness, 6:11 min scan time; and 512x512 pixels, 1.5-mm slice thickness, 9:48 min scan time. Borderline differences were also noted when using a FSPGR sequence with 512x512 pixels, a 1.5-mm slice thickness and a 3:36 min scan time. CONCLUSIONS: FSPGR sequences, regardless of the magnetic resonance imaging parameter combination used, provided accurate measurements. The GRE MPGR sequence using 512x512 pixels, a 1.5-mm slice thickness and a 5:49 min scan time and, to a lesser degree, all tested T1 SE sequences produced suboptimal accuracy when measuring the widest phantom. PMID:27464298

  11. Ultrasonic thickness structural health monitoring photoelastic visualization and measurement accuracy for internal pipe corrosion

    NASA Astrophysics Data System (ADS)

    Eason, Thomas J.; Bond, Leonard J.; Lozev, Mark G.

    2015-03-01

    Oil refinery production of fuels is becoming more challenging as a result of the changing world supply of crude oil towards properties of higher density, higher sulfur concentration, and higher acidity. One such production challenge is an increased risk of naphthenic acid corrosion that can result in various surface degradation profiles of uniform corrosion, non-uniform corrosion, and localized pitting in piping systems at temperatures between 150°C and 400°C. The irregular internal surface topology and high external surface temperature leads to a challenging in-service monitoring application for accurate pipe wall thickness measurements. Improved measurement technology is needed to continuously profile the local minimum thickness points of a non-uniformly corroding surface. The measurement accuracy and precision must be sufficient to provide a better understanding of the integrity risk associated with refining crude oils of higher acid concentration. This paper discusses potential technologies for measuring localized internal corrosion in high temperature steel piping and describes the approach under investigation to apply flexible ultrasonic thin-film piezoelectric transducer arrays fabricated by the sol-gel manufacturing process. Next, the elastic wave beam profile of a sol-gel transducer is characterized via photoelastic visualization. Finally, the variables that impact measurement accuracy and precision are discussed and a maximum likelihood statistical method is presented and demonstrated to quantify the measurement accuracy and precision of various time-of-flight thickness calculation methods in an ideal environment. The statistical method results in confidence values analogous to the a90 and a90/95 terminology used in Probability-of-Detection (POD) assessments.

  12. On-orbit Validation and Testing of Thermal Infrared Radiance Accuracy for Spaceborne CO2 Measurements

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Measurements of spectrally resolved thermal infrared (TIR) radiance contain signatures of carbon dioxide that can provide information about its distribution that is complementary to shortwave infrared measurements. In addition, simultaneous retrievals of temperature, water vapor, and other atmospheric constituents can be performed, which provide further insight into scientific questions about the carbon cycle. These measurements of spectral TIR radiance, however, must be made with demonstrable high-accuracy. The University of Wisconsin Space Science and Engineering Center, with support from the NASA Instrument Incubator Program (IIP), has developed the On-orbit Absolute Radiance Standard (OARS), an integrated subsystem that provides on-orbit end-to-end radiometric accuracy validation for infrared remote sensing instruments. The OARS constitutes a high-emissivity (>0.999) blackbody cavity, with an on-board emissivity monitor with uncertainty better than 0.06%, as well as embedded phase change cells that provide on-orbit absolute temperature determination with uncertainties better than 5 mK (k=3). The combined uncertainty of the subsystem is 0.045 K (k=3) in the effective brightness temperature of the blackbody cavity. The OARS was designed to meet the stringent requirements of climate benchmark missions, which require measurement uncertainties better than 0.1 K (k=3) in brightness temperature for the detection of spectral climate signatures. In this paper, we show the sensitivity of TIR radiation to perturbations in atmospheric carbon dioxide concentration, and we present a feasibility study for validating the measurements made by a TIR sensor using the OARS concept in order to make spaceborne measurements of CO2 with demonstrable on-orbit accuracy.

  13. Testing Accuracy of Long-Range Ultrasonic Sensors for Olive Tree Canopy Measurements

    PubMed Central

    Gamarra-Diezma, Juan Luis; Miranda-Fuentes, Antonio; Llorens, Jordi; Cuenca, Andrés; Blanco-Roldán, Gregorio L.; Rodríguez-Lizana, Antonio

    2015-01-01

    Ultrasonic sensors are often used to adjust spray volume by allowing the calculation of the crown volume of tree crops. The special conditions of the olive tree require the use of long-range sensors, which are less accurate and faster than the most commonly used sensors. The main objectives of the study were to determine the suitability of the sensor in terms of sound cone determination, angle errors, crosstalk errors and field measurements. Different laboratory tests were performed to check the suitability of a commercial long-range ultrasonic sensor, as were the experimental determination of the sound cone diameter at several distances for several target materials, the determination of the influence of the angle of incidence of the sound wave on the target and distance on the accuracy of measurements for several materials and the determination of the importance of the errors due to interference between sensors for different sensor spacings and distances for two different materials. Furthermore, sensor accuracy was tested under real field conditions. The results show that the studied sensor is appropriate for olive trees because the sound cone is narrower for an olive tree than for the other studied materials, the olive tree canopy does not have a large influence on the sensor accuracy with respect to distance and angle, the interference errors are insignificant for high sensor spacings and the sensor's field distance measurements were deemed sufficiently accurate. PMID:25635414

  14. Testing accuracy of long-range ultrasonic sensors for olive tree canopy measurements.

    PubMed

    Gamarra-Diezma, Juan Luis; Miranda-Fuentes, Antonio; Llorens, Jordi; Cuenca, Andrés; Blanco-Roldán, Gregorio L; Rodríguez-Lizana, Antonio

    2015-01-01

    Ultrasonic sensors are often used to adjust spray volume by allowing the calculation of the crown volume of tree crops. The special conditions of the olive tree require the use of long-range sensors, which are less accurate and faster than the most commonly used sensors. The main objectives of the study were to determine the suitability of the sensor in terms of sound cone determination, angle errors, crosstalk errors and field measurements. Different laboratory tests were performed to check the suitability of a commercial long-range ultrasonic sensor, as were the experimental determination of the sound cone diameter at several distances for several target materials, the determination of the influence of the angle of incidence of the sound wave on the target and distance on the accuracy of measurements for several materials and the determination of the importance of the errors due to interference between sensors for different sensor spacings and distances for two different materials. Furthermore, sensor accuracy was tested under real field conditions. The results show that the studied sensor is appropriate for olive trees because the sound cone is narrower for an olive tree than for the other studied materials, the olive tree canopy does not have a large influence on the sensor accuracy with respect to distance and angle, the interference errors are insignificant for high sensor spacings and the sensor's field distance measurements were deemed sufficiently accurate. PMID:25635414

  15. A novel low coherence fibre optic interferometer for position and thickness measurements with unattained accuracy

    NASA Astrophysics Data System (ADS)

    Wilhelm, Rainer; Courteville, Alain; Garcia, Fabrice

    2006-04-01

    This paper presents the second generation LISE-LI of the fibre-optics Low coherence Interferometric Sensor (LISE), recently developed by FOGALE nanotech. Based on the proven concept of partial coherence interferometry, the LISE system works as a comparator of optical group delays. The group delay along the optical axis in the probe interferometer arm containing the object to be measured is compared with the group delay along the optical axis of the reference interferometer arm containing a delay line. The latter consists of a mirror that can be linearly displaced on a translation stage. The light source is a super luminescent diode emitting at near infrared wavelength (typically 1.31 μm) with a spectral bandwidth of a few tens of nm. Thanks to the limited temporal coherence of the source, multiple surfaces of the object can be detected during a single scan of the delay line. Measurement ranges are between a few mm up to 600 mm (optical thickness). The measurement zone can be placed at a working distance of up to several meters away from the instrument's exit. Applications in industry and in research laboratories include thickness measurements of individual optical elements (e.g. lenses), technical multi-layer glasses, glue and varnish layers deposited on various substrates, Si or GaAs wafers, and position measurements of multiple elements of an optical system (e.g. a photographic lens). Compared to the first generation of the system, the absolute accuracy of the second generation system is about ten times better, reaching a level of +/-100 nm for thickness measurements over the full measurement range. Following an introductory description of the measurement principle, the first part of the paper focuses on the key elements in the system design, both in hardware and detection algorithm, that ensure the high accuracy level. The second part of the paper presents an experimental validation of the achieved accuracy level. We present results of thickness measurements on

  16. Evapotranspiration information reporting: I. Factors governing measurement accuracy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    More and more evapotranspiration (ET) models, ET crop coefficients, and associated measurements of ET are being reported in the literature and used to develop, calibrate, and test important ET process models. Evapotranspiration data are derived from a range of measurement systems including lysimeter...

  17. Accuracy of Estimations of Measurements by Students with Visual Impairments

    ERIC Educational Resources Information Center

    Jones, M. Gail; Forrester, Jennifer H.; Robertson, Laura E.; Gardner, Grant E.; Taylor, Amy R.

    2012-01-01

    There is a dearth of information about how students with visual impairments learn science-process skills. This study investigated students' concepts and skills in one science area: the estimation of measurements. The estimation of measurements is one of the fundamental concepts that connects all science disciplines that provide the necessary…

  18. Nerve conduction velocity measurements: improved accuracy using superimposed response waves.

    PubMed

    Halar, E M; Venkatesh, B

    1976-10-01

    A new procedure of serial motor nerve conduction velocity (NCV) measurements with the use of "superimposed response waves" technique (or double stimulus technique) was performed on 29 normal subjects. Six peripheral nerves were tested once a week for four to six weeks. A total of 760 NCV measurements were thus obtained to try to assess the magnitude of error in serial NCV testings. With the double stimulus technique employed, a significant reduction in variations of serial NCV measurements was found. The overall standard deviation of four to six consecutive NCV measurements in the 34 subjects was 1.3 meters per second with a coefficient of variation of 2.4%. These findings obtained with the double stimulus technique have proven to be approximately three times more accurate than results obtained by investigators who studied nerve conduction velocity measurement variation with single stimulus standard NCV testing techniques. PMID:184754

  19. 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.

  20. Accuracy and precision of four common peripheral temperature measurement methods in intensive care patients

    PubMed Central

    Asadian, Simin; Khatony, Alireza; Moradi, Gholamreza; Abdi, Alireza; Rezaei, Mansour

    2016-01-01

    Introduction An accurate determination of body temperature in critically ill patients is a fundamental requirement for initiating the proper process of diagnosis, and also therapeutic actions; therefore, the aim of the study was to assess the accuracy and precision of four noninvasive peripheral methods of temperature measurement compared to the central nasopharyngeal measurement. Methods In this observational prospective study, 237 patients were recruited from the intensive care unit of Imam Ali Hospital of Kermanshah. The patients’ body temperatures were measured by four peripheral methods; oral, axillary, tympanic, and forehead along with a standard central nasopharyngeal measurement. After data collection, the results were analyzed by paired t-test, kappa coefficient, receiver operating characteristic curve, and using Statistical Package for the Social Sciences, version 19, software. Results There was a significant meaningful correlation between all the peripheral methods when compared with the central measurement (P<0.001). Kappa coefficients showed good agreement between the temperatures of right and left tympanic membranes and the standard central nasopharyngeal measurement (88%). Paired t-test demonstrated an acceptable precision with forehead (P=0.132), left (P=0.18) and right (P=0.318) tympanic membranes, oral (P=1.00), and axillary (P=1.00) methods. Sensitivity and specificity of both the left and right tympanic membranes were more than for other methods. Conclusion The tympanic and forehead methods had the highest and lowest accuracy for measuring body temperature, respectively. It is recommended to use the tympanic method (right and left) for assessing a patient’s body temperature in the intensive care units because of high accuracy and acceptable precision. PMID:27621673

  1. Improvement of measuring accuracy of an optical CMM

    NASA Astrophysics Data System (ADS)

    Chao, Z. X.; Ong, S. S.; Tan, S. L.

    In this paper, a laser interferometer was used to evaluate the linear performance of an optical coordinate measuring machine with a measuring area of 400 mm x 400 mm at 20-mm interval. The evaluation results show that the linear performance of the Y-axis varies a lot at different X positions and offline error compensation method was implemented. A 200 mm glass scale was used to verify the method. The results showed that the variations at different X positions improved from 0.35 μm to 0.15 μm within the compensated area. A better measurement uncertainty was also achieved.

  2. Impact of soil texture on soil moisture measurement accuracy by TDR in Sistan plain of Iran

    NASA Astrophysics Data System (ADS)

    sarani, noushin; Afrasiab, Peyman

    2014-05-01

    In the recent past, many researchers have developed various techniques for determining moisture content of soil. Among the various methods of estimating soil moisture, Time Domain Reflectometry (TDR) method is a relatively new method. TDR has been widely used in water system investigation in Agriculture, Geosciences, etc. The purpose of this study is determination of moisture measurement accuracy by TDR in various soil textures in Sistan plain. For this purpose, six textures and for each of them three Iteration were used. The studied textures were clay, loam, sandy loam, sandy clay loam, clay loam and sandy. The experiments were carried out at the laboratory of water engineering department of Zabol University in Iran. The provided textures were laid in the PVC cylinder with 50 cm height and 30 cm diameter. After 24 h of saturation, the soil water content of the samples was measured by oven-dry gravimetric and TDR methods. In each day the moisture measurement of each texture was carried out by these two methods until a moisture range was determined. For comparison between measured moisture values by TDR and gravimetric method, two statistical parameters include coefficient of determination (R2) and root mean square error (RMSE) were applied here. The results showed that by using SPSS, statistically significant at probably level of 1% indicated no difference between the measured value of moisture by TDR device and gravimetric method. For heavy textures consist of sandy clay loam, clay loam, and clay with increasing clay content when the moisture was low, TDR measured the moisture values less than the gravimetric method. Furthermore for light textures consist of sandy loam and sand, the TDR device measured the moisture values more than the gravimetric method. Also for clay loam and sandy clay at high moisture values, data measured by TDR was close to the gravimetric method. For all studied textures with increasing of clay content, the fitted lines slope and RMSE

  3. Development of a high-speed nanoprofiler using normal vector tracing method for high-accuracy mirrors

    NASA Astrophysics Data System (ADS)

    Okuda, Kohei; Kitayama, Takao; Usuki, Koji; Kojima, Takuya; Okita, Kenya; Uchikoshi, Junichi; Higashi, Yasuo; Endo, Katsuyoshi

    2013-09-01

    High-precision optical elements are used in various fields. Ultraprecise aspherical mirrors that offer nanofocusing and high coherence are used to concentrate high-brightness X-rays in developing third-generation synchrotron radiation facilities. In industry, extreme ultraviolet (wavelength: 13.5 nm) lithography, which is used to fabricate semiconductor devices, uses high-accuracy aspherical mirrors for its projection optical systems. The demand for rapid progress in nanomeasurement technologies is increasing because it is difficult to realize next-generation ultraprecise mirrors with the required precision by conventional processing. The measuring method itself requires superhigh precision. We developed an innovative nanoprofiler that can directly measure the figure of high-accuracy mirrors without using a reference surface. The principle of our measuring method is to determine the normal vectors by causing the optical paths of the incident and reflected light at the measurement point to coincide; it is based on the straightness of laser light and the accuracy of rotational goniometers. From the acquired normal vectors and their coordinates, the three-dimensional shape is calculated by a reconstruction algorithm. We measured concave spherical mirrors and compared the results with those using a Fizeau interferometer. The profiles of the mirrors were consistent within the range of error in their middle portions. In addition, we evaluated the performance of an airflow control unit by measuring a concave spherical mirror. This unit suppressed the influence of environmental change, and drastically improved the repeatability.

  4. 40 CFR 86.1338-2007 - Emission measurement accuracy.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test... measured by the oxides of nitrogen analyzer following the analyzer's monthly periodic calibration....

  5. 40 CFR 86.1338-2007 - Emission measurement accuracy.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test... measured by the oxides of nitrogen analyzer following the analyzer's monthly periodic calibration....

  6. 40 CFR 86.1338-2007 - Emission measurement accuracy.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test... measured by the oxides of nitrogen analyzer following the analyzer's monthly periodic calibration....

  7. 40 CFR 86.1338-2007 - Emission measurement accuracy.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test... measured by the oxides of nitrogen analyzer following the analyzer's monthly periodic calibration....

  8. Measuring Speech Recognition Proficiency: A Psychometric Analysis of Speed and Accuracy

    ERIC Educational Resources Information Center

    Rader, Martha H.; Bailey, Glenn A.; Kurth, Linda A.

    2008-01-01

    This study examined the validity of various measures of speed and accuracy for assessing proficiency in speech recognition. The study specifically compared two different word-count indices for speed and accuracy (the 5-stroke word and the 1.4-syllable standard word) on a timing administered to 114 speech recognition students measured at 1-, 2-,…

  9. High-accuracy simulation-based optical proximity correction

    NASA Astrophysics Data System (ADS)

    Keck, Martin C.; Henkel, Thomas; Ziebold, Ralf; Crell, Christian; Thiele, J.÷rg

    2003-12-01

    In times of continuing aggressive shrinking of chip layouts a thorough understanding of the pattern transfer process from layout to silicon is indispensable. We analyzed the most prominent effects limiting the control of this process for a contact layer like process, printing 140nm features of variable length and different proximity using 248nm lithography. Deviations of the photo mask from the ideal layout, in particular mask off-target and corner rounding have been identified as clearly contributing to the printing behavior. In the next step, these deviations from ideal behavior have been incorporated into the optical proximity correction (OPC) modeling process. The degree of accuracy for describing experimental data by simulation, using an OPC model modified in that manner could be increased significantly. Further improvement in modeling the optical imaging process could be accomplished by taking into account lens aberrations of the exposure tool. This suggests a high potential to improve OPC by considering the effects mentioned, delivering a significant contribution to extending the application of OPC techniques beyond current limits.

  10. Accuracy Advances in Measuring Earth Emission Spectra for Weather and Climate

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Launch of the first component of the Joint Polar Satellite System (JPSS) in late October is expected to initiate a new series of US afternoon satellites to complement the EUMETSAT MetOp EPS morning observations. A key component is the Cross-track Infrared Sounder (CrIS) designed for advanced temperature and water vapor profiling for weather and climate applications. We have worked on getting this operational capability in space ever since conducting a Phase A instrument design in 1990, and will report on what is expected to be its highly accurate radiometric and spectral performance post launch. The expectation from thermal/vacuum testing is that the accuracy will exceed 0.2 K (k=3) brightness temperature at scene temperature for all three bands in the region from 3.5 to 15 microns. CrIS is expected to offer further confirmation of techniques that have proven to offer significant accuracy improvements for the new family of advanced sounding instruments including AIRS on NASA Aqua platform and IASI on MetOp A and that are needed in the new IR Decadal Survey measurements. CrIS and these other advanced sounders help set the stage for a new era in establishing spectrally resolved IR climate benchmark measurements from space. Here we report on being able to achieve even higher accuracy with instruments designed specifically for climate missions similar to the Decadal Survey Climate Absolute Radiance and Refractivity Observatory (CLARREO). Results will be presented from our NASA Instrument Incubator Program (IIP) effort for which a new concept for on-orbit verification and test has been developed. This system is capable of performing fundamental radiometric calibration, spectral characterization and calibration, and other key performance tests that are normally only performed prior to launch in thermal/vacuum testing. By verifying accuracy directly on-orbit, this capability should provide the ultra-high confidence in data sets needed for societal decision making.

  11. Ultracompact vibrometry measurement with nanometric accuracy using optical feedback

    NASA Astrophysics Data System (ADS)

    Jha, Ajit; Azcona, Francisco; Royo, Santiago

    2015-05-01

    The nonlinear dynamics of a semiconductor laser with optical feedback (OF) combined with direct current modulation of the laser is demonstrated to suffice for the measurement of subwavelength changes in the position of a vibrating object. So far, classical Optical Feedback Interferometry (OFI) has been used to measure the vibration of an object given its amplitude is greater than half the wavelength of emission, and the resolution of the measurement limited to some tenths of the wavelength after processing. We present here a methodology which takes advantage of the combination of two different phenomena: continuous wave frequency modulation (CWFM), induced by direct modulation of the laser, and non-linear dynamics inside of the laser cavity subject to optical self-injection (OSI). The methodology we propose shows how to detect vibration amplitudes smaller than half the emission wavelength with resolutions way beyond λ/2, extending the typical performance of OFI setups to very small amplitudes. A detailed mathematical model and simulation results are presented to support the proposed methodology, showing its ability to perform such displacement measurements of frequencies in the MHz range, depending upon the modulation frequency. Such approach makes the technique a suitable candidate, among other applications, to economic laser-based ultrasound measurements, with applications in nondestructive testing of materials (thickness, flaws, density, stresses), among others. The results of simulations of the proposed approach confirm the merit of the figures as detection of amplitudes of vibration below λ/2) with resolutions in the nanometer range.

  12. The effect of clock, media, and station location errors on Doppler measurement accuracy

    NASA Technical Reports Server (NTRS)

    Miller, J. K.

    1993-01-01

    Doppler tracking by the Deep Space Network (DSN) is the primary radio metric data type used by navigation to determine the orbit of a spacecraft. The accuracy normally attributed to orbits determined exclusively with Doppler data is about 0.5 microradians in geocentric angle. Recently, the Doppler measurement system has evolved to a high degree of precision primarily because of tracking at X-band frequencies (7.2 to 8.5 GHz). However, the orbit determination system has not been able to fully utilize this improved measurement accuracy because of calibration errors associated with transmission media, the location of tracking stations on the Earth's surface, the orientation of the Earth as an observing platform, and timekeeping. With the introduction of Global Positioning System (GPS) data, it may be possible to remove a significant error associated with the troposphere. In this article, the effect of various calibration errors associated with transmission media, Earth platform parameters, and clocks are examined. With the introduction of GPS calibrations, it is predicted that a Doppler tracking accuracy of 0.05 microradians is achievable.

  13. The ultimate quantum limits on the accuracy of measurements

    NASA Technical Reports Server (NTRS)

    Yuen, Horace P.

    1992-01-01

    A quantum generalization of rate-distortion theory from standard communication and information theory is developed for application to determining the ultimate performance limit of measurement systems in physics. For the estimation of a real or a phase parameter, it is shown that the root-mean-square error obtained in a measurement with a single-mode photon level N cannot do better than approximately N exp -1, while approximately exp(-N) may be obtained for multi-mode fields with the same photon level N. Possible ways to achieve the remarkable exponential performance are indicated.

  14. High mass accuracy and high mass resolving power FT-ICR secondary ion mass spectrometry for biological tissue imaging.

    PubMed

    Smith, Donald F; Kiss, Andras; Leach, Franklin E; Robinson, Errol W; Paša-Tolić, Ljiljana; Heeren, Ron M A

    2013-07-01

    Biological tissue imaging by secondary ion mass spectrometry has seen rapid development with the commercial availability of polyatomic primary ion sources. Endogenous lipids and other small bio-molecules can now be routinely mapped on the sub-micrometer scale. Such experiments are typically performed on time-of-flight mass spectrometers for high sensitivity and high repetition rate imaging. However, such mass analyzers lack the mass resolving power to ensure separation of isobaric ions and the mass accuracy for elemental formula assignment based on exact mass measurement. We have recently reported a secondary ion mass spectrometer with the combination of a C60 primary ion gun with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) for high mass resolving power, high mass measurement accuracy, and tandem mass spectrometry capabilities. In this work, high specificity and high sensitivity secondary ion FT-ICR MS was applied to chemical imaging of biological tissue. An entire rat brain tissue was measured with 150 μm spatial resolution (75 μm primary ion spot size) with mass resolving power (m/Δm(50%)) of 67,500 (at m/z 750) and root-mean-square measurement accuracy less than two parts-per-million for intact phospholipids, small molecules and fragments. For the first time, ultra-high mass resolving power SIMS has been demonstrated, with m/Δm(50%) > 3,000,000. Higher spatial resolution capabilities of the platform were tested at a spatial resolution of 20 μm. The results represent order of magnitude improvements in mass resolving power and mass measurement accuracy for SIMS imaging and the promise of the platform for ultra-high mass resolving power and high spatial resolution imaging. PMID:23685962

  15. Silver Coating for High-Mass-Accuracy Imaging Mass Spectrometry of Fingerprints on Nanostructured Silicon.

    PubMed

    Guinan, Taryn M; Gustafsson, Ove J R; McPhee, Gordon; Kobus, Hilton; Voelcker, Nicolas H

    2015-11-17

    Nanostructure imaging mass spectrometry (NIMS) using porous silicon (pSi) is a key technique for molecular imaging of exogenous and endogenous low molecular weight compounds from fingerprints. However, high-mass-accuracy NIMS can be difficult to achieve as time-of-flight (ToF) mass analyzers, which dominate the field, cannot sufficiently compensate for shifts in measured m/z values. Here, we show internal recalibration using a thin layer of silver (Ag) sputter-coated onto functionalized pSi substrates. NIMS peaks for several previously reported fingerprint components were selected and mass accuracy was compared to theoretical values. Mass accuracy was improved by more than an order of magnitude in several cases. This straightforward method should form part of the standard guidelines for NIMS studies for spatial characterization of small molecules. PMID:26460234

  16. 40 CFR 86.338-79 - Exhaust measurement accuracy.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... percent of full-scale chart deflection during the measurement of the emissions for each mode. The... percent of full-scale if the full-scale value is 155 ppm (or ppm C) or less. (2) Option. For CO analysis the analyzer's response may be less than 15 percent of full scale if the full-scale value is 5500...

  17. Measuring the Accuracy of Prediction in a Simulated Environment.

    ERIC Educational Resources Information Center

    Mailles, Stephanie; Batatia, Hadj

    1998-01-01

    Describes use of a computerized simulation to study prediction in a complex environment (i.e., bus traffic control). Nature of the task, presentation method, number of repetitions, and length of time taken for prediction were measured. Prediction was significantly affected by all factors except number of repetitions. No learning effect was…

  18. 30 CFR 74.8 - Measurement, accuracy, and reliability requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51... COAL MINE SAFETY AND HEALTH COAL MINE DUST SAMPLING DEVICES Requirements for Continuous Personal Dust... requirement. The CPDM shall be capable of measuring respirable dust within the personal breathing zone of...

  19. 30 CFR 74.8 - Measurement, accuracy, and reliability requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51... COAL MINE SAFETY AND HEALTH COAL MINE DUST SAMPLING DEVICES Requirements for Continuous Personal Dust... requirement. The CPDM shall be capable of measuring respirable dust within the personal breathing zone of...

  20. 30 CFR 74.8 - Measurement, accuracy, and reliability requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51... COAL MINE SAFETY AND HEALTH COAL MINE DUST SAMPLING DEVICES Requirements for Continuous Personal Dust... requirement. The CPDM shall be capable of measuring respirable dust within the personal breathing zone of...

  1. Evaluation of the Aurora Application Shade Measurement Accuracy

    SciTech Connect

    2015-12-01

    Aurora is an integrated, Web-based application that helps solar installers perform sales, engineering design, and financial analysis. One of Aurora's key features is its high-resolution remote shading analysis.

  2. Improving optical measurement accuracy using multi-technique nested uncertainties

    NASA Astrophysics Data System (ADS)

    Silver, R. M.; Zhang, N. F.; Barnes, B. M.; Zhou, H.; Heckert, A.; Dixson, R.; Germer, T. A.; Bunday, B.

    2009-03-01

    This paper compares and contrasts different combinations of scatterfield and scatterometry optical configurations as well as introduces a new approach to embedding atomic force microscopy (AFM) or other reference metrology results directly in the uncertainty analysis and library-fitting process to reduce parametric uncertainties. We present both simulation results and experimental data demonstrating this new method, which is based on the application of a Bayesian analysis to library-based regression fitting of optical critical dimension (OCD) data. We develop the statistical methods to implement this approach of nested uncertainty analysis and give several examples, which demonstrate reduced uncertainties in the final combined measurements. The approach is also demonstrated through a combined reference metrology application using several independent measurement methods.

  3. On the accuracy of PLIF measurements in slender plumes

    NASA Astrophysics Data System (ADS)

    Vanderwel, Christina; Tavoularis, Stavros

    2014-08-01

    The purpose of this article was to assess the measurement uncertainty of the planar laser-induced fluorescence (PLIF) method and, as much as possible, to devise corrections for predictable biases. More specifically, we considered the measurement of concentration maps in cross sections parallel to and normal to the axis of a slender plume containing Rhodamine 6G as a passive scalar tracer and transported by a turbulent shear flow. In addition to previously examined sources of error related to PLIF, we also investigated several unexplored ones. First, we demonstrated that errors would arise if the laser sheet thickness was comparable to or larger than the thickness of the instantaneous plume. We then investigated the effect of secondary fluorescence, which was attributed to absorption and re-emission of primary fluorescence by dye both within and outside the laser sheet. We found that, if uncorrected, this effect would contaminate the calibration as well as the instantaneous concentration measurements of the plume, and proposed methods for the correction of these errors and for identifying the instantaneous boundaries of the in-sheet dye regions.

  4. Theoretical Accuracy of Along-Track Displacement Measurements from Multiple-Aperture Interferometry (MAI)

    PubMed Central

    Jung, Hyung-Sup; Lee, Won-Jin; Zhang, Lei

    2014-01-01

    The measurement of precise along-track displacements has been made with the multiple-aperture interferometry (MAI). The empirical accuracies of the MAI measurements are about 6.3 and 3.57 cm for ERS and ALOS data, respectively. However, the estimated empirical accuracies cannot be generalized to any interferometric pair because they largely depend on the processing parameters and coherence of the used SAR data. A theoretical formula is given to calculate an expected MAI measurement accuracy according to the system and processing parameters and interferometric coherence. In this paper, we have investigated the expected MAI measurement accuracy on the basis of the theoretical formula for the existing X-, C- and L-band satellite SAR systems. The similarity between the expected and empirical MAI measurement accuracies has been tested as well. The expected accuracies of about 2–3 cm and 3–4 cm (γ = 0.8) are calculated for the X- and L-band SAR systems, respectively. For the C-band systems, the expected accuracy of Radarsat-2 ultra-fine is about 3–4 cm and that of Sentinel-1 IW is about 27 cm (γ = 0.8). The results indicate that the expected MAI measurement accuracy of a given interferometric pair can be easily calculated by using the theoretical formula. PMID:25251408

  5. Theoretical accuracy of along-track displacement measurements from multiple-aperture interferometry (MAI).

    PubMed

    Jung, Hyung-Sup; Lee, Won-Jin; Zhang, Lei

    2014-01-01

    The measurement of precise along-track displacements has been made with the multiple-aperture interferometry (MAI). The empirical accuracies of the MAI measurements are about 6.3 and 3.57 cm for ERS and ALOS data, respectively. However, the estimated empirical accuracies cannot be generalized to any interferometric pair because they largely depend on the processing parameters and coherence of the used SAR data. A theoretical formula is given to calculate an expected MAI measurement accuracy according to the system and processing parameters and interferometric coherence. In this paper, we have investigated the expected MAI measurement accuracy on the basis of the theoretical formula for the existing X-, C- and L-band satellite SAR systems. The similarity between the expected and empirical MAI measurement accuracies has been tested as well. The expected accuracies of about 2-3 cm and 3-4 cm (γ = 0.8) are calculated for the X- and L-band SAR systems, respectively. For the C-band systems, the expected accuracy of Radarsat-2 ultra-fine is about 3-4 cm and that of Sentinel-1 IW is about 27 cm (γ = 0.8). The results indicate that the expected MAI measurement accuracy of a given interferometric pair can be easily calculated by using the theoretical formula. PMID:25251408

  6. High-Accuracy Potentials for Van Der Waals Systems

    NASA Astrophysics Data System (ADS)

    Dawes, Richard; Wang, Xiao-Gang; Brown, James; Carrington, Tucker; , Jr.

    2012-06-01

    Recent experimental studies of vdWs systems including those by Moazzen-Ahmadi and McKellar,1,2 as well as microwave studies by Minei and Novick3,4 have observed previously unknown stable polar isomers for systems such as (NNO)2 and (OCS)2. The multi-welled floppy nature of the PESs and the small barriers between minima place stringent requirements on the PES for a successful theoretical description of these states. An automated method of generating accurate PESs for vdW systems has been developed and is demonstrated here.5,6 A limited number of ab initio data at the explicitly correlated CCSD(T)-F12b level are interpolated into analytic PESs with negligible fitting error. High-accuracy PESs were developed for a number of systems including (NNO)2, (OCS)2, (CO)2, CO2:CS2 and (NH3)2. Using the PESs, the rovibrational Schrödinger equation is solved with a symmetry-adapted Lanczos algorithm and an uncoupled product basis set. All inter-monomer coordinates are included in the calculations. Calculated transition frequencies are in very close agreement with experiment. References (1) M. Dehghani, M. Afshari, Z. Abusara, N. Moazzen-Ahmadi, A. R. W. McKellar, J. Chem. Phys. 126, 164310 (2007). (2) M. Dehghani, M. Afshari, Z. Abusara, N. Moazzen-Ahmadi, A. R. W. McKellar, J. Chem. Phys. 126, 071102 (2007). (3) N. R. Walker, R. Nicholas, A. J. Minei, S. E. Novick, A. C. Legon, J. Mol. Spec. 251, 153 (2008). (4) A. J. Minei and S. E. Novick, J. Chem. Phys. 126, 101101 (2007). (5) R. Dawes, X.-G. Wang, A. W. Jasper, T. Carrington Jr., J. Chem. Phys. 133, 134304 (2010). (6) X.-G. Wang, T. Carrington Jr., R. Dawes and A. W. Jasper, J. Mol. Spec. 268, 53 (2011).

  7. Strategy to attain high spatial accuracy in Forest Cover Classification

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Vijayan, D.; Prasad, T. S.

    Forest cover and its type have primary role in the processes associated with land and global change Not only the area statistics for the different type of forest covers but also the correctness of their spatial distribution matching of classified output with GIS overlay are important for process studies As maximum likelihood ML is widely practiced classification algorithm for extracting thematic information from satellite images critical evaluation was undertaken using IRS LISS-III image of Antilova tropical moist deciduous forest bounded by 17 r 50 to 17 r 56 N in latitude and 81 r 45 to 81 r 54 E in longitude for which 100 ground information in the from of GIS overlay was available GIS overlay has 9 thematic classes i e 27 13 dense DF 25 60 Semi-evergreen SE 29 38 mixed MF 0 25 bamboo BA 5 70 teak TK forests 5 88 grassland GL 4 83 podu blank PO 1 21 Settlements SET and water 0 026 WA ML classifier in general starts with equal a priori probability for all the classes method a Availability of information on cover under each thematic class enables assigning of a priori probability to each thematic class method b Method b always gave better results as compared to method a With the goal to improve classification accuracy CA the GL and MF classes that had high standard deviation of 10 29 and 11 29 in NIR band were divided into subclasses Inclusion of sub-classes in GR improved the area statistics and spatial

  8. High Mass Accuracy and High Mass Resolving Power FT-ICR Secondary Ion Mass Spectrometry for Biological Tissue Imaging

    SciTech Connect

    Smith, Donald F.; Kiss, Andras; Leach, Franklin E.; Robinson, Errol W.; Pasa-Tolic, Ljiljana; Heeren, Ronald M.

    2013-07-01

    Biological tissue imaging by secondary ion mass spectrometry has seen rapid development with the commercial availability of polyatomic primary ion sources. Endogenous lipids and other small bio-molecules can now be routinely mapped on the micrometer scale. Such experiments are typically performed on time-of-flight mass spectrometers for high sensitivity and high repetition rate imaging. However, such mass analyzers lack the mass resolving power to ensure separation of isobaric ions and the mass accuracy for exact mass elemental formula assignment. We have recently reported a secondary ion mass spectrometer with the combination of a C60 primary ion gun with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) for high mass resolving power, high mass measurement accuracy and tandem mass spectrometry capabilities. In this work, high specificity and high sensitivity secondary ion FT-ICR MS was applied to chemical imaging of biological tissue. An entire rat brain tissue was measured with 150 μm spatial resolution (75 μm primary ion spot size) with mass resolving power (m/Δm50%) of 67,500 (at m/z 750) and root-mean-square measurement accuracy less than two parts-per-million for intact phospholipids, small molecules and fragments. For the first time, ultra-high mass resolving power SIMS has been demonstrated, with m/Δm50% > 3,000,000. Higher spatial resolution capabilities of the platform were tested at a spatial resolution of 20 μm. The results represent order of magnitude improvements in mass resolving power and mass measurement accuracy for SIMS imaging and the promise of the platform for ultra-high mass resolving power and high spatial resolution imaging.

  9. Accuracy of endodontic microleakage results: autoradiographic vs. volumetric measurements.

    PubMed

    Ximénez-Fyvie, L A; Ximénez-García, C; Carter-Bartlett, P M; Collado-Webber, F J

    1996-06-01

    The correlation between autoradiographic and volumetric leakage measurements was evaluated. Seventy-two anterior teeth with a single canal were selected and divided into three groups of 24. Group 1 served as control (no obturation), group 2 was obturated with gutta-percha only, and group 3 was obturated with gutta-percha and endodontic sealer. Samples were placed in a vertical position in 48-well cell culture plates and immersed in 1 ml of [14C]urea for 14 days. One-mm-thick horizontal serial sections were cut with a diamond disk cooled with liquid-nitrogen gas. Linear penetration was recorded by five independent evaluators from autoradiographs. Volumetric results were based on counts per minute registered in a liquid scintillation spectrometer. Pearson's correlation coefficient test was used to determine the lineal correlation between both methods of evaluation. No acceptable correlation values were found in any of the three groups (group 1, r = 0.34; group 2, r = 0.23; group 3, r = 0.20). Our results indicate that there is no correlation between linear and volumetric measurements of leakage. PMID:8934988

  10. High accuracy laboratory spectroscopy to support active greenhouse gas sensing

    NASA Astrophysics Data System (ADS)

    Long, D. A.; Bielska, K.; Cygan, A.; Havey, D. K.; Okumura, M.; Miller, C. E.; Lisak, D.; Hodges, J. T.

    2011-12-01

    Recent carbon dioxide (CO2) remote sensing missions have set precision targets as demanding as 0.25% (1 ppm) in order to elucidate carbon sources and sinks [1]. These ambitious measurement targets will require the most precise body of spectroscopic reference data ever assembled. Active sensing missions will be especially susceptible to subtle line shape effects as the narrow bandwidth of these measurements will greatly limit the number of spectral transitions which are employed in retrievals. In order to assist these remote sensing missions we have employed frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) [2], a high-resolution, ultrasensitive laboratory technique, to measure precise line shape parameters for transitions of O2, CO2, and other atmospherically-relevant species within the near-infrared. These measurements have led to new HITRAN-style line lists for both 16O2 [3] and rare isotopologue [4] transitions in the A-band. In addition, we have performed detailed line shape studies of CO2 transitions near 1.6 μm under a variety of broadening conditions [5]. We will address recent measurements in these bands as well as highlight recent instrumental improvements to the FS-CRDS spectrometer. These improvements include the use of the Pound-Drever-Hall locking scheme, a high bandwidth servo which enables measurements to be made at rates greater than 10 kHz [6]. In addition, an optical frequency comb will be utilized as a frequency reference, which should allow for transition frequencies to be measured with uncertainties below 10 kHz (3×10-7 cm-1). [1] C. E. Miller, D. Crisp, P. L. DeCola, S. C. Olsen, et al., J. Geophys. Res.-Atmos. 112, D10314 (2007). [2] J. T. Hodges, H. P. Layer, W. W. Miller, G. E. Scace, Rev. Sci. Instrum. 75, 849-863 (2004). [3] D. A. Long, D. K. Havey, M. Okumura, C. E. Miller, et al., J. Quant. Spectrosc. Radiat. Transfer 111, 2021-2036 (2010). [4] D. A. Long, D. K. Havey, S. S. Yu, M. Okumura, et al., J. Quant. Spectrosc

  11. High accuracy digital aging monitor based on PLL-VCO circuit

    NASA Astrophysics Data System (ADS)

    Yuejun, Zhang; Zhidi, Jiang; Pengjun, Wang; Xuelong, Zhang

    2015-01-01

    As the manufacturing process is scaled down to the nanoscale, the aging phenomenon significantly affects the reliability and lifetime of integrated circuits. Consequently, the precise measurement of digital CMOS aging is a key aspect of nanoscale aging tolerant circuit design. This paper proposes a high accuracy digital aging monitor using phase-locked loop and voltage-controlled oscillator (PLL-VCO) circuit. The proposed monitor eliminates the circuit self-aging effect for the characteristic of PLL, whose frequency has no relationship with circuit aging phenomenon. The PLL-VCO monitor is implemented in TSMC low power 65 nm CMOS technology, and its area occupies 303.28 × 298.94 μm2. After accelerating aging tests, the experimental results show that PLL-VCO monitor improves accuracy about high temperature by 2.4% and high voltage by 18.7%.

  12. Measuring changes in Plasmodium falciparum transmission: Precision, accuracy and costs of metrics

    PubMed Central

    Tusting, Lucy S.; Bousema, Teun; Smith, David L.; Drakeley, Chris

    2016-01-01

    As malaria declines in parts of Africa and elsewhere, and as more countries move towards elimination, it is necessary to robustly evaluate the effect of interventions and control programmes on malaria transmission. To help guide the appropriate design of trials to evaluate transmission-reducing interventions, we review eleven metrics of malaria transmission, discussing their accuracy, precision, collection methods and costs, and presenting an overall critique. We also review the non-linear scaling relationships between five metrics of malaria transmission; the entomological inoculation rate, force of infection, sporozoite rate, parasite rate and the basic reproductive number, R0. Our review highlights that while the entomological inoculation rate is widely considered the gold standard metric of malaria transmission and may be necessary for measuring changes in transmission in highly endemic areas, it has limited precision and accuracy and more standardised methods for its collection are required. In areas of low transmission, parasite rate, sero-conversion rates and molecular metrics including MOI and mFOI may be most appropriate. When assessing a specific intervention, the most relevant effects will be detected by examining the metrics most directly affected by that intervention. Future work should aim to better quantify the precision and accuracy of malaria metrics and to improve methods for their collection. PMID:24480314

  13. Estimation of measurement accuracy of track point coordinates in nuclear photoemulsion

    NASA Astrophysics Data System (ADS)

    Shamanov, V. V.

    1995-03-01

    A simple method for an estimation of the measurement accuracy of track point coordinates in nuclear photoemulsion is described. The method is based on analysis of residual deviations of measured track points from a straight line approximating the track. Reliability of the algorithm is illustrated by Monte Carlo simulation. Examples of using the method for an estimation of the accuracy of track point coordinates measured with the microscope KSM-1 (VEB Carl Zeiss Jena) are given.

  14. Evaluation of accuracy of cone beam computed tomography for measurement of periodontal defects: A clinical study

    PubMed Central

    Banodkar, Akshaya Bhupesh; Gaikwad, Rajesh Prabhakar; Gunjikar, Tanay Udayrao; Lobo, Tanya Arthur

    2015-01-01

    Aims: The aim of the present study was to evaluate the accuracy of Cone Beam Computed Tomography (CBCT) measurements of alveolar bone defects caused due to periodontal disease, by comparing it with actual surgical measurements which is the gold standard. Materials and Methods: Hundred periodontal bone defects in fifteen patients suffering from periodontitis and scheduled for flap surgery were included in the study. On the day of surgery prior to anesthesia, CBCT of the quadrant to be operated was taken. After reflection of the flap, clinical measurements of periodontal defect were made using a reamer and digital vernier caliper. The measurements taken during surgery were then compared to the measurements done with CBCT and subjected to statistical analysis using the Pearson's correlation test. Results: Overall there was a very high correlation of 0.988 between the surgical and CBCT measurements. In case of type of defects the correlation was higher in horizontal defects as compared to vertical defects. Conclusions: CBCT is highly accurate in measurement of periodontal defects and proves to be a very useful tool in periodontal diagnosis and treatment assessment. PMID:26229268

  15. Key technologies for high-accuracy large mesh antenna reflectors

    NASA Astrophysics Data System (ADS)

    Meguro, Akira; Harada, Satoshi; Watanabe, Mitsunobu

    2003-12-01

    Nippon Telephone and Telegram Corporation (NTT) continues to develop the modular mesh-type deployable antenna. Antenna diameter can be changed from 5 m to about 20 m by changing the number of modules used with surface accuracy better than 2.4 mm RMS (including all error factors) with sufficient deployment reliability. Key technologies are the antenna's structural design, the deployment mechanism, the design tool, the analysis tool, and modularized testing/evaluation methods. This paper describes our beam steering mechanism. Tests show that it yields a beam pointing accuracy of better than 0.1°. Based on the S-band modular mesh antenna reflector, the surface accuracy degradation factors that must be considered in designing the new antenna are partially identified. The influence of modular connection errors on surface accuracy is quantitatively estimated. Our analysis tool SPADE is extended to include the addition of joint gaps. The addition of gaps allows non-linear vibration characteristics due to gapping in deployment hinges to be calculated. We intend to design a new type of mesh antenna reflector. Our new goal is an antenna for Ku or Ka band satellite communication. For this mission, the surface shape must be 5 times more accurate than is required for an S-band antenna.

  16. Military applications of high-accuracy frequency standards and clocks

    NASA Astrophysics Data System (ADS)

    Vig, John R.

    1993-08-01

    Frequency control and timing devices are essential components in modern military electronics systems. Reviewed in this paper are the applications of these devices, and the manner in which the stability and accuracy of these devices impact the performance of military communication, navigation, surveillance, electronic warfare, missile guidance, and identification-friend-or-foe systems.

  17. Line-shapes analysis with ultra-high accuracy

    NASA Astrophysics Data System (ADS)

    Wcisło, Piotr; Cygan, Agata; Lisak, Daniel; Ciuryło, Roman

    2014-11-01

    We present analysis of the R7 Q8 O2 B-band rovibronic transition measured with ultra-high signal-to-noise ratio by Pound-Drever-Hall-locked frequency-stabilized cavity-ring- down spectroscopy. For line-shape calculations ab intio in spirt approach was used based on numerical solution of the proper transport/relaxation equation. Consequences for spectroscopic determination of the Boltzmann constant as well as precise determination of the line position in the Doppler limited spectroscopy are indicated.

  18. The Discriminant Accuracy of a Grammatical Measure with Latino English-Speaking Children

    ERIC Educational Resources Information Center

    Gutierrez-Clellen, Vera F.; Simon-Cereijido, Gabriela

    2007-01-01

    Purpose: To evaluate the discriminant accuracy of a grammatical measure for the identification of language impairment (LI) in Latino English-speaking children. Specifically, the study examined the diagnostic accuracy of the Test of English Morphosyntax (E-MST; Pena, Gutierrez-Clellen, Iglesias, Goldstein, & Bedore (n.d.) to determine (a) whether…

  19. Effect of Lossy JPEG Compression of an Image with Chromatic Aberrations on Target Measurement Accuracy

    NASA Astrophysics Data System (ADS)

    Matsuoka, R.

    2014-05-01

    This paper reports an experiment conducted to investigate the effect of lossy JPEG compression of an image with chromatic aberrations on the measurement accuracy of target center by the intensity-weighted centroid method. I utilized six images shooting a white sheet with 30 by 20 black filled circles in the experiment. The images were acquired by a digital camera Canon EOS 20D. The image data were compressed by using two compression parameter sets of a downsampling ratio, a quantization table and a Huffman code table utilized in EOS 20D. The experiment results clearly indicate that lossy JPEG compression of an image with chromatic aberrations would produce a significant effect on measurement accuracy of target center by the intensity-weighted centroid method. The maximum displacements of red, green and blue components caused by lossy JPEG compression were 0.20, 0.09, and 0.20 pixels respectively. The results also suggest that the downsampling of the chrominance components Cb and Cr in lossy JPEG compression would produce displacements between uncompressed image data and compressed image data. In conclusion, since the author consider that it would be unable to correct displacements caused by lossy JPEG compression, the author would recommend that lossy JPEG compression before recording an image in a digital camera should not be executed in case of highly precise image measurement by using color images acquired by a non-metric digital camera.

  20. Accuracy and reliability of measurements obtained from computed tomography 3D volume rendered images.

    PubMed

    Stull, Kyra E; Tise, Meredith L; Ali, Zabiullah; Fowler, David R

    2014-05-01

    Forensic pathologists commonly use computed tomography (CT) images to assist in determining the cause and manner of death as well as for mass disaster operations. Even though the design of the CT machine does not inherently produce distortion, most techniques within anthropology rely on metric variables, thus concern exists regarding the accuracy of CT images reflecting an object's true dimensions. Numerous researchers have attempted to validate the use of CT images, however the comparisons have only been conducted on limited elements and/or comparisons were between measurements taken from a dry element and measurements taken from the 3D-CT image of the same dry element. A full-body CT scan was performed prior to autopsy at the Office of the Chief Medical Examiner for the State of Maryland. Following autopsy, the remains were processed to remove all soft tissues and the skeletal elements were subject to an additional CT scan. Percent differences and Bland-Altman plots were used to assess the accuracy between osteometric variables obtained from the dry skeletal elements and from CT images with and without soft tissues. An additional seven crania were scanned, measured by three observers, and the reliability was evaluated by technical error of measurement (TEM) and relative technical error of measurement (%TEM). Average percent differences between the measurements obtained from the three data sources ranged from 1.4% to 2.9%. Bland-Altman plots illustrated the two sets of measurements were generally within 2mm for each comparison between data sources. Intra-observer TEM and %TEM for three observers and all craniometric variables ranged between 0.46mm and 0.77mm and 0.56% and 1.06%, respectively. The three-way inter-observer TEM and %TEM for craniometric variables was 2.6mm and 2.26%, respectively. Variables that yielded high error rates were orbital height, orbital breadth, inter-orbital breadth and parietal chord. Overall, minimal differences were found among the

  1. Intercomparison of silicon dioxide thickness measurements made by multiple techniques: The route to accuracy

    NASA Astrophysics Data System (ADS)

    Seah, M. P.

    2004-07-01

    A pilot project has been launched under the auspices of the Consultative Committee for Amount of Substance to evaluate the quantification for SiO2 on (100) and (111) Si in the thickness range 1.5-8 nm. Wafers and methodologies have been carefully prepared. Forty-five sets of measurements have been made in different laboratories using eight methods: medium energy ion scattering spectrometry (MEIS), nuclear reaction analysis (NRA), Rutherford backscattering spectrometry (RBS), elastic backscattering spectrometry (EBS), x-ray photoelectron spectroscopy (XPS), ellipsometry, grazing incidence x-ray reflectometry (GIXRR), neutron reflectometry (NR), and transmission electron microscopy. The results have been assessed, against the National Physical Laboratory (NPL) XPS data, using d(respondee)=md(NPL)+c. All show excellent linearity. The main sets correlate with the NPL data with average root-mean-square scatters of 0.13 nm with half being <0.1 nm. Each set allows the relative scaling constant, m, and the zero thickness offset, c to be determined. Each method has 0measured here, that have caused many problems in the past. Each technique has a different accuracy for m and consistent results have been achieved. XPS has poor accuracy for m but a high precision and, critically, has zero offset if used correctly. Achieving a consistent scaling constant and zero offset for XPS requires reference conditions that dramatically improve data consistency and validity. A combination of XPS and other methods allows an accurate determination of the XPS scaling constant, m=0.986+/-0.004. XPS may then have an uncertainty approaching 2%, traceable via other methods. NR, GIXRR, MEIS, NRA, RBS, and EBS have small offsets which, if they can be controlled, will enable these methods also to be used with high accuracy. .

  2. Accuracy and reliability of linear measurements using tangential projection and cone beam computed tomography

    PubMed Central

    Sheikhi, Mahnaz; Dakhil-Alian, Mansour; Bahreinian, Zahra

    2015-01-01

    Background: Providing a cross-sectional image is essential for preimplant assessments. Computed tomography (CT) and cone beam CT (CBCT) images are very expensive and provide high radiation dose. Tangential projection is a very simple, available, and low-dose technique that can be used in the anterior portion of mandible. The purpose of this study was to evaluate the accuracy of tangential projection in preimplant measurements in comparison to CBCT. Materials and Methods: Three dry edentulous human mandibles were examined in five points at intercanine region using tangential projection and CBCT. The height and width of the ridge were measured twice by two observers. The mandibles were then cut, and real measurements were obtained. The agreement between real measures and measurements obtained by either technique, and inter- and intra-observer reliability were tested. Results: The measurement error was less than 0.12 for tangential technique and 0.06 for CBCT. The agreement between the real measures and measurements from radiographs were higher than 0.87. Tangential projection slightly overestimated the distances, while there was a slight underestimation in CBCT results. Conclusion: Considering the low cost, low radiation dose, simplicity and availability, tangenital projection would be adequate for preimplant assessment in edentulous patients when limited numbers of implants are required in the anterior mandible. PMID:26005469

  3. A high accuracy all-angle gyroscope readout using quantized flux

    NASA Technical Reports Server (NTRS)

    Anderson, J. T.; Everitt, C. W. F.

    1977-01-01

    Means are described to use SQUID magnetometer flux counting and the London moment of a spherical superconducting gyroscope to read out the gyroscope spin axis direction to an accuracy of at least 23 bits per quadrant. The system is discussed in analogy to optical fringe counting as applied to distance measurement. Several methods of applying both analog and digital SQUID magnetometers to the readout problem are given, as well as limitations on each. Described are two methods of increasing the flux available for measurement: magnetizing the gyroscope with a trapped field, and optimizing readout circuit inductances. Finally, the same principle on which the gyroscope readout is based is applied to a description of a high accuracy, flux counting, digital angle encoder.

  4. One high-accuracy camera calibration algorithm based on computer vision images

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Huang, Jianming; Wei, Xiangquan

    2015-12-01

    Camera calibration is the first step of computer vision and one of the most active research fields nowadays. In order to improve the measurement precision, the internal parameters of the camera should be accurately calibrated. So one high-accuracy camera calibration algorithm is proposed based on the images of planar targets or tridimensional targets. By using the algorithm, the internal parameters of the camera are calibrated based on the existing planar target at the vision-based navigation experiment. The experimental results show that the accuracy of the proposed algorithm is obviously improved compared with the conventional linear algorithm, Tsai general algorithm, and Zhang Zhengyou calibration algorithm. The algorithm proposed by the article can satisfy the need of computer vision and provide reference for precise measurement of the relative position and attitude.

  5. Influence of measurement conditions and system parameters on accuracy of remote temperature measurement with dualspectral IR systems

    NASA Astrophysics Data System (ADS)

    Chrzanowski, K.

    1996-04-01

    A theory of the influence of measurement conditions and system parameters on the accuracy of remote temperature measurements with dualspectral IR systems has been developed. An analysis of the influence of the disturbances of the measurement process caused by system noise, spectrally variable emissivity of the tested object, radiation reflected by the object, limited transmittance of the atmosphere, and radiation emitted by the filters and the optics on the accuracy of the dualspectral IR systems has been made using this theory. The results show that the accuracy definitively depends on the measurement conditions and the system parameters.

  6. Composite low-coherence interferometer for imaging of immersed tissue with high accuracy

    NASA Astrophysics Data System (ADS)

    Chang, Chun-Wei; Hsu, I.-Jen

    2012-09-01

    Imaging and measurement of the surface profile of an object with high resolution has become essential in both of biological research and industry application. Many samples under investigation such as cultured cells are usually immersed in liquid. Although the techniques such as scanning electron microscope and atomic force microscope can provide imaging or measurement of the surface profile with nanometer resolution, it is difficult for them to image an immersed object with their typical types. Recently, we have proposed and demonstrated a new technique based on composite interferometer which can perform imaging and measurement of the surface profile of an object with accuracy in the axial direction within 5 nm through a self-phase-compensation mechanism. In this research, an optical system based on the concept of combination of optical coherence microscopy (OCM) and composite interferometer was built for imaging of biological tissue immersed in water with axial accuracy at nanometer scale. In the system, a Ti:sapphire laser with center wavelength at 800 nm and spectral width of 140 nm was used as the light source. The composite interferometer comprises two Michelson interferometers sharing common light source, reference arm and photodetector. One of the two interferometers served as a typical OCM system and the other was used to measure the phase shift in the reference arm in each axial scan with the sample being a fixed reflection mirror. The system was used to image the surface profiles of various immersed biological samples with accuracy at nanometer scale through the self-phasecompensation mechanism.

  7. Ultra-high accuracy optical testing: creating diffraction-limitedshort-wavelength optical systems

    SciTech Connect

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Rekawa, Senajith B.; Denham, Paul E.; Liddle, J. Alexander; Gullikson, Eric M.; Jackson, KeithH.; Anderson, Erik H.; Taylor, John S.; Sommargren, Gary E.; Chapman,Henry N.; Phillion, Donald W.; Johnson, Michael; Barty, Anton; Soufli,Regina; Spiller, Eberhard A.; Walton, Christopher C.; Bajt, Sasa

    2005-08-03

    Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-{angstrom} and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date.

  8. High-accuracy position-sensing with fiber-coupled white-light interferometers

    NASA Astrophysics Data System (ADS)

    Bosselmann, Th.; Ulrich, R.

    A fiber-optic system for high-accuracy position sensing has been constructed using the principle of white-light interferometry. In the system, white light from a W-lamp is fed via multimode optical fibers consecutively through two conventional Michelson interferometers to a detector. The element whose position is to be sensed displaces one mirror of the transmitting interferometer in the sensor head; the receiving interferometer, located in a remote control room, is scanned periodically, and the appearance of white-light fringes is used to mark the coincidence of the optical path differences. To measure the transmitted positions, a HeNe laser beam is fed additionally through the receiving interferometer and the fringes are counted. The system provides the usual high accuracy of laser interferometers, yet it does not 'forget' its zero point when interrupted. The use of multimode fibers provides enough optical power to permit operation multiplex of several simple transmitters with a single, more sophisticated receiver.

  9. Precision and accuracy of spectrophotometric pH measurements at environmental conditions in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Hammer, Karoline; Schneider, Bernd; Kuliński, Karol; Schulz-Bull, Detlef E.

    2014-06-01

    The increasing uptake of anthropogenic CO2 by the oceans has raised an interest in precise and accurate pH measurement in order to assess the impact on the marine CO2-system. Spectrophotometric pH measurements were refined during the last decade yielding a precision and accuracy that cannot be achieved with the conventional potentiometric method. However, until now the method was only tested in oceanic systems with a relative stable and high salinity and a small pH range. This paper describes the first application of such a pH measurement system at conditions in the Baltic Sea which is characterized by a wide salinity and pH range. The performance of the spectrophotometric system at pH values as low as 7.0 (“total” scale) and salinities between 0 and 35 was examined using TRIS-buffer solutions, certified reference materials, and tests of consistency with measurements of other parameters of the marine CO2 system. Using m-cresol purple as indicator dye and a spectrophotometric measurement system designed at Scripps Institution of Oceanography (B. Carter, A. Dickson), a precision better than ±0.001 and an accuracy between ±0.01 and ±0.02 was achieved within the observed pH and salinity ranges in the Baltic Sea. The influence of the indicator dye on the pH of the sample was determined theoretically and is presented as a pH correction term for the different alkalinity regimes in the Baltic Sea. Because of the encouraging tests, the ease of operation and the fact that the measurements refer to the internationally accepted “total” pH scale, it is recommended to use the spectrophotometric method also for pH monitoring and trend detection in the Baltic Sea.

  10. Techniques for improving the accuracy of cyrogenic temperature measurement in ground test programs

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Fabik, Richard H.

    1993-01-01

    The performance of a sensor is often evaluated by determining to what degree of accuracy a measurement can be made using this sensor. The absolute accuracy of a sensor is an important parameter considered when choosing the type of sensor to use in research experiments. Tests were performed to improve the accuracy of cryogenic temperature measurements by calibration of the temperature sensors when installed in their experimental operating environment. The calibration information was then used to correct for temperature sensor measurement errors by adjusting the data acquisition system software. This paper describes a method to improve the accuracy of cryogenic temperature measurements using corrections in the data acquisition system software such that the uncertainty of an individual temperature sensor is improved from plus or minus 0.90 deg R to plus or minus 0.20 deg R over a specified range.

  11. High Accuracy, Two-Dimensional Read-Out in Multiwire Proportional Chambers

    DOE R&D Accomplishments Database

    Charpak, G.; Sauli, F.

    1973-02-14

    In most applications of proportional chambers, especially in high-energy physics, separate chambers are used for measuring different coordinates. In general one coordinate is obtained by recording the pulses from the anode wires around which avalanches have grown. Several methods have been imagined for obtaining the position of an avalanche along a wire. In this article a method is proposed which leads to the same range of accuracies and may be preferred in some cases. The problem of accurate measurements for large-size chamber is also discussed.

  12. Parallel Reaction Monitoring: A Targeted Experiment Performed Using High Resolution and High Mass Accuracy Mass Spectrometry

    PubMed Central

    Rauniyar, Navin

    2015-01-01

    The parallel reaction monitoring (PRM) assay has emerged as an alternative method of targeted quantification. The PRM assay is performed in a high resolution and high mass accuracy mode on a mass spectrometer. This review presents the features that make PRM a highly specific and selective method for targeted quantification using quadrupole-Orbitrap hybrid instruments. In addition, this review discusses the label-based and label-free methods of quantification that can be performed with the targeted approach. PMID:26633379

  13. Detection techniques in low-coherence interferometry and their impact on overall measurement accuracy.

    PubMed

    Pikálek, Tomáš; Fořt, Tomáš; Buchta, Zdeněk

    2014-12-20

    This paper deals with interference fringe center detection techniques used in low-coherence interferometry for contactless 3D inspection of macroscopic objects. It presents a complex analysis of several frequently used detection techniques and shows their impact on the measurement accuracy. The analysis compares those techniques in terms of computational complexity, measurement accuracy, and resistance to optical dispersion caused by wedge-shaped optical components. PMID:25608195

  14. Accuracy assessment of airborne photogrammetrically derived high-resolution digital elevation models in a high mountain environment

    NASA Astrophysics Data System (ADS)

    Müller, Johann; Gärtner-Roer, Isabelle; Thee, Patrick; Ginzler, Christian

    2014-12-01

    High-resolution digital elevation models (DEMs) generated by airborne remote sensing are frequently used to analyze landform structures (monotemporal) and geomorphological processes (multitemporal) in remote areas or areas of extreme terrain. In order to assess and quantify such structures and processes it is necessary to know the absolute accuracy of the available DEMs. This study assesses the absolute vertical accuracy of DEMs generated by the High Resolution Stereo Camera-Airborne (HRSC-A), the Leica Airborne Digital Sensors 40/80 (ADS40 and ADS80) and the analogue camera system RC30. The study area is located in the Turtmann valley, Valais, Switzerland, a glacially and periglacially formed hanging valley stretching from 2400 m to 3300 m a.s.l. The photogrammetrically derived DEMs are evaluated against geodetic field measurements and an airborne laser scan (ALS). Traditional and robust global and local accuracy measurements are used to describe the vertical quality of the DEMs, which show a non Gaussian distribution of errors. The results show that all four sensor systems produce DEMs with similar accuracy despite their different setups and generations. The ADS40 and ADS80 (both with a ground sampling distance of 0.50 m) generate the most accurate DEMs in complex high mountain areas with a RMSE of 0.8 m and NMAD of 0.6 m They also show the highest accuracy relating to flying height (0.14‰). The pushbroom scanning system HRSC-A produces a RMSE of 1.03 m and a NMAD of 0.83 m (0.21‰ accuracy of the flying height and 10 times the ground sampling distance). The analogue camera system RC30 produces DEMs with a vertical accuracy of 1.30 m RMSE and 0.83 m NMAD (0.17‰ accuracy of the flying height and two times the ground sampling distance). It is also shown that the performance of the DEMs strongly depends on the inclination of the terrain. The RMSE of areas up to an inclination <40° is better than 1 m. In more inclined areas the error and outlier occurrence

  15. 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

  16. Increasing the accuracy of measurements based on the solution of Pauli's quantum equation

    NASA Astrophysics Data System (ADS)

    Ermishin, Sergey; Korol, Alexandra

    2013-05-01

    There is a measurements principle that ensures the increase of accuracy of measurements based on redundant measurements. Main properties of the solution are: a discrete method with a surge of probability within the parent entity and comparison of the graph of the probability distribution for the diffraction grids with the graph of probability density function. Method based on the analog of Pauli equation solution. The method of electronic reference measurements with quantum computing applied to mathematical data processing allows to greatly increase the credibility and accuracy of measurements at low cost, which is confirmed by simulation.

  17. Characterization of geolocation accuracy of Suomi NPP Advanced Technology Microwave Sounder measurements

    NASA Astrophysics Data System (ADS)

    Han, Yang; Weng, Fuzhong; Zou, Xiaolei; Yang, Hu; Scott, Deron

    2016-05-01

    The Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar-orbiting Partnership satellite has 22 channels at frequencies ranging from 23 to 183 GHz for probing the atmospheric temperature and moisture under all weather conditions. As part of the ATMS calibration and validation activities, the geolocation accuracy of ATMS data must be well characterized and documented. In this study, the coastline crossing method (CCM) and the land-sea fraction method (LFM) are utilized to characterize and quantify the ATMS geolocation accuracy. The CCM is based on the inflection points of the ATMS window channel measurements across the coastlines, whereas the LFM collocates the ATMS window channel data with high-resolution land-sea mask data sets. Since the ATMS measurements provide five pairs of latitude and longitude data for K, Ka, V, W, and G bands, respectively, the window channels 1, 2, 3, 16, and 17 from each of these five bands are chosen for assessing the overall geolocation accuracy. ATMS geolocation errors estimated from both methods are generally consistent from 40 cases in June 2014. The ATMS along-track (cross-track) errors at nadir are within ±4.2 km (±1.2 km) for K/Ka, ±2.6 km (±2.7 km) for V bands, and ±1.2 km (±0.6 km) at W and G bands, respectively. At the W band, the geolocation errors derived from both algorithms are probably less reliable due to a reduced contrast of brightness temperatures in coastal areas. These estimated ATMS along-track and cross-track geolocation errors are well within the uncertainty requirements for all bands.

  18. A Smart High Accuracy Silicon Piezoresistive Pressure Sensor Temperature Compensation System

    PubMed Central

    Zhou, Guanwu; Zhao, Yulong; Guo, Fangfang; Xu, Wenju

    2014-01-01

    Theoretical analysis in this paper indicates that the accuracy of a silicon piezoresistive pressure sensor is mainly affected by thermal drift, and varies nonlinearly with the temperature. Here, a smart temperature compensation system to reduce its effect on accuracy is proposed. Firstly, an effective conditioning circuit for signal processing and data acquisition is designed. The hardware to implement the system is fabricated. Then, a program is developed on LabVIEW which incorporates an extreme learning machine (ELM) as the calibration algorithm for the pressure drift. The implementation of the algorithm was ported to a micro-control unit (MCU) after calibration in the computer. Practical pressure measurement experiments are carried out to verify the system's performance. The temperature compensation is solved in the interval from −40 to 85 °C. The compensated sensor is aimed at providing pressure measurement in oil-gas pipelines. Compared with other algorithms, ELM acquires higher accuracy and is more suitable for batch compensation because of its higher generalization and faster learning speed. The accuracy, linearity, zero temperature coefficient and sensitivity temperature coefficient of the tested sensor are 2.57% FS, 2.49% FS, 8.1 × 10−5/°C and 29.5 × 10−5/°C before compensation, and are improved to 0.13%FS, 0.15%FS, 1.17 × 10−5/°C and 2.1 × 10−5/°C respectively, after compensation. The experimental results demonstrate that the proposed system is valid for the temperature compensation and high accuracy requirement of the sensor. PMID:25006998

  19. Optical System Error Analysis and Calibration Method of High-Accuracy Star Trackers

    PubMed Central

    Sun, Ting; Xing, Fei; You, Zheng

    2013-01-01

    The star tracker is a high-accuracy attitude measurement device widely used in spacecraft. Its performance depends largely on the precision of the optical system parameters. Therefore, the analysis of the optical system parameter errors and a precise calibration model are crucial to the accuracy of the star tracker. Research in this field is relatively lacking a systematic and universal analysis up to now. This paper proposes in detail an approach for the synthetic error analysis of the star tracker, without the complicated theoretical derivation. This approach can determine the error propagation relationship of the star tracker, and can build intuitively and systematically an error model. The analysis results can be used as a foundation and a guide for the optical design, calibration, and compensation of the star tracker. A calibration experiment is designed and conducted. Excellent calibration results are achieved based on the calibration model. To summarize, the error analysis approach and the calibration method are proved to be adequate and precise, and could provide an important guarantee for the design, manufacture, and measurement of high-accuracy star trackers. PMID:23567527

  20. Optical system error analysis and calibration method of high-accuracy star trackers.

    PubMed

    Sun, Ting; Xing, Fei; You, Zheng

    2013-01-01

    The star tracker is a high-accuracy attitude measurement device widely used in spacecraft. Its performance depends largely on the precision of the optical system parameters. Therefore, the analysis of the optical system parameter errors and a precise calibration model are crucial to the accuracy of the star tracker. Research in this field is relatively lacking a systematic and universal analysis up to now. This paper proposes in detail an approach for the synthetic error analysis of the star tracker, without the complicated theoretical derivation. This approach can determine the error propagation relationship of the star tracker, and can build intuitively and systematically an error model. The analysis results can be used as a foundation and a guide for the optical design, calibration, and compensation of the star tracker. A calibration experiment is designed and conducted. Excellent calibration results are achieved based on the calibration model. To summarize, the error analysis approach and the calibration method are proved to be adequate and precise, and could provide an important guarantee for the design, manufacture, and measurement of high-accuracy star trackers. PMID:23567527

  1. Design and performance of a new high accuracy combined small sample neutron/gamma detector

    SciTech Connect

    Menlove, H.; Davidson, D.; Verplancke, J.; Vermeulen, P.; Wagner, H.G.; Wellum, R.; Brandelise, B.; Mayer, K.

    1993-08-01

    This paper describes the design of an optimized combined neutron and gamma detector installed around a measurement well protruding from the floor of a glove box. The objective of this design was to achieve an overall accuracy for the plutonium element concentration in gram-sized samples of plutonium oxide powder approaching the {approximately}0.1--0.2% accuracies routinely achieved by inspectors` chemical analysis. The efficiency of the clam-shell neutron detector was increased and the flat response zone extended in axial and radial directions. The sample holder introduced from within the glove box was designed to form the upper reflector, while two graphite half-shells fitted around the thin neck of the high-resolution LEGE detector replaced the lower plug. The Institute for Reference Materials and Measurements (IRMM) in Geel prepared special plutonium oxide test samples whose plutonium concentration was determined to better than 0.05%. During a three week initial performance test in July 1992 at ITU Karlsruhe and in long term tests, it was established that the target accuracy can be achieved provided sufficient care is taken to assure the reproducibility of sample bottling and sample positioning. The paper presents and discusses the results of all test measurements.

  2. Design and performance of a new high accuracy combined small sample neutron/gamma detector

    SciTech Connect

    Menlove, H.; Davidson, D.; Verplancke, J.; Vermeulen, P.; Wagner, H.G.; Wellum, R.; Brandelise, B.; Mayer, K.

    1993-12-31

    This paper describes the design of an optimized combined neutron and gamma detector installed around a measurement well protruding from the floor of a glove box. The objective of this design was to achieve an overall accuracy for the plutonium element concentration in gram-sized samples of plutonium oxide powder approaching the {approximately}0.1--0.2% accuracies routinely achieved by inspectors` chemical analysis. The efficiency of the clam-shell neutron detector was increased and the flat response zone extended in axial and radial directions. The sample holder introduced from within the glove box was designed to form the upper reflector, while two graphite half-shells fitted around the thin neck of the high-resolution LEGe detector replaced the lower plug. The Institute for Reference Materials and Measurements (IRMM) in Geel prepared special plutonium oxide test samples whose plutonium concentration was determined to better than 0.05%. During a three week initial performance test in July 1992 at ITU Karlsruhe and in long term tests, it was established that the target accuracy can be achieved provided sufficient care is taken to assure the reproducibility of sample bottling and sample positioning. The paper presents and discusses the results of all test measurements.

  3. Accuracy of quantum sensors measuring yield photon flux and photosynthetic photon flux

    NASA Technical Reports Server (NTRS)

    Barnes, C.; Tibbitts, T.; Sager, J.; Deitzer, G.; Bubenheim, D.; Koerner, G.; Bugbee, B.; Knott, W. M. (Principal Investigator)

    1993-01-01

    Photosynthesis is fundamentally driven by photon flux rather than energy flux, but not all absorbed photons yield equal amounts of photosynthesis. Thus, two measures of photosynthetically active radiation have emerged: photosynthetic photon flux (PPF), which values all photons from 400 to 700 nm equally, and yield photon flux (YPF), which weights photons in the range from 360 to 760 nm according to plant photosynthetic response. We selected seven common radiation sources and measured YPF and PPF from each source with a spectroradiometer. We then compared these measurements with measurements from three quantum sensors designed to measure YPF, and from six quantum sensors designed to measure PPF. There were few differences among sensors within a group (usually <5%), but YPF values from sensors were consistently lower (3% to 20%) than YPF values calculated from spectroradiometric measurements. Quantum sensor measurements of PPF also were consistently lower than PPF values calculated from spectroradiometric measurements, but the differences were <7% for all sources, except red-light-emitting diodes. The sensors were most accurate for broad-band sources and least accurate for narrow-band sources. According to spectroradiometric measurements, YPF sensors were significantly less accurate (>9% difference) than PPF sensors under metal halide, high-pressure sodium, and low-pressure sodium lamps. Both sensor types were inaccurate (>18% error) under red-light-emitting diodes. Because both YPF and PPF sensors are imperfect integrators, and because spectroradiometers can measure photosynthetically active radiation much more accurately, researchers should consider developing calibration factors from spectroradiometric data for some specific radiation sources to improve the accuracy of integrating sensors.

  4. A Quest for Measuring Ion Bunch Longitudinal Profiles with One Picosecond Accuracy in the SNS Linac.

    SciTech Connect

    Aleksandrov, Alexander V; Dickson, Richard W

    2012-01-01

    The SNS linac utilizes several accelerating structures operating at different frequencies and with different transverse focusing structures. Low-loss beam transport requires a careful matching at the transition points in both the transverse and longitudinal axes. Longitudinal beam parameters are measured using four Bunch Shape Monitors (used at many ion accelerator facilities, aka Feschenko devices). These devices, as initially delivered to the SNS, provided an estimated accuracy of about 5 picoseconds, which was sufficient for the initial beam commissioning. New challenges of improving beam transport for higher power operation will require measuring bunch profiles with 1-2 picoseconds accuracy. We have successfully implemented a number of improvements to maximize the performance characteristics of the delivered devices. We will discuss the current status of this instrument, its ultimate theoretical limit of accuracy, and how we measure its accuracy and resolution with real beam conditions.

  5. Accuracy of Computerized Vertical Measurements on Digital Orthopantomographs: Posterior Mandibular Region

    PubMed Central

    Assaf, Mohammad; Gharbyah, Alaa’ Z. Abu

    2014-01-01

    Objectives: Orthopantomographs are commonly used for diagnosis in clinical dentistry. Although the manufacturers claim a constant magnification effect, the reliability of measuring dimensions on the panoramic radiographs is not clear. The aim of this study was to evaluate the accuracy of measuring vertical dimensions in the posterior mandibular area on digital orthopantomographs. Materials and Methods: A retrospective survey of 20 orthopantomographs with unrestored implants (only with cover screw) in the mandibular posterior region (molars and premolars) was conducted. All radiographs were taken using the same machine by skilled technicians. Two examiners were asked to measure the vertical dimension of the implants seen on the radiographs viewed using two differently sized display screens. Inter-examiner and intra-examiner reliability tests were performed. Differences between the measured length and the actual length using each screen type were compared. Results: High coefficients of reliability were observed on intra- and inter-examiner correlation. The overall reliability of measuring the vertical dimensions of implants between both examiners for the large screen and the small screen were 97.4% (Cronbach's alpha 0.993) and 94.0% (Cronbach's alpha 0.984), respectively. There were no significant differences between the errors seen with either the large screen or the small screen, when each of them was compared to the original length (P = 0.146). Conclusion: This study shows that vertical dimensions in the posterior mandibular region (molar and premolars) can be reliably measured on an orthopantomograph using a calibrated machine and special software. PMID:25806135

  6. Experimental verification of a theory of the influence of measurement conditions on temperature measurement accuracy with IR systems

    NASA Astrophysics Data System (ADS)

    Chrzanowski, Krzysztof

    1996-07-01

    A theory of the influence of measurement conditions on temperature measurement accuracy with infrared systems has been recently presented. A comparison study of the shortwave (3-5- mu m) and longwave (8-12- mu m) measuring IR cameras was conducted on the basis of this theory. The results of the simulations show that the shortwave systems in typical measurement conditions generally offer better accuracy in temperature measurement than do the longwave systems. Some experiments that use a commercially available IR camera were carried out to verify the theory. The results of these experiments and a discussion about the theory limitations are presented. temperature measurement.

  7. Accuracy Assessment and Correction of Vaisala RS92 Radiosonde Water Vapor Measurements

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Miloshevich, Larry M.; Vomel, Holger; Leblanc, Thierry

    2008-01-01

    Relative humidity (RH) measurements from Vaisala RS92 radiosondes are widely used in both research and operational applications, although the measurement accuracy is not well characterized as a function of its known dependences on height, RH, and time of day (or solar altitude angle). This study characterizes RS92 mean bias error as a function of its dependences by comparing simultaneous measurements from RS92 radiosondes and from three reference instruments of known accuracy. The cryogenic frostpoint hygrometer (CFH) gives the RS92 accuracy above the 700 mb level; the ARM microwave radiometer gives the RS92 accuracy in the lower troposphere; and the ARM SurTHref system gives the RS92 accuracy at the surface using 6 RH probes with NIST-traceable calibrations. These RS92 assessments are combined using the principle of Consensus Referencing to yield a detailed estimate of RS92 accuracy from the surface to the lowermost stratosphere. An empirical bias correction is derived to remove the mean bias error, yielding corrected RS92 measurements whose mean accuracy is estimated to be +/-3% of the measured RH value for nighttime soundings and +/-4% for daytime soundings, plus an RH offset uncertainty of +/-0.5%RH that is significant for dry conditions. The accuracy of individual RS92 soundings is further characterized by the 1-sigma "production variability," estimated to be +/-1.5% of the measured RH value. The daytime bias correction should not be applied to cloudy daytime soundings, because clouds affect the solar radiation error in a complicated and uncharacterized way.

  8. The static accuracy and calibration of inertial measurement units for 3D orientation.

    PubMed

    Brodie, M A; Walmsley, A; Page, W

    2008-12-01

    Inertial measurement units (IMUs) are integrated electronic devices that contain accelerometers, magnetometers and gyroscopes. Wearable motion capture systems based on IMUs have been advertised as alternatives to optical motion capture. In this paper, the accuracy of five different IMUs of the same type in measuring 3D orientation in static situations, as well as the calibration of the accelerometers and magnetometers within the IMUs, has been investigated. The maximum absolute static orientation error was 5.2 degrees , higher than the 1 degrees claimed by the vendor. If the IMUs are re-calibrated at the time of measurement with the re-calibration procedure described in this paper, it is possible to obtain an error of less than 1 degrees , in agreement with the vendor's specifications (XSens Technologies B.V. 2005. Motion tracker technical documentation Mtx-B. Version 1.03. Available from: www.xsens.com). The new calibration appears to be valid for at least 22 days providing the sensor is not exposed to high impacts. However, if several sensors are 'daisy chained' together changes to the magnetometer bias can cause heading errors of up to 15 degrees . The results demonstrate the non-linear relationship between the vendor's orthogonality claim of < 0.1 degrees and the accuracy of 3D orientation obtained from factory calibrated IMUs in static situations. The authors hypothesise that the high magnetic dip (64 degrees ) in our laboratory may have exacerbated the errors reported. For biomechanical research, small relative movements of a body segment from a calibrated position are likely to be more accurate than large scale global motion that may have an error of up to 9.8 degrees . PMID:18688763

  9. Accuracy of High-Rate GPS for Seismology

    NASA Technical Reports Server (NTRS)

    Elosegui, P.; Davis, J. L.; Oberlander, D.; Baena, R.; Ekstrom, G.

    2006-01-01

    We built a device for translating a GPS antenna on a positioning table to simulate the ground motions caused by an earthquake. The earthquake simulator is accurate to better than 0.1 mm in position, and provides the "ground truth" displacements for assessing the technique of high-rate GPS. We found that the root-mean-square error of the 1-Hz GPS position estimates over the 15-min duration of the simulated seismic event was 2.5 mm, with approximately 96% of the observations in error by less than 5 mm, and is independent of GPS antenna motion. The error spectrum of the GPS estimates is approximately flicker noise, with a 50% decorrelation time for the position error of approx.1.6 s. We that, for the particular event simulated, the spectrum of dependent error in the GPS measurements. surface deformations exceeds the GPS error spectrum within a finite band. More studies are required to determine whether a generally optimal bandwidth exists for a target group of seismic events.

  10. A novel high accuracy 3D scanning device for rock-art sites

    NASA Astrophysics Data System (ADS)

    Höll, T.; Holler, G.; Pinz, A.

    2014-06-01

    We are currently developing a novel 3D scanning device for rock-art. Within the European project 3D-Pitoti, this scanner shall be used to acquire 3D structure and radiometric surface properties of ancient rock-art sites in Valcamonica. Overall design goals include high spatial accuracy and precision, as well as radiometric quality beyond phototexture. This paper is devoted to the geometric measurement principle of the new scanner. We present a novel scanning scheme based on various constraints to Structure from Motion, that guarantees high accuracy of the resulting scans by combining tachymeter-based tracking of the scanner, stereo, and structure-from-motion. This method provides scale information (by calibrated stereo), and does not require ground control points, because outside-in tracking avoids the typical issues of drift in structure-from-motion. The system is designed for flexibility, high throughput, approx. 0.1 mm precision, and an overall accuracy of the reconstructed 3D structure that conforms with the specifications of the tachymeter.

  11. 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.

  12. Locating very high energy gamma ray sources with arc minute accuracy

    NASA Technical Reports Server (NTRS)

    Akerlof, C. W.; Cawley, M. F.; Chantell, M.; Fegan, D. J.; Harris, K.; Hillas, A. M.; Jennings, D. G.; Lamb, R. C.; Lawrence, M. A.; Lang, M. J.

    1992-01-01

    The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of point-like sources were detected by the COS-B satellite, only two were unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of Very High Energy gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arc minute accuracy. This was demonstrated using Cerenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg.

  13. The research on the effect of atmospheric transmittance for the measuring accuracy of infrared thermal imager

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-cun; Chen, Yi-ming; Fu, Xian-bin; Luo, Cheng

    2016-07-01

    The effect of atmospheric transmittance on infrared thermal imager temperature measuring accuracy cannot be ignored when the object is far from infrared thermal imager. In this paper, a method of reducing the influence of atmospheric transmittance is proposed for the infrared thermal imager. Firstly, the temperature measuring formula of infrared thermal imager and the effect of atmospheric transmittance on temperature measuring accuracy is analyzed. According to the composition of the atmosphere, the main factors influencing the atmosphere transmittance are determined. Secondly, the temperature measuring model of infrared thermal imager in sea level is established according to the absorption of water vapor and carbon dioxide, the scattering of air molecules and aerosol particulate, and the attenuation effects of weather conditions such as rain and snow. Finally, the correctness and feasibility of the proposed model is verified by the comparison experiments of four different environmental conditions. According to the experiments, the temperature measuring accuracy of the infrared thermal imager is improved.

  14. A Method to Improve the Accuracy of Particle Diameter Measurements from Shadowgraph Images

    NASA Astrophysics Data System (ADS)

    Erinin, Martin A.; Wang, Dan; Liu, Xinan; Duncan, James H.

    2015-11-01

    A method to improve the accuracy of the measurement of the diameter of particles using shadowgraph images is discussed. To obtain data for analysis, a transparent glass calibration reticle, marked with black circular dots of known diameters, is imaged with a high-resolution digital camera using backlighting separately from both a collimated laser beam and diffuse white light. The diameter and intensity of each dot is measured by fitting an inverse hyperbolic tangent function to the particle image intensity map. Using these calibration measurements, a relationship between the apparent diameter and intensity of the dot and its actual diameter and position relative to the focal plane of the lens is determined. It is found that the intensity decreases and apparent diameter increases/decreases (for collimated/diffuse light) with increasing distance from the focal plane. Using the relationships between the measured properties of each dot and its actual size and position, an experimental calibration method has been developed to increase the particle-diameter-dependent range of distances from the focal plane for which accurate particle diameter measurements can be made. The support of the National Science Foundation under grant OCE0751853 from the Division of Ocean Sciences is gratefully acknowledged.

  15. Improvements in the accuracy and the repeatability of long trace profiler measurements

    SciTech Connect

    Takacs, P.Z.; Church, E.L.; Bresloff, C.J.; Assoufid, L.

    1999-09-01

    Modifications of the long trace profiler at the Advanced Photon Source at Argonne National Laboratory have significantly improved its accuracy and repeatability for measuring the figure of large flat and long-radius mirrors. Use of a Dove prism in the reference beam path corrects phasing problems between mechanical errors and thermally induced system errors. A single reference correction now completely removes both of these error signals from the measured surface profile. The addition of a precision air conditioner keeps the temperature in the metrology enclosure constant to within {plus_minus}0.1&hthinsp;{degree}C over a 24-h period and has significantly improved the stability and the repeatability of the measurements. Long-radius surface curvatures can now be measured absolutely with a high degree of confidence. These improved capabilities are illustrated with a series of measurements of a 500-mm-long mirror with a 5-km radius of curvature. The standard deviation in the average of ten slope profile scans is 0.3 {mu}rad, and the corresponding standard deviation in the height error is 4.6 nm. {copyright} 1999 Optical Society of America

  16. Improvements in the accuracy and the repeatability of long trace profiler measurements.

    PubMed

    Takacs, P Z; Church, E L; Bresloff, C J; Assoufid, L

    1999-09-01

    Modifications of the long trace profiler at the Advanced Photon Source at Argonne National Laboratory have significantly improved its accuracy and repeatability for measuring the figure of large flat and long-radius mirrors. Use of a Dove prism in the reference beam path corrects phasing problems between mechanical errors and thermally induced system errors. A single reference correction now completely removes both of these error signals from the measured surface profile. The addition of a precision air conditioner keeps the temperature in the metrology enclosure constant to within +/-0.1 degrees C over a 24-h period and has significantly improved the stability and the repeatability of the measurements. Long-radius surface curvatures can now be measured absolutely with a high degree of confidence. These improved capabilities are illustrated with a series of measurements of a 500-mm-long mirror with a 5-km radius of curvature. The standard deviation in the average of ten slope profile scans is 0.3 microrad, and the corresponding standard deviation in the height error is 4.6 nm. PMID:18324056

  17. Spatial, High-Accuracy, Positioning-Encoding Sensor (SHAPES) for large space system control applications

    NASA Technical Reports Server (NTRS)

    Mclauchlan, J. M.

    1982-01-01

    The Spatial, High-Accuracy, Position-Encoding Sensor is a controls sensor suitable for the determination of the static shape and vibrational motion of large space structures and similar systems and for the determination of position and velocity in rendezvous and docking. It uses a combination of electro-optical techniques to measure the three-dimensional coordinates distributed over the structure at reading rates high compared to the rates at which the coordinates are changing. The technical approach is that of measuring the distance to and the direction of points on the structure from a single sensor head. Many points can be measured simultaneously from a single head without significantly increasing the complexity of the system.

  18. Development of the One Centimeter Accuracy Geoid Model of Latvia for GNSS Measurements

    NASA Astrophysics Data System (ADS)

    Balodis, J.; Silabriedis, G.; Haritonova, D.; Kaļinka, M.; Janpaule, I.; Morozova, K.; Jumāre, I.; Mitrofanovs, I.; Zvirgzds, J.; Kaminskis, J.; Liepiņš, I.

    2015-11-01

    There is an urgent necessity for a highly accurate and reliable geoid model to enable prompt determination of normal height with the use of GNSS coordinate determination due to the high precision requirements in geodesy, building and high precision road construction development. Additionally, the Latvian height system is in the process of transition from BAS- 77 (Baltic Height System) to EVRS2007 system. The accuracy of the geoid model must approach the precision of about ∼1 cm looking forward to the Baltic Rail and other big projects. The use of all the available and verified data sources is planned, including the use of enlarged set of GNSS/levelling data, gravimetric measurement data and, additionally, the vertical deflection measurements over the territory of Latvia. The work is going ahead stepwise. Just the issue of GNSS reference network stability is discussed. In order to achieve the ∼1 cm precision geoid, it is required to have a homogeneous high precision GNSS network as a basis for ellipsoidal height determination for GNSS/levelling points. Both the LatPos and EUPOS® - Riga network have been examined in this article.

  19. Accuracy and precision of quantitative 31P-MRS measurements of human skeletal muscle mitochondrial function.

    PubMed

    Layec, Gwenael; Gifford, Jayson R; Trinity, Joel D; Hart, Corey R; Garten, Ryan S; Park, Song Y; Le Fur, Yann; Jeong, Eun-Kee; Richardson, Russell S

    2016-08-01

    Although theoretically sound, the accuracy and precision of (31)P-magnetic resonance spectroscopy ((31)P-MRS) approaches to quantitatively estimate mitochondrial capacity are not well documented. Therefore, employing four differing models of respiratory control [linear, kinetic, and multipoint adenosine diphosphate (ADP) and phosphorylation potential], this study sought to determine the accuracy and precision of (31)P-MRS assessments of peak mitochondrial adenosine-triphosphate (ATP) synthesis rate utilizing directly measured peak respiration (State 3) in permeabilized skeletal muscle fibers. In 23 subjects of different fitness levels, (31)P-MRS during a 24-s maximal isometric knee extension and high-resolution respirometry in muscle fibers from the vastus lateralis was performed. Although significantly correlated with State 3 respiration (r = 0.72), both the linear (45 ± 13 mM/min) and phosphorylation potential (47 ± 16 mM/min) models grossly overestimated the calculated in vitro peak ATP synthesis rate (P < 0.05). Of the ADP models, the kinetic model was well correlated with State 3 respiration (r = 0.72, P < 0.05), but moderately overestimated ATP synthesis rate (P < 0.05), while the multipoint model, although being somewhat less well correlated with State 3 respiration (r = 0.55, P < 0.05), most accurately reflected peak ATP synthesis rate. Of note, the PCr recovery time constant (τ), a qualitative index of mitochondrial capacity, exhibited the strongest correlation with State 3 respiration (r = 0.80, P < 0.05). Therefore, this study reveals that each of the (31)P-MRS data analyses, including PCr τ, exhibit precision in terms of mitochondrial capacity. As only the multipoint ADP model did not overstimate the peak skeletal muscle mitochondrial ATP synthesis, the multipoint ADP model is the only quantitative approach to exhibit both accuracy and precision. PMID:27302751

  20. Effect of refraction parallax on the accuracy of measuring the angular coordinates of artificial satellites

    NASA Astrophysics Data System (ADS)

    Vygon, V. G.; Deryugina, A. I.

    1994-03-01

    This paper analyzes the effect of optical refraction in the earth's atmosphere on the accuracy of astronometric measurements, and presents the results of calculations that were used to investigate the accuracy with which the orbits of artificial satellites are reconstructed from the data of goniometric observations. It is shown that, in a number of cases, neglecting the effect of refraction parallax results in fundamental errors in the character of the reconstructed trajectories.

  1. The Implications for Higher-Accuracy Absolute Measurements for NGS and its GRAV-D Project

    NASA Astrophysics Data System (ADS)

    Childers, V. A.; Winester, D.; Roman, D. R.; Eckl, M. C.; Smith, D. A.

    2013-12-01

    Absolute and relative gravity measurements play an important role in the work of NOAA's National Geodetic Survey (NGS). When NGS decided to replace the US national vertical datum, the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project added a new dimension to the NGS gravity program. Airborne gravity collection would complement existing satellite and surface gravity data to allow the creation of a gravimetric geoid sufficiently accurate to form the basis of the new reference surface. To provide absolute gravity ties for the airborne surveys, initially new FG5 absolute measurements were made at existing absolute stations and relative measurements were used to transfer those measurements to excenters near the absolute mark and to the aircraft sensor height at the parking space. In 2011, NGS obtained a field-capable A10 absolute gravimeter from Micro-g LaCoste which became the basis of the support of the airborne surveys. Now A10 measurements are made at the aircraft location and transferred to sensor height. Absolute and relative gravity play other roles in GRAV-D. Comparison of surface data with new airborne collection will highlight surface surveys with bias or tilt errors and can provide enough information to repair or discard the data. We expect that areas of problem surface data may be re-measured. The GRAV-D project also plans to monitor the geoid in regions of rapid change and update the vertical datum when appropriate. Geoid change can result from glacial isostatic adjustment (GIA), tectonic change, and the massive drawdown of large scale aquifers. The NGS plan for monitoring these changes over time is still in its preliminary stages and is expected to rely primarily on the GRACE and GRACE Follow On satellite data in conjunction with models of GIA and tectonic change. We expect to make absolute measurements in areas of rapid change in order to verify model predictions. With the opportunities presented by rapid, highly accurate

  2. [Study on high accuracy detection of multi-component gas in oil-immerse power transformer].

    PubMed

    Fan, Jie; Chen, Xiao; Huang, Qi-Feng; Zhou, Yu; Chen, Gang

    2013-12-01

    In order to solve the problem of low accuracy and mutual interference in multi-component gas detection, a kind of multi-component gas detection network with high accuracy was designed. A semiconductor laser with narrow bandwidth was utilized as light source and a novel long-path gas cell was also used in this system. By taking the single sine signal to modulate the spectrum of laser and using space division multiplexing (SDM) and time division multiplexing (TDM) technique, the detection of multi-component gas was achieved. The experiments indicate that the linearity relevance coefficient is 0. 99 and the measurement relative error is less than 4%. The system dynamic response time is less than 15 s, by filling a volume of multi-component gas into the gas cell gradually. The system has advantages of high accuracy and quick response, which can be used in the fault gas on-line monitoring for power transformers in real time. PMID:24611396

  3. Dynamic Modeling Accuracy Dependence on Errors in Sensor Measurements, Mass Properties, and Aircraft Geometry

    NASA Technical Reports Server (NTRS)

    Grauer, Jared A.; Morelli, Eugene A.

    2013-01-01

    A nonlinear simulation of the NASA Generic Transport Model was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of dynamic models identified from flight data. Measurements from a typical system identification maneuver were systematically and progressively deteriorated and then used to estimate stability and control derivatives within a Monte Carlo analysis. Based on the results, recommendations were provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using other flight conditions, parameter estimation methods, and a full-scale F-16 nonlinear aircraft simulation were compared with these recommendations.

  4. Determination of the conversion gain and the accuracy of its measurement for detector elements and arrays

    NASA Astrophysics Data System (ADS)

    Beecken, B. P.; Fossum, E. R.

    1996-07-01

    Standard statistical theory is used to calculate how the accuracy of a conversion-gain measurement depends on the number of samples. During the development of a theoretical basis for this calculation, a model is developed that predicts how the noise levels from different elements of an ideal detector array are distributed. The model can also be used to determine what dependence the accuracy of measured noise has on the size of the sample. These features have been confirmed by experiment, thus enhancing the credibility of the method for calculating the uncertainty of a measured conversion gain. detector-array uniformity, charge coupled device, active pixel sensor.

  5. New High-Accuracy Methods for Automatically Detecting & Tracking CMEs

    NASA Astrophysics Data System (ADS)

    Byrne, Jason; Morgan, H.; Habbal, S. R.

    2012-05-01

    With the large amounts of CME image data available from the SOHO and STEREO coronagraphs, manual cataloguing of events can be tedious and subject to user bias. Therefore automated catalogues, such as CACTus and SEEDS, have been developed in an effort to produce a robust method of detection and analysis of events. Here we present the development of a new CORIMP (coronal image processing) CME detection and tracking technique that overcomes many of the drawbacks of previous methods. It works by first employing a dynamic CME separation technique to remove the static background, and then characterizing CMEs via a multiscale edge-detection algorithm. This allows the inherent structure of the CMEs to be revealed in each image, which is usually prone to spatiotemporal crosstalk as a result of traditional image-differencing techniques. Thus the kinematic and morphological information on each event is resolved with higher accuracy than previous catalogues, revealing CME acceleration and expansion profiles otherwise undetected, and enabling a determination of the varying speeds attained across the span of the CME. The potential for a 3D characterization of the internal structure of CMEs is also demonstrated.

  6. A hyperspectral imager for high radiometric accuracy Earth climate studies

    NASA Astrophysics Data System (ADS)

    Espejo, Joey; Drake, Ginger; Heuerman, Karl; Kopp, Greg; Lieber, Alex; Smith, Paul; Vermeer, Bill

    2011-10-01

    We demonstrate a visible and near-infrared prototype pushbroom hyperspectral imager for Earth climate studies that is capable of using direct solar viewing for on-orbit cross calibration and degradation tracking. Direct calibration to solar spectral irradiances allow the Earth-viewing instrument to achieve required climate-driven absolute radiometric accuracies of <0.2% (1σ). A solar calibration requires viewing scenes having radiances 105 higher than typical Earth scenes. To facilitate this calibration, the instrument features an attenuation system that uses an optimized combination of different precision aperture sizes, neutral density filters, and variable integration timing for Earth and solar viewing. The optical system consists of a three-mirror anastigmat telescope and an Offner spectrometer. The as-built system has a 12.2° cross track field of view with 3 arcmin spatial resolution and covers a 350-1050 nm spectral range with 10 nm resolution. A polarization compensated configuration using the Offner in an out of plane alignment is demonstrated as a viable approach to minimizing polarization sensitivity. The mechanical design takes advantage of relaxed tolerances in the optical design by using rigid, non-adjustable diamond-turned tabs for optical mount locating surfaces. We show that this approach achieves the required optical performance. A prototype spaceflight unit is also demonstrated to prove the applicability of these solar cross calibration methods to on-orbit environments. This unit is evaluated for optical performance prior to and after GEVS shake, thermal vacuum, and lifecycle tests.

  7. An angle encoder for super-high resolution and super-high accuracy using SelfA

    NASA Astrophysics Data System (ADS)

    Watanabe, Tsukasa; Kon, Masahito; Nabeshima, Nobuo; Taniguchi, Kayoko

    2014-06-01

    Angular measurement technology at high resolution for applications such as in hard disk drive manufacturing machines, precision measurement equipment and aspherical process machines requires a rotary encoder with high accuracy, high resolution and high response speed. However, a rotary encoder has angular deviation factors during operation due to scale error or installation error. It has been assumed to be impossible to achieve accuracy below 0.1″ in angular measurement or control after the installation onto the rotating axis. Self-calibration (Lu and Trumper 2007 CIRP Ann. 56 499; Kim et al 2011 Proc. MacroScale; Probst 2008 Meas. Sci. Technol. 19 015101; Probst et al Meas. Sci. Technol. 9 1059; Tadashi and Makoto 1993 J. Robot. Mechatronics 5 448; Ralf et al 2006 Meas. Sci. Technol. 17 2811) and cross-calibration (Probst et al 1998 Meas. Sci. Technol. 9 1059; Just et al 2009 Precis. Eng. 33 530; Burnashev 2013 Quantum Electron. 43 130) technologies for a rotary encoder have been actively discussed on the basis of the principle of circular closure. This discussion prompted the development of rotary tables which achieve reliable and high accuracy angular verification. We apply these technologies for the development of a rotary encoder not only to meet the requirement of super-high accuracy but also to meet that of super-high resolution. This paper presents the development of an encoder with 221 = 2097 152 resolutions per rotation (360°), that is, corresponding to a 0.62″ signal period, achieved by the combination of a laser rotary encoder supplied by Magnescale Co., Ltd and a self-calibratable encoder (SelfA) supplied by The National Institute of Advanced Industrial Science & Technology (AIST). In addition, this paper introduces the development of a rotary encoder to guarantee ±0.03″ accuracy at any point of the interpolated signal, with respect to the encoder at the minimum resolution of 233, that is, corresponding to a 0.0015″ signal period after

  8. Accuracy and precision of cone beam computed tomography in periodontal defects measurement (systematic review).

    PubMed

    Anter, Enas; Zayet, Mohammed Khalifa; El-Dessouky, Sahar Hosny

    2016-01-01

    Systematic review of literature was made to assess the extent of accuracy of cone beam computed tomography (CBCT) as a tool for measurement of alveolar bone loss in periodontal defect. A systematic search of PubMed electronic database and a hand search of open access journals (from 2000 to 2015) yielded abstracts that were potentially relevant. The original articles were then retrieved and their references were hand searched for possible missing articles. Only articles that met the selection criteria were included and criticized. The initial screening revealed 47 potentially relevant articles, of which only 14 have met the selection criteria; their CBCT average measurements error ranged from 0.19 mm to 1.27 mm; however, no valid meta-analysis could be made due to the high heterogeneity between the included studies. Under the limitation of the number and strength of the available studies, we concluded that CBCT provides an assessment of alveolar bone loss in periodontal defect with a minimum reported mean measurements error of 0.19 ± 0.11 mm and a maximum reported mean measurements error of 1.27 ± 1.43 mm, and there is no agreement between the studies regarding the direction of the deviation whether over or underestimation. However, we should emphasize that the evidence to this data is not strong. PMID:27563194

  9. Accuracy and precision of cone beam computed tomography in periodontal defects measurement (systematic review)

    PubMed Central

    Anter, Enas; Zayet, Mohammed Khalifa; El-Dessouky, Sahar Hosny

    2016-01-01

    Systematic review of literature was made to assess the extent of accuracy of cone beam computed tomography (CBCT) as a tool for measurement of alveolar bone loss in periodontal defect. A systematic search of PubMed electronic database and a hand search of open access journals (from 2000 to 2015) yielded abstracts that were potentially relevant. The original articles were then retrieved and their references were hand searched for possible missing articles. Only articles that met the selection criteria were included and criticized. The initial screening revealed 47 potentially relevant articles, of which only 14 have met the selection criteria; their CBCT average measurements error ranged from 0.19 mm to 1.27 mm; however, no valid meta-analysis could be made due to the high heterogeneity between the included studies. Under the limitation of the number and strength of the available studies, we concluded that CBCT provides an assessment of alveolar bone loss in periodontal defect with a minimum reported mean measurements error of 0.19 ± 0.11 mm and a maximum reported mean measurements error of 1.27 ± 1.43 mm, and there is no agreement between the studies regarding the direction of the deviation whether over or underestimation. However, we should emphasize that the evidence to this data is not strong. PMID:27563194

  10. An Accuracy--Response Time Capacity Assessment Function that Measures Performance against Standard Parallel Predictions

    ERIC Educational Resources Information Center

    Townsend, James T.; Altieri, Nicholas

    2012-01-01

    Measures of human efficiency under increases in mental workload or attentional limitations are vital in studying human perception, cognition, and action. Assays of efficiency as workload changes have typically been confined to either reaction times (RTs) or accuracy alone. Within the realm of RTs, a nonparametric measure called the "workload…

  11. Evaluation of Measurement Accuracy in Neutron and X-ray Radiography

    NASA Astrophysics Data System (ADS)

    Rogers, John; Amaral-Rogers, Alex; Christodoulou, Marios

    This paper aims at reviewing analysis procedures on digital radiographic images and the corrections that have to be included to obtain the highest measurement accuracy. It will refer to dimensional measurements in determining particle movements in fluid flow and in comparisons of dimensional changes or movements in operating machinery or test objects.

  12. Assessing the Accuracy and Consistency of Language Proficiency Classification under Competing Measurement Models

    ERIC Educational Resources Information Center

    Zhang, Bo

    2010-01-01

    This article investigates how measurement models and statistical procedures can be applied to estimate the accuracy of proficiency classification in language testing. The paper starts with a concise introduction of four measurement models: the classical test theory (CTT) model, the dichotomous item response theory (IRT) model, the testlet response…

  13. Limb volume measurements: comparison of accuracy and decisive parameters of the most used present methods.

    PubMed

    Chromy, Adam; Zalud, Ludek; Dobsak, Petr; Suskevic, Igor; Mrkvicova, Veronika

    2015-01-01

    Limb volume measurements are used for evaluating growth of muscle mass and effectivity of strength training. Beside sport sciences, it is used e.g. for detection of oedemas, lymphedemas or carcinomas or for examinations of muscle atrophy. There are several commonly used methods, but there is a lack of clear comparison, which shows their advantages and limits. The accuracy of each method is uncertainly estimated only. The aim of this paper is to determine and experimentally verify their accuracy and compare them among each other. Water Displacement Method (WD), three methods based on circumferential measures-Frustum Sign Model (FSM), Disc Model (DM), Partial Frustum Model (PFM) and two 3D scan based methods Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) were compared. Precise reference cylinders and limbs of two human subjects were measured 10 times by each method. Personal dependency of methods was also tested by measuring 10 times the same object by 3 different people. Accuracies: WD 0.3 %, FSM 2-8 % according person, DM, PFM 1-8 %, MRI 2 % (hand) or 8 % (finger), CT 0.5 % (hand) or 2 % (finger);times: FSM 1 min, CT 7 min, WD, DM, PFM 15 min, MRI 19 min; and more. WD was found as the best method for most of uses with best accuracy. The CT disposes with almost the same accuracy and allows measurements of specific regions (e.g. particular muscles), as same as MRI, which accuracy is worse though, but it is not harmful. Frustum Sign Model is usable for very fast estimation of limb volume, but with lower accuracy, Disc Model and Partial Frustum Model is useful in cases when Water Displacement cannot be used. PMID:26618096

  14. High accuracy hole filling for Kinect depth maps

    NASA Astrophysics Data System (ADS)

    Wang, Jianxin; An, Ping; Zuo, Yifan; You, Zhixiang; Zhang, Zhaoyang

    2014-10-01

    Hole filling of depth maps is a core technology of the Kinect based visual system. In this paper, we propose a hole filling algorithm for Kinect depth maps based on separately repairing of the foreground and background. There are two-part processing in the proposed algorithm. Firstly, a fast pre-processing to the Kinect depth map holes is performed. In this part, we fill the background holes of Kinect depth maps with the deepest depth image which is constructed by combining the spatio-temporal information of the pixels in Kinect depth map with the corresponding color information in the Kinect color image. The second step is the enhancement for the pre-processing depth maps. We propose a depth enhancement algorithm based on the joint information of geometry and color. Since the geometry information is more robust than the color, we correct the depth by affine transform in prior to utilizing the color cues. Then we determine the filter parameters adaptively based on the local features of the color image which solves the texture copy problem and protects the fine structures. Since L1 norm optimization is more robust to data outliers than L2 norm optimization, we force the filtered value to be the solution for L1 norm optimization. Experimental results show that the proposed algorithm can protect the intact foreground depth, improve the accuracy of depth at object edges, and eliminate the flashing phenomenon of depth at objects edges. In addition, the proposed algorithm can effectively fill the big depth map holes generated by optical reflection.

  15. Measurement and accuracy analysis of refractive index using a specular reflectivity close to the total internal reflection

    NASA Astrophysics Data System (ADS)

    Li, Hui; Lu, Zukang; Xie, Shusen; Lin, Lei

    1998-08-01

    A new method to measure refractive index and the accuracy analysis as well is presented. The characteristic includes that the direction of incident light is not perpendicular to the interface but close to the critical angle of total internal reflection. That the specular reflectivity changes sharply near the critical angle implies that a high measuring sensitivity be reached easily. A narrow p- polarized laser beam and a prism or a quasi-semi-cylindrical lens in contact with a sample are applied in the apparatus. In order to match a high accuracy, a photoelectronic receiver with dual-channel divider is designed to compensate the stability of output of laser. One of the advantages of the method is its high accuracy. The uncertainty in the refractive index measurement is in the fourth decimal place at least. The exact direction of incident laser beam depends on the accuracy of result expected. Another outstanding advantage is its particularly straightforward in use experimental techniques. The method will be the most promising tool to study the response of refractive index to subtle changes of different conditions.

  16. High Accuracy Beam Current Monitor System for CEBAF'S Experimental Hall A

    SciTech Connect

    J. Denard; A. Saha; G. Lavessiere

    2001-07-01

    CEBAF accelerator delivers continuous wave (CW) electron beams to three experimental Halls. In Hall A, all experiments require continuous, non-invasive current measurements and a few experiments require an absolute accuracy of 0.2 % in the current range from 1 to 180 {micro}A. A Parametric Current Transformer (PCT), manufactured by Bergoz, has an accurate and stable sensitivity of 4 {micro}A/V but its offset drifts at the muA level over time preclude its direct use for continuous measurements. Two cavity monitors are calibrated against the PCT with at least 50 {micro}A of beam current. The calibration procedure suppresses the error due to PCT's offset drifts by turning the beam on and off, which is invasive to the experiment. One of the goals of the system is to minimize the calibration time without compromising the measurement's accuracy. The linearity of the cavity monitors is a critical parameter for transferring the accurate calibration done at high currents over the whole dynamic range. The method for measuring accurately the linearity is described.

  17. The measurement of pointing accuracy of two-dimensional scan mirror

    NASA Astrophysics Data System (ADS)

    Xing, Hui; An, Chao; Song, Junru; He, Xuhua

    2015-10-01

    The observation accuracy of space camera targeted on ground objects is directly affected by the pointing deviation of the two dimensional scan mirror. A plane model of the scan mirror's normal trajectory is established when scan mirror is rotating along the rolling axis while the pitching axis remains still. The pointing accuracy of scan mirror cross the track direction is measured with the plane model. A cone model of the scan mirror's normal trajectory is established when scan mirror is rotating along the pitching axis while the rolling axis remains still. The pointing accuracy of scan mirror along the track direction is measured with the plane model. The nonorthogonality of shafting of the rolling axis and the pitching axis is measured with the two models. Data processing results are feedback to pointing controller to correct the input signal of resolver, until the pointing accuracy of scan mirror meets the requirement. The experimental results indicate that the models of measuring the pointing accuracy of scan mirror are accurate and the data processing algorithm is feasible. The testing precision reached 10-3 second.

  18. Accuracy in blood glucose measurement: what will a tightening of requirements yield?

    PubMed

    Heinemann, Lutz; Lodwig, Volker; Freckmann, Guido

    2012-03-01

    Nowadays, almost all persons with diabetes--at least those using antidiabetic drug therapy--use one of a plethora of meters commercially available for self-monitoring of blood glucose. The accuracy of blood glucose (BG) measurement using these meters has been presumed to be adequate; that is, the accuracy of these devices was not usually questioned until recently. Health authorities in the United States (Food and Drug Administration) and in other countries are currently endeavoring to tighten the requirements for the accuracy of these meters above the level that is currently stated in the standard ISO 15197. At first glance, this does not appear to be a problem and is hardly worth further consideration, but a closer look reveals a considerable range of critical aspects that will be discussed in this commentary. In summary, one could say that as a result of modern production methods and ongoing technical advances, the demands placed on the quality of measurement results obtained with BG meters can be increased to a certain degree. One should also take into consideration that the system accuracy (which covers many more aspects as the analytical accuracy) required to make correct therapeutical decisions certainly varies for different types of therapy. At the end, in addition to analytical accuracy, thorough and systematic training of patients and regular refresher training is important to minimize errors. Only under such circumstances will patients make appropriate therapeutic interventions to optimize and maintain metabolic control. PMID:22538158

  19. Accuracy and repeatability of Roentgen stereophotogrammetric analysis (RSA) for measuring knee laxity in longitudinal studies.

    PubMed

    Fleming, B C; Peura, G D; Abate, J A; Beynnon, B D

    2001-10-01

    Roentgen stereophotogrammetric analysis (RSA) can be used to assess temporal changes in anterior-posterior (A-P) knee laxity. However, the accuracy and precision of RSA is dependent on many factors and should be independently evaluated for a particular application. The objective of this study was to evaluate the use of RSA for measuring A-P knee laxity. The specific aims were to assess the variation or "noise" inherent to RSA, to determine the reproducibility of RSA for repeated A-P laxity testing, and to assess the accuracy of these measurements. Two experiments were performed. The first experiment utilized three rigid models of the tibiofemoral joint to assess the noise and to compare digitization errors of two independent examiners. No differences were found in the kinematic outputs of the RSA due to examiner, repeated trials, or the model used. In a second experiment, A-P laxity values between the A-P shear load limits of +/-60 N of five cadaver goat knees were measured to assess the error associated with repeated testing. The RSA laxity values were also compared to those obtained from a custom designed linkage system. The mean A-P laxity values with the knee 30 degrees, 60 degrees, and 90 degrees of flexion for the ACL-intact goat knee (+/-95% confidence interval) were 0.8 (+/-0.25), 0.9 (+/-0.29), and 0.4 (+/-0.22) mm, respectively. In the ACL-deficient knee, the A-P laxity values increased by an order of magnitude to 8.8 (+/-1.39), 7.6 (+/-1.32), and 3.1 (+/-1.20)mm, respectively. No significant differences were found between the A-P laxity values measured by RSA and the independent measurement technique. A highly significant linear relationship (r(2)=0.83) was also found between these techniques. This study suggests that the RSA method is an accurate and precise means to measure A-P knee laxity for repeated testing over time. PMID:11522316

  20. Higher Accuracy Measurements of Photochemical Properties of Very Short-Lived Substances.

    NASA Astrophysics Data System (ADS)

    Orkin, V. L.; Khamaganov, V. G.; Kurylo, M. J., III

    2015-12-01

    atmospheric modeling. High accuracy IR and UV absorption spectra were measured to allow the estimation of GWP and ODPs of candidate replacement compounds and their detection in the atmosphere.

  1. Placement of the material temperature sensor during measuring the accuracy of CNC machine tools

    NASA Astrophysics Data System (ADS)

    Zhao, Dong-sheng; Jia, Min-qiang; Zhang, Jian; Sun, Lei; Li, Wei-jun

    2013-10-01

    In view of the dispute on the placement of material sensor when measuring the positional accuracy of a linear axis of a CNC machine tool, this paper presents the method and principle of deciding where to put the material temperature sensor. The positional accuracy of the linear axis of the machine tool is one of the most important performance parameters, and it must be measured when setup and check. The placement of the material temperature sensor has great influence on the measurement accuracy. At present, there are two main views on this issue: one is to place the sensor on the table of the machine tool, the other is to place it on the feedback system. This conflict between these two debates often makes the measurers feel confused and as a result influences the measure quality, sometimes. This thesis attempts to classify the CNC machine tools positional accuracy measurement according to its different purposes, then further presents the best placement. The thesis also elaborates other relevant questions of the placement of the material temperature sensor.

  2. Accuracy improvement in laser stripe extraction for large-scale triangulation scanning measurement system

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Liu, Wei; Li, Xiaodong; Yang, Fan; Gao, Peng; Jia, Zhenyuan

    2015-10-01

    Large-scale triangulation scanning measurement systems are widely used to measure the three-dimensional profile of large-scale components and parts. The accuracy and speed of the laser stripe center extraction are essential for guaranteeing the accuracy and efficiency of the measuring system. However, in the process of large-scale measurement, multiple factors can cause deviation of the laser stripe center, including the spatial light intensity distribution, material reflectivity characteristics, and spatial transmission characteristics. A center extraction method is proposed for improving the accuracy of the laser stripe center extraction based on image evaluation of Gaussian fitting structural similarity and analysis of the multiple source factors. First, according to the features of the gray distribution of the laser stripe, evaluation of the Gaussian fitting structural similarity is estimated to provide a threshold value for center compensation. Then using the relationships between the gray distribution of the laser stripe and the multiple source factors, a compensation method of center extraction is presented. Finally, measurement experiments for a large-scale aviation composite component are carried out. The experimental results for this specific implementation verify the feasibility of the proposed center extraction method and the improved accuracy for large-scale triangulation scanning measurements.

  3. Towards High Accuracy Reflectometry for Extreme-Ultraviolet Lithography

    PubMed Central

    Tarrio, Charles; Grantham, Steven; Squires, Matthew B.; Vest, Robert E.; Lucatorto, Thomas B.

    2003-01-01

    Currently the most demanding application of extreme ultraviolet optics is connected with the development of extreme ultraviolet lithography. Not only does each of the Mo/Si multilayer extreme-ultraviolet stepper mirrors require the highest attainable reflectivity at 13 nm (nearly 70 %), but the central wavelength of the reflectivity of these mirrors must be measured with a wavelength repeatability of 0.001 nm and the peak reflectivity of the reflective masks with a repeatability of 0.12 %. We report on two upgrades of our NIST/DARPA Reflectometry Facility that have given us the ability to achieve 0.1 % repeatability and 0.3 % absolute uncertainty in our reflectivity measurements. A third upgrade, a monochromator with thermal and mechanical stability for improved wavelength repeatability, is currently in the design phase.

  4. High accuracy particle analysis using sheathless microfluidic impedance cytometry.

    PubMed

    Spencer, Daniel; Caselli, Federica; Bisegna, Paolo; Morgan, Hywel

    2016-07-01

    This paper describes a new design of microfluidic impedance cytometer enabling accurate characterization of particles without the need for focusing. The approach uses multiple pairs of electrodes to measure the transit time of particles through the device in two simultaneous different current measurements, a transverse (top to bottom) current and an oblique current. This gives a new metric that can be used to estimate the vertical position of the particle trajectory through the microchannel. This parameter effectively compensates for the non-uniform electric field in the channel that is an unavoidable consequence of the use of planar parallel facing electrodes. The new technique is explained and validated using numerical modelling. Impedance data for 5, 6 and 7 μm particles are collected and compared with simulations. The method gives excellent coefficient of variation in (electrical) radius of particles of 1% for a sheathless configuration. PMID:27241585

  5. High-accuracy Subdaily ERPs from the IGS

    NASA Astrophysics Data System (ADS)

    Ray, J. R.; Griffiths, J.

    2012-04-01

    Since November 2000 the International GNSS Service (IGS) has published Ultra-rapid (IGU) products for near real-time (RT) and true real-time applications. They include satellite orbits and clocks, as well as Earth rotation parameters (ERPs) for a sliding 48-hr period. The first day of each update is based on the most recent GPS and GLONASS observational data from the IGS hourly tracking network. At the time of release, these observed products have an initial latency of 3 hr. The second day of each update consists of predictions. So the predictions between about 3 and 9 hr into the second half are relevant for true RT uses. Originally updated twice daily, the IGU products since April 2004 have been issued every 6 hr, at 3, 9, 15, and 21 UTC. Up to seven Analysis Centers (ACs) contribute to the IGU combinations. Two sets of ERPs are published with each IGU update, observed values at the middle epoch of the first half and predicted values at the middle epoch of the second half. The latency of the near RT ERPs is 15 hr while the predicted ERPs, based on projections of each AC's most recent determinations, are issued 9 hr ahead of their reference epoch. While IGU ERPs are issued every 6 hr, each set represents an integrated estimate over the surrounding 24 hr. So successive values are temporally correlated with about 75% of the data being common; this fact should be taken into account in user assimilations. To evaluate the accuracy of these near RT and predicted ERPs, they have been compared to the IGS Final ERPs, available about 11 to 17 d after data collection. The IGU products improved dramatically in the earlier years but since about 2008.0 the performance has been stable and excellent. During the last three years, RMS differences for the observed IGU ERPs have been about 0.036 mas and 0.0101 ms for each polar motion component and LOD respectively. (The internal precision of the reference IGS ERPs over the same period is about 0.016 mas for polar motion and 0

  6. The Effect of By-pass Current on the Accuracy of Resistivity Measurement in a Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Peng, Gang; Liu, Cai-Long; Lu, Han; Han, Yong-Hao; Gao, Chun-Xiao

    2013-06-01

    We report a quantitative analysis of by-pass current effect on the accuracy of resistivity measurement in a diamond anvil cell. Due to the by-pass current, the sample resistivity calculated by the van der Pauw method is obviously smaller than the actual value and the problem becomes more serious for a high-resistivity sample. For the consideration of high accuracy of resistivity measurement, a method is presented that the inside wall of the sample chamber should be covered by a polymethylmethane layer. With this highly insulating layer, the by-pass current is effectively prevented and the current density distribution inside the sample is very close to the ideal case.

  7. Development of high accuracy and resolution geoid and gravity maps

    NASA Technical Reports Server (NTRS)

    Gaposchkin, E. M.

    1986-01-01

    Precision satellite to satellite tracking can be used to obtain high precision and resolution maps of the geoid. A method is demonstrated to use data in a limited region to map the geopotential at the satellite altitude. An inverse method is used to downward continue the potential to the Earth surface. The method is designed for both satellites in the same low orbit.

  8. 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.

  9. Influence of object-system distance on accuracy of remote temperature measurement with IR systems

    NASA Astrophysics Data System (ADS)

    Chrzanowski, K.

    1995-04-01

    An investigation on the effect of the differencebetween the values of the distance object-system under calibration and real work conditions on the accuracy of the temperature measurement with IR systems has been carried out. The formulas that enable determination of the temperature measurement errors due to this difference for any measurement conditions and system parameters has been developed. It has been shown that the errors due to this source can be significant.

  10. High-Accuracy Ring Laser Gyroscopes: Earth Rotation Rate and Relativistic Effects

    NASA Astrophysics Data System (ADS)

    Beverini, N.; Di Virgilio, A.; Belfi, J.; Ortolan, A.; Schreiber, K. U.; Gebauer, A.; Klügel, T.

    2016-06-01

    The Gross Ring G is a square ring laser gyroscope, built as a monolithic Zerodur structure with 4 m length on all sides. It has demonstrated that a large ring laser provides a sensitivity high enough to measure the rotational rate of the Earth with a high precision of ΔΩE < 10-8. It is possible to show that further improvement in accuracy could allow the observation of the metric frame dragging, produced by the Earth rotating mass (Lense-Thirring effect), as predicted by General Relativity. Furthermore, it can provide a local measurement of the Earth rotational rate with a sensitivity near to that provided by the international system IERS. The GINGER project is intending to take this level of sensitivity further and to improve the accuracy and the long-term stability. A monolithic structure similar to the G ring laser is not available for GINGER. Therefore the preliminary goal is the demonstration of the feasibility of a larger gyroscope structure, where the mechanical stability is obtained through an active control of the geometry. A prototype moderate size gyroscope (GP-2) has been set up in Pisa in order to test this active control of the ring geometry, while a second structure (GINGERino) has been installed inside the Gran Sasso underground laboratory in order to investigate the properties of a deep underground laboratory in view of an installation of a future GINGER apparatus. The preliminary data on these two latter instruments are presented.

  11. High-accuracy registration of intraoperative CT imaging

    NASA Astrophysics Data System (ADS)

    Oentoro, A.; Ellis, R. E.

    2010-02-01

    Image-guided interventions using intraoperative 3D imaging can be less cumbersome than systems dependent on preoperative images, especially by needing neither potentially invasive image-to-patient registration nor a lengthy process of segmenting and generating a 3D surface model. In this study, a method for computer-assisted surgery using direct navigation on intraoperative imaging is presented. In this system the registration step of a navigated procedure was divided into two stages: preoperative calibration of images to a ceiling-mounted optical tracking system, and intraoperative tracking during acquisition of the 3D medical image volume. The preoperative stage used a custom-made multi-modal calibrator that could be optically tracked and also contained fiducial spheres for radiological detection; a robust registration algorithm was used to compensate for the very high false-detection rate that was due to the high physical density of the optical light-emitting diodes. Intraoperatively, a tracking device was attached to plastic bone models that were also instrumented with radio-opaque spheres; A calibrated pointer was used to contact the latter spheres as a validation of the registration. Experiments showed that the fiducial registration error of the preoperative calibration stage was approximately 0.1 mm. The target registration error in the validation stage was approximately 1.2 mm. This study suggests that direct registration, coupled with procedure-specific graphical rendering, is potentially a highly accurate means of performing image-guided interventions in a fast, simple manner.

  12. Assessing the Accuracy of Sentinel-3 SLSTR Sea-Surface Temperature Retrievals Using High Accuracy Infrared Radiiometers on Ships of Opportunity

    NASA Astrophysics Data System (ADS)

    Minnett, P. J.; Izaguirre, M. A.; Szcszodrak, M.; Williams, E.; Reynolds, R. M.

    2015-12-01

    The assessment of errors and uncertainties in satellite-derived SSTs can be achieved by comparisons with independent measurements of skin SST of high accuracy. Such validation measurements are provided by well-calibrated infrared radiometers mounted on ships. The second generation of Marine-Atmospheric Emitted Radiance Interferometers (M-AERIs) have recently been developed and two are now deployed on cruise ships of Royal Caribbean Cruise Lines that operate in the Caribbean Sea, North Atlantic and Mediterranean Sea. In addition, two Infrared SST Autonomous Radiometers (ISARs) are mounted alternately on a vehicle transporter of NYK Lines that crosses the Pacific Ocean between Japan and the USA. Both M-AERIs and ISARs are self-calibrating radiometers having two internal blackbody cavities to provide at-sea calibration of the measured radiances, and the accuracy of the internal calibration is periodically determined by measurements of a NIST-traceable blackbody cavity in the laboratory. This provides SI-traceability for the at-sea measurements. It is anticipated that these sensors will be deployed during the next several years and will be available for the validation of the SLSTRs on Sentinel-3a and -3b.

  13. Maximum measurement range and accuracy of SAW reflective delay line sensors.

    PubMed

    Zheng, Zehua; Han, Tao; Qin, Peng

    2015-01-01

    In a surface acoustic wave (SAW) wireless sensor with a reflective delay line structure, three reflectors are often used to eliminate 2π ambiguity of phase measurement. The maximum range of the measured parameter and the maximum accuracy have recently been attracting much research attention. In this paper, an analytical formula for all the factors influencing the measurement range and accuracy of the delay line SAW sensor are deduced for the first time. The factors include: the sensor sensitivity, the topology of the delay line, the available wireless bandwidth and the allowed maximum phase measuring error of the reading system, which is easier to retrieve and more fully describes the possible noises than SNR. Additionally, many designers believe that increasing the reflector could improve accuracy continuously or realize multi-resolution measurement. However, they ignore some certain criteria that the reflector location must satisfy. The reachable maximum accuracy by every increase of a reflector is also presented. A SAW temperature sensor system using 128° YX-LiNbO3 is designed to verify the above theoretical analysis. PMID:26492251

  14. Accuracy assessment of high frequency 3D ultrasound for digital impression-taking of prepared teeth

    NASA Astrophysics Data System (ADS)

    Heger, Stefan; Vollborn, Thorsten; Tinschert, Joachim; Wolfart, Stefan; Radermacher, Klaus

    2013-03-01

    Silicone based impression-taking of prepared teeth followed by plaster casting is well-established but potentially less reliable, error-prone and inefficient, particularly in combination with emerging techniques like computer aided design and manufacturing (CAD/CAM) of dental prosthesis. Intra-oral optical scanners for digital impression-taking have been introduced but until now some drawbacks still exist. Because optical waves can hardly penetrate liquids or soft-tissues, sub-gingival preparations still need to be uncovered invasively prior to scanning. High frequency ultrasound (HFUS) based micro-scanning has been recently investigated as an alternative to optical intra-oral scanning. Ultrasound is less sensitive against oral fluids and in principal able to penetrate gingiva without invasively exposing of sub-gingival preparations. Nevertheless, spatial resolution as well as digitization accuracy of an ultrasound based micro-scanning system remains a critical parameter because the ultrasound wavelength in water-like media such as gingiva is typically smaller than that of optical waves. In this contribution, the in-vitro accuracy of ultrasound based micro-scanning for tooth geometry reconstruction is being investigated and compared to its extra-oral optical counterpart. In order to increase the spatial resolution of the system, 2nd harmonic frequencies from a mechanically driven focused single element transducer were separated and corresponding 3D surface models were calculated for both fundamentals and 2nd harmonics. Measurements on phantoms, model teeth and human teeth were carried out for evaluation of spatial resolution and surface detection accuracy. Comparison of optical and ultrasound digital impression taking indicate that, in terms of accuracy, ultrasound based tooth digitization can be an alternative for optical impression-taking.

  15. Assessing the impact of measurement frequency on accuracy and uncertainty of water quality data

    NASA Astrophysics Data System (ADS)

    Helm, Björn; Schiffner, Stefanie; Krebs, Peter

    2014-05-01

    Physico-chemical water quality is a major objective for the evaluation of the ecological state of a river water body. Physical and chemical water properties are measured to assess the river state, identify prevalent pressures and develop mitigating measures. Regularly water quality is assessed based on weekly to quarterly grab samples. The increasing availability of online-sensor data measured at a high frequency allows for an enhanced understanding of emission and transport dynamics, as well as the identification of typical and critical states. In this study we present a systematic approach to assess the impact of measurement frequency on the accuracy and uncertainty of derived aggregate indicators of environmental quality. High frequency measured (10 min-1 and 15 min-1) data on water temperature, pH, turbidity, electric conductivity and concentrations of dissolved oxygen nitrate, ammonia and phosphate are assessed in resampling experiments. The data is collected at 14 sites in eastern and northern Germany representing catchments between 40 km2 and 140 000 km2 of varying properties. Resampling is performed to create series of hourly to quarterly frequency, including special restrictions like sampling at working hours or discharge compensation. Statistical properties and their confidence intervals are determined in a bootstrapping procedure and evaluated along a gradient of sampling frequency. For all variables the range of the aggregate indicators increases largely in the bootstrapping realizations with decreasing sampling frequency. Mean values of electric conductivity, pH and water temperature obtained with monthly frequency differ in average less than five percent from the original data. Mean dissolved oxygen, nitrate and phosphate had in most stations less than 15 % bias. Ammonia and turbidity are most sensitive to the increase of sampling frequency with up to 30 % in average and 250 % maximum bias at monthly sampling frequency. A systematic bias is recognized

  16. Optical fiber spectral attenuation measurement by using tunable laser sources to improve accuracy and uncertainty

    NASA Astrophysics Data System (ADS)

    Seah, Chee Hwee; Zhang, Jing; Xiang, Ning

    2015-07-01

    With reference to the IEC 60793-1-140 international standard of optical fibre measurement methods and test procedures in attenuation, we studied the optical fibre attenuation measurement by cut-back method using tuneable lasers source. By using a power stabilised laser source, we measured the fibre attenuation in the wavelength range from 1270 nm to 1350nm and from 1520 nm to 1620 nm using `cut-back' technique. The power measurement before and after cut-back have better repeatability. Besides, the evaluation of the splicing losses before and after cut-back as well as the evaluation of effective refractive index (Neff) will improve the accuracy in calculating the fibre attenuation. Our method will improve accuracy and reduce uncertainties in the measurement and thus enable us to establish our own optical fibre spectral attenuation standard.

  17. Accuracy of self-reported and measured anthropometric data in the inpatient population.

    PubMed

    Babiarczyk, Beata; Sternal, Danuta

    2015-12-01

    Self-reported body mass index (BMI) is commonly used to assess nutritional status. The aim of the study was to assess the accuracy of self-reported and measured data obtained from the inpatient population. A total of 296 individuals admitted to five hospital wards were included in the study. Patients provided details of their height and weight, and measurements of height and weight were subsequently taken. BMI measurements were calculated from both the self-reported and the measured data. In general, the study participants overestimated their height and underestimated their weight. Older people and women were significantly more likely to overestimate their height, whereas better educated people were more likely to underestimate their weight. Inaccurate height and weight reporting led to BMI values being underestimated. The findings of this study support previously published research questioning the accuracy of self-reported height and weight measurements. PMID:24758279

  18. A High Accuracy Method for Semi-supervised Information Extraction

    SciTech Connect

    Tratz, Stephen C.; Sanfilippo, Antonio P.

    2007-04-22

    Customization to specific domains of dis-course and/or user requirements is one of the greatest challenges for today’s Information Extraction (IE) systems. While demonstrably effective, both rule-based and supervised machine learning approaches to IE customization pose too high a burden on the user. Semi-supervised learning approaches may in principle offer a more resource effective solution but are still insufficiently accurate to grant realistic application. We demonstrate that this limitation can be overcome by integrating fully-supervised learning techniques within a semi-supervised IE approach, without increasing resource requirements.

  19. [The radial velocity measurement accuracy of different spectral type low resolution stellar spectra at different signal-to-noise ratio].

    PubMed

    Wang, Feng-Fei; Luo, A-Li; Zhao, Yong-Heng

    2014-02-01

    The radial velocity of the star is very important for the study of the dynamics structure and chemistry evolution of the Milky Way, is also an useful tool for looking for variable or special objects. In the present work, we focus on calculating the radial velocity of different spectral types of low-resolution stellar spectra by adopting a template matching method, so as to provide effective and reliable reference to the different aspects of scientific research We choose high signal-to-noise ratio (SNR) spectra of different spectral type stellar from the Sloan Digital Sky Survey (SDSS), and add different noise to simulate the stellar spectra with different SNR. Then we obtain theradial velocity measurement accuracy of different spectral type stellar spectra at different SNR by employing a template matching method. Meanwhile, the radial velocity measurement accuracy of white dwarf stars is analyzed as well. We concluded that the accuracy of radial velocity measurements of early-type stars is much higher than late-type ones. For example, the 1-sigma standard error of radial velocity measurements of A-type stars is 5-8 times as large as K-type and M-type stars. We discuss the reason and suggest that the very narrow lines of late-type stars ensure the accuracy of measurement of radial velocities, while the early-type stars with very wide Balmer lines, such as A-type stars, become sensitive to noise and obtain low accuracy of radial velocities. For the spectra of white dwarfs stars, the standard error of radial velocity measurement could be over 50 km x s(-1) because of their extremely wide Balmer lines. The above conclusion will provide a good reference for stellar scientific study. PMID:24822441

  20. Development of an optical feedback based high accuracy beam transmissometer

    NASA Astrophysics Data System (ADS)

    Bartz, Robert

    1987-11-01

    The Phase I research has addressed the need for spectral light transmission data. Over the years the oceanographic community has repeatedly asked for a transmissometer operating at other wavelengths, specifically blue and green. The existing Sea Tech transmissometer is only available with a red LED, (light emitting diode) light source, mainly because LED's at shorter wavelengths have much lower power output. The primary objective of Phase I research was to determine if the transmissometer could be redesigned using LED's of other wavelengths. Constraints imposed on the new design was to achieve the same high performance inherent in the existing red transmissometer that has served the oceanic community so well for over 10 years. During the research performed in Phase I of this project a methodology and technique has been successfully developed for the stabilization of low power LED light sources to be used in the transmissometer. During the Phase I research, both red and blue LED's were evaluated in a optical bridge configuration allowing stabilization of the LED's using optical feedback. The LED's were installed in a collimator having a spatial filter 0.25 mm in diameter and a lens with a focal length of 60 mm resulting in a collimation angle of 4.16 milliradians in air. This same high degree of collimation is used in the existing Sea Tech red transmissometer.

  1. Precision and accuracy of 3D lower extremity residua measurement systems

    NASA Astrophysics Data System (ADS)

    Commean, Paul K.; Smith, Kirk E.; Vannier, Michael W.; Hildebolt, Charles F.; Pilgram, Thomas K.

    1996-04-01

    Accurate and reproducible geometric measurement of lower extremity residua is required for custom prosthetic socket design. We compared spiral x-ray computed tomography (SXCT) and 3D optical surface scanning (OSS) with caliper measurements and evaluated the precision and accuracy of each system. Spiral volumetric CT scanned surface and subsurface information was used to make external and internal measurements, and finite element models (FEMs). SXCT and OSS were used to measure lower limb residuum geometry of 13 below knee (BK) adult amputees. Six markers were placed on each subject's BK residuum and corresponding plaster casts and distance measurements were taken to determine precision and accuracy for each system. Solid models were created from spiral CT scan data sets with the prosthesis in situ under different loads using p-version finite element analysis (FEA). Tissue properties of the residuum were estimated iteratively and compared with values taken from the biomechanics literature. The OSS and SXCT measurements were precise within 1% in vivo and 0.5% on plaster casts, and accuracy was within 3.5% in vivo and 1% on plaster casts compared with caliper measures. Three-dimensional optical surface and SXCT imaging systems are feasible for capturing the comprehensive 3D surface geometry of BK residua, and provide distance measurements statistically equivalent to calipers. In addition, SXCT can readily distinguish internal soft tissue and bony structure of the residuum. FEM can be applied to determine tissue material properties interactively using inverse methods.

  2. TU-A-12A-12: Improved Airway Measurement Accuracy for Low Dose Quantitative CT (qCT) Using Statistical (ASIR), at Reduced DFOV, and High Resolution Kernels in a Phantom and Swine Model

    SciTech Connect

    Yadava, G; Imai, Y; Hsieh, J

    2014-06-15

    Purpose: Quantitative accuracy of Iodine Hounsfield Unit (HU) in conventional single-kVp scanning is susceptible to beam-hardening effect. Dual-energy CT has unique capabilities of quantification using monochromatic CT images, but this scanning mode requires the availability of the state-of-the-art CT scanner and, therefore, is limited in routine clinical practice. Purpose of this work was to develop a beam-hardening-correction (BHC) for single-kVp CT that can linearize Iodine projections at any nominal energy, apply this approach to study Iodine response with respect to keV, and compare with dual-energy based monochromatic images obtained from material-decomposition using 80kVp and 140kVp. Methods: Tissue characterization phantoms (Gammex Inc.), containing solid-Iodine inserts of different concentrations, were scanned using GE multi-slice CT scanner at 80, 100, 120, and 140 kVp. A model-based BHC algorithm was developed where Iodine was estimated using re-projection of image volume and corrected through an iterative process. In the correction, the re-projected Iodine was linearized using a polynomial mapping between monochromatic path-lengths at various nominal energies (40 to 140 keV) and physically modeled polychromatic path-lengths. The beam-hardening-corrected 80kVp and 140kVp images (linearized approximately at effective energy of the beam) were used for dual-energy material-decomposition in Water-Iodine basis-pair followed by generation of monochromatic images. Characterization of Iodine HU and noise in the images obtained from singlekVp with BHC at various nominal keV, and corresponding dual-energy monochromatic images, was carried out. Results: Iodine HU vs. keV response from single-kVp with BHC and dual-energy monochromatic images were found to be very similar, indicating that single-kVp data may be used to create material specific monochromatic equivalent using modelbased projection linearization. Conclusion: This approach may enable quantification of

  3. Estimated accuracy of ground-based liquid water measurements during FIRE

    NASA Technical Reports Server (NTRS)

    Snider, Jack B.

    1990-01-01

    Since on goal of the First ISCCP Regional Experiment (FIRE) project is to improve our understanding of the relationships between cloud microphysics and cloud reflectivity, it is important that the accuracy of remote liquid measurements by microwave radiometry be thoroughly understood. The question is particularly relevant since the uncertainty in the absolute value of the radiometric liquid measurement is greatest at low liquid water contents (less than 0.1 mm). However it should be stressed that although uncertainty exists in the absolute value of liquid, it is well known that the observed radiometric signal is proportional to the amount of liquid in the antenna beam. As a result, changes in amounts of liquid are known to greater accuracy than the absolute value, which may contain a bias. Here, an assessment of the liquid measurement accuracy attained at San Nicolas Island (SNI) is presented. The vapor and liquid water data shown were computed from the radiometric brightness temperatures using statistical retrieval algorithms. The retrieval coefficients were derived from the 69 soundings made by Colorado State University during the SNI observations. Sources of error in the vapor and liquid measurements include cross-talk in the retrieval algorithms (not a factor at low liquid contents), uncertainties in the brightness temperature measurement, and uncertainties in the vapor and liquid attenuation coefficients. The relative importance of these errors is discussed. For the retrieval of path-integrated liquid water, the greatest uncertainty is caused by the temperature dependence of the absorption at microwave frequencies. As a result, the accuracy of statistical retrieval of liquid depends to large measure upon how representative the a priori radiosonde data are of the conditions prevailing during the measurements. The microwave radiometer measurements at SNI were supplemented by an infrared (IR) radiometer modified for measurement of cloud-base temperature. Thus

  4. Phishtest: Measuring the Impact of Email Headers on the Predictive Accuracy of Machine Learning Techniques

    ERIC Educational Resources Information Center

    Tout, Hicham

    2013-01-01

    The majority of documented phishing attacks have been carried by email, yet few studies have measured the impact of email headers on the predictive accuracy of machine learning techniques in detecting email phishing attacks. Research has shown that the inclusion of a limited subset of email headers as features in training machine learning…

  5. Classification Accuracy of Brief Parent Report Measures of Language Development in Spanish-Speaking Toddlers

    ERIC Educational Resources Information Center

    Guiberson, Mark; Rodriguez, Barbara L.; Dale, Philip S.

    2011-01-01

    Purpose: The purpose of the current study was to examine the concurrent validity and classification accuracy of 3 parent report measures of language development in Spanish-speaking toddlers. Method: Forty-five Spanish-speaking parents and their 2-year-old children participated. Twenty-three children had expressive language delays (ELDs) as…

  6. Examining the Classification Accuracy of a Vocabulary Screening Measure with Preschool Children

    ERIC Educational Resources Information Center

    Marcotte, Amanda M.; Clemens, Nathan H.; Parker, Christopher; Whitcomb, Sara A.

    2016-01-01

    This study investigated the classification accuracy of the "Dynamic Indicators of Vocabulary Skills" (DIVS) as a preschool vocabulary screening measure. With a sample of 240 preschoolers, fall and winter DIVS scores were used to predict year-end vocabulary risk using the 25th percentile on the "Peabody Picture Vocabulary Test--Third…

  7. Accuracy of Satellite-Measured Wave Heights in the Australian Region for Wave Power Applications

    ERIC Educational Resources Information Center

    Meath, Sian E.; Aye, Lu; Haritos, Nicholas

    2008-01-01

    This article focuses on the accuracy of satellite data, which may then be used in wave power applications. The satellite data are compared to data from wave buoys, which are currently considered to be the most accurate of the devices available for measuring wave characteristics. This article presents an analysis of satellite- (Topex/Poseidon) and…

  8. Accuracy of PARTwear Inertial Sensor and Optojump Optical Measurement System for Measuring Ground Contact Time During Running.

    PubMed

    Ammann, Rahel; Taube, Wolfgang; Wyss, Thomas

    2016-07-01

    Ammann, R, Taube, W, and Wyss, T. Accuracy of PARTwear inertial sensor and Optojump optical measurement system for measuring ground contact time during running. J Strength Cond Res 30(7): 2057-2063, 2016-The aim of this study was to validate the detection of ground contact time (GCT) during running in 2 differently working systems: a small inertial measurement sensor, PARTwear (PW), worn on the shoe laces, and the optical measurement system, Optojump (OJ), placed on the track. Twelve well-trained subjects performed 12 runs each on an indoor track at speeds ranging from 3.0 to 9.0 m·s. GCT of one step per run (total 144) was simultaneously obtained by the PW, the OJ, and a high-speed video camera (HSC), whereby the latter served as reference system. The sampling rate was 1,000 Hz for all methods. Compared with the HSC, the PW and the OJ systems underestimated GCT by -1.3 ± 6.1% and -16.5 ± 6.7% (p-values ≤ 0.05), respectively. The intraclass correlation coefficients between PW and HSC and between OJ and HSC were 0.984 and 0.853 (p-values < 0.001), respectively. Despite the constant systematic underestimation of GCT, analyses indicated that PW successfully recorded GCT over a wide range of speeds. However, results showed only moderate validity for the OJ system, with increasing errors when speed decreased. In conclusion, the PW proved to be a highly useful and valid application, and its use can be recommended not only for laboratory settings but also for field applications. In contrast, data on GCT obtained by OJ during running must be treated with caution, specifically when running speed changes or when comparisons are made with GCT data collected by other measurement systems. PMID:26677827

  9. A High Accuracy Hybrid Navigation System for Unmanned Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Kumagai, Hideo; Numajima, Toru; Sugimoto, Sueo

    The development of small, light weight, low power navigation system for guidance of both tethered and autonomous Unmanned Underwater Vehicle (UUV) is required in applications such as deep salvage, oil and gas well head and pipe line laying and maintenance, etc. All have stringent position requirements in order to define target locations followings the initial find, minimize search time for return missions, as well as support of autopilot functions. In these applications mainly an accurate Sonar Doppler Velocity Log (DVL) was used for Inertial Navigation System (INS) error corrections. But the settlement of DVL is not affordable to various UUV so that not convenient to low cost and small UUV. In this paper we propose a new algorithm for combining the low cost but highly accurate INS with Water Screw Speed (WSS) of the UUV efficiently. In order to evaluate our algorithm we produced the data acquisition system and after several experimental run, we simulated this algorithm searching the error correlation time and noise variance of these estimations.

  10. Generation of launch windows for high-accuracy lunar trajectories

    NASA Astrophysics Data System (ADS)

    Yim, Shing-Yik; Gong, Shengping; Baoyin, Hexi

    2015-09-01

    The purpose of this paper is to systematically establish in arbitrary timespan a full set of instantaneous ground launch windows for certain accurate three-dimensional asymmetric free return circumlunar trajectories tailored to human lunar missions for China, and in general propose a novel methodology useful for determining ground launch windows for other Earth-to-Moon trajectories. Using time-varying spherical trigonometry, an analytical design method for finding ground launch windows is developed with two-body model assumption. Windows appear when the Moon at arrival time and the Earth parking orbit nodes on lunar orbit plane have similar right ascensions. The numerical first guesses obtained almost instantly are within minutes of accurate solutions and refined to highly accurate trajectories by differential corrections of only one phase. A translunar launch window plot visualizing all monthly and daily launch windows differentiating two types of translunar injections is created. The method proposed can be used for automated generation of complete trajectory sets, and provide the basis for the preparation of launch timetables satisfying lunar mission requirements.

  11. High temperature measuring device

    DOEpatents

    Tokarz, Richard D.

    1983-01-01

    A temperature measuring device for very high design temperatures (to 2,000.degree. C.). The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensionally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.

  12. Improving accuracy of cell and chromophore concentration measurements using optical density

    PubMed Central

    2013-01-01

    Background UV–vis spectrophotometric optical density (OD) is the most commonly-used technique for estimating chromophore formation and cell concentration in liquid culture. OD wavelength is often chosen with little thought given to its effect on the quality of the measurement. Analysis of the contributions of absorption and scattering to the measured optical density provides a basis for understanding variability among spectrophotometers and enables a quantitative evaluation of the applicability of the Beer-Lambert law. This provides a rational approach for improving the accuracy of OD measurements used as a proxy for direct dry weight (DW), cell count, and pigment levels. Results For pigmented organisms, the choice of OD wavelength presents a tradeoff between the robustness and the sensitivity of the measurement. The OD at a robust wavelength is primarily the result of light scattering and does not vary with culture conditions; whereas, the OD at a sensitive wavelength is additionally dependent on light absorption by the organism’s pigments. Suitably robust and sensitive wavelengths are identified for a wide range of organisms by comparing their spectra to the true absorption spectra of dyes. The relative scattering contribution can be reduced either by measurement at higher OD, or by the addition of bovine serum albumin. Reduction of scattering or correlation with off-peak light attenuation provides for more accurate assessment of chromophore levels within cells. Conversion factors between DW, OD, and colony-forming unit density are tabulated for 17 diverse organisms to illustrate the scope of variability of these correlations. Finally, an inexpensive short pathlength LED-based flow cell is demonstrated for the online monitoring of growth in a bioreactor at culture concentrations greater than 5 grams dry weight per liter which would otherwise require off-line dilutions to obtain non-saturated OD measurements. Conclusions OD is most accurate as a time

  13. Spaceborne lidar measurement accuracy - Simulation of aerosol, cloud, molecular density, and temperature retrievals

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Morley, B. M.; Browell, E. V.

    1982-01-01

    In connection with studies concerning the use of an orbiting optical radar (lidar) to conduct aerosol and cloud measurements, attention has been given to the accuracy with which lidar return signals could be measured. However, signal-measurement error is not the only source of error which can affect the accuracy of the derived information. Other error sources are the assumed molecular-density and atmospheric-transmission profiles, and the lidar calibration factor (which relates signal to backscatter coefficient). The present investigation has the objective to account for the effects of all these errors sources for several realistic combinations of lidar parameters, model atmospheres, and background lighting conditions. In addition, a procedure is tested and developed for measuring density and temperature profiles with the lidar, and for using the lidar-derived density profiles to improve aerosol retrievals.

  14. Stitching accuracy measurement system for EB direct writing and electron-beam projection lithography (EPL)

    NASA Astrophysics Data System (ADS)

    Tamura, Takao; Ema, Takahiro; Nozue, Hiroshi; Sugahara, Tamoya; Sugano, Akio; Nitta, Jun

    2001-08-01

    We have developed a stitching accuracy measurement system for electron beam (EB) direct writing and electron beam projection lithography (EPL). This system calculates the amount of a stitching error between two EB shots from SEM images. It extracts a representative edge line of each pattern from the graphical format files (BMP, JPEG etc.) of SEM images and calculates a distance between each edge line as a stitching error. For obtaining a higher stitching accuracy of EB direct writing or EPL machines, it can analyze the relation of amounts and direction of a stitching error with a field size or a field position of these machines. We could successfully measure about 2.0 nm as a stitching error value in 0.1 micrometers L/S resist patterns on a bare-Si substrate and obtain 1.2 nm (3(sigma) ) as the measurement repeatability. It took 2.5 sec. for this system to measure one stitching region.

  15. Measuring the accuracy and precision of quantitative coronary angiography using a digitally simulated test phantom

    NASA Astrophysics Data System (ADS)

    Morioka, Craig A.; Whiting, James S.; LeFree, Michelle T.

    1998-06-01

    Quantitative coronary angiography (QCA) diameter measurements have been used as an endpoint measurement in clinical studies involving therapies to reduce coronary atherosclerosis. The accuracy and precision of the QCA measure can affect the sample size and study conclusions of a clinical study. Measurements using x-ray test phantoms can underestimate the precision and accuracy of the actual arteries in clinical digital angiograms because they do not contain complex patient structures. Determining the clinical performance of QCA algorithms under clinical conditions is difficult because: (1) no gold standard test object exists in clinical images, (2) phantom images do not have any structured background noise. We purpose the use of computer simulated arteries as a replacement for traditional angiographic test phantoms to evaluate QCA algorithm performance.

  16. Disturbance observer and feedforward design for a 2-DOF high-speed/high-accuracy robotic system

    NASA Astrophysics Data System (ADS)

    Cui, Jing; Chu, Zhongyi

    2005-12-01

    In this paper, a novel 2-DOF high-speed/high-accuracy robotic system is proposed, which consists of two permanent linear DC servomotors and a planar parallel mechanism. Analysis of robotic dynamical model verifies that load variation is violent. Due to the direct-drive principle of a linear motor, the load disturbance can have a significant effect on position accuracy. For this purpose, a discrete-time disturbance observer, feedback controller and ZPECT feedforward controller is presented. The disturbance observer, which is applied to the plant velocity loop, provides robustness for design of both the feedback controller and the feedforward controller. The feedback controller is intended to make the command following properties fast, and the feedforward term realized as a Zero Phase Error Tracking Controller improves tracking. In the experiment, robotic max acceleration is equal to 20m/s2, max velocity is more than 1 m/s, and resolution is 0.5 μm. While the tracking errors are less than 50 μm, the steady-state errors are less than 1 μm, and steady time is less then 42 ms. Experiment results show that: high-performance motion system can be obtained with this discrete-time controller, even in large load variance motion system.

  17. Systematic Characterization of High Mass Accuracy Influence on False Discovery and Probability Scoring in Peptide Mass Fingerprinting

    PubMed Central

    Dodds, Eric D.; Clowers, Brian H.; Hagerman, Paul J.; Lebrilla, Carlito B.

    2009-01-01

    While the bearing of mass measurement error upon protein identification is sometimes underestimated, uncertainty in observed peptide masses unavoidably translates to ambiguity in subsequent protein identifications. While ongoing instrumental advances continue to make high accuracy mass spectrometry (MS) increasingly accessible, many proteomics experiments are still conducted with rather large mass error tolerances. Additionally, the ranking schemes of most protein identification algorithms do not include a meaningful incorporation of mass measurement error. This report provides a critical evaluation of mass error tolerance as it pertains to false positive peptide and protein associations resulting from peptide mass fingerprint (PMF) database searching. High accuracy, high resolution PMFs of several model proteins were obtained using matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS). Varying levels of mass accuracy were simulated by systematically modulating the mass error tolerance of the PMF query and monitoring the effect on figures of merit indicating the PMF quality. Importantly, the benefits of decreased mass error tolerance are not manifest in Mowse scores when operating at tolerances in the low parts per million range, but become apparent with the consideration of additional metrics that are often overlooked. Furthermore, the outcomes of these experiments support the concept that false discovery is closely tied to mass measurement error in PMF analysis. Clear establishment of this relation demonstrates the need for mass error aware protein identification routines and argues for a more prominent contribution of high accuracy mass measurement to proteomic science. PMID:17980142

  18. An experimental study of the accuracy in measurement of modulation transfer function using an edge method

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Hoon; Kim, Ye-seul; Park, Hye-Suk; Lee, Young-Jin; Kim, Hee-Joung

    2015-03-01

    Image evaluation is necessary in digital radiography (DR) which is widely used in medical imaging. Among parameters of image evaluation, modulation transfer function (MTF) is the important factor in the field of medical imaging and necessary to obtain detective quantum efficiency (DQE) which represents overall performance of the detector signal-to-noise ratio. However, the accurate measurement of MTF is still not easy because of geometric effect, electric noise, quantum noise, and truncation error. Therefore, in order to improve accuracy of MTF, four experimental methods were tested in this study such as changing the tube current, applying smoothing method in edge spread function (ESF), adjusting line spread function (LSF) range, and changing tube angle. Our results showed that MTF's fluctuation was decreased by high tube current and smoothing method. However, tube current should not exceed detector saturation and smoothing in ESF causes a distortion in ESF and MTF. In addition, decreasing LSF range diminished fluctuation and the number of sampling in MTF and high tube angle generates degradation in MTF. Based on these results, excessively low tube current and the smoothing method should be avoided. Also, optimal range of LSF considering reduction of fluctuation and the number of sampling in MTF was necessary and precise tube angle is essential to obtain an accurate MTF. In conclusion, our results demonstrated that accurate MTF can be acquired.

  19. The measurement of linear and angular displacements in prototype aircraft - Instrumentation, calibration and operational accuracy

    NASA Astrophysics Data System (ADS)

    Storm van Leeuwen, Sam

    The design and development of angular displacement transducers for flight test instrumentation systems are considered. Calibration tools, developed to meet the accuracy requirements, allowed in situ calibration with short turn around times. The design of the control surface deflection measurement channels for the Fokker 100 prototype aircraft is discussed in detail. It is demonstrated that a bellows coupling provides accurate results, and that the levers and push-pull rod drive mechanisms perform well. The results suggest that a complex mechanical drive mechanism reduces the system accuracy.

  20. Surface accuracy measurement sensor test on a 50-meter antenna surface model

    NASA Technical Reports Server (NTRS)

    Spiers, R. B.; Burcher, E. E.; Stump, C. W.; Saunders, C. G.; Brooks, G. F.

    1984-01-01

    The Surface Accuracy Measurement Sensor (SAMS) is a telescope with a focal plane photo electric detector that senses the lateral position of light source targets in its field of view. After extensive laboratory testing the engineering breadboard sensor system was installed and tested on a 30 degree segment of a 50-meter diameter, mesh surface, antenna model. Test results correlated well with the laboratory tests and indicated accuracies of approximately 0.59 arc seconds at 21 meters range. Test results are presented and recommendations given for sensor improvements.

  1. Quantitative Proteomics using Nano-LC with High Accuracy Mass Spectrometry

    SciTech Connect

    Pasa-Tolic, Liljiana; Jacobs, Jon M.; Qian, Weijun; Smith, Richard D.

    2008-01-29

    Despite significant advances in LC-MS based technologies, challenges remain in implementing a proteomics platform for routine clinical applications. These include the needed robustness as well as the sensitivity and dynamic range of detection to both effectively address extremely small tissue samples, for example microdissected or biopsy tissues, or high dynamic range samples, such as blood plasma. Other key components include providing the needed throughput to enable statistically meaningful number of analyses for clinical setting within a robust platform that utilizes effective quantitative approaches for high accuracy and reproducibility. This chapter describes the key components of a nanoLC- MS based technological approach that is designed to target these challenges by virtue of enhancing sensitivity, dynamic range coverage, and throughput, for the generation of robust quantitative measurements in support of clinical studies.

  2. Comparison between predicted and actual accuracies for an Ultra-Precision CNC measuring machine

    SciTech Connect

    Thompson, D.C.; Fix, B.L.

    1995-05-30

    At the 1989 CIRP annual meeting, we reported on the design of a specialized, ultra-precision CNC measuring machine, and on the error budget that was developed to guide the design process. In our paper we proposed a combinatorial rule for merging estimated and/or calculated values for all known sources of error, to yield a single overall predicted accuracy for the machine. In this paper we compare our original predictions with measured performance of the completed instrument.

  3. Radius of Curvature Measurements: An Independent Look at Accuracy Using Novel Optical Metrology

    NASA Technical Reports Server (NTRS)

    Taylor, Bryon; Kahan, Mark; Russell, Kevin (Technical Monitor)

    2002-01-01

    The AMSD (Advanced Mirror System Demonstrator) program mirror specifications include the ability to manufacture the mirror to a radius of curvature of 10 m +/- 1 mm and to control its radius at 30K to the same specification. Therefore, it is necessary for the Government Team to be able to measure mirror radius of curvature to an accuracy of better than 0.5 mm. This presentation discusses a novel optical metrology system for measuring radius of curvature.

  4. High-Reproducibility and High-Accuracy Method for Automated Topic Classification

    NASA Astrophysics Data System (ADS)

    Lancichinetti, Andrea; Sirer, M. Irmak; Wang, Jane X.; Acuna, Daniel; Körding, Konrad; Amaral, Luís A. Nunes

    2015-01-01

    Much of human knowledge sits in large databases of unstructured text. Leveraging this knowledge requires algorithms that extract and record metadata on unstructured text documents. Assigning topics to documents will enable intelligent searching, statistical characterization, and meaningful classification. Latent Dirichlet allocation (LDA) is the state of the art in topic modeling. Here, we perform a systematic theoretical and numerical analysis that demonstrates that current optimization techniques for LDA often yield results that are not accurate in inferring the most suitable model parameters. Adapting approaches from community detection in networks, we propose a new algorithm that displays high reproducibility and high accuracy and also has high computational efficiency. We apply it to a large set of documents in the English Wikipedia and reveal its hierarchical structure.

  5. Determining the accuracies of sea-surface temperatures derived from measurements of MODIS and VIIRS

    NASA Astrophysics Data System (ADS)

    Minnett, P. J.; Kilpatrick, K. A.; Podesta, G. P.; Izaguirre, M.; Williams, E.; Walsh, S.

    2015-12-01

    The appropriate application of sea-surface temperatures (SSTs) derived from MODIS and VIIRS requires knowledge of the errors and uncertainties of the SST fields. The accuracies of the SSTs are determined by comparison with independent measurements, usually derived from drifting and moored buoys, and ship-board radiometers. By using similar cloud detection and clear-sky atmospheric correction algorithms to derived SST from both MODIS's on Terra and Aqua, and the VIIRS on S-NPP a consistent time series of SSTs can be derived from the first useful Terra MODIS data in 2000 to the present, and by using the same approach to assess their accuracies, a consistent set of errors and uncertainties can also be derived. The presentation will provide a summary of recently modified algorithms used to derive SSTs from the MODIS's and VIIRS, and discuss the accuracies of the derived fields, including recent improvements to the VIIRS atmospheric correction algorithm to reduce the effects of instrumental artifacts.

  6. Camera model and calibration process for high-accuracy digital image metrology of inspection planes

    NASA Astrophysics Data System (ADS)

    Correia, Bento A. B.; Dinis, Joao

    1998-10-01

    High accuracy digital image based metrology must rely on an integrated model of image generation that is able to consider simultaneously the geometry of the camera vs. object positioning, and the conversion of the optical image on the sensor into an electronic digital format. In applications of automated visual inspection involving the analysis of approximately plane objects these models are generally simplified in order to facilitate the process of camera calibration. In this context, the lack of rigor in the determination of the intrinsic parameters in such models is particularly relevant. Aiming at the high accuracy metrology of contours of objects lying on an analysis plane, and involving sub-pixel measurements, this paper presents a three-stage camera model that includes an extrinsic component of perspective distortion and the intrinsic components of radial lens distortion and sensor misalignment. The later two factors are crucial in applications of machine vision that rely on the use of low cost optical components. A polynomial model for the negative radial lens distortion of wide field of view CCTV lenses is also established.

  7. MAPU 2.0: high-accuracy proteomes mapped to genomes

    PubMed Central

    Gnad, Florian; Oroshi, Mario; Birney, Ewan; Mann, Matthias

    2009-01-01

    The MAPU 2.0 database contains proteomes of organelles, tissues and cell types measured by mass spectrometry (MS)-based proteomics. In contrast to other databases it is meant to contain a limited number of experiments and only those with very high-resolution and -accuracy data. MAPU 2.0 displays the proteomes of organelles, tissues and body fluids or conversely displays the occurrence of proteins of interest in all these proteomes. The new release addresses MS-specific problems including ambiguous peptide-to-protein assignments and it provides insight into general functional features on the protein level ranging from gene ontology classification to comprehensive SwissProt annotation. Moreover, the derived proteomic data are used to annotate the genomes using Distributed Annotation Service (DAS) via EnsEMBL services. MAPU 2.0 is a model for a database specifically designed for high-accuracy proteomics and a member of the ProteomExchange Consortium. It is available on line at http://www.mapuproteome.com. PMID:18948283

  8. Testing of the high accuracy inertial navigation system in the Shuttle Avionics Integration Lab

    NASA Technical Reports Server (NTRS)

    Strachan, Russell L.; Evans, James M.

    1991-01-01

    The description, results, and interpretation is presented of comparison testing between the High Accuracy Inertial Navigation System (HAINS) and KT-70 Inertial Measurement Unit (IMU). The objective was to show the HAINS can replace the KT-70 IMU in the space shuttle Orbiter, both singularly and totally. This testing was performed in the Guidance, Navigation, and Control Test Station (GTS) of the Shuttle Avionics Integration Lab (SAIL). A variety of differences between the two instruments are explained. Four, 5 day test sessions were conducted varying the number and slot position of the HAINS and KT-70 IMUs. The various steps in the calibration and alignment procedure are explained. Results and their interpretation are presented. The HAINS displayed a high level of performance accuracy previously unseen with the KT-70 IMU. The most significant improvement of the performance came in the Tuned Inertial/Extended Launch Hold tests. The HAINS exceeded the 4 hr specification requirement. The results obtained from the SAIL tests were generally well beyond the requirements of the procurement specification.

  9. Automatic and robust extrinsic camera calibration for high-accuracy mobile mapping

    NASA Astrophysics Data System (ADS)

    Goeman, Werner; Douterloigne, Koen; Bogaert, Peter; Pires, Rui; Gautama, Sidharta

    2012-10-01

    A mobile mapping system (MMS) is the answer of the geoinformation community to the exponentially growing demand for various geospatial data with increasingly higher accuracies and captured by multiple sensors. As the mobile mapping technology is pushed to explore its use for various applications on water, rail, or road, the need emerges to have an external sensor calibration procedure which is portable, fast and easy to perform. This way, sensors can be mounted and demounted depending on the application requirements without the need for time consuming calibration procedures. A new methodology is presented to provide a high quality external calibration of cameras which is automatic, robust and fool proof.The MMS uses an Applanix POSLV420, which is a tightly coupled GPS/INS positioning system. The cameras used are Point Grey color video cameras synchronized with the GPS/INS system. The method uses a portable, standard ranging pole which needs to be positioned on a known ground control point. For calibration a well studied absolute orientation problem needs to be solved. Here, a mutual information based image registration technique is studied for automatic alignment of the ranging pole. Finally, a few benchmarking tests are done under various lighting conditions which proves the methodology's robustness, by showing high absolute stereo measurement accuracies of a few centimeters.

  10. PIV measurements and data accuracy analysis of flow in complex terrain

    NASA Astrophysics Data System (ADS)

    Yao, Rentai; Hao, Hongwei; Qiao, Qingdang

    2000-10-01

    In this paper velocity fields and flow visualization in complex terrain in an environmental wind tunnel have been measured using PIV. In addition, it would be useful to appraise the PIV data by comparing the PIV results with those obtained from the well- established point measurement methods, such as constant temperature anemometry (CTA) and Dantec FlowMaster, in order to verify the accuracy of PIV measurements. The results indicate that PIV is a powerful tool for velocity measurements in the environmental wind tunnel.

  11. Symmetrically associated combination method for accuracy verification of Coordinate Measuring Machines

    NASA Astrophysics Data System (ADS)

    Wang, Hongtao; Chen, Xiaohuai; Fei, Yetai

    2008-10-01

    The paper is enlightened by the traditional combination verification method, provides a new detection way to CMM which is the combination of space one-dimension balls combination. It uses one-dimension balls instead of the standard ruler of the tradition combination verification method, adopts special researched detection equipment to CMM making one-dimension balls to three-dimension. The CMM processes the space random line with symmetry associating and comparing measurement method, and then uses the least-squares method to the measured data to obtain the measurement error of the space line, consequently realizes the measurement accuracy detection of the CMM.

  12. Dependence of Dynamic Modeling Accuracy on Sensor Measurements, Mass Properties, and Aircraft Geometry

    NASA Technical Reports Server (NTRS)

    Grauer, Jared A.; Morelli, Eugene A.

    2013-01-01

    The NASA Generic Transport Model (GTM) nonlinear simulation was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of identified parameters in mathematical models describing the flight dynamics and determined from flight data. Measurements from a typical flight condition and system identification maneuver were systematically and progressively deteriorated by introducing noise, resolution errors, and bias errors. The data were then used to estimate nondimensional stability and control derivatives within a Monte Carlo simulation. Based on these results, recommendations are provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using additional flight conditions and parameter estimation methods, as well as a nonlinear flight simulation of the General Dynamics F-16 aircraft, were compared with these recommendations

  13. 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

  14. High accuracy localization of long term evolution based on a new multiple carrier noise model.

    PubMed

    Lee, Wah Ching; Hung, Faan Hei; Tsang, Kim Fung; Wu, Chung Kit; Chi, Hao Ran; Chui, Kwok Tai; Lau, Wing Hong

    2014-01-01

    A high accuracy localization technique using Long Term Evolution (LTE) based on a new and accurate multiple carrier noise model has been developed. In the noise consideration, the LTE multiple carriers phase noise has been incorporated so that a new and accurate noise model is achieved. An experiment was performed to characterize the phase noise of carriers at 2 GHz. The developed noise model was incorporated into LTE localization analysis in a high traffic area in Hong Kong to evaluate the accuracy of localization. The evaluation and analysis reveals that the new localization method achieves an improvement of about 10% accuracy comparing to existing widely adopted schemes. PMID:25436658

  15. High Accuracy Localization of Long Term Evolution Based on a New Multiple Carrier Noise Model

    PubMed Central

    Lee, Wah Ching; Hung, Faan Hei; Tsang, Kim Fung; Wu, Chung Kit; Chi, Hao Ran; Chui, Kwok Tai; Lau, Wing Hong

    2014-01-01

    A high accuracy localization technique using Long Term Evolution (LTE) based on a new and accurate multiple carrier noise model has been developed. In the noise consideration, the LTE multiple carriers phase noise has been incorporated so that a new and accurate noise model is achieved. An experiment was performed to characterize the phase noise of carriers at 2 GHz. The developed noise model was incorporated into LTE localization analysis in a high traffic area in Hong Kong to evaluate the accuracy of localization. The evaluation and analysis reveals that the new localization method achieves an improvement of about 10% accuracy comparing to existing widely adopted schemes. PMID:25436658

  16. High resolution infrared measurements

    NASA Technical Reports Server (NTRS)

    Kessler, B.; Cawley, Robert

    1990-01-01

    Sample ground based cloud radiance data from a high resolution infrared sensor are shown and the sensor characteristics are presented in detail. The purpose of the Infrared Analysis Measurement and Modeling Program (IRAMMP) is to establish a deterministic radiometric data base of cloud, sea, and littoral terrain clutter to be used to advance the design and development of Infrared Search and Track (IRST) systems as well as other infrared devices. The sensor is a dual band radiometric sensor and its description, together with that of the Data Acquisition System (DAS), are given. A schematic diagram of the sensor optics is shown.

  17. High accuracy low-cost videogrammetric system: an application to 6DOF estimation of ship models

    NASA Astrophysics Data System (ADS)

    Nocerino, Erica; Menna, Fabio; Troisi, Salvatore

    2013-04-01

    The article reports the development of an off-line low-cost videogrammetric system for measuring six degrees of freedom (6DOF) of scaled models in ship model basin. Sub-millimeter accuracy is required to measure the floating rigid body movements. To meet this requirement, in depth analyses, exposed in this paper, are performed to choose the most appropriate number of cameras, their configuration and a proper technique for camera synchronization. The proposed system, composed of three consumer-grade High Definition (Full HD) video cameras, is used to record interlaced video sequences at a frequency of 50 frames per second. A special device which emits simultaneously sounds at known frequency and flashes a LED is used to introduce a common event used for an automatic a-posteriori synchronization of video sequences up to 1 msec. The video sequences are synchronized using matching procedures based on cross correlation between audio signals recorded by camcorders. The ship model is targeted with retro illuminated (LEDs) targets whose positions in the ship reference frame are also measured with photogrammetry. The 6DOF of the ship model are estimated on the basis of rigid transformations computed through the image sequences with the tracked active targets. An error analysis is performed with the assumption of the rigid body using the target coordinates known with photogrammetry. The measured synchronization error is used to correct the image trajectories of tracked points. An improvement of the accuracy of a factor 5 was observed for the trial with highest velocity of tracked points (up to 0.35 m/s).

  18. Servo control system for friction drive with ultra-low speed and high accuracy

    NASA Astrophysics Data System (ADS)

    Yang, Shihai; Zhang, Zhenchao

    2008-07-01

    Due to its high accuracy and good performance at low speed, friction drive is widely used in turntable and large astronomical telescopes such as LAMOST and Keck. Especially, friction drives are implemented on the axes of azimuth, altitude and field rotation in LAMOST telescope. This paper describes the study on servo control system for friction drive with ultra-low speed and high accuracy. The principle, constitution, control algorithm and realization of servo system based on friction drive are analyzed and explored.

  19. Theoretical prediction of lung nodule measurement accuracy under different acquisition and reconstruction conditions

    NASA Astrophysics Data System (ADS)

    Hsieh, Jiang; Karau, Kelly

    2004-04-01

    Utilization of computed tomography (CT) for lung cancer screening has attracted significant research interests in recent years. Images reconstructed from CT studies are used for lung nodule characterization and three-dimensional lung lesion sizing. Methodologies have been developed to automatically identify and characterize lung nodules. In this paper, we analyze the impact of acquisition and reconstruction parameters on the accuracy of quantitative lung nodule characterization. The two major data acquisition parameters that impact the accuracy of the lung nodule measurement are acquisition mode and slice aperture. Acquisition mode includes both axial and helical scans. The investigated reconstruction parameters are the reconstruction filters and field-of-view. We first develop theoretical models that predict the system response under various acquisition and reconstruction conditions. These models allow clinicians to compare results under different conditions and make appropriate acquisition and reconstruction decisions. To validate our model, extensive phantom experiments are conducted. Experiments have demonstrated that our analytical models accurately predict the performance parameters under various conditions. Our study indicates that acquisition and reconstruction parameters can significantly impact the accuracy of the nodule volume measurement. Consequently, when conducting quantitative analysis on lung nodules, especially in sequential growth studies, it is important to make appropriate adjustment and correction to maintain the desired accuracy and to ensure effective patient management.

  20. Accuracy of linear measurement in the Galileos cone beam computed tomography under simulated clinical conditions

    PubMed Central

    Ganguly, R; Ruprecht, A; Vincent, S; Hellstein, J; Timmons, S; Qian, F

    2011-01-01

    Objectives The aim of this study was to determine the geometric accuracy of cone beam CT (CBCT)-based linear measurements of bone height obtained with the Galileos CBCT (Sirona Dental Systems Inc., Bensheim, Hessen, Germany) in the presence of soft tissues. Methods Six embalmed cadaver heads were imaged with the Galileos CBCT unit subsequent to placement of radiopaque fiduciary markers over the buccal and lingual cortical plates. Electronic linear measurements of bone height were obtained using the Sirona software. Physical measurements were obtained with digital calipers at the same location. This distance was compared on all six specimens bilaterally to determine accuracy of the image measurements. Results The findings showed no statistically significant difference between the imaging and physical measurements (P > 0.05) as determined by a paired sample t-test. The intraclass correlation was used to measure the intrarater reliability of repeated measures and there was no statistically significant difference between measurements performed at the same location (P > 0.05). Conclusions The Galileos CBCT image-based linear measurement between anatomical structures within the mandible in the presence of soft tissues is sufficiently accurate for clinical use. PMID:21697155

  1. Data supporting the high-accuracy haplotype imputation using unphased genotype data as the references.

    PubMed

    Li, Wenzhi; Xu, Wei; He, Shaohua; Ma, Li; Song, Qing

    2016-09-01

    The data presented in this article is related to the research article entitled "High-accuracy haplotype imputation using unphased genotype data as the references" which reports the unphased genotype data can be used as reference for haplotyping imputation [1]. This article reports different implementation generation pipeline, the results of performance comparison between different implementations (A, B, and C) and between HiFi and three major imputation software tools. Our data showed that the performances of these three implementations are similar on accuracy, in which the accuracy of implementation-B is slightly but consistently higher than A and C. HiFi performed better on haplotype imputation accuracy and three other software performed slightly better on genotype imputation accuracy. These data may provide a strategy for choosing optimal phasing pipeline and software for different studies. PMID:27595130

  2. Improving the Accuracy and Efficiency of Respiratory Rate Measurements in Children Using Mobile Devices

    PubMed Central

    Chiu, Michelle; Dunsmuir, Dustin; Zhou, Guohai; Dumont, Guy A.; Ansermino, J. Mark

    2014-01-01

    The recommended method for measuring respiratory rate (RR) is counting breaths for 60 s using a timer. This method is not efficient in a busy clinical setting. There is an urgent need for a robust, low-cost method that can help front-line health care workers to measure RR quickly and accurately. Our aim was to develop a more efficient RR assessment method. RR was estimated by measuring the median time interval between breaths obtained from tapping on the touch screen of a mobile device. The estimation was continuously validated by measuring consistency (% deviation from the median) of each interval. Data from 30 subjects estimating RR from 10 standard videos with a mobile phone application were collected. A sensitivity analysis and an optimization experiment were performed to verify that a RR could be obtained in less than 60 s; that the accuracy improves when more taps are included into the calculation; and that accuracy improves when inconsistent taps are excluded. The sensitivity analysis showed that excluding inconsistent tapping and increasing the number of tap intervals improved the RR estimation. Efficiency (time to complete measurement) was significantly improved compared to traditional methods that require counting for 60 s. There was a trade-off between accuracy and efficiency. The most balanced optimization result provided a mean efficiency of 9.9 s and a normalized root mean square error of 5.6%, corresponding to 2.2 breaths/min at a respiratory rate of 40 breaths/min. The obtained 6-fold increase in mean efficiency combined with a clinically acceptable error makes this approach a viable solution for further clinical testing. The sensitivity analysis illustrating the trade-off between accuracy and efficiency will be a useful tool to define a target product profile for any novel RR estimation device. PMID:24919062

  3. Accuracy assessment of CKC high-density surface EMG decomposition in biceps femoris muscle

    NASA Astrophysics Data System (ADS)

    Marateb, H. R.; McGill, K. C.; Holobar, A.; Lateva, Z. C.; Mansourian, M.; Merletti, R.

    2011-10-01

    The aim of this study was to assess the accuracy of the convolution kernel compensation (CKC) method in decomposing high-density surface EMG (HDsEMG) signals from the pennate biceps femoris long-head muscle. Although the CKC method has already been thoroughly assessed in parallel-fibered muscles, there are several factors that could hinder its performance in pennate muscles. Namely, HDsEMG signals from pennate and parallel-fibered muscles differ considerably in terms of the number of detectable motor units (MUs) and the spatial distribution of the motor-unit action potentials (MUAPs). In this study, monopolar surface EMG signals were recorded from five normal subjects during low-force voluntary isometric contractions using a 92-channel electrode grid with 8 mm inter-electrode distances. Intramuscular EMG (iEMG) signals were recorded concurrently using monopolar needles. The HDsEMG and iEMG signals were independently decomposed into MUAP trains, and the iEMG results were verified using a rigorous a posteriori statistical analysis. HDsEMG decomposition identified from 2 to 30 MUAP trains per contraction. 3 ± 2 of these trains were also reliably detected by iEMG decomposition. The measured CKC decomposition accuracy of these common trains over a selected 10 s interval was 91.5 ± 5.8%. The other trains were not assessed. The significant factors that affected CKC decomposition accuracy were the number of HDsEMG channels that were free of technical artifact and the distinguishability of the MUAPs in the HDsEMG signal (P < 0.05). These results show that the CKC method reliably identifies at least a subset of MUAP trains in HDsEMG signals from low force contractions in pennate muscles.

  4. Development of distance accuracy measurement program for quality control of diagnostic ultrasound system

    NASA Astrophysics Data System (ADS)

    Kim, Yon-Min; Kim, Moon-Chan; Han, Dong-Kyoon; Cho, Jae-Hwan; Kim, Sang-Hyun

    2013-12-01

    Evaluating the performance of a diagnostic ultrasound system is important. Above all, establishing standards for such evaluations in an objective and systematic way is critical. However, quality control is currently measured based on subjective judgment of an observer. Against this background, this study intended to suggest quantified and objective data that would enable inter-observer variation to be overcome. Five radiological technologists used an ATS-539 multi-purpose ultrasound phantom to conduct measurements in the predetermined method. A digital imaging and communications in medicine (DICOM) standard image was obtained in an ultrasound system by using a self-developed software to measure the accuracy of the distance before the 95% confidence interval was calculated. In order to examine the accuracy of the distance in longitudinal and transverse measurements, we conducted t-tests to evaluate the significance for the results of quality control that was performed manually for the past one year and for the results of quality control that was performed by using software with the same equipment. For the longitudinal and the transverse measurements, the 95% confidence intervals were 100.96-101.29 mm and 83.18-84.26 mm, respectively. The computerized longitudinal measurement showed no significant difference from the manual measurement ( p > 0.05). The results of measurements using of software showed a higher reproducibility.

  5. Accuracy of force and center of pressure measures of the Wii Balance Board

    PubMed Central

    Bartlett, Harrison L.; Ting, Lena H.; Bingham, Jeffrey T.

    2013-01-01

    The Nintendo Wii Balance Board (WBB) is increasingly used as an inexpensive force plate for assessment of postural control; however, no documentation of force and COP accuracy and reliability is publicly available. Therefore, we performed a standard measurement uncertainty analysis on 3 lightly and 6 heavily used WBBs to provide future users with information about the repeatability and accuracy of the WBB force and COP measurements. Across WBBs, we found the total uncertainty of force measurements to be within ±9.1 N, and of COP location within ±4.1 mm. However, repeatability of a single measurement within a board was better (4.5 N, 1.5 mm), suggesting that the WBB is best used for relative measures using the same device, rather than absolute measurement across devices. Internally stored calibration values were comparable to those determined experimentally. Further, heavy wear did not significantly degrade performance. In combination with prior evaluation of WBB performance and published standards for measuring human balance, our study provides necessary information to evaluate the use of the WBB for analysis of human balance control. We suggest the WBB may be useful for low-resolution measurements, but should not be considered as a replacement for laboratory-grade force plates. PMID:23910725

  6. Accuracy of force and center of pressure measures of the Wii Balance Board.

    PubMed

    Bartlett, Harrison L; Ting, Lena H; Bingham, Jeffrey T

    2014-01-01

    The Nintendo Wii Balance Board (WBB) is increasingly used as an inexpensive force plate for assessment of postural control; however, no documentation of force and COP accuracy and reliability is publicly available. Therefore, we performed a standard measurement uncertainty analysis on 3 lightly and 6 heavily used WBBs to provide future users with information about the repeatability and accuracy of the WBB force and COP measurements. Across WBBs, we found the total uncertainty of force measurements to be within ± 9.1N, and of COP location within ± 4.1mm. However, repeatability of a single measurement within a board was better (4.5 N, 1.5mm), suggesting that the WBB is best used for relative measures using the same device, rather than absolute measurement across devices. Internally stored calibration values were comparable to those determined experimentally. Further, heavy wear did not significantly degrade performance. In combination with prior evaluation of WBB performance and published standards for measuring human balance, our study provides necessary information to evaluate the use of the WBB for analysis of human balance control. We suggest the WBB may be useful for low-resolution measurements, but should not be considered as a replacement for laboratory-grade force plates. PMID:23910725

  7. High Accuracy Decoding of User Intentions Using EEG to Control a Lower-Body Exoskeleton*

    PubMed Central

    Kilicarslan, Atilla; Prasad, Saurabh; Grossman, Robert G.; Contreras-Vidal, Jose L.

    2013-01-01

    Brain-Machine Interface (BMI) systems allow users to control external mechanical systems using their thoughts. Commonly used in literature are invasive techniques to acquire brain signals and decode user’s attempted motions to drive these systems (e.g. a robotic manipulator). In this work we use a lower-body exoskeleton and measure the users brain activity using non-invasive electroencephalography (EEG). The main focus of this study is to decode a paraplegic subject’s motion intentions and provide him with the ability of walking with a lower-body exoskeleton accordingly. We present our novel method of decoding with high offline evaluation accuracies (around 98%), our closed loop implementation structure with considerably short on-site training time (around 38 sec), and preliminary results from the real-time closed loop implementation (NeuroRex) with a paraplegic test subject. PMID:24111008

  8. Polarization-independent optical circulator for high accuracy Faraday depolarization lidar.

    PubMed

    Shiina, Tatsuo; Noguchi, Kazuo; Fukuchi, Tetsuo

    2012-03-01

    A high precision, polarization-independent optical circulator was developed for high accuracy Faraday depolarization lidar. Glan laser prisms and other novel optics were utilized in the circulator optics, resulting in a high extinction ratio of polarization of >30 dB. High accuracy is needed to detect a small rotation angle in the polarization plane of the propagating beam. It is generated by the Faraday effect due to the lightning discharge. The developed circulator delivered high performance of insertion loss and isolation as laser transmitter and echo receiver in the inline lidar optics. PMID:22410893

  9. Next generation dilatometer for highest accuracy thermal expansion measurement of ZERODUR®

    NASA Astrophysics Data System (ADS)

    Jedamzik, Ralf; Engel, Axel; Kunisch, Clemens; Westenberger, Gerhard; Fischer, Peter; Westerhoff, Thomas

    2015-09-01

    In the recent years, the ever tighter tolerance for the Coefficient of thermal expansion (CTE) of IC Lithography component materials is requesting significant progress in the metrology accuracy to determine this property as requested. ZERODUR® is known for its extremely low CTE between 0°C to 50°C. The current measurement of the thermal expansion coefficient is done using push rod dilatometer measurement systems developed at SCHOTT. In recent years measurements have been published showing the excellent CTE homogeneity of ZERODUR® in the one-digit ppb/K range using these systems. The verifiable homogeneity was limited by the CTE(0°C, 50°C) measurement repeatability in the range of ± 1.2 ppb/K of the current improved push rod dilatometer setup using an optical interferometer as detector instead of an inductive coil. With ZERODUR® TAILORED, SCHOTT introduced a low thermal expansion material grade that can be adapted to individual customer application temperature profiles. The basis for this product is a model that has been developed in 2010 for better understanding of the thermal expansion behavior under given temperature versus time conditions. The CTE behavior predicted by the model has proven to be in very good alignment with the data determined in the thermal expansions measurements. The measurements to determine the data feeding the model require a dilatometer setup with excellent stability and accuracy for long measurement times of several days. In the past few years SCHOTT spent a lot of effort to drive a dilatometer measurement technology based on the push rod setup to its limit, to fulfill the continuously demand for higher CTE accuracy and deeper material knowledge of ZERODUR®. This paper reports on the status of the dilatometer technology development at SCHOTT.

  10. Superior accuracy of model-based radiostereometric analysis for measurement of polyethylene wear

    PubMed Central

    Stilling, M.; Kold, S.; de Raedt, S.; Andersen, N. T.; Rahbek, O.; Søballe, K.

    2012-01-01

    Objectives The accuracy and precision of two new methods of model-based radiostereometric analysis (RSA) were hypothesised to be superior to a plain radiograph method in the assessment of polyethylene (PE) wear. Methods A phantom device was constructed to simulate three-dimensional (3D) PE wear. Images were obtained consecutively for each simulated wear position for each modality. Three commercially available packages were evaluated: model-based RSA using laser-scanned cup models (MB-RSA), model-based RSA using computer-generated elementary geometrical shape models (EGS-RSA), and PolyWare. Precision (95% repeatability limits) and accuracy (Root Mean Square Errors) for two-dimensional (2D) and 3D wear measurements were assessed. Results The precision for 2D wear measures was 0.078 mm, 0.102 mm, and 0.076 mm for EGS-RSA, MB-RSA, and PolyWare, respectively. For the 3D wear measures the precision was 0.185 mm, 0.189 mm, and 0.244 mm for EGS-RSA, MB-RSA, and PolyWare respectively. Repeatability was similar for all methods within the same dimension, when compared between 2D and 3D (all p > 0.28). For the 2D RSA methods, accuracy was below 0.055 mm and at least 0.335 mm for PolyWare. For 3D measurements, accuracy was 0.1 mm, 0.2 mm, and 0.3 mm for EGS-RSA, MB-RSA and PolyWare respectively. PolyWare was less accurate compared with RSA methods (p = 0.036). No difference was observed between the RSA methods (p = 0.10). Conclusions For all methods, precision and accuracy were better in 2D, with RSA methods being superior in accuracy. Although less accurate and precise, 3D RSA defines the clinically relevant wear pattern (multidirectional). PolyWare is a good and low-cost alternative to RSA, despite being less accurate and requiring a larger sample size. PMID:23610688

  11. Influence of calibration method and material on the accuracy of stress distribution measurement systems.

    PubMed

    Engel, Karsten; Hartmann, Ulrich; Potthast, Wolfgang; Brüggemann, Gert-Peter

    2016-06-01

    Biomechanical analyses of the stress distribution and the force transfer in the human knee are essential to better understand the aetiology of joint diseases. Accuracy studies of commonly used capacitive or resistive-based stress distribution measurement systems have led to severe problems caused by an inaccurate experimental setup. For instance, in one study, overestimations of the measured forces in the sensor's centre were reported. Therefore, the primary aim of this study was to investigate the ability of capacitive and resistive-based sensors to measure forces in a homogenous pressure environment and the secondary goal was to analyse the influence of different calibration materials on the measurement accuracy. A Novel pressure vessel and metal indenters covered with different rubber materials were used in combination with a material testing machine to load the sensors. Four different linearly increasing nominal forces (925-3670 N) were applied and the deviations between the nominal and the measured forces were calculated. The capacitive measurement system showed errors between 1% and 7% in the homogenous pressure environment, whereas the errors of the resistive system were found to vary between 4% and 17%. The influence of the calibration material was observed to be greater for the resistive sensors (1-179%) than for the capacitive sensors (0.5-25%). In conclusion, it can be stated that - for the pressure measurement systems compared in this article - the capacitive one is less sensitive to the calibration method and the calibration material than the resistive system. PMID:26146092

  12. Accuracy and variability of tumor burden measurement on multi-parametric MRI

    NASA Astrophysics Data System (ADS)

    Salarian, Mehrnoush; Gibson, Eli; Shahedi, Maysam; Gaed, Mena; Gómez, José A.; Moussa, Madeleine; Romagnoli, Cesare; Cool, Derek W.; Bastian-Jordan, Matthew; Chin, Joseph L.; Pautler, Stephen; Bauman, Glenn S.; Ward, Aaron D.

    2014-03-01

    Measurement of prostate tumour volume can inform prognosis and treatment selection, including an assessment of the suitability and feasibility of focal therapy, which can potentially spare patients the deleterious side effects of radical treatment. Prostate biopsy is the clinical standard for diagnosis but provides limited information regarding tumour volume due to sparse tissue sampling. A non-invasive means for accurate determination of tumour burden could be of clinical value and an important step toward reduction of overtreatment. Multi-parametric magnetic resonance imaging (MPMRI) is showing promise for prostate cancer diagnosis. However, the accuracy and inter-observer variability of prostate tumour volume estimation based on separate expert contouring of T2-weighted (T2W), dynamic contrastenhanced (DCE), and diffusion-weighted (DW) MRI sequences acquired using an endorectal coil at 3T is currently unknown. We investigated this question using a histologic reference standard based on a highly accurate MPMRIhistology image registration and a smooth interpolation of planimetric tumour measurements on histology. Our results showed that prostate tumour volumes estimated based on MPMRI consistently overestimated histological reference tumour volumes. The variability of tumour volume estimates across the different pulse sequences exceeded interobserver variability within any sequence. Tumour volume estimates on DCE MRI provided the lowest inter-observer variability and the highest correlation with histology tumour volumes, whereas the apparent diffusion coefficient (ADC) maps provided the lowest volume estimation error. If validated on a larger data set, the observed correlations could support the development of automated prostate tumour volume segmentation algorithms as well as correction schemes for tumour burden estimation on MPMRI.

  13. Accuracy and Validation of Measured and Modeled Data for Distributed PV Interconnection and Control

    SciTech Connect

    Stewart, Emma; Kiliccote, Sila; Arnold, Daniel; von Meier, Alexandra; Arghandeh, R.

    2015-07-27

    The distribution grid is changing to become an active resource with complex modeling needs. The new active distribution grid will, within the next ten years, contain a complex mix of load, generation, storage and automated resources all operating with different objectives on different time scales from each other and requiring detailed analysis. Electrical analysis tools that are used to perform capacity and stability studies have been used for transmission system planning for many years. In these tools, the distribution grid was considered a load and its details and physical components were not modeled. The increase in measured data sources can be utilized for better modeling, but also control of distributed energy resources (DER). The utilization of these sources and advanced modeling tools will require data management, and knowledgeable users. Each of these measurement and modeling devices have accuracy constraints, which will ultimately define their future ability to be planned and controlled. This paper discusses the importance of measured data accuracy for inverter control, interconnection and planning tools and proposes ranges of control accuracy needed to satisfy all concerns based on the present grid infrastructure.

  14. Improving the measurement accuracy of mixed gas by optimizing carbon nanotube sensor's electrode separation

    NASA Astrophysics Data System (ADS)

    Hao, Huimin; Zhang, Yong; Quan, Long

    2015-10-01

    Because of excellent superiorities, triple-electrode carbon nanotube sensor acts good in the detection of multi-component mixed gas. However, as one of the key factors affecting the accuracy of detection, the electrode separation of carbon nanotube gas sensor with triple-electrode structure is very difficult to decide. An optimization method is presented here to improve the mixed gas measurement accuracy. This method optimizes every separation between three electrodes of the carbon nanotube sensors in the sensor array when test the multi-component gas mixture. It collects the ionic current detected by sensor array composed of carbon nanotube sensors with different electrode separations, and creates the kernel partial least square regression (KPLSR) quantitative analysis model of detected gases. The optimum electrode separations come out when the root mean square error of prediction (RMSEP) of test samples reaches the minimum value. The gas mixtures of CO and NO2 are measured using sensor array composed of two carbon nanotube sensor with different electrode separations. And every electrode separation of two sensors is optimized by above-mentioned method. The experimental results show that the proposed method selects the optimal distances between electrodes effectively, and achieves higher measurement accuracy.

  15. Accuracy of flowmeters measuring horizontal groundwater flow in an unconsolidated aquifer simulator.

    USGS Publications Warehouse

    Bayless, E.R.; Mandell, Wayne A.; Ursic, James R.

    2011-01-01

    Borehole flowmeters that measure horizontal flow velocity and direction of groundwater flow are being increasingly applied to a wide variety of environmental problems. This study was carried out to evaluate the measurement accuracy of several types of flowmeters in an unconsolidated aquifer simulator. Flowmeter response to hydraulic gradient, aquifer properties, and well-screen construction was measured during 2003 and 2005 at the U.S. Geological Survey Hydrologic Instrumentation Facility in Bay St. Louis, Mississippi. The flowmeters tested included a commercially available heat-pulse flowmeter, an acoustic Doppler flowmeter, a scanning colloidal borescope flowmeter, and a fluid-conductivity logging system. Results of the study indicated that at least one flowmeter was capable of measuring borehole flow velocity and direction in most simulated conditions. The mean error in direction measurements ranged from 15.1 degrees to 23.5 degrees and the directional accuracy of all tested flowmeters improved with increasing hydraulic gradient. The range of Darcy velocities examined in this study ranged 4.3 to 155 ft/d. For many plots comparing the simulated and measured Darcy velocity, the squared correlation coefficient (r2) exceeded 0.92. The accuracy of velocity measurements varied with well construction and velocity magnitude. The use of horizontal flowmeters in environmental studies appears promising but applications may require more than one type of flowmeter to span the range of conditions encountered in the field. Interpreting flowmeter data from field settings may be complicated by geologic heterogeneity, preferential flow, vertical flow, constricted screen openings, and nonoptimal screen orientation.

  16. Use of Photoelastic Modulators for High-accuracy Spectropolarimetric Imaging of Aerosols

    NASA Technical Reports Server (NTRS)

    Diner, David J.; Davis, Ab; Cunningham, Tom; Gutt, Gary; Hancock, Bruce; Raouf, Nasrat; Wang, Yu; Zan, Jason; Chipman, Russell; Beaudry, Neil; Hirschy, Linda

    2006-01-01

    Passive multiangular, multispectral, and polarimetric sensing approaches each have unique strengths for the measurement of tropospheric aerosol column abundances and microphysical properties. Current spaceborne multispectral and multiangular aerosols sensors operate at approximately 1 km resolution. Under NASA's Instrument Incubator Program, we are developing an electro-optic imaging approach that will enable adding high-accuracy polarimetry to such observations. To achieve a degree of linear polarization (DOLP) uncertainty of 0.5%, our approach temporally modulates the linear-polarization component of incoming light at a rapid rate, enabling each detector within a focal-plane array, combined with polarization analyzers, to measure the relative proportions of the linear Stokes components Q or U to the total intensity. Our system uses tandem photoelastic modulators (PEMs) within a high-reflectance, low diattenuation camera design. The two PEMs vibrate at slightly different resonant frequencies, leading to modulation of the polarized light at a heterodyne frequency of 25 Hz. High-speed (1 kHz) readout of the detector arrays samples the output waveforms from which Q/I and U/I are derived. We report on experimental and theoretical analyses of PEM and optical system performance, along with plans for developing ruggedized PEMs capable of withstanding launch and on-orbit stresses.

  17. High-accuracy global time and frequency transfer with a space-borne hydrogen maser clock

    NASA Technical Reports Server (NTRS)

    Decher, R.; Allan, D. W.; Alley, C. O.; Baugher, C.; Duncan, B. J.; Vessot, R. F. C.; Winkler, G. M. R.

    1983-01-01

    A proposed system for high-accuracy global time and frequency transfer using a hydrogen maser clock in a space vehicle is discussed. Direct frequency transfer with a accuracy of 10 to the minus 14th power and time transfer with an estimated accuracy of 1 nsec are provided by a 3-link microwave system. A short pulse laser system is included for subnanosecond time transfer and system calibration. The results of studies including operational aspects, error sources, data flow, system configuration, and implementation requirements for an initial demonstration experiment using the Space Shuttle are discussed.

  18. Highly charged ions as a basis of optical atomic clockwork of exceptional accuracy.

    PubMed

    Derevianko, Andrei; Dzuba, V A; Flambaum, V V

    2012-11-01

    We propose a novel class of atomic clocks based on highly charged ions. We consider highly forbidden laser-accessible transitions within the 4f(12) ground-state configurations of highly charged ions. Our evaluation of systematic effects demonstrates that these transitions may be used for building exceptionally accurate atomic clocks which may compete in accuracy with recently proposed nuclear clocks. PMID:23215265

  19. The accuracy of three different electronic root canal measuring devices: an in vitro evaluation.

    PubMed

    Tinaz, Ali Cemal; Maden, Murat; Aydin, Cumhur; Türköz, Emin

    2002-06-01

    The main objective of this in vitro study was to evaluate the effects of the operator's experience level and pre-flaring on the accuracy of the results of three different brands of a new generation of root canal measuring devices, as well as the comparison among them. Extracted human teeth were prepared and then actual length and electronic length measurements were made by three different operators according to a double-blind technique. Three different operators performed electronic measurements on each specimen separately with three different electronic root canal measuring devices using in vitro models. Measurements were repeated by all operators after the pre-flaring. Taking the clinical tolerance of +/- 0.5 mm into account, there was no statistically significant difference between the accuracy of the instruments (P > 0.01). However, the results obtained from the Bingo electronic apex locator in pre-flared canals by the beginner operator were statistically significant (P < 0.01). All of the instruments had a clinically acceptable result at the tolerance of +/- 0.5 mm. If the instruments are used in accordance with the manufacturer's instructions, experience with electronic root canal measurement is not essential. However, the operator has to be more careful when working on pre-flared canals. PMID:12227501

  20. Accuracy of a Digital Weight Scale Relative to the Nintendo Wii in Measuring Limb Load Asymmetry

    PubMed Central

    Kumar, NS Senthil; Omar, Baharudin; Joseph, Leonard H; Hamdan, Nor; Htwe, Ohnmar; Hamidun, Nursalbiyah

    2014-01-01

    [Purpose] The aim of the present study was to investigate the accuracy of a digital weight scale relative to the Wii in limb loading measurement during static standing. [Methods] This was a cross-sectional study conducted at a public university teaching hospital. The sample consisted of 24 participants (12 with osteoarthritis and 12 healthy) recruited through convenient sampling. Limb loading measurements were obtained using a digital weight scale and the Nintendo Wii in static standing with three trials under an eyes-open condition. The limb load asymmetry was computed as the symmetry index. [Results] The accuracy of measurement with the digital weight scale relative to the Nintendo Wii was analyzed using the receiver operating characteristic (ROC) curve and Kolmogorov-Smirnov test (K-S test). The area under the ROC curve was found to be 0.67. Logistic regression confirmed the validity of digital weight scale relative to the Nintendo Wii. The D statistics value from the K-S test was found to be 0.16, which confirmed that there was no significant difference in measurement between the equipment. [Conclusion] The digital weight scale is an accurate tool for measuring limb load asymmetry. The low price, easy availability, and maneuverability make it a good potential tool in clinical settings for measuring limb load asymmetry. PMID:25202181

  1. Accuracy of surface tension measurement from drop shapes: the role of image analysis.

    PubMed

    Kalantarian, Ali; Saad, Sameh M I; Neumann, A Wilhelm

    2013-11-01

    Axisymmetric Drop Shape Analysis (ADSA) has been extensively used for surface tension measurement. In essence, ADSA works by matching a theoretical profile of the drop to the extracted experimental profile, taking surface tension as an adjustable parameter. Of the three main building blocks of ADSA, i.e. edge detection, the numerical integration of the Laplace equation for generating theoretical curves and the optimization procedure, only edge detection (that extracts the drop profile line from the drop image) needs extensive study. For the purpose of this article, the numerical integration of the Laplace equation for generating theoretical curves and the optimization procedure will only require a minor effort. It is the aim of this paper to investigate how far the surface tension accuracy of drop shape techniques can be pushed by fine tuning and optimizing edge detection strategies for a given drop image. Two different aspects of edge detection are pursued here: sub-pixel resolution and pixel resolution. The effect of two sub-pixel resolution strategies, i.e. spline and sigmoid, on the accuracy of surface tension measurement is investigated. It is found that the number of pixel points in the fitting procedure of the sub-pixel resolution techniques is crucial, and its value should be determined based on the contrast of the image, i.e. the gray level difference between the drop and the background. On the pixel resolution side, two suitable and reliable edge detectors, i.e. Canny and SUSAN, are explored, and the effect of user-specified parameters of the edge detector on the accuracy of surface tension measurement is scrutinized. Based on the contrast of the image, an optimum value of the user-specified parameter of the edge detector, SUSAN, is suggested. Overall, an accuracy of 0.01mJ/m(2) is achievable for the surface tension determination by careful fine tuning of edge detection algorithms. PMID:24018120

  2. Accuracy of linear measurement using cone-beam computed tomography at different reconstruction angles

    PubMed Central

    Nikneshan, Sima; Aval, Shadi Hamidi; Bakhshalian, Neema; Shahab, Shahriyar; Mohammadpour, Mahdis

    2014-01-01

    Purpose This study was performed to evaluate the effect of changing the orientation of a reconstructed image on the accuracy of linear measurements using cone-beam computed tomography (CBCT). Materials and Methods Forty-two titanium pins were inserted in seven dry sheep mandibles. The length of these pins was measured using a digital caliper with readability of 0.01 mm. Mandibles were radiographed using a CBCT device. When the CBCT images were reconstructed, the orientation of slices was adjusted to parallel (i.e., 0°), +10°, +12°, -12°, and -10° with respect to the occlusal plane. The length of the pins was measured by three radiologists, and the accuracy of these measurements was reported using descriptive statistics and one-way analysis of variance (ANOVA); p<0.05 was considered statistically significant. Results The differences in radiographic measurements ranged from -0.64 to +0.06 at the orientation of -12°, -0.66 to -0.11 at -10°, -0.51 to +0.19 at 0°, -0.64 to +0.08 at +10°, and -0.64 to +0.1 at +12°. The mean absolute values of the errors were greater at negative orientations than at the parallel position or at positive orientations. The observers underestimated most of the variables by 0.5-0.1 mm (83.6%). In the second set of observations, the reproducibility at all orientations was greater than 0.9. Conclusion Changing the slice orientation in the range of -12° to +12° reduced the accuracy of linear measurements obtained using CBCT. However, the error value was smaller than 0.5 mm and was, therefore, clinically acceptable. PMID:25473632

  3. Processing data, for improved, accuracy, from device for measuring speed of sound in a gas

    DOEpatents

    Owen, Thomas E.

    2006-09-19

    A method, used in connection with a pulse-echo type sensor for determining the speed of sound in a gas, for improving the accuracy of speed of sound measurements. The sensor operates on the principle that speed of sound can be derived from the difference between the two-way travel time of signals reflected from two different target faces of the sensor. This time difference is derived by computing the cross correlation between the two reflections. The cross correlation function may be fitted to a parabola whose vertex represents the optimum time coordinate of the coherence peak, thereby providing an accurate measure of the two-way time diffference.

  4. Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

    NASA Astrophysics Data System (ADS)

    Trifkovic, B.; Budak, I.; Todorovic, A.; Hodolic, J.; Puskar, T.; Jevremovic, D.; Vukelic, D.

    2012-01-01

    The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation.

  5. Wound Area Measurement with Digital Planimetry: Improved Accuracy and Precision with Calibration Based on 2 Rulers

    PubMed Central

    Foltynski, Piotr

    2015-01-01

    Introduction In the treatment of chronic wounds the wound surface area change over time is useful parameter in assessment of the applied therapy plan. The more precise the method of wound area measurement the earlier may be identified and changed inappropriate treatment plan. Digital planimetry may be used in wound area measurement and therapy assessment when it is properly used, but the common problem is the camera lens orientation during the taking of a picture. The camera lens axis should be perpendicular to the wound plane, and if it is not, the measured area differ from the true area. Results Current study shows that the use of 2 rulers placed in parallel below and above the wound for the calibration increases on average 3.8 times the precision of area measurement in comparison to the measurement with one ruler used for calibration. The proposed procedure of calibration increases also 4 times accuracy of area measurement. It was also showed that wound area range and camera type do not influence the precision of area measurement with digital planimetry based on two ruler calibration, however the measurements based on smartphone camera were significantly less accurate than these based on D-SLR or compact cameras. Area measurement on flat surface was more precise with the digital planimetry with 2 rulers than performed with the Visitrak device, the Silhouette Mobile device or the AreaMe software-based method. Conclusion The calibration in digital planimetry with using 2 rulers remarkably increases precision and accuracy of measurement and therefore should be recommended instead of calibration based on single ruler. PMID:26252747

  6. A new procedure to measure children's reading speed and accuracy in Italian.

    PubMed

    Morlini, Isabella; Stella, Giacomo; Scorza, Maristella

    2014-02-01

    Impaired readers in primary school should be early recognized, in order to asses a targeted intervention within the school and to start a teaching that respects the difficulties in learning to read, to write and to perform calculations. Screening procedures, inside the primary schools aimed at detecting children with difficulties in reading, are of fundamental importance for guaranteeing an early identification of dyslexic children and reducing both the primary negative effects--on learning--and the secondary negative effects--on the development of the personality--of this disturbance. In this study, we propose a new screening procedure measuring reading speed and accuracy. This procedure is very fast (it is exactly 1 min long), simple, cheap and can be provided by teachers without technical knowledge. On the contrary, most of the currently used diagnostic tests are about 10 min long and must be provided by experts. These two major flaws prevent the widespread use of these tests. On the basis of the results obtained in a survey on about 1500 students attending primary school in Italy, we investigate the relationships between variables used in the screening procedure and variables measuring speed and accuracy in the currently used diagnostic tests in Italy. Then, we analyse the validity of the screening procedure from a statistical point of view, and with an explorative factor analysis, we show that reading speed and accuracy seem to be two separate symptoms of the dyslexia phenomenon. PMID:24115526

  7. Measurement methods and accuracy analysis of Chang'E-5 Panoramic Camera installation parameters

    NASA Astrophysics Data System (ADS)

    Yan, Wei; Ren, Xin; Liu, Jianjun; Tan, Xu; Wang, Wenrui; Chen, Wangli; Zhang, Xiaoxia; Li, Chunlai

    2016-04-01

    Chang'E-5 (CE-5) is a lunar probe for the third phase of China Lunar Exploration Project (CLEP), whose main scientific objectives are to implement lunar surface sampling and to return the samples back to the Earth. To achieve these goals, investigation of lunar surface topography and geological structure within sampling area seems to be extremely important. The Panoramic Camera (PCAM) is one of the payloads mounted on CE-5 lander. It consists of two optical systems which installed on a camera rotating platform. Optical images of sampling area can be obtained by PCAM in the form of a two-dimensional image and a stereo images pair can be formed by left and right PCAM images. Then lunar terrain can be reconstructed based on photogrammetry. Installation parameters of PCAM with respect to CE-5 lander are critical for the calculation of exterior orientation elements (EO) of PCAM images, which is used for lunar terrain reconstruction. In this paper, types of PCAM installation parameters and coordinate systems involved are defined. Measurement methods combining camera images and optical coordinate observations are studied for this work. Then research contents such as observation program and specific solution methods of installation parameters are introduced. Parametric solution accuracy is analyzed according to observations obtained by PCAM scientifically validated experiment, which is used to test the authenticity of PCAM detection process, ground data processing methods, product quality and so on. Analysis results show that the accuracy of the installation parameters affects the positional accuracy of corresponding image points of PCAM stereo images within 1 pixel. So the measurement methods and parameter accuracy studied in this paper meet the needs of engineering and scientific applications. Keywords: Chang'E-5 Mission; Panoramic Camera; Installation Parameters; Total Station; Coordinate Conversion

  8. Mass Accuracy and Isotopic Abundance Measurements for HR-MS Instrumentation: Capabilities for Non-Targeted Analyses

    NASA Astrophysics Data System (ADS)

    Knolhoff, Ann M.; Callahan, John H.; Croley, Timothy R.

    2014-07-01

    The development of automated non-targeted workflows for small molecule analyses is highly desirable in many areas of research and diagnostics. Sufficient mass and chromatographic resolution is necessary for the detectability of compounds and subsequent componentization and interpretation of ions. The mass accuracy and relative isotopic abundance are critical in correct molecular formulae generation for unknown compounds. While high-resolution instrumentation provides accurate mass information, sample complexity can greatly influence data quality and the measurement of compounds of interest. Two high-resolution instruments, an Orbitrap and a Q-TOF, were evaluated for mass accuracy and relative isotopic abundance with various concentrations of a standard mixture in four complex sample matrices. The overall average ± standard deviation of the mass accuracy was 1.06 ± 0.76 ppm and 1.62 ± 1.88 ppm for the Orbitrap and the Q-TOF, respectively; however, individual measurements were ± 5 ppm for the Orbitrap and greater than 10 ppm for the Q-TOF. Relative isotopic abundance measurements for A + 1 were within 5% of the theoretical value if the intensity of the monoisotopic peak was greater than 1E7 for the Orbitrap and 1E5 for the Q-TOF, where an increase in error is observed with a decrease in intensity. Furthermore, complicating factors were found in the data that would impact automated data analysis strategies, including coeluting species that interfere with detectability and relative isotopic abundance measurements. The implications of these findings will be discussed with an emphasis on reasonable expectations from these instruments, guidelines for experimental workflows, data analysis considerations, and software design for non-targeted analyses.

  9. Mass accuracy and isotopic abundance measurements for HR-MS instrumentation: capabilities for non-targeted analyses.

    PubMed

    Knolhoff, Ann M; Callahan, John H; Croley, Timothy R

    2014-07-01

    The development of automated non-targeted workflows for small molecule analyses is highly desirable in many areas of research and diagnostics. Sufficient mass and chromatographic resolution is necessary for the detectability of compounds and subsequent componentization and interpretation of ions. The mass accuracy and relative isotopic abundance are critical in correct molecular formulae generation for unknown compounds. While high-resolution instrumentation provides accurate mass information, sample complexity can greatly influence data quality and the measurement of compounds of interest. Two high-resolution instruments, an Orbitrap and a Q-TOF, were evaluated for mass accuracy and relative isotopic abundance with various concentrations of a standard mixture in four complex sample matrices. The overall average ± standard deviation of the mass accuracy was 1.06 ± 0.76 ppm and 1.62 ± 1.88 ppm for the Orbitrap and the Q-TOF, respectively; however, individual measurements were ± 5 ppm for the Orbitrap and greater than 10 ppm for the Q-TOF. Relative isotopic abundance measurements for A + 1 were within 5% of the theoretical value if the intensity of the monoisotopic peak was greater than 1E7 for the Orbitrap and 1E5 for the Q-TOF, where an increase in error is observed with a decrease in intensity. Furthermore, complicating factors were found in the data that would impact automated data analysis strategies, including coeluting species that interfere with detectability and relative isotopic abundance measurements. The implications of these findings will be discussed with an emphasis on reasonable expectations from these instruments, guidelines for experimental workflows, data analysis considerations, and software design for non-targeted analyses. PMID:24729191

  10. Craniofacial skeletal measurements based on computed tomography: Part I. Accuracy and reproducibility.

    PubMed

    Waitzman, A A; Posnick, J C; Armstrong, D C; Pron, G E

    1992-03-01

    Computed tomography (CT) is a useful modality for the management of craniofacial anomalies. A study was undertaken to assess whether CT measurements of the upper craniofacial skeleton accurately represent the bony region imaged. Measurements taken directly from five dry skulls (approximate ages: adults, over 18 years; child, 4 years; infant, 6 months) were compared to those from axial CT scans of these skulls. Excellent agreement was found between the direct (dry skull) and indirect (CT) measurements. The effect of head tilt on the accuracy of these measurements was investigated. The error was within clinically acceptable limits (less than 5 percent) if the angle was no more than +/- 4 degrees from baseline (0 degrees). Objective standardized information gained from CT should complement the subjective clinical data usually collected for the treatment of craniofacial deformities. PMID:1571344

  11. High-accuracy Multiangle Spectropolarimetric Imaging Concept for Aerosol Remote Sensing from Space

    NASA Astrophysics Data System (ADS)

    Diner, D. J.; Chipman, R. A.; Cairns, B.; Foo, L. D.; Keller, C. U.; Macenka, S. A.; Bruce, C. F.

    2004-05-01

    Satellite remote sensing has a key role in measuring the distribution, radiative impact, and regional and global spatial context of tropospheric aerosols. A synergistic combination of multispectral, multiangle, and polarimetric approaches would improve the accuracies of aerosol optical depth and particle property characterizations compared to what is achievable using each method by itself. In this paper we discuss the science benefits and technical feasibility of combining key attributes of multiple aerosol remote sensing instruments into a single instrument package. The features of the conceptual instrument are: spectral coverage from the near-UV to the shortwave infrared; global coverage within a few days; intensity and polarimetric imaging simultaneously at multiple view angles; kilometer to sub-kilometer spatial resolution; and measurement of the degree of linear polarization in one visible and one shortwave-infrared spectral band, i.e., a subset of the full spectral complement, with an uncertainty of 0.5% or less. The polarimetric accuracy is the driving requirement of the instrument design, and is stipulated in order to achieve uncertainty goals in optical depth (0.01) and single scattering albedo (0.03) that appear difficult to reach given the current state-of-the-art of the calibration of intensity-only measurements. Bispectral polarimetry is invoked to enable size-resolved retrievals of particle real refractive index. After examining many approaches and technologies for imaging polarimetry, we conclude that ultrafast time-multiplexing is the best option for meeting the instrument performance requirements. The approach is based upon innovative advances in high-precision imaging polarimetry developed for ground-based solar astronomy. Rapid modulation of the linear polarization Stokes components Q and U, coupled with synchronous demodulation in a charge-caching focal plane, provides two essential benefits: (1) the same detector is used to measure the relative

  12. Accuracy of hands v. household measures as portion size estimation aids.

    PubMed

    Gibson, Alice A; Hsu, Michelle S H; Rangan, Anna M; Seimon, Radhika V; Lee, Crystal M Y; Das, Arpita; Finch, Charles H; Sainsbury, Amanda

    2016-01-01

    Accurate estimation of food portion size is critical in dietary studies. Hands are potentially useful as portion size estimation aids; however, their accuracy has not been tested. The aim of the present study was to test the accuracy of a novel portion size estimation method using the width of the fingers as a 'ruler' to measure the dimensions of foods ('finger width method'), as well as fists and thumb or finger tips. These hand measures were also compared with household measures (cups and spoons). A total of sixty-seven participants (70 % female; age 32·7 (sd 13·7) years; BMI 23·2 (sd  3·5) kg/m(2)) attended a 1·5 h session in which they estimated the portion sizes of forty-two pre-weighed foods and liquids. Hand measurements were used in conjunction with geometric formulas to convert estimations to volumes. Volumes determined with hand and household methods were converted to estimated weights using density factors. Estimated weights were compared with true weights, and the percentage difference from the true weight was used to compare accuracy between the hand and household methods. Of geometrically shaped foods and liquids estimated with the finger width method, 80 % were within ±25 % of the true weight of the food, and 13 % were within ±10 %, in contrast to 29 % of those estimated with the household method being within ±25 % of the true weight of the food, and 8 % being within ±10 %. For foods that closely resemble a geometric shape, the finger width method provides a novel and acceptably accurate method of estimating portion size. PMID:27547392

  13. Influence of electrode positioning on accuracy and reproducibility of electrical velocimetry cardiac output measurements.

    PubMed

    Trinkmann, Frederik; Berger, Manuel; Michels, Julia D; Doesch, Christina; Weiss, Christel; Schoenberg, Stefan O; Akin, Ibrahim; Borggrefe, Martin; Papavassiliu, Theano; Saur, Joachim

    2016-09-01

    Electrical velocimetry (EV) is one of the most recent adaptions of impedance cardiography. Previous studies yielded diverging results identifying several factors negatively influencing accuracy. Although electrode arrangement is suspected to be an influencing factor for impedance cardiography in general, no data for EV is available. We aimed to prospectively assess the influence of electrode position on the accuracy and reproducibility of cardiac output (CO) measurements obtained by EV. Two pairs of standard electrocardiographic electrodes were placed at predefined positions of the thorax in 81 patients. The inter-electrode gap was varied between either 5 or 15 cm by caudal movement of the lowest electrode. Measurements were averaged over 20 s and performed twice at each electrode position. Reference values were determined using cardiac magnetic resonance imaging (CMR). Mean bias was 1.2  ±  1.6 l min(-1) (percentage error 22  ±  28%) between COCMR and COEV at the 5 cm gap significantly improving to 0.5  ±  1.6 l min(-1) (8  ±  28%) when increasing the gap (p  <  0.0001). The mean difference between repeated measurements was 0.0  ±  0.3 l min(-1) for the 5 cm and 0.1  ±  0.3 l min(-1) for the 15 cm gap, respectively (p  =  0.3). The accuracy of EV can be significantly improved when increasing the lower inter-electrode gap still exceeding the Critchley and Critchley recommendations. Therefore, absolute values should not be used interchangeably in clinical routine. As the reproducibility was not negatively affected, serial hemodynamic measurements can be reliably acquired in stable patients when the electrode position remains unchanged. PMID:27480359

  14. Evaluating the accuracy of tooth color measurement by combining the Munsell color system and dental colorimeter.

    PubMed

    Chang, Jiun-Yao; Chen, Wen-Cheng; Huang, Ta-Ko; Wang, Jen-Chyan; Fu, Po-Sung; Chen, Jeng-Huey; Hung, Chun-Cheng

    2012-09-01

    As we pay increasing attention to dental aesthetics, tooth color matching has become an important part of daily dental practice. This aim of this study was to develop a method to enhance the accuracy of a tooth color matching machine. The Munsell color tabs in the range of natural human teeth were measured using a tooth color measuring machine (ShadeEye NCC). The machine's accuracy was analyzed using an analysis of variance test and a Tukey post-hoc test. When matching the Munsell color tabs with the ShadeEye NCC colorimeter, settings of Chroma greater than 6 and Value less than 4 showed unacceptable clinical results. When the CIELAB mode was used, the a* value (which represents the red-green axis in the Commission Internationale de l'Eclairage color space) made no significant difference (p=0.84), the L* value (which represents the lightness) resulted in a negative correlation, and the b* value (which represents the yellow-blue axis) resulted in a positive correlation with ΔE. When the Munsell color tabs and the Vitapan were measured in the same mode and compared, the inaccuracies showed that the Vitapan was not a proper tool for evaluating the stability and accuracy of ShadeEye NCC. By knowing the limitations of the machine, we evaluated the data using the Munsell color tabs; shade beyond the acceptable range should be reevaluated using a visual shade matching method, or if measured by another machine, this shade range should be covered to obtain more accurate results. PMID:22974668

  15. A measurement technique to determine the calibration accuracy of an electromagnetic tracking system to radiation isocenter

    SciTech Connect

    Litzenberg, Dale W.; Gallagher, Ian; Masi, Kathryn J.; Lee, Choonik; Prisciandaro, Joann I.; Hamstra, Daniel A.; Ritter, Timothy; Lam, Kwok L.

    2013-08-15

    Purpose: To present and characterize a measurement technique to quantify the calibration accuracy of an electromagnetic tracking system to radiation isocenter.Methods: This technique was developed as a quality assurance method for electromagnetic tracking systems used in a multi-institutional clinical hypofractionated prostate study. In this technique, the electromagnetic tracking system is calibrated to isocenter with the manufacturers recommended technique, using laser-based alignment. A test patient is created with a transponder at isocenter whose position is measured electromagnetically. Four portal images of the transponder are taken with collimator rotations of 45° 135°, 225°, and 315°, at each of four gantry angles (0°, 90°, 180°, 270°) using a 3 × 6 cm{sup 2} radiation field. In each image, the center of the copper-wrapped iron core of the transponder is determined. All measurements are made relative to this transponder position to remove gantry and imager sag effects. For each of the 16 images, the 50% collimation edges are identified and used to find a ray representing the rotational axis of each collimation edge. The 16 collimator rotation rays from four gantry angles pass through and bound the radiation isocenter volume. The center of the bounded region, relative to the transponder, is calculated and then transformed to tracking system coordinates using the transponder position, allowing the tracking system's calibration offset from radiation isocenter to be found. All image analysis and calculations are automated with inhouse software for user-independent accuracy. Three different tracking systems at two different sites were evaluated for this study.Results: The magnitude of the calibration offset was always less than the manufacturer's stated accuracy of 0.2 cm using their standard clinical calibration procedure, and ranged from 0.014 to 0.175 cm. On three systems in clinical use, the magnitude of the offset was found to be 0.053 ± 0.036, 0

  16. Nonsinusoidal electrical measurement accuracy in adjustable-speed motors and drives

    SciTech Connect

    Domijan, A.; Czarkowski, D.; Johnson, J.H.

    1998-11-01

    Accurate measurements of voltage, current, and power under nonsinusoidal conditions are essential for determining the efficiency of a drive system and performing separation of losses between an adjustable-speed drive (ASD) and an electric motor. That information is invaluable for equipment designers, manufacturers, and users. Three modern power meters and analyzers were tested to determine their accuracy with various nonsinusoidal waveforms applied. The meters were subjected to waveforms that are characteristic to the three most common fractional and integral horsepower ASD technologies, namely, pulsewidth modulation induction, brushless dc, and switched-reluctance drives. The tests were performed under field conditions and in a computer-controlled laboratory environment. The obtained results show that some meters are able to measure accurately electric power at the input to ASD`s. However, the output power of ASD`s for brushless dc and switched-reluctance technology was not measured with acceptable accuracy by any of the tested meters. Possible reasons of meters inaccuracies and suggestions for performance improvement are presented. Conclusions on the present state of ASD electric power measurements and recommendations for further research are given.

  17. A Novel Method for Assessing the Accuracies of In Situ Measurements of Water Vapor in the UT/LS

    NASA Astrophysics Data System (ADS)

    Toohey, D.; Avallone, L.; Ross, M.

    2008-12-01

    We report on results from a series of flights of the NASA WB57F Aircraft into the exhaust plumes of rockets as part of the Plume Ultrafast Measurements Aquisition (PUMA) campaign. It is found that the emission ratio of vapor vapor to CO2, along with highly accurate measurements of CO2 can be used to constrain the abundances of H2O in the plume, such that the highly linear correlation between these two species can be used to determine the accuracies of total H2O measurements in the very dry upper troposphere and lowermost stratosphere. In addition, as the plume disperses evaporation of ice provides a fundamental thermodynamic constraint on water vapor abundances that is an independent test of instrument response. These plume observations provide a unique in situ, flight-based test of instruments to a level of accuracy that is very likely not possible in other types of measurement programs, such as in-flight intercomparisons or comprehensive laboratory calibrations. We propose a low-cost program focusing on flights through plumes of rockets and aircraft in the UT/LS that could resolve the longstanding disagreements between different in situ water vapor instruments.

  18. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... recording at intervals not to exceed 5 minutes. (4) Flow measurement adaptor (40 CFR part 50, appendix L.... (7) Teflon sample filter, as specified in section 6 of 40 CFR part 50, appendix L (if required). (d... intervals not to exceed 5 minutes. (3) Barometer, range 600 mm Hg to 800 mm Hg, certified accurate to 2...

  19. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... recording at intervals not to exceed 5 minutes. (4) Flow measurement adaptor (40 CFR part 50, appendix L.... (7) Teflon sample filter, as specified in section 6 of 40 CFR part 50, appendix L (if required). (d... intervals not to exceed 5 minutes. (3) Barometer, range 600 mm Hg to 800 mm Hg, certified accurate to 2...

  20. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... recording at intervals not to exceed 5 minutes. (4) Flow measurement adaptor (40 CFR part 50, appendix L.... (7) Teflon sample filter, as specified in section 6 of 40 CFR part 50, appendix L (if required). (d... intervals not to exceed 5 minutes. (3) Barometer, range 600 mm Hg to 800 mm Hg, certified accurate to 2...

  1. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... recording at intervals not to exceed 5 minutes. (4) Flow measurement adaptor (40 CFR part 50, appendix L.... (7) Teflon sample filter, as specified in section 6 of 40 CFR part 50, appendix L (if required). (d... intervals not to exceed 5 minutes. (3) Barometer, range 600 mm Hg to 800 mm Hg, certified accurate to 2...

  2. Cell Tracking Accuracy Measurement Based on Comparison of Acyclic Oriented Graphs.

    PubMed

    Matula, Pavel; Maška, Martin; Sorokin, Dmitry V; Matula, Petr; Ortiz-de-Solórzano, Carlos; Kozubek, Michal

    2015-01-01

    Tracking motile cells in time-lapse series is challenging and is required in many biomedical applications. Cell tracks can be mathematically represented as acyclic oriented graphs. Their vertices describe the spatio-temporal locations of individual cells, whereas the edges represent temporal relationships between them. Such a representation maintains the knowledge of all important cellular events within a captured field of view, such as migration, division, death, and transit through the field of view. The increasing number of cell tracking algorithms calls for comparison of their performance. However, the lack of a standardized cell tracking accuracy measure makes the comparison impracticable. This paper defines and evaluates an accuracy measure for objective and systematic benchmarking of cell tracking algorithms. The measure assumes the existence of a ground-truth reference, and assesses how difficult it is to transform a computed graph into the reference one. The difficulty is measured as a weighted sum of the lowest number of graph operations, such as split, delete, and add a vertex and delete, add, and alter the semantics of an edge, needed to make the graphs identical. The measure behavior is extensively analyzed based on the tracking results provided by the participants of the first Cell Tracking Challenge hosted by the 2013 IEEE International Symposium on Biomedical Imaging. We demonstrate the robustness and stability of the measure against small changes in the choice of weights for diverse cell tracking algorithms and fluorescence microscopy datasets. As the measure penalizes all possible errors in the tracking results and is easy to compute, it may especially help developers and analysts to tune their algorithms according to their needs. PMID:26683608

  3. Cell Tracking Accuracy Measurement Based on Comparison of Acyclic Oriented Graphs

    PubMed Central

    Sorokin, Dmitry V.; Matula, Petr; Ortiz-de-Solórzano, Carlos; Kozubek, Michal

    2015-01-01

    Tracking motile cells in time-lapse series is challenging and is required in many biomedical applications. Cell tracks can be mathematically represented as acyclic oriented graphs. Their vertices describe the spatio-temporal locations of individual cells, whereas the edges represent temporal relationships between them. Such a representation maintains the knowledge of all important cellular events within a captured field of view, such as migration, division, death, and transit through the field of view. The increasing number of cell tracking algorithms calls for comparison of their performance. However, the lack of a standardized cell tracking accuracy measure makes the comparison impracticable. This paper defines and evaluates an accuracy measure for objective and systematic benchmarking of cell tracking algorithms. The measure assumes the existence of a ground-truth reference, and assesses how difficult it is to transform a computed graph into the reference one. The difficulty is measured as a weighted sum of the lowest number of graph operations, such as split, delete, and add a vertex and delete, add, and alter the semantics of an edge, needed to make the graphs identical. The measure behavior is extensively analyzed based on the tracking results provided by the participants of the first Cell Tracking Challenge hosted by the 2013 IEEE International Symposium on Biomedical Imaging. We demonstrate the robustness and stability of the measure against small changes in the choice of weights for diverse cell tracking algorithms and fluorescence microscopy datasets. As the measure penalizes all possible errors in the tracking results and is easy to compute, it may especially help developers and analysts to tune their algorithms according to their needs. PMID:26683608

  4. Electron Microprobe Analysis of Hf in Zircon: Suggestions for Improved Accuracy of a Difficult Measurement

    NASA Astrophysics Data System (ADS)

    Fournelle, J.; Hanchar, J. M.

    2013-12-01

    It is not commonly recognized as such, but the accurate measurement of Hf in zircon is not a trivial analytical issue. This is important to assess because Hf is often used as an internal standard for trace element analyses of zircon by LA-ICPMS. The issues pertaining to accuracy revolve around: (1) whether the Hf Ma or the La line is used; (2) what accelerating voltage is applied if Zr La is also measured, and (3) what standard for Hf is used. Weidenbach, et al.'s (2004) study of the 91500 zircon demonstrated the spread (in accuracy) of possible EPMA values for six EPMA labs, 2 of which used Hf Ma, 3 used Hf La, and one used Hf Lb, and standards ranged from HfO2, a ZrO2-HfO2 compound, Hf metal, and hafnon. Weidenbach, et al., used the ID-TIMS values as the correct value (0.695 wt.% Hf.), for which not one of the EPMA labs came close to that value (3 were low and 3 were high). Those data suggest: (1) that there is a systematic underestimation error of the 0.695 wt% Hf (ID-TIMS Hf) value if Hf Ma is used; most likely an issue with the matrix correction, as the analytical lines and absorption edges of Zr La, Si Ka and Hf Ma are rather tightly packed in the electromagnetic spectrum. Mass absorption coefficients are easily in error (e.g., Donovan's determination of the MAC of Hf by Si Ka of 5061 differs from the typically used Henke value of 5449 (Donovan et al, 2002); and (2) For utilization of the Hf La line, however, the second order Zr Ka line interferes with Hf La if the accelerating voltage is greater than 17.99 keV. If this higher keV is used and differential mode PHA is applied, only a portion of the interference is removed (e.g., removal of escape peaks), causing an overestimation of Hf content. Unfortunately, it is virtually impossible to apply an interference correction in this case, as it is impossible to locate Hf-free Zr probe standard. We have examined many of the combinations used by those six EPMA labs and concluded that the optimal EPMA is done with Hf

  5. A Design of Experiments (DOE) approach to optimise temperature measurement accuracy in Solid Oxide Fuel Cell (SOFC)

    NASA Astrophysics Data System (ADS)

    Barari, F.; Morgan, R.; Barnard, P.

    2014-11-01

    In SOFC, accurately measuring the hot-gas temperature is challenging due to low gas velocity, high wall temperature, complex flow geometries and relatively small pipe diameter. Improper use of low cost thermometry system such as standard Type K thermocouples (TC) may introduce large measurement error. The error could have a negative effect on the thermal management of the SOFC systems and consequential reduction in efficiency. In order to study the factors affecting the accuracy of the temperature measurement system, a mathematical model of a TC inside a pipe was defined and numerically solved. The model calculated the difference between the actual and the measured gas temperature inside the pipe. A statistical Design of Experiment (DOE) approach was applied to the modelling data to compute the interaction effect between variables and investigate the significance of each variable on the measurement errors. In this study a full factorial DOE design with six variables (wall temperature, gas temperature, TC length, TC diameter and TC emissivity) at two levels was carried out. Four different scenarios, two sets of TC length (6 - 10.5 mm and 17 - 22 mm) and two different sets of temperature range (550 - 650 °C and 750 - 850 °C), were proposed. DOE analysis was done for each scenario and results were compared to identify key parameters affecting the accuracy of a particular temperature reading.

  6. Oxygenator Safety Evaluation: A Focus on Connection Grip Strength and Arterial Temperature Measurement Accuracy

    PubMed Central

    Newland, Richard F.; Baker, Robert A.; Sanderson, Andrew J.; Tuble, Sigrid C.; Tully, Phil J.

    2012-01-01

    Abstract: This report describes the assessment of three specific safety-related specifications in the consideration of an alternate oxygenator; first the grip strength relationship between various oxygenator connectors and SMARxT® tubing, second, the grip strength of various biopassive tubings and an isolated SMARxT® connector, and finally, the accuracy of the arterial outlet temperature measurement. Grip strength experiments for the connections between the SMARxT® tubing and the venous reservoir outlet and the oxygenator venous inlet and oxygenator arterial outlet of the Medtronic Affinity®, Sorin Synthesis®, Sorin Primox®, and Terumo Capiox® RX25 oxygenators were performed. In addition we compared the grip strength of polyvinyl chloride, Physio®, Trillium®, Carmeda®, X-Coating®, and SMARxT® tubing. The accuracy of the integrated arterial outlet temperature probes was determined by comparing the temperatures measured by the integrated probe with a precision reference thermometer. Connector grip strength comparisons for the evaluation oxygenators with SMARxT® tubing showed significant variation between oxygenators and connections (p = .02). Evaluation of the arterial outlet showed significant variation between evaluation oxygenators, while at the venous reservoir outlet and oxygenator inlet, there were no significant differences. Grip strength comparison data for the various tubing types demonstrated a main effect for tubing type F(5, 18) = 8.01, p = .002, ηp2 = .77. Temperature accuracy measurements demonstrated that all oxygenators overread the arterial outlet temperature at 15°C, whilst at temperatures ≥25°C, all oxygenators underread the arterial outlet temperature. The integrity of SMARxT® tubing connection is influenced by the connector type, and may decline over time, highlighting the importance to not consider interchanging components of the bypass circuit as inconsequential. PMID:22893983

  7. Computer-aided analysis of star shot films for high-accuracy radiation therapy treatment units

    NASA Astrophysics Data System (ADS)

    Depuydt, Tom; Penne, Rudi; Verellen, Dirk; Hrbacek, Jan; Lang, Stephanie; Leysen, Katrien; Vandevondel, Iwein; Poels, Kenneth; Reynders, Truus; Gevaert, Thierry; Duchateau, Michael; Tournel, Koen; Boussaer, Marlies; Cosentino, Dorian; Garibaldi, Cristina; Solberg, Timothy; De Ridder, Mark

    2012-05-01

    As mechanical stability of radiation therapy treatment devices has gone beyond sub-millimeter levels, there is a rising demand for simple yet highly accurate measurement techniques to support the routine quality control of these devices. A combination of using high-resolution radiosensitive film and computer-aided analysis could provide an answer. One generally known technique is the acquisition of star shot films to determine the mechanical stability of rotations of gantries and the therapeutic beam. With computer-aided analysis, mechanical performance can be quantified as a radiation isocenter radius size. In this work, computer-aided analysis of star shot film is further refined by applying an analytical solution for the smallest intersecting circle problem, in contrast to the gradient optimization approaches used until today. An algorithm is presented and subjected to a performance test using two different types of radiosensitive film, the Kodak EDR2 radiographic film and the ISP EBT2 radiochromic film. Artificial star shots with a priori known radiation isocenter size are used to determine the systematic errors introduced by the digitization of the film and the computer analysis. The estimated uncertainty on the isocenter size measurement with the presented technique was 0.04 mm (2σ) and 0.06 mm (2σ) for radiographic and radiochromic films, respectively. As an application of the technique, a study was conducted to compare the mechanical stability of O-ring gantry systems with C-arm-based gantries. In total ten systems of five different institutions were included in this study and star shots were acquired for gantry, collimator, ring, couch rotations and gantry wobble. It was not possible to draw general conclusions about differences in mechanical performance between O-ring and C-arm gantry systems, mainly due to differences in the beam-MLC alignment procedure accuracy. Nevertheless, the best performing O-ring system in this study, a BrainLab/MHI Vero system

  8. Portable oil bath for high-accuracy resistance transfer and maintenance

    NASA Astrophysics Data System (ADS)

    Shiota, Fuyuhiko

    1999-10-01

    A portable oil bath containing one standard resistor for high-accuracy resistance transfer and maintenance was developed and operated for seven years in the National Research Laboratory of Metrology. The aim of the bath is to save labor and apparatus for high-accuracy resistance transfer and maintenance by consistently keeping the standard resistor in an optimum environmental condition. The details of the prototype system, including its performance, are described together with some suggestions for a more practical bath design, which adopts the same concept.

  9. Flavor identification of astronomical high energy neutrinos and the accuracy of mixing angles

    SciTech Connect

    Hwang, Ggyoung-Riun; Siyeon, Kim

    2008-11-23

    Typical initial neutrino fluxes from pion decays may be different depending on energy, since the muon decays can be excluded due to the electromagnetic energy loss. However, the specification of the initial flux ratio is limited by the accuracy of neutrino mixing parameters. We will discuss the expected measurement of relative flavors at future neutrino telescopes, focusing on the ambiguity in current neutrino parameters.

  10. Evaluation of electrical impedance ratio measurements in accuracy of electronic apex locators

    PubMed Central

    Kim, Pil-Jong; Kim, Hong-Gee

    2015-01-01

    Objectives The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). Materials and Methods The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. Results Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. Conclusions Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC. PMID:25984472

  11. RapidEye constellation relative radiometric accuracy measurement using lunar images

    NASA Astrophysics Data System (ADS)

    Steyn, Joe; Tyc, George; Beckett, Keith; Hashida, Yoshi

    2009-09-01

    The RapidEye constellation includes five identical satellites in Low Earth Orbit (LEO). Each satellite has a 5-band (blue, green, red, red-edge and near infrared (NIR)) multispectral imager at 6.5m GSD. A three-axes attitude control system allows pointing the imager of each satellite at the Moon during lunations. It is therefore possible to image the Moon from near identical viewing geometry within a span of 80 minutes with each one of the imagers. Comparing the radiometrically corrected images obtained from each band and each satellite allows a near instantaneous relative radiometric accuracy measurement and determination of relative gain changes between the five imagers. A more traditional terrestrial vicarious radiometric calibration program has also been completed by MDA on RapidEye. The two components of this program provide for spatial radiometric calibration ensuring that detector-to-detector response remains flat, while a temporal radiometric calibration approach has accumulated images of specific dry dessert calibration sites. These images are used to measure the constellation relative radiometric response and make on-ground gain and offset adjustments in order to maintain the relative accuracy of the constellation within +/-2.5%. A quantitative comparison between the gain changes measured by the lunar method and the terrestrial temporal radiometric calibration method is performed and will be presented.

  12. Optimizing stepwise rotation of dodecahedron sound source to improve the accuracy of room acoustic measures.

    PubMed

    Martellotta, Francesco

    2013-09-01

    Dodecahedron sound sources are widely used for acoustical measurement purposes as they produce a good approximation of omnidirectional radiation. Evidence shows that such an assumption is acceptable only in the low-frequency range (namely below 1 kHz), while at higher frequencies sound radiation is far from being uniform. In order to improve the accuracy of acoustical measurements obtained from dodecahedron sources, international standard ISO 3382 suggests an averaging of results after a source rotation. This paper investigates the effects of such rotations, both in terms of variations in acoustical parameters and spatial distribution of sound reflections. Taking advantage of a spherical microphone array, the different reflection patterns were mapped as a function of source rotation, showing that some reflections may be considerably attenuated for different aiming directions. This paper investigates the concept of averaging results while changing rotation angles and the minimum number of rotations required to improve the accuracy of the average value. Results show that averages of three measurements carried out at 30° angular steps are closer to actual values and show much less fluctuation. In addition, an averaging of the directional intensity components of the selected responses stabilizes the spatial distribution of the reflections. PMID:23967936

  13. Accuracy of Raman lidar water vapor calibration and its applicability to long-term measurements.

    PubMed

    Leblanc, Thierry; McDermid, I Stuart

    2008-10-20

    A Raman lidar calibration method adapted to the long-term monitoring of atmospheric water vapor is proposed. The accuracy of Raman lidar water vapor profiles is limited by that of the calibration process. Typically, calibration using in situ balloon-borne measurements suffers from the nonsimultaneity and noncollocation of the lidar and in situ measurements, while calibration from passive remote sensors suffers from the lower accuracy of the retrievals and incomplete sampling of the water vapor column observed by lidar. We propose a new hybrid calibration method using a combination of absolute calibration from radiosonde campaigns and routine-basis (off-campaign) partial calibration using a standard lamp. This new method takes advantage of the stability of traceable calibrated lamps as reliable sources of known spectral irradiance combined with the best available in situ measurements. An integrated approach is formulated, which can be used for the future long-term monitoring of water vapor by Raman lidars within the international Network for the Detection of Atmospheric Composition Change and other networks. PMID:18936807

  14. An analysis of the accuracy of magnetic resonance flip angle measurement methods

    NASA Astrophysics Data System (ADS)

    Morrell, Glen R.; Schabel, Matthias C.

    2010-10-01

    Several methods of flip angle mapping for magnetic resonance imaging have been proposed. We evaluated the accuracy of five methods of flip angle measurement in the presence of measurement noise. Our analysis was performed in a closed form by propagation of probability density functions (PDFs). The flip angle mapping methods compared were (1) the phase-sensitive method, (2) the dual-angle method using gradient recalled echoes (GRE), (3) an extended version of the GRE dual-angle method incorporating phase information, (4) the AFI method and (5) an extended version of the AFI method incorporating phase information. Our analysis took into account differences in required imaging time for these methods in the comparison of noise efficiency. PDFs of the flip angle estimate for each method for each value of true flip angle were calculated. These PDFs completely characterize the performance of each method. Mean bias and standard deviation were computed from these PDFs to more simply quantify the relative accuracy of each method over its range of measurable flip angles. We demonstrate that the phase-sensitive method provides the lowest mean bias and standard deviation of flip angle estimate of the five methods evaluated over a wide range of flip angles.

  15. Relative accuracy evaluation.

    PubMed

    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

  16. 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

  17. HEAT: High accuracy extrapolated ab initio thermochemistry. III. Additional improvements and overview.

    SciTech Connect

    Harding, M. E.; Vazquez, J.; Ruscic, B.; Wilson, A. K.; Gauss, J.; Stanton, J. F.; Chemical Sciences and Engineering Division; Univ. t Mainz; The Univ. of Texas; Univ. of North Texas

    2008-01-01

    Effects of increased basis-set size as well as a correlated treatment of the diagonal Born-Oppenheimer approximation are studied within the context of the high-accuracy extrapolated ab initio thermochemistry (HEAT) theoretical model chemistry. It is found that the addition of these ostensible improvements does little to increase the overall accuracy of HEAT for the determination of molecular atomization energies. Fortuitous cancellation of high-level effects is shown to give the overall HEAT strategy an accuracy that is, in fact, higher than most of its individual components. In addition, the issue of core-valence electron correlation separation is explored; it is found that approximate additive treatments of the two effects have limitations that are significant in the realm of <1 kJ mol{sup -1} theoretical thermochemistry.

  18. High-Accuracy, Compact Scanning Method and Circuit for Resistive Sensor Arrays.

    PubMed

    Kim, Jong-Seok; Kwon, Dae-Yong; Choi, Byong-Deok

    2016-01-01

    The zero-potential scanning circuit is widely used as read-out circuit for resistive sensor arrays because it removes a well known problem: crosstalk current. The zero-potential scanning circuit can be divided into two groups based on type of row drivers. One type is a row driver using digital buffers. It can be easily implemented because of its simple structure, but we found that it can cause a large read-out error which originates from on-resistance of the digital buffers used in the row driver. The other type is a row driver composed of operational amplifiers. It, very accurately, reads the sensor resistance, but it uses a large number of operational amplifiers to drive rows of the sensor array; therefore, it severely increases the power consumption, cost, and system complexity. To resolve the inaccuracy or high complexity problems founded in those previous circuits, we propose a new row driver which uses only one operational amplifier to drive all rows of a sensor array with high accuracy. The measurement results with the proposed circuit to drive a 4 × 4 resistor array show that the maximum error is only 0.1% which is remarkably reduced from 30.7% of the previous counterpart. PMID:26821029

  19. Modern geodetic methods for high-accuracy survey coordination on the example of magnetic exploration

    NASA Astrophysics Data System (ADS)

    Krasnoperov, R. I.; Sidorov, R. V.; Soloviev, A. A.

    2015-07-01

    The purposes and problems of the international network of geomagnetic observatories INTERMAGNET are briefly described in the work. The importance of the development of the Russian segment of the network as a part of a system for monitoring and estimating geomagnetic conditions on the Russian territory is emphasized. An example of the use of modern high-precision geodetic equipment for coor-dinate referencing of field geophysical observation is described. Factors that distort the referencing of field observations in problems of survey, engineering, and technical geophysics are listed, as well as those related to detail and high-resolution geophysical surveying and those that require a corresponding accuracy of observation point coordination. The magnetic exploration at the site of the Yamal INTERMAGNET-standard observatory serves an example to describe a technique for geodetic provision of a detailed geophysical survey by means of joint use of differential GNSS measurements and electronic tacheometry. The main advantages and disadvantages of the technique suggested are listed.

  20. High-Accuracy, Compact Scanning Method and Circuit for Resistive Sensor Arrays

    PubMed Central

    Kim, Jong-Seok; Kwon, Dae-Yong; Choi, Byong-Deok

    2016-01-01

    The zero-potential scanning circuit is widely used as read-out circuit for resistive sensor arrays because it removes a well known problem: crosstalk current. The zero-potential scanning circuit can be divided into two groups based on type of row drivers. One type is a row driver using digital buffers. It can be easily implemented because of its simple structure, but we found that it can cause a large read-out error which originates from on-resistance of the digital buffers used in the row driver. The other type is a row driver composed of operational amplifiers. It, very accurately, reads the sensor resistance, but it uses a large number of operational amplifiers to drive rows of the sensor array; therefore, it severely increases the power consumption, cost, and system complexity. To resolve the inaccuracy or high complexity problems founded in those previous circuits, we propose a new row driver which uses only one operational amplifier to drive all rows of a sensor array with high accuracy. The measurement results with the proposed circuit to drive a 4 × 4 resistor array show that the maximum error is only 0.1% which is remarkably reduced from 30.7% of the previous counterpart. PMID:26821029