Science.gov

Sample records for accurate experimental measurements

  1. The accurate measurement of second virial coefficients using self-interaction chromatography: experimental considerations.

    PubMed

    Quigley, A; Heng, J Y Y; Liddell, J M; Williams, D R

    2013-11-01

    Measurement of B22, the second virial coefficient, is an important technique for describing the solution behaviour of proteins, especially as it relates to precipitation, aggregation and crystallisation phenomena. This paper describes the best practise for calculating B22 values from self-interaction chromatograms (SIC) for aqueous protein solutions. Detailed analysis of SIC peak shapes for lysozyme shows that non-Gaussian peaks are commonly encountered for SIC, with typical peak asymmetries of 10%. This asymmetry reflects a non-linear chromatographic retention process, in this case heterogeneity of the protein-protein interactions. Therefore, it is important to use the centre of mass calculations for determining accurate retention volumes and thus B22 values. Empirical peak maximum chromatogram analysis, often reported in the literature, can result in errors of up to 50% in B22 values. A methodology is reported here for determining both the mean and the variance in B22 from SIC experiments, includes a correction for normal longitudinal peak broadening. The variance in B22 due to chemical effects is quantified statistically and is a measure of the heterogeneity of protein-protein interactions in solution. In the case of lysozyme, a wide range of B22 values are measured which can vary significantly from the average B22 values.

  2. Accurate modeling of antennas for radiating short pulses, FDTD analysis and experimental measurements

    NASA Astrophysics Data System (ADS)

    Maloney, James G.; Smith, Glenn S.

    1993-01-01

    Antennas used to radiate short pulses often require different design rules that those that are used to radiate essentially time-harmonic signals. The finite-difference time-domain (FDTD) method is a very flexible numerical approach that can be used to treat a variety of electromagnetic problems in the time domain. It is well suited to the analysis and design of antennas for radiating short pulses; however, several advances had to be made before the method could be applied to this problem. In this paper, we will illustrate the use of the FDTD method with two antennas designed for the radiation of short pulses. The first is a simple, two-dimensional geometry, and open-ended parallel-plate waveguide, while the second is a three-dimensional, rotationally symmetric geometry, a conical monopole fed through an image by a coaxial transmission line. Both antennas are 'optimized' according to given criteria by adjusting geometrical parameters and including resistive loading that varies continuously with position along the antenna. The predicted performance for the conical monopole antenna is compared with experimental measurements; this verifies the optimization and demonstrates the practicality of the design.

  3. Accurate spectral color measurements

    NASA Astrophysics Data System (ADS)

    Hiltunen, Jouni; Jaeaeskelaeinen, Timo; Parkkinen, Jussi P. S.

    1999-08-01

    Surface color measurement is of importance in a very wide range of industrial applications including paint, paper, printing, photography, textiles, plastics and so on. For a demanding color measurements spectral approach is often needed. One can measure a color spectrum with a spectrophotometer using calibrated standard samples as a reference. Because it is impossible to define absolute color values of a sample, we always work with approximations. The human eye can perceive color difference as small as 0.5 CIELAB units and thus distinguish millions of colors. This 0.5 unit difference should be a goal for the precise color measurements. This limit is not a problem if we only want to measure the color difference of two samples, but if we want to know in a same time exact color coordinate values accuracy problems arise. The values of two instruments can be astonishingly different. The accuracy of the instrument used in color measurement may depend on various errors such as photometric non-linearity, wavelength error, integrating sphere dark level error, integrating sphere error in both specular included and specular excluded modes. Thus the correction formulas should be used to get more accurate results. Another question is how many channels i.e. wavelengths we are using to measure a spectrum. It is obvious that the sampling interval should be short to get more precise results. Furthermore, the result we get is always compromise of measuring time, conditions and cost. Sometimes we have to use portable syste or the shape and the size of samples makes it impossible to use sensitive equipment. In this study a small set of calibrated color tiles measured with the Perkin Elmer Lamda 18 and the Minolta CM-2002 spectrophotometers are compared. In the paper we explain the typical error sources of spectral color measurements, and show which are the accuracy demands a good colorimeter should have.

  4. An experimental device for accurate ultrasounds measurements in liquid foods at high pressure

    NASA Astrophysics Data System (ADS)

    Hidalgo-Baltasar, E.; Taravillo, M.; Baonza, V. G.; Sanz, P. D.; Guignon, B.

    2012-12-01

    The use of high hydrostatic pressure to ensure safe and high-quality product has markedly increased in the food industry during the last decade. Ultrasonic sensors can be employed to control such processes in an equivalent way as they are currently used in processes carried out at room pressure. However, their installation, calibration and use are particularly challenging in the context of a high pressure environment. Besides, data about acoustic properties of food under pressure and even for water are quite scarce in the pressure range of interest for food treatment (namely, above 200 MPa). The objective of this work was to establish a methodology to determine the speed of sound in foods under pressure. An ultrasonic sensor using the multiple reflections method was adapted to a lab-scale HHP equipment to determine the speed of sound in water between 253.15 and 348.15 K, and at pressures up to 700 MPa. The experimental speed-of-sound data were compared to the data calculated from the equation of state of water (IAPWS-95 formulation). From this analysis, the way to calibrate cell path was validated. After this calibration procedure, the speed of sound could be determined in liquid foods by using this sensor with a relative uncertainty between (0.22 and 0.32) % at a confidence level of 95 % over the whole pressure domain.

  5. A fast experimental beam hardening correction method for accurate bone mineral measurements in 3D μCT imaging system.

    PubMed

    Koubar, Khodor; Bekaert, Virgile; Brasse, David; Laquerriere, Patrice

    2015-06-01

    Bone mineral density plays an important role in the determination of bone strength and fracture risks. Consequently, it is very important to obtain accurate bone mineral density measurements. The microcomputerized tomography system provides 3D information about the architectural properties of bone. Quantitative analysis accuracy is decreased by the presence of artefacts in the reconstructed images, mainly due to beam hardening artefacts (such as cupping artefacts). In this paper, we introduced a new beam hardening correction method based on a postreconstruction technique performed with the use of off-line water and bone linearization curves experimentally calculated aiming to take into account the nonhomogeneity in the scanned animal. In order to evaluate the mass correction rate, calibration line has been carried out to convert the reconstructed linear attenuation coefficient into bone masses. The presented correction method was then applied on a multimaterial cylindrical phantom and on mouse skeleton images. Mass correction rate up to 18% between uncorrected and corrected images were obtained as well as a remarkable improvement of a calculated mouse femur mass has been noticed. Results were also compared to those obtained when using the simple water linearization technique which does not take into account the nonhomogeneity in the object.

  6. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  7. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  8. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  9. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  10. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  11. Accurate measurement of unsteady state fluid temperature

    NASA Astrophysics Data System (ADS)

    Jaremkiewicz, Magdalena

    2017-03-01

    In this paper, two accurate methods for determining the transient fluid temperature were presented. Measurements were conducted for boiling water since its temperature is known. At the beginning the thermometers are at the ambient temperature and next they are immediately immersed into saturated water. The measurements were carried out with two thermometers of different construction but with the same housing outer diameter equal to 15 mm. One of them is a K-type industrial thermometer widely available commercially. The temperature indicated by the thermometer was corrected considering the thermometers as the first or second order inertia devices. The new design of a thermometer was proposed and also used to measure the temperature of boiling water. Its characteristic feature is a cylinder-shaped housing with the sheath thermocouple located in its center. The temperature of the fluid was determined based on measurements taken in the axis of the solid cylindrical element (housing) using the inverse space marching method. Measurements of the transient temperature of the air flowing through the wind tunnel using the same thermometers were also carried out. The proposed measurement technique provides more accurate results compared with measurements using industrial thermometers in conjunction with simple temperature correction using the inertial thermometer model of the first or second order. By comparing the results, it was demonstrated that the new thermometer allows obtaining the fluid temperature much faster and with higher accuracy in comparison to the industrial thermometer. Accurate measurements of the fast changing fluid temperature are possible due to the low inertia thermometer and fast space marching method applied for solving the inverse heat conduction problem.

  12. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  13. Accurate, reproducible measurement of blood pressure.

    PubMed Central

    Campbell, N R; Chockalingam, A; Fodor, J G; McKay, D W

    1990-01-01

    The diagnosis of mild hypertension and the treatment of hypertension require accurate measurement of blood pressure. Blood pressure readings are altered by various factors that influence the patient, the techniques used and the accuracy of the sphygmomanometer. The variability of readings can be reduced if informed patients prepare in advance by emptying their bladder and bowel, by avoiding over-the-counter vasoactive drugs the day of measurement and by avoiding exposure to cold, caffeine consumption, smoking and physical exertion within half an hour before measurement. The use of standardized techniques to measure blood pressure will help to avoid large systematic errors. Poor technique can account for differences in readings of more than 15 mm Hg and ultimately misdiagnosis. Most of the recommended procedures are simple and, when routinely incorporated into clinical practice, require little additional time. The equipment must be appropriate and in good condition. Physicians should have a suitable selection of cuff sizes readily available; the use of the correct cuff size is essential to minimize systematic errors in blood pressure measurement. Semiannual calibration of aneroid sphygmomanometers and annual inspection of mercury sphygmomanometers and blood pressure cuffs are recommended. We review the methods recommended for measuring blood pressure and discuss the factors known to produce large differences in blood pressure readings. PMID:2192791

  14. Apparatus for accurately measuring high temperatures

    DOEpatents

    Smith, D.D.

    The present invention is a thermometer used for measuring furnace temperatures in the range of about 1800/sup 0/ to 2700/sup 0/C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

  15. Apparatus for accurately measuring high temperatures

    DOEpatents

    Smith, Douglas D.

    1985-01-01

    The present invention is a thermometer used for measuring furnace temperaes in the range of about 1800.degree. to 2700.degree. C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

  16. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: Application to pure copper, platinum, tungsten, and nickel at very high temperatures

    NASA Astrophysics Data System (ADS)

    Abadlia, L.; Gasser, F.; Khalouk, K.; Mayoufi, M.; Gasser, J. G.

    2014-09-01

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  17. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: application to pure copper, platinum, tungsten, and nickel at very high temperatures.

    PubMed

    Abadlia, L; Gasser, F; Khalouk, K; Mayoufi, M; Gasser, J G

    2014-09-01

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  18. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: Application to pure copper, platinum, tungsten, and nickel at very high temperatures

    SciTech Connect

    Abadlia, L.; Mayoufi, M.; Gasser, F.; Khalouk, K.; Gasser, J. G.

    2014-09-15

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  19. Fast and accurate exhaled breath ammonia measurement.

    PubMed

    Solga, Steven F; Mudalel, Matthew L; Spacek, Lisa A; Risby, Terence H

    2014-06-11

    This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Together with the quick response time of the monitor, this system is capable of accurately measuring exhaled breath ammonia representative of deep lung systemic levels. Because the system is easy to use and produces real time results, it has enabled experiments to identify factors that influence measurements. For example, mouth rinse and oral pH reproducibly and significantly affect results and therefore must be controlled. Temperature and mode of breathing are other examples. As our understanding of these factors evolves, error is reduced, and clinical studies become more meaningful. This system is very reliable and individual measurements are inexpensive. The sampler is relatively inexpensive and quite portable, but the monitor is neither. This limits options for some clinical studies and provides rational for future innovations.

  20. Highly accurate articulated coordinate measuring machine

    DOEpatents

    Bieg, Lothar F.; Jokiel, Jr., Bernhard; Ensz, Mark T.; Watson, Robert D.

    2003-12-30

    Disclosed is a highly accurate articulated coordinate measuring machine, comprising a revolute joint, comprising a circular encoder wheel, having an axis of rotation; a plurality of marks disposed around at least a portion of the circumference of the encoder wheel; bearing means for supporting the encoder wheel, while permitting free rotation of the encoder wheel about the wheel's axis of rotation; and a sensor, rigidly attached to the bearing means, for detecting the motion of at least some of the marks as the encoder wheel rotates; a probe arm, having a proximal end rigidly attached to the encoder wheel, and having a distal end with a probe tip attached thereto; and coordinate processing means, operatively connected to the sensor, for converting the output of the sensor into a set of cylindrical coordinates representing the position of the probe tip relative to a reference cylindrical coordinate system.

  1. Accurately measuring dynamic coefficient of friction in ultraform finishing

    NASA Astrophysics Data System (ADS)

    Briggs, Dennis; Echaves, Samantha; Pidgeon, Brendan; Travis, Nathan; Ellis, Jonathan D.

    2013-09-01

    UltraForm Finishing (UFF) is a deterministic sub-aperture computer numerically controlled grinding and polishing platform designed by OptiPro Systems. UFF is used to grind and polish a variety of optics from simple spherical to fully freeform, and numerous materials from glasses to optical ceramics. The UFF system consists of an abrasive belt around a compliant wheel that rotates and contacts the part to remove material. This work aims to accurately measure the dynamic coefficient of friction (μ), how it changes as a function of belt wear, and how this ultimately affects material removal rates. The coefficient of friction has been examined in terms of contact mechanics and Preston's equation to determine accurate material removal rates. By accurately predicting changes in μ, polishing iterations can be more accurately predicted, reducing the total number of iterations required to meet specifications. We have established an experimental apparatus that can accurately measure μ by measuring triaxial forces during translating loading conditions or while manufacturing the removal spots used to calculate material removal rates. Using this system, we will demonstrate μ measurements for UFF belts during different states of their lifecycle and assess the material removal function from spot diagrams as a function of wear. Ultimately, we will use this system for qualifying belt-wheel-material combinations to develop a spot-morphing model to better predict instantaneous material removal functions.

  2. Accurate measurement of streamwise vortices using dual-plane PIV

    NASA Astrophysics Data System (ADS)

    Waldman, Rye M.; Breuer, Kenneth S.

    2012-11-01

    Low Reynolds number aerodynamic experiments with flapping animals (such as bats and small birds) are of particular interest due to their application to micro air vehicles which operate in a similar parameter space. Previous PIV wake measurements described the structures left by bats and birds and provided insight into the time history of their aerodynamic force generation; however, these studies have faced difficulty drawing quantitative conclusions based on said measurements. The highly three-dimensional and unsteady nature of the flows associated with flapping flight are major challenges for accurate measurements. The challenge of animal flight measurements is finding small flow features in a large field of view at high speed with limited laser energy and camera resolution. Cross-stream measurement is further complicated by the predominately out-of-plane flow that requires thick laser sheets and short inter-frame times, which increase noise and measurement uncertainty. Choosing appropriate experimental parameters requires compromise between the spatial and temporal resolution and the dynamic range of the measurement. To explore these challenges, we do a case study on the wake of a fixed wing. The fixed model simplifies the experiment and allows direct measurements of the aerodynamic forces via load cell. We present a detailed analysis of the wake measurements, discuss the criteria for making accurate measurements, and present a solution for making quantitative aerodynamic load measurements behind free-flyers.

  3. Considerations for Accurate Whole Plant Photosynthesis Measurement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole plant photosynthetic rate (Pn) measurements provide an integral assessment of how an entire plant responds to biotic and abitics factors. Pn determination is based on measurements of CO2 exchange rates (CER) using various types of system including Closed, Semi-closed, and Open systems. This ...

  4. A unique, accurate LWIR optics measurement system

    NASA Astrophysics Data System (ADS)

    Fantone, Stephen D.; Orband, Daniel G.

    2011-05-01

    A compact low-cost LWIR test station has been developed that provides real time MTF testing of IR optical systems and EO imaging systems. The test station is intended to be operated by a technician and can be used to measure the focal length, blur spot size, distortion, and other metrics of system performance. The challenges and tradeoffs incorporated into this instrumentation will be presented. The test station performs the measurement of an IR lens or optical system's first order quantities (focal length, back focal length) including on and off-axis imaging performance (e.g., MTF, resolution, spot size) under actual test conditions to enable the simulation of their actual use. Also described is the method of attaining the needed accuracies so that derived calculations like focal length (EFL = image shift/tan(theta)) can be performed to the requisite accuracy. The station incorporates a patented video capture technology and measures MTF and blur characteristics using newly available lowcost LWIR cameras. This allows real time determination of the optical system performance enabling faster measurements, higher throughput and lower cost results than scanning systems. Multiple spectral filters are also accommodated within the test stations which facilitate performance evaluation under various spectral conditions.

  5. Instrument accurately measures weld angle and offset

    NASA Technical Reports Server (NTRS)

    Boyd, W. G.

    1967-01-01

    Weld angle is measured to the nearest arc minute and offset to one thousandth of an inch by an instrument designed to use a reference plane at two locations on a test coupon. A special table for computation has been prepared for use with the instrument.

  6. Air brake-dynamometer accurately measures torque

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Air brake-dynamometer assembly combines the principles of the air turbine and the air pump to apply braking torque. The assembly absorbs and measures power outputs of rotating machinery over a wide range of shaft speeds. It can also be used as an air turbine.

  7. Modified algesimeter provides accurate depth measurements

    NASA Technical Reports Server (NTRS)

    Turner, D. P.

    1966-01-01

    Algesimeter which incorporates a standard sensory needle with a sensitive micrometer, measures needle point depth penetration in pain tolerance research. This algesimeter provides an inexpensive, precise instrument with assured validity of recordings in those biomedical areas with a requirement for repeated pain detection or ascertaining pain sensitivity.

  8. EMR Gage Would Measure Coal Thickness Accurately

    NASA Technical Reports Server (NTRS)

    King, J. D.; Rollwitz, W. L.

    1982-01-01

    Laboratory tests indicate electron magnetic resonance (EMR) would be effective in measuring thickness of coal overlying rock substrate. In prototype dual-frequency EMR system, Sample is irradiated by two radio frequencies. Signals are mixed, producing sum and difference output frequencies that are detected by receiver. Magnetic field is varied to scan resonant spot through sample. In system designed for field use, electromagnet is U-shaped, so that sample can be adjacent to, rather than inside the probe. Same coil is used for transmitting and receiving.

  9. Accurate Measurement of Bone Density with QCT

    NASA Technical Reports Server (NTRS)

    Cleek, Tammy M.; Beaupre, Gary S.; Matsubara, Miki; Whalen, Robert T.; Dalton, Bonnie P. (Technical Monitor)

    2002-01-01

    The objective of this study was to determine the accuracy of bone density measurement with a new OCT technology. A phantom was fabricated using two materials, a water-equivalent compound and hydroxyapatite (HA), combined in precise proportions (QRM GrnbH, Germany). The phantom was designed to have the approximate physical size and range in bone density as a human calcaneus, with regions of 0, 50, 100, 200, 400, and 800 mg/cc HA. The phantom was scanned at 80, 120 and 140 KVp with a GE CT/i HiSpeed Advantage scanner. A ring of highly attenuating material (polyvinyl chloride or teflon) was slipped over the phantom to alter the image by introducing non-axi-symmetric beam hardening. Images were corrected with a new OCT technology using an estimate of the effective X-ray beam spectrum to eliminate beam hardening artifacts. The algorithm computes the volume fraction of HA and water-equivalent matrix in each voxel. We found excellent agreement between expected and computed HA volume fractions. Results were insensitive to beam hardening ring material, HA concentration, and scan voltage settings. Data from all 3 voltages with a best fit linear regression are displays.

  10. Accurate measurement of streamwise vortices in low speed aerodynamic flows

    NASA Astrophysics Data System (ADS)

    Waldman, Rye M.; Kudo, Jun; Breuer, Kenneth S.

    2010-11-01

    Low Reynolds number experiments with flapping animals (such as bats and small birds) are of current interest in understanding biological flight mechanics, and due to their application to Micro Air Vehicles (MAVs) which operate in a similar parameter space. Previous PIV wake measurements have described the structures left by bats and birds, and provided insight to the time history of their aerodynamic force generation; however, these studies have faced difficulty drawing quantitative conclusions due to significant experimental challenges associated with the highly three-dimensional and unsteady nature of the flows, and the low wake velocities associated with lifting bodies that only weigh a few grams. This requires the high-speed resolution of small flow features in a large field of view using limited laser energy and finite camera resolution. Cross-stream measurements are further complicated by the high out-of-plane flow which requires thick laser sheets and short interframe times. To quantify and address these challenges we present data from a model study on the wake behind a fixed wing at conditions comparable to those found in biological flight. We present a detailed analysis of the PIV wake measurements, discuss the criteria necessary for accurate measurements, and present a new dual-plane PIV configuration to resolve these issues.

  11. Accurate Fiber Length Measurement Using Time-of-Flight Technique

    NASA Astrophysics Data System (ADS)

    Terra, Osama; Hussein, Hatem

    2016-06-01

    Fiber artifacts of very well-measured length are required for the calibration of optical time domain reflectometers (OTDR). In this paper accurate length measurement of different fiber lengths using the time-of-flight technique is performed. A setup is proposed to measure accurately lengths from 1 to 40 km at 1,550 and 1,310 nm using high-speed electro-optic modulator and photodetector. This setup offers traceability to the SI unit of time, the second (and hence to meter by definition), by locking the time interval counter to the Global Positioning System (GPS)-disciplined quartz oscillator. Additionally, the length of a recirculating loop artifact is measured and compared with the measurement made for the same fiber by the National Physical Laboratory of United Kingdom (NPL). Finally, a method is proposed to relatively correct the fiber refractive index to allow accurate fiber length measurement.

  12. Accurate multipixel phase measurement with classical-light interferometry

    NASA Astrophysics Data System (ADS)

    Singh, Mandeep; Khare, Kedar; Jha, Anand Kumar; Prabhakar, Shashi; Singh, R. P.

    2015-02-01

    We demonstrate accurate phase measurement from experimental low photon level interferograms using a constrained optimization method that takes into account the expected redundancy in the unknown phase function. This approach is shown to have significant noise advantage over traditional methods, such as balanced homodyning or phase shifting, that treat individual pixels in the interference data as independent of each other. Our interference experiments comparing the optimization method with the traditional phase-shifting method show that when the same photon resources are used, the optimization method provides phase recoveries with tighter error bars. In particular, rms phase error performance of the optimization method for low photon number data (10 photons per pixel) shows a >5 × noise gain over the phase-shifting method. In our experiments where a laser light source is used for illumination, the results imply phase measurement with an accuracy better than the conventional single-pixel-based shot-noise limit that assumes independent phases at individual pixels. The constrained optimization approach presented here is independent of the nature of the light source and may further enhance the accuracy of phase detection when a nonclassical-light source is used.

  13. Accurate Insertion Loss Measurements of the Juno Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Chen, Jacqueline; Hodges, Richard; Demas, John

    2010-01-01

    This paper describes two independent methods for estimating the insertion loss of patch array antennas that were developed for the Juno Microwave Radiometer instrument. One method is based principally on pattern measurements while the other method is based solely on network analyzer measurements. The methods are accurate to within 0.1 dB for the measured antennas and show good agreement (to within 0.1dB) of separate radiometric measurements.

  14. Ultrasonic system for accurate distance measurement in the air.

    PubMed

    Licznerski, Tomasz J; Jaroński, Jarosław; Kosz, Dariusz

    2011-12-01

    This paper presents a system that accurately measures the distance travelled by ultrasound waves through the air. The simple design of the system and its obtained accuracy provide a tool for non-contact distance measurements required in the laser's optical system that investigates the surface of the eyeball.

  15. History and progress on accurate measurements of the Planck constant

    NASA Astrophysics Data System (ADS)

    Steiner, Richard

    2013-01-01

    The measurement of the Planck constant, h, is entering a new phase. The CODATA 2010 recommended value is 6.626 069 57 × 10-34 J s, but it has been a long road, and the trip is not over yet. Since its discovery as a fundamental physical constant to explain various effects in quantum theory, h has become especially important in defining standards for electrical measurements and soon, for mass determination. Measuring h in the International System of Units (SI) started as experimental attempts merely to prove its existence. Many decades passed while newer experiments measured physical effects that were the influence of h combined with other physical constants: elementary charge, e, and the Avogadro constant, NA. As experimental techniques improved, the precision of the value of h expanded. When the Josephson and quantum Hall theories led to new electronic devices, and a hundred year old experiment, the absolute ampere, was altered into a watt balance, h not only became vital in definitions for the volt and ohm units, but suddenly it could be measured directly and even more accurately. Finally, as measurement uncertainties now approach a few parts in 108 from the watt balance experiments and Avogadro determinations, its importance has been linked to a proposed redefinition of a kilogram unit of mass. The path to higher accuracy in measuring the value of h was not always an example of continuous progress. Since new measurements periodically led to changes in its accepted value and the corresponding SI units, it is helpful to see why there were bumps in the road and where the different branch lines of research joined in the effort. Recalling the bumps along this road will hopefully avoid their repetition in the upcoming SI redefinition debates. This paper begins with a brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant. The historical path is followed in the section describing how the improved

  16. History and progress on accurate measurements of the Planck constant.

    PubMed

    Steiner, Richard

    2013-01-01

    The measurement of the Planck constant, h, is entering a new phase. The CODATA 2010 recommended value is 6.626 069 57 × 10(-34) J s, but it has been a long road, and the trip is not over yet. Since its discovery as a fundamental physical constant to explain various effects in quantum theory, h has become especially important in defining standards for electrical measurements and soon, for mass determination. Measuring h in the International System of Units (SI) started as experimental attempts merely to prove its existence. Many decades passed while newer experiments measured physical effects that were the influence of h combined with other physical constants: elementary charge, e, and the Avogadro constant, N(A). As experimental techniques improved, the precision of the value of h expanded. When the Josephson and quantum Hall theories led to new electronic devices, and a hundred year old experiment, the absolute ampere, was altered into a watt balance, h not only became vital in definitions for the volt and ohm units, but suddenly it could be measured directly and even more accurately. Finally, as measurement uncertainties now approach a few parts in 10(8) from the watt balance experiments and Avogadro determinations, its importance has been linked to a proposed redefinition of a kilogram unit of mass. The path to higher accuracy in measuring the value of h was not always an example of continuous progress. Since new measurements periodically led to changes in its accepted value and the corresponding SI units, it is helpful to see why there were bumps in the road and where the different branch lines of research joined in the effort. Recalling the bumps along this road will hopefully avoid their repetition in the upcoming SI redefinition debates. This paper begins with a brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant. The historical path is followed in the section describing how the

  17. In-line sensor for accurate rf power measurements

    NASA Astrophysics Data System (ADS)

    Gahan, D.; Hopkins, M. B.

    2005-10-01

    An in-line sensor has been constructed with 50Ω characteristic impedance to accurately measure rf power dissipated in a matched or unmatched load with a view to being implemented as a rf discharge diagnostic. The physical construction and calibration technique are presented. The design is a wide band, hybrid directional coupler/current-voltage sensor suitable for fundamental and harmonic power measurements. A comparison with a standard wattmeter using dummy load impedances shows that this in-line sensor is significantly more accurate in mismatched conditions.

  18. In-line sensor for accurate rf power measurements

    SciTech Connect

    Gahan, D.; Hopkins, M.B.

    2005-10-15

    An in-line sensor has been constructed with 50 {omega} characteristic impedance to accurately measure rf power dissipated in a matched or unmatched load with a view to being implemented as a rf discharge diagnostic. The physical construction and calibration technique are presented. The design is a wide band, hybrid directional coupler/current-voltage sensor suitable for fundamental and harmonic power measurements. A comparison with a standard wattmeter using dummy load impedances shows that this in-line sensor is significantly more accurate in mismatched conditions.

  19. Device accurately measures and records low gas-flow rates

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

    Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

  20. Monitoring circuit accurately measures movement of solenoid valve

    NASA Technical Reports Server (NTRS)

    Gillett, J. D.

    1966-01-01

    Solenoid operated valve in a control system powered by direct current issued to accurately measure the valve travel. This system is currently in operation with a 28-vdc power system used for control of fluids in liquid rocket motor test facilities.

  1. Instrument accurately measures small temperature changes on test surface

    NASA Technical Reports Server (NTRS)

    Harvey, W. D.; Miller, H. B.

    1966-01-01

    Calorimeter apparatus accurately measures very small temperature rises on a test surface subjected to aerodynamic heating. A continuous thin sheet of a sensing material is attached to a base support plate through which a series of holes of known diameter have been drilled for attaching thermocouples to the material.

  2. A Simple and Accurate Method for Measuring Enzyme Activity.

    ERIC Educational Resources Information Center

    Yip, Din-Yan

    1997-01-01

    Presents methods commonly used for investigating enzyme activity using catalase and presents a new method for measuring catalase activity that is more reliable and accurate. Provides results that are readily reproduced and quantified. Can also be used for investigations of enzyme properties such as the effects of temperature, pH, inhibitors,…

  3. Ellipsoidal-mirror reflectometer accurately measures infrared reflectance of materials

    NASA Technical Reports Server (NTRS)

    Dunn, S. T.; Richmond, J. C.

    1967-01-01

    Reflectometer accurately measures the reflectance of specimens in the infrared beyond 2.5 microns and under geometric conditions approximating normal irradiation and hemispherical viewing. It includes an ellipsoidal mirror, a specially coated averaging sphere associated with a detector for minimizing spatial and angular sensitivity, and an incident flux chopper.

  4. Accurately measuring volcanic plume velocity with multiple UV spectrometers

    USGS Publications Warehouse

    Williams-Jones, Glyn; Horton, Keith A.; Elias, Tamar; Garbeil, Harold; Mouginis-Mark, Peter J; Sutton, A. Jeff; Harris, Andrew J. L.

    2006-01-01

    A fundamental problem with all ground-based remotely sensed measurements of volcanic gas flux is the difficulty in accurately measuring the velocity of the gas plume. Since a representative wind speed and direction are used as proxies for the actual plume velocity, there can be considerable uncertainty in reported gas flux values. Here we present a method that uses at least two time-synchronized simultaneously recording UV spectrometers (FLYSPECs) placed a known distance apart. By analyzing the time varying structure of SO2 concentration signals at each instrument, the plume velocity can accurately be determined. Experiments were conducted on Kīlauea (USA) and Masaya (Nicaragua) volcanoes in March and August 2003 at plume velocities between 1 and 10 m s−1. Concurrent ground-based anemometer measurements differed from FLYSPEC-measured plume speeds by up to 320%. This multi-spectrometer method allows for the accurate remote measurement of plume velocity and can therefore greatly improve the precision of volcanic or industrial gas flux measurements.

  5. Problems with Accurate Atomic Lfetime Measurements of Multiply Charged Ions

    SciTech Connect

    Trabert, E

    2009-02-19

    A number of recent atomic lifetime measurements on multiply charged ions have reported uncertainties lower than 1%. Such a level of accuracy challenges theory, which is a good thing. However, a few lessons learned from earlier precision lifetime measurements on atoms and singly charged ions suggest to remain cautious about the systematic errors of experimental techniques.

  6. Optical Fiber Geometry: Accurate Measurement of Cladding Diameter

    PubMed Central

    Young, Matt; Hale, Paul D.; Mechels, Steven E.

    1993-01-01

    We have developed three instruments for accurate measurement of optieal fiber cladding diameter: a contact micrometer, a scanning confocal microscope, and a white-light interference microscope. Each instrument has an estimated uncertainty (3 standard deviations) of 50 nm or less, but the confocal microscope may display a 20 nm systematic error as well. The micrometer is used to generate Standard Reference Materials that are commercially available. PMID:28053467

  7. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    PubMed Central

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  8. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    PubMed

    Shortis, Mark

    2015-12-07

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems.

  9. RTbox: a device for highly accurate response time measurements.

    PubMed

    Li, Xiangrui; Liang, Zhen; Kleiner, Mario; Lu, Zhong-Lin

    2010-02-01

    Although computer keyboards and mice are frequently used in measuring response times (RTs), the accuracy of these measurements is quite low. Specialized RT collection devices must be used to obtain more accurate measurements. However, all the existing devices have some shortcomings. We have developed and implemented a new, commercially available device, the RTbox, for highly accurate RT measurements. The RTbox has its own microprocessor and high-resolution clock. It can record the identities and timing of button events with high accuracy, unaffected by potential timing uncertainty or biases during data transmission and processing in the host computer. It stores button events until the host computer chooses to retrieve them. The asynchronous storage greatly simplifies the design of user programs. The RTbox can also receive and record external signals as triggers and can measure RTs with respect to external events. The internal clock of the RTbox can be synchronized with the computer clock, so the device can be used without external triggers. A simple USB connection is sufficient to integrate the RTbox with any standard computer and operating system.

  10. Accurate measurement of the helical twisting power of chiral dopants

    NASA Astrophysics Data System (ADS)

    Kosa, Tamas; Bodnar, Volodymyr; Taheri, Bahman; Palffy-Muhoray, Peter

    2002-03-01

    We propose a method for the accurate determination of the helical twisting power (HTP) of chiral dopants. In the usual Cano-wedge method, the wedge angle is determined from the far-field separation of laser beams reflected from the windows of the test cell. Here we propose to use an optical fiber based spectrometer to accurately measure the cell thickness. Knowing the cell thickness at the positions of the disclination lines allows determination of the HTP. We show that this extension of the Cano-wedge method greatly increases the accuracy with which the HTP is determined. We show the usefulness of this method by determining the HTP of ZLI811 in a variety of hosts with negative dielectric anisotropy.

  11. Experimental and theoretical oscillator strengths of Mg i for accurate abundance analysis

    NASA Astrophysics Data System (ADS)

    Pehlivan Rhodin, A.; Hartman, H.; Nilsson, H.; Jönsson, P.

    2017-02-01

    Context. With the aid of stellar abundance analysis, it is possible to study the galactic formation and evolution. Magnesium is an important element to trace the α-element evolution in our Galaxy. For chemical abundance analysis, such as magnesium abundance, accurate and complete atomic data are essential. Inaccurate atomic data lead to uncertain abundances and prevent discrimination between different evolution models. Aims: We study the spectrum of neutral magnesium from laboratory measurements and theoretical calculations. Our aim is to improve the oscillator strengths (f-values) of Mg i lines and to create a complete set of accurate atomic data, particularly for the near-IR region. Methods: We derived oscillator strengths by combining the experimental branching fractions with radiative lifetimes reported in the literature and computed in this work. A hollow cathode discharge lamp was used to produce free atoms in the plasma and a Fourier transform spectrometer recorded the intensity-calibrated high-resolution spectra. In addition, we performed theoretical calculations using the multiconfiguration Hartree-Fock program ATSP2K. Results: This project provides a set of experimental and theoretical oscillator strengths. We derived 34 experimental oscillator strengths. Except from the Mg i optical triplet lines (3p 3P°0,1,2-4s 3S1), these oscillator strengths are measured for the first time. The theoretical oscillator strengths are in very good agreement with the experimental data and complement the missing transitions of the experimental data up to n = 7 from even and odd parity terms. We present an evaluated set of oscillator strengths, gf, with uncertainties as small as 5%. The new values of the Mg i optical triplet line (3p 3P°0,1,2-4s 3S1) oscillator strength values are 0.08 dex larger than the previous measurements.

  12. Accurate Runout Measurement for HDD Spinning Motors and Disks

    NASA Astrophysics Data System (ADS)

    Jiang, Quan; Bi, Chao; Lin, Song

    As hard disk drive (HDD) areal density increases, its track width becomes smaller and smaller and so is non-repeatable runout. HDD industry needs more accurate and better resolution runout measurements of spinning spindle motors and media platters in both axial and radial directions. This paper introduces a new system how to precisely measure the runout of HDD spinning disks and motors through synchronously acquiring the rotor position signal and the displacements in axial or radial directions. In order to minimize the synchronizing error between the rotor position and the displacement signal, a high resolution counter is adopted instead of the conventional phase-lock loop method. With Laser Doppler Vibrometer and proper signal processing, the proposed runout system can precisely measure the runout of the HDD spinning disks and motors with 1 nm resolution and 0.2% accuracy with a proper sampling rate. It can provide an effective and accurate means to measure the runout of high areal density HDDs, in particular the next generation HDDs, such as, pattern media HDDs and HAMR HDDs.

  13. Accurate measurement method for tube's endpoints based on machine vision

    NASA Astrophysics Data System (ADS)

    Liu, Shaoli; Jin, Peng; Liu, Jianhua; Wang, Xiao; Sun, Peng

    2017-01-01

    Tubes are used widely in aerospace vehicles, and their accurate assembly can directly affect the assembling reliability and the quality of products. It is important to measure the processed tube's endpoints and then fix any geometric errors correspondingly. However, the traditional tube inspection method is time-consuming and complex operations. Therefore, a new measurement method for a tube's endpoints based on machine vision is proposed. First, reflected light on tube's surface can be removed by using photometric linearization. Then, based on the optimization model for the tube's endpoint measurements and the principle of stereo matching, the global coordinates and the relative distance of the tube's endpoint are obtained. To confirm the feasibility, 11 tubes are processed to remove the reflected light and then the endpoint's positions of tubes are measured. The experiment results show that the measurement repeatability accuracy is 0.167 mm, and the absolute accuracy is 0.328 mm. The measurement takes less than 1 min. The proposed method based on machine vision can measure the tube's endpoints without any surface treatment or any tools and can realize on line measurement.

  14. Accurate vessel width measurement from fundus photographs: a new concept.

    PubMed Central

    Rassam, S M; Patel, V; Brinchmann-Hansen, O; Engvold, O; Kohner, E M

    1994-01-01

    Accurate determination of retinal vessel width measurement is important in the study of the haemodynamic changes that accompany various physiological and pathological states. Currently the width at the half height of the transmittance and densitometry profiles are used as a measure of retinal vessel width. A consistent phenomenon of two 'kick points' on the slopes of the transmittance and densitometry profiles near the base, has been observed. In this study, mathematical models have been formulated to describe the characteristic curves of the transmittance and the densitometry profiles. They demonstrate the kick points being coincident with the edges of the blood column. The horizontal distance across the kick points would therefore indicate the actual blood column width. To evaluate this hypothesis, blood was infused through two lengths of plastic tubing of known diameters, and photographed. In comparison with the known diameters, the half height underestimated the blood column width by 7.33% and 6.46%, while the kick point method slightly overestimated it by 1.40% and 0.34%. These techniques were applied to monochromatic fundus photographs. In comparison with the kick point method, the half height underestimated the blood column width in veins by 16.67% and in arteries by 15.86%. The characteristics of the kick points and their practicality have been discussed. The kick point method may provide the most accurate measurement of vessel width possible from these profiles. Images PMID:8110693

  15. Accurate Sound Velocity Measurement in Ocean Near-Surface Layer

    NASA Astrophysics Data System (ADS)

    Lizarralde, D.; Xu, B. L.

    2015-12-01

    Accurate sound velocity measurement is essential in oceanography because sound is the only wave that can propagate in sea water. Due to its measuring difficulties, sound velocity is often not measured directly but instead calculated from water temperature, salinity, and depth, which are much easier to obtain. This research develops a new method to directly measure the sound velocity in the ocean's near-surface layer using multi-channel seismic (MCS) hydrophones. This system consists of a device to make a sound pulse and a long cable with hundreds of hydrophones to record the sound. The distance between the source and each receiver is the offset. The time it takes the pulse to arrive to each receiver is the travel time.The errors of measuring offset and travel time will affect the accuracy of sound velocity if we calculated with just one offset and one travel time. However, by analyzing the direct arrival signal from hundreds of receivers, the velocity can be determined as the slope of a straight line in the travel time-offset graph. The errors in distance and time measurement result in only an up or down shift of the line and do not affect the slope. This research uses MCS data of survey MGL1408 obtained from the Marine Geoscience Data System and processed with Seismic Unix. The sound velocity can be directly measured to an accuracy of less than 1m/s. The included graph shows the directly measured velocity verses the calculated velocity along 100km across the Mid-Atlantic continental margin. The directly measured velocity shows a good coherence to the velocity computed from temperature and salinity. In addition, the fine variations in the sound velocity can be observed, which is hardly seen from the calculated velocity. Using this methodology, both large area acquisition and fine resolution can be achieved. This directly measured sound velocity will be a new and powerful tool in oceanography.

  16. Novel dispersion tolerant interferometry method for accurate measurements of displacement

    NASA Astrophysics Data System (ADS)

    Bradu, Adrian; Maria, Michael; Leick, Lasse; Podoleanu, Adrian G.

    2015-05-01

    We demonstrate that the recently proposed master-slave interferometry method is able to provide true dispersion free depth profiles in a spectrometer-based set-up that can be used for accurate displacement measurements in sensing and optical coherence tomography. The proposed technique is based on correlating the channelled spectra produced by the linear camera in the spectrometer with previously recorded masks. As such technique is not based on Fourier transformations (FT), it does not require any resampling of data and is immune to any amounts of dispersion left unbalanced in the system. In order to prove the tolerance of technique to dispersion, different lengths of optical fiber are used in the interferometer to introduce dispersion and it is demonstrated that neither the sensitivity profile versus optical path difference (OPD) nor the depth resolution are affected. In opposition, it is shown that the classical FT based methods using calibrated data provide less accurate optical path length measurements and exhibit a quicker decays of sensitivity with OPD.

  17. Accurate and precise zinc isotope ratio measurements in urban aerosols.

    PubMed

    Gioia, Simone; Weiss, Dominik; Coles, Barry; Arnold, Tim; Babinski, Marly

    2008-12-15

    We developed an analytical method and constrained procedural boundary conditions that enable accurate and precise Zn isotope ratio measurements in urban aerosols. We also demonstrate the potential of this new isotope system for air pollutant source tracing. The procedural blank is around 5 ng and significantly lower than published methods due to a tailored ion chromatographic separation. Accurate mass bias correction using external correction with Cu is limited to Zn sample content of approximately 50 ng due to the combined effect of blank contribution of Cu and Zn from the ion exchange procedure and the need to maintain a Cu/Zn ratio of approximately 1. Mass bias is corrected for by applying the common analyte internal standardization method approach. Comparison with other mass bias correction methods demonstrates the accuracy of the method. The average precision of delta(66)Zn determinations in aerosols is around 0.05 per thousand per atomic mass unit. The method was tested on aerosols collected in Sao Paulo City, Brazil. The measurements reveal significant variations in delta(66)Zn(Imperial) ranging between -0.96 and -0.37 per thousand in coarse and between -1.04 and 0.02 per thousand in fine particular matter. This variability suggests that Zn isotopic compositions distinguish atmospheric sources. The isotopic light signature suggests traffic as the main source. We present further delta(66)Zn(Imperial) data for the standard reference material NIST SRM 2783 (delta(66)Zn(Imperial) = 0.26 +/- 0.10 per thousand).

  18. Accurate measurement of the pulse wave delay with imaging photoplethysmography

    PubMed Central

    Kamshilin, Alexei A.; Sidorov, Igor S.; Babayan, Laura; Volynsky, Maxim A.; Giniatullin, Rashid; Mamontov, Oleg V.

    2016-01-01

    Assessment of the cardiovascular parameters using noncontact video-based or imaging photoplethysmography (IPPG) is usually considered as inaccurate because of strong influence of motion artefacts. To optimize this technique we performed a simultaneous recording of electrocardiogram and video frames of the face for 36 healthy volunteers. We found that signal disturbances originate mainly from the stochastically enhanced dichroic notch caused by endogenous cardiovascular mechanisms, with smaller contribution of the motion artefacts. Our properly designed algorithm allowed us to increase accuracy of the pulse-transit-time measurement and visualize propagation of the pulse wave in the facial region. Thus, the accurate measurement of the pulse wave parameters with this technique suggests a sensitive approach to assess local regulation of microcirculation in various physiological and pathological states. PMID:28018731

  19. A spectroscopic transfer standard for accurate atmospheric CO measurements

    NASA Astrophysics Data System (ADS)

    Nwaboh, Javis A.; Li, Gang; Serdyukov, Anton; Werhahn, Olav; Ebert, Volker

    2016-04-01

    Atmospheric carbon monoxide (CO) is a precursor of essential climate variables and has an indirect effect for enhancing global warming. Accurate and reliable measurements of atmospheric CO concentration are becoming indispensable. WMO-GAW reports states a compatibility goal of ±2 ppb for atmospheric CO concentration measurements. Therefore, the EMRP-HIGHGAS (European metrology research program - high-impact greenhouse gases) project aims at developing spectroscopic transfer standards for CO concentration measurements to meet this goal. A spectroscopic transfer standard would provide results that are directly traceable to the SI, can be very useful for calibration of devices operating in the field, and could complement classical gas standards in the field where calibration gas mixtures in bottles often are not accurate, available or stable enough [1][2]. Here, we present our new direct tunable diode laser absorption spectroscopy (dTDLAS) sensor capable of performing absolute ("calibration free") CO concentration measurements, and being operated as a spectroscopic transfer standard. To achieve the compatibility goal stated by WMO for CO concentration measurements and ensure the traceability of the final concentration results, traceable spectral line data especially line intensities with appropriate uncertainties are needed. Therefore, we utilize our new high-resolution Fourier-transform infrared (FTIR) spectroscopy CO line data for the 2-0 band, with significantly reduced uncertainties, for the dTDLAS data evaluation. Further, we demonstrate the capability of our sensor for atmospheric CO measurements, discuss uncertainty calculation following the guide to the expression of uncertainty in measurement (GUM) principles and show that CO concentrations derived using the sensor, based on the TILSAM (traceable infrared laser spectroscopic amount fraction measurement) method, are in excellent agreement with gravimetric values. Acknowledgement Parts of this work have been

  20. Measurement and Accurate Interpretation of the Solubility of Pharmaceutical Salts.

    PubMed

    He, Yan; Ho, Chris; Yang, Donglai; Chen, Jeane; Orton, Edward

    2017-01-30

    Salt formation is one of the primary approaches to improve the developability of ionizable poorly water-soluble compounds. Solubility determination of the salt candidates in aqueous media or biorelevant fluids is a critical step in salt screening. Salt solubility measurements can be complicated due to dynamic changes in both solution and solid phases. Because of the early implementation of salt screening in research, solubility measurements often are performed using minimal amount of material. Some salts have transient high solubility on dissolution. Recognition of these transients can be critical in developing these salts into drug products. This minireview focuses on challenges in salt solubility measurements due to the changes in solution caused by self-buffering effects of dissolved species and the changes in solid phase due to solid-state phase transformations. Solubility measurements and their accurate interpretation are assessed in the context of dissolution monitoring and solid-phase analysis technologies. A harmonized method for reporting salt solubility measurements is recommended to reduce errors and to align with the U.S. Pharmacopeial policy and Food and Drug Administration recommendations for drug products containing pharmaceutical salts.

  1. Accurate measurement of RF exposure from emerging wireless communication systems

    NASA Astrophysics Data System (ADS)

    Letertre, Thierry; Monebhurrun, Vikass; Toffano, Zeno

    2013-04-01

    Isotropic broadband probes or spectrum analyzers (SAs) may be used for the measurement of rapidly varying electromagnetic fields generated by emerging wireless communication systems. In this paper this problematic is investigated by comparing the responses measured by two different isotropic broadband probes typically used to perform electric field (E-field) evaluations. The broadband probes are submitted to signals with variable duty cycles (DC) and crest factors (CF) either with or without Orthogonal Frequency Division Multiplexing (OFDM) modulation but with the same root-mean-square (RMS) power. The two probes do not provide accurate enough results for deterministic signals such as Worldwide Interoperability for Microwave Access (WIMAX) or Long Term Evolution (LTE) as well as for non-deterministic signals such as Wireless Fidelity (WiFi). The legacy measurement protocols should be adapted to cope for the emerging wireless communication technologies based on the OFDM modulation scheme. This is not easily achieved except when the statistics of the RF emission are well known. In this case the measurement errors are shown to be systematic and a correction factor or calibration can be applied to obtain a good approximation of the total RMS power.

  2. Accurate measure by weight of liquids in industry

    SciTech Connect

    Muller, M.R.

    1992-12-12

    This research's focus was to build a prototype of a computerized liquid dispensing system. This liquid metering system is based on the concept of altering the representative volume to account for temperature changes in the liquid to be dispensed. This is actualized by using a measuring tank and a temperature compensating displacement plunger. By constantly monitoring the temperature of the liquid, the plunger can be used to increase or decrease the specified volume to more accurately dispense liquid with a specified mass. In order to put the device being developed into proper engineering perspective, an extensive literature review was undertaken on all areas of industrial metering of liquids with an emphasis on gravimetric methods.

  3. Accurate measure by weight of liquids in industry. Final report

    SciTech Connect

    Muller, M.R.

    1992-12-12

    This research`s focus was to build a prototype of a computerized liquid dispensing system. This liquid metering system is based on the concept of altering the representative volume to account for temperature changes in the liquid to be dispensed. This is actualized by using a measuring tank and a temperature compensating displacement plunger. By constantly monitoring the temperature of the liquid, the plunger can be used to increase or decrease the specified volume to more accurately dispense liquid with a specified mass. In order to put the device being developed into proper engineering perspective, an extensive literature review was undertaken on all areas of industrial metering of liquids with an emphasis on gravimetric methods.

  4. Method for Accurate Surface Temperature Measurements During Fast Induction Heating

    NASA Astrophysics Data System (ADS)

    Larregain, Benjamin; Vanderesse, Nicolas; Bridier, Florent; Bocher, Philippe; Arkinson, Patrick

    2013-07-01

    A robust method is proposed for the measurement of surface temperature fields during induction heating. It is based on the original coupling of temperature-indicating lacquers and a high-speed camera system. Image analysis tools have been implemented to automatically extract the temporal evolution of isotherms. This method was applied to the fast induction treatment of a 4340 steel spur gear, allowing the full history of surface isotherms to be accurately documented for a sequential heating, i.e., a medium frequency preheating followed by a high frequency final heating. Three isotherms, i.e., 704, 816, and 927°C, were acquired every 0.3 ms with a spatial resolution of 0.04 mm per pixel. The information provided by the method is described and discussed. Finally, the transformation temperature Ac1 is linked to the temperature on specific locations of the gear tooth.

  5. Electron Microprobe Analysis Techniques for Accurate Measurements of Apatite

    NASA Astrophysics Data System (ADS)

    Goldoff, B. A.; Webster, J. D.; Harlov, D. E.

    2010-12-01

    Apatite [Ca5(PO4)3(F, Cl, OH)] is a ubiquitous accessory mineral in igneous, metamorphic, and sedimentary rocks. The mineral contains halogens and hydroxyl ions, which can provide important constraints on fugacities of volatile components in fluids and other phases in igneous and metamorphic environments in which apatite has equilibrated. Accurate measurements of these components in apatite are therefore necessary. Analyzing apatite by electron microprobe (EMPA), which is a commonly used geochemical analytical technique, has often been found to be problematic and previous studies have identified sources of error. For example, Stormer et al. (1993) demonstrated that the orientation of an apatite grain relative to the incident electron beam could significantly affect the concentration results. In this study, a variety of alternative EMPA operating conditions for apatite analysis were investigated: a range of electron beam settings, count times, crystal grain orientations, and calibration standards were tested. Twenty synthetic anhydrous apatite samples that span the fluorapatite-chlorapatite solid solution series, and whose halogen concentrations were determined by wet chemistry, were analyzed. Accurate measurements of these samples were obtained with many EMPA techniques. One effective method includes setting a static electron beam to 10-15nA, 15kV, and 10 microns in diameter. Additionally, the apatite sample is oriented with the crystal’s c-axis parallel to the slide surface and the count times are moderate. Importantly, the F and Cl EMPA concentrations are in extremely good agreement with the wet-chemical data. We also present EMPA operating conditions and techniques that are problematic and should be avoided. J.C. Stormer, Jr. et al., Am. Mineral. 78 (1993) 641-648.

  6. Accurate measurement of liquid transport through nanoscale conduits

    PubMed Central

    Alibakhshi, Mohammad Amin; Xie, Quan; Li, Yinxiao; Duan, Chuanhua

    2016-01-01

    Nanoscale liquid transport governs the behaviour of a wide range of nanofluidic systems, yet remains poorly characterized and understood due to the enormous hydraulic resistance associated with the nanoconfinement and the resulting minuscule flow rates in such systems. To overcome this problem, here we present a new measurement technique based on capillary flow and a novel hybrid nanochannel design and use it to measure water transport through single 2-D hydrophilic silica nanochannels with heights down to 7 nm. Our results show that silica nanochannels exhibit increased mass flow resistance compared to the classical hydrodynamics prediction. This difference increases with decreasing channel height and reaches 45% in the case of 7 nm nanochannels. This resistance increase is attributed to the formation of a 7-angstrom-thick stagnant hydration layer on the hydrophilic surfaces. By avoiding use of any pressure and flow sensors or any theoretical estimations the hybrid nanochannel scheme enables facile and precise flow measurement through single nanochannels, nanotubes, or nanoporous media and opens the prospect for accurate characterization of both hydrophilic and hydrophobic nanofluidic systems. PMID:27112404

  7. ELODIE: A spectrograph for accurate radial velocity measurements.

    NASA Astrophysics Data System (ADS)

    Baranne, A.; Queloz, D.; Mayor, M.; Adrianzyk, G.; Knispel, G.; Kohler, D.; Lacroix, D.; Meunier, J.-P.; Rimbaud, G.; Vin, A.

    1996-10-01

    The fibre-fed echelle spectrograph of Observatoire de Haute-Provence, ELODIE, is presented. This instrument has been in operation since the end of 1993 on the 1.93 m telescope. ELODIE is designed as an updated version of the cross-correlation spectrometer CORAVEL, to perform very accurate radial velocity measurements such as needed in the search, by Doppler shift, for brown-dwarfs or giant planets orbiting around nearby stars. In one single exposure a spectrum at a resolution of 42000 (λ/{DELTA}λ) ranging from 3906A to 6811A is recorded on a 1024x1024 CCD. This performance is achieved by using a tanθ=4 echelle grating and a combination of a prism and a grism as cross-disperser. An automatic on-line data treatment reduces all the ELODIE echelle spectra and computes cross-correlation functions. The instrument design and the data reduction algorithms are described in this paper. The efficiency and accuracy of the instrument and its long term instrumental stability allow us to measure radial velocities with an accuracy better than 15m/s for stars up to 9th magnitude in less than 30 minutes exposure time. Observations of 16th magnitude stars are also possible to measure velocities at about 1km/s accuracy. For classic spectroscopic studies (S/N>100) 9th magnitude stars can be observed in one hour exposure time.

  8. Radio Astronomers Set New Standard for Accurate Cosmic Distance Measurement

    NASA Astrophysics Data System (ADS)

    1999-06-01

    A team of radio astronomers has used the National Science Foundation's Very Long Baseline Array (VLBA) to make the most accurate measurement ever made of the distance to a faraway galaxy. Their direct measurement calls into question the precision of distance determinations made by other techniques, including those announced last week by a team using the Hubble Space Telescope. The radio astronomers measured a distance of 23.5 million light-years to a galaxy called NGC 4258 in Ursa Major. "Ours is a direct measurement, using geometry, and is independent of all other methods of determining cosmic distances," said Jim Herrnstein, of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. The team says their measurement is accurate to within less than a million light-years, or four percent. The galaxy is also known as Messier 106 and is visible with amateur telescopes. Herrnstein, along with James Moran and Lincoln Greenhill of the Harvard- Smithsonian Center for Astrophysics; Phillip Diamond, of the Merlin radio telescope facility at Jodrell Bank and the University of Manchester in England; Makato Inoue and Naomasa Nakai of Japan's Nobeyama Radio Observatory; Mikato Miyoshi of Japan's National Astronomical Observatory; Christian Henkel of Germany's Max Planck Institute for Radio Astronomy; and Adam Riess of the University of California at Berkeley, announced their findings at the American Astronomical Society's meeting in Chicago. "This is an incredible achievement to measure the distance to another galaxy with this precision," said Miller Goss, NRAO's Director of VLA/VLBA Operations. "This is the first time such a great distance has been measured this accurately. It took painstaking work on the part of the observing team, and it took a radio telescope the size of the Earth -- the VLBA -- to make it possible," Goss said. "Astronomers have sought to determine the Hubble Constant, the rate of expansion of the universe, for decades. This will in turn lead to an

  9. Accurate measurement of psoralen-crosslinked DNA: direct biochemical measurements and indirect measurement by hybridization

    SciTech Connect

    Matsuo, N.; Ross, P.M.

    1988-11-01

    This paper evaluates methods to measure crosslinkage due to psoralen plus light in total DNA and in specific sequences. DNA exposed in cells or in vitro to a bifunctional psoralen and near ultraviolet light accumulates interstrand crosslinks. Crosslinkage is the DNA mass fraction that is attached in both strands to a crosslink. We show here biochemical methods to measure psoralen photocrosslinkage accurately in total DNA. We also describe methods to measure photocrosslinkage indirectly, in specific sequences, by nucleic acid hybridization. We show that a single 4,5',8-trimethylpsoralen (TMP) crosslink causes at least 50 kbp of alkali-denatured DNA contiguous in both strands with it to snap back into the duplex form when the denatured preparation is returned to neutral pH. This process was so efficient that the DNA was not nicked by the single-strand nuclease S1 at 100-fold excess after snapping back. Uncrosslinked DNA was digested to acid-soluble material by the enzyme. Crosslinkage therefore equals the fraction of S1-resistant nucleotide in this kind of experiment. We alkali-denatured DNA samples crosslinked to varying degrees by varying TMP concentration at constant light exposure. We then measured crosslinkage by ethidium bromide (EtBr) fluorometry at pH 11.8; by EtBr fluorometry at neutral pH of S1 digests of the DNA; and by the fraction of radioactivity remaining acid insoluble in S1-digests of DNA labeled uniformly with (3H)deoxythymidine. These assays measure distinct physical properties of crosslinked DNA. Numerical agreement is expected only when all three measurements are accurate. Under optimum conditions, the three methods yielded identical results over the range of measurement. Using alkaline EtBr fluorescence in crude cell lysates, we detected crosslinks at frequencies in the range of 1.6 X 10(-7) per base pair.

  10. Estimation of bone permeability using accurate microstructural measurements.

    PubMed

    Beno, Thoma; Yoon, Young-June; Cowin, Stephen C; Fritton, Susannah P

    2006-01-01

    While interstitial fluid flow is necessary for the viability of osteocytes, it is also believed to play a role in bone's mechanosensory system by shearing bone cell membranes or causing cytoskeleton deformation and thus activating biochemical responses that lead to the process of bone adaptation. However, the fluid flow properties that regulate bone's adaptive response are poorly understood. In this paper, we present an analytical approach to determine the degree of anisotropy of the permeability of the lacunar-canalicular porosity in bone. First, we estimate the total number of canaliculi emanating from each osteocyte lacuna based on published measurements from parallel-fibered shaft bones of several species (chick, rabbit, bovine, horse, dog, and human). Next, we determine the local three-dimensional permeability of the lacunar-canalicular porosity for these species using recent microstructural measurements and adapting a previously developed model. Results demonstrated that the number of canaliculi per osteocyte lacuna ranged from 41 for human to 115 for horse. Permeability coefficients were found to be different in three local principal directions, indicating local orthotropic symmetry of bone permeability in parallel-fibered cortical bone for all species examined. For the range of parameters investigated, the local lacunar-canalicular permeability varied more than three orders of magnitude, with the osteocyte lacunar shape and size along with the 3-D canalicular distribution determining the degree of anisotropy of the local permeability. This two-step theoretical approach to determine the degree of anisotropy of the permeability of the lacunar-canalicular porosity will be useful for accurate quantification of interstitial fluid movement in bone.

  11. Automatic classification and accurate size measurement of blank mask defects

    NASA Astrophysics Data System (ADS)

    Bhamidipati, Samir; Paninjath, Sankaranarayanan; Pereira, Mark; Buck, Peter

    2015-07-01

    complexity of defects encountered. The variety arises due to factors such as defect nature, size, shape and composition; and the optical phenomena occurring around the defect. This paper focuses on preliminary characterization results, in terms of classification and size estimation, obtained by Calibre MDPAutoClassify tool on a variety of mask blank defects. It primarily highlights the challenges faced in achieving the results with reference to the variety of defects observed on blank mask substrates and the underlying complexities which make accurate defect size measurement an important and challenging task.

  12. Fast processing techniques for accurate ultrasonic range measurements

    NASA Astrophysics Data System (ADS)

    Barshan, Billur

    2000-01-01

    Four methods of range measurement for airborne ultrasonic systems - namely simple thresholding, curve-fitting, sliding-window, and correlation detection - are compared on the basis of bias error, standard deviation, total error, robustness to noise, and the difficulty/complexity of implementation. Whereas correlation detection is theoretically optimal, the other three methods can offer acceptable performance at much lower cost. Performances of all methods have been investigated as a function of target range, azimuth, and signal-to-noise ratio. Curve fitting, sliding window, and thresholding follow correlation detection in the order of decreasing complexity. Apart from correlation detection, minimum bias and total error is most consistently obtained with the curve-fitting method. On the other hand, the sliding-window method is always better than the thresholding and curve-fitting methods in terms of minimizing the standard deviation. The experimental results are in close agreement with the corresponding simulation results. Overall, the three simple and fast processing methods provide a variety of attractive compromises between measurement accuracy and system complexity. Although this paper concentrates on ultrasonic range measurement in air, the techniques described may also find application in underwater acoustics.

  13. Numerical assessment of accurate measurements of laminar flame speed

    NASA Astrophysics Data System (ADS)

    Goulier, Joules; Bizon, Katarzyna; Chaumeix, Nabiha; Meynet, Nicolas; Continillo, Gaetano

    2016-12-01

    In combustion, the laminar flame speed constitutes an important parameter that reflects the chemistry of oxidation for a given fuel, along with its transport and thermal properties. Laminar flame speeds are used (i) in turbulent models used in CFD codes, and (ii) to validate detailed or reduced mechanisms, often derived from studies using ideal reactors and in diluted conditions as in jet stirred reactors and in shock tubes. End-users of such mechanisms need to have an assessment of their capability to predict the correct heat released by combustion in realistic conditions. In this view, the laminar flame speed constitutes a very convenient parameter, and it is then very important to have a good knowledge of the experimental errors involved with its determination. Stationary configurations (Bunsen burners, counter-flow flames, heat flux burners) or moving flames (tubes, spherical vessel, soap bubble) can be used. The spherical expanding flame configuration has recently become popular, since it can be used at high pressures and temperatures. With this method, the flame speed is not measured directly, but derived through the recording of the flame radius. The method used to process the radius history will have an impact on the estimated flame speed. Aim of this work is to propose a way to derive the laminar flame speed from experimental recording of expanding flames, and to assess the error magnitude.

  14. Accurate body composition measures from whole-body silhouettes

    PubMed Central

    Xie, Bowen; Avila, Jesus I.; Ng, Bennett K.; Fan, Bo; Loo, Victoria; Gilsanz, Vicente; Hangartner, Thomas; Kalkwarf, Heidi J.; Lappe, Joan; Oberfield, Sharon; Winer, Karen; Zemel, Babette; Shepherd, John A.

    2015-01-01

    Purpose: Obesity and its consequences, such as diabetes, are global health issues that burden about 171 × 106 adult individuals worldwide. Fat mass index (FMI, kg/m2), fat-free mass index (FFMI, kg/m2), and percent fat mass may be useful to evaluate under- and overnutrition and muscle development in a clinical or research environment. This proof-of-concept study tested whether frontal whole-body silhouettes could be used to accurately measure body composition parameters using active shape modeling (ASM) techniques. Methods: Binary shape images (silhouettes) were generated from the skin outline of dual-energy x-ray absorptiometry (DXA) whole-body scans of 200 healthy children of ages from 6 to 16 yr. The silhouette shape variation from the average was described using an ASM, which computed principal components for unique modes of shape. Predictive models were derived from the modes for FMI, FFMI, and percent fat using stepwise linear regression. The models were compared to simple models using demographics alone [age, sex, height, weight, and body mass index z-scores (BMIZ)]. Results: The authors found that 95% of the shape variation of the sampled population could be explained using 26 modes. In most cases, the body composition variables could be predicted similarly between demographics-only and shape-only models. However, the combination of shape with demographics improved all estimates of boys and girls compared to the demographics-only model. The best prediction models for FMI, FFMI, and percent fat agreed with the actual measures with R2 adj. (the coefficient of determination adjusted for the number of parameters used in the model equation) values of 0.86, 0.95, and 0.75 for boys and 0.90, 0.89, and 0.69 for girls, respectively. Conclusions: Whole-body silhouettes in children may be useful to derive estimates of body composition including FMI, FFMI, and percent fat. These results support the feasibility of measuring body composition variables from simple

  15. Accurate measurement of the specific absorption rate using a suitable adiabatic magnetothermal setup

    NASA Astrophysics Data System (ADS)

    Natividad, Eva; Castro, Miguel; Mediano, Arturo

    2008-03-01

    Accurate measurements of the specific absorption rate (SAR) of solids and fluids were obtained by a calorimetric method, using a special-purpose setup working under adiabatic conditions. Unlike in current nonadiabatic setups, the weak heat exchange with the surroundings allowed a straightforward determination of temperature increments, avoiding the usual initial-time approximations. The measurements performed on a commercial magnetite aqueous ferrofluid revealed a good reproducibility (4%). Also, the measurements on a copper sample allowed comparison between experimental and theoretical values: adiabatic conditions gave SAR values only 3% higher than the theoretical ones, while the typical nonadiabatic method underestimated SAR by 21%.

  16. Accurate potential drop sheet resistance measurements of laser-doped areas in semiconductors

    SciTech Connect

    Heinrich, Martin; Kluska, Sven; Binder, Sebastian; Hameiri, Ziv; Hoex, Bram; Aberle, Armin G.

    2014-10-07

    It is investigated how potential drop sheet resistance measurements of areas formed by laser-assisted doping in crystalline Si wafers are affected by typically occurring experimental factors like sample size, inhomogeneities, surface roughness, or coatings. Measurements are obtained with a collinear four point probe setup and a modified transfer length measurement setup to measure sheet resistances of laser-doped lines. Inhomogeneities in doping depth are observed from scanning electron microscope images and electron beam induced current measurements. It is observed that influences from sample size, inhomogeneities, surface roughness, and coatings can be neglected if certain preconditions are met. Guidelines are given on how to obtain accurate potential drop sheet resistance measurements on laser-doped regions.

  17. Accurate mass replacement method for the sediment concentration measurement with a constant volume container

    NASA Astrophysics Data System (ADS)

    Ban, Yunyun; Chen, Tianqin; Yan, Jun; Lei, Tingwu

    2017-04-01

    The measurement of sediment concentration in water is of great importance in soil erosion research and soil and water loss monitoring systems. The traditional weighing method has long been the foundation of all the other measuring methods and instrument calibration. The development of a new method to replace the traditional oven-drying method is of interest in research and practice for the quick and efficient measurement of sediment concentration, especially field measurements. A new method is advanced in this study for accurately measuring the sediment concentration based on the accurate measurement of the mass of the sediment-water mixture in the confined constant volume container (CVC). A sediment-laden water sample is put into the CVC to determine its mass before the CVC is filled with water and weighed again for the total mass of the water and sediments in the container. The known volume of the CVC, the mass of sediment-laden water, and sediment particle density are used to calculate the mass of water, which is replaced by sediments, therefore sediment concentration of the sample is calculated. The influence of water temperature was corrected by measuring water density to determine the temperature of water before measurements were conducted. The CVC was used to eliminate the surface tension effect so as to obtain the accurate volume of water and sediment mixture. Experimental results showed that the method was capable of measuring the sediment concentration from 0.5 up to 1200 kg m‑3. A good liner relationship existed between the designed and measured sediment concentrations with all the coefficients of determination greater than 0.999 and the averaged relative error less than 0.2%. All of these seem to indicate that the new method is capable of measuring a full range of sediment concentration above 0.5 kg m‑3 to replace the traditional oven-drying method as a standard method for evaluating and calibrating other methods.

  18. Approach to accurately measuring the speed of optical precursors

    SciTech Connect

    Li Chuanfeng; Zhou Zongquan; Guo Guangcan; Jeong, Heejeong

    2011-10-15

    Precursors can serve as a bound on the speed of information with dispersive medium. We propose a method to identify the speed of optical wave fronts using polarization-based interference in a solid-state device, which can bound the accuracy of the speed of wave fronts to less than 10{sup -4} with conventional experimental conditions. Our proposal may have important implications for optical communications and fast information processing.

  19. Method accurately measures mean particle diameters of monodisperse polystyrene latexes

    NASA Technical Reports Server (NTRS)

    Kubitschek, H. E.

    1967-01-01

    Photomicrographic method determines mean particle diameters of monodisperse polystyrene latexes. Many diameters are measured simultaneously by measuring row lengths of particles in a triangular array at a glass-oil interface. The method provides size standards for electronic particle counters and prevents distortions, softening, and flattening.

  20. Accurate Measurements of Spectral Reflectance in Picasso's Guernica Painting.

    PubMed

    de Luna, Javier Muñoz; Fernandez-Balbuena, Antonio Alvarez; Vázquez, Daniel; Melgosa, Manuel; Durán, Humberto; García, Jorge; Muro, Carmen

    2016-01-01

    The use of non-invasive spectral measurements to control the conservation status is a part of the preventive conservation of artworks which nowadays is becoming increasingly interesting. This paper describes how to use a spectral measuring device and an illumination system specifically designed for such a task in a very large dimension artwork painting (7.8 m wide × 3.5 m high). The system, controlled by a Cartesian robot, allows spectral measurements in a spectral range of 400-780 nm. The measured data array has a total of 2201 circular regions with 5.5 mm spot diameter placed on a square grid. Colorimetric calculations performed from these spectral measurements may be used to characterize color shifts related to reflectance changes in specific areas of the paint. A color shifting from the expected gray has been shown.

  1. Accurate surface tension measurement of glass melts by the pendant drop method.

    PubMed

    Chang, Yao-Yuan; Wu, Ming-Ya; Hung, Yi-Lin; Lin, Shi-Yow

    2011-05-01

    A pendant drop tensiometer, coupled with image digitization technology and a best-fitting algorithm, was built to accurately measure the surface tension of glass melts at high temperatures. More than one thousand edge-coordinate points were obtained for a pendant glass drop. These edge points were fitted with the theoretical drop profiles derived from the Young-Laplace equation to determine the surface tension of glass melt. The uncertainty of the surface tension measurements was investigated. The measurement uncertainty (σ) could be related to a newly defined factor of drop profile completeness (Fc): the larger the Fc is, the smaller σ is. Experimental data showed that the uncertainty of the surface tension measurement when using this pendant drop tensiometer could be ±3 mN∕m for glass melts.

  2. PRESAGE 3D dosimetry accurately measures Gamma Knife output factors

    NASA Astrophysics Data System (ADS)

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-12-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and 2D detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ±0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors.

  3. Accurate aircraft wind measurements using the global positioning system (GPS)

    SciTech Connect

    Dobosy, R.J.; Crawford, T.L., McMillen, R.T., Dumas, E.J.

    1996-11-01

    High accuracy measurements of the spatial distribution of wind speed are required in the study of turbulent exchange between the atmosphere and the earth. The use of a differential global positioning system (GPS) to determine the sensor velocity vector component of wind speed is discussed in this paper. The results of noise and rocking testing are summarized, and fluxes obtained from the GPS-based methods are compared to those measured from systems on towers and airplanes. The GPS-based methods provided usable measurements that compared well with tower and aircraft data at a significantly lower cost. 21 refs., 1 fig., 2 tabs.

  4. Magnetic field models of nine CP stars from "accurate" measurements

    NASA Astrophysics Data System (ADS)

    Glagolevskij, Yu. V.

    2013-01-01

    The dipole models of magnetic fields in nine CP stars are constructed based on the measurements of metal lines taken from the literature, and performed by the LSD method with an accuracy of 10-80 G. The model parameters are compared with the parameters obtained for the same stars from the hydrogen line measurements. For six out of nine stars the same type of structure was obtained. Some parameters, such as the field strength at the poles B p and the average surface magnetic field B s differ considerably in some stars due to differences in the amplitudes of phase dependences B e (Φ) and B s (Φ), obtained by different authors. It is noted that a significant increase in the measurement accuracy has little effect on the modelling of the large-scale structures of the field. By contrast, it is more important to construct the shape of the phase dependence based on a fairly large number of field measurements, evenly distributed by the rotation period phases. It is concluded that the Zeeman component measurement methods have a strong effect on the shape of the phase dependence, and that the measurements of the magnetic field based on the lines of hydrogen are more preferable for modelling the large-scale structures of the field.

  5. Apparatus designed for very accurate measurement of the optical reflection.

    PubMed

    Piombini, Hervé; Voarino, Philippe

    2007-12-20

    The described instrument is a new reflectometer designed to check the normal specular reflectance of 40,000 reflectors necessary for the Laser Megajoule (LMJ). This new reflectometer has a high accuracy over the 400-950 nm wavelength range and allows the delicate measurement of shaped parts. The measurements are relative and several reference mirrors, which are low loss dielectric mirrors [R(lambda)>99.9%], are used for the standardization. The apparatus gives an excellent repeatability (< 0.06% at 2sigma) thanks to its design and automatic focalization imaging system. After a brief review that is related to performance evolution of the spectrophotometers, our facility and its components are described. The methodology of focusing and calibration are explained. The capabilities of our device are illustrated through some measurements realized on flat or shaped samples.

  6. How accurately can suborbital experiments measure the CMB?

    SciTech Connect

    Oliveira-Costa, Angelica de; Tegmark, Max; Devlin, Mark J.; Page, Lyman; Miller, Amber D.; Netterfield, C. Barth; Xu Yongzhong

    2005-02-15

    Great efforts are currently being channeled into ground- and balloon-based CMB experiments, mainly to explore polarization and anisotropy on small angular scales. To optimize instrumental design and assess experimental prospects, it is important to understand in detail the atmosphere-related systematic errors that limit the science achievable with new instruments. As a step in this direction, we spatially compare the 648 square degree ground- and balloon-based QMASK map with the atmosphere-free WMAP map, finding beautiful agreement on all angular scales where both are sensitive. Although much work remains on quantifying atmospheric effects on CMB experiments, this is a reassuring quantitative assessment of the power of the state-of-the-art fast-Fourier-transform- and matrix-based mapmaking techniques that have been used for QMASK and virtually all subsequent experiments.

  7. Accurate measurement of gas volumes by liquid displacement

    NASA Technical Reports Server (NTRS)

    Christian, J. D.

    1972-01-01

    Mariotte bottle as liquid displacement device was used to measure gas volumes at flow rates that are far below threshold of wet test gas meters. Study of factors affecting amount of liquid displaced by gas flow was completed, and equations were derived which relate different variables.

  8. Air toxics being measured more accurately, controlled more effectively

    SciTech Connect

    1995-04-01

    In response to the directives of the Clean Air Act Amendments, Argonne National Laboratory is developing new or improved pollutant control technologies for industries that burn fossil fuels. This research continues Argonne`s traditional support for the US DOE Flue Gas Cleanup Program. Research is underway to measure process emissions and identify new and improved control measures. Argonne`s emission control research has ranged from experiments in the basic chemistry of pollution-control systems, through laboratory-scale process development and testing to pilot-scale field tests of several technologies. Whenever appropriate, the work has emphasized integrated or combined control systems as the best approach to technologies that offer low cost and good operating characteristics.

  9. Accurate reconstruction in measurement of microstructures using digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolei; Zhang, Xiangchao; Xiao, Hong; Xu, Min

    2016-11-01

    Due to the limitation of traditional interferometry, digital holographic microscopy has attracted intensive attention for its capability of measuring complex shapes. However, speckles are inevitable in the recorded interferometric patterns, thereby polluting the reconstructed surface topographies. In this paper, a phase-shifting interferometer is built to realize the in-axis digital holographic microscopy. The anti-aliasing shift-invariant contourlet transform (ASCT) is used for reconstructing the measured surfaces. By avoiding subsampling in the scale and directional filtering schemes, the problems of frequency aliasing and phase distortion can be effectively solved. Practical experiments show that speckles can be recognized and removed straightforwardly. Therefore the proposed method has excellent performance for reconstructing structured surfaces.

  10. Accurate Measurement of Heat Capacity by Differential Scanning Calorimetry

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Experience with high quality heat capacity measurement by differential scanning calorimetry is summarized and illustrated, pointing out three major causes of error: (1) incompatible thermal histories of the sample, reference and blank runs; (2) unstable initial and final isotherms; (3) incompatible differences between initial and final isotherm amplitudes for sample, reference and blank runs. Considering these problems, it is shown for the case of polyoxymethylene that accuracies in heat capacity of 0.1 percent may be possible.

  11. ACCURATE TEMPERATURE MEASUREMENTS IN A NATURALLY-ASPIRATED RADIATION SHIELD

    SciTech Connect

    Kurzeja, R.

    2009-09-09

    Experiments and calculations were conducted with a 0.13 mm fine wire thermocouple within a naturally-aspirated Gill radiation shield to assess and improve the accuracy of air temperature measurements without the use of mechanical aspiration, wind speed or radiation measurements. It was found that this thermocouple measured the air temperature with root-mean-square errors of 0.35 K within the Gill shield without correction. A linear temperature correction was evaluated based on the difference between the interior plate and thermocouple temperatures. This correction was found to be relatively insensitive to shield design and yielded an error of 0.16 K for combined day and night observations. The correction was reliable in the daytime when the wind speed usually exceeds 1 m s{sup -1} but occasionally performed poorly at night during very light winds. Inspection of the standard deviation in the thermocouple wire temperature identified these periods but did not unambiguously locate the most serious events. However, estimates of sensor accuracy during these periods is complicated by the much larger sampling volume of the mechanically-aspirated sensor compared with the naturally-aspirated sensor and the presence of significant near surface temperature gradients. The root-mean-square errors therefore are upper limits to the aspiration error since they include intrinsic sensor differences and intermittent volume sampling differences.

  12. Model verification studies using accurate measurements of spin up

    NASA Technical Reports Server (NTRS)

    Hyun, J. M.

    1981-01-01

    The reliability and accuracy of the numerical code for spin up flows in a cylinder by comparing the numerical results against high resolution laser Doppler velocimeter (LDV) measurements of the azimuthal flows were checked. A computer code to generate numerical solution for axisymmetric rotating fluid in a cylinder was obtained and amended for routine use at MSFC. The numerical simulations used the Navier-Stokes equations in axisymmetric form and employed finite difference techniques on both constant and variable grids. The numerical solutions are analyzed to gain further insight into the fundamental questions analyzed in rotating fluid dynamics.

  13. Accurate measurement of mean sea level changes by altimetric satellites

    NASA Technical Reports Server (NTRS)

    Born, G. H.; Tapley, B. D.; Ries, J. C.; Stewart, R. H.

    1986-01-01

    A technique for monitoring changes in global mean sea levels using altimeter data from a well-tracked satellite is examined. The usefulness of this technique is evaluated by analyzing Seasat altimeter data obtained during July-September 1978. The effects of orbit errors, geoid errors, sampling intervals, tides, and atmosphere refraction on the calculation of the mean sea level are investigated. The data reveal that the stability of an altimeter can be determined with an accuracy of + or - 7 cm using globally averaged sea surface height measurements. The application of this procedure to the US/French Ocean Topography Experiment is discussed.

  14. Diamond micro-Raman thermometers for accurate gate temperature measurements

    SciTech Connect

    Simon, Roland B.; Pomeroy, James W.; Kuball, Martin

    2014-05-26

    Determining the peak channel temperature in AlGaN/GaN high electron mobility transistors and other devices with high accuracy is an important and challenging issue. A surface-sensitive thermometric technique is demonstrated, utilizing Raman thermography and diamond microparticles to measure the gate temperature. This technique enhances peak channel temperature estimation, especially when it is applied in combination with standard micro-Raman thermography. Its application to other metal-covered areas of devices, such as field plates is demonstrated. Furthermore, this technique can be readily applied to other material/device systems.

  15. Accurate measurement of curvilinear shapes by Virtual Image Correlation

    NASA Astrophysics Data System (ADS)

    Semin, B.; Auradou, H.; François, M. L. M.

    2011-10-01

    The proposed method allows the detection and the measurement, in the sense of metrology, of smooth elongated curvilinear shapes. Such measurements are required in many fields of physics, for example: mechanical engineering, biology or medicine (deflection of beams, fibers or filaments), fluid mechanics or chemistry (detection of fronts). Contrary to actual methods, the result is given in an analytical form of class C∞ (and not a finite set of locations or pixels) thus curvatures and slopes, often of great interest in science, are given with good confidence. The proposed Virtual Image Correlation (VIC) method uses a virtual beam, an image which consists in a lateral expansion of the curve with a bell-shaped gray level. This figure is deformed until it fits the best the physical image with a method issued from the Digital Image Correlation method in use in solid mechanics. The precision of the identification is studied in a benchmark and successfully compared to two state-of-the-art methods. Three practical examples are given: a bar bending under its own weight, a thin fiber transported by a flow within a fracture and a thermal front. The first allows a comparison with theoretical solution, the second shows the ability of the method to deal with complex shapes and crossings and the third deals with ill-defined image.

  16. Knowledge of accurate blood pressure measurement procedures in chiropractic students

    PubMed Central

    Crosley, Angela M.; Rose, James R. La

    2013-01-01

    Objective Blood pressure measurement is a basic clinical procedure. However, studies have shown that many errors are made when health care providers acquire blood pressure readings. Our study assessed knowledge of blood pressure measurement procedures in chiropractic students. Methods This was an observational, descriptive study. A questionnaire based on one created by the American Heart Association was given to 1st, 2nd, 3rd, and final year students (n = 186). A one way ANOVA was used to analyze the data. Results Of the students 80% were confident that their knowledge of this clinical skill was adequate or better. However, the overall score on the knowledge test of blood pressure–taking skills was 52% (range, 24%–88%). The only significant difference in the mean scores was between the 1st and 2nd year students compared to the 3rd and 4th year students (p < .005). Of the 16 questions given, the following mean scores were: 1st year 10.45, 2nd year 9.75, 3rd year 7.93, and 4th year 8.33. Of the 16 areas tested, 10 were of major concern (test item score <70%), showing the need for frequent retraining of chiropractic students. Conclusion Consistent with studies in other health care disciplines, our research found the knowledge of blood pressure skills to be deficient in our sample. There is a need for subsequent training in our teaching program. PMID:23957320

  17. Fast and accurate automated measurements in digitized stereophotogrammetric radiographs.

    PubMed

    Vrooman, H A; Valstar, E R; Brand, G J; Admiraal, D R; Rozing, P M; Reiber, J H

    1998-05-01

    Until recently, Roentgen Stereophotogrammetric Analysis (RSA) required the manual definition of all markers using a high-resolution measurement table. To automate this tedious and time-consuming process and to eliminate observer variabilities, an analytical software package has been developed and validated for the detection, identification, and matching of markers in RSA radiographs. The digital analysis procedure consisted of the following steps: (1) the detection of markers using a variant of the Hough circle-finder technique; (2) the identification and labeling of the detected markers; (3) the reconstruction of the three-dimensional position of the bone markers and the prosthetic markers; and (4) the computation of micromotion. To assess the influence of film digitization, the measurements obtained from nine phantom radiographs using two different film scanners were compared with the results obtained by manual processing. All markers in the phantom radiographs were automatically detected and correctly labeled. The best results were obtained with a Vidar VXR-12 CCD scanner, for which the measurement errors were comparable to the errors associated with the manual approach. To assess the in vivo reproducibility, 30 patient radiographs were analyzed twice with the manual as well as with the automated procedure. Approximately, 85% of all calibration markers and bone markers were automatically detected and correctly matched. The calibration errors and the rigid-body errors show that the accuracy of the automated procedure is comparable to the accuracy of the manual procedure. The rigid-body errors had comparable mean values for both techniques: 0.05 mm for the tibia and 0.06 mm for the prosthesis. The reproducibility of the automated procedure showed to be slightly better than that of the manual procedure. The maximum errors in the computed translation and rotation of the tibial component were 0.11 mm and 0.24, compared to 0.13 mm and 0.27 for the manual RSA procedure

  18. Particle Image Velocimetry Measurements in Anatomically-Accurate Models of the Mammalian Nasal Cavity

    NASA Astrophysics Data System (ADS)

    Rumple, C.; Richter, J.; Craven, B. A.; Krane, M.

    2012-11-01

    A summary of the research being carried out by our multidisciplinary team to better understand the form and function of the nose in different mammalian species that include humans, carnivores, ungulates, rodents, and marine animals will be presented. The mammalian nose houses a convoluted airway labyrinth, where two hallmark features of mammals occur, endothermy and olfaction. Because of the complexity of the nasal cavity, the anatomy and function of these upper airways remain poorly understood in most mammals. However, recent advances in high-resolution medical imaging, computational modeling, and experimental flow measurement techniques are now permitting the study of airflow and respiratory and olfactory transport phenomena in anatomically-accurate reconstructions of the nasal cavity. Here, we focus on efforts to manufacture transparent, anatomically-accurate models for stereo particle image velocimetry (SPIV) measurements of nasal airflow. Challenges in the design and manufacture of index-matched anatomical models are addressed and preliminary SPIV measurements are presented. Such measurements will constitute a validation database for concurrent computational fluid dynamics (CFD) simulations of mammalian respiration and olfaction. Supported by the National Science Foundation.

  19. An Approach for the Accurate Measurement of Social Morality Levels

    PubMed Central

    Liu, Haiyan; Chen, Xia; Zhang, Bo

    2013-01-01

    In the social sciences, computer-based modeling has become an increasingly important tool receiving widespread attention. However, the derivation of the quantitative relationships linking individual moral behavior and social morality levels, so as to provide a useful basis for social policy-making, remains a challenge in the scholarly literature today. A quantitative measurement of morality from the perspective of complexity science constitutes an innovative attempt. Based on the NetLogo platform, this article examines the effect of various factors on social morality levels, using agents modeling moral behavior, immoral behavior, and a range of environmental social resources. Threshold values for the various parameters are obtained through sensitivity analysis; and practical solutions are proposed for reversing declines in social morality levels. The results show that: (1) Population size may accelerate or impede the speed with which immoral behavior comes to determine the overall level of social morality, but it has no effect on the level of social morality itself; (2) The impact of rewards and punishment on social morality levels follows the “5∶1 rewards-to-punishment rule,” which is to say that 5 units of rewards have the same effect as 1 unit of punishment; (3) The abundance of public resources is inversely related to the level of social morality; (4) When the cost of population mobility reaches 10% of the total energy level, immoral behavior begins to be suppressed (i.e. the 1/10 moral cost rule). The research approach and methods presented in this paper successfully address the difficulties involved in measuring social morality levels, and promise extensive application potentials. PMID:24312189

  20. Device for accurately measuring mass flow of gases

    DOEpatents

    Hylton, J.O.; Remenyik, C.J.

    1994-08-09

    A device for measuring mass flow of gases which utilizes a substantially buoyant pressure vessel suspended within a fluid/liquid in an enclosure is disclosed. The pressure vessel is connected to a weighing device for continuously determining weight change of the vessel as a function of the amount of gas within the pressure vessel. In the preferred embodiment, this pressure vessel is formed from inner and outer right circular cylindrical hulls, with a volume between the hulls being vented to the atmosphere external the enclosure. The fluid/liquid, normally in the form of water typically with an added detergent, is contained within an enclosure with the fluid/liquid being at a level such that the pressure vessel is suspended beneath this level but above a bottom of the enclosure. The buoyant pressure vessel can be interconnected with selected valves to an auxiliary pressure vessel so that initial flow can be established to or from the auxiliary pressure vessel prior to flow to or from the buoyant pressure vessel. 5 figs.

  1. Device for accurately measuring mass flow of gases

    DOEpatents

    Hylton, James O.; Remenyik, Carl J.

    1994-01-01

    A device for measuring mass flow of gases which utilizes a substantially buoyant pressure vessel suspended within a fluid/liquid in an enclosure. The pressure vessel is connected to a weighing device for continuously determining weight change of the vessel as a function of the amount of gas within the pressure vessel. In the preferred embodiment, this pressure vessel is formed from inner and outer right circular cylindrical hulls, with a volume between the hulls being vented to the atmosphere external the enclosure. The fluid/liquid, normally in the form of water typically with an added detergent, is contained within an enclosure with the fluid/liquid being at a level such that the pressure vessel is suspended beneath this level but above a bottom of the enclosure. The buoyant pressure vessel can be interconnected with selected valves to an auxiliary pressure vessel so that initial flow can be established to or from the auxiliary pressure vessel prior to flow to or from the buoyant pressure vessel.

  2. Importance of Accurate Measurements in Nutrition Research: Dietary Flavonoids as a Case Study1234

    PubMed Central

    Harnly, James

    2016-01-01

    Accurate measurements of the secondary metabolites in natural products and plant foods are critical for establishing relations between diet and health. There are as many as 50,000 secondary metabolites that may influence human health. Their structural and chemical diversity presents a challenge to analytical chemistry. With respect to flavonoids, putative identification is accessible, but positive identification and quantification are limited by the lack of standards. Quantification has been tested with use of both nonspecific and specific methods. Nonspecific methods, which include antioxidant capacity methods, fail to provide information on the measured components, suffer from numerous interferences, are not equatable, and are unsuitable for health research. Specific methods, such as LC with diode array and mass spectrometric detection, require the use of internal standards and relative molar response factors. These methods are relatively expensive and require a high level of expertise and experimental verification; however, they represent the only suitable means of relating health outcomes to specific dietary components. PMID:26980821

  3. Importance of Accurate Measurements in Nutrition Research: Dietary Flavonoids as a Case Study.

    PubMed

    Harnly, James

    2016-03-01

    Accurate measurements of the secondary metabolites in natural products and plant foods are critical for establishing relations between diet and health. There are as many as 50,000 secondary metabolites that may influence human health. Their structural and chemical diversity presents a challenge to analytical chemistry. With respect to flavonoids, putative identification is accessible, but positive identification and quantification are limited by the lack of standards. Quantification has been tested with use of both nonspecific and specific methods. Nonspecific methods, which include antioxidant capacity methods, fail to provide information on the measured components, suffer from numerous interferences, are not equatable, and are unsuitable for health research. Specific methods, such as LC with diode array and mass spectrometric detection, require the use of internal standards and relative molar response factors. These methods are relatively expensive and require a high level of expertise and experimental verification; however, they represent the only suitable means of relating health outcomes to specific dietary components.

  4. Multiple-frequency continuous wave ultrasonic system for accurate distance measurement

    NASA Astrophysics Data System (ADS)

    Huang, C. F.; Young, M. S.; Li, Y. C.

    1999-02-01

    A highly accurate multiple-frequency continuous wave ultrasonic range-measuring system for use in air is described. The proposed system uses a method heretofore applied to radio frequency distance measurement but not to air-based ultrasonic systems. The method presented here is based upon the comparative phase shifts generated by three continuous ultrasonic waves of different but closely spaced frequencies. In the test embodiment to confirm concept feasibility, two low cost 40 kHz ultrasonic transducers are set face to face and used to transmit and receive ultrasound. Individual frequencies are transmitted serially, each generating its own phase shift. For any given frequency, the transmitter/receiver distance modulates the phase shift between the transmitted and received signals. Comparison of the phase shifts allows a highly accurate evaluation of target distance. A single-chip microcomputer-based multiple-frequency continuous wave generator and phase detector was designed to record and compute the phase shift information and the resulting distance, which is then sent to either a LCD or a PC. The PC is necessary only for calibration of the system, which can be run independently after calibration. Experiments were conducted to test the performance of the whole system. Experimentally, ranging accuracy was found to be within ±0.05 mm, with a range of over 1.5 m. The main advantages of this ultrasonic range measurement system are high resolution, low cost, narrow bandwidth requirements, and ease of implementation.

  5. Extracting accurate strain measurements in bone mechanics: A critical review of current methods.

    PubMed

    Grassi, Lorenzo; Isaksson, Hanna

    2015-10-01

    Osteoporosis related fractures are a social burden that advocates for more accurate fracture prediction methods. Mechanistic methods, e.g. finite element models, have been proposed as a tool to better predict bone mechanical behaviour and strength. However, there is little consensus about the optimal constitutive law to describe bone as a material. Extracting reliable and relevant strain data from experimental tests is of fundamental importance to better understand bone mechanical properties, and to validate numerical models. Several techniques have been used to measure strain in experimental mechanics, with substantial differences in terms of accuracy, precision, time- and length-scale. Each technique presents upsides and downsides that must be carefully evaluated when designing the experiment. Moreover, additional complexities are often encountered when applying such strain measurement techniques to bone, due to its complex composite structure. This review of literature examined the four most commonly adopted methods for strain measurements (strain gauges, fibre Bragg grating sensors, digital image correlation, and digital volume correlation), with a focus on studies with bone as a substrate material, at the organ and tissue level. For each of them the working principles, a summary of the main applications to bone mechanics at the organ- and tissue-level, and a list of pros and cons are provided.

  6. An accurate air temperature measurement system based on an envelope pulsed ultrasonic time-of-flight technique

    NASA Astrophysics Data System (ADS)

    Huang, Y. S.; Huang, Y. P.; Huang, K. N.; Young, M. S.

    2007-11-01

    A new microcomputer based air temperature measurement system is presented. An accurate temperature measurement is derived from the measurement of sound velocity by using an ultrasonic time-of-flight (TOF) technique. The study proposes a novel algorithm that combines both amplitude modulation (AM) and phase modulation (PM) to get the TOF measurement. The proposed system uses the AM and PM envelope square waveform (APESW) to reduce the error caused by inertia delay. The APESW ultrasonic driving waveform causes an envelope zero and phase inversion phenomenon in the relative waveform of the receiver. To accurately achieve a TOF measurement, the phase inversion phenomenon was used to sufficiently identify the measurement pulse in the received waveform. Additionally, a counter clock technique was combined to compute the phase shifts of the last incomplete cycle for TOF. The presented system can obtain 0.1% TOF resolution for the period corresponding to the 40kHz frequency ultrasonic wave. Consequently, with the integration of a humidity compensation algorithm, a highly accurate and high resolution temperature measurement can be achieved using the accurate TOF measurement. Experimental results indicate that the combined standard uncertainty of the temperature measurement is approximately 0.39°C. The main advantages of this system are high resolution measurements, narrow bandwidth requirements, and ease of implementation.

  7. Measuring nonlinear oscillations using a very accurate and low-cost linear optical position transducer

    NASA Astrophysics Data System (ADS)

    Donoso, Guillermo; Ladera, Celso L.

    2016-09-01

    An accurate linear optical displacement transducer of about 0.2 mm resolution over a range of ∼40 mm is presented. This device consists of a stack of thin cellulose acetate strips, each strip longitudinally slid ∼0.5 mm over the precedent one so that one end of the stack becomes a stepped wedge of constant step. A narrowed light beam from a white LED orthogonally incident crosses the wedge at a known point, the transmitted intensity being detected with a phototransistor whose emitter is connected to a diode. We present the interesting analytical proof that the voltage across the diode is linearly dependent upon the ordinate of the point where the light beam falls on the wedge, as well as the experimental validation of such a theoretical proof. Applications to nonlinear oscillations are then presented—including the interesting case of a body moving under dry friction, and the more advanced case of an oscillator in a quartic energy potential—whose time-varying positions were accurately measured with our transducer. Our sensing device can resolve the dynamics of an object attached to it with great accuracy and precision at a cost considerably less than that of a linear neutral density wedge. The technique used to assemble the wedge of acetate strips is described.

  8. Accurate rotational constants for linear interstellar carbon chains: achieving experimental accuracy

    NASA Astrophysics Data System (ADS)

    Etim, Emmanuel E.; Arunan, Elangannan

    2017-01-01

    Linear carbon chain molecular species remain the dominant theme in interstellar chemistry. Their continuous astronomical observation depends on the availability of accurate spectroscopic parameters. Accurate rotational constants are reported for hundreds of molecular species of astrophysical, spectroscopy and chemical interests from the different linear carbon chains; C_{{n}}H, C_{{n}}H-, C_{{n}}N, C_{{n}}N-, C_{{n}}O, C_{{n}}S, HC_{{n}}S, C_{{n}}Si, CH3(CC)_{{n}}H, HC_{{n}}N, DC_{2{n}+1}N, HC_{2{n}}NC, and CH3(C≡C)_{{n}}CN using three to four moments of inertia calculated from the experimental rotational constants coupled with those obtained from the optimized geometries at the Hartree Fock level. The calculated rotational constants are obtained from the corrected moments of inertia at the Hartfree Fock geometries. The calculated rotational constants show accuracy of few kHz below irrespective of the chain length and terminating groups. The obtained accuracy of few kHz places these rotational constants as excellent tools for both astronomical and laboratory detection of these molecular species of astrophysical interest. From the numerous unidentified lines from different astronomical surveys, transitions corresponding to known and new linear carbon chains could be found using these rotational constants. The astrophysical, spectroscopic and chemical implications of these results are discussed.

  9. Identification and Evaluation of Reference Genes for Accurate Transcription Normalization in Safflower under Different Experimental Conditions

    PubMed Central

    Li, Dandan; Hu, Bo; Wang, Qing; Liu, Hongchang; Pan, Feng; Wu, Wei

    2015-01-01

    Safflower (Carthamus tinctorius L.) has received a significant amount of attention as a medicinal plant and oilseed crop. Gene expression studies provide a theoretical molecular biology foundation for improving new traits and developing new cultivars. Real-time quantitative PCR (RT-qPCR) has become a crucial approach for gene expression analysis. In addition, appropriate reference genes (RGs) are essential for accurate and rapid relative quantification analysis of gene expression. In this study, fifteen candidate RGs involved in multiple metabolic pathways of plants were finally selected and validated under different experimental treatments, at different seed development stages and in different cultivars and tissues for real-time PCR experiments. These genes were ABCS, 60SRPL10, RANBP1, UBCL, MFC, UBCE2, EIF5A, COA, EF1-β, EF1, GAPDH, ATPS, MBF1, GTPB and GST. The suitability evaluation was executed by the geNorm and NormFinder programs. Overall, EF1, UBCE2, EIF5A, ATPS and 60SRPL10 were the most stable genes, and MBF1, as well as MFC, were the most unstable genes by geNorm and NormFinder software in all experimental samples. To verify the validation of RGs selected by the two programs, the expression analysis of 7 CtFAD2 genes in safflower seeds at different developmental stages under cold stress was executed using different RGs in RT-qPCR experiments for normalization. The results showed similar expression patterns when the most stable RGs selected by geNorm or NormFinder software were used. However, the differences were detected using the most unstable reference genes. The most stable combination of genes selected in this study will help to achieve more accurate and reliable results in a wide variety of samples in safflower. PMID:26457898

  10. Material response mechanisms are needed to obtain highly accurate experimental shock wave data

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry W.

    2017-01-01

    The field of shock wave compression of matter has provided a simple set of equations relating thermodynamic and kinematic parameters that describe the conservation of mass, momentum and energy across a steady plane shock wave with one-dimensional flow. Well-known condensed matter shock wave experimental results will be reviewed to see whether the assumptions required for deriving these simple R-H equations are satisfied. Note that the material compression model is not required for deriving the 1-D conservation flow equations across a steady plane shock front. However, this statement is misleading from a practical experimental viewpoint since obtaining small systematic errors in shock wave measured parameters requires the material compression and release mechanisms to be known. A review will be presented on errors in shock wave data from common experimental techniques for elastic-plastic solids. Issues related to time scales of experiments, steady waves with long rise times and detonations will also be discussed

  11. An Accurate Method for Measuring Airplane-Borne Conformal Antenna's Radar Cross Section

    NASA Astrophysics Data System (ADS)

    Guo, Shuxia; Zhang, Lei; Wang, Yafeng; Hu, Chufeng

    2016-09-01

    The airplane-borne conformal antenna attaches itself tightly with the airplane skin, so the conventional measurement method cannot determine the contribution of the airplane-borne conformal antenna to its radar cross section (RCS). This paper uses the 2D microwave imaging to isolate and extract the distribution of the reflectivity of the airplane-borne conformal antenna. It obtains the 2D spatial spectra of the conformal antenna through the wave spectral transform between the 2D spatial image and the 2D spatial spectrum. After the interpolation from the rectangular coordinate domain to the polar coordinate domain, the spectral domain data for the variation of the scatter of the conformal antenna with frequency and angle is obtained. The experimental results show that the measurement method proposed in this paper greatly enhances the airplane-borne conformal antenna's RCS measurement accuracy, essentially eliminates the influences caused by the airplane skin and more accurately reveals the airplane-borne conformal antenna's RCS scatter properties.

  12. An accurate optical technique for measuring the nuclear polarisation of 3He gas

    NASA Astrophysics Data System (ADS)

    Talbot, C.; Batz, M.; Nacher, P.-J.; Tastevin, G.

    2011-06-01

    In the metastability exchange optical pumping cells of our on-site production unit and of our other experimental set-ups, we use a light absorption technique to measure the 3He nuclear polarisation. It involves weak probe beams at 1083 nm, that are either perpendicular or parallel to the magnetic field and cell axis, with suitable light polarisations. When metastability exchange collisions control the populations of the sublevels in the 23S state, absolute values of the 3He ground state nuclear polarisation are directly inferred from the ratio of the absorption rates measured for these probe beams. Our report focuses on the transverse detection scheme for which this ratio, measured at low magnetic field for σ and π light polarisations, hardly depends on gas pressure or the presence of an intense pump beam. This technique has been systematically tested both in pure 3He and isotopic mixtures and it is routinely used for accurate control of the optical pumping efficiency as well as for calibration of the NMR system.

  13. A cost-effective transparency-based digital imaging for efficient and accurate wound area measurement.

    PubMed

    Li, Pei-Nan; Li, Hong; Wu, Mo-Li; Wang, Shou-Yu; Kong, Qing-You; Zhang, Zhen; Sun, Yuan; Liu, Jia; Lv, De-Cheng

    2012-01-01

    Wound measurement is an objective and direct way to trace the course of wound healing and to evaluate therapeutic efficacy. Nevertheless, the accuracy and efficiency of the current measurement methods need to be improved. Taking the advantages of reliability of transparency tracing and the accuracy of computer-aided digital imaging, a transparency-based digital imaging approach is established, by which data from 340 wound tracing were collected from 6 experimental groups (8 rats/group) at 8 experimental time points (Day 1, 3, 5, 7, 10, 12, 14 and 16) and orderly archived onto a transparency model sheet. This sheet was scanned and its image was saved in JPG form. Since a set of standard area units from 1 mm(2) to 1 cm(2) was integrated into the sheet, the tracing areas in JPG image were measured directly, using the "Magnetic lasso tool" in Adobe Photoshop program. The pixel values/PVs of individual outlined regions were obtained and recorded in an average speed of 27 second/region. All PV data were saved in an excel form and their corresponding areas were calculated simultaneously by the formula of Y (PV of the outlined region)/X (PV of standard area unit) × Z (area of standard unit). It took a researcher less than 3 hours to finish area calculation of 340 regions. In contrast, over 3 hours were expended by three skillful researchers to accomplish the above work with traditional transparency-based method. Moreover, unlike the results obtained traditionally, little variation was found among the data calculated by different persons and the standard area units in different sizes and shapes. Given its accurate, reproductive and efficient properties, this transparency-based digital imaging approach would be of significant values in basic wound healing research and clinical practice.

  14. Is scintillometer measurement accurate enough for evaluating remote sensing based energy balance ET models?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The three evapotranspiration (ET) measurement/retrieval techniques used in this study, lysimeter, scintillometer and remote sensing vary in their level of complexity, accuracy, resolution and applicability. The lysimeter with its point measurement is the most accurate and direct method to measure ET...

  15. Wear characteristics of UHMW polyethylene: a method for accurately measuring extremely low wear rates.

    PubMed

    McKellop, H; Clarke, I C; Markolf, K L; Amstutz, H C

    1978-11-01

    The wear of UHMW polyethylene bearing against 316 stainless steel or cobalt chrome alloy was measured using a 12-channel wear tester especially developed for the evaluation of candidate materials for prosthetic joints. The coefficient of friction and wear rate was determined as a function of lubricant, contact stress, and metallic surface roughness in tests lasting two to three million cycles, the equivalent of several years' use of a prosthesis. Wear was determined from the weight loss of the polyethylene specimens corrected for the effect of fluid absorption. The friction and wear processes in blood serum differed markedly from those in saline solution or distilled water. Only serum lubrication produced wear surfaces resembling those observed on removed prostheses. The experimental method provided a very accurate reproducible measurement of polyethylene wear. The long-term wear rates were proportional to load and sliding distance and were much lower than expected from previously published data. Although the polyethylene wear rate increased with increasing surface roughness, wear was not severe except with very coarse metal surfaces. The data obtained in these studies forms a basis for the subsequent comparative evaluation of potentially superior materials for prosthetic joints.

  16. MASS MEASUREMENTS BY AN ACCURATE AND SENSITIVE SELECTED ION RECORDING TECHNIQUE

    EPA Science Inventory

    Trace-level components of mixtures were successfully identified or confirmed by mass spectrometric accurate mass measurements, made at high resolution with selected ion recording, using GC and LC sample introduction. Measurements were made at 20 000 or 10 000 resolution, respecti...

  17. Measuring laser power as a force: a new paradigm to accurately monitor optical power during laser-based machining operations

    NASA Astrophysics Data System (ADS)

    Williams, Paul; Simonds, Brian; Sowards, Jeffrey; Hadler, Joshua

    2016-03-01

    In laser manufacturing operations, accurate measurement of laser power is important for product quality, operational repeatability, and process validation. Accurate real-time measurement of high-power lasers, however, is difficult. Typical thermal power meters must absorb all the laser power in order to measure it. This constrains power meters to be large, slow and exclusive (that is, the laser cannot be used for its intended purpose during the measurement). To address these limitations, we have developed a different paradigm in laser power measurement where the power is not measured according to its thermal equivalent but rather by measuring the laser beam's momentum (radiation pressure). Very simply, light reflecting from a mirror imparts a small force perpendicular to the mirror which is proportional to the optical power. By mounting a high-reflectivity mirror on a high-sensitivity force transducer (scale), we are able to measure laser power in the range of tens of watts up to ~ 100 kW. The critical parameters for such a device are mirror reflectivity, angle of incidence, and scale sensitivity and accuracy. We will describe our experimental characterization of a radiation-pressure-based optical power meter. We have tested it for modulated and CW laser powers up to 92 kW in the laboratory and up to 20 kW in an experimental laser welding booth. We will describe present accuracy, temporal response, sources of measurement uncertainty, and hurdles which must be overcome to have an accurate power meter capable of routine operation as a turning mirror within a laser delivery head.

  18. Accurate measurements of the acoustical physical constants of synthetic alpha-quartz for SAW devices.

    PubMed

    Kushibiki, Juin-ichi; Takanaga, Izumi; Nishiyama, Shouichi

    2002-01-01

    Accurate measurements of the acoustical physical constants (elastic constants, piezoelectric constants, dielectric constants, and density) of commercially available and widely used surface acoustic wave (SAW)-grade synthetic a-quartz are reported. The propagation directions and modes of bulk waves optimal for accurately determining the constants were selected through numerical calculations, and three principal X-, Y-, and Z-cut specimens and several rotated Y-cut specimens were prepared from a single crystal ingot to determine the constants and to confirm their accuracy. All of the constants were determined through highly accurate measurements of the longitudinal velocities, shear velocities, dielectric constants, and density. The velocity values measured for the specimens that were not used to determine the constants agreed well with those calculated from the determined constants, within a difference of +/- 0.20 m/s (+/- 0.004%).

  19. Recent Results on the Accurate Measurements of the Dielectric Constant of Seawater at 1.413GHZ

    NASA Technical Reports Server (NTRS)

    Lang, R.H.; Tarkocin, Y.; Utku, C.; Le Vine, D.M.

    2008-01-01

    Measurements of the complex. dielectric constant of seawater at 30.00 psu, 35.00 psu and 38.27 psu over the temperature range from 5 C to 3 5 at 1.413 GHz are given and compared with the Klein-Swift results. A resonant cavity technique is used. The calibration constant used in the cavity perturbation formulas is determined experimentally using methanol and ethanediol (ethylene glycol) as reference liquids. Analysis of the data shows that the measurements are accurate to better than 1.0% in almost all cases studied.

  20. An X-band waveguide measurement technique for the accurate characterization of materials with low dielectric loss permittivity

    NASA Astrophysics Data System (ADS)

    Allen, Kenneth W.; Scott, Mark M.; Reid, David R.; Bean, Jeffrey A.; Ellis, Jeremy D.; Morris, Andrew P.; Marsh, Jeramy M.

    2016-05-01

    In this work, we present a new X-band waveguide (WR90) measurement method that permits the broadband characterization of the complex permittivity for low dielectric loss tangent material specimens with improved accuracy. An electrically long polypropylene specimen that partially fills the cross-section is inserted into the waveguide and the transmitted scattering parameter (S21) is measured. The extraction method relies on computational electromagnetic simulations, coupled with a genetic algorithm, to match the experimental S21 measurement. The sensitivity of the technique to sample length was explored by simulating specimen lengths from 2.54 to 15.24 cm, in 2.54 cm increments. Analysis of our simulated data predicts the technique will have the sensitivity to measure loss tangent values on the order of 10-3 for materials such as polymers with relatively low real permittivity values. The ability to accurately characterize low-loss dielectric material specimens of polypropylene is demonstrated experimentally. The method was validated by excellent agreement with a free-space focused-beam system measurement of a polypropylene sheet. This technique provides the material measurement community with the ability to accurately extract material properties of low-loss material specimen over the entire X-band range. This technique could easily be extended to other frequency bands.

  1. Accurate respiration measurement using DC-coupled continuous-wave radar sensor for motion-adaptive cancer radiotherapy.

    PubMed

    Gu, Changzhan; Li, Ruijiang; Zhang, Hualiang; Fung, Albert Y C; Torres, Carlos; Jiang, Steve B; Li, Changzhi

    2012-11-01

    Accurate respiration measurement is crucial in motion-adaptive cancer radiotherapy. Conventional methods for respiration measurement are undesirable because they are either invasive to the patient or do not have sufficient accuracy. In addition, measurement of external respiration signal based on conventional approaches requires close patient contact to the physical device which often causes patient discomfort and undesirable motion during radiation dose delivery. In this paper, a dc-coupled continuous-wave radar sensor was presented to provide a noncontact and noninvasive approach for respiration measurement. The radar sensor was designed with dc-coupled adaptive tuning architectures that include RF coarse-tuning and baseband fine-tuning, which allows the radar sensor to precisely measure movement with stationary moment and always work with the maximum dynamic range. The accuracy of respiration measurement with the proposed radar sensor was experimentally evaluated using a physical phantom, human subject, and moving plate in a radiotherapy environment. It was shown that respiration measurement with radar sensor while the radiation beam is on is feasible and the measurement has a submillimeter accuracy when compared with a commercial respiration monitoring system which requires patient contact. The proposed radar sensor provides accurate, noninvasive, and noncontact respiration measurement and therefore has a great potential in motion-adaptive radiotherapy.

  2. Importance of Accurate Measurements in Nutrition Research: Dietary Flavonoids as a Case Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate measurements of the secondary metabolites in natural products and plant foods are critical to establishing diet/health relationships. There are as many as 50,000 secondary metabolites which may influence human health. Their structural and chemical diversity present a challenge to analytic...

  3. Accurate measurement method of Fabry-Perot cavity parameters via optical transfer function

    SciTech Connect

    Bondu, Francois; Debieu, Olivier

    2007-05-10

    It is shown how the transfer function from frequency noise to a Pound-Drever-Hall signal for a Fabry-Perot cavity can be used to accurately measure cavity length, cavity linewidth, mirror curvature, misalignments, laser beam shape mismatching with resonant beam shape, and cavity impedance mismatching with respect to vacuum.

  4. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... production and utilization? 3275.15 Section 3275.15 Public Lands: Interior Regulations Relating to Public...) GEOTHERMAL RESOURCE LEASING Conducting Utilization Operations § 3275.15 How accurately must I measure my production and utilization? It depends on whether you use a meter to calculate Federal production or...

  5. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... production and utilization? 3275.15 Section 3275.15 Public Lands: Interior Regulations Relating to Public...) GEOTHERMAL RESOURCE LEASING Conducting Utilization Operations § 3275.15 How accurately must I measure my production and utilization? It depends on whether you use a meter to calculate Federal production or...

  6. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... production and utilization? 3275.15 Section 3275.15 Public Lands: Interior Regulations Relating to Public...) GEOTHERMAL RESOURCE LEASING Conducting Utilization Operations § 3275.15 How accurately must I measure my production and utilization? It depends on whether you use a meter to calculate Federal production or...

  7. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, C.V.; Killian, E.W.; Grafwallner, E.G.; Kynaston, R.L.; Johnson, L.O.; Randolph, P.D.

    1996-09-03

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector. 7 figs.

  8. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, Charles V.; Killian, E. Wayne; Grafwallner, Ervin G.; Kynaston, Ronnie L.; Johnson, Larry O.; Randolph, Peter D.

    1996-01-01

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector.

  9. Development and experimental verification of a finite element method for accurate analysis of a surface acoustic wave device

    NASA Astrophysics Data System (ADS)

    Mohibul Kabir, K. M.; Matthews, Glenn I.; Sabri, Ylias M.; Russo, Salvy P.; Ippolito, Samuel J.; Bhargava, Suresh K.

    2016-03-01

    Accurate analysis of surface acoustic wave (SAW) devices is highly important due to their use in ever-growing applications in electronics, telecommunication and chemical sensing. In this study, a novel approach for analyzing the SAW devices was developed based on a series of two-dimensional finite element method (FEM) simulations, which has been experimentally verified. It was found that the frequency response of the two SAW device structures, each having slightly different bandwidth and center lobe characteristics, can be successfully obtained utilizing the current density of the electrodes via FEM simulations. The two SAW structures were based on XY Lithium Niobate (LiNbO3) substrates and had two and four electrode finger pairs in both of their interdigital transducers, respectively. Later, SAW devices were fabricated in accordance with the simulated models and their measured frequency responses were found to correlate well with the obtained simulations results. The results indicated that better match between calculated and measured frequency response can be obtained when one of the input electrode finger pairs was set at zero volts and all the current density components were taken into account when calculating the frequency response of the simulated SAW device structures.

  10. Techniques for determining propulsion system forces for accurate high speed vehicle drag measurements in flight

    NASA Technical Reports Server (NTRS)

    Arnaiz, H. H.

    1975-01-01

    As part of a NASA program to evaluate current methods of predicting the performance of large, supersonic airplanes, the drag of the XB-70 airplane was measured accurately in flight at Mach numbers from 0.75 to 2.5. This paper describes the techniques used to determine engine net thrust and the drag forces charged to the propulsion system that were required for the in-flight drag measurements. The accuracy of the measurements and the application of the measurement techniques to aircraft with different propulsion systems are discussed. Examples of results obtained for the XB-70 airplane are presented.

  11. Defining allowable physical property variations for high accurate measurements on polymer parts

    NASA Astrophysics Data System (ADS)

    Mohammadi, A.; Sonne, M. R.; Madruga, D. G.; De Chiffre, L.; Hattel, J. H.

    2016-06-01

    Measurement conditions and material properties have a significant impact on the dimensions of a part, especially for polymers parts. Temperature variation causes part deformations that increase the uncertainty of the measurement process. Current industrial tolerances of a few micrometres demand high accurate measurements in non-controlled ambient. Most of polymer parts are manufactured by injection moulding and their inspection is carried out after stabilization, around 200 hours. The overall goal of this work is to reach ±5μm in uncertainty measurements a polymer products which is a challenge in today`s production and metrology environments. The residual deformations in polymer products at room temperature after injection molding are important when micrometer accuracy needs to be achieved. Numerical modelling can give a valuable insight to what is happening in the polymer during cooling down after injection molding. In order to obtain accurate simulations, accurate inputs to the model are crucial. In reality however, the material and physical properties will have some variations. Although these variations may be small, they can act as a source of uncertainty for the measurement. In this paper, we investigated how big the variation in material and physical properties are allowed in order to reach the 5 μm target on the uncertainty.

  12. Use of an inertial navigation system for accurate track recovery and coastal oceanographic measurements

    NASA Technical Reports Server (NTRS)

    Oliver, B. M.; Gower, J. F. R.

    1977-01-01

    A data acquisition system using a Litton LTN-51 inertial navigation unit (INU) was tested and used for aircraft track recovery and for location and tracking from the air of targets at sea. The characteristic position drift of the INU is compensated for by sighting landmarks of accurately known position at discrete time intervals using a visual sighting system in the transparent nose of the Beechcraft 18 aircraft used. For an aircraft altitude of about 300 m, theoretical and experimental tests indicate that calculated aircraft and/or target positions obtained from the interpolated INU drift curve will be accurate to within 10 m for landmarks spaced approximately every 15 minutes in time. For applications in coastal oceanography, such as surface current mapping by tracking artificial targets, the system allows a broad area to be covered without use of high altitude photography and its attendant needs for large targets and clear weather.

  13. System to measure accurate temperature dependence of electric conductivity down to 20 K in ultrahigh vacuum.

    PubMed

    Sakai, C; Takeda, S N; Daimon, H

    2013-07-01

    We have developed the new in situ electrical-conductivity measurement system which can be operated in ultrahigh vacuum (UHV) with accurate temperature measurement down to 20 K. This system is mainly composed of a new sample-holder fixing mechanism, a new movable conductivity-measurement mechanism, a cryostat, and two receptors for sample- and four-probe holders. Sample-holder is pushed strongly against the receptor, which is connected to a cryostat, by using this new sample-holder fixing mechanism to obtain high thermal conductivity. Test pieces on the sample-holders have been cooled down to about 20 K using this fixing mechanism, although they were cooled down to only about 60 K without this mechanism. Four probes are able to be touched to a sample surface using this new movable conductivity-measurement mechanism for measuring electrical conductivity after making film on substrates or obtaining clean surfaces by cleavage, flashing, and so on. Accurate temperature measurement is possible since the sample can be transferred with a thermocouple and∕or diode being attached directly to the sample. A single crystal of Bi-based copper oxide high-Tc superconductor (HTSC) was cleaved in UHV to obtain clean surface, and its superconducting critical temperature has been successfully measured in situ. The importance of in situ measurement of resistance in UHV was demonstrated for this HTSC before and after cesium (Cs) adsorption on its surface. The Tc onset increase and the Tc offset decrease by Cs adsorption were observed.

  14. Photoacoustic spectrometer for accurate, continuous measurements of atmospheric carbon dioxide concentration

    NASA Astrophysics Data System (ADS)

    Reed, Zachary D.; Sperling, Brent; van Zee, Roger D.; Whetstone, James R.; Gillis, Keith A.; Hodges, Joseph T.

    2014-06-01

    We have developed a portable photoacoustic spectrometer that offers routine, precise and accurate measurements of the molar concentration of atmospheric carbon. The temperature-controlled spectrometer continuously samples dried atmospheric air and employs an intensity-modulated distributed feedback laser and fiber amplifier operating near 1.57 µm. For measurements of carbon dioxide in air, we demonstrate a measurement precision (60-s averaging time) of 0.15 µmol mol-1 and achieve a standard uncertainty of 0.8 µmol mol-1 by calibrating the analyzer response in terms of certified gas mixtures. We also investigate how water vapor affects the photoacoustic signal by promoting collisional relaxation of the carbon dioxide.

  15. Progress Toward Accurate Measurements of Power Consumptions of DBD Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Ashpis, David E.; Laun, Matthew C.; Griebeler, Elmer L.

    2012-01-01

    The accurate measurement of power consumption by Dielectric Barrier Discharge (DBD) plasma actuators is a challenge due to the characteristics of the actuator current signal. Micro-discharges generate high-amplitude, high-frequency current spike transients superimposed on a low-amplitude, low-frequency current. We have used a high-speed digital oscilloscope to measure the actuator power consumption using the Shunt Resistor method and the Monitor Capacitor method. The measurements were performed simultaneously and compared to each other in a time-accurate manner. It was found that low signal-to-noise ratios of the oscilloscopes used, in combination with the high dynamic range of the current spikes, make the Shunt Resistor method inaccurate. An innovative, nonlinear signal compression circuit was applied to the actuator current signal and yielded excellent agreement between the two methods. The paper describes the issues and challenges associated with performing accurate power measurements. It provides insights into the two methods including new insight into the Lissajous curve of the Monitor Capacitor method. Extension to a broad range of parameters and further development of the compression hardware will be performed in future work.

  16. Accurate microfour-point probe sheet resistance measurements on small samples.

    PubMed

    Thorsteinsson, Sune; Wang, Fei; Petersen, Dirch H; Hansen, Torben Mikael; Kjaer, Daniel; Lin, Rong; Kim, Jang-Yong; Nielsen, Peter F; Hansen, Ole

    2009-05-01

    We show that accurate sheet resistance measurements on small samples may be performed using microfour-point probes without applying correction factors. Using dual configuration measurements, the sheet resistance may be extracted with high accuracy when the microfour-point probes are in proximity of a mirror plane on small samples with dimensions of a few times the probe pitch. We calculate theoretically the size of the "sweet spot," where sufficiently accurate sheet resistances result and show that even for very small samples it is feasible to do correction free extraction of the sheet resistance with sufficient accuracy. As an example, the sheet resistance of a 40 microm (50 microm) square sample may be characterized with an accuracy of 0.3% (0.1%) using a 10 microm pitch microfour-point probe and assuming a probe alignment accuracy of +/-2.5 microm.

  17. Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers.

    PubMed

    Hattne, Johan; Echols, Nathaniel; Tran, Rosalie; Kern, Jan; Gildea, Richard J; Brewster, Aaron S; Alonso-Mori, Roberto; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G; Lassalle-Kaiser, Benedikt; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R; Miahnahri, Alan; White, William E; Schafer, Donald W; Seibert, M Marvin; Koglin, Jason E; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J; Glatzel, Pieter; Zwart, Petrus H; Grosse-Kunstleve, Ralf W; Bogan, Michael J; Messerschmidt, Marc; Williams, Garth J; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Yano, Junko; Bergmann, Uwe; Yachandra, Vittal K; Adams, Paul D; Sauter, Nicholas K

    2014-05-01

    X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and without radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract meaningful high-resolution signals from fewer diffraction measurements.

  18. A Novel Multimode Waveguide Coupler for Accurate Power Measurement of Traveling Wave Tube Harmonic Frequencies

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.; Simons, Rainee N.

    2014-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from two dissimilar waveguides is capable of isolating the power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT). In addition to accurate power measurements at harmonic frequencies, a potential application of the MDC is in the design of a beacon source for atmospheric propagation studies at millimeter-wave frequencies.

  19. High-precision topography measurement through accurate in-focus plane detection with hybrid digital holographic microscope and white light interferometer module.

    PubMed

    Liżewski, Kamil; Tomczewski, Sławomir; Kozacki, Tomasz; Kostencka, Julianna

    2014-04-10

    High-precision topography measurement of micro-objects using interferometric and holographic techniques can be realized provided that the in-focus plane of an imaging system is very accurately determined. Therefore, in this paper we propose an accurate technique for in-focus plane determination, which is based on coherent and incoherent light. The proposed method consists of two major steps. First, a calibration of the imaging system with an amplitude object is performed with a common autofocusing method using coherent illumination, which allows for accurate localization of the in-focus plane position. In the second step, the position of the detected in-focus plane with respect to the imaging system is measured with white light interferometry. The obtained distance is used to accurately adjust a sample with the precision required for the measurement. The experimental validation of the proposed method is given for measurement of high-numerical-aperture microlenses with subwavelength accuracy.

  20. Accurate phase measurements for thick spherical objects using optical quadrature microscopy

    NASA Astrophysics Data System (ADS)

    Warger, William C., II; DiMarzio, Charles A.

    2009-02-01

    In vitro fertilization (IVF) procedures have resulted in the birth of over three million babies since 1978. Yet the live birth rate in the United States was only 34% in 2005, with 32% of the successful pregnancies resulting in multiple births. These multiple pregnancies were directly attributed to the transfer of multiple embryos to increase the probability that a single, healthy embryo was included. Current viability markers used for IVF, such as the cell number, symmetry, size, and fragmentation, are analyzed qualitatively with differential interference contrast (DIC) microscopy. However, this method is not ideal for quantitative measures beyond the 8-cell stage of development because the cells overlap and obstruct the view within and below the cluster of cells. We have developed the phase-subtraction cell-counting method that uses the combination of DIC and optical quadrature microscopy (OQM) to count the number of cells accurately in live mouse embryos beyond the 8-cell stage. We have also created a preliminary analysis to measure the cell symmetry, size, and fragmentation quantitatively by analyzing the relative dry mass from the OQM image in conjunction with the phase-subtraction count. In this paper, we will discuss the characterization of OQM with respect to measuring the phase accurately for spherical samples that are much larger than the depth of field. Once fully characterized and verified with human embryos, this methodology could provide the means for a more accurate method to score embryo viability.

  1. Accurate measurement of spatial noise portraits of photosensors of digital cameras

    NASA Astrophysics Data System (ADS)

    Cheremkhin, P. A.; Evtikhiev, N. N.; Krasnov, V. V.; Kulakov, M. N.; Starikov, R. S.

    2016-08-01

    Method of measurement of accurate portraits of light and dark spatial noise of photosensors is described. The method consists of four steps: creation of spatially homogeneous illumination; shooting light and dark frames; digital processing and filtering. Unlike standard technique, this method uses iterative creation of spatially homogeneous illumination by display, compensation of photosensor dark spatial noise portrait and improved procedure of elimination of dark temporal noise. Portraits of light and dark spatial noise of photosensors of a scientific digital camera were found. Characteristics of the measured portraits were compared with values of photo response and dark signal non-uniformities of camera's photosensor.

  2. Accurate Monitoring and Fault Detection in Wind Measuring Devices through Wireless Sensor Networks

    PubMed Central

    Khan, Komal Saifullah; Tariq, Muhammad

    2014-01-01

    Many wind energy projects report poor performance as low as 60% of the predicted performance. The reason for this is poor resource assessment and the use of new untested technologies and systems in remote locations. Predictions about the potential of an area for wind energy projects (through simulated models) may vary from the actual potential of the area. Hence, introducing accurate site assessment techniques will lead to accurate predictions of energy production from a particular area. We solve this problem by installing a Wireless Sensor Network (WSN) to periodically analyze the data from anemometers installed in that area. After comparative analysis of the acquired data, the anemometers transmit their readings through a WSN to the sink node for analysis. The sink node uses an iterative algorithm which sequentially detects any faulty anemometer and passes the details of the fault to the central system or main station. We apply the proposed technique in simulation as well as in practical implementation and study its accuracy by comparing the simulation results with experimental results to analyze the variation in the results obtained from both simulation model and implemented model. Simulation results show that the algorithm indicates faulty anemometers with high accuracy and low false alarm rate when as many as 25% of the anemometers become faulty. Experimental analysis shows that anemometers incorporating this solution are better assessed and performance level of implemented projects is increased above 86% of the simulated models. PMID:25421739

  3. Accurate monitoring and fault detection in wind measuring devices through wireless sensor networks.

    PubMed

    Khan, Komal Saifullah; Tariq, Muhammad

    2014-11-24

    Many wind energy projects report poor performance as low as 60% of the predicted performance. The reason for this is poor resource assessment and the use of new untested technologies and systems in remote locations. Predictions about the potential of an area for wind energy projects (through simulated models) may vary from the actual potential of the area. Hence, introducing accurate site assessment techniques will lead to accurate predictions of energy production from a particular area. We solve this problem by installing a Wireless Sensor Network (WSN) to periodically analyze the data from anemometers installed in that area. After comparative analysis of the acquired data, the anemometers transmit their readings through a WSN to the sink node for analysis. The sink node uses an iterative algorithm which sequentially detects any faulty anemometer and passes the details of the fault to the central system or main station. We apply the proposed technique in simulation as well as in practical implementation and study its accuracy by comparing the simulation results with experimental results to analyze the variation in the results obtained from both simulation model and implemented model. Simulation results show that the algorithm indicates faulty anemometers with high accuracy and low false alarm rate when as many as 25% of the anemometers become faulty. Experimental analysis shows that anemometers incorporating this solution are better assessed and performance level of implemented projects is increased above 86% of the simulated models.

  4. No Galaxy Left Behind: Accurate Measurements with the Faintest Objects in the Dark Energy Survey

    SciTech Connect

    Suchyta, E.

    2016-01-27

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of stars or galaxies detectable in an imaging survey. We have implemented our proposal in Balrog, a software package which embeds fake objects in real imaging in order to accurately characterize measurement biases. We also demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a wide variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the standard LandySzalay correlation function estimator suppresses the effects of variable survey selection by at least two orders of magnitude. Now our measured angular clustering is found to be in excellent agreement with that of a matched sample drawn from much deeper, higherresolution space-based COSMOS imaging; over angular scales of 0.004° < θ < 0.2 ° , we find a best-fit scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending the statistical reach of measurements in a wide variety of coming imaging surveys.

  5. No galaxy left behind: accurate measurements with the faintest objects in the Dark Energy Survey

    NASA Astrophysics Data System (ADS)

    Suchyta, E.; Huff, E. M.; Aleksić, J.; Melchior, P.; Jouvel, S.; MacCrann, N.; Ross, A. J.; Crocce, M.; Gaztanaga, E.; Honscheid, K.; Leistedt, B.; Peiris, H. V.; Rykoff, E. S.; Sheldon, E.; Abbott, T.; Abdalla, F. B.; Allam, S.; Banerji, M.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; James, D. J.; Jarvis, M.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Miller, C. J.; Miquel, R.; Neilsen, E.; Nichol, R. C.; Nord, B.; Ogando, R.; Percival, W. J.; Reil, K.; Roodman, A.; Sako, M.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, D.; Vikram, V.; Walker, A. R.; Wechsler, R. H.; Zhang, Y.; DES Collaboration

    2016-03-01

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of detectable stars or galaxies. We have implemented our proposal in BALROG, software which embeds fake objects in real imaging to accurately characterize measurement biases. We demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the Landy-Szalay estimator suppresses the effects of variable survey selection by at least two orders of magnitude. With this correction, our measured angular clustering is found to be in excellent agreement with that of a matched sample from much deeper, higher resolution space-based Cosmological Evolution Survey (COSMOS) imaging; over angular scales of 0.004° < θ < 0.2°, we find a best-fitting scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending measurements' statistical reach in a variety of upcoming imaging surveys.

  6. No Galaxy Left Behind: Accurate Measurements with the Faintest Objects in the Dark Energy Survey

    DOE PAGES

    Suchyta, E.

    2016-01-27

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of stars or galaxies detectable in an imaging survey. We have implemented our proposal in Balrog, a software package which embeds fake objects in real imaging in order to accurately characterize measurement biases.more » We also demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a wide variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the standard LandySzalay correlation function estimator suppresses the effects of variable survey selection by at least two orders of magnitude. Now our measured angular clustering is found to be in excellent agreement with that of a matched sample drawn from much deeper, higherresolution space-based COSMOS imaging; over angular scales of 0.004° < θ < 0.2 ° , we find a best-fit scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending the statistical reach of measurements in a wide variety of coming imaging surveys.« less

  7. A fast and accurate image-based measuring system for isotropic reflection materials

    NASA Astrophysics Data System (ADS)

    Kim, Duck Bong; Kim, Kang Yeon; Park, Kang Su; Seo, Myoung Kook; Lee, Kwan H.

    2008-08-01

    We present a novel image-based BRDF (Bidirectional Reflectance Distribution Function) measurement system for materials that have isotropic reflectance properties. Our proposed system is fast due to simple set up and automated operations. It also provides a wide angular coverage and noise reduction capability so that it achieves accuracy that is needed for computer graphics applications. We test the uniformity and constancy of the light source and the reciprocity of the measurement system. We perform a photometric calibration of HDR (High Dynamic Range) camera to recover an accurate radiance map from each HDR image. We verify our proposed system by comparing it with a previous imagebased BRDF measurement system. We demonstrate the efficiency and accuracy of our proposed system by generating photorealistic images of the measured BRDF data that include glossy blue, green plastics, gold coated metal and gold metallic paints.

  8. Accurate Alternative Measurements for Female Lifetime Reproductive Success in Drosophila melanogaster

    PubMed Central

    Nguyen, Trinh T. X.; Moehring, Amanda J.

    2015-01-01

    Fitness is an individual’s ability to survive and reproduce, and is an important concept in evolutionary biology. However, accurately measuring fitness is often difficult, and appropriate fitness surrogates need to be identified. Lifetime reproductive success, the total progeny an organism can produce in their lifetime, is thought to be a suitable proxy for fitness, but the measure of an organism’s reproductive output across a lifetime can be difficult or impossible to obtain. Here we demonstrate that the short-term measure of reproductive success across five days provides a reasonable prediction of an individual's total lifetime reproductive success in Drosophila melanogaster. However, the lifetime reproductive success of a female that has only mated once is not correlated to the lifetime reproductive success of a female that is allowed to mate multiple times, demonstrating that these measures should not serve as surrogates nor be used to make inferences about one another. PMID:26125633

  9. Combining MFD and PIE for accurate single-pair Förster resonance energy transfer measurements.

    PubMed

    Kudryavtsev, Volodymyr; Sikor, Martin; Kalinin, Stanislav; Mokranjac, Dejana; Seidel, Claus A M; Lamb, Don C

    2012-03-01

    Single-pair Förster resonance energy transfer (spFRET) experiments using single-molecule burst analysis on a confocal microscope are an ideal tool to measure inter- and intramolecular distances and dynamics on the nanoscale. Different techniques have been developed to maximize the amount of information available in spFRET burst analysis experiments. Multiparameter fluorescence detection (MFD) is used to monitor a variety of fluorescence parameters simultaneously and pulsed interleaved excitation (PIE) employs direct excitation of the acceptor to probe its presence and photoactivity. To calculate accurate FRET efficiencies from spFRET experiments with MFD or PIE, several calibration measurements are usually required. Herein, we demonstrate that by combining MFD with PIE information regarding all calibration factors as well as an accurate determination of spFRET histograms can be performed in a single measurement. In addition, the quality of overlap of the different detection volumes as well as the detection of acceptor photophysics can be investigated with MFD-PIE. Bursts containing acceptor photobleaching can be identified and excluded from further investigation while bursts that contain FRET dynamics are unaffected by this analysis. We have employed MFD-PIE to accurately analyze the effects of nucleotides and substrate on the interdomain separation in DnaK, the major bacterial heat shock protein 70 (Hsp70). The interdomain distance increases from 47 Å in the ATP-bound state to 84 Å in the ADP-bound state and slightly contracts to 77 Å when a substrate is bound. This is in contrast to what was observed for the mitochondrial member of the Hsp70s, Ssc1, supporting the notion of evolutionary specialization of Hsp70s for different cellular functions in different organisms and cell organelles.

  10. Accurate Measurements of Aerosol Hygroscopic Growth over a Wide Range in Relative Humidity.

    PubMed

    Rovelli, Grazia; Miles, Rachael E H; Reid, Jonathan P; Clegg, Simon L

    2016-06-30

    Using a comparative evaporation kinetics approach, we describe a new and accurate method for determining the equilibrium hygroscopic growth of aerosol droplets. The time-evolving size of an aqueous droplet, as it evaporates to a steady size and composition that is in equilibrium with the gas phase relative humidity, is used to determine the time-dependent mass flux of water, yielding information on the vapor pressure of water above the droplet surface at every instant in time. Accurate characterization of the gas phase relative humidity is provided from a control measurement of the evaporation profile of a droplet of know equilibrium properties, either a pure water droplet or a sodium chloride droplet. In combination, and by comparison with simulations that account for both the heat and mass transport governing the droplet evaporation kinetics, these measurements allow accurate retrieval of the equilibrium properties of the solution droplet (i.e., the variations with water activity in the mass fraction of solute, diameter growth factor, osmotic coefficient or number of water molecules per solute molecule). Hygroscopicity measurements can be made over a wide range in water activity (from >0.99 to, in principle, <0.05) on time scales of <10 s for droplets containing involatile or volatile solutes. The approach is benchmarked for binary and ternary inorganic solution aerosols with typical uncertainties in water activity of <±0.2% at water activities >0.9 and ∼±1% below 80% RH, and maximum uncertainties in diameter growth factor of ±0.7%. For all of the inorganic systems examined, the time-dependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1).

  11. Note: long range and accurate measurement of deep trench microstructures by a specialized scanning tunneling microscope.

    PubMed

    Ju, Bing-Feng; Chen, Yuan-Liu; Zhang, Wei; Zhu, Wule; Jin, Chao; Fang, F Z

    2012-05-01

    A compact but practical scanning tunneling microscope (STM) with high aspect ratio and high depth capability has been specially developed. Long range scanning mechanism with tilt-adjustment stage is adopted for the purpose of adjusting the probe-sample relative angle to compensate the non-parallel effects. A periodical trench microstructure with a pitch of 10 μm has been successfully imaged with a long scanning range up to 2.0 mm. More innovatively, a deep trench with depth and step height of 23.0 μm has also been successfully measured, and slope angle of the sidewall can approximately achieve 67°. The probe can continuously climb the high step and exploring the trench bottom without tip crashing. The new STM could perform long range measurement for the deep trench and high step surfaces without image distortion. It enables accurate measurement and quality control of periodical trench microstructures.

  12. Easy Leaf Area: Automated digital image analysis for rapid and accurate measurement of leaf area1

    PubMed Central

    Easlon, Hsien Ming; Bloom, Arnold J.

    2014-01-01

    • Premise of the study: Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. • Methods and Results: Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. • Conclusions: Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images. PMID:25202639

  13. Fiddler crabs accurately measure two-dimensional distance over three-dimensional terrain.

    PubMed

    Walls, Michael L; Layne, John E

    2009-10-01

    Foraging fiddler crabs (Uca spp.) monitor the location of, and are able to return to, their burrows by employing path integration. This requires them to accurately measure both the directions and distances of their locomotory movements. Even though most fiddler crabs inhabit relatively flat terrain, they must cope with vertical features of their environment, such as sloping beaches, mounds and shells, which may represent significant obstacles. To determine whether fiddler crabs can successfully perform path integration among such three-dimensional obstacles, we tested their ability to measure distance while we imposed a vertical detour. By inserting a large hill in the homeward path of foraging crabs we show that fiddler crabs can cope with vertical detours: they accurately travel the correct horizontal distance, despite the fact that the shape of the hill forces them to change their gait from what would be used on flat ground. Our results demonstrate a flexible path integrator capable of measuring, and either integrating or discarding, the vertical dimension.

  14. Accurate Measurements of Aircraft Engine Soot Emissions Using a CAPS PMssa Monitor

    NASA Astrophysics Data System (ADS)

    Onasch, Timothy; Thompson, Kevin; Renbaum-Wolff, Lindsay; Smallwood, Greg; Make-Lye, Richard; Freedman, Andrew

    2016-04-01

    We present results of aircraft engine soot emissions measurements during the VARIAnT2 campaign using CAPS PMssa monitors. VARIAnT2, an aircraft engine non-volatile particulate matter (nvPM) emissions field campaign, was focused on understanding the variability in nvPM mass measurements using different measurement techniques and accounting for possible nvPM sampling system losses. The CAPS PMssa monitor accurately measures both the optical extinction and scattering (and thus single scattering albedo and absorption) of an extracted sample using the same sample volume for both measurements with a time resolution of 1 second and sensitivity of better than 1 Mm-1. Absorption is obtained by subtracting the scattering signal from the total extinction. Given that the single scattering albedo of the particulates emitted from the aircraft engine measured at both 630 and 660 nm was on the order of 0.1, any inaccuracy in the scattering measurement has little impact on the accuracy of the ddetermined absorption coefficient. The absorption is converted into nvPM mass using a documented Mass Absorption Coefficient (MAC). Results of soot emission indices (mass soot emitted per mass of fuel consumed) for a turbojet engine as a function of engine power will be presented and compared to results obtained using an EC/OC monitor.

  15. Accurate Measurements of the Dielectric Constant of Seawater at L Band

    NASA Technical Reports Server (NTRS)

    Lang, Roger; Zhou, Yiwen; Utku, Cuneyt; Le Vine, David

    2016-01-01

    This paper describes measurements of the dielectric constant of seawater at a frequency of 1.413 GHz, the center of the protected band (i.e., passive use only) used in the measurement of sea surface salinity from space. The objective of the measurements is to accurately determine the complex dielectric constant of seawater as a function of salinity and temperature. A resonant cylindrical microwave cavity in transmission mode has been employed to make the measurements. The measurements are made using standard seawater at salinities of 30, 33, 35, and 38 practical salinity units over a range of temperatures from 0 degree C to 35 degree C in 5 degree C intervals. Repeated measurements have been made at each temperature and salinity. Mean values and standard deviations are then computed. The total error budget indicates that the real and imaginary parts of the dielectric constant have a combined standard uncertainty of about 0.3 over the range of salinities and temperatures considered. The measurements are compared with the dielectric constants obtained from the model functions of Klein and Swift and those of Meissner and Wentz. The biggest differences occur at low and high temperatures.

  16. Ocean Lidar Measurements of Beam Attenuation and a Roadmap to Accurate Phytoplankton Biomass Estimates

    NASA Astrophysics Data System (ADS)

    Hu, Yongxiang; Behrenfeld, Mike; Hostetler, Chris; Pelon, Jacques; Trepte, Charles; Hair, John; Slade, Wayne; Cetinic, Ivona; Vaughan, Mark; Lu, Xiaomei; Zhai, Pengwang; Weimer, Carl; Winker, David; Verhappen, Carolus C.; Butler, Carolyn; Liu, Zhaoyan; Hunt, Bill; Omar, Ali; Rodier, Sharon; Lifermann, Anne; Josset, Damien; Hou, Weilin; MacDonnell, David; Rhew, Ray

    2016-06-01

    Beam attenuation coefficient, c, provides an important optical index of plankton standing stocks, such as phytoplankton biomass and total particulate carbon concentration. Unfortunately, c has proven difficult to quantify through remote sensing. Here, we introduce an innovative approach for estimating c using lidar depolarization measurements and diffuse attenuation coefficients from ocean color products or lidar measurements of Brillouin scattering. The new approach is based on a theoretical formula established from Monte Carlo simulations that links the depolarization ratio of sea water to the ratio of diffuse attenuation Kd and beam attenuation C (i.e., a multiple scattering factor). On July 17, 2014, the CALIPSO satellite was tilted 30° off-nadir for one nighttime orbit in order to minimize ocean surface backscatter and demonstrate the lidar ocean subsurface measurement concept from space. Depolarization ratios of ocean subsurface backscatter are measured accurately. Beam attenuation coefficients computed from the depolarization ratio measurements compare well with empirical estimates from ocean color measurements. We further verify the beam attenuation coefficient retrievals using aircraft-based high spectral resolution lidar (HSRL) data that are collocated with in-water optical measurements.

  17. Optimally accurate thermal-wave cavity photopyroelectric measurements of pressure-dependent thermophysical properties of air: theory and experiments.

    PubMed

    Kwan, Chi-Hang; Matvienko, Anna; Mandelis, Andreas

    2007-10-01

    An experimental technique for the measurement of thermal properties of air at low pressures using a photopyroelectric (PPE) thermal-wave cavity (TWC) was developed. In addition, two theoretical approaches, a conventional one-dimensional thermal-wave model and a three-dimensional theory based on the Hankel integral, were applied to interpret the thermal-wave field in the thermal-wave cavity. The importance of radiation heat transfer mechanisms in a TWC was also investigated. Radiation components were added to the purely conductive model by linearizing the radiation heat transfer component at the cavity boundary. The experimental results indicate that the three-dimensional model is necessary to describe the PPE signal, especially at low frequencies where thermal diffusion length is large and sideways propagation of the thermal-wave field becomes significant. Radiation is found to be the dominant contributor of the PPE signal at high frequencies and large cavity lengths, where heat conduction across the TWC length is relatively weak. The three-dimensional theory and the Downhill Simplex algorithm were used to fit the experimental data and extract the thermal diffusivity of air and the heat transfer coefficient in a wide range of pressures from 760 to 2.6 Torr. It was shown that judicious adjustments of cavity length and computational best fits to frequency-scanned data using three-dimensional photopyroelectric theory lead to optimally accurate value measurements of thermal diffusivity and heat transfer coefficient at various pressures.

  18. Experimental comparison of exchange bias measurement methodologies

    SciTech Connect

    Hovorka, Ondrej; Berger, Andreas; Friedman, Gary

    2007-05-01

    Measurements performed on all-ferromagnetic bilayer systems and supported by model calculation results are used to compare different exchange bias characterization methods. We demonstrate that the accuracy of the conventional two-point technique based on measuring the sum of the coercive fields depends on the symmetry properties of hysteresis loops. On the other hand, the recently proposed center of mass method yields results independent of the hysteresis loop type and coincides with the two-point measurement only if the loops are symmetric. Our experimental and simulation results clearly demonstrate a strong correlation between loop asymmetry and the difference between these methods.

  19. Accurate Measurements of the Dielectric Constant of Seawater at L Band

    NASA Technical Reports Server (NTRS)

    Lang, Roger H.; Utku, Cuneyt; Tarkocin, Yalcin; LeVine, David M.

    2010-01-01

    This report describes measurements of the dielectric constant of seawater at a frequency of 1.413 GHz that is at the center of the L-Sand radiometric protected frequency spectrum. Aquarius will be sensing the sea surface salinity from space in this band. The objective of the project is to refine the model function for the dielectric constant as a function of salinity and temperature so that remote sensing measurements can be made with the accuracy needed to meet the measurement goals (0.2 psu) of the Aquarius mission. The measurements were made, using a microwave cavity operated in the transmission configuration. The cavity's temperature was accurately regulated to 0.02 C by immersing it in a temperature controlled bath of distilled water and ethanol glycol. Seawater had been purchased from Ocean Scientific International Limited (OS1L) at salinities of 30, 35 and 38 psu. Measurements of these seawater samples were then made over a range of temperatures, from l0 C to 35 C in 5 C intervals. Repeated measurements were made at each temperature and salinity, Mean values and standard deviations were then computed. Total error budgets indicated that the real and imaginary parts of the dielectric constant had a relative accuracy of about l%.

  20. Accurate Measurement of the in vivo Ammonium Concentration in Saccharomyces cerevisiae.

    PubMed

    Cueto-Rojas, Hugo F; Maleki Seifar, Reza; Ten Pierick, Angela; Heijnen, Sef J; Wahl, Aljoscha

    2016-04-23

    Ammonium (NH₄⁺) is the most common N-source for yeast fermentations, and N-limitation is frequently applied to reduce growth and increase product yields. While there is significant molecular knowledge on NH₄⁺ transport and assimilation, there have been few attempts to measure the in vivo concentration of this metabolite. In this article, we present a sensitive and accurate analytical method to quantify the in vivo intracellular ammonium concentration in Saccharomyces cerevisiae based on standard rapid sampling and metabolomics techniques. The method validation experiments required the development of a proper sample processing protocol to minimize ammonium production/consumption during biomass extraction by assessing the impact of amino acid degradation-an element that is often overlooked. The resulting cold chloroform metabolite extraction method, together with quantification using ultra high performance liquid chromatography-isotope dilution mass spectrometry (UHPLC-IDMS), was not only more sensitive than most of the existing methods but also more accurate than methods that use electrodes, enzymatic reactions, or boiling water or boiling ethanol biomass extraction because it minimized ammonium consumption/production during sampling processing and interference from other metabolites in the quantification of intracellular ammonium. Finally, our validation experiments showed that other metabolites such as pyruvate or 2-oxoglutarate (αKG) need to be extracted with cold chloroform to avoid measurements being biased by the degradation of other metabolites (e.g., amino acids).

  1. Accurate size measurement of monosize calibration spheres by differential mobility analysis

    SciTech Connect

    Mulholland, George W.; Fernandez, Marco

    1998-11-24

    A differential mobility analyzer was used to measure the mean particle size of three monosize suspensions of polystyrene spheres in water. Key features of the experiment to minimize the uncertainty in the results include developing a recirculating flow to ensure equal flows into and out of the classifier, an accurate divider circuit for calibrating the electrode voltage, and use of the 100.7 nm NIST SRM for calibrating the flow of the classifier. The measured average sizes and expanded uncertainties with a coverage factor of 2 are 92.4 nm{+-}1.1 nm, 126.9 nm{+-}1.4 nm, and 217.7 nm{+-}3.4 nm. These calibration sizes were characterized by NIST to improve the calibration of scanning surface inspection systems.

  2. An Inexpensive, Stable, and Accurate Relative Humidity Measurement Method for Challenging Environments.

    PubMed

    Zhang, Wei; Ma, Hong; Yang, Simon X

    2016-03-18

    In this research, an improved psychrometer is developed to solve practical issues arising in the relative humidity measurement of challenging drying environments for meat manufacturing in agricultural and agri-food industries. The design in this research focused on the structure of the improved psychrometer, signal conversion, and calculation methods. The experimental results showed the effect of varying psychrometer structure on relative humidity measurement accuracy. An industrial application to dry-cured meat products demonstrated the effective performance of the improved psychrometer being used as a relative humidity measurement sensor in meat-drying rooms. In a drying environment for meat manufacturing, the achieved measurement accuracy for relative humidity using the improved psychrometer was ±0.6%. The system test results showed that the improved psychrometer can provide reliable and long-term stable relative humidity measurements with high accuracy in the drying system of meat products.

  3. An Inexpensive, Stable, and Accurate Relative Humidity Measurement Method for Challenging Environments

    PubMed Central

    Zhang, Wei; Ma, Hong; Yang, Simon X.

    2016-01-01

    In this research, an improved psychrometer is developed to solve practical issues arising in the relative humidity measurement of challenging drying environments for meat manufacturing in agricultural and agri-food industries. The design in this research focused on the structure of the improved psychrometer, signal conversion, and calculation methods. The experimental results showed the effect of varying psychrometer structure on relative humidity measurement accuracy. An industrial application to dry-cured meat products demonstrated the effective performance of the improved psychrometer being used as a relative humidity measurement sensor in meat-drying rooms. In a drying environment for meat manufacturing, the achieved measurement accuracy for relative humidity using the improved psychrometer was ±0.6%. The system test results showed that the improved psychrometer can provide reliable and long-term stable relative humidity measurements with high accuracy in the drying system of meat products. PMID:26999161

  4. A solution for measuring accurate reaction time to visual stimuli realized with a programmable microcontroller.

    PubMed

    Ohyanagi, Toshio; Sengoku, Yasuhito

    2010-02-01

    This article presents a new solution for measuring accurate reaction time (SMART) to visual stimuli. The SMART is a USB device realized with a Cypress Programmable System-on-Chip (PSoC) mixed-signal array programmable microcontroller. A brief overview of the hardware and firmware of the PSoC is provided, together with the results of three experiments. In Experiment 1, we investigated the timing accuracy of the SMART in measuring reaction time (RT) under different conditions of operating systems (OSs; Windows XP or Vista) and monitor displays (a CRT or an LCD). The results indicated that the timing error in measuring RT by the SMART was less than 2 msec, on average, under all combinations of OS and display and that the SMART was tolerant to jitter and noise. In Experiment 2, we tested the SMART with 8 participants. The results indicated that there was no significant difference among RTs obtained with the SMART under the different conditions of OS and display. In Experiment 3, we used Microsoft (MS) PowerPoint to present visual stimuli on the display. We found no significant difference in RTs obtained using MS DirectX technology versus using the PowerPoint file with the SMART. We are certain that the SMART is a simple and practical solution for measuring RTs accurately. Although there are some restrictions in using the SMART with RT paradigms, the SMART is capable of providing both researchers and health professionals working in clinical settings with new ways of using RT paradigms in their work.

  5. The use of experimental bending tests to more accurate numerical description of TBC damage process

    NASA Astrophysics Data System (ADS)

    Sadowski, T.; Golewski, P.

    2016-04-01

    Thermal barrier coatings (TBCs) have been extensively used in aircraft engines to protect critical engine parts such as blades and combustion chambers, which are exposed to high temperatures and corrosive environment. The blades of turbine engines are additionally exposed to high mechanical loads. These loads are created by the high rotational speed of the rotor (30 000 rot/min), causing the tensile and bending stresses. Therefore, experimental testing of coated samples is necessary in order to determine strength properties of TBCs. Beam samples with dimensions 50×10×2 mm were used in those studies. The TBC system consisted of 150 μm thick bond coat (NiCoCrAlY) and 300 μm thick top coat (YSZ) made by APS (air plasma spray) process. Samples were tested by three-point bending test with various loads. After bending tests, the samples were subjected to microscopic observation to determine the quantity of cracks and their depth. The above mentioned results were used to build numerical model and calibrate material data in Abaqus program. Brittle cracking damage model was applied for the TBC layer, which allows to remove elements after reaching criterion. Surface based cohesive behavior was used to model the delamination which may occur at the boundary between bond coat and top coat.

  6. Home Circadian Phase Assessments with Measures of Compliance Yield Accurate Dim Light Melatonin Onsets

    PubMed Central

    Burgess, Helen J.; Wyatt, James K.; Park, Margaret; Fogg, Louis F.

    2015-01-01

    Study Objectives: There is a need for the accurate assessment of circadian phase outside of the clinic/laboratory, particularly with the gold standard dim light melatonin onset (DLMO). We tested a novel kit designed to assist in saliva sampling at home for later determination of the DLMO. The home kit includes objective measures of compliance to the requirements for dim light and half-hourly saliva sampling. Design: Participants were randomized to one of two 10-day protocols. Each protocol consisted of two back-to-back home and laboratory phase assessments in counterbalanced order, separated by a 5-day break. Setting: Laboratory or participants' homes. Participants: Thirty-five healthy adults, age 21–62 y. Interventions: N/A. Measurements and Results: Most participants received at least one 30-sec epoch of light > 50 lux during the home phase assessments (average light intensity 4.5 lux), but on average for < 9 min of the required 8.5 h. Most participants collected every saliva sample within 5 min of the scheduled time. Ninety-two percent of home DLMOs were not affected by light > 50 lux or sampling errors. There was no significant difference between the home and laboratory DLMOs (P > 0.05); on average the home DLMOs occurred 9.6 min before the laboratory DLMOs. The home DLMOs were highly correlated with the laboratory DLMOs (r = 0.91, P < 0.001). Conclusions: Participants were reasonably compliant to the home phase assessment procedures. The good agreement between the home and laboratory dim light melatonin onsets (DLMOs) demonstrates that including objective measures of light exposure and sample timing during home saliva sampling can lead to accurate home DLMOs. Clinical Trial Registration: Circadian Phase Assessments at Home, http://clinicaltrials.gov/show/NCT01487252, NCT01487252. Citation: Burgess HJ, Wyatt JK, Park M, Fogg LF. Home circadian phase assessments with measures of compliance yield accurate dim light melatonin onsets. SLEEP 2015;38(6):889–897

  7. k-Space Image Correlation Spectroscopy: A Method for Accurate Transport Measurements Independent of Fluorophore Photophysics

    PubMed Central

    Kolin, David L.; Ronis, David; Wiseman, Paul W.

    2006-01-01

    We present the theory and application of reciprocal space image correlation spectroscopy (kICS). This technique measures the number density, diffusion coefficient, and velocity of fluorescently labeled macromolecules in a cell membrane imaged on a confocal, two-photon, or total internal reflection fluorescence microscope. In contrast to r-space correlation techniques, we show kICS can recover accurate dynamics even in the presence of complex fluorophore photobleaching and/or “blinking”. Furthermore, these quantities can be calculated without nonlinear curve fitting, or any knowledge of the beam radius of the exciting laser. The number densities calculated by kICS are less sensitive to spatial inhomogeneity of the fluorophore distribution than densities measured using image correlation spectroscopy. We use simulations as a proof-of-principle to show that number densities and transport coefficients can be extracted using this technique. We present calibration measurements with fluorescent microspheres imaged on a confocal microscope, which recover Stokes-Einstein diffusion coefficients, and flow velocities that agree with single particle tracking measurements. We also show the application of kICS to measurements of the transport dynamics of α5-integrin/enhanced green fluorescent protein constructs in a transfected CHO cell imaged on a total internal reflection fluorescence microscope using charge-coupled device area detection. PMID:16861272

  8. How accurately will SWOT measurements be able to characterize river discharge?

    NASA Astrophysics Data System (ADS)

    Durand, M.; Alsdorf, D.; Bates, P.; Rodríguez, E.; Andreadis, K.; Clark, E.

    2008-12-01

    The Surface Water and Ocean Topography (SWOT) mission is a swath mapping radar altimeter that would provide new measurements of inland water surface elevation (WSE) for rivers, lakes, wetlands and reservoirs. SWOT has been recommended by the National Research Council Decadal Survey to measure ocean topography as well as WSE over land; the proposed launch date timeframe is between 2013 - 2016. SWOT WSE estimates would provide a source of information for characterizing streamflow globally. In this paper, we evaluate the accuracy of river discharge estimates obtained from SWOT measurements over the Ohio River and eight of its major tributaries within the context of a virtual mission (VM). SWOT VM measurements are obtained by simulation from the hydrodynamic model LISFLOOD, using USGS streamflow gages as boundary conditions and validation data. SWOT measurements are then input into an algorithm to obtain estimates of discharge variations. The algorithm is based on Manning's equation, in which river width and slope are obtained from SWOT, roughness is estimated a priori. Three different algorithms are used to estimate depth. SWOT discharge estimates are compared to the discharge simulated by LISFLOOD. In this way, we are able to characterize the accuracy of SWOT estimates of instantaneous discharge. More specifically, we characterize how SWOT accuracy varies as a function of the river characteristics and contributing area, such as Strahler order. More accurate depth and discharge estimates can be obtained by data assimilation, but will be more computationally expensive.

  9. Three-Signal Method for Accurate Measurements of Depolarization Ratio with Lidar

    NASA Technical Reports Server (NTRS)

    Reichardt, Jens; Baumgart, Rudolf; McGee, Thomsa J.

    2003-01-01

    A method is presented that permits the determination of atmospheric depolarization-ratio profiles from three elastic-backscatter lidar signals with different sensitivity to the state of polarization of the backscattered light. The three-signal method is insensitive to experimental errors and does not require calibration of the measurement, which could cause large systematic uncertainties of the results, as is the case in the lidar technique conventionally used for the observation of depolarization ratios.

  10. Accurate and automatic extrinsic calibration method for blade measurement system integrated by different optical sensors

    NASA Astrophysics Data System (ADS)

    He, Wantao; Li, Zhongwei; Zhong, Kai; Shi, Yusheng; Zhao, Can; Cheng, Xu

    2014-11-01

    Fast and precise 3D inspection system is in great demand in modern manufacturing processes. At present, the available sensors have their own pros and cons, and hardly exist an omnipotent sensor to handle the complex inspection task in an accurate and effective way. The prevailing solution is integrating multiple sensors and taking advantages of their strengths. For obtaining a holistic 3D profile, the data from different sensors should be registrated into a coherent coordinate system. However, some complex shape objects own thin wall feather such as blades, the ICP registration method would become unstable. Therefore, it is very important to calibrate the extrinsic parameters of each sensor in the integrated measurement system. This paper proposed an accurate and automatic extrinsic parameter calibration method for blade measurement system integrated by different optical sensors. In this system, fringe projection sensor (FPS) and conoscopic holography sensor (CHS) is integrated into a multi-axis motion platform, and the sensors can be optimally move to any desired position at the object's surface. In order to simple the calibration process, a special calibration artifact is designed according to the characteristics of the two sensors. An automatic registration procedure based on correlation and segmentation is used to realize the artifact datasets obtaining by FPS and CHS rough alignment without any manual operation and data pro-processing, and then the Generalized Gauss-Markoff model is used to estimate the optimization transformation parameters. The experiments show the measurement result of a blade, where several sampled patches are merged into one point cloud, and it verifies the performance of the proposed method.

  11. Accurate label-free reaction kinetics determination using initial rate heat measurements

    PubMed Central

    Ebrahimi, Kourosh Honarmand; Hagedoorn, Peter-Leon; Jacobs, Denise; Hagen, Wilfred R.

    2015-01-01

    Accurate label-free methods or assays to obtain the initial reaction rates have significant importance in fundamental studies of enzymes and in application-oriented high throughput screening of enzyme activity. Here we introduce a label-free approach for obtaining initial rates of enzyme activity from heat measurements, which we name initial rate calorimetry (IrCal). This approach is based on our new finding that the data recorded by isothermal titration calorimetry for the early stages of a reaction, which have been widely ignored, are correlated to the initial rates. Application of the IrCal approach to various enzymes led to accurate enzyme kinetics parameters as compared to spectroscopic methods and enabled enzyme kinetic studies with natural substrate, e.g. proteases with protein substrates. Because heat is a label-free property of almost all reactions, the IrCal approach holds promise in fundamental studies of various enzymes and in use of calorimetry for high throughput screening of enzyme activity. PMID:26574737

  12. Accurate in situ measurement of complex refractive index and particle size in intralipid emulsions.

    PubMed

    Dong, Miao L; Goyal, Kashika G; Worth, Bradley W; Makkar, Sorab S; Calhoun, William R; Bali, Lalit M; Bali, Samir

    2013-08-01

    A first accurate measurement of the complex refractive index in an intralipid emulsion is demonstrated, and thereby the average scatterer particle size using standard Mie scattering calculations is extracted. Our method is based on measurement and modeling of the reflectance of a divergent laser beam from the sample surface. In the absence of any definitive reference data for the complex refractive index or particle size in highly turbid intralipid emulsions, we base our claim of accuracy on the fact that our work offers several critically important advantages over previously reported attempts. First, our measurements are in situ in the sense that they do not require any sample dilution, thus eliminating dilution errors. Second, our theoretical model does not employ any fitting parameters other than the two quantities we seek to determine, i.e., the real and imaginary parts of the refractive index, thus eliminating ambiguities arising from multiple extraneous fitting parameters. Third, we fit the entire reflectance-versus-incident-angle data curve instead of focusing on only the critical angle region, which is just a small subset of the data. Finally, despite our use of highly scattering opaque samples, our experiment uniquely satisfies a key assumption behind the Mie scattering formalism, namely, no multiple scattering occurs. Further proof of our method's validity is given by the fact that our measured particle size finds good agreement with the value obtained by dynamic light scattering.

  13. Accurate in situ measurement of complex refractive index and particle size in intralipid emulsions

    NASA Astrophysics Data System (ADS)

    Dong, Miao L.; Goyal, Kashika G.; Worth, Bradley W.; Makkar, Sorab S.; Calhoun, William R.; Bali, Lalit M.; Bali, Samir

    2013-08-01

    A first accurate measurement of the complex refractive index in an intralipid emulsion is demonstrated, and thereby the average scatterer particle size using standard Mie scattering calculations is extracted. Our method is based on measurement and modeling of the reflectance of a divergent laser beam from the sample surface. In the absence of any definitive reference data for the complex refractive index or particle size in highly turbid intralipid emulsions, we base our claim of accuracy on the fact that our work offers several critically important advantages over previously reported attempts. First, our measurements are in situ in the sense that they do not require any sample dilution, thus eliminating dilution errors. Second, our theoretical model does not employ any fitting parameters other than the two quantities we seek to determine, i.e., the real and imaginary parts of the refractive index, thus eliminating ambiguities arising from multiple extraneous fitting parameters. Third, we fit the entire reflectance-versus-incident-angle data curve instead of focusing on only the critical angle region, which is just a small subset of the data. Finally, despite our use of highly scattering opaque samples, our experiment uniquely satisfies a key assumption behind the Mie scattering formalism, namely, no multiple scattering occurs. Further proof of our method's validity is given by the fact that our measured particle size finds good agreement with the value obtained by dynamic light scattering.

  14. Accurate Measurement of Velocity and Acceleration of Seismic Vibrations near Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Arif, Syed Javed; Imdadullah; Asghar, Mohammad Syed Jamil

    In spite of all prerequisite geological study based precautions, the sites of nuclear power plants are also susceptible to seismic vibrations and their consequent effects. The effect of the ongoing nuclear tragedy in Japan caused by an earthquake and its consequent tsunami on March 11, 2011 is currently beyond contemplations. It has led to a rethinking on nuclear power stations by various governments around the world. Therefore, the prediction of location and time of large earthquakes has regained a great importance. The earth crust is made up of several wide, thin and rigid plates like blocks which are in constant motion with respect to each other. A series of vibrations on the earth surface are produced by the generation of elastic seismic waves due to sudden rupture within the plates during the release of accumulated strain energy. The range of frequency of seismic vibrations is from 0 to 10 Hz. However, there appears a large variation in magnitude, velocity and acceleration of these vibrations. The response of existing or conventional methods of measurement of seismic vibrations is very slow, which is of the order of tens of seconds. A systematic and high resolution measurement of velocity and acceleration of these vibrations are useful to interpret the pattern of waves and their anomalies more accurately, which are useful for the prediction of an earthquake. In the proposed work, a fast rotating magnetic field (RMF) is used to measure the velocity and acceleration of seismic vibrations in the millisecond range. The broad spectrum of pulses within one second range, measured by proposed method, gives all possible values of instantaneous velocity and instantaneous acceleration of the seismic vibrations. The spectrum of pulses in millisecond range becomes available which is useful to measure the pattern of fore shocks to predict the time and location of large earthquakes more accurately. Moreover, instead of average, the peak values of these quantities are helpful

  15. Simple yet accurate noncontact device for measuring the radius of curvature of a spherical mirror

    SciTech Connect

    Spiridonov, Maxim; Toebaert, David

    2006-09-10

    An easily reproducible device is demonstrated to be capable of measuring the radii of curvature of spherical mirrors, both convex and concave, without resorting to high-end interferometric or tactile devices. The former are too elaborate for our purposes,and the latter cannot be used due to the delicate nature of the coatings applied to mirrors used in high-power CO2 laser applications. The proposed apparatus is accurate enough to be useful to anyone using curved optics and needing a quick way to assess the values of the radii of curvature, be it for entrance quality control or trouble shooting an apparently malfunctioning optical system. Specifically, the apparatus was designed for checking 50 mm diameter resonator(typically flat or tens of meters concave) and telescope (typically some meters convex and concave) mirrors for a high-power CO2 laser, but it can easily be adapted to any other type of spherical mirror by a straightforward resizing.

  16. New insights for accurate chemically specific measurements of slow diffusing molecules

    NASA Astrophysics Data System (ADS)

    Hou, Jianbo; Madsen, Louis A.

    2013-02-01

    Investigating the myriad features of molecular transport in materials yields fundamental information for understanding processes such as ion conduction, chemical reactions, and phase transitions. Molecular transport especially impacts the performance of ion-containing liquids and polymeric materials when used as electrolytes and separation media, with applications encompassing battery electrolytes, reverse-osmosis membranes, mechanical transducers, and fuel cells. Nuclear magnetic resonance (NMR) provides a unique probe of molecular translations by allowing measurement of all mobile species via spectral selectivity, access to a broad range of transport coefficients, probing of any material direction, and investigation of variable lengthscales in a material, thus, tying morphology to transport. Here, we present new concepts to test for and guarantee robust diffusion measurements. We first employ a standard pulsed-field-gradient (PFG) calibration protocol using 2H2O and obtain expected results, but we observe crippling artifacts when measuring 1H-glycerol diffusion with the same experimental parameters. A mathematical analysis of 2H2O and glycerol signals in the presence of PFG transients show tight agreement with experimental observations. These analyses lead to our principal findings that (1) negligible artifacts observed with low gyromagnetic ratio (γ) nuclei may become dominant when observing high γ nuclei, and (2) reducing the sample dimension along the gradient direction predictably reduces non-ideal behaviors of NMR signals. We further provide a useful quantitative strategy for error minimization when measuring diffusing species slower than the one used for gradient calibration.

  17. Root resistance to cavitation is accurately measured using a centrifuge technique.

    PubMed

    Pratt, R B; MacKinnon, E D; Venturas, M D; Crous, C J; Jacobsen, A L

    2015-02-01

    Plants transport water under negative pressure and this makes their xylem vulnerable to cavitation. Among plant organs, root xylem is often highly vulnerable to cavitation due to water stress. The use of centrifuge methods to study organs, such as roots, that have long vessels are hypothesized to produce erroneous estimates of cavitation resistance due to the presence of open vessels through measured samples. The assumption that roots have long vessels may be premature since data for root vessel length are sparse; moreover, recent studies have not supported the existence of a long-vessel artifact for stems when a standard centrifuge technique was used. We examined resistance to cavitation estimated using a standard centrifuge technique and compared these values with native embolism measurements for roots of seven woody species grown in a common garden. For one species we also measured vulnerability using single-vessel air injection. We found excellent agreement between root native embolism and the levels of embolism measured using a centrifuge technique, and with air-seeding estimates from single-vessel injection. Estimates of cavitation resistance measured from centrifuge curves were biologically meaningful and were correlated with field minimum water potentials, vessel diameter (VD), maximum xylem-specific conductivity (Ksmax) and vessel length. Roots did not have unusually long vessels compared with stems; moreover, root vessel length was not correlated to VD or to the vessel length of stems. These results suggest that root cavitation resistance can be accurately and efficiently measured using a standard centrifuge method and that roots are highly vulnerable to cavitation. The role of root cavitation resistance in determining drought tolerance of woody species deserves further study, particularly in the context of climate change.

  18. An algorithm for selecting the most accurate protocol for contact angle measurement by drop shape analysis.

    PubMed

    Xu, Z N

    2014-12-01

    In this study, an error analysis is performed to study real water drop images and the corresponding numerically generated water drop profiles for three widely used static contact angle algorithms: the circle- and ellipse-fitting algorithms and the axisymmetric drop shape analysis-profile (ADSA-P) algorithm. The results demonstrate the accuracy of the numerically generated drop profiles based on the Laplace equation. A significant number of water drop profiles with different volumes, contact angles, and noise levels are generated, and the influences of the three factors on the accuracies of the three algorithms are systematically investigated. The results reveal that the above-mentioned three algorithms are complementary. In fact, the circle- and ellipse-fitting algorithms show low errors and are highly resistant to noise for water drops with small/medium volumes and contact angles, while for water drop with large volumes and contact angles just the ADSA-P algorithm can meet accuracy requirement. However, this algorithm introduces significant errors in the case of small volumes and contact angles because of its high sensitivity to noise. The critical water drop volumes of the circle- and ellipse-fitting algorithms corresponding to a certain contact angle error are obtained through a significant amount of computation. To improve the precision of the static contact angle measurement, a more accurate algorithm based on a combination of the three algorithms is proposed. Following a systematic investigation, the algorithm selection rule is described in detail, while maintaining the advantages of the three algorithms and overcoming their deficiencies. In general, static contact angles over the entire hydrophobicity range can be accurately evaluated using the proposed algorithm. The ease of erroneous judgment in static contact angle measurements is avoided. The proposed algorithm is validated by a static contact angle evaluation of real and numerically generated water drop

  19. An algorithm for selecting the most accurate protocol for contact angle measurement by drop shape analysis

    NASA Astrophysics Data System (ADS)

    Xu, Z. N.

    2014-12-01

    In this study, an error analysis is performed to study real water drop images and the corresponding numerically generated water drop profiles for three widely used static contact angle algorithms: the circle- and ellipse-fitting algorithms and the axisymmetric drop shape analysis-profile (ADSA-P) algorithm. The results demonstrate the accuracy of the numerically generated drop profiles based on the Laplace equation. A significant number of water drop profiles with different volumes, contact angles, and noise levels are generated, and the influences of the three factors on the accuracies of the three algorithms are systematically investigated. The results reveal that the above-mentioned three algorithms are complementary. In fact, the circle- and ellipse-fitting algorithms show low errors and are highly resistant to noise for water drops with small/medium volumes and contact angles, while for water drop with large volumes and contact angles just the ADSA-P algorithm can meet accuracy requirement. However, this algorithm introduces significant errors in the case of small volumes and contact angles because of its high sensitivity to noise. The critical water drop volumes of the circle- and ellipse-fitting algorithms corresponding to a certain contact angle error are obtained through a significant amount of computation. To improve the precision of the static contact angle measurement, a more accurate algorithm based on a combination of the three algorithms is proposed. Following a systematic investigation, the algorithm selection rule is described in detail, while maintaining the advantages of the three algorithms and overcoming their deficiencies. In general, static contact angles over the entire hydrophobicity range can be accurately evaluated using the proposed algorithm. The ease of erroneous judgment in static contact angle measurements is avoided. The proposed algorithm is validated by a static contact angle evaluation of real and numerically generated water drop

  20. Measuring solar reflectance Part I: Defining a metric that accurately predicts solar heat gain

    SciTech Connect

    Levinson, Ronnen; Akbari, Hashem; Berdahl, Paul

    2010-05-14

    Solar reflectance can vary with the spectral and angular distributions of incident sunlight, which in turn depend on surface orientation, solar position and atmospheric conditions. A widely used solar reflectance metric based on the ASTM Standard E891 beam-normal solar spectral irradiance underestimates the solar heat gain of a spectrally selective 'cool colored' surface because this irradiance contains a greater fraction of near-infrared light than typically found in ordinary (unconcentrated) global sunlight. At mainland U.S. latitudes, this metric RE891BN can underestimate the annual peak solar heat gain of a typical roof or pavement (slope {le} 5:12 [23{sup o}]) by as much as 89 W m{sup -2}, and underestimate its peak surface temperature by up to 5 K. Using R{sub E891BN} to characterize roofs in a building energy simulation can exaggerate the economic value N of annual cool-roof net energy savings by as much as 23%. We define clear-sky air mass one global horizontal ('AM1GH') solar reflectance R{sub g,0}, a simple and easily measured property that more accurately predicts solar heat gain. R{sub g,0} predicts the annual peak solar heat gain of a roof or pavement to within 2 W m{sup -2}, and overestimates N by no more than 3%. R{sub g,0} is well suited to rating the solar reflectances of roofs, pavements and walls. We show in Part II that R{sub g,0} can be easily and accurately measured with a pyranometer, a solar spectrophotometer or version 6 of the Solar Spectrum Reflectometer.

  1. Accurate Measurement of Canal Length during Root Canal Treatment: An In Vivo Study

    PubMed Central

    Sadaf, Durre; Ahmad, Muhammad Zubair

    2015-01-01

    Objectives: To assess the consistency and accuracy of Electronic Apex Locator (EAL) (Root ZXII) in individual canals and its association with other clinical variables. Study Design: Cross-Sectional study. Place of study: Dental section of the Aga Khan University Hospital, Karachi, Pakistan. Materials and Methods: Working length was measured by EAL in 180 patients requiring endodontic therapy in molar and premolar teeth. The effects of clinical variables e.g. gender and pulpal status on the consistency and accuracy of EAL were recorded. Performance of apex locator was considered “Consistent” when the scale bar was stable and moved only in correspondence to the movement of file in the root canal. Accuracy was determined by inserting the file at the working length determined by the EAL and periapical view of radiograph was taken using paralleling technique. Estimated working length was considered accurate when the file tip was located 0-2mm short of the radiographic apex. If the file was overextended from the radiographic apex, it showed dysfunction of the EAL. Results: Consistency of EAL was found 97.6% in distobuccal canals, 91.1% in palatal canals, 73.7% in mesiolingual canals, 83.3% in mesiobuccal and 80.2% in distal canals. Accuracy of EAL was 91.4% in mesiolingual canal, 92% in mesiobuccal, and 90.2% in Palatal and 93.2% in distal canal. Conclusion: Consistency of electronic apex locator vary in different canals, however consistent measurements are highly accurate. No significant association was found between other clinical variables with the consistency and accuracy of EAL.

  2. Stratus optical coherence tomogram III: a novel, reliable and accurate way to measure corneal thickness.

    PubMed

    Madgula, Indira M; Kotta, Satish

    2007-01-01

    The commercially available optical coherence tomogram (Stratus OCT III) designed for posterior segment imaging can be used for central corneal thickness (CCT) measurement. The aim of the study was to determine the accuracy and reliability of CCT measurements using Stratus OCT III versus ultrasound pachymetry. CCT using Stratus OCT III (CCT oct) was taken and averaged. The focusing system had to be defocused near the maximum to relay the image of the OCT beam onto the cornea. CCT was then determined using the ultrasound pachymeter (CCT usg). Thirty white volunteers (12 male, 18 female) participated in this study. The mean CCToct was 522.33+/-34.44 microns. The mean CCTusg was 547.37+/-33.08 microns. The mean differences between CCTusg and CCToct was 25.04+/-11.67. CCT usg was found to be highly correlated with CCToct (P < 0.001) The relation can be represented by the equation. CCToct = 0.98 (CCTusg) - 13.9. The Stratus OCT III gave reliable readings of CCT and is a novel, reliable and accurate way to measure CCT.

  3. Indirect viscosimetric method is less accurate than ektacytometry for the measurement of red blood cell deformability.

    PubMed

    Vent-Schmidt, Jens; Waltz, Xavier; Pichon, Aurélien; Hardy-Dessources, Marie-Dominique; Romana, Marc; Connes, Philippe

    2015-01-01

    The aim of this study was to test the accuracy of viscosimetric method to estimate the red blood cell (RBC) deformability properties. Thirty-three subjects were enrolled in this study: 6 healthy subjects (AA), 11 patients with sickle cell-hemoglobin C disease (SC) and 16 patients with sickle cell anemia (SS). Two methods were used to assess RBC deformability: 1) indirect viscosimetric method and 2) ektacytometry. The indirect viscosimetric method was based on the Dintenfass equation where blood viscosity, plasma viscosity and hematocrit are measured and used to calculate an index of RBC rigidity (Tk index). The RBC deformability/rigidity of the three groups was compared using the two methods. Tk index was not different between SS and SC patients and the two groups had higher values than AA group. When ektacytometry was used, RBC deformability was lower in SS and SC groups compared to the AA group and SS and SC patients were different. Although the two measures of RBC deformability were correlated, the association was not very high. Bland and Altman analysis demonstrated a 3.25 bias suggesting a slight difference between the two methods. In addition, the limit of agreement represented 28% (>15%) of the mean values of RBC deformability, showing no interchangeability between the two methods. In conclusion, measuring RBC deformability by indirect viscosimetry is less accurate than by ektacytometry, which is considered the gold standard.

  4. High-Frequency CTD Measurements for Accurate GPS/acoustic Sea-floor Crustal Deformation Measurement System

    NASA Astrophysics Data System (ADS)

    Tadokoro, K.; Yasuda, K.; Taniguchi, S.; Uemura, Y.; Matsuhiro, K.

    2015-12-01

    The GPS/acoustic sea-floor crustal deformation measurement system has developed as a useful tool to observe tectonic deformation especially at subduction zones. One of the factors preventing accurate GPS/acoustic sea-floor crustal deformation measurement is horizontal heterogeneity of sound speed in the ocean. It is therefore necessary to measure the gradient directly from sound speed structure. We report results of high-frequency CTD measurements using Underway CTD (UCTD) in the Kuroshio region. We perform the UCTD measurements on May 2nd, 2015 at two stations (TCA and TOA) above the sea-floor benchmarks installed across the Nankai Trough, off the south-east of Kii Peninsula, middle Japan. The number of measurement points is six at each station along circles with a diameter of 1.8 nautical miles around the sea-floor benchmark. The stations TCA and TOA are located on the edge and the interior of the Kuroshio current, respectively, judging from difference in sea water density measured at the two stations, as well as a satellite image of sea-surface temperature distribution. We detect a sound speed gradient of high speeds in the southern part and low speeds in the northern part at the two stations. At the TCA station, the gradient is noticeable down to 300 m in depth; the maximum difference in sound speed is +/- 5 m/s. The sound speed difference is as small as +/- 1.3 m/s at depths below 300 m, which causes seafloor benchmark positioning error as large as 1 m. At the TOA station, the gradient is extremely small down to 100 m in depth. The maximum difference in sound speed is less than +/- 0.3 m/s that is negligible small for seafloor benchmark positioning error. Clear gradient of high speed is observed to the depths; the maximum difference in sound speed is +/- 0.8-0.9 m/s, causing seafloor benchmark positioning error of several tens centimeters. The UCTD measurement is effective tool to detect sound speed gradient. We establish a method for accurate sea

  5. Experimental noiseless linear amplification using weak measurements

    NASA Astrophysics Data System (ADS)

    Ho, Joseph; Boston, Allen; Palsson, Matthew; Pryde, Geoff

    2016-09-01

    The viability of quantum communication schemes rely on sending quantum states of light over long distances. However, transmission loss can degrade the signal strength, adding noise. Heralded noiseless amplification of a quantum signal can provide a solution by enabling longer direct transmission distances and by enabling entanglement distillation. The central idea of heralded noiseless amplification—a conditional modification of the probability distribution over photon number of an optical quantum state—is suggestive of a parallel with weak measurement: in a weak measurement, learning partial information about an observable leads to a conditional back-action of a commensurate size. Here we experimentally investigate the application of weak, or variable-strength, measurements to the task of heralded amplification, by using a quantum logic gate to weakly couple a small single-optical-mode quantum state (the signal) to an ancilla photon (the meter). The weak measurement is carried out by choosing the measurement basis of the meter photon and, by conditioning on the meter outcomes, the signal is amplified. We characterise the gain of the amplifier as a function of the measurement strength, and use interferometric methods to show that the operation preserves the coherence of the signal.

  6. Experimental research of digital holographic microscopic measuring

    NASA Astrophysics Data System (ADS)

    Zhu, Xueliang; Chen, Feifei; Li, Jicheng

    2013-06-01

    Digital holography is a new imaging technique, which is developed on the base of optical holography, Digital processing, and Computer techniques. It is using CCD instead of the conventional silver to record hologram, and then reproducing the 3D contour of the object by the way of computer simulation. Compared with the traditional optical holographic, the whole process is of simple measuring, lower production cost, faster the imaging speed, and with the advantages of non-contact real-time measurement. At present, it can be used in the fields of the morphology detection of tiny objects, micro deformation analysis, and biological cells shape measurement. It is one of the research hot spot at home and abroad. This paper introduced the basic principles and relevant theories about the optical holography and Digital holography, and researched the basic questions which influence the reproduce images in the process of recording and reconstructing of the digital holographic microcopy. In order to get a clear digital hologram, by analyzing the optical system structure, we discussed the recording distance and of the hologram. On the base of the theoretical studies, we established a measurement and analyzed the experimental conditions, then adjusted them to the system. To achieve a precise measurement of tiny object in three-dimension, we measured MEMS micro device for example, and obtained the reproduction three-dimensional contour, realized the three dimensional profile measurement of tiny object. According to the experiment results consider: analysis the reference factors between the zero-order term and a pair of twin-images by the choice of the object light and the reference light and the distance of the recording and reconstructing and the characteristics of reconstruction light on the measurement, the measurement errors were analyzed. The research result shows that the device owns certain reliability.

  7. Experimental Techniques for Thermodynamic Measurements of Ceramics

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Putnam, Robert L.; Navrotsky, Alexandra

    1999-01-01

    Experimental techniques for thermodynamic measurements on ceramic materials are reviewed. For total molar quantities, calorimetry is used. Total enthalpies are determined with combustion calorimetry or solution calorimetry. Heat capacities and entropies are determined with drop calorimetry, differential thermal methods, and adiabatic calorimetry . Three major techniques for determining partial molar quantities are discussed. These are gas equilibration techniques, Knudsen cell methods, and electrochemical techniques. Throughout this report, issues unique to ceramics are emphasized. Ceramic materials encompass a wide range of stabilities and this must be considered. In general data at high temperatures is required and the need for inert container materials presents a particular challenge.

  8. CALIBRATION OF X-RAY IMAGING DEVICES FOR ACCURATE INTENSITY MEASUREMENT

    SciTech Connect

    Haugh, M J; Charest, M R; Ross, P W; Lee, J J; Schneider, M B; Palmer, N E; Teruya, A T

    2012-02-16

    National Security Technologies (NSTec) has developed calibration procedures for X-ray imaging systems. The X-ray sources that are used for calibration are both diode type and diode/fluorescer combinations. Calibrating the X-ray detectors is key to accurate calibration of the X-ray sources. Both energy dispersive detectors and photodiodes measuring total flux were used. We have developed calibration techniques for the detectors using radioactive sources that are traceable to the National Institute of Standards and Technology (NIST). The German synchrotron at Physikalische Technische Bundestalt (PTB) is used to calibrate silicon photodiodes over the energy range from 50 eV to 60 keV. The measurements on X-ray cameras made using the NSTec X-ray sources have included quantum efficiency averaged over all pixels, camera counts per photon per pixel, and response variation across the sensor. The instrumentation required to accomplish the calibrations is described. X-ray energies ranged from 720 eV to 22.7 keV. The X-ray sources produce narrow energy bands, allowing us to determine the properties as a function of X-ray energy. The calibrations were done for several types of imaging devices. There were back illuminated and front illuminated CCD (charge coupled device) sensors, and a CID (charge injection device) type camera. The CCD and CID camera types differ significantly in some of their properties that affect the accuracy of X-ray intensity measurements. All cameras discussed here are silicon based. The measurements of quantum efficiency variation with X-ray energy are compared to models for the sensor structure. Cameras that are not back-thinned are compared to those that are.

  9. Accurate, in vivo NIR measurement of skeletal muscle oxygenation through fat

    NASA Astrophysics Data System (ADS)

    Jin, Chunguang; Zou, Fengmei; Ellerby, Gwenn E. C.; Scott, Peter; Peshlov, Boyan; Soller, Babs R.

    2010-02-01

    Noninvasive near infrared (NIR) spectroscopic measurement of muscle oxygenation requires the penetration of light through overlying skin and fat layers. We have previously demonstrated a dual-light source design and orthogonalization algorithm that corrects for inference from skin absorption and fat scattering. To achieve accurate muscle oxygen saturation (SmO2) measurement, one must select the appropriate source-detector distance (SD) to completely penetrate the fat layer. Methods: Six healthy subjects were supine for 15min to normalize tissue oxygenation across the body. NIR spectra were collected from the calf, shoulder, lower and upper thigh muscles with long SD distances of 30mm, 35mm, 40mm and 45mm. Spectral preprocessing with the short SD (3mm) spectrum preceded SmO2 calculation with a Taylor series expansion method. Three-way ANOVA was used to compare SmO2 values over varying fat thickness, subjects and SD distances. Results: Overlying fat layers varied in thickness from 4.9mm to 19.6mm across all subjects. SmO2 measured at the four locations were comparable for each subject (p=0.133), regardless of fat thickness and SD distance. SmO2 (mean+/-std dev) measured at calf, shoulder, low and high thigh were 62+/-3%, 59+/-8%, 61+/-2%, 61+/-4% respectively for SD distance of 30mm. In these subjects no significant influence of SD was observed (p=0.948). Conclusions: The results indicate that for our sensor design a 30mm SD is sufficient to penetrate through a 19mm fat layer and that orthogonalization with short SD effectively removed spectral interference from fat to result in a reproducible determination of SmO2.

  10. An Accurate Non-Cooperative Method for Measuring Textureless Spherical Target Based on Calibrated Lasers

    PubMed Central

    Wang, Fei; Dong, Hang; Chen, Yanan; Zheng, Nanning

    2016-01-01

    Strong demands for accurate non-cooperative target measurement have been arising recently for the tasks of assembling and capturing. Spherical objects are one of the most common targets in these applications. However, the performance of the traditional vision-based reconstruction method was limited for practical use when handling poorly-textured targets. In this paper, we propose a novel multi-sensor fusion system for measuring and reconstructing textureless non-cooperative spherical targets. Our system consists of four simple lasers and a visual camera. This paper presents a complete framework of estimating the geometric parameters of textureless spherical targets: (1) an approach to calibrate the extrinsic parameters between a camera and simple lasers; and (2) a method to reconstruct the 3D position of the laser spots on the target surface and achieve the refined results via an optimized scheme. The experiment results show that our proposed calibration method can obtain a fine calibration result, which is comparable to the state-of-the-art LRF-based methods, and our calibrated system can estimate the geometric parameters with high accuracy in real time. PMID:27941705

  11. Accurate measurement of volume and shape of resting and activated blood platelets from light scattering

    NASA Astrophysics Data System (ADS)

    Moskalensky, Alexander E.; Yurkin, Maxim A.; Konokhova, Anastasiya I.; Strokotov, Dmitry I.; Nekrasov, Vyacheslav M.; Chernyshev, Andrei V.; Tsvetovskaya, Galina A.; Chikova, Elena D.; Maltsev, Valeri P.

    2013-01-01

    We introduce a novel approach for determination of volume and shape of individual blood platelets modeled as an oblate spheroid from angle-resolved light scattering with flow-cytometric technique. The light-scattering profiles (LSPs) of individual platelets were measured with the scanning flow cytometer and the platelet characteristics were determined from the solution of the inverse light-scattering problem using the precomputed database of theoretical LSPs. We revealed a phenomenon of parameter compensation, which is partly explained in the framework of anomalous diffraction approximation. To overcome this problem, additional a priori information on the platelet refractive index was used. It allowed us to determine the size of each platelet with subdiffraction precision and independent of the particular value of the platelet aspect ratio. The shape (spheroidal aspect ratio) distributions of platelets showed substantial differences between native and activated by 10 μM adenosine diphosphate samples. We expect that the new approach may find use in hematological analyzers for accurate measurement of platelet volume distribution and for determination of the platelet activation efficiency.

  12. An Accurate Non-Cooperative Method for Measuring Textureless Spherical Target Based on Calibrated Lasers.

    PubMed

    Wang, Fei; Dong, Hang; Chen, Yanan; Zheng, Nanning

    2016-12-09

    Strong demands for accurate non-cooperative target measurement have been arising recently for the tasks of assembling and capturing. Spherical objects are one of the most common targets in these applications. However, the performance of the traditional vision-based reconstruction method was limited for practical use when handling poorly-textured targets. In this paper, we propose a novel multi-sensor fusion system for measuring and reconstructing textureless non-cooperative spherical targets. Our system consists of four simple lasers and a visual camera. This paper presents a complete framework of estimating the geometric parameters of textureless spherical targets: (1) an approach to calibrate the extrinsic parameters between a camera and simple lasers; and (2) a method to reconstruct the 3D position of the laser spots on the target surface and achieve the refined results via an optimized scheme. The experiment results show that our proposed calibration method can obtain a fine calibration result, which is comparable to the state-of-the-art LRF-based methods, and our calibrated system can estimate the geometric parameters with high accuracy in real time.

  13. Accurately measuring volume of soil samples using low cost Kinect 3D scanner

    NASA Astrophysics Data System (ADS)

    van der Sterre, B.; Hut, R.; Van De Giesen, N.

    2012-12-01

    The 3D scanner of the Kinect game controller can be used to increase the accuracy and efficiency of determining in situ soil moisture content. Soil moisture is one of the principal hydrological variables in both the water and energy interactions between soil and atmosphere. Current in situ measurements of soil moisture either rely on indirect measurements (of electromagnetic constants or heat capacity) or on physically taking a sample and weighing it in a lab. The bottleneck in accurately retrieving soil moisture using samples is the determining of the volume of the sample. Currently this is mostly done by the very time consuming "sand cone method" in which the volume were the sample used to sit is filled with sand. We show that 3D scanner that is part of the $150 game controller extension "Kinect" can be used to make 3D scans before and after taking the sample. The accuracy of this method is tested by scanning forms of known volume. This method is less time consuming and less error-prone than using a sand cone.

  14. Accurately measuring volume of soil samples using low cost Kinect 3D scanner

    NASA Astrophysics Data System (ADS)

    van der Sterre, Boy-Santhos; Hut, Rolf; van de Giesen, Nick

    2013-04-01

    The 3D scanner of the Kinect game controller can be used to increase the accuracy and efficiency of determining in situ soil moisture content. Soil moisture is one of the principal hydrological variables in both the water and energy interactions between soil and atmosphere. Current in situ measurements of soil moisture either rely on indirect measurements (of electromagnetic constants or heat capacity) or on physically taking a sample and weighing it in a lab. The bottleneck in accurately retrieving soil moisture using samples is the determining of the volume of the sample. Currently this is mostly done by the very time consuming "sand cone method" in which the volume were the sample used to sit is filled with sand. We show that 3D scanner that is part of the 150 game controller extension "Kinect" can be used to make 3D scans before and after taking the sample. The accuracy of this method is tested by scanning forms of known volume. This method is less time consuming and less error-prone than using a sand cone.

  15. Accurate measurement of interferometer group delay using field-compensated scanning white light interferometer.

    PubMed

    Wan, Xiaoke; Wang, Ji; Ge, Jian

    2010-10-10

    Interferometers are key elements in radial velocity (RV) experiments in astronomy observations, and accurate calibration of the group delay of an interferometer is required for high precision measurements. A novel field-compensated white light scanning Michelson interferometer is introduced as an interferometer calibration tool. The optical path difference (OPD) scanning was achieved by translating a compensation prism, such that even if the light source were in low spatial coherence, the interference stays spatially phase coherent over a large interferometer scanning range. In the wavelength region of 500-560 nm, a multimode fiber-coupled LED was used as the light source, and high optical efficiency was essential in elevating the signal-to-noise ratio of the interferogram signal. The achromatic OPD scanning required a one-time calibration, and two methods using dual-laser wavelength references and an iodine absorption spectrum reference were employed and cross-verified. In an experiment measuring the group delay of a fixed Michelson interferometer, Fourier analysis was employed to process the interferogram data. The group delay was determined at an accuracy of 1×10(-5), and the phase angle precision was typically 2.5×10(-6) over the wide wavelength region.

  16. Highly accurate isotope composition measurements by a miniature laser ablation mass spectrometer designed for in situ investigations on planetary surfaces

    NASA Astrophysics Data System (ADS)

    Riedo, A.; Meyer, S.; Heredia, B.; Neuland, M. B.; Bieler, A.; Tulej, M.; Leya, I.; Iakovleva, M.; Mezger, K.; Wurz, P.

    2013-10-01

    An experimental procedure for precise and accurate measurements of isotope abundances by a miniature laser ablation mass spectrometer for space research is described. The measurements were conducted on different untreated NIST standards and galena samples by applying pulsed UV laser radiation (266 nm, 3 ns and 20 Hz) for ablation, atomisation, and ionisation of the sample material. Mass spectra of released ions are measured by a reflectron-type time-of-flight mass analyser. A computer controlled performance optimiser was used to operate the system at maximum ion transmission and mass resolution. At optimal experimental conditions, the best relative accuracy and precision achieved for Pb isotope compositions are at the per mill level and were obtained in a range of applied laser irradiances and a defined number of accumulated spectra. A similar relative accuracy and precision was achieved in the study of Pb isotope compositions in terrestrial galena samples. The results for the galena samples are similar to those obtained with a thermal ionisation mass spectrometer (TIMS). The studies of the isotope composition of other elements yielded relative accuracy and precision at the per mill level too, with characteristic instrument parameters for each element. The relative accuracy and precision of the measurements is degrading with lower element/isotope concentration in a sample. For the elements with abundances below 100 ppm these values drop to the percent level. Depending on the isotopic abundances of Pb in minerals, 207Pb/206Pb ages with accuracy in the range of tens of millions of years can be achieved.

  17. Accurate measurement of the x-ray coherent scattering form factors of tissues

    NASA Astrophysics Data System (ADS)

    King, Brian W.

    energy-sensitive detector. It is shown that F coh can be measured directly by computing the ratio of two spectra: one, measured at a given scattering angle and the other, the direct transmission spectrum with no scattering. Experiments were constructed on this principle and used to measure Fcoh for water, fat and several types of plastics. A 121 kVp x-ray spectrum and seven different scattering angles between 1.75° and 15° were used, resulting in a measurable range of x between 0.5 and 9.5 nm-1. These are the first measurements of coherent scattering form factors made without the need for a scaling factor. Resolution in x varies between 10% at small scattering angles and 2% for larger scattering angles. Accuracy in F coh is shown to be strongly dependent on the precision of the experimental geometry and varies between 5% and 15%. The average absolute relative difference between repeated measurements was ˜ 5%. The agreement between the energy-dispersive and angle-dispersive techniques is shown to be quite good, considering the low resolution of the angle-dispersive measurement. The average absolute relative difference in F coh between the angle-dispersive measurement with a 70 kVp spectrum and the energy-dispersive measurement was ˜ 12%.

  18. Development of Ground-Based DIAL Techniques for High Accurate Measurements of CO2 Concentration Profiles in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Nagasawa, C.; Abo, M.; Shibata, Y.; Nagai, T.; Nakazato, M.; Sakai, T.; Tsukamoto, M.; Sakaizawa, D.

    2009-12-01

    High-accurate vertical carbon dioxide (CO2) profiles are highly desirable in the inverse method to improve quantification and understanding of the global sink and source of CO2, and also global climate change. We have developed a ground based 1.6μm differential absorption lidar (DIAL) to achieve high accurate measurements of vertical CO2 profiles in the atmosphere. The DIAL system is constructed from the optical parametric oscillation(OPO) transmitter and the direct detection receiving system that included a near-infrared photomultiplier tube operating at photon counting mode (Fig.1). The primitive DIAL measurement was achieved successfully the vertical CO2 profile up to 7 km altitude with an error less than 1.0 % by integration time of 50 minutes and vertical resolution of 150m. We develop the next generation 1.6 μm DIAL that can measure simultaneously the vertical CO2 concentration, temperature and pressure profiles in the atmosphere. The characteristics of the 1.6 μm DIALs of the primitive and next generations are shown in Table 1. As the spectra of absorption lines of any molecules are influenced basically by the temperature and pressure in the atmosphere, it is important to measure them simultaneously so that the better accuracy of the DIAL measurement may be realized. Moreover, the value of the retrieved CO2 concentration will be improved remarkably by processing the iteration assignment of CO2 concentration, temperature and pressure which measured by DIAL techniques. This work was financially supported by the Japan EOS Promotion Program by the MEXT Japan and System Development Program for Advanced Measurement and Analysis by the JST. Reference D. Sakaisawa et al., Development of a 1.6μm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and photon-counting detector for the vertical CO2 profile, Applied Optics, Vol.48, No.4, pp.748-757, 2009. Fig. 1 Experimental setup of the 1.6 μm CO2 DIAL. Comparison of primitive

  19. Accurate 3D kinematic measurement of temporomandibular joint using X-ray fluoroscopic images

    NASA Astrophysics Data System (ADS)

    Yamazaki, Takaharu; Matsumoto, Akiko; Sugamoto, Kazuomi; Matsumoto, Ken; Kakimoto, Naoya; Yura, Yoshiaki

    2014-04-01

    Accurate measurement and analysis of 3D kinematics of temporomandibular joint (TMJ) is very important for assisting clinical diagnosis and treatment of prosthodontics and orthodontics, and oral surgery. This study presents a new 3D kinematic measurement technique of the TMJ using X-ray fluoroscopic images, which can easily obtain the TMJ kinematic data in natural motion. In vivo kinematics of the TMJ (maxilla and mandibular bone) is determined using a feature-based 2D/3D registration, which uses beads silhouette on fluoroscopic images and 3D surface bone models with beads. The 3D surface models of maxilla and mandibular bone with beads were created from CT scans data of the subject using the mouthpiece with the seven strategically placed beads. In order to validate the accuracy of pose estimation for the maxilla and mandibular bone, computer simulation test was performed using five patterns of synthetic tantalum beads silhouette images. In the clinical applications, dynamic movement during jaw opening and closing was conducted, and the relative pose of the mandibular bone with respect to the maxilla bone was determined. The results of computer simulation test showed that the root mean square errors were sufficiently smaller than 1.0 mm and 1.0 degree. In the results of clinical application, during jaw opening from 0.0 to 36.8 degree of rotation, mandibular condyle exhibited 19.8 mm of anterior sliding relative to maxillary articular fossa, and these measurement values were clinically similar to the previous reports. Consequently, present technique was thought to be suitable for the 3D TMJ kinematic analysis.

  20. Accurate measurement of respiratory airway wall thickness in CT images using a signal restoration technique

    NASA Astrophysics Data System (ADS)

    Park, Sang Joon; Kim, Tae Jung; Kim, Kwang Gi; Lee, Sang Ho; Goo, Jin Mo; Kim, Jong Hyo

    2008-03-01

    Airway wall thickness (AWT) is an important bio-marker for evaluation of pulmonary diseases such as chronic bronchitis, bronchiectasis. While an image-based analysis of the airway tree can provide precise and valuable airway size information, quantitative measurement of AWT in Multidetector-Row Computed Tomography (MDCT) images involves various sources of error and uncertainty. So we have developed an accurate AWT measurement technique for small airways with three-dimensional (3-D) approach. To evaluate performance of these techniques, we used a set of acryl tube phantom was made to mimic small airways to have three different sizes of wall diameter (4.20, 1.79, 1.24 mm) and wall thickness (1.84, 1.22, 0.67 mm). The phantom was imaged with MDCT using standard reconstruction kernel (Sensation 16, Siemens, Erlangen). The pixel size was 0.488 mm × 0.488 mm × 0.75 mm in x, y, and z direction respectively. The images were magnified in 5 times using cubic B-spline interpolation, and line profiles were obtained for each tube. To recover faithful line profile from the blurred images, the line profiles were deconvolved with a point spread kernel of the MDCT which was estimated using the ideal tube profile and image line profile. The inner diameter, outer diameter, and wall thickness of each tube were obtained with full-width-half-maximum (FWHM) method for the line profiles before and after deconvolution processing. Results show that significant improvement was achieved over the conventional FWHM method in the measurement of AWT.

  1. Experimental Measurement of Micrometeoroid-Produced Neutrals

    NASA Astrophysics Data System (ADS)

    Collette, A.; Sternovsky, Z.; Horanyi, M.; Munsat, T. L.

    2013-12-01

    We describe the first laboratory measurement of vapor produced by simulated micrometeoroid bombardment. Exospheric gas measurements remain one of the outstanding accomplishments of the Apollo era, and are a clear scientific goal for future exploration of airless objects. New in-situ observations of the surface-bounded exosphere (SBE) at Mercury by MESSENGER, and the Moon by LRO/LAMP, have highlighted the uncertainty surrounding the role of micrometeoroid impacts in sustaining planetary SBEs. In a recent series of experiments, the quantity of neutral molecules generated by impacts of simulated micrometeoroids (0.1-1 micron radius, 1-10 km/s speed) was measured in the lab using a fast ionization gauge inside an ultrahigh-vacuum system. The quantity of neutrals released was found to be consistent with a power law N = mv^a in projectile speed v, mass m and exponent a ~ 2.4 We present these experimental results and discuss their implications for the upcoming LADEE mission, which carries both neutral mass and optical spectrometers for exospheric measurements, capable of identifying micrometeoroid-sourced gases.

  2. Enabling high grayscale resolution displays and accurate response time measurements on conventional computers.

    PubMed

    Li, Xiangrui; Lu, Zhong-Lin

    2012-02-29

    Display systems based on conventional computer graphics cards are capable of generating images with 8-bit gray level resolution. However, most experiments in vision research require displays with more than 12 bits of luminance resolution. Several solutions are available. Bit++ (1) and DataPixx (2) use the Digital Visual Interface (DVI) output from graphics cards and high resolution (14 or 16-bit) digital-to-analog converters to drive analog display devices. The VideoSwitcher (3) described here combines analog video signals from the red and blue channels of graphics cards with different weights using a passive resister network (4) and an active circuit to deliver identical video signals to the three channels of color monitors. The method provides an inexpensive way to enable high-resolution monochromatic displays using conventional graphics cards and analog monitors. It can also provide trigger signals that can be used to mark stimulus onsets, making it easy to synchronize visual displays with physiological recordings or response time measurements. Although computer keyboards and mice are frequently used in measuring response times (RT), the accuracy of these measurements is quite low. The RTbox is a specialized hardware and software solution for accurate RT measurements. Connected to the host computer through a USB connection, the driver of the RTbox is compatible with all conventional operating systems. It uses a microprocessor and high-resolution clock to record the identities and timing of button events, which are buffered until the host computer retrieves them. The recorded button events are not affected by potential timing uncertainties or biases associated with data transmission and processing in the host computer. The asynchronous storage greatly simplifies the design of user programs. Several methods are available to synchronize the clocks of the RTbox and the host computer. The RTbox can also receive external triggers and be used to measure RT with respect

  3. An easy way to measure accurately the direct magnetoelectric voltage coefficient of thin film devices

    NASA Astrophysics Data System (ADS)

    Poullain, Gilles; More-Chevalier, Joris; Cibert, Christophe; Bouregba, Rachid

    2017-01-01

    TbxDy1-xFe2/Pt/Pb(Zrx, Ti1-x)O3 thin films were grown on Pt/TiO2/SiO2/Si substrate by multi-target sputtering. The magnetoelectric voltage coefficient αΗΜΕ was determined at room temperature using a lock-in amplifier. By adding, in series in the circuit, a capacitor of the same value as that of the device under test, we were able to demonstrate that the magnetoelectric device behaves as a voltage source. Furthermore, a simple way to subtract the stray voltage arising from the flow of eddy currents in the measurement set-up, is proposed. This allows the easy and accurate determination of the true magnetoelectric voltage coefficient. A large αΗΜΕ of 8.3 V/cm. Oe was thus obtained for a Terfenol-D/Pt/PZT thin film device, without DC magnetic field nor mechanical resonance.

  4. Mass spectrometry in Earth sciences: the precise and accurate measurement of time.

    PubMed

    Schaltegger, Urs; Wotzlaw, Jörn-Frederik; Ovtcharova, Maria; Chiaradia, Massimo; Spikings, Richard

    2014-01-01

    Precise determinations of the isotopic compositions of a variety of elements is a widely applied tool in Earth sciences. Isotope ratios are used to quantify rates of geological processes that occurred during the previous 4.5 billion years, and also at the present time. An outstanding application is geochronology, which utilizes the production of radiogenic daughter isotopes by the radioactive decay of parent isotopes. Geochronological tools, involving isotopic analysis of selected elements from smallest volumes of minerals by thermal ionization mass spectrometry, provide precise and accurate measurements of time throughout the geological history of our planet over nine orders of magnitude, from the accretion of the proto-planetary disk, to the timing of the last glaciation. This article summarizes the recent efforts of the Isotope Geochemistry, Geochronology and Thermochronology research group at the University of Geneva to advance the U-Pb geochronological tool to achieve unprecedented precision and accuracy, and presents two examples of its application to two significant open questions in Earth sciences: what are the triggers and timescales of volcanic supereruptions, and what were the causes of mass extinctions in the geological past, driven by global climatic and environmental deterioration?

  5. Accurate permittivity measurements for microwave imaging via ultra-wideband removal of spurious reflectors.

    PubMed

    Pelletier, Mathew G; Viera, Joseph A; Wanjura, John; Holt, Greg

    2010-01-01

    The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to derive an estimate of the variability of the hidden material, such internal moisture, thereby alerting personnel to damaging levels of the hidden moisture before material degradation occurs. One impediment to this type of imaging occurs with nearby objects create strong reflections that create destructive and constructive interference, at the receiver, as the material is conveyed past the imaging antenna array. In an effort to remove the influence of the reflectors, such as metal bale ties, research was conducted to develop an algorithm for removal of the influence of the local proximity reflectors from the microwave images. This research effort produced a technique, based upon the use of ultra-wideband signals, for the removal of spurious reflections created by local proximity reflectors. This improvement enables accurate microwave measurements of moisture in such products as cotton bales, as well as other physical properties such as density or material composition. The proposed algorithm was shown to reduce errors by a 4:1 ratio and is an enabling technology for imaging applications in the presence of metal bale ties.

  6. Integration of an intensified charge-coupled device (ICCD) camera for accurate spectroscopic measurements.

    PubMed

    Peláez, Ramón Javier; Mar, Santiago; Aparicio, Juan Antonio; Belmonte, María Teresa

    2012-08-01

    Intensified charge-coupled devices (ICCD) are used in a great variety of spectroscopic applications, some of them requiring high sensitivity and spectral resolution. The setup, configuration, and featuring of these cameras are fundamental issues in order to acquire high quality spectra. In this work a critical assessment of these detectors is performed and the specific configuration, the optical alignment, featuring, and the dark and shot noise are described and analyzed. Spatial response of the detector usually shows a significant lack of spatial homogeneity and a map of interferences may appear in certain ranges of wavelengths, which damages the quality of the recorded spectra. In this work the spectral resolution and the spatial and spectral sensitivity are also studied. The analysis of the dark current reveals the existence of a smooth but clear spatial dependence. As a final conclusion, the spectra registered with the spectrometer equipped with our ICCD camera allow us to explore and measure accurately spectral line shapes emitted by pulsed plasmas in the visible range and particularly in the ultraviolet (UV) range.

  7. Produced water toxicity tests accurately measure the produced water toxicity in marine environments?

    SciTech Connect

    Douglas, W.S.; Veil, J.A.

    1996-10-01

    U.S. Environmental Protection Agency (EPA) Region VI has issued a general permit for offshore oil and gas discharges to the Gulf of Mexico that places numerical limits on whole effluent toxicity (WEI) for produced water. Recently proposed EPA general permits for other produced water discharges in Regions VI and X also include enforceable numerical limits on WET. Clearly, the industry will be conducting extensive produced water WET testing. Unfortunately, the WET test may not accurately measure the toxicity of the chemical constituents of produced water. Rather the mortality of test organisms may be attributable to (1) the high salinity of produced water, which causes salinity shock to the organisms, or (2) an ionic imbalance caused by excesses or deficiencies of one or more of seawater`s essential ions in the test chambers. Both of these effects are likely to be mitigated in actual offshore discharge settings, where the receiving water will be seawater and substantial dilution will be probable. Thus, the additional salinity of produced water will be rapidly assimilated, and the proper marine ionic balance will be quickly restored. Regulatory authorities should be aware of these factors when interpreting WET test results.

  8. An Improved Method for Accurate and Rapid Measurement of Flight Performance in Drosophila

    PubMed Central

    Babcock, Daniel T.; Ganetzky, Barry

    2014-01-01

    Drosophila has proven to be a useful model system for analysis of behavior, including flight. The initial flight tester involved dropping flies into an oil-coated graduated cylinder; landing height provided a measure of flight performance by assessing how far flies will fall before producing enough thrust to make contact with the wall of the cylinder. Here we describe an updated version of the flight tester with four major improvements. First, we added a "drop tube" to ensure that all flies enter the flight cylinder at a similar velocity between trials, eliminating variability between users. Second, we replaced the oil coating with removable plastic sheets coated in Tangle-Trap, an adhesive designed to capture live insects. Third, we use a longer cylinder to enable more accurate discrimination of flight ability. Fourth we use a digital camera and imaging software to automate the scoring of flight performance. These improvements allow for the rapid, quantitative assessment of flight behavior, useful for large datasets and large-scale genetic screens. PMID:24561810

  9. Accurate measurement of transgene copy number in crop plants using droplet digital PCR.

    PubMed

    Collier, Ray; Dasgupta, Kasturi; Xing, Yan-Ping; Hernandez, Bryan Tarape; Shao, Min; Rohozinski, Dominica; Kovak, Emma; Lin, Jeanie; de Oliveira, Maria Luiza P; Stover, Ed; McCue, Kent F; Harmon, Frank G; Blechl, Ann; Thomson, James G; Thilmony, Roger

    2017-02-23

    Genetic transformation is a powerful means for the improvement of crop plants, but requires labor and resource intensive methods. An efficient method for identifying single copy transgene insertion events from a population of independent transgenic lines is desirable. Currently transgene copy number is estimated by either Southern blot hybridization analyses or quantitative polymerase chain reaction (qPCR) experiments. Southern hybridization is a convincing and reliable method, but it also is expensive, time-consuming and often requires a large amount of genomic DNA and radioactively labeled probes. Alternatively, qPCR requires less DNA and is potentially simpler to perform, but its results can lack the accuracy and precision needed to confidently distinguish between one and two copy events in transgenic plants with large genomes. To address this need, we developed a droplet digital PCR (dPCR)-based method for transgene copy number measurement in an array of crops: rice, citrus, potato, maize, tomato, and wheat. The method utilizes specific primers to amplify target transgenes, and endogenous reference genes in a single duplexed reaction containing thousands of droplets. Endpoint amplicon production in the droplets is detected and quantified using sequence-specific fluorescently labeled probes. The results demonstrate that this approach can generate confident copy number measurements in independent transgenic lines in these crop species. This method and the compendium of probes and primers will be a useful resource for the plant research community, enabling the simple and accurate determination of transgene copy number in these six important crop species. This article is protected by copyright. All rights reserved.

  10. Acoustic resolution photoacoustic Doppler flowmetry: practical considerations for obtaining accurate measurements of blood flow

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2014-03-01

    An assessment has been made of various experimental factors affecting the accuracy of flow velocities measured using a pulsed time correlation photoacoustic Doppler technique. In this method, Doppler time shifts are quantified via crosscorrelation of pairs of photoacoustic waveforms generated in moving absorbers using pairs of laser light pulses, and the photoacoustic waves are detected using an ultrasound transducer. The acoustic resolution mode is employed by using the transducer focal width, rather than the large illuminated volume, to define the lateral spatial resolution. This enables penetration depths of several millimetres or centimetres, unlike methods using the optical resolution mode, which limits the maximum penetration depth to approximately 1 mm. In the acoustic resolution mode, it is difficult to detect time shifts in highly concentrated suspensions of flowing absorbers, such as red blood cell suspensions and whole blood, and this challenge supposedly arises because of the lack of spatial heterogeneity. However, by assessing the effect of different absorption coefficients and tube diameters, we offer an alternative explanation relating to light attenuation and parabolic flow. We also demonstrate a new signal processing method that surmounts the previous problem of measurement under-reading. This method is a form of signal range gating and enables mapping of the flow velocity profile across the tube as well as measurement of the average flow velocity. We show that, using our signal processing scheme, it is possible to measure the flow of whole blood using a relatively low frequency detector. This important finding paves the way for application of the technique to measurements of blood flow several centimetres deep in living tissue.

  11. A Robust Method of Vehicle Stability Accurate Measurement Using GPS and INS

    NASA Astrophysics Data System (ADS)

    Miao, Zhibin; Zhang, Hongtian; Zhang, Jinzhu

    2015-12-01

    With the development of the vehicle industry, controlling stability has become more and more important. Techniques of evaluating vehicle stability are in high demand. Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) is a very practical method to get high-precision measurement data. Usually, the Kalman filter is used to fuse the data from GPS and INS. In this paper, a robust method is used to measure vehicle sideslip angle and yaw rate, which are two important parameters for vehicle stability. First, a four-wheel vehicle dynamic model is introduced, based on sideslip angle and yaw rate. Second, a double level Kalman filter is established to fuse the data from Global Positioning System and Inertial Navigation System. Then, this method is simulated on a sample vehicle, using Carsim software to test the sideslip angle and yaw rate. Finally, a real experiment is made to verify the advantage of this approach. The experimental results showed the merits of this method of measurement and estimation, and the approach can meet the design requirements of the vehicle stability controller.

  12. MELIFT - A new device for accurate measurements in a snow rich environment

    NASA Astrophysics Data System (ADS)

    Dorninger, M.

    2012-04-01

    A deep snow pack, remote locations, no external power supply and very low temperatures are often the main ingredients when it comes to the deployment of meteorological stations in mountainous terrain. The accurate position of the sensor related to the snow surface is normally not known. A new device called METLIFT overcomes the problems. WMO recommends a height between 1.2 m and 2 m above ground level for the measurement of air temperature and humidity. The height above ground level is specified to take care of the possible strong vertical temperature and humidity gradients at the lowest layers in the atmosphere. Especially in snow rich and remote locations it may be hardly possible to follow this advice. Therefore most of the meteorological stations in mountainous terrain are situated at mountain tops where strong winds will blow off the snow or in valleys where a daily inspection of the sensors is possible. In other unpopulated mountainous areas, e.g. basins, plateaus, the distance of the sensor to the snow surface is not known or the sensor will be snow-covered. A new device was developed to guarantee the sensor height above surface within the WMO limits in harsh and remote environments. An ultrasonic snow height sensor measures the distance to the snow surface. If it exceeds certain limits due to snow accumulation or snow melt the lift adapts its height accordingly. The prototype of METLIFT has been installed in Lower Austria at an altitude of 1000m. The lift is 6 m high and can pull out for another 4 m. Sensor arms are mounted every meter to allow the connection of additional sensors or to measure a profile of a certain parameter of the lowest 5 m above surface. Sensors can be added easily since cable wiring is provided to each sensor arm. Horizontal winds are measured at 7 m height above surface. METLIFT is independent of external power supply. Three lead gel accumulators recharged by three solar panels provide the energy necessary for the sensors, the data

  13. Towards More Accurate Measurements of the Ionization Energy of Molecular Hydrogen

    NASA Astrophysics Data System (ADS)

    Sprecher, D.; Beyer, M.; Liu, J.; Merkt, F.; Salumbides, E.; Eikema, K. S. E.; Ubachs, W.; Jungen, Ch.

    2013-06-01

    With two electrons and two protons, molecular hydrogen is the simplest molecule displaying all features of a chemical bond. H_2 is therefore a fundamental system for testing molecular quantum mechanics and quantum electrodynamics in molecules. The test can be performed by comparing measured and calculated intervals between different rovibronic states of H_2. Two further quantities that can be used for this test are the dissociation and ionization energies of H_2, and considerable efforts have been invested over more than 80 years to improve the precision and accuracy of experimental and theoretical determination of these two quantities. The current status of the comparison is that the theoretical and experimental values of the ionization and dissociation energies of H_2 agree within the combined uncertainty of 30 MHz (see also). The factors currently limiting the precision of the experimental determination will be discussed and the strategies that are being implemented towards overcoming these limitations will be presented. A long-term goal is to achieve a precision of better than 15 kHz, which is the ultimate limit imposed on the accuracy of the theoretical determination by the current uncertainty of the proton-to-electron mass ratio. E. J. Salumbides, G. D. Dickenson, T. I. Ivanov and W. Ubachs, {Phys. Rev. Lett.} 107 (4), 043005 (2011). K. Piszczatowski, G. Lach, M. Przybytek, J. Komasa, K. Pachuckiand and B. Jeziorski, {J. Chem. Theory Comput.} 5 (11), 3039 (2009). J. Liu, E. J. Salumbides, U. Hollenstein, J. C. J. Koelemeij, K. S. E. Eikema, W. Ubachs and F. Merkt, {J. Chem. Phys.} 130 (17), 174306 (2009). D. Sprecher, Ch. Jungen, W. Ubachs and F. Merkt, {Faraday Discuss.} 150, 51 (2011).

  14. Are portable bladder scanning and real-time ultrasound accurate measures of bladder volume in postnatal women?

    PubMed

    Mathew, S; Horne, A W; Murray, L S; Tydeman, G; McKinley, C A

    2007-08-01

    Real-time ultrasound and portable bladder scanners are commonly used instead of catheterisation to determine bladder volumes in postnatal women but it is not known whether these are accurate. Change in bladder volumes measured by ultrasound and portable scanners were compared with actual voided volume (VV) in 100 postnatal women. The VV was on average 41 ml (CI 29 - 54 ml) higher than that measured by ultrasound, and 33 ml (CI 17 - 48 ml) higher than that measured by portable scanners. Portable scanner volumes were 9 ml (CI -8 - 26 ml) higher than those measured by ultrasound. Neither method is an accurate tool for detecting bladder volume in postnatal women.

  15. A new direct absorption measurement for high precision and accurate measurement of water vapor in the UT/LS

    NASA Astrophysics Data System (ADS)

    Sargent, M. R.; Sayres, D. S.; Smith, J. B.; Anderson, J.

    2011-12-01

    Highly accurate and precise water vapor measurements in the upper troposphere and lower stratosphere are critical to understanding the climate feedbacks of water vapor and clouds in that region. However, the continued disagreement among water vapor measurements (~1 - 2 ppmv) are too large to constrain the role of different hydration and dehydration mechanisms operating in the UT/LS, with model validation dependent upon which dataset is chosen. In response to these issues, we present a new instrument for measurement of water vapor in the UT/LS that was flown during the April 2011 MACPEX mission out of Houston, TX. The dual axis instrument combines the heritage and validated accuracy of the Harvard Lyman-alpha instrument with a newly designed direct IR absorption instrument, the Harvard Herriott Hygrometer (HHH). The Lyman-alpha detection axis has flown aboard NASA's WB-57 and ER2 aircraft since 1994, and provides a requisite link between the new HHH instrument and the long history of Harvard water vapor measurements. The instrument utilizes the highly sensitive Lyman-alpha photo-fragment fluorescence detection method; its accuracy has been demonstrated though rigorous laboratory calibrations and in situ diagnostic procedures. The Harvard Herriott Hygrometer employs a fiber coupled near-IR laser with state-of-the-art electronics to measure water vapor via direct absorption in a spherical Herriott cell of 10 cm length. The instrument demonstrated in-flight precision of 0.1 ppmv (1-sec, 1-sigma) at mixing ratios as low as 5 ppmv with accuracies of 10% based on careful laboratory calibrations and in-flight performance. We present a description of the measurement technique along with our methodology for calibration and details of the measurement uncertainties. The simultaneous utilization of radically different measurement techniques in a single duct in the new Harvard Water Vapor (HWV) instrument allows for the constraint of systematic errors inherent in each technique

  16. Experimental Measurement of In Situ Stress

    NASA Astrophysics Data System (ADS)

    Tibbo, Maria; Milkereit, Bernd; Nasseri, Farzine; Schmitt, Douglas; Young, Paul

    2016-04-01

    The World Stress Map data is determined by stress indicators including earthquake focal mechanisms, in situ measurement in mining, oil and gas boreholes as well as the borehole cores, and geologic data. Unfortunately, these measurements are not only infrequent but sometimes infeasible, and do not provide nearly enough data points with high accuracy to correctly infer stress fields in deep mines around the world. Improvements in stress measurements of Earth's crust is fundamental to several industries such as oil and gas, mining, nuclear waste management, and enhanced geothermal systems. Quantifying the state of stress and the geophysical properties of different rock types is a major complication in geophysical monitoring of deep mines. Most stress measurement techniques involve either the boreholes or their cores, however these measurements usually only give stress along one axis, not the complete stress tensor. The goal of this project is to investigate a new method of acquiring a complete stress tensor of the in situ stress in the Earth's crust. This project is part of a comprehensive, exploration geophysical study in a deep, highly stressed mine located in Sudbury, Ontario, Canada, and focuses on two boreholes located in this mine. These boreholes are approximately 400 m long with NQ diameters and are located at depths of about 1300 - 1600 m and 1700 - 2000 m. Two borehole logging surveys were performed on both boreholes, October 2013 and July 2015, in order to perform a time-lapse analysis of the geophysical changes in the mine. These multi-parameter surveys include caliper, full waveform sonic, televiewer, chargeability (IP), and resistivity. Laboratory experiments have been performed on borehole core samples of varying geologies from each borehole. These experiments have measured the geophysical properties including elastic modulus, bulk modulus, P- and S-wave velocities, and density. The apparatus' used for this project are geophysical imaging cells capable

  17. Accurate method for measurement of pipe wall thickness using a circumferential guided wave generated and detected by a pair of noncontact transducers

    NASA Astrophysics Data System (ADS)

    Nishino, H.; Taniguchi, Y.; Yoshida, K.

    2012-05-01

    A noncontact method of an accurate estimation of a pipe wall thickness using a circumferential (C-) Lamb wave is presented. The C-Lamb waves circling along the circumference of pipes are transmitted and received by the critical angle method using a pair of noncontact air-coupled ultrasonic transducers. For the accurate estimation of a pipe wall thickness, the accurate measurement of the angular wave number that changes minutely owing to the thickness must be achieved. To achieve the accurate measurement, a large number of tone-burst cycles are used so as to superpose the C-Lamb wave on itself along its circumferential orbit. In this setting, the amplitude of the superposed region changes considerably with the angular wave number, from which the wall thickness can be estimated. This paper presents the principle of the method and experimental verifications. As results of the experimental verifications, it was confirmed that the maximum error between the estimates and the theoretical model was less than 10 micrometers.

  18. Theory of bi-molecular association dynamics in 2D for accurate model and experimental parameterization of binding rates

    PubMed Central

    Yogurtcu, Osman N.; Johnson, Margaret E.

    2015-01-01

    The dynamics of association between diffusing and reacting molecular species are routinely quantified using simple rate-equation kinetics that assume both well-mixed concentrations of species and a single rate constant for parameterizing the binding rate. In two-dimensions (2D), however, even when systems are well-mixed, the assumption of a single characteristic rate constant for describing association is not generally accurate, due to the properties of diffusional searching in dimensions d ≤ 2. Establishing rigorous bounds for discriminating between 2D reactive systems that will be accurately described by rate equations with a single rate constant, and those that will not, is critical for both modeling and experimentally parameterizing binding reactions restricted to surfaces such as cellular membranes. We show here that in regimes of intrinsic reaction rate (ka) and diffusion (D) parameters ka/D > 0.05, a single rate constant cannot be fit to the dynamics of concentrations of associating species independently of the initial conditions. Instead, a more sophisticated multi-parametric description than rate-equations is necessary to robustly characterize bimolecular reactions from experiment. Our quantitative bounds derive from our new analysis of 2D rate-behavior predicted from Smoluchowski theory. Using a recently developed single particle reaction-diffusion algorithm we extend here to 2D, we are able to test and validate the predictions of Smoluchowski theory and several other theories of reversible reaction dynamics in 2D for the first time. Finally, our results also mean that simulations of reactive systems in 2D using rate equations must be undertaken with caution when reactions have ka/D > 0.05, regardless of the simulation volume. We introduce here a simple formula for an adaptive concentration dependent rate constant for these chemical kinetics simulations which improves on existing formulas to better capture non-equilibrium reaction dynamics from dilute

  19. Experimental measurement of the Melnikov function

    NASA Astrophysics Data System (ADS)

    Meunier, Patrice; Huck, Peter; Nobili, Clément; Villermaux, Emmanuel

    2015-07-01

    We study the transport properties of a genuine two-dimensional flow with a large mean velocity perturbed periodically in time by means of an original experimental technique. The flow generated by the co-rotation of two cylinders is both stratified with a linear density gradient using salted water and viscous in order to prevent Ekman pumping and centrifugal instabilities. Thus, the mean flow contains a hyperbolic point with a homoclinic streamline, which we perturb periodically by an extra oscillation. A blob of scalar injected close to the stagnation point contracts on the stable manifold and stretches in the unstable direction. The distance between the stable and the unstable manifolds is measured as the distance between the maximum and the minimum of the dye undulating pattern and is recorded as a function of the perturbation frequency. This distance, also called the Melnikov function, presents a maximum when the residence time of a fluid particle in the mean flow is about half a perturbation period. This resonance criterion is recovered with good quantitative agreement by the theoretical prediction of the Melnikov function computed for this flow.

  20. Accurate optical measurement of nuclear polarization in optically pumped ^3He gas

    NASA Astrophysics Data System (ADS)

    Bigelow, N. P.; Nacher, P. J.; Leduc, M.

    1992-12-01

    Large nuclear polarizations M (over 80 %) can now be achieved in gaseous ^3He by optical pumping. The gas is excited by an RF discharge and is oriented using a high power LNA laser which is lamp pumped and tuned to the 2 ^3S-2 ^3P transition at 1.08 μm. In this paper we describe an experiment in which we measure M with high absolute precision. Our method is based on a change as a function of M in the ratio of σ or π polarized light absorbed from a weak probe beam by the 2 ^3S metastable atoms. The probe was delivered by a diode pumped LNA laser and propagated perpendicular to the direction of the magnetization. Simultaneous measurement of M was made by monitoring the degree of circular polarization \\cal{P} of the optical line at 668 nm emitted by the discharge. Our measurements show a linear relationship between M and \\cal{P} for all accessible M values and for a wide range of experimental conditions (sample pressure, magnetic field, RF discharge level, etc.). This provides a second method of measurement of the ^3He nuclear polarization which is simple to operate and is calibrated and is calibrated over a pressure range of 0.15 to 6.5 torr. On peut maintenant produire par pompage optique de fortes polarisations nucléaires M (M supérieure à 80 % dans l' ^3He gazeux. Le gaz est excité par une décharge radiofréquence et orienté à l'aide d'un laser LNA de forte intensité qui est pompé par des lampes et accordé sur la transition 2 ^3S-2 ^3P à 1,08 μm. Dans cet article, nous décrivons une expérience où nous mesurons M avec une grande précision absolue. Notre méthode est fondée sur la variation en fonction de M de l'absorption par les atomes métastables d'un faisceau sonde de faible intensité polarisé linéairement. Nous mesurons le rapport des absorptions pour des polarisations π et σ. Le faisceau sonde est un laser LNA pompé par diode qui se propage perpendiculairement à la direction de l'aimantation. Simultanément, nous mesurons M par le

  1. Noncontact accurate measurement of cardiopulmonary activity using a compact quadrature Doppler radar sensor.

    PubMed

    Hu, Wei; Zhao, Zhangyan; Wang, Yunfeng; Zhang, Haiying; Lin, Fujiang

    2014-03-01

    The designed sensor enables accurate reconstruction of chest-wall movement caused by cardiopulmonary activities, and the algorithm enables estimation of respiration, heartbeat rate, and some indicators of heart rate variability (HRV). In particular, quadrature receiver and arctangent demodulation with calibration are introduced for high linearity representation of chest displacement; 24-bit ADCs with oversampling are adopted for radar baseband acquisition to achieve a high signal resolution; continuous-wavelet filter and ensemble empirical mode decomposition (EEMD) based algorithm are applied for cardio/pulmonary signal recovery and separation so that accurate beat-to-beat interval can be acquired in time domain for HRV analysis. In addition, the wireless sensor is realized and integrated on a printed circuit board compactly. The developed sensor system is successfully tested on both simulated target and human subjects. In simulated target experiments, the baseband signal-to-noise ratio (SNR) is 73.27 dB, high enough for heartbeat detection. The demodulated signal has 0.35% mean squared error, indicating high demodulation linearity. In human subject experiments, the relative error of extracted beat-to-beat intervals ranges from 2.53% to 4.83% compared with electrocardiography (ECG) R-R peak intervals. The sensor provides an accurate analysis for heart rate with the accuracy of 100% for p = 2% and higher than 97% for p = 1%.

  2. Measurement of segregating behaviors in experimental silver fox pedigrees.

    PubMed

    Kukekova, Anna V; Trut, L N; Chase, K; Shepeleva, D V; Vladimirova, A V; Kharlamova, A V; Oskina, I N; Stepika, A; Klebanov, S; Erb, H N; Acland, G M

    2008-03-01

    Strains of silver foxes, selectively bred at the Institute of Cytology and Genetics of the Russian Academy of Sciences, are a well established, novel model for studying the genetic basis of behavior, and the processes involved in canine domestication. Here we describe a method to measure fox behavior as quantitative phenotypes which distinguish populations and resegregate in experimental pedigrees. We defined 50 binary observations that nonredundantly and accurately distinguished behaviors in reference populations and cross-bred pedigrees. Principal-component analysis dissected out the independent elements underlying these behaviors. PC1 accounted for >44% of the total variance in measured traits. This system clearly distinguished tame foxes from aggressive and wildtype foxes. F1 foxes yield intermediate values that extend into the ranges of both the tame and aggressive foxes, while the scores of the backcross generation resegregate. These measures can thus be used for QTL mapping to explore the genetic basis of tame and aggressive behavior in foxes, which should provide new insights into the mechanisms of mammalian behavior and canine domestication.

  3. Experimental measurement-device-independent quantum random-number generation

    NASA Astrophysics Data System (ADS)

    Nie, You-Qi; Guan, Jian-Yu; Zhou, Hongyi; Zhang, Qiang; Ma, Xiongfeng; Zhang, Jun; Pan, Jian-Wei

    2016-12-01

    The randomness from a quantum random-number generator (QRNG) relies on the accurate characterization of its devices. However, device imperfections and inaccurate characterizations can result in wrong entropy estimation and bias in practice, which highly affects the genuine randomness generation and may even induce the disappearance of quantum randomness in an extreme case. Here we experimentally demonstrate a measurement-device-independent (MDI) QRNG based on time-bin encoding to achieve certified quantum randomness even when the measurement devices are uncharacterized and untrusted. The MDI-QRNG is randomly switched between the regular randomness generation mode and a test mode, in which four quantum states are randomly prepared to perform measurement tomography in real time. With a clock rate of 25 MHz, the MDI-QRNG generates a final random bit rate of 5.7 kbps. Such implementation with an all-fiber setup provides an approach to construct a fully integrated MDI-QRNG with trusted but error-prone devices in practice.

  4. Seeking: Accurate Measurement Techniques for Deep-Bone Density and Structure

    NASA Technical Reports Server (NTRS)

    Sibonga, Jean

    2009-01-01

    We are seeking a clinically-useful technology with enough sensitivity to assess the microstructure of "spongy" bone that is found in the marrow cavities of whole bones. However, this technology must be for skeletal sites surrounded by layers of soft tissues, such as the spine and the hip. Soft tissue interferes with conventional imaging and using a more accessible area -- for example, the wrist or the ankle of limbs-- as a proxy for the less accessible skeletal regions, will not be accurate. A non-radioactive technology is strongly preferred.

  5. Novel method for accurate g measurements in electron-spin resonance

    NASA Astrophysics Data System (ADS)

    Stesmans, A.; Van Gorp, G.

    1989-09-01

    In high-accuracy work, electron-spin-resonance (ESR) g values are generally determined by calibrating against the accurately known proton nuclear magnetic resonance (NMR). For that method—based on leakage of microwave energy out of the ESR cavity—a convenient technique is presented to obtain accurate g values without needing conscientious precalibration procedures or cumbersome constructions. As main advantages, the method allows the easy monitoring of the positioning of the ESR and NMR samples while they are mounted as close as physically realizable at all time during their simultaneous resonances. Relative accuracies on g of ≊2×10-6 are easily achieved for ESR signals of peak-to-peak width ΔBpp≲0.3 G. The method has been applied to calibrate the g value of conduction electrons of small Li particles embedded in LiF—a frequently used g marker—resulting in gLiF: Li=2.002 293±0.000 002.

  6. Highly accurate measurements of the spontaneous fission half-life of 240,242Pu

    NASA Astrophysics Data System (ADS)

    Salvador-Castiñeira, P.; Bryś, T.; Eykens, R.; Hambsch, F.-J.; Moens, A.; Oberstedt, S.; Sibbens, G.; Vanleeuw, D.; Vidali, M.; Pretel, C.

    2013-12-01

    Fast spectrum neutron-induced fission cross-section data for transuranic isotopes are of special demand from the nuclear data community. In particular highly accurate data are needed for the new generation IV nuclear applications. The aim is to obtain precise neutron-induced fission cross sections for 240Pu and 242Pu. To do so, accurate data on spontaneous fission half-lives must be available. Also, minimizing uncertainties in the detector efficiency is a key point. We studied both isotopes by means of a twin Frisch-grid ionization chamber with the goal of improving the present data on the neutron-induced fission cross section. For the two plutonium isotopes the high α-particle decay rates pose a particular problem to experiments due to piling-up events in the counting gas. Argon methane and methane were employed as counting gases, the latter showed considerable improvement in signal generation due to its higher drift velocity. The detection efficiency for both samples was determined, and improved spontaneous fission half-lives were obtained with very low statistical uncertainty (0.13% for 240Pu and 0.04% for 242Pu): for 240Pu, T1/2,SF=1.165×1011 yr (1.1%), and for 242Pu, T1/2,SF=6.74×1010 yr (1.3%). Systematic uncertainties are due to sample mass (0.4% for 240Pu and 0.9% for 242Pu) and efficiency (1%).

  7. Skin mechanics measured in vivo using torsion: a new and accurate model more sensitive to age, sex and moisturizing treatment.

    PubMed

    Salter, D C; McArthur, H C; Crosse, J E; Dickens, A D

    1993-10-01

    Summary Measurements of skin mechanics are required to understand better cracking and flaking of the epidermis and loss of 'elasticity'with age in the dermis. Improvements in torsional testing are described here. The resulting data was fitted to algebraic models, the parameters of which can serve both as a concise description of the responses and as a means of relating them to skin structure and physiology. This investigation looks into the suitability of seven such algebraic models. Five of the models examined here appear to be new. Using the commercially available Dia-Stron DTM Torque Meter with our own software, model parameters were studied as indicators of the effects of age and sex in 41 people, and of skin moisturizing treatments in a further 10 people. The two models in the literature were both found to be substantially less accurate and sensitive representations of experimental data than one of the new models proposed here based on the Weibull distribution. This 'WB model'was consistently the one best able to distinguish differences and detect changes which were statistically significant. The WB model appears to be the most powerful and efficient available. Use of this model makes it possible to demonstrate in vivo a statistically significant mechanical difference between male and pre-menopausal female skin using only one parameter (p= 0.0163, with 18 males and 19 females) and to demonstrate a statistically significant mechanical difference between successive decades of age in female skin using only one parameter (p= 0.0124, n= 24). The two parameters of the model most sensitive to skin structure, function and treatment have been combined to form the axes of a 'Skin condition chart'. Any person can be located on this chart at a point indicating their overall skin condition in mechanical terms and any changes in that condition can be clearly demonstrated by movement across the plot.

  8. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... royalty: (1) If the meter measures electricity, it must have an accuracy of ±0.25% or better of reading... meter measures water flowing at more than 500,000 lbs/hr on a monthly basis, it must have an accuracy reading of ±2 percent or better; (5) If the meter measures water flowing at 500,000 lbs/hr or less on...

  9. Lightdrum—Portable Light Stage for Accurate BTF Measurement on Site

    PubMed Central

    Havran, Vlastimil; Hošek, Jan; Němcová, Šárka; Čáp, Jiří; Bittner, Jiří

    2017-01-01

    We propose a miniaturised light stage for measuring the bidirectional reflectance distribution function (BRDF) and the bidirectional texture function (BTF) of surfaces on site in real world application scenarios. The main principle of our lightweight BTF acquisition gantry is a compact hemispherical skeleton with cameras along the meridian and with light emitting diode (LED) modules shining light onto a sample surface. The proposed device is portable and achieves a high speed of measurement while maintaining high degree of accuracy. While the positions of the LEDs are fixed on the hemisphere, the cameras allow us to cover the range of the zenith angle from 0∘ to 75∘ and by rotating the cameras along the axis of the hemisphere we can cover all possible camera directions. This allows us to take measurements with almost the same quality as existing stationary BTF gantries. Two degrees of freedom can be set arbitrarily for measurements and the other two degrees of freedom are fixed, which provides a tradeoff between accuracy of measurements and practical applicability. Assuming that a measured sample is locally flat and spatially accessible, we can set the correct perpendicular direction against the measured sample by means of an auto-collimator prior to measuring. Further, we have designed and used a marker sticker method to allow for the easy rectification and alignment of acquired images during data processing. We show the results of our approach by images rendered for 36 measured material samples. PMID:28241466

  10. A More Accurate Measurement of the {sup 28}Si Lattice Parameter

    SciTech Connect

    Massa, E. Sasso, C. P.; Mana, G.; Palmisano, C.

    2015-09-15

    In 2011, a discrepancy between the values of the Planck constant measured by counting Si atoms and by comparing mechanical and electrical powers prompted a review, among others, of the measurement of the spacing of {sup 28}Si (220) lattice planes, either to confirm the measured value and its uncertainty or to identify errors. This exercise confirmed the result of the previous measurement and yields the additional value d{sub 220} = 192 014 711.98(34) am having a reduced uncertainty.

  11. Metrology target design simulations for accurate and robust scatterometry overlay measurements

    NASA Astrophysics Data System (ADS)

    Ben-Dov, Guy; Tarshish-Shapir, Inna; Gready, David; Ghinovker, Mark; Adel, Mike; Herzel, Eitan; Oh, Soonho; Choi, DongSub; Han, Sang Hyun; El Kodadi, Mohamed; Hwang, Chan; Lee, Jeongjin; Lee, Seung Yoon; Lee, Kuntack

    2016-03-01

    Overlay metrology target design is an essential step prior to performing overlay measurements. This step is done through the optimization of target parameters for a given process stack. A simulation tool is therefore used to improve measurement performances. This work shows how our Metrology Target Design (MTD) simulator helps significantly in the target design process. We show the role of film and Optical CD measurements in improving significantly the fidelity of the simulations. We demonstrate that for various target design parameters we are capable of predicting measured performance metrics by simulations and correctly rank various designs performances.

  12. Establishing traceability of photometric absorbance values for accurate measurements of the haemoglobin concentration in blood

    NASA Astrophysics Data System (ADS)

    Witt, K.; Wolf, H. U.; Heuck, C.; Kammel, M.; Kummrow, A.; Neukammer, J.

    2013-10-01

    Haemoglobin concentration in blood is one of the most frequently measured analytes in laboratory medicine. Reference and routine methods for the determination of the haemoglobin concentration in blood are based on the conversion of haeme, haemoglobin and haemiglobin species into uniform end products. The total haemoglobin concentration in blood is measured using the absorbance of the reaction products. Traceable absorbance measurement values on the highest metrological level are a prerequisite for the calibration and evaluation of procedures with respect to their suitability for routine measurements and their potential as reference measurement procedures. For this purpose, we describe a procedure to establish traceability of spectral absorbance measurements for the haemiglobincyanide (HiCN) method and for the alkaline haematin detergent (AHD) method. The latter is characterized by a higher stability of the reaction product. In addition, the toxic hazard of cyanide, which binds to the iron ion of the haem group and thus inhibits the oxygen transport, is avoided. Traceability is established at different wavelengths by applying total least-squares analysis to derive the conventional quantity values for the absorbance from the measured values. Extrapolation and interpolation are applied to get access to the spectral regions required to characterize the Q-absorption bands of the HiCN and AHD methods, respectively. For absorbance values between 0.3 and 1.8, the contributions of absorbance measurements to the total expanded uncertainties (95% level of confidence) of absorbance measurements range from 1% to 0.4%.

  13. Lightdrum-Portable Light Stage for Accurate BTF Measurement on Site.

    PubMed

    Havran, Vlastimil; Hošek, Jan; Němcová, Šárka; Čáp, Jiří; Bittner, Jiří

    2017-02-23

    We propose a miniaturised light stage for measuring the bidirectional reflectance distribution function (BRDF) and the bidirectional texture function (BTF) of surfaces on site in real world application scenarios. The main principle of our lightweight BTF acquisition gantry is a compact hemispherical skeleton with cameras along the meridian and with light emitting diode (LED) modules shining light onto a sample surface. The proposed device is portable and achieves a high speed of measurement while maintaining high degree of accuracy. While the positions of the LEDs are fixed on the hemisphere, the cameras allow us to cover the range of the zenith angle from 0 ∘ to 75 ∘ and by rotating the cameras along the axis of the hemisphere we can cover all possible camera directions. This allows us to take measurements with almost the same quality as existing stationary BTF gantries. Two degrees of freedom can be set arbitrarily for measurements and the other two degrees of freedom are fixed, which provides a tradeoff between accuracy of measurements and practical applicability. Assuming that a measured sample is locally flat and spatially accessible, we can set the correct perpendicular direction against the measured sample by means of an auto-collimator prior to measuring. Further, we have designed and used a marker sticker method to allow for the easy rectification and alignment of acquired images during data processing. We show the results of our approach by images rendered for 36 measured material samples.

  14. Convenient, Rapid and Accurate Measurement of SVOC Emission Characteristics in Experimental Chambers

    PubMed Central

    Liu, Cong; Liu, Zhe; Little, John C.; Zhang, Yinping

    2013-01-01

    Chamber tests are usually used to determine the source characteristics of semi-volatile organic compounds (SVOCs) which are critical to quantify indoor exposure to SVOCs. In contrast to volatile organic compounds (VOCs), the sorption effect of SVOCs to chamber surfaces usually needs to be considered due to the much higher surface/air partition coefficients, resulting in a long time to reach steady state, frequently on the order of months, and complicating the mathematical analysis of the resulting data. A chamber test is also complicated if the material-phase concentration is not constant. This study shows how to design a chamber to overcome these limitations. A dimensionless mass transfer analysis is used to specify conditions for (1) neglecting the SVOC sorption effect to chamber surfaces, (2) neglecting the convective mass transfer resistance at sorption surfaces if the sorption effect cannot be neglected, and (3) regarding the material-phase concentration in the source as constant. Several practical and quantifiable ways to improve chamber design are proposed. The approach is illustrated by analyzing available data from three different chambers in terms of the accuracy with which the model parameters can be determined and the time needed to conduct the chamber test. The results should greatly facilitate the design of chambers to characterize SVOC emissions and the resulting exposure. PMID:24015246

  15. Accurate measurements of fission-fragment yields in 234,235,236,238U(γ,f) with the SOFIA set-up

    NASA Astrophysics Data System (ADS)

    Chatillon, A.; Taïeb, J.; Martin, J.-F.; Pellereau, E.; Boutoux, G.; Gorbinet, T.; Grente, L.; Bélier, G.; Laurent, B.; Alvarez-Pol, H.; Ayyad, Y.; Benlliure, J.; Caamaño, M.; Audouin, L.; Casarejos, E.; Cortina-Gil, D.; Farget, F.; Fernández-Domínguez, B.; Heinz, A.; Jurado, B.; Kelić-Heil, A.; Kurz, N.; Lindberg, S.; Löher, B.; Nociforo, C.; Paradela, C.; Pietri, S.; Ramos, D.; Rodriguez-Sanchez, J.-L.; Rodrìguez-Tajes, C.; Rossi, D.; Schmidt, K.-H.; Simon, H.; Tassan-Got, L.; Törnqvist, H.; Vargas, J.; Voss, B.; Weick, H.; Yan, Y.

    2016-03-01

    SOFIA (Studies On Fission with Aladin) is a new experimental set-up dedicated to accurate measurement of fission-fragments isotopic yields. It is located at GSI, the only place to use inverse kinematics at relativistic energies in order to study the (γ,f) electromagnetic-induced fission. The SOFIA set-up is a large-acceptance magnetic spectrometer, which allows to fully identify both fission fragments in coincidence on the whole fission-fragment range. This paper will report on fission yields obtained in 234,235,236,238U(γ,f) reactions.

  16. Archimedes Revisited: A Faster, Better, Cheaper Method of Accurately Measuring the Volume of Small Objects

    ERIC Educational Resources Information Center

    Hughes, Stephen W.

    2005-01-01

    A little-known method of measuring the volume of small objects based on Archimedes' principle is described, which involves suspending an object in a water-filled container placed on electronic scales. The suspension technique is a variation on the hydrostatic weighing technique used for measuring volume. The suspension method was compared with two…

  17. Experimental measurements on a single sweeping jet

    NASA Astrophysics Data System (ADS)

    Hirsch, Damian; Graff, Emilio; Gharib, Morteza

    2014-11-01

    ``Sweeping jets'' proved their effectiveness as Active Flow Control (AFC) actuators in improving the performance of vertical tails of generic and full-scale models. To gain further knowledge about the fundamental flow physics, the jets were investigated experimentally. The influence of a single jet on its surroundings was studied, especially the entrainment region. The results were compared to previous experiments to study the difference between a single isolated jet and multiple jets mounted on a vertical tail. Supported by the Boeing Company.

  18. Technical Note: PRESAGE three-dimensional dosimetry accurately measures Gamma Knife output factors

    PubMed Central

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-01-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and two-dimensional detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ± 0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors. PMID:25368961

  19. [Research on accurate measurement of oxygen content in coal using laser-induced breakdown spectroscopy in air environment].

    PubMed

    Yin, Wang-bao; Zhang, Lei; Wang, Le; Dong, Lei; Ma, Wei-guang; Jia, Suo-tang

    2012-01-01

    A technique about accurate measurement of oxygen content in coal in air environment using laser-induced breakdown spectroscopy (LIBS) is introduced in the present paper. Coal samples were excited by the laser, and plasma spectra were obtained. Combining internal standard method, temperature correction method and multi-line methods, the oxygen content of coal samples was precisely measured. The measurement precision is not less than 1.37% for oxygen content in coal analysis, so is satisfied for the requirement of coal-fired power plants in coal analysis. This method can be used in surveying, environmental protection, medicine, materials, archaeological and food safety, biochemical and metallurgy application.

  20. Novel methodology for accurate resolution of fluid signatures from multi-dimensional NMR well-logging measurements.

    PubMed

    Anand, Vivek

    2017-03-01

    A novel methodology for accurate fluid characterization from multi-dimensional nuclear magnetic resonance (NMR) well-logging measurements is introduced. This methodology overcomes a fundamental challenge of poor resolution of features in multi-dimensional NMR distributions due to low signal-to-noise ratio (SNR) of well-logging measurements. Based on an unsupervised machine-learning concept of blind source separation, the methodology resolves fluid responses from simultaneous analysis of large quantities of well-logging data. The multi-dimensional NMR distributions from a well log are arranged in a database matrix that is expressed as the product of two non-negative matrices. The first matrix contains the unique fluid signatures, and the second matrix contains the relative contributions of the signatures for each measurement sample. No a priori information or subjective assumptions about the underlying features in the data are required. Furthermore, the dimensionality of the data is reduced by several orders of magnitude, which greatly simplifies the visualization and interpretation of the fluid signatures. Compared to traditional methods of NMR fluid characterization which only use the information content of a single measurement, the new methodology uses the orders-of-magnitude higher information content of the entire well log. Simulations show that the methodology can resolve accurate fluid responses in challenging SNR conditions. The application of the methodology to well-logging data from a heavy oil reservoir shows that individual fluid signatures of heavy oil, water associated with clays and water in interstitial pores can be accurately obtained.

  1. Novel methodology for accurate resolution of fluid signatures from multi-dimensional NMR well-logging measurements

    NASA Astrophysics Data System (ADS)

    Anand, Vivek

    2017-03-01

    A novel methodology for accurate fluid characterization from multi-dimensional nuclear magnetic resonance (NMR) well-logging measurements is introduced. This methodology overcomes a fundamental challenge of poor resolution of features in multi-dimensional NMR distributions due to low signal-to-noise ratio (SNR) of well-logging measurements. Based on an unsupervised machine-learning concept of blind source separation, the methodology resolves fluid responses from simultaneous analysis of large quantities of well-logging data. The multi-dimensional NMR distributions from a well log are arranged in a database matrix that is expressed as the product of two non-negative matrices. The first matrix contains the unique fluid signatures, and the second matrix contains the relative contributions of the signatures for each measurement sample. No a priori information or subjective assumptions about the underlying features in the data are required. Furthermore, the dimensionality of the data is reduced by several orders of magnitude, which greatly simplifies the visualization and interpretation of the fluid signatures. Compared to traditional methods of NMR fluid characterization which only use the information content of a single measurement, the new methodology uses the orders-of-magnitude higher information content of the entire well log. Simulations show that the methodology can resolve accurate fluid responses in challenging SNR conditions. The application of the methodology to well-logging data from a heavy oil reservoir shows that individual fluid signatures of heavy oil, water associated with clays and water in interstitial pores can be accurately obtained.

  2. Accurate evaluation of viscoelasticity of radial artery wall during flow-mediated dilation in ultrasound measurement

    NASA Astrophysics Data System (ADS)

    Sakai, Yasumasa; Taki, Hirofumi; Kanai, Hiroshi

    2016-07-01

    In our previous study, the viscoelasticity of the radial artery wall was estimated to diagnose endothelial dysfunction using a high-frequency (22 MHz) ultrasound device. In the present study, we employed a commercial ultrasound device (7.5 MHz) and estimated the viscoelasticity using arterial pressure and diameter, both of which were measured at the same position. In a phantom experiment, the proposed method successfully estimated the elasticity and viscosity of the phantom with errors of 1.8 and 30.3%, respectively. In an in vivo measurement, the transient change in the viscoelasticity was measured for three healthy subjects during flow-mediated dilation (FMD). The proposed method revealed the softening of the arterial wall originating from the FMD reaction within 100 s after avascularization. These results indicate the high performance of the proposed method in evaluating vascular endothelial function just after avascularization, where the function is difficult to be estimated by a conventional FMD measurement.

  3. Accurate VUV Laboratory Measurements of Fe III Transitions for Astrophysical Applications

    NASA Technical Reports Server (NTRS)

    Blackwell-Whitehead, R. J.; Pickering, J. C.; Smillie, D.; Nave, G.; Szabo, C. I.; Smith, Peter L.; Nielsen, K. E.; Peters, G.

    2006-01-01

    We report preliminary measurements of Fe III spectra in the 1150 to 2500 A wavelength interval. Spectra have been recorded with an iron-neon Penning discharge lamp (PDL) between 1600 and 2500 A at Imperial College (IC) using high resolution Fourier (FT) transform spectroscopy. These FT spectrometer measurements were extended beyond 1600 A to 1150 A using high-resolution grating spectroscopy at the National Institute of Standards and Technology (NIST). These recorded spectra represent the first radiometrically calibrated measurements of a doubly-ionized iron-group element spectrum combining the techniques of vacuum ultraviolet FT and grating spectroscopy. The spectral range of the new laboratory measurements corresponds to recent HST/STIS observations of sharp-lined B stars and of Eta Carinae. The new improved atomic data can be applied to abundance studies and diagnostics of astrophysical plasmas.

  4. Accurate Ultrasonic Measurement of Surface Profile Using Phase Shift of Echo and Inverse Filtering

    NASA Astrophysics Data System (ADS)

    Arihara, Chihiro; Hasegawa, Hideyuki; Kanai, Hiroshi

    2006-05-01

    Atherosclerosis is the main cause of circulatory diseases such as myocardial infarction and cerebral infarction, and it is very important to diagnose atherosclerosis in its early stage. In the early stage of atherosclerosis, the luminal surface of an arterial wall becomes rough because of the injury of the endothelium [R. Ross: New Engl. J. Med. 340 (2004) 115]. Conventional ultrasonic diagnostic equipments cannot detect such roughness on the order of micrometer because of their low resolution of approximately 0.1 mm. In this study, for the accurate detection of surface roughness, an ultrasonic beam was scanned in the direction that is parallel to the surface of an object. When there is a gap on the surface, the phase of the echo from the surface changes because the distance between the probe and the surface changes during the scanning. Therefore, surface roughness can be assessed by estimating the phase shift of echoes obtained during the beam scanning. Furthermore, lateral resolution, which is deteriorated by a finite diameter of the ultrasound beam, was improved by an inverse filter. By using the proposed method, the surface profile of a phantom, which had surface roughness on the micrometer order, was detected, and the estimated surface profiles became more precise by applying the inverse filter.

  5. Evaluation of accurate mass and relative isotopic abundance measurements in the LTQ-orbitrap mass spectrometer for further metabolomics database building.

    PubMed

    Xu, Ying; Heilier, Jean-François; Madalinski, Geoffrey; Genin, Eric; Ezan, Eric; Tabet, Jean-Claude; Junot, Christophe

    2010-07-01

    Recently, high-resolution mass spectrometry has been largely employed for compound identification, thanks to accurate mass measurements. As additional information, relative isotope abundance (RIA) is often needed to reduce the number of candidates prior to tandem MS(n). Here, we report on the evaluation of the LTQ-Orbitrap, in terms of accurate mass and RIA measurements for building further metabolomics spectral databases. Accurate mass measurements were achieved in the ppm range, using external calibration within 24 h, and remained at <5 ppm over a one-week period. The experimental relative abundances of (M+1) isotopic ions were evaluated in different data sets. First of all, 137 solutions of commercial compounds were analyzed by flow injection analysis in both the positive and negative ion modes. It was found that the ion abundance was the main factor impacting the accuracy of RIA measurements. It was possible to define some intensity thresholds above which errors were systematically <20% of their theoretical values. The same type of results were obtained with analyses from two biological media. Otherwise, no significant effect of ion transmission between the LTQ ion trap and the Orbitrap analyzer on RIA measurement errors was found, whereas the reliability of RIA measurements was dramatically improved by reducing the mass detection window. It was also observed that the signal integration method had a significant impact on RIA measurement errors, with the most-reliable results being obtained with peak height integrations. Finally, automatic integrations using the data preprocessing software XCMS and MZmine gave results similar to those obtained by manual integration, suggesting that it is relevant to use the RIA information in automatic elemental composition determination software from metabolomic peak tables.

  6. Instrumentation for the accurate measurement of phase and amplitude in optical tomography

    NASA Astrophysics Data System (ADS)

    Nissilä, Ilkka; Kotilahti, Kalle; Fallström, Kim; Katila, Toivo

    2002-09-01

    A single-channel prototype for a frequency-domain optical tomography system is presented. The two main goals in the design of the system were the measurement of phase with minimal systematic errors and a high enough signal-to-noise ratio to detect the small changes in the absorption of brain tissue during brain activity. Although the system inherently is an imaging system, the aspects of the system that relate to multichannel operation will be published separately, as this part of the system is not yet finished. The instrument is described in detail, including the radio-frequency system, the light detection system, and the light source. Factors that affect the accuracy of the measured phase include phase drift, radio-frequency coupling between the source and detector electronics, phase-amplitude cross talk, and others. To increase the range of intensities that can be measured, the gain of the detector is adjusted while keeping the mean anode current small compared with the quiescent current through the voltage bleeder of the photomultiplier tube so that cross talk is avoided. The calibration of the measurements is considered, and the data measured on a phantom are compared with a time-resolved instrument as well as with a finite-element forward model. The instrument allows the measurement of phase to an accuracy of 0.5° between 80 fW and 80 nW at a modulation frequency of 100 MHz, giving a dynamic range of 1:106. With a time constant of 0.3 s, phase noise is 0.5° at 1 pW and decreases to 0.06° in a typical activation measurement at 3 cm separation between the optodes. Amplitude noise is 0.8% at 1 pW and 0.1% at 3 cm separation.

  7. Three dimensional accurate morphology measurements of polystyrene standard particles on silicon substrate by electron tomography.

    PubMed

    Hayashida, Misa; Kumagai, Kazuhiro; Malac, Marek

    2015-12-01

    Polystyrene latex (PSL) nanoparticle (NP) sample is one of the most widely used standard materials. It is used for calibration of particle counters and particle size measurement tools. It has been reported that the measured NP sizes by various methods, such as Differential Mobility Analysis, dynamic light scattering (DLS), optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM), differ from each other. Deformation of PSL NPs on mica substrate has been reported in AFM measurements: the lateral width of PSL NPs is smaller than their vertical height. To provide a reliable calibration standard, the deformation must be measured by a method that can reliably visualize the entire three dimensional (3D) shape of the PSL NPs. Here we present a method for detailed measurement of PSL NP 3D shape by means of electron tomography in a transmission electron microscope. The observed shape of the PSL NPs with 100 nm and 50 nm diameter were not spherical, but squished in direction perpendicular to the support substrate by about 7.4% and 12.1%, respectively. The high difference in surface energy of the PSL NPs and that of substrate together with their low Young modulus appear to explain the squishing of the NPs without presence of water film.

  8. Accurate GPS measurement of the location and orientation of a floating platform. [for sea floor geodesy

    NASA Technical Reports Server (NTRS)

    Purcell, G. H., Jr.; Young, L. E.; Wolf, S. K.; Meehan, T. K.; Duncan, C. B.; Fisher, S. S.; Spiess, F. N.; Austin, G.; Boegeman, D. E.; Lowenstein, C. D.

    1990-01-01

    This article describes the design and initial tests of the GPS portion of a system for making seafloor geodesy measurements. In the planned system, GPS antennas on a floating platform will be used to measure the location of an acoustic transducer, attached below the platform, which interrogates an array of transponders on the seafloor. Since the GPS antennas are necessarily some distance above the transducer, a short-baseline GPS interferometer consisting of three antennas is used to measure the platform's orientation. A preliminary test of several crucial elements of the system was performed. The test involved a fixed antenna on the pier and a second antenna floating on a buoy about 80 m away. GPS measurements of the vertical component of this baseline, analyzed independently by two groups using different software, agree with each other and with an independent measurement within a centimeter. The first test of an integrated GPS/acoustic system took place in the Santa Cruz Basin off the coast of southern California in May 1990. In this test a much larger buoy, designed and built at SIO, was equipped with three GPS antennas and an acoustic transducer that interrogated a transponder on the ocean floor. Preliminary analysis indicates that the horizontal position of the transponder can be determined with a precision of about a centimeter.

  9. Accurate GPS measurement of the location and orientation of a floating platform

    NASA Astrophysics Data System (ADS)

    Purcell, G. H., Jr.; Young, L. E.; Wolf, S. K.; Meehan, T. K.; Duncan, C. B.; Fisher, S. S.; Spiess, F. N.; Austin, G.; Boegeman, D. E.; Lowenstein, C. D.

    This article describes the design and initial tests of the GPS portion of a system for making seafloor geodesy measurements. In the planned system, GPS antennas on a floating platform will be used to measure the location of an acoustic transducer, attached below the platform, which interrogates an array of transponders on the seafloor. Since the GPS antennas are necessarily some distance above the transducer, a short-baseline GPS interferometer consisting of three antennas is used to measure the platform's orientation. A preliminary test of several crucial elements of the system was performed. The test involved a fixed antenna on the pier and a second antenna floating on a buoy about 80 m away. GPS measurements of the vertical component of this baseline, analyzed independently by two groups using different software, agree with each other and with an independent measurement within a centimeter. The first test of an integrated GPS/acoustic system took place in the Santa Cruz Basin off the coast of southern California in May 1990. In this test a much larger buoy, designed and built at SIO, was equipped with three GPS antennas and an acoustic transducer that interrogated a transponder on the ocean floor. Preliminary analysis indicates that the horizontal position of the transponder can be determined with a precision of about a centimeter.

  10. Are tidal volume measurements in neonatal pressure-controlled ventilation accurate?

    PubMed

    Chow, Lily C; Vanderhal, Andre; Raber, Jorge; Sola, Augusto

    2002-09-01

    Bedside pulmonary mechanics monitors (PMM) have become useful in ventilatory management in neonates. These monitors are used more frequently due to recent improvements in data-processing capabilities. PMM devices are often part of the ventilator or are separate units. The accuracy and reliability of these systems have not been carefully evaluated. We compared a single ventilatory parameter, tidal volume (V(t)), as measured by several systems. We looked at two freestanding PMMs: the Ventrak Respiratory Monitoring System (Novametrix, Wallingford, CT) and the Bicore CP-100 Neonatal Pulmonary Monitor (Allied Health Care Products, Riverside, CA), and three ventilators with built-in PMM: the VIP Bird Ventilator (Bird Products Corp., Palm Springs, CA), Siemens Servo 300A (Siemens-Elema AB, Solna, Sweden), and Drager Babylog 8000 (Drager, Inc., Chantilly, VA). A calibrated syringe (Hans Rudolph, Inc., Kansas City, MO) was used to deliver tidal volumes of 4, 10, and 20 mL to each ventilator system coupled with a freestanding PMM. After achieving steady state, six consecutive V(t) readings were taken simultaneously from the freestanding PMM and each ventilator. In a second portion of the bench study, we used pressure-control ventilation and measured exhaled tidal volume (V(te)) while ventilating a Bear Test Lung with the same three ventilators. We adjusted peak inspiratory pressure (PIP) under controlled conditions to achieve the three different targeted tidal volumes on the paired freestanding PMM. Again, six V(te) measurements were recorded for each tidal volume. Means and standard deviations were calculated.The percentage difference in measurement of V(t) delivered by calibrated syringe varied greatly, with the greatest discrepancy seen in the smallest tidal volumes, by up to 28%. In pressure control mode, V(te) as measured by the Siemens was significantly overestimated by 20-95%, with the biggest discrepancy at the smallest V(te), particularly when paired with the Bicore

  11. A flux monitoring method for easy and accurate flow rate measurement in pressure-driven flows.

    PubMed

    Siria, Alessandro; Biance, Anne-Laure; Ybert, Christophe; Bocquet, Lydéric

    2012-03-07

    We propose a low-cost and versatile method to measure flow rate in microfluidic channels under pressure-driven flows, thereby providing a simple characterization of the hydrodynamic permeability of the system. The technique is inspired by the current monitoring method usually employed to characterize electro-osmotic flows, and makes use of the measurement of the time-dependent electric resistance inside the channel associated with a moving salt front. We have successfully tested the method in a micrometer-size channel, as well as in a complex microfluidic channel with a varying cross-section, demonstrating its ability in detecting internal shape variations.

  12. Experimental Fracture Measurements of Functionally Graded Materials

    NASA Astrophysics Data System (ADS)

    Carpenter, Ray Douglas

    The primary objective of this research was to extend established fracture toughness testing methods to a new class of engineering materials known as functionally graded materials (FGMs). Secondary goals were to compare experimental results to those predicted by finite element models and to provide fracture test results as feedback toward optimizing processing parameters for the in-house synthesis of a MoSi2/SiC FGM. Preliminary experiments were performed on commercially pure (CP) Ti and uniform axial tensile tests resulted in mechanical property data including yield strength, 268 MPa, ultimate tensile strength, 470 MPa and Young's modulus, 110 GPa. Results from 3-point bending fracture experiments on CP Ti demonstrated rising R-curve behavior and experimentally determined JQ fracture toughness values ranged between 153 N/mm and 254 N/mm. Similar experimental protocols were used for fracture experiments on a 7- layered Ti/TiB FGM material obtained from Cercom in Vista, California. A novel technique for pre-cracking in reverse 4-point bending was developed for this ductile/brittle FGM material. Fracture test results exhibited rising R-curve behavior and estimated JQ fracture toughness values ranged from 0.49 N/mm to 2.63 N/mm. A 5- layered MoSi2/SiC FGM was synthesized using spark plasma sintering (SPS). Samples of this material were fracture tested and the results again exhibited a rising R-curve with KIC fracture toughness values ranging from 2.7 MPa-m1/2 to 6.0 MPa-m1/2. Finite Element Models predicted rising R-curve behavior for both of the FGM materials tested. Model results were in close agreement for the brittle MoSi2/SiC FGM. For the relatively more ductile Ti/TiB material, results were in close agreement at short crack lengths but diverged at longer crack lengths because the models accounted for fracture toughening mechanisms at the crack tip but not those acting in the crack wake.

  13. The accurate measurement of fear memory in Pavlovian conditioning: Resolving the baseline issue.

    PubMed

    Jacobs, Nathan S; Cushman, Jesse D; Fanselow, Michael S

    2010-07-15

    Fear conditioning has become an indispensable behavioral task in an increasingly vast array of research disciplines. Yet one unresolved issue is how conditional fear to an explicit cue interacts with and is potentially confounded by fear prior to tone presentation, referred to as baseline fear. After tone-shock pairings, we experimentally manipulated baseline fear by presenting unpaired shocks in the testing chamber and then analyzed the accuracy of common methods for reporting tone fear. Our findings indicate that baseline fear and tone fear tend to interact, where freezing to the tone increases as baseline fear increases. However, the form of interaction is not linear across all conditions and none of the commonly used reporting methods were consistently able to eliminate the confounding effects of baseline fear. We propose a methodological solution in which baseline fear is reduced to very low levels by first extinguishing fear to the training context and then pre-exposing to the testing context.

  14. Development and calibration of an accurate 6-degree-of-freedom measurement system with total station

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Lin, Jiarui; Yang, Linghui; Zhu, Jigui

    2016-12-01

    To meet the demand of high-accuracy, long-range and portable use in large-scale metrology for pose measurement, this paper develops a 6-degree-of-freedom (6-DOF) measurement system based on total station by utilizing its advantages of long range and relative high accuracy. The cooperative target sensor, which is mainly composed of a pinhole prism, an industrial lens, a camera and a biaxial inclinometer, is designed to be portable in use. Subsequently, a precise mathematical model is proposed from the input variables observed by total station, imaging system and inclinometer to the output six pose variables. The model must be calibrated in two levels: the intrinsic parameters of imaging system, and the rotation matrix between coordinate systems of the camera and the inclinometer. Then corresponding approaches are presented. For the first level, we introduce a precise two-axis rotary table as a calibration reference. And for the second level, we propose a calibration method by varying the pose of a rigid body with the target sensor and a reference prism on it. Finally, through simulations and various experiments, the feasibilities of the measurement model and calibration methods are validated, and the measurement accuracy of the system is evaluated.

  15. An affordable and accurate conductivity probe for density measurements in stratified flows

    NASA Astrophysics Data System (ADS)

    Carminati, Marco; Luzzatto-Fegiz, Paolo

    2015-11-01

    In stratified flow experiments, conductivity (combined with temperature) is often used to measure density. The probes typically used can provide very fine spatial scales, but can be fragile, expensive to replace, and sensitive to environmental noise. A complementary instrument, comprising a low-cost conductivity probe, would prove valuable in a wide range of applications where resolving extremely small spatial scales is not needed. We propose using micro-USB cables as the actual conductivity sensors. By removing the metallic shield from a micro-B connector, 5 gold-plated microelectrodes are exposed and available for 4-wire measurements. These have a cell constant ~550m-1, an intrinsic thermal noise of at most 30pA/Hz1/2, as well as sub-millisecond time response, making them highly suitable for many stratified flow measurements. In addition, we present the design of a custom electronic board (Arduino-based and Matlab-controlled) for simultaneous acquisition from 4 sensors, with resolution (in conductivity, and resulting density) exceeding the performance of typical existing probes. We illustrate the use of our conductivity-measuring system through stratified flow experiments, and describe plans to release simple instructions to construct our complete system for around 200.

  16. EEMD based pitch evaluation method for accurate grating measurement by AFM

    NASA Astrophysics Data System (ADS)

    Li, Changsheng; Yang, Shuming; Wang, Chenying; Jiang, Zhuangde

    2016-09-01

    The pitch measurement and AFM calibration precision are significantly influenced by the grating pitch evaluation method. This paper presents the ensemble empirical mode decomposition (EEMD) based pitch evaluation method to relieve the accuracy deterioration caused by high and low frequency components of scanning profile during pitch evaluation. The simulation analysis shows that the application of EEMD can improve the pitch accuracy of the FFT-FT algorithm. The pitch error is small when the iteration number of the FFT-FT algorithms was 8. The AFM measurement of the 500 nm-pitch one-dimensional grating shows that the EEMD based pitch evaluation method could improve the pitch precision, especially the grating line position precision, and greatly expand the applicability of the gravity center algorithm when particles and impression marks were distributed on the sample surface. The measurement indicates that the nonlinearity was stable, and the nonlinearity of x axis and forward scanning was much smaller than their counterpart. Finally, a detailed pitch measurement uncertainty evaluation model suitable for commercial AFMs was demonstrated and a pitch uncertainty in the sub-nanometer range was achieved. The pitch uncertainty was reduced about 10% by EEMD.

  17. High- and low-pressure pneumotachometers measure respiration rates accurately in adverse environments

    NASA Technical Reports Server (NTRS)

    Fagot, R. J.; Mc Donald, R. T.; Roman, J. A.

    1968-01-01

    Respiration-rate transducers in the form of pneumotachometers measure respiration rates of pilots operating high performance research aircraft. In each low pressure or high pressure oxygen system a sensor is placed in series with the pilots oxygen supply line to detect gas flow accompanying respiration.

  18. The effect of external dynamic loads on the lifetime of rolling element bearings: accurate measurement of the bearing behaviour

    NASA Astrophysics Data System (ADS)

    Jacobs, W.; Boonen, R.; Sas, P.; Moens, D.

    2012-05-01

    Accurate prediction of the lifetime of rolling element bearings is a crucial step towards a reliable design of many rotating machines. Recent research emphasizes an important influence of external dynamic loads on the lifetime of bearings. However, most lifetime calculations of bearings are based on the classical ISO 281 standard, neglecting this influence. For bearings subjected to highly varying loads, this leads to inaccurate estimations of the lifetime, and therefore excessive safety factors during the design and unexpected failures during operation. This paper presents a novel test rig, developed to analyse the behaviour of rolling element bearings subjected to highly varying loads. Since bearings are very precise machine components, their motion can only be measured in an accurately controlled environment. Otherwise, noise from other components and external influences such as temperature variations will dominate the measurements. The test rig is optimised to perform accurate measurements of the bearing behaviour. Also, the test bearing is fitted in a modular structure, which guarantees precise mounting and allows testing different types and sizes of bearings. Finally, a fully controlled multi-axial static and dynamic load is imposed on the bearing, while its behaviour is monitored with capacitive proximity probes.

  19. Spontaneous fluctuation indices of the cardiovagal baroreflex accurately measure the baroreflex sensitivity at the operating point during upright tilt.

    PubMed

    Schwartz, Christopher E; Medow, Marvin S; Messer, Zachary; Stewart, Julian M

    2013-06-15

    Spontaneous fluctuation indices of cardiovagal baroreflex have been suggested to be inaccurate measures of baroreflex function during orthostatic stress compared with alternate open-loop methods (e.g. neck pressure/suction, modified Oxford method). We therefore tested the hypothesis that spontaneous fluctuation measurements accurately reflect local baroreflex gain (slope) at the operating point measured by the modified Oxford method, and that apparent differences between these two techniques during orthostasis can be explained by a resetting of the baroreflex function curve. We computed the sigmoidal baroreflex function curves supine and during 70° tilt in 12 young, healthy individuals. With the use of the modified Oxford method, slopes (gains) of supine and upright curves were computed at their maxima (Gmax) and operating points. These were compared with measurements of spontaneous indices in both positions. Supine spontaneous analyses of operating point slope were similar to calculated Gmax of the modified Oxford curve. In contrast, upright operating point was distant from the centering point of the reset curve and fell on the nonlinear portion of the curve. Whereas spontaneous fluctuation measurements were commensurate with the calculated slope of the upright modified Oxford curve at the operating point, they were significantly lower than Gmax. In conclusion, spontaneous measurements of cardiovagal baroreflex function accurately estimate the slope near operating points in both supine and upright position.

  20. Describing and compensating gas transport dynamics for accurate instantaneous emission measurement

    NASA Astrophysics Data System (ADS)

    Weilenmann, Martin; Soltic, Patrik; Ajtay, Delia

    Instantaneous emission measurements on chassis dynamometers and engine test benches are becoming increasingly usual for car-makers and for environmental emission factor measurement and calculation, since much more information about the formation conditions can be extracted than from the regulated bag measurements (integral values). The common exhaust gas analysers for the "regulated pollutants" (carbon monoxide, total hydrocarbons, nitrogen oxide, carbon dioxide) allow measurement at a rate of one to ten samples per second. This gives the impression of having after-the-catalyst emission information with that chronological precision. It has been shown in recent years, however, that beside the reaction time of the analysers, the dynamics of gas transport in both the exhaust system of the car and the measurement system last significantly longer than 1 s. This paper focuses on the compensation of all these dynamics convoluting the emission signals. Most analysers show linear and time-invariant reaction dynamics. Transport dynamics can basically be split into two phenomena: a pure time delay accounting for the transport of the gas downstream and a dynamic signal deformation since the gas is mixed by turbulence along the way. This causes emission peaks to occur which are smaller in height and longer in time at the sensors than they are after the catalyst. These dynamics can be modelled using differential equations. Both mixing dynamics and time delay are constant for modelling a raw gas analyser system, since the flow in that system is constant. In the exhaust system of the car, however, the parameters depend on the exhaust volume flow. For gasoline cars, the variation in overall transport time may be more than 6 s. It is shown in this paper how all these processes can be described by invertible mathematical models with the focus on the more complex case of the car's exhaust system. Inversion means that the sharp emission signal at the catalyst out location can be

  1. A Procedure for Accurately Measuring the Shaker Overturning Moment During Random Vibration Tests

    NASA Technical Reports Server (NTRS)

    Nayeri, Reza D.

    2011-01-01

    Motivation: For large system level random vibration tests, there may be some concerns about the shaker's capability for the overturning moment. It is the test conductor's responsibility to predict and monitor the overturning moment during random vibration tests. If the predicted moment is close to the shaker's capability, test conductor must measure the instantaneous moment at low levels and extrapolate to higher levels. That data will be used to decide whether it is safe to proceed to the next test level. Challenge: Kistler analog formulation for computing the real-time moment is only applicable to very limited cases in which we have 3 or 4 load cells installed at shaker interface with hardware. Approach: To overcome that limitation, a simple procedure was developed for computing the overturning moment time histories using the measured time histories of the individual load cells.

  2. Optimum satellite orbits for accurate measurement of the earth's radiation budget, summary

    NASA Technical Reports Server (NTRS)

    Campbell, G. G.; Vonderhaar, T. H.

    1978-01-01

    The optimum set of orbit inclinations for the measurement of the earth radiation budget from spacially integrating sensor systems was estimated for two and three satellite systems. The best set of the two were satellites at orbit inclinations of 80 deg and 50 deg; of three the inclinations were 80 deg, 60 deg and 50 deg. These were chosen on the basis of a simulation of flat plate and spherical detectors flying over a daily varying earth radiation field as measured by the Nimbus 3 medium resolution scanners. A diurnal oscillation was also included in the emitted flux and albedo to give a source field as realistic as possible. Twenty three satellites with different inclinations and equator crossings were simulated, allowing the results of thousand of multisatellite sets to be intercompared. All were circular orbits of radius 7178 kilometers.

  3. Measuring Accurately Single-Phase Sinusoidal and Non-Sinusoidal Power.

    DTIC Science & Technology

    1983-01-01

    dc source. - 1 T Figure 2.2 Power Measuring Test Set-up Source: Robert L. Boylestad , Introductory Circuit Analysis (Ohio: Charles E. Merrill, 1977) p...Power Waveforms for the General Case. Source: Robert L. Boylestad , Introductory CircuitAnalysis (Ohio: Charles E. Merrill, 1968) p. 309. Note that the...Inductive Circuit Source: Robert L. Boylestad , Introductory Circuit Analysis (Ohio: Charles E. Merrill, 1968) p. 43-. and c) In a1 purely capacitive

  4. Development of Filtered Rayleigh Scattering for Accurate Measurement of Gas Velocity

    NASA Technical Reports Server (NTRS)

    Miles, Richard B.; Lempert, Walter R.

    1995-01-01

    The overall goals of this research were to develop new diagnostic tools capable of capturing unsteady and/or time-evolving, high-speed flow phenomena. The program centers around the development of Filtered Rayleigh Scattering (FRS) for velocity, temperature, and density measurement, and the construction of narrow linewidth laser sources which will be capable of producing an order MHz repetition rate 'burst' of high power pulses.

  5. Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

    NASA Astrophysics Data System (ADS)

    Dönsberg, Timo; Mäntynen, Henrik; Ikonen, Erkki

    2016-06-01

    The measurement uncertainty of illuminance and, consequently, luminous flux and luminous efficacy of LED lamps can be reduced with a recently introduced method based on the predictable quantum efficient detector (PQED). One of the most critical factors affecting the measurement uncertainty with the PQED method is the determination of the aperture area. This paper describes an upgrade to an optical method for direct determination of aperture area where superposition of equally spaced Gaussian laser beams is used to form a uniform irradiance distribution. In practice, this is accomplished by scanning the aperture in front of an intensity-stabilized laser beam. In the upgraded method, the aperture is attached to the PQED and the whole package is transversely scanned relative to the laser beam. This has the benefit of having identical geometry in the laser scanning of the aperture area and in the actual photometric measurement. Further, the aperture and detector assembly does not have to be dismantled for the aperture calibration. However, due to small acceptance angle of the PQED, differences between the diffraction effects of an overfilling plane wave and of a combination of Gaussian laser beams at the circular aperture need to be taken into account. A numerical calculation method for studying these effects is discussed in this paper. The calculation utilizes the Rayleigh-Sommerfeld diffraction integral, which is applied to the geometry of the PQED and the aperture. Calculation results for various aperture diameters and two different aperture-to-detector distances are presented.

  6. A technique for fast and accurate measurement of hand volumes using Archimedes' principle.

    PubMed

    Hughes, S; Lau, J

    2008-03-01

    A new technique for measuring hand volumes using Archimedes principle is described. The technique involves the immersion of a hand in a water container placed on an electronic balance. The volume is given by the change in weight divided by the density of water. This technique was compared with the more conventional technique of immersing an object in a container with an overflow spout and collecting and weighing the volume of overflow water. The hand volume of two subjects was measured. Hand volumes were 494 +/- 6 ml and 312 +/- 7 ml for the immersion method and 476 +/- 14 ml and 302 +/- 8 ml for the overflow method for the two subjects respectively. Using plastic test objects, the mean difference between the actual and measured volume was -0.3% and 2.0% for the immersion and overflow techniques respectively. This study shows that hand volumes can be obtained more quickly than the overflow method. The technique could find an application in clinics where frequent hand volumes are required.

  7. Regular, Fast and Accurate Airborne In-Situ Methane Measurements Around the Tropopause

    NASA Astrophysics Data System (ADS)

    Dyroff, Christoph; Rauthe-Schöch, Armin; Schuck, Tanja J.; Zahn, Andreas

    2013-04-01

    We present a laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft. The instrument is based on a commercial fast methane analyzer (FMA, Los Gatos Res.), which was modified for fully unattended employment. A laboratory characterization was performed and the results with emphasis on the precision, cross sensitivity to H2O, and accuracy are presented. An in-flight calibration strategy is described, that utilizes CH4 measurements obtained from flask samples taken during the same flights. By statistical comparison of the in-situ measurements with the flask samples we derive a total uncetrainty estimate of ~ 3.85 ppbv (1?) around the tropopause, and ~ 12.4 ppbv (1?) during aircraft ascent and descent. Data from the first two years of airborne operation are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere, with occasional crossings of the tropics on flights to southern Africa. With its high spatial resolution and high accuracy this data set is unprecedented in the highly important atmospheric layer of the tropopause.

  8. An experimental apparatus for Casimir torque measurements

    NASA Astrophysics Data System (ADS)

    Somers, David A. T.; Munday, Jeremy N.

    We have developed an experiment to measure the Casimir torque. In our experiment, a solid birefringent crystal causes a nematic liquid crystal director to rotate such that the extraordinary axes are aligned. A transparent and isotropic dielectric spacer layer is used to separate the two birefringent materials and an all-optical technique is used for detection. In this talk, we report on the progress of this experiment. Department of Physics, Institute for Research in Electronics and Applied Physics.

  9. Measures of Situation Awareness: An Experimental Evaluation

    DTIC Science & Technology

    1991-10-01

    occurrence from non- occurrence of the target event, referred to as sensitivity (Macmillan and Creelman , 1990). Because sensitivity declines if pilots are...Pollack and Norman, 1964; see also Craig, 1979; Macmillan and Creelman , 1990). Finally, avoidance failures were measured simply as the number of times...Wesley. Macmillan, N. A., & Creelman , C. D. (1990). Response bias: Characteristics of detection theory, threshold theory, and "non- parametric" indexes

  10. Examining factors that may influence accurate measurement of testosterone in sea turtles.

    PubMed

    Graham, Katherine M; Mylniczenko, Natalie D; Burns, Charlene M; Bettinger, Tammie L; Wheaton, Catharine J

    2016-01-01

    Differences in reported testosterone concentrations in male sea turtle blood samples are common in the veterinary literature, but may be accounted for by differences in sample handling and processing prior to assay. Therefore, our study was performed to determine best practices for testosterone analysis in male sea turtles (Caretta caretta and Chelonia mydas). Blood samples were collected into 5 collection tube types, and assay validation and measured testosterone concentrations were compared across different sample storage (fresh, refrigerated 1 week, or frozen), extraction (unextracted or ether-extracted), and processing treatment (untreated, homogenized, or dissociation reagent) conditions. Ether-extracted and dissociation reagent-treated samples validated in all conditions tested and are recommended for use, as unextracted samples validated only if assayed fresh. Dissociation reagent treatment was simpler to perform than ether extraction and resulted in total testosterone concentrations ~2.7-3.5 times greater than free testosterone measured in ether-extracted samples. Sample homogenization did not affect measured testosterone concentrations, and could be used to increase volume in gelled samples. An annual seasonal testosterone increase was observed in both species when ether extraction or dissociation reagent treatment was used. Annual deslorelin implant treatments in a Chelonia mydas male resulted in suppression of seasonal testosterone following the fourth treatment. Seasonal testosterone patterns resumed following discontinuation of deslorelin. Comparison of in-house and commercially available enzyme immunoassay kits revealed similar patterns of seasonal testosterone increases and deslorelin-induced suppression. Our study highlights the importance of methodological validation and provides laboratorians with best practices for testosterone enzyme immunoassay in sea turtles.

  11. The dark art of light measurement: accurate radiometry for low-level light therapy.

    PubMed

    Hadis, Mohammed A; Zainal, Siti A; Holder, Michelle J; Carroll, James D; Cooper, Paul R; Milward, Michael R; Palin, William M

    2016-05-01

    Lasers and light-emitting diodes are used for a range of biomedical applications with many studies reporting their beneficial effects. However, three main concerns exist regarding much of the low-level light therapy (LLLT) or photobiomodulation literature; (1) incomplete, inaccurate and unverified irradiation parameters, (2) miscalculation of 'dose,' and (3) the misuse of appropriate light property terminology. The aim of this systematic review was to assess where, and to what extent, these inadequacies exist and to provide an overview of 'best practice' in light measurement methods and importance of correct light measurement. A review of recent relevant literature was performed in PubMed using the terms LLLT and photobiomodulation (March 2014-March 2015) to investigate the contemporary information available in LLLT and photobiomodulation literature in terms of reporting light properties and irradiation parameters. A total of 74 articles formed the basis of this systematic review. Although most articles reported beneficial effects following LLLT, the majority contained no information in terms of how light was measured (73%) and relied on manufacturer-stated values. For all papers reviewed, missing information for specific light parameters included wavelength (3%), light source type (8%), power (41%), pulse frequency (52%), beam area (40%), irradiance (43%), exposure time (16%), radiant energy (74%) and fluence (16%). Frequent use of incorrect terminology was also observed within the reviewed literature. A poor understanding of photophysics is evident as a significant number of papers neglected to report or misreported important radiometric data. These errors affect repeatability and reliability of studies shared between scientists, manufacturers and clinicians and could degrade efficacy of patient treatments. Researchers need a physicist or appropriately skilled engineer on the team, and manuscript reviewers should reject papers that do not report beam measurement

  12. Possibility of detecting anisotropic expansion of the universe by very accurate astrometry measurements.

    PubMed

    Quercellini, Claudia; Quartin, Miguel; Amendola, Luca

    2009-04-17

    Refined astrometry measurements allow us to detect large-scale deviations from isotropy through real-time observations of changes in the angular separation between sources at cosmic distances. This "cosmic parallax" effect is a powerful consistency test of the Friedmann-Robertson-Walker metric and may set independent constraints on cosmic anisotropy. We apply this novel general test to Lemaitre-Tolman-Bondi cosmologies with off-center observers and show that future satellite missions such as Gaia might achieve accuracies that would put limits on the off-center distance which are competitive with cosmic microwave background dipole constraints.

  13. Integration of a silicon-based microprobe into a gear measuring instrument for accurate measurement of micro gears

    NASA Astrophysics Data System (ADS)

    Ferreira, N.; Krah, T.; Jeong, D. C.; Metz, D.; Kniel, K.; Dietzel, A.; Büttgenbach, S.; Härtig, F.

    2014-06-01

    The integration of silicon micro probing systems into conventional gear measuring instruments (GMIs) allows fully automated measurements of external involute micro spur gears of normal modules smaller than 1 mm. This system, based on a silicon microprobe, has been developed and manufactured at the Institute for Microtechnology of the Technische Universität Braunschweig. The microprobe consists of a silicon sensor element and a stylus which is oriented perpendicularly to the sensor. The sensor is fabricated by means of silicon bulk micromachining. Its small dimensions of 6.5 mm × 6.5 mm allow compact mounting in a cartridge to facilitate the integration into a GMI. In this way, tactile measurements of 3D microstructures can be realized. To enable three-dimensional measurements with marginal forces, four Wheatstone bridges are built with diffused piezoresistors on the membrane of the sensor. On the reverse of the membrane, the stylus is glued perpendicularly to the sensor on a boss to transmit the probing forces to the sensor element during measurements. Sphere diameters smaller than 300 µm and shaft lengths of 5 mm as well as measurement forces from 10 µN enable the measurements of 3D microstructures. Such micro probing systems can be integrated into universal coordinate measuring machines and also into GMIs to extend their field of application. Practical measurements were carried out at the Physikalisch-Technische Bundesanstalt by qualifying the microprobes on a calibrated reference sphere to determine their sensitivity and their physical dimensions in volume. Following that, profile and helix measurements were carried out on a gear measurement standard with a module of 1 mm. The comparison of the measurements shows good agreement between the measurement values and the calibrated values. This result is a promising basis for the realization of smaller probe diameters for the tactile measurement of micro gears with smaller modules.

  14. Rapid and accurate measurement of the frequency-frequency correlation function.

    PubMed

    Osborne, Derek G; Kubarych, Kevin J

    2013-07-25

    Using an implementation of heterodyne-detected vibrational echo spectroscopy, we show that equilibrium spectral diffusion caused by solvation dynamics can be measured in a fraction of the time required using traditional two-dimensional infrared spectroscopy. Spectrally resolved, heterodyne-detected rephasing and nonrephasing signals, recorded at a single delay between the first two pulses in a photon echo sequence, can be used to measure the full waiting time dependent spectral dynamics that are typically extracted from a series of 2D-IR spectra. Hence, data acquisition is accelerated by more than 1 order of magnitude, while permitting extremely fine sampling of the spectral dynamics during the waiting time between the second and third pulses. Using cymantrene (cyclopentadienyl manganese tricarbonyl, CpMn(CO)3) in alcohol solutions, we compare this novel approach--denoted rapidly acquired spectral diffusion (RASD)--with a traditional method using full 2D-IR spectra, finding excellent agreement. Though this approach is largely limited to isolated vibrational bands, we also show how to remove interference from cross-peaks that can produce characteristic modulations of the spectral dynamics through vibrational quantum beats.

  15. Non-VKA Oral Anticoagulants: Accurate Measurement of Plasma Drug Concentrations.

    PubMed

    Douxfils, Jonathan; Mani, Helen; Minet, Valentine; Devalet, Bérangère; Chatelain, Bernard; Dogné, Jean-Michel; Mullier, François

    2015-01-01

    Non-VKA oral anticoagulants (NOACs) have now widely reached the lucrative market of anticoagulation. While the marketing authorization holders claimed that no routine monitoring is required and that these compounds can be given at fixed doses, several evidences arisen from the literature tend to demonstrate the opposite. New data suggests that an assessment of the response at the individual level could improve the benefit-risk ratio of at least dabigatran. Information regarding the association of rivaroxaban and apixaban exposure and the bleeding risk is available in the drug approval package on the FDA website. These reviews suggest that accumulation of these compounds increases the risk of experiencing a bleeding complication. Therefore, in certain patient populations such as patients with acute or chronic renal impairment or with multiple drug interactions, measurement of drug exposure may be useful to ensure an optimal treatment response. More specific circumstances such as patients experiencing a haemorrhagic or thromboembolic event during the treatment duration, patients who require urgent surgery or an invasive procedure, or patient with a suspected overdose could benefit from such a measurement. This paper aims at providing guidance on how to best estimate the intensity of anticoagulation using laboratory assays in daily practice.

  16. Quantitatively accurate activity measurements with a dedicated cardiac SPECT camera: Physical phantom experiments

    SciTech Connect

    Pourmoghaddas, Amir Wells, R. Glenn

    2016-01-15

    Purpose: Recently, there has been increased interest in dedicated cardiac single photon emission computed tomography (SPECT) scanners with pinhole collimation and improved detector technology due to their improved count sensitivity and resolution over traditional parallel-hole cameras. With traditional cameras, energy-based approaches are often used in the clinic for scatter compensation because they are fast and easily implemented. Some of the cardiac cameras use cadmium-zinc-telluride (CZT) detectors which can complicate the use of energy-based scatter correction (SC) due to the low-energy tail—an increased number of unscattered photons detected with reduced energy. Modified energy-based scatter correction methods can be implemented, but their level of accuracy is unclear. In this study, the authors validated by physical phantom experiments the quantitative accuracy and reproducibility of easily implemented correction techniques applied to {sup 99m}Tc myocardial imaging with a CZT-detector-based gamma camera with multiple heads, each with a single-pinhole collimator. Methods: Activity in the cardiac compartment of an Anthropomorphic Torso phantom (Data Spectrum Corporation) was measured through 15 {sup 99m}Tc-SPECT acquisitions. The ratio of activity concentrations in organ compartments resembled a clinical {sup 99m}Tc-sestamibi scan and was kept consistent across all experiments (1.2:1 heart to liver and 1.5:1 heart to lung). Two background activity levels were considered: no activity (cold) and an activity concentration 1/10th of the heart (hot). A plastic “lesion” was placed inside of the septal wall of the myocardial insert to simulate the presence of a region without tracer uptake and contrast in this lesion was calculated for all images. The true net activity in each compartment was measured with a dose calibrator (CRC-25R, Capintec, Inc.). A 10 min SPECT image was acquired using a dedicated cardiac camera with CZT detectors (Discovery NM530c, GE

  17. How accurately can subject-specific finite element models predict strains and strength of human femora? Investigation using full-field measurements.

    PubMed

    Grassi, Lorenzo; Väänänen, Sami P; Ristinmaa, Matti; Jurvelin, Jukka S; Isaksson, Hanna

    2016-03-21

    Subject-specific finite element models have been proposed as a tool to improve fracture risk assessment in individuals. A thorough laboratory validation against experimental data is required before introducing such models in clinical practice. Results from digital image correlation can provide full-field strain distribution over the specimen surface during in vitro test, instead of at a few pre-defined locations as with strain gauges. The aim of this study was to validate finite element models of human femora against experimental data from three cadaver femora, both in terms of femoral strength and of the full-field strain distribution collected with digital image correlation. The results showed a high accuracy between predicted and measured principal strains (R(2)=0.93, RMSE=10%, 1600 validated data points per specimen). Femoral strength was predicted using a rate dependent material model with specific strain limit values for yield and failure. This provided an accurate prediction (<2% error) for two out of three specimens. In the third specimen, an accidental change in the boundary conditions occurred during the experiment, which compromised the femoral strength validation. The achieved strain accuracy was comparable to that obtained in state-of-the-art studies which validated their prediction accuracy against 10-16 strain gauge measurements. Fracture force was accurately predicted, with the predicted failure location being very close to the experimental fracture rim. Despite the low sample size and the single loading condition tested, the present combined numerical-experimental method showed that finite element models can predict femoral strength by providing a thorough description of the local bone mechanical response.

  18. Accurate measurements of thermodynamic properties of solutes in ionic liquids using inverse gas chromatography.

    PubMed

    Mutelet, Fabrice; Jaubert, Jean-Noël

    2006-01-13

    Activity coefficients at infinite dilution of 29 organic compounds in two room temperature ionic liquids were determined using inverse gas chromatography. The measurements were carried out at different temperatures between 323.15 and 343.15K. To establish the influence of concurrent retention mechanisms on the accuracy of activity coefficients at infinite dilution for 1-butyl-3-methylimidazolium octyl sulfate and 1-ethyl-3-methylimidazolium tosylate, phase loading studies of the net retention volume per gram of packing as a function of the percent phase loading were used. It is shown that most of the solutes are retained largely by partition with a small contribution from adsorption on 1-butyl-3-methylimidazolium octyl sulfate and that the n-alkanes are retained predominantly by interfacial adsorption on 1-ethyl-3-methylimidazolium tosylate.

  19. Numerical simulation and analysis of accurate blood oxygenation measurement by using optical resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Yu, Tianhao; Li, Qian; Li, Lin; Zhou, Chuanqing

    2016-10-01

    Accuracy of photoacoustic signal is the crux on measurement of oxygen saturation in functional photoacoustic imaging, which is influenced by factors such as defocus of laser beam, curve shape of large vessels and nonlinear saturation effect of optical absorption in biological tissues. We apply Monte Carlo model to simulate energy deposition in tissues and obtain photoacoustic signals reaching a simulated focused surface detector to investigate corresponding influence of these factors. We also apply compensation on photoacoustic imaging of in vivo cat cerebral cortex blood vessels, in which signals from different lateral positions of vessels are corrected based on simulation results. And this process on photoacoustic images can improve the smoothness and accuracy of oxygen saturation results.

  20. Combined atomic force microscopy and voltage pulse technique to accurately measure electrostatic force

    NASA Astrophysics Data System (ADS)

    Inami, Eiichi; Sugimoto, Yoshiaki

    2016-08-01

    We propose a new method of extracting electrostatic force. The technique is based on frequency modulation atomic force microscopy (FM-AFM) combined with a voltage pulse. In this method, the work that the electrostatic field does on the oscillating tip is measured through the cantilever energy dissipation. This allows us to directly extract capacitive forces including the longer range part, to which the conventional FM-AFM is insensitive. The distance-dependent contact potential difference, which is modulated by local charges distributed on the surfaces of the tip and/or sample, could also be correctly obtained. In the absence of local charges, our method can perfectly reproduce the electrostatic force as a function of the distance and the bias voltage. Furthermore, we demonstrate that the system serves as a sensitive sensor enabling us to check the existence of the local charges such as trapped charges and patch charges.

  1. Reliable and Accurate Calcium Volume Measurement in Coronary Artery Using Intravascular Ultrasound Videos.

    PubMed

    Araki, Tadashi; Banchhor, Sumit K; Londhe, Narendra D; Ikeda, Nobutaka; Radeva, Petia; Shukla, Devarshi; Saba, Luca; Balestrieri, Antonella; Nicolaides, Andrew; Shafique, Shoaib; Laird, John R; Suri, Jasjit S

    2016-03-01

    Quantitative assessment of calcified atherosclerotic volume within the coronary artery wall is vital for cardiac interventional procedures. The goal of this study is to automatically measure the calcium volume, given the borders of coronary vessel wall for all the frames of the intravascular ultrasound (IVUS) video. Three soft computing fuzzy classification techniques were adapted namely Fuzzy c-Means (FCM), K-means, and Hidden Markov Random Field (HMRF) for automated segmentation of calcium regions and volume computation. These methods were benchmarked against previously developed threshold-based method. IVUS image data sets (around 30,600 IVUS frames) from 15 patients were collected using 40 MHz IVUS catheter (Atlantis® SR Pro, Boston Scientific®, pullback speed of 0.5 mm/s). Calcium mean volume for FCM, K-means, HMRF and threshold-based method were 37.84 ± 17.38 mm(3), 27.79 ± 10.94 mm(3), 46.44 ± 19.13 mm(3) and 35.92 ± 16.44 mm(3) respectively. Cross-correlation, Jaccard Index and Dice Similarity were highest between FCM and threshold-based method: 0.99, 0.92 ± 0.02 and 0.95 + 0.02 respectively. Student's t-test, z-test and Wilcoxon-test are also performed to demonstrate consistency, reliability and accuracy of the results. Given the vessel wall region, the system reliably and automatically measures the calcium volume in IVUS videos. Further, we validated our system against a trained expert using scoring: K-means showed the best performance with an accuracy of 92.80%. Out procedure and protocol is along the line with method previously published clinically.

  2. Accurate measurement of silver isotopic compositions in geological materials including low Pd/Ag meteorites

    NASA Astrophysics Data System (ADS)

    Woodland, S. J.; Rehkämper, M.; Halliday, A. N.; Lee, D.-C.; Hattendorf, B.; Günther, D.

    2005-04-01

    Very precise silver (Ag) isotopic compositions have been determined for a number of terrestrial rocks, and high and low Pd/Ag meteorites by utilizing multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The meteorites include primitive chondrites, the Group IAB iron meteorites Canyon Diablo and Toluca, and the Group IIIAB iron meteorite Grant. Silver isotopic measurements are primarily of interest because 107Ag was produced by decay of the short-lived radionuclide 107Pd during the formation of the solar system and hence the Pd-Ag chronometer has set constraints on the timing of early planetesimal formation. A 2σ precision of ±0.05‰ can be obtained for analyses of standard solutions when Ag isotopic ratios are normalized to Pd, to correct for instrumental mass discrimination, and to bracketing standards. Caution must be exercised when making Ag isotopic measurements because isotopic artifacts can be generated in the laboratory and during mass spectrometry. The external reproducibility for geological samples based on replicate analyses of rocks is ±0.2‰ (2σ). All chondrites analyzed have similar Ag isotopic compositions that do not differ significantly (>0.3‰) from the 'terrestrial' value of the NIST SRM 978a Ag isotope standard. Hence, they show no evidence of excess 107Ag derived from 107Pd decay or, of stable Ag isotope fractionation associated with volatile element depletion within the accretion disk or from parent body metamorphism. The Group IAB iron meteorite samples analyzed show evidence of complex behavior and disturbance of Ag isotope systematics. Therefore, care must be taken when using this group of iron meteorites to obtain chronological information based on the Pd-Ag decay scheme.

  3. Measurements of accurate x-ray scattering data of protein solutions using small stationary sample cells

    SciTech Connect

    Hong Xinguo; Hao Quan

    2009-01-15

    In this paper, we report a method of precise in situ x-ray scattering measurements on protein solutions using small stationary sample cells. Although reduction in the radiation damage induced by intense synchrotron radiation sources is indispensable for the correct interpretation of scattering data, there is still a lack of effective methods to overcome radiation-induced aggregation and extract scattering profiles free from chemical or structural damage. It is found that radiation-induced aggregation mainly begins on the surface of the sample cell and grows along the beam path; the diameter of the damaged region is comparable to the x-ray beam size. Radiation-induced aggregation can be effectively avoided by using a two-dimensional scan (2D mode), with an interval as small as 1.5 times the beam size, at low temperature (e.g., 4 deg. C). A radiation sensitive protein, bovine hemoglobin, was used to test the method. A standard deviation of less than 5% in the small angle region was observed from a series of nine spectra recorded in 2D mode, in contrast to the intensity variation seen using the conventional stationary technique, which can exceed 100%. Wide-angle x-ray scattering data were collected at a standard macromolecular diffraction station using the same data collection protocol and showed a good signal/noise ratio (better than the reported data on the same protein using a flow cell). The results indicate that this method is an effective approach for obtaining precise measurements of protein solution scattering.

  4. Measurements of accurate x-ray scattering data of protein solutions using small stationary sample cells

    NASA Astrophysics Data System (ADS)

    Hong, Xinguo; Hao, Quan

    2009-01-01

    In this paper, we report a method of precise in situ x-ray scattering measurements on protein solutions using small stationary sample cells. Although reduction in the radiation damage induced by intense synchrotron radiation sources is indispensable for the correct interpretation of scattering data, there is still a lack of effective methods to overcome radiation-induced aggregation and extract scattering profiles free from chemical or structural damage. It is found that radiation-induced aggregation mainly begins on the surface of the sample cell and grows along the beam path; the diameter of the damaged region is comparable to the x-ray beam size. Radiation-induced aggregation can be effectively avoided by using a two-dimensional scan (2D mode), with an interval as small as 1.5 times the beam size, at low temperature (e.g., 4 °C). A radiation sensitive protein, bovine hemoglobin, was used to test the method. A standard deviation of less than 5% in the small angle region was observed from a series of nine spectra recorded in 2D mode, in contrast to the intensity variation seen using the conventional stationary technique, which can exceed 100%. Wide-angle x-ray scattering data were collected at a standard macromolecular diffraction station using the same data collection protocol and showed a good signal/noise ratio (better than the reported data on the same protein using a flow cell). The results indicate that this method is an effective approach for obtaining precise measurements of protein solution scattering.

  5. Experimental flux measurements on a network scale

    SciTech Connect

    Schwender, J.

    2011-10-11

    Metabolic flux is a fundamental property of living organisms. In recent years, methods for measuring metabolic flux in plants on a network scale have evolved further. One major challenge in studying flux in plants is the complexity of the plant's metabolism. In particular, in the presence of parallel pathways in multiple cellular compartments, the core of plant central metabolism constitutes a complex network. Hence, a common problem with the reliability of the contemporary results of {sup 13}C-Metabolic Flux Analysis in plants is the substantial reduction in complexity that must be included in the simulated networks; this omission partly is due to limitations in computational simulations. Here, I discuss recent emerging strategies that will better address these shortcomings.

  6. Development of Accurate Chemical Equilibrium Models for the Hanford Waste Tanks: New Thermodynamic Measurements and Model Applications

    SciTech Connect

    Felmy, Andrew R.; Mason, Marvin; Qafoku, Odeta; Xia, Yuanxian; Wang, Zheming; MacLean, Graham

    2003-03-27

    Developing accurate thermodynamic models for predicting the chemistry of the high-level waste tanks at Hanford is an extremely daunting challenge in electrolyte and radionuclide chemistry. These challenges stem from the extremely high ionic strength of the tank waste supernatants, presence of chelating agents in selected tanks, wide temperature range in processing conditions and the presence of important actinide species in multiple oxidation states. This presentation summarizes progress made to date in developing accurate models for these tank waste solutions, how these data are being used at Hanford and the important challenges that remain. New thermodynamic measurements on Sr and actinide complexation with specific chelating agents (EDTA, HEDTA and gluconate) will also be presented.

  7. First accurate experimental study of Mu reactivity from a state-selected reactant in the gas phase: the Mu + H2{1} reaction rate at 300 K

    NASA Astrophysics Data System (ADS)

    Bakule, Pavel; Sukhorukov, Oleksandr; Ishida, Katsuhiko; Pratt, Francis; Fleming, Donald; Momose, Takamasa; Matsuda, Yasuyuki; Torikai, Eiko

    2015-02-01

    This paper reports on the experimental background and methodology leading to recent results on the first accurate measurement of the reaction rate of the muonium (Mu) atom from a state-selected reactant in the gas phase: the Mu + H2\\{1\\}\\to MuH + H reaction at 300 K, and its comparison with rigorous quantum rate theory, Bakule et al (2012 J. Phys. Chem. Lett. 3 2755). Stimulated Raman pumping, induced by 532 nm light from the 2nd harmonic of a Nd:YAG laser, was used to produce H2 in its first vibrational (v = 1) state, H2\\{1\\}, in a single Raman/reaction cell. A pulsed muon beam (from ‘ISIS’, at 50 Hz) matched the 25 Hz repetition rate of the laser, allowing data taking in equal ‘Laser-On/Laser-Off’ modes of operation. The signal to noise was improved by over an order of magnitude in comparison with an earlier proof-of-principle experiment. The success of the present experiment also relied on optimizing the overlap of the laser profile with the extended stopping distribution of the muon beam at 50 bar H2 pressure, in which Monte Carlo simulations played a central role. The rate constant, found from the analysis of three separate measurements, which includes a correction for the loss of {{H}2}\\{1\\} concentration due to collisional relaxation with unpumped H2 during the time of each measurement, is {{k}Mu}\\{1\\} = 9.9[(-1.4)(+1.7)] × 10-13 cm3 s-1 at 300 K. This is in good to excellent agreement with rigorous quantum rate calculations on the complete configuration interaction/Born-Huang surface, as reported earlier by Bakule et al, and which are also briefly commented on herein.

  8. S3 HMBC hetero: Spin-State-Selective HMBC for accurate measurement of long-range heteronuclear coupling constants

    NASA Astrophysics Data System (ADS)

    Hoeck, Casper; Gotfredsen, Charlotte H.; Sørensen, Ole W.

    2017-02-01

    A novel method, Spin-State-Selective (S3) HMBC hetero, for accurate measurement of heteronuclear coupling constants is introduced. The method extends the S3 HMBC technique for measurement of homonuclear coupling constants by appending a pulse sequence element that interchanges the polarization in 13C-1H methine pairs. This amounts to converting the spin-state selectivity from 1H spin states to 13C spin states in the spectra of long-range coupled 1H spins, allowing convenient measurement of heteronuclear coupling constants similar to other S3 or E.COSY-type methods. As usual in this type of techniques, the accuracy of coupling constant measurement is independent of the size of the coupling constant of interest. The merits of the new method are demonstrated by application to vinyl acetate, the alkaloid strychnine, and the carbohydrate methyl β-maltoside.

  9. Standardization of vitrinite reflectance measurements in shale petroleum systems: How accurate are my Ro data?

    USGS Publications Warehouse

    Hackley, Paul C.

    2014-01-01

    Vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation. However, until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale. Efforts to correct this deficiency resulted in publication of ASTM D7708-11: Standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks. In 2012-2013, an interlaboratory exercise was conducted to establish precision limits for the measurement technique. Six samples, representing a wide variety of shale, were tested in duplicate by 28 analysts in 22 laboratories from 14 countries. Samples ranged from immature to overmature (Ro 0.31-1.53%), from organic-rich to organic-lean (1-22 wt.% total organic carbon), and contained Type I (lacustrine), Type II (marine), and Type III (terrestrial) kerogens. Repeatability values (difference between repetitive results from same operator, same conditions) ranged from 0.03-0.11% absolute reflectance, whereas reproducibility values (difference between results obtained on same test material by different operators, different laboratories) ranged from 0.12-0.54% absolute reflectance. Repeatability and reproducibility degraded consistently with increasing maturity and decreasing organic content. However, samples with terrestrial kerogens (Type III) fell off this trend, showing improved levels of reproducibility due to higher vitrinite content and improved ease of identification. Operators did not consistently meet the reporting requirements of the test method, indicating that a common reporting template is required to improve data quality. The most difficult problem encountered was the petrographic distinction of solid bitumens and low-reflecting inert macerals from vitrinite when vitrinite occurred with reflectance ranges overlapping the other components. Discussion among

  10. Accurate weak lensing of standard candles. II. Measuring σ8 with supernovae

    NASA Astrophysics Data System (ADS)

    Quartin, Miguel; Marra, Valerio; Amendola, Luca

    2014-01-01

    Soon the number of type Ia supernova (SN) measurements should exceed 100 000. Understanding the effect of weak lensing by matter structures on the supernova brightness will then be more important than ever. Although SN lensing is usually seen as a source of systematic noise, we will show that it can be in fact turned into signal. More precisely, the non-Gaussianity introduced by lensing in the SN Hubble diagram dispersion depends rather sensitively on the amplitude σ8 of the matter power spectrum. By exploiting this relation, we are able to predict constraints on σ8 of 7% (3%) for a catalog of 100 000 (500 000) SNe of average magnitude error 0.12, without having to assume that such intrinsic dispersion and its redshift evolution are known a priori. The intrinsic dispersion has been assumed to be Gaussian; possible intrinsic non-Gaussianities in the data set (due to the SN themselves and/or to other transients) could be potentially dealt with by means of additional nuisance parameters describing higher moments of the intrinsic dispersion distribution function. This method is independent of and complementary to the standard methods based on cosmic microwave background, cosmic shear, or cluster abundance observables.

  11. EZ-Rhizo: integrated software for the fast and accurate measurement of root system architecture.

    PubMed

    Armengaud, Patrick; Zambaux, Kevin; Hills, Adrian; Sulpice, Ronan; Pattison, Richard J; Blatt, Michael R; Amtmann, Anna

    2009-03-01

    The root system is essential for the growth and development of plants. In addition to anchoring the plant in the ground, it is the site of uptake of water and minerals from the soil. Plant root systems show an astonishing plasticity in their architecture, which allows for optimal exploitation of diverse soil structures and conditions. The signalling pathways that enable plants to sense and respond to changes in soil conditions, in particular nutrient supply, are a topic of intensive research, and root system architecture (RSA) is an important and obvious phenotypic output. At present, the quantitative description of RSA is labour intensive and time consuming, even using the currently available software, and the lack of a fast RSA measuring tool hampers forward and quantitative genetics studies. Here, we describe EZ-Rhizo: a Windows-integrated and semi-automated computer program designed to detect and quantify multiple RSA parameters from plants growing on a solid support medium. The method is non-invasive, enabling the user to follow RSA development over time. We have successfully applied EZ-Rhizo to evaluate natural variation in RSA across 23 Arabidopsis thaliana accessions, and have identified new RSA determinants as a basis for future quantitative trait locus (QTL) analysis.

  12. Accurate thickness/density measurements of organic light-emitting diodes

    SciTech Connect

    Maree, C.H.; Weller, R.A.; Feldman, L.C.; Pakbaz, K.; Lee, H.W.

    1998-10-01

    We report on the use of Rutherford backscattering spectroscopy for thickness analysis of organic light-emitting diode structures (OLEDs) with subnanometer resolution and a spatial resolution {lt}1thinspmm. A careful study of ion beam induced effects revealed some organic film degradation, but not so severe as to inhibit meaningful measurements. The method is independent of the substrate and is still applicable if the organic film is capped with a metal cathode. Common OLED materials have been the subject of this study: poly(2-methoxy,5-(2{sup {prime}}-ethylhexoxy)-1,4-phenylene-vinylene) (MEH-PPV), N{sup {prime}},N{sup {prime}}-diphenyl-N, N{sup {prime}}-bis(3-methylphenyl)-1,1{sup {prime}} biphenyl-4,4{sup {prime}}-diamine (TPD), and tris-(8-hydroxyquinoline) aluminum (Alq{sub 3}). The densities of thin films of evaporated TPD ({rho}=1.22{plus_minus}0.05thinspg/cm{sup 3}) and Alq{sub 3} ({rho}=1.51{plus_minus}0.03thinspg/cm{sup 3}) have been established. {copyright} {ital 1998 American Institute of Physics.}

  13. Accurate measurement of the sticking time and sticking probability of Rb atoms on a polydimethylsiloxane coating

    SciTech Connect

    Atutov, S. N. Plekhanov, A. I.

    2015-01-15

    We present the results of a systematic study of Knudsen’s flow of Rb atoms in cylindrical capillary cells coated with a polydimethylsiloxane (PDMS) compound. The purpose of the investigation is to determine the characterization of the coating in terms of the sticking probability and sticking time of Rb on the two types of coating of high and medium viscosities. We report the measurement of the sticking probability of a Rb atom to the coating equal to 4.3 × 10{sup −5}, which corresponds to the number of bounces 2.3 × 10{sup 4} at room temperature. These parameters are the same for the two kinds of PDMS used. We find that at room temperature, the respective sticking times for high-viscosity and medium-viscosity PDMS are 22 ± 3 μs and 49 ± 6 μs. These sticking times are about million times larger than the sticking time derived from the surface Rb atom adsorption energy and temperature of the coating. A tentative explanation of this surprising result is proposed based on the bulk diffusion of the atoms that collide with the surface and penetrate inside the coating. The results can be important in many resonance cell experiments, such as the efficient magnetooptical trapping of rare elements or radioactive isotopes and in experiments on the light-induced drift effect.

  14. Experimental measurements of shock properties of stishovite

    SciTech Connect

    Furnish, M.D.; Ito, E.

    1995-10-01

    We have synthesized, characterized and performed Hugoniot measurements on monolithic samples of stishovite, a high pressure polymorph of silica. Synthesis was accomplished in a multianvil press with pyrophyllite gaskets and carbon heaters. The samples had densities ranging from 3.80 to 4.07, corresponding to stishovite volume fractions of 0.7 to 0.87, a range confirmed by NMR analysis. They had no significant impurities except less than 1% carbon. Samples {approximately} 1 mm thick and 3 mm diameter were tested in reverse- and forward-ballistics modes on a two-stage light gas gun, using velocity interferometry diagnostics. Impact velocities ranged from 4.0 to 6.5 km/sec. Hugoniot stresses for the four successful tests ranged from 65 to 225GPa. At higher stresses significant uncertainties arise due to impact tilt/nonplanariy issues. Results are consistent with earlier predictions of the stishovite Hugoniot based on quartz-centered Hugoniot data, static-compression (diamond-anvil cell) data and hydrostatic multianvil cell data. Release behavior appears to be frozen. These results are remarkable in view of the small size of the samples used.

  15. 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

  16. Do anthropometric indices accurately reflect directly measured body composition in men and women with chronic heart failure?

    PubMed

    Oreopoulos, Antigone; Fonarow, Gregg C; Ezekowitz, Justin A; McAlister, Finlay A; Sharma, Arya M; Kalantar-Zadeh, Kamyar; Norris, Colleen M; Johnson, Jeffery A; Padwal, Raj S

    2011-01-01

    How well anthropometric indices such as body mass index (BMI), waist circumference, waist-stature ratio, and waist index correlate with direct measures of body composition (lean body mass, body fat) in men and women with chronic heart failure (CHF) has not been reported. Body composition was assessed by dual-energy x-ray absorptiometry in 140 patients with CHF. Age-adjusted Pearson correlations between each index and measures of body composition for men and women were calculated. Diagnostic accuracy of detecting obesity or high central fat was also examined. In men, all of the anthropometric indices except waist index were just as strongly correlated with lean body mass (correlation coefficients varied between 0.56 for waist-stature ratio to 0.74 for BMI) as with percentage of body fat (correlation coefficients varied between 0.72 for BMI to 0.79 for waist circumference). In women, all 4 anthropometric measures were unable to significantly differentiate between body fat and lean body mass. The positive likelihood ratios for the detection of obesity varied between 2.26 for waist circumference and 3.42 for BMI, waist-stature ratio, and waist index. Anthropometric indices do not accurately reflect body composition in patients with CHF, especially in women. When accurate assessment of body composition is required, direct measurements should be obtained.

  17. A systematic approach for the accurate and rapid measurement of water vapor transmission through ultra-high barrier films

    NASA Astrophysics Data System (ADS)

    Kiese, Sandra; Kücükpinar, Esra; Reinelt, Matthias; Miesbauer, Oliver; Ewender, Johann; Langowski, Horst-Christian

    2017-02-01

    Flexible organic electronic devices are often protected from degradation by encapsulation in multilayered films with very high barrier properties against moisture and oxygen. However, metrology must be improved to detect such low quantities of permeants. We therefore developed a modified ultra-low permeation measurement device based on a constant-flow carrier-gas system to measure both the transient and stationary water vapor permeation through high-performance barrier films. The accumulation of permeated water vapor before its transport to the detector allows the measurement of very low water vapor transmission rates (WVTRs) down to 2 × 10-5 g m-2 d-1. The measurement cells are stored in a temperature-controlled chamber, allowing WVTR measurements within the temperature range 23-80 °C. Differences in relative humidity can be controlled within the range 15%-90%. The WVTR values determined using the novel measurement device agree with those measured using a commercially available carrier-gas device from MOCON®. Depending on the structure and quality of the barrier film, it may take a long time for the WVTR to reach a steady-state value. However, by using a combination of the time-dependent measurement and the finite element method, we were able to estimate the steady-state WVTR accurately with significantly shorter measurement times.

  18. Experimental measurements of the Hugoniot of stishovite

    SciTech Connect

    Furnish, M.D.; Ito, Eichi

    1995-10-01

    The crust and mantle of the Earth are primarily composed of silicates. The properties of these materials under compression are of interest for deducing deep-earth composition. As well, the properties of these materials under shock compression are of interest for calculating groundshock propagation. The authors have synthesized, characterized, and performed Hugoniot measurements on monolithic polycrystalline SiO{sub 2} samples which were predominantly stishovite (a high-pressure polymorph). Synthesis was accomplished in a multianvil press with pyrophyllite gaskets and carbon heaters. The samples had densities ranging from 3.80 to 4.07, corresponding to stishovite volume fractions of 0.7 to 0.87, a range confirmed by NMR analysis. Electron microprobe and X-ray fluorescence characterizations showed minor carbon contamination (< 1%), with no other significant impurities. Samples {approximately} 1 mm thick and 3 mm diameter were tested in reverse and forward-ballistics modes on a two-stage light gas gun, using velocity interferometry diagnostics. Impact velocities ranged from 4.0 to 6.5 km/sec. Hugoniot stresses for four tests ranged from 65 to 225 GPa. At higher stresses significant uncertainties arise due to impact tilt/nonplanarity issues. Results are consistent with earlier predictions of the stishovite Hugoniot based on quartz-centered Hugoniot data, static-compression (diamond-anvil cell) data and hydrostatic multianvil cell data. Release behavior appears to be frozen. These results are remarkable in view of the small size of the samples used. Results are compared with current EOS models.

  19. Accurate measurement of dispersion data through short and narrow tubes used in very high-pressure liquid chromatography.

    PubMed

    Gritti, Fabrice; McDonald, Thomas; Gilar, Martin

    2015-09-04

    An original method is proposed for the accurate and reproducible measurement of the time-based dispersion properties of short L< 50cm and narrow rc< 50μm tubes at mobile phase flow rates typically used in very high-pressure liquid chromatography (vHPLC). Such tubes are used to minimize sample dispersion in vHPLC; however, their dispersion characteristics cannot be accurately measured at such flow rates due to system dispersion contribution of vHPLC injector and detector. It is shown that using longer and wider tubes (>10μL) enables a reliable measurement of the dispersion data. We confirmed that the dimensionless plot of the reduced dispersion coefficient versus the reduced linear velocity (Peclet number) depends on the aspect ratio, L/rc, of the tube, and unexpectedly also on the diffusion coefficient of the analyte. This dimensionless plot could be easily obtained for a large volume tube, which has the same aspect ratio as that of the short and narrow tube, and for the same diffusion coefficient. The dispersion data for the small volume tube are then directly extrapolated from this plot. For instance, it is found that the maximum volume variances of 75μm×30.5cm and 100μm×30.5cm prototype finger-tightened connecting tubes are 0.10 and 0.30μL(2), respectively, with an accuracy of a few percent and a precision smaller than seven percent.

  20. Compensation method for obtaining accurate, sub-micrometer displacement measurements of immersed specimens using electronic speckle interferometry.

    PubMed

    Fazio, Massimo A; Bruno, Luigi; Reynaud, Juan F; Poggialini, Andrea; Downs, J Crawford

    2012-03-01

    We proposed and validated a compensation method that accounts for the optical distortion inherent in measuring displacements on specimens immersed in aqueous solution. A spherically-shaped rubber specimen was mounted and pressurized on a custom apparatus, with the resulting surface displacements recorded using electronic speckle pattern interferometry (ESPI). Point-to-point light direction computation is achieved by a ray-tracing strategy coupled with customized B-spline-based analytical representation of the specimen shape. The compensation method reduced the mean magnitude of the displacement error induced by the optical distortion from 35% to 3%, and ESPI displacement measurement repeatability showed a mean variance of 16 nm at the 95% confidence level for immersed specimens. The ESPI interferometer and numerical data analysis procedure presented herein provide reliable, accurate, and repeatable measurement of sub-micrometer deformations obtained from pressurization tests of spherically-shaped specimens immersed in aqueous salt solution. This method can be used to quantify small deformations in biological tissue samples under load, while maintaining the hydration necessary to ensure accurate material property assessment.

  1. Accurate measurement of optical properties of narrow leaves and conifer needles with a typical integrating sphere and spectroradiometer.

    PubMed

    Noda, Hibiki M; Motohka, Takeshi; Murakami, Kazutaka; Muraoka, Hiroyuki; Nasahara, Kenlo Nishida

    2013-10-01

    Accurate information on the optical properties (reflectance and transmittance spectra) of single leaves is important for an ecophysiological understanding of light use by leaves, radiative transfer models and remote sensing of terrestrial ecosystems. In general, leaf optical properties are measured with an integrating sphere and a spectroradiometer. However, this method is usually difficult to use with grass leaves and conifer needles because they are too narrow to cover the sample port of a typical integrating sphere. Although ways to measure the optical properties of narrow leaves have been suggested, they have problems. We propose a new measurement protocol and calculation algorithms. The protocol does not damage sample leaves and is valid for various types of leaves, including green and senescent. We tested our technique with leaves of Aucuba japonica, an evergreen broadleaved shrub, and compared the spectral data of whole leaves and narrow strips of the leaves. The reflectance and transmittance of the strips matched those of the whole leaves, indicating that our technique can accurately estimate the optical properties of narrow leaves. Tests of conifer needles confirmed the applicability.

  2. A simple and inclusive method to determine the habit plane in transmission electron microscope based on accurate measurement of foil thickness

    SciTech Connect

    Qiu, Dong Zhang, Mingxing

    2014-08-15

    A simple and inclusive method is proposed for accurate determination of the habit plane between bicrystals in transmission electron microscope. Whilst this method can be regarded as a variant of surface trace analysis, the major innovation lies in the improved accuracy and efficiency of foil thickness measurement, which involves a simple tilt of the thin foil about a permanent tilting axis of the specimen holder, rather than cumbersome tilt about the surface trace of the habit plane. Experimental study has been done to validate this proposed method in determining the habit plane between lamellar α{sub 2} plates and γ matrix in a Ti–Al–Nb alloy. Both high accuracy (± 1°) and high precision (± 1°) have been achieved by using the new method. The source of the experimental errors as well as the applicability of this method is discussed. Some tips to minimise the experimental errors are also suggested. - Highlights: • An improved algorithm is formulated to measure the foil thickness. • Habit plane can be determined with a single tilt holder based on the new algorithm. • Better accuracy and precision within ± 1° are achievable using the proposed method. • The data for multi-facet determination can be collected simultaneously.

  3. Accurately measuring 'green' credentials.

    PubMed

    Túnica, José; Planas, Carla; Clemente, Raquel

    2013-08-01

    In a slightly adapted version of article first published in the IFHE (International Federation of Hospital Engineering) Digest 2012, José Túnica, managing director, Carla Planas, BREEAM assessor, and Raquel Clemente, LEED AP BREEAM assessor, at Spanish independent engineering firm, JG Ingenieros, examine the impact on the design of hospitals and other healthcare buildings of some of the key environmental assessment schemes now in use internationally.

  4. An accurate Rb density measurement method for a plasma wakefield accelerator experiment using a novel Rb reservoir

    NASA Astrophysics Data System (ADS)

    Öz, E.; Batsch, F.; Muggli, P.

    2016-09-01

    A method to accurately measure the density of Rb vapor is described. We plan on using this method for the Advanced Wakefield (AWAKE) (Assmann et al., 2014 [1]) project at CERN , which will be the world's first proton driven plasma wakefield experiment. The method is similar to the hook (Marlow, 1967 [2]) method and has been described in great detail in the work by Hill et al. (1986) [3]. In this method a cosine fit is applied to the interferogram to obtain a relative accuracy on the order of 1% for the vapor density-length product. A single-mode, fiber-based, Mach-Zenhder interferometer will be built and used near the ends of the 10 meter-long AWAKE plasma source to be able to make accurate relative density measurement between these two locations. This can then be used to infer the vapor density gradient along the AWAKE plasma source and also change it to the value desired for the plasma wakefield experiment. Here we describe the plan in detail and show preliminary results obtained using a prototype 8 cm long novel Rb vapor cell.

  5. Development of a Ground-Based Differential Absorption Lidar for High Accurate Measurements of Vertical CO2 Concentration Profiles

    NASA Astrophysics Data System (ADS)

    Nagasawa, Chikao; Abo, Makoto; Shibata, Yasukuni; Nagai, Tomohiro; Nakazato, Masahisa; Sakai, Tetsu; Tsukamoto, Makoto; Sakaizawa, Daisuku

    2010-05-01

    High-accurate vertical carbon dioxide (CO2) profiles are highly desirable in the inverse method to improve quantification and understanding of the global sink and source of CO2, and also global climate change. We have developed a ground based 1.6μm differential absorption lidar (DIAL) to achieve high accurate measurements of vertical CO2 profiles in the atmosphere. The DIAL system is constructed from the optical parametric oscillation(OPO) transmitter and the direct detection receiving system that included a near-infrared photomultiplier tube operating at photon counting mode. The primitive DIAL measurement was achieved successfully the vertical CO2 profile up to 7 km altitude with an error less than 1.0 % by integration time of 50 minutes and vertical resolution of 150m. We are developing the next generation 1.6 μm DIAL that can measure simultaneously the vertical CO2 concentration, temperature and pressure profiles in the atmosphere. The output laser of the OPO is 20mJ at a 500 Hz repetition rate and a 600mm diameter telescope is employed for this measurement. A very narrow interference filter (0.5nm FWHM) is used for daytime measurement. As the spectra of absorption lines of any molecules are influenced basically by the temperature and pressure in the atmosphere, it is important to measure them simultaneously so that the better accuracy of the DIAL measurement may be realized. Moreover, the value of the retrieved CO2 concentration will be improved remarkably by processing the iteration assignment of CO2 concentration, temperature and pressure, which measured by DIAL techniques. This work was financially supported by the Japan EOS Promotion Program by the MEXT Japan and System Development Program for Advanced Measurement and Analysis by the JST. Reference D. Sakaizawa, C. Nagasawa, T. Nagai, M. Abo, Y. Shibata, H. Nagai, M. Nakazato, and T. Sakai, Development of a 1.6μm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and

  6. Dipstick Spot urine pH does not accurately represent 24 hour urine PH measured by an electrode

    PubMed Central

    Omar, Mohamed; Sarkissian, Carl; Jianbo, Li; Calle, Juan; Monga, Manoj

    2016-01-01

    ABSTRACT Objectives To determine whether spot urine pH measured by dipstick is an accurate representation of 24 hours urine pH measured by an electrode. Materials and Methods We retrospectively reviewed urine pH results of patients who presented to the urology stone clinic. For each patient we recorded the most recent pH result measured by dipstick from a spot urine sample that preceded the result of a 24-hour urine pH measured by the use of a pH electrode. Patients were excluded if there was a change in medications or dietary recommendations or if the two samples were more than 4 months apart. A difference of more than 0.5 pH was considered an inaccurate result. Results A total 600 patients were retrospectively reviewed for the pH results. The mean difference in pH between spot urine value and the 24 hours collection values was 0.52±0.45 pH. Higher pH was associated with lower accuracy (p<0.001). The accuracy of spot urine samples to predict 24-hour pH values of <5.5 was 68.9%, 68.2% for 5.5 to 6.5 and 35% for >6.5. Samples taken more than 75 days apart had only 49% the accuracy of more recent samples (p<0.002). The overall accuracy is lower than 80% (p<0.001). Influence of diurnal variation was not significant (p=0.588). Conclusions Spot urine pH by dipstick is not an accurate method for evaluation of the patients with urolithiasis. Patients with alkaline urine are more prone to error with reliance on spot urine pH. PMID:27286119

  7. Can endocranial volume be estimated accurately from external skull measurements in great-tailed grackles (Quiscalus mexicanus)?

    PubMed Central

    Palmstrom, Christin R.

    2015-01-01

    There is an increasing need to validate and collect data approximating brain size on individuals in the field to understand what evolutionary factors drive brain size variation within and across species. We investigated whether we could accurately estimate endocranial volume (a proxy for brain size), as measured by computerized tomography (CT) scans, using external skull measurements and/or by filling skulls with beads and pouring them out into a graduated cylinder for male and female great-tailed grackles. We found that while females had higher correlations than males, estimations of endocranial volume from external skull measurements or beads did not tightly correlate with CT volumes. We found no accuracy in the ability of external skull measures to predict CT volumes because the prediction intervals for most data points overlapped extensively. We conclude that we are unable to detect individual differences in endocranial volume using external skull measurements. These results emphasize the importance of validating and explicitly quantifying the predictive accuracy of brain size proxies for each species and each sex. PMID:26082858

  8. Accurate human limb angle measurement: sensor fusion through Kalman, least mean squares and recursive least-squares adaptive filtering

    NASA Astrophysics Data System (ADS)

    Olivares, A.; Górriz, J. M.; Ramírez, J.; Olivares, G.

    2011-02-01

    Inertial sensors are widely used in human body motion monitoring systems since they permit us to determine the position of the subject's limbs. Limb angle measurement is carried out through the integration of the angular velocity measured by a rate sensor and the decomposition of the components of static gravity acceleration measured by an accelerometer. Different factors derived from the sensors' nature, such as the angle random walk and dynamic bias, lead to erroneous measurements. Dynamic bias effects can be reduced through the use of adaptive filtering based on sensor fusion concepts. Most existing published works use a Kalman filtering sensor fusion approach. Our aim is to perform a comparative study among different adaptive filters. Several least mean squares (LMS), recursive least squares (RLS) and Kalman filtering variations are tested for the purpose of finding the best method leading to a more accurate and robust limb angle measurement. A new angle wander compensation sensor fusion approach based on LMS and RLS filters has been developed.

  9. Combining computer algorithms with experimental approaches permits the rapid and accurate identification of T cell epitopes from defined antigens.

    PubMed

    Schirle, M; Weinschenk, T; Stevanović, S

    2001-11-01

    The identification of T cell epitopes from immunologically relevant antigens remains a critical step in the development of vaccines and methods for monitoring of T cell responses. This review presents an overview of strategies that employ computer algorithms for the selection of candidate peptides from defined proteins and subsequent verification of their in vivo relevance by experimental approaches. Several computer algorithms are currently being used for epitope prediction of various major histocompatibility complex (MHC) class I and II molecules, based either on the analysis of natural MHC ligands or on the binding properties of synthetic peptides. Moreover, the analysis of proteasomal digests of peptides and whole proteins has led to the development of algorithms for the prediction of proteasomal cleavages. In order to verify the generation of the predicted peptides during antigen processing in vivo as well as their immunogenic potential, several experimental approaches have been pursued in the recent past. Mass spectrometry-based bioanalytical approaches have been used specifically to detect predicted peptides among isolated natural ligands. Other strategies employ various methods for the stimulation of primary T cell responses against the predicted peptides and subsequent testing of the recognition pattern towards target cells that express the antigen.

  10. Accurate high-resolution measurements of 3-D tissue dynamics with registration-enhanced displacement encoded MRI.

    PubMed

    Gomez, Arnold D; Merchant, Samer S; Hsu, Edward W

    2014-06-01

    Displacement fields are important to analyze deformation, which is associated with functional and material tissue properties often used as indicators of health. Magnetic resonance imaging (MRI) techniques like DENSE and image registration methods like Hyperelastic Warping have been used to produce pixel-level deformation fields that are desirable in high-resolution analysis. However, DENSE can be complicated by challenges associated with image phase unwrapping, in particular offset determination. On the other hand, Hyperelastic Warping can be hampered by low local image contrast. The current work proposes a novel approach for measuring tissue displacement with both DENSE and Hyperelastic Warping, incorporating physically accurate displacements obtained by the latter to improve phase characterization in DENSE. The validity of the proposed technique is demonstrated using numerical and physical phantoms, and in vivo small animal cardiac MRI.

  11. Experimental Measurement of the Second-Order Coherence of Supercontinuum.

    PubMed

    Närhi, Mikko; Turunen, Jari; Friberg, Ari T; Genty, Goëry

    2016-06-17

    We measure experimentally the second-order coherence properties of supercontinuum generated in a photonic crystal fiber. Our approach is based on measuring separately the quasicoherent and quasistationary contributions to the cross-spectral density and mutual coherence functions using a combination of interferometric and nonlinear gating techniques. This allows us to introduce two-dimensional coherence spectrograms which provide a direct characterization and convenient visualization of the spectrotemporal coherence properties. The measured second-order coherence functions are in very good agreement with numerical simulations based on the generalized nonlinear Schrödinger equation. Our results pave the way towards the full experimental characterization of supercontinuum coherence properties. More generally, they provide a generic approach for the complete experimental measurement of the coherence of broadband sources.

  12. Experimental Measurement of the Second-Order Coherence of Supercontinuum

    NASA Astrophysics Data System (ADS)

    Närhi, Mikko; Turunen, Jari; Friberg, Ari T.; Genty, Goëry

    2016-06-01

    We measure experimentally the second-order coherence properties of supercontinuum generated in a photonic crystal fiber. Our approach is based on measuring separately the quasicoherent and quasistationary contributions to the cross-spectral density and mutual coherence functions using a combination of interferometric and nonlinear gating techniques. This allows us to introduce two-dimensional coherence spectrograms which provide a direct characterization and convenient visualization of the spectrotemporal coherence properties. The measured second-order coherence functions are in very good agreement with numerical simulations based on the generalized nonlinear Schrödinger equation. Our results pave the way towards the full experimental characterization of supercontinuum coherence properties. More generally, they provide a generic approach for the complete experimental measurement of the coherence of broadband sources.

  13. Hyperspectral imaging-based spatially-resolved technique for accurate measurement of the optical properties of horticultural products

    NASA Astrophysics Data System (ADS)

    Cen, Haiyan

    Hyperspectral imaging-based spatially-resolved technique is promising for determining the optical properties and quality attributes of horticultural and food products. However, considerable challenges still exist for accurate determination of spectral absorption and scattering properties from intact horticultural products. The objective of this research was, therefore, to develop and optimize hyperspectral imaging-based spatially-resolved technique for accurate measurement of the optical properties of horticultural products. Monte Carlo simulations and experiments for model samples of known optical properties were performed to optimize the inverse algorithm of a single-layer diffusion model and the optical designs, for extracting the absorption (micro a) and reduced scattering (micros') coefficients from spatially-resolved reflectance profiles. The logarithm and integral data transformation and the relative weighting methods were found to greatly improve the parameter estimation accuracy with the relative errors of 10.4%, 10.7%, and 11.4% for micro a, and 6.6%, 7.0%, and 7.1% for micros', respectively. More accurate measurements of optical properties were obtained when the light beam was of Gaussian type with the diameter of less than 1 mm, and the minimum and maximum source-detector distances were 1.5 mm and 10--20 transport mean free paths, respectively. An optical property measuring prototype was built, based on the optimization results, and evaluated for automatic measurement of absorption and reduced scattering coefficients for the wavelengths of 500--1,000 nm. The instrument was used to measure the optical properties, and assess quality/maturity, of 500 'Redstar' peaches and 1039 'Golden Delicious' (GD) and 1040 'Delicious' (RD) apples. A separate study was also conducted on confocal laser scanning and scanning electron microscopic image analysis and compression test of fruit tissue specimens to measure the structural and mechanical properties of 'Golden

  14. Necessary Conditions for Accurate, Transient Hot-Wire Measurements of the Apparent Thermal Conductivity of Nanofluids are Seldom Satisfied

    NASA Astrophysics Data System (ADS)

    Antoniadis, Konstantinos D.; Tertsinidou, Georgia J.; Assael, Marc J.; Wakeham, William A.

    2016-08-01

    The paper considers the conditions that are necessary to secure accurate measurement of the apparent thermal conductivity of two-phase systems comprising nanoscale particles of one material suspended in a fluid phase of a different material. It is shown that instruments operating according to the transient hot-wire technique can, indeed, produce excellent measurements when a finite element method (FEM) is employed to describe the instrument for the exact geometry of the hot wire. Furthermore, it is shown that an approximate analytic solution can be employed with equal success, over the time range of 0.1 s to 1 s, provided that (a) two wires are employed, so that end effects are canceled, (b) each wire is very thin, less than 30 \\upmu m diameter, so that the line source model and the corresponding corrections are valid, (c) low values of the temperature rise, less than 4 K, are employed in order to minimize the effect of convection on the heat transfer in the time of measurement of 1 s, and (d) insulated wires are employed for measurements in electrically conducting or polar liquids to avoid current leakage or other electrical distortions. According to these criteria, a transient hot-wire instrument has been designed, constructed, and employed for the measurement of the enhancement of the thermal conductivity of water when TiO2 or multi-wall carbon nanotubes (MWCNT) are added. These new results, together with a critical evaluation of other measurements, demonstrate the importance of proper implementation of the technique.

  15. Chamber for indirect calorimetry with accurate measurement and time discrimination of metabolic plateaus of over 20 min.

    PubMed

    Nguyen, T; de Jonge, L; Smith, S R; Bray, G A

    2003-09-01

    A robust algorithm for pull-calorimeters that provides a rapid response to changes in respiratory gas exchange has been implemented. Metabolic plateaus (over 20 min), such as that generated by steady treadmill exercise, can be measured accurately (< 2.0% error for an energy expenditure level of 16.7 kJ min(-1)). The time resolution for changes between plateaus can be accurately found with 1 min discrimination. Implementation required only software changes but no structural or instrumentation changes to the chamber. The algorithm was based on the one developed for the push-calorimeter at the Sahlgrenska Hospital in Sweden. The method utilises published equations for the rate of O2 consumption and CO2 production in the chamber, along with techniques for suppressing noise and identifying trends. Using the exact solution of the equations for steady state, the O2 concentrations from the preceding 30 min period are fitted to two connected exponential segments, of variable length, using the least-squares method. The smoothed O2 concentration and associated time derivative are then determined for the time point 15 min earlier and substituted into the respiration equations. The CO2 concentrations are subjected to the same analysis. The process is repeated every minute, and the newly computed rates of O2 consumption and CO2 production, as well as metabolic rate, are then presented. Gas injection tests proved that the chamber can respond instantaneously to a change from one steady state of respiration to another and correctly averages repeated changes in respiration with periods less than 15min (< 1.4% error for simulated, alternating O2 consumption levels of 0.81 min (-1) and 0.01 min). The successful integration of the algorithm into the Pennington chambers allows for traditional 24 h energy expenditure measurements and various metabolic experiments requiring rapid responses.

  16. How accurate are antenatal weight measurements? A survey of hospital and community clinics in a South Thames Region NHS Trust.

    PubMed

    Harris, H E; Ellison, G T; Holliday, M; Nickson, C

    1998-04-01

    The accuracy of antenatal weight data recorded in obstetric notes was investigated in the 45 hospital and community antenatal clinics within a South Thames Region NHS Trust. In order to assess the reliability and validity of all 60 clinic scales triplicate measurements of body weight for low- and high-weight subjects were recorded on each clinical scale and on a calibrated standard scale. The quality of weighing practice during antenatal care was investigated by means of semi-structured interviews conducted with all 33 midwives who currently provide antenatal care within the Trust. Beam balances had the highest reliability and validity, whereas scales with spring mechanisms were the least accurate. Only 40% of the clinics surveyed had access to beam balances, yet most of the maternal weight measurements recorded during antenatal care are likely to be out by no more than 1-1.5% of body weight. Weighing practice was generally inconsistent, and serial measurements of maternal body weight collected during pregnancy are probably too imprecise to provide a sensitive screen for conditions associated with unusual weight gain and too inaccurate to assess compliance with guidelines for weight gain.

  17. Accurate Measurements of Multiple-Bond 13C- 1H Coupling Constants from Phase-Sensitive 2D INEPT Spectra

    NASA Astrophysics Data System (ADS)

    Ding, Keyang

    1999-10-01

    Measurements of multiple-bond 13C-1H coupling constants are of great interest for the assignment of nonprotonated 13C resonances and the elucidation of molecular conformation in solution. Usually, the heteronuclear multiple-bond coupling constants were measured either by the JCH splittings mostly in selective 2D spectra or in 3D spectra, which are time consuming, or by the cross peak intensity analysis in 2D quantitative heteronuclear J correlation spectra (1994, G. Zhu, A. Renwick, and A. Bax, J. Magn. Reson. A 110, 257; 1994, A. Bax, G. W. Vuister, S. Grzesiek, F. Delaglio, A. C. Wang, R. Tschudin, and G. Zhu, Methods Enzymol. 239, 79.), which suffer from the accuracy problem caused by the signal-to-noise ratio and the nonpure absorptive peak patterns. Concerted incrementation of the duration for developing proton antiphase magnetization with respect to carbon-13 and the evolution time for proton chemical shift in different steps in a modified INEPT pulse sequence provides a new method for accurate measurements of heteronuclear multiple-bond coupling constants in a single 2D experiment.

  18. A portable analog lock-in amplifier for accurate phase measurement and application in high-precision optical oxygen concentration detection

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Chang, Jun; Wang, Fupeng; Wang, Zongliang; Wei, Wei; Liu, Yuanyuan; Qin, Zengguang

    2017-03-01

    A portable analog lock-in amplifier capable of accurate phase detection is proposed in this paper. The proposed lock-in amplifier, which uses the dual-channel orthometric signals as the references to build the xy coordinate system, can detect the relative phase between the input and x-axis based on trigonometric function. The sensitivity of the phase measurement reaches 0.014 degree, and a detection precision of 0.1 degree is achieved. At the same time, the performance of the lock-in amplifier is verified in the high precision optical oxygen concentration detection. Experimental results reveal that the portable analog lock-in amplifier is accurate for phase detection applications. In the oxygen sensing experiments, 0.058% oxygen concentration resulted in 0.1 degree phase shift detected by the lock-in amplifier precisely. In addition, the lock-in amplifier is small and economical compared with the commercial lock-in equipments, so it can be easily integrated in many portable devices for industrial applications.

  19. A portable analog lock-in amplifier for accurate phase measurement and application in high-precision optical oxygen concentration detection

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Chang, Jun; Wang, Fupeng; Wang, Zongliang; Wei, Wei; Liu, Yuanyuan; Qin, Zengguang

    2016-10-01

    A portable analog lock-in amplifier capable of accurate phase detection is proposed in this paper. The proposed lock-in amplifier, which uses the dual-channel orthometric signals as the references to build the xy coordinate system, can detect the relative phase between the input and x-axis based on trigonometric function. The sensitivity of the phase measurement reaches 0.014 degree, and a detection precision of 0.1 degree is achieved. At the same time, the performance of the lock-in amplifier is verified in the high precision optical oxygen concentration detection. Experimental results reveal that the portable analog lock-in amplifier is accurate for phase detection applications. In the oxygen sensing experiments, 0.058% oxygen concentration resulted in 0.1 degree phase shift detected by the lock-in amplifier precisely. In addition, the lock-in amplifier is small and economical compared with the commercial lock-in equipments, so it can be easily integrated in many portable devices for industrial applications.

  20. Accurate and precise plasma clearance measurement using four 99mTc-DTPA plasma samples over 4 h

    PubMed Central

    Wanasundara, Surajith N.; Wesolowski, Michal J.; Barnfield, Mark C.; Waller, Michael L.; Murray, Anthony W.; Burniston, Maria T.; Babyn, Paul S.

    2016-01-01

    Objectives Glomerular filtration rate can be measured as the plasma clearance (CL) of a glomerular filtration rate marker despite body fluid disturbances using numerous, prolonged time samples. We desire a simplified technique without compromised accuracy and precision. Materials and methods We compared CL values derived from two plasma concentration curve area methods – (a) biexponential fitting [CL (E2)] and (b) Tikhonov adaptively regularized gamma variate fitting [CL (Tk-GV)] – for 4 versus 8 h time samplings from 412 99mTc-DTPA studies in 142 patients, mostly paediatric patients, with suspected fluid disturbances. Results CL (Tk-GV) from four samples/4 h and from nine samples/8 h, both accurately and precisely agreed with the standard, which was taken to be nine samples/8 h CL from (noncompartmental) numerical integration [CL (NI)]. The E2 method, four samples/4 h, and nine samples/8 h median CL values significantly overestimated the CL (NI) values by 4.9 and 3.8%, respectively. Conclusion Compared with the standard, CL (E2) from four samples/4 h and from nine samples/8 h proved to be the most inaccurate and imprecise method examined, and can be replaced by better methods for calculating CL. The CL (Tk-GV) can be used to reduce sampling time in half from 8 to 4 h and from nine to four samples for a precise and accurate, yet more easily tolerated and simplified test. PMID:26465802

  1. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2003-04-01

    This report summarizes technical progress over the first six months of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on analyzing and testing factors that impact performance degradation of the initially designed sensor prototype, including sensing element movement within the sensing probe and optical signal quality degradation. Based these results, a new version of the sensing system was designed by combining the sapphire disk sensing element and the single crystal zirconia right angle light reflector into one novel single crystal sapphire right angle prism. The new sensor prototype was tested up to 1650 C.

  2. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang; Zhengyu Huang

    2004-04-01

    This report summarizes technical progress over the third six month period of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on sensor probe design and machining, sensor electronics design, software algorithm design, sensor field installation procedures, and sensor remote data access and control. Field testing will begin in the next several weeks.

  3. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2005-11-01

    This report summarizes technical progress April-September 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report. The sensing system will be installed and tested at TECO's Polk Power Station. Following a site visit in June 2005, our efforts have been focused on preparing for that field test, including he design of the sensor mechanical packaging, sensor electronics, the data transfer module, and the necessary software codes to accommodate this application.. We are currently ready to start sensor fabrication.

  4. A modified ELISA accurately measures secretion of high molecular weight hyaluronan (HA) by Graves' disease orbital cells.

    PubMed

    Krieger, Christine C; Gershengorn, Marvin C

    2014-02-01

    Excess production of hyaluronan (hyaluronic acid [HA]) in the retro-orbital space is a major component of Graves' ophthalmopathy, and regulation of HA production by orbital cells is a major research area. In most previous studies, HA was measured by ELISAs that used HA-binding proteins for detection and rooster comb HA as standards. We show that the binding efficiency of HA-binding protein in the ELISA is a function of HA polymer size. Using gel electrophoresis, we show that HA secreted from orbital cells is primarily comprised of polymers more than 500 000. We modified a commercially available ELISA by using 1 million molecular weight HA as standard to accurately measure HA of this size. We demonstrated that IL-1β-stimulated HA secretion is at least 2-fold greater than previously reported, and activation of the TSH receptor by an activating antibody M22 from a patient with Graves' disease led to more than 3-fold increase in HA production in both fibroblasts/preadipocytes and adipocytes. These effects were not consistently detected with the commercial ELISA using rooster comb HA as standard and suggest that fibroblasts/preadipocytes may play a more prominent role in HA remodeling in Graves' ophthalmopathy than previously appreciated.

  5. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect

    Kristie Cooper; Anbo Wang

    2007-03-31

    This report summarizes technical progress October 2006 - March 2007 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. During the second phase, an alternative high temperature sensing system based on Fabry-Perot interferometry was developed that offers a number of advantages over the BPDI solution. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. The sapphire wafer-based interferometric sensing system that was installed at TECO's Polk Power Station remained in operation for seven months. Our efforts have been focused on monitoring and analyzing the real-time data collected, and preparing for a second field test.

  6. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2003-11-01

    This report summarizes technical progress over the second six month period of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on evaluating corrosion effects in single crystal sapphire at temperatures up to 1400 C, and designing the sensor mechanical packaging with input from Wabash River Power Plant. Upcoming meetings will establish details for the gasifier field test.

  7. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang; Zhengyu Huang; Yizheng Zhu

    2005-04-01

    This report summarizes technical progress October 2004-March 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report.

  8. Development of an accurate EPID-based output measurement and dosimetric verification tool for electron beam therapy

    PubMed Central

    Ding, Aiping; Xing, Lei; Han, Bin

    2015-01-01

    chamber measurements. The average discrepancy between EPID and ion chamber/film measurements was 0.81% ± 0.60% (SD) and 1.34% ± 0.75%, respectively. For the three clinical cases, the difference in output between the EPID- and ion chamber array measured values was found to be 1.13% ± 0.11%, 0.54% ± 0.10%, and 0.74% ± 0.11%, respectively. Furthermore, the γ-index analysis showed an excellent agreement between the EPID- and ion chamber array measured dose distributions: 100% of the pixels passed the criteria of 3%/3 mm. When the γ-index was set to be 2%/2 mm, the pass rate was found to be 99.0% ± 0.07%, 98.2% ± 0.14%, and 100% for the three cases. Conclusions: The EPID dosimetry system developed in this work provides an accurate and reliable tool for routine output measurement and dosimetric verification of electron beam therapy. Coupled with its portability and ease of use, the proposed system promises to replace the current film-based approach for fast and reliable assessment of small and irregular electron field dosimetry. PMID:26133618

  9. A rapid and accurate method, ventilated chamber C-history method, of measuring the emission characteristic parameters of formaldehyde/VOCs in building materials.

    PubMed

    Huang, Shaodan; Xiong, Jianyin; Zhang, Yinping

    2013-10-15

    The indoor pollution caused by formaldehyde and volatile organic compounds (VOCs) emitted from building materials poses an adverse effect on people's health. It is necessary to understand and control the behaviors of the emission sources. Based on detailed mass transfer analysis on the emission process in a ventilated chamber, this paper proposes a novel method of measuring the three emission characteristic parameters, i.e., the initial emittable concentration, the diffusion coefficient and the partition coefficient. A linear correlation between the logarithm of dimensionless concentration and time is derived. The three parameters can then be calculated from the intercept and slope of the correlation. Compared with the closed chamber C-history method, the test is performed under ventilated condition thus some commonly-used measurement instruments (e.g., GC/MS, HPLC) can be applied. While compared with other methods, the present method can rapidly and accurately measure the three parameters, with experimental time less than 12h and R(2) ranging from 0.96 to 0.99 for the cases studied. Independent experiment was carried out to validate the developed method, and good agreement was observed between the simulations based on the determined parameters and experiments. The present method should prove useful for quick characterization of formaldehyde/VOC emissions from indoor materials.

  10. An accurate measurement of the baryonic Tully-Fisher relation with heavily gas-dominated ALFALFA galaxies

    NASA Astrophysics Data System (ADS)

    Papastergis, E.; Adams, E. A. K.; van der Hulst, J. M.

    2016-09-01

    We use a sample of 97 galaxies selected from the Arecibo legacy fast ALFA (ALFALFA) 21 cm survey to make an accurate measurement of the baryonic Tully-Fisher relation (BTFR). These galaxies are specifically selected to be heavily gas-dominated (Mgas/M∗ ≳ 2.7) and to be oriented edge-on. The former property ensures that the error on the galactic baryonic mass is small, despite the large systematic uncertainty involved in galactic stellar mass estimates. The latter property means that rotational velocities can be derived directly from the width of the 21 cm emission line, without any need for inclination corrections. We measure a slope for the linewidth-based BTFR of α = 3.75 ± 0.11, a value that is somewhat steeper than (but in broad agreement with) previous literature results. The relation is remarkably tight, with almost all galaxies being located within a perpendicular distance of ± 0.1 dex from the best fit line. The low observational error budget for our sample enables us to establish that, despite its tightness, the measured linewidth-based BTFR has some small (i.e., non-zero) intrinsic scatter. We furthermore find a systematic difference in the BTFR of galaxies with "double-horned" 21 cm line profiles - suggestive of flat outer galactic rotation curves - and those with "peaked" profiles - suggestive of rising rotation curves. When we restrict our sample of galaxies to objects in the former category, we measure a slightly steeper slope of α = 4.13 ± 0.15. Overall, the high-accuracy measurement of the BTFR presented in this article is intended as a reliable observational benchmark against which to test theoretical expectations. Here we consider a representative set of semi-analytic models and hydrodynamic simulations in the lambda cold dark matter (ΛCDM) context, as well as modified Newtonian dynamics (MOND). In the near future, interferometric follow-up observations of several sample members will enable us to further refine the BTFR measurement, and

  11. A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements.

    PubMed

    Weaver, Phoebe G; Jagow, Devin M; Portune, Cameron M; Kenney, John W

    2016-07-19

    The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and a CCD spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, fast sample freezing, fast alignment of the sample, accurate and stable sample temperatures, and small size and portability of the Dewar/cryostat cryogenic unit. When coupled with the fast data acquisition rates of the CCD spectrograph, this Dewar/cryostat is capable of supporting cryogenic luminescence spectroscopic measurements on luminescent samples at a series of known, stable temperatures in the 77-300 K range. A temperature-dependent study of the oxygen quenching of luminescence in a rhodium(III) transition metal complex is presented as an example of the type of investigation possible with this Dewar/cryostat. In the context of this apparatus, a stable temperature for cryogenic spectroscopy means a luminescent sample that is thermally equilibrated with either liquid nitrogen or gaseous nitrogen at a known measureable temperature that does not vary (ΔT < 0.1 K) during the short time scale (~1-10 sec) of the spectroscopic measurement by the CCD. The Dewar/cryostat works by taking advantage of the positive thermal gradient dT/dh that develops above liquid nitrogen level in the Dewar where h is the height of the sample above the liquid nitrogen level. The slow evaporation of the liquid nitrogen results in a slow increase in h over several hours and a consequent slow increase in the sample temperature T over this time period. A quickly acquired luminescence spectrum effectively catches the sample at a constant, thermally equilibrated temperature.

  12. Experimental Validation of Simulations Using Full-field Measurement Techniques

    SciTech Connect

    Hack, Erwin

    2010-05-28

    The calibration by reference materials of dynamic full-field measurement systems is discussed together with their use to validate numerical simulations of structural mechanics. The discussion addresses three challenges that are faced in these processes, i.e. how to calibrate a measuring instrument that (i) provides full-field data, and (ii) is dynamic; (iii) how to compare data from simulation and experimentation.

  13. Characterization of condenser microphones under different environmental conditions for accurate speed of sound measurements with acoustic resonators.

    PubMed

    Guianvarc'h, Cécile; Gavioso, Roberto M; Benedetto, Giuliana; Pitre, Laurent; Bruneau, Michel

    2009-07-01

    Condenser microphones are more commonly used and have been extensively modeled and characterized in air at ambient temperature and static pressure. However, several applications of interest for metrology and physical acoustics require to use these transducers in significantly different environmental conditions. Particularly, the extremely accurate determination of the speed of sound in monoatomic gases, which is pursued for a determination of the Boltzmann constant k by an acoustic method, entails the use of condenser microphones mounted within a spherical cavity, over a wide range of static pressures, at the temperature of the triple point of water (273.16 K). To further increase the accuracy achievable in this application, the microphone frequency response and its acoustic input impedance need to be precisely determined over the same static pressure and temperature range. Few previous works examined the influence of static pressure, temperature, and gas composition on the microphone's sensitivity. In this work, the results of relative calibrations of 1/4 in. condenser microphones obtained using an electrostatic actuator technique are presented. The calibrations are performed in pure helium and argon gas at temperatures near 273 K and in the pressure range between 10 and 600 kPa. These experimental results are compared with the predictions of a realistic model available in the literature, finding a remarkable good agreement. The model provides an estimate of the acoustic impedance of 1/4 in. condenser microphones as a function of frequency and static pressure and is used to calculate the corresponding frequency perturbations induced on the normal modes of a spherical cavity when this is filled with helium or argon gas.

  14. Characterization of condenser microphones under different environmental conditions for accurate speed of sound measurements with acoustic resonators

    SciTech Connect

    Guianvarc'h, Cecile; Pitre, Laurent; Bruneau, Michel

    2009-07-15

    Condenser microphones are more commonly used and have been extensively modeled and characterized in air at ambient temperature and static pressure. However, several applications of interest for metrology and physical acoustics require to use these transducers in significantly different environmental conditions. Particularly, the extremely accurate determination of the speed of sound in monoatomic gases, which is pursued for a determination of the Boltzmann constant k by an acoustic method, entails the use of condenser microphones mounted within a spherical cavity, over a wide range of static pressures, at the temperature of the triple point of water (273.16 K). To further increase the accuracy achievable in this application, the microphone frequency response and its acoustic input impedance need to be precisely determined over the same static pressure and temperature range. Few previous works examined the influence of static pressure, temperature, and gas composition on the microphone's sensitivity. In this work, the results of relative calibrations of 1/4 in. condenser microphones obtained using an electrostatic actuator technique are presented. The calibrations are performed in pure helium and argon gas at temperatures near 273 K and in the pressure range between 10 and 600 kPa. These experimental results are compared with the predictions of a realistic model available in the literature, finding a remarkable good agreement. The model provides an estimate of the acoustic impedance of 1/4 in. condenser microphones as a function of frequency and static pressure and is used to calculate the corresponding frequency perturbations induced on the normal modes of a spherical cavity when this is filled with helium or argon gas.

  15. SU-F-BRF-13: Investigating the Feasibility of Accurate Dose Measurement in a Deforming Radiochromic Dosimeter

    SciTech Connect

    Juang, T; Adamovics, J; Oldham, M

    2014-06-15

    Purpose: Presage-Def, a deformable radiochromic 3D dosimeter, has been previously shown to have potential for validating deformable image registration algorithms. This work extends this effort to investigate the feasibility of using Presage-Def to validate dose-accumulation algorithms in deforming structures. Methods: Two cylindrical Presage-Def dosimeters (8cm diameter, 4.5cm length) were irradiated in a water-bath with a simple 4-field box treatment. Isocentric dose was 20Gy. One dosimeter served as control (no deformation) while the other was laterally compressed during irradiation by 21%. Both dosimeters were imaged before and after irradiation with a fast (∼10 minutes for 1mm isotropic resolution), broad beam, high resolution optical-CT scanner. Measured dose distributions were compared to corresponding distributions calculated by a commissioned Eclipse planning system. Accuracy in the control was evaluated with 3D gamma (3%/3mm). The dose distribution calculated for the compressed dosimeter in the irradiation geometry cannot be directly compared via profiles or 3D gamma to the measured distribution, which deforms with release from compression. Thus, accuracy under deformation was determined by comparing integral dose within the high dose region of the deformed dosimeter distribution versus calculated dose. Dose profiles were used to study temporal stability of measured dose distributions. Results: Good dose agreement was demonstrated in the control with a 3D gamma passing rate of 96.6%. For the dosimeter irradiated under compression, the measured integral dose in the high dose region (518.0Gy*cm3) was within 6% of the Eclipse-calculated integral dose (549.4Gy*cm3). Elevated signal was noted on the dosimeter edge in the direction of compression. Change in dosimeter signal over 1.5 hours was ≤2.7%, and the relative dose distribution remained stable over this period of time. Conclusion: Presage-Def is promising as a 3D dosimeter capable of accurately

  16. Accurate modeling of fluorescence line narrowing difference spectra: Direct measurement of the single-site fluorescence spectrum

    NASA Astrophysics Data System (ADS)

    Reppert, Mike; Naibo, Virginia; Jankowiak, Ryszard

    2010-07-01

    Accurate lineshape functions for modeling fluorescence line narrowing (FLN) difference spectra (ΔFLN spectra) in the low-fluence limit are derived and examined in terms of the physical interpretation of various contributions, including photoproduct absorption and emission. While in agreement with the earlier results of Jaaniso [Proc. Est. Acad. Sci., Phys., Math. 34, 277 (1985)] and Fünfschilling et al. [J. Lumin. 36, 85 (1986)], the derived formulas differ substantially from functions used recently [e.g., M. Rätsep et al., Chem. Phys. Lett. 479, 140 (2009)] to model ΔFLN spectra. In contrast to traditional FLN spectra, it is demonstrated that for most physically reasonable parameters, the ΔFLN spectrum reduces simply to the single-site fluorescence lineshape function. These results imply that direct measurement of a bulk-averaged single-site fluorescence lineshape function can be accomplished with no complicated extraction process or knowledge of any additional parameters such as site distribution function shape and width. We argue that previous analysis of ΔFLN spectra obtained for many photosynthetic complexes led to strong artificial lowering of apparent electron-phonon coupling strength, especially on the high-energy side of the pigment site distribution function.

  17. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis.

    PubMed

    Ruiz de Gauna, Sofía; González-Otero, Digna M; Ruiz, Jesus; Gutiérrez, J J; Russell, James K

    2016-01-01

    Background. Cardiopulmonary resuscitation (CPR) feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin's back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%). Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p < 0.001). Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p < 0.001). Median error in rate was 0.9 cpm (1.0%), with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces.

  18. Accurate quantification of creatinine in serum by coupling a measurement standard to extractive electrospray ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Huang, Keke; Li, Ming; Li, Hongmei; Li, Mengwan; Jiang, You; Fang, Xiang

    2016-01-01

    Ambient ionization (AI) techniques have been widely used in chemistry, medicine, material science, environmental science, forensic science. AI takes advantage of direct desorption/ionization of chemicals in raw samples under ambient environmental conditions with minimal or no sample preparation. However, its quantitative accuracy is restricted by matrix effects during the ionization process. To improve the quantitative accuracy of AI, a matrix reference material, which is a particular form of measurement standard, was coupled to an AI technique in this study. Consequently the analyte concentration in a complex matrix can be easily quantified with high accuracy. As a demonstration, this novel method was applied for the accurate quantification of creatinine in serum by using extractive electrospray ionization (EESI) mass spectrometry. Over the concentration range investigated (0.166 ~ 1.617 μg/mL), a calibration curve was obtained with a satisfactory linearity (R2 = 0.994), and acceptable relative standard deviations (RSD) of 4.6 ~ 8.0% (n = 6). Finally, the creatinine concentration value of a serum sample was determined to be 36.18 ± 1.08 μg/mL, which is in excellent agreement with the certified value of 35.16 ± 0.39 μg/mL.

  19. An accurate method to measure alpha-emitting natural radionuclides in atmospheric filters: Application in two NORM industries

    NASA Astrophysics Data System (ADS)

    Lozano, R. L.; Bolívar, J. P.; San Miguel, E. G.; García-Tenorio, R.; Gázquez, M. J.

    2011-12-01

    In this work, an accurate method for the measurement of natural alpha-emitting radionuclides from aerosols collected in air filters is presented and discussed in detail. The knowledge of the levels of several natural alpha-emitting radionuclides (238U, 234U, 232Th, 230Th, 228Th, 226Ra and 210Po) in atmospheric aerosols is essential not only for a better understanding of the several atmospheric processes and changes, but also for a proper evaluation of the potential doses, which can inadvertently be received by the population via inhalation. The proposed method takes into account the presence of intrinsic amounts of these radionuclides in the matrices of the quartz filters used, as well as the possible variation in the humidity of the filters throughout the collection process. In both cases, the corrections necessary in order to redress these levels have been evaluated and parameterized. Furthermore, a detailed study has been performed into the optimisation of the volume of air to be sampled in order to increase the accuracy in the determination of the radionuclides. The method as a whole has been applied for the determination of the activity concentrations of U- and Th-isotopes in aerosols collected at two NORM (Naturally Occurring Radioactive Material) industries located in the southwest of Spain. Based on the levels found, a conservative estimation has been performed to yield the additional committed effective doses to which the workers are potentially susceptible due to inhalation of anthropogenic material present in the environment of these two NORM industries.

  20. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis

    PubMed Central

    Gutiérrez, J. J.; Russell, James K.

    2016-01-01

    Background. Cardiopulmonary resuscitation (CPR) feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin's back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%). Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p < 0.001). Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p < 0.001). Median error in rate was 0.9 cpm (1.0%), with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces. PMID:27999808

  1. Assignment of resonances in dissociative recombination of HD{sup +} ions: High-resolution measurements compared with accurate computations

    SciTech Connect

    Waffeu Tamo, F. O.; Buhr, H.; Schwalm, D.; Motapon, O.; Altevogt, S.; Andrianarijaona, V. M.; Grieser, M.; Lammich, L.; Lestinsky, M.; Motsch, M.; Novotny, S.; Orlov, D. A.; Pedersen, H. B.; Sprenger, F.; Weigel, U.; Wolf, A.; Nevo, I.; Urbain, X.; Schneider, I. F.

    2011-08-15

    The collision-energy resolved rate coefficient for dissociative recombination of HD{sup +} ions in the vibrational ground state is measured using the photocathode electron target at the heavy-ion storage ring TSR. Rydberg resonances associated with rovibrational excitation of the HD{sup +} core are scanned as a function of the electron collision energy with an instrumental broadening below 1 meV in the low-energy limit. The measurement is compared to calculations using multichannel quantum defect theory, accounting for rotational structure and interactions and considering the six lowest rotational energy levels as initial ionic states. Using thermal-equilibrium-level populations at 300 K to approximate the experimental conditions, close correspondence between calculated and measured structures is found up to the first vibrational excitation threshold of the cations near 0.24 eV. Detailed assignments, including naturally broadened and overlapping Rydberg resonances, are performed for all structures up to 0.024 eV. Resonances from purely rotational excitation of the ion core are found to have similar strengths as those involving vibrational excitation. A dominant low-energy resonance is assigned to contributions from excited rotational states only. The results indicate strong modifications in the energy dependence of the dissociative recombination rate coefficient through the rotational excitation of the parent ions, and underline the need for studies with rotationally cold species to obtain results reflecting low-temperature ionized media.

  2. The application of intraoperative transit time flow measurement to accurately assess anastomotic quality in sequential vein grafting

    PubMed Central

    Yu, Yang; Zhang, Fan; Gao, Ming-Xin; Li, Hai-Tao; Li, Jing-Xing; Song, Wei; Huang, Xin-Sheng; Gu, Cheng-Xiong

    2013-01-01

    OBJECTIVES Intraoperative transit time flow measurement (TTFM) is widely used to assess anastomotic quality in coronary artery bypass grafting (CABG). However, in sequential vein grafting, the flow characteristics collected by the conventional TTFM method are usually associated with total graft flow and might not accurately indicate the quality of every distal anastomosis in a sequential graft. The purpose of our study was to examine a new TTFM method that could assess the quality of each distal anastomosis in a sequential graft more reliably than the conventional TTFM approach. METHODS Two TTFM methods were tested in 84 patients who underwent sequential saphenous off-pump CABG in Beijing An Zhen Hospital between April and August 2012. In the conventional TTFM method, normal blood flow in the sequential graft was maintained during the measurement, and the flow probe was placed a few centimetres above the anastomosis to be evaluated. In the new method, blood flow in the sequential graft was temporarily reduced during the measurement by placing an atraumatic bulldog clamp at the graft a few centimetres distal to the anastomosis to be evaluated, while the position of the flow probe remained the same as in the conventional method. This new TTFM method was named the flow reduction TTFM. Graft flow parameters measured by both methods were compared. RESULTS Compared with the conventional TTFM, the flow reduction TTFM resulted in significantly lower mean graft blood flow (P < 0.05); in contrast, yielded significantly higher pulsatility index (P < 0.05). Diastolic filling was not significantly different between the two methods and was >50% in both cases. Interestingly, the flow reduction TTFM identified two defective middle distal anastomoses that the conventional TTFM failed to detect. Graft flows near the defective distal anastomoses were improved substantially after revision. CONCLUSIONS In this study, we found that temporary reduction of graft flow during TTFM seemed to

  3. Highly accurate nuclear and electronic stopping cross sections derived using Monte Carlo simulations to reproduce measured range data

    NASA Astrophysics Data System (ADS)

    Wittmaack, Klaus; Mutzke, Andreas

    2017-03-01

    We have examined and confirmed the previously unexplored concept of using Monte Carlo calculations in combination with measured projected ranges of ions implanted in solids to derive a quantitative description of nuclear interaction and electronic stopping. The study involved 98 ranges of 11B in Si between 1 keV and 8 MeV, contained in 12 sets of 10 different groups. Systematic errors by up to ±8% were removed to establish a refined data base with 93 ranges featuring only statistical uncertainties (±1.8%). The Monte Carlo calculations could be set up to reproduce the refined ranges with a mean ratio 1.002 ± 1.7%. The input parameters required for this very high level of agreement are as follows. Nuclear interaction is best described by the Kr-C potential, but in obligatory combination with the Lindhard-Scharff (LS) screening length. Up to 300 keV, the electronic stopping cross section is proportional to the projectile velocity, Se = kSe,LS, with k = 1.46 ± 0.01. At higher energies, Se falls progressively short of kSe,LS. Around the Bragg peak, i.e., between 0.8 and 10 MeV, Se is modeled by an adjustable function serving to tailor the peak shape properly. Calculated and measured isotope effects for ranges of 10B and 11B in Si agree within the experimental uncertainty (±0.25%). The range-based Se,R(E) reported here predicts the scarce experimental data derived from the energy loss in projectile transmission through thin Si foils to within 2% or better. By contrast, Se(E) data of available stopping power tables exhibit deviations from Se,R(E) between -40% and +14%.

  4. Electrosurgical vessel sealing tissue temperature: experimental measurement and finite element modeling.

    PubMed

    Chen, Roland K; Chastagner, Matthew W; Dodde, Robert E; Shih, Albert J

    2013-02-01

    The temporal and spatial tissue temperature profile in electrosurgical vessel sealing was experimentally measured and modeled using finite element modeling (FEM). Vessel sealing procedures are often performed near the neurovascular bundle and may cause collateral neural thermal damage. Therefore, the heat generated during electrosurgical vessel sealing is of concern among surgeons. Tissue temperature in an in vivo porcine femoral artery sealed using a bipolar electrosurgical device was studied. Three FEM techniques were incorporated to model the tissue evaporation, water loss, and fusion by manipulating the specific heat, electrical conductivity, and electrical contact resistance, respectively. These three techniques enable the FEM to accurately predict the vessel sealing tissue temperature profile. The averaged discrepancy between the experimentally measured temperature and the FEM predicted temperature at three thermistor locations is less than 7%. The maximum error is 23.9%. Effects of the three FEM techniques are also quantified.

  5. A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements

    NASA Astrophysics Data System (ADS)

    Chisham, G.; Freeman, M. P.

    2003-04-01

    Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the SuperDARN HF radars have been previously used for locating and tracking the PCB in the cusp region. The boundary is generally observed in meridional beams of the SuperDARN radars and appears as a distinct change between low spectral width values observed equatorward of the cusp region, and high, but variable spectral width values observed within the cusp region. To identify the spectral width boundary (SWB) between these two regions, a simple algorithm employing a spectral width threshold has often been applied to the data. However, there is not, as yet, a standard algorithm, or spectral width threshold, which is universally applied. Nor has there been any rigorous assessment of the accuracy of this method of boundary determination. This study applies a series of threshold algorithms to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms. This shows that simple threshold algorithms correctly identify the boundary location in, at the most, 50% of the cases and that the average boundary error is at least ~ 1 2 range gates (~ 1° latitude). It transpires that spatial and temporal smoothing of the spectral width data (e.g. by median filtering), before application of a threshold algorithm can increase the boundary determination accuracy to over 95% and the average boundary error to much less than a range gate. However, this is sometimes at the cost of temporal resolution in the motion of the boundary location. The algorithms are also applied to a year’s worth of spectral width data from the cusp ionosphere, measured by the Halley SuperDARN radar in Antarctica. This analysis highlights the increased accuracy of the enhanced

  6. Experimental determination of storage ring optics using orbit response measurements

    NASA Astrophysics Data System (ADS)

    Safranek, J.

    1997-02-01

    The measured response matrix giving the change in orbit at beam position monitors (BPMs) with changes in steering magnet excitation can be used to accurately calibrate the linear optics in an electron storage ring [1-8]. A computer code called LOCO (Linear Optics from Closed Orbits) was developed to analyze the NSLS X-Ray Ring measured response matrix to determine: the gradients in all 56 quadrupole magnets; the calibration of the steering magnets and BPMs; the roll of the quadrupoles, steering magnets, and BPMs about the electron beam direction; the longitudinal magnetic centers of the orbit steering magnets; the horizontal dispersion at the orbit steering magnets; and the transverse mis-alignment of the electron orbit in each of the sextupoles. Random orbit measurement error from the BPMs propagated to give only 0.04% rms error in the determination of individual quadrupole gradients and 0.4 mrad rms error in the determination of individual quadrupole rolls. Small variations of a few parts in a thousand in the quadrupole gradients within an individual family were resolved. The optics derived by LOCO gave accurate predictions of the horizontal dispersion, the beta functions, and the horizontal and vertical emittances, and it gave good qualitative agreement with the measured vertical dispersion. The improved understanding of the X-Ray Ring has enabled us to increase the synchrotron radiation brightness. The LOCO code can also be used to find the quadrupole family gradients that best correct for gradient errors in quadrupoles, in sextupoles, and from synchrotron radiation insertion devices. In this way the design periodicity of a storage ring's optics can be restored. An example of periodicity restoration will be presented for the NSLS VUV Ring. LOCO has also produced useful results when applied to the ALS storage ring [8].

  7. Atom probe trajectory mapping using experimental tip shape measurements.

    PubMed

    Haley, D; Petersen, T; Ringer, S P; Smith, G D W

    2011-11-01

    Atom probe tomography is an accurate analytical and imaging technique which can reconstruct the complex structure and composition of a specimen in three dimensions. Despite providing locally high spatial resolution, atom probe tomography suffers from global distortions due to a complex projection function between the specimen and detector which is different for each experiment and can change during a single run. To aid characterization of this projection function, this work demonstrates a method for the reverse projection of ions from an arbitrary projection surface in 3D space back to an atom probe tomography specimen surface. Experimental data from transmission electron microscopy tilt tomography are combined with point cloud surface reconstruction algorithms and finite element modelling to generate a mapping back to the original tip surface in a physically and experimentally motivated manner. As a case study, aluminium tips are imaged using transmission electron microscopy before and after atom probe tomography, and the specimen profiles used as input in surface reconstruction methods. This reconstruction method is a general procedure that can be used to generate mappings between a selected surface and a known tip shape using numerical solutions to the electrostatic equation, with quantitative solutions to the projection problem readily achievable in tens of minutes on a contemporary workstation.

  8. Experimental and theoretical comparison of NIR spectroscopy measurements of cerebral hemoglobin changes.

    PubMed

    Firbank, M; Elwell, C E; Cooper, C E; Delpy, D T

    1998-11-01

    Two near-infrared spectroscopy (NIRS) methods are available for measuring changes (Delta) in total cerebral hemoglobin concentration (CHC): 1) a continuous measurement of the changes in total hemoglobin concentration (Delta[Hb]tot) and 2) the difference between two absolute measurements of CHC, each derived from a small, controlled change in inspired O2 fraction. This paper investigates the internal consistency of these two methods by using an experimental and theoretical comparison. NIRS was used to measure [Hb]tot in five newborn piglets before and after a change in arterial PCO2. Delta[Hb]tot demonstrated a low coefficient of variation of 2.8 +/- 2.8 (SD) % which allowed changes in CO2-cerebral blood volume reactivity to be clearly discriminated. However, a high coefficient of variation of 22.8 +/- 3.5% on the DeltaCHC measurements obscured any CO2 reactivity changes. A theoretical analysis demonstrates the effects of optical pathlength, background absorption, scatter, and blood vessel diameter on both methods. For more accurate monitoring of CHC, individual measurements of optical pathlength and more accurate pulse oximetry are required.

  9. Accurate lumen diameter measurement in curved vessels in carotid ultrasound: an iterative scale-space and spatial transformation approach.

    PubMed

    Krishna Kumar, P; Araki, Tadashi; Rajan, Jeny; Saba, Luca; Lavra, Francesco; Ikeda, Nobutaka; Sharma, Aditya M; Shafique, Shoaib; Nicolaides, Andrew; Laird, John R; Gupta, Ajay; Suri, Jasjit S

    2016-12-10

    Monitoring of cerebrovascular diseases via carotid ultrasound has started to become a routine. The measurement of image-based lumen diameter (LD) or inter-adventitial diameter (IAD) is a promising approach for quantification of the degree of stenosis. The manual measurements of LD/IAD are not reliable, subjective and slow. The curvature associated with the vessels along with non-uniformity in the plaque growth poses further challenges. This study uses a novel and generalized approach for automated LD and IAD measurement based on a combination of spatial transformation and scale-space. In this iterative procedure, the scale-space is first used to get the lumen axis which is then used with spatial image transformation paradigm to get a transformed image. The scale-space is then reapplied to retrieve the lumen region and boundary in the transformed framework. Then, inverse transformation is applied to display the results in original image framework. Two hundred and two patients' left and right common carotid artery (404 carotid images) B-mode ultrasound images were retrospectively analyzed. The validation of our algorithm has done against the two manual expert tracings. The coefficient of correlation between the two manual tracings for LD was 0.98 (p < 0.0001) and 0.99 (p < 0.0001), respectively. The precision of merit between the manual expert tracings and the automated system was 97.7 and 98.7%, respectively. The experimental analysis demonstrated superior performance of the proposed method over conventional approaches. Several statistical tests demonstrated the stability and reliability of the automated system.

  10. Contact Angle Measurements Using a Simplified Experimental Setup

    ERIC Educational Resources Information Center

    Lamour, Guillaume; Hamraoui, Ahmed; Buvailo, Andrii; Xing, Yangjun; Keuleyan, Sean; Prakash, Vivek; Eftekhari-Bafrooei, Ali; Borguet, Eric

    2010-01-01

    A basic and affordable experimental apparatus is described that measures the static contact angle of a liquid drop in contact with a solid. The image of the drop is made with a simple digital camera by taking a picture that is magnified by an optical lens. The profile of the drop is then processed with ImageJ free software. The ImageJ contact…

  11. Control of experimental uncertainties in filtered Rayleigh scattering measurements

    NASA Technical Reports Server (NTRS)

    Forkey, Joseph N.; Finkelstein, N. D.; Lempert, Walter R.; Miles, Richard B.

    1995-01-01

    Filtered Rayleigh Scattering is a technique which allows for measurement of velocity, temperature, and pressure in unseeded flows, spatially resolved in 2-dimensions. We present an overview of the major components of a Filtered Rayleigh Scattering system. In particular, we develop and discuss a detailed theoretical model along with associated model parameters and related uncertainties. Based on this model, we then present experimental results for ambient room air and for a Mach 2 free jet, including spatially resolved measurements of velocity, temperature, and pressure.

  12. Experimental studies on near-field holographic antenna measurement

    NASA Astrophysics Data System (ADS)

    Zuo, Yingxi; Xu, Linfen; An, Hongye; Sun, Jixian; Lou, Zheng; Yang, Ji; Zhang, Xuguo; Li, Zhenqiang; Lu, Dengrong; Pang, Xinghai; Li, Yang

    2016-07-01

    A near-field millimeter-wave holography system operating in the 3-mm waveband have been developed as a prototype for DATE5, a 5-m terahertz telescope proposed to be deployed at Dome A, Antarctica. Experimental measurements at 92 GHz have been made on a 1.45-m test antenna. During the night time at which the ambient temperature doesn't vary rapidly, a 75-minute repeatability (repeating measurement 3 times) of 2.3 μm rms has been achieved with an aperture resolution of 46 mm. A local surface change of known value is correctly detected. After long-time repeating measurements, thermal-induced feed displacement is also detected with an accuracy of approximately 20 μm. Random error factors of the experiment system are evaluated and their contributions to the derived surface error are also simulated, showing that relative poor pointing of the test antenna is the major factor limiting the measurement repeatability.

  13. Synchrotron radiation measurement of multiphase fluid saturations in porous media: Experimental technique and error analysis

    NASA Astrophysics Data System (ADS)

    Tuck, David M.; Bierck, Barnes R.; Jaffé, Peter R.

    1998-06-01

    Multiphase flow in porous media is an important research topic. In situ, nondestructive experimental methods for studying multiphase flow are important for improving our understanding and the theory. Rapid changes in fluid saturation, characteristic of immiscible displacement, are difficult to measure accurately using gamma rays due to practical restrictions on source strength. Our objective is to describe a synchrotron radiation technique for rapid, nondestructive saturation measurements of multiple fluids in porous media, and to present a precision and accuracy analysis of the technique. Synchrotron radiation provides a high intensity, inherently collimated photon beam of tunable energy which can yield accurate measurements of fluid saturation in just one second. Measurements were obtained with precision of ±0.01 or better for tetrachloroethylene (PCE) in a 2.5 cm thick glass-bead porous medium using a counting time of 1 s. The normal distribution was shown to provide acceptable confidence limits for PCE saturation changes. Sources of error include heat load on the monochromator, periodic movement of the source beam, and errors in stepping-motor positioning system. Hypodermic needles pushed into the medium to inject PCE changed porosity in a region approximately ±1 mm of the injection point. Improved mass balance between the known and measured PCE injection volumes was obtained when appropriate corrections were applied to calibration values near the injection point.

  14. Implications of (Less) Accurate Mass-Radius-Measurements for the Habitability of Extrasolar Terrestrial Planets: Why Do We Need PLATO?

    NASA Astrophysics Data System (ADS)

    Noack, L.; Wagner, F. W.; Plesa, A.-C.; Höning, D.; Sohl, F.; Breuer, D.; Rauer, H.

    2012-04-01

    Several space missions (CoRoT, Kepler and others) already provided promising candidates for terrestrial exoplanets (i.e. with masses less than about 10 Earth masses) and thereby triggered an exciting new research branch of planetary modelling to investigate the possible habitability of such planets. Earth analogues (low-mass planets with an Earth-like structure and composition) are likely to be found in the near future with new missions such as the proposed M3 mission PLATO. Planets may be more diverse in the universe than they are in the solar system. Our neighbouring planets in the habitable zone are all terrestrial by the means of being differentiated into an iron core, a silicate mantle and a crust. To reliably determine the interior structure of an exoplanet, measurements of mass and radius have to be sufficiently accurate (around +/-2% error allowed for the radius and +/-5% for the mass). An Earth-size planet with an Earth-like mass but an expected error of ~15% in mass for example may have either a Mercury-like, an Earth-like or a Moon-like (i.e. small iron core) structure [1,2]. Even though the atmospheric escape is not strongly influenced by the interior structure, the outgassing of volatiles and the likeliness of plate tectonics and an ongoing carbon-cycle may be very different. Our investigations show, that a planet with a small silicate mantle is less likely to shift into the plate-tectonics regime, cools faster (which may lead to the loss of a magnetic field after a short time) and outgasses less volatiles than a planet with the same mass but a large silicate mantle and small iron core. To be able to address the habitability of exoplanets, space missions such as PLATO, which can lead up to 2% accuracy in radius [3], are extremely important. Moreover, information about the occurrence of different planetary types helps us to better understand the formation of planetary systems and to further constrain the Drake's equation, which gives an estimate of the

  15. Experimental Air Embolism: Measurement of Microbubbles Using the Coulter Counter®

    PubMed Central

    Grulke, D. C.; Marsh, N. A.; Hills, B. A.

    1973-01-01

    Microbubbles in the range 20-250 μm were produced with fine hypodermic needles (0·001, 0·002 and 0·003 inch internal diameter) and were measured using a conventional Coulter Counter. Various bubble sizes could be obtained by varying combinations of needle size, gas pressure, liquid surfactant content and liquid flow rate. Bubbles produced and measured in this way were found to have a very narrow size distribution (80% of the bubbles falling within ± 2 μm of the mean radius) and could be generated at relatively constant frequencies. Over the entire bubble size range, the Coulter Counter method correlated well with two other bubble measuring methods: terminal rise velocity and volume flow rate of gas divided by bubble frequency. It is suggested that this method will enable the introduction of a known number of accurately sized microbubbles into the circulation for the purpose of studying experimental gas embolism. ImagesFig. 2 PMID:4783166

  16. Uncertainty principle for experimental measurements: Fast versus slow probes

    PubMed Central

    Hansmann, P.; Ayral, T.; Tejeda, A.; Biermann, S.

    2016-01-01

    The result of a physical measurement depends on the time scale of the experimental probe. In solid-state systems, this simple quantum mechanical principle has far-reaching consequences: the interplay of several degrees of freedom close to charge, spin or orbital instabilities combined with the disparity of the time scales associated to their fluctuations can lead to seemingly contradictory experimental findings. A particularly striking example is provided by systems of adatoms adsorbed on semiconductor surfaces where different experiments – angle-resolved photoemission, scanning tunneling microscopy and core-level spectroscopy – suggest different ordering phenomena. Using most recent first principles many-body techniques, we resolve this puzzle by invoking the time scales of fluctuations when approaching the different instabilities. These findings suggest a re-interpretation of ordering phenomena and their fluctuations in a wide class of solid-state systems ranging from organic materials to high-temperature superconducting cuprates. PMID:26829902

  17. Regression with repeated measures in the experimental units.

    PubMed

    Garsd, A

    1999-01-01

    The most satisfactory solution to the problem of modeling a family of regressions with repeated measures in the experimental units is multivariate in nature. However, multivariate methods are difficult to follow and implement. Furthermore, by keeping the focus on the experimental unit, a family of simple univariate linear models will often parallel both the investigator's intuitive grasp of the statistical task at hand. We present two examples based on data from a study of the suckling stimulus during breastfeeding in newborn infants. We show how a family of regression lines can provide useful, if approximate, answers to the questions of interest. One example involves a regression setting proper and the other a typical case of correlation. We discuss alternative univariate models that may be useful for this type of problems.

  18. Uncertainty principle for experimental measurements: Fast versus slow probes.

    PubMed

    Hansmann, P; Ayral, T; Tejeda, A; Biermann, S

    2016-02-01

    The result of a physical measurement depends on the time scale of the experimental probe. In solid-state systems, this simple quantum mechanical principle has far-reaching consequences: the interplay of several degrees of freedom close to charge, spin or orbital instabilities combined with the disparity of the time scales associated to their fluctuations can lead to seemingly contradictory experimental findings. A particularly striking example is provided by systems of adatoms adsorbed on semiconductor surfaces where different experiments--angle-resolved photoemission, scanning tunneling microscopy and core-level spectroscopy--suggest different ordering phenomena. Using most recent first principles many-body techniques, we resolve this puzzle by invoking the time scales of fluctuations when approaching the different instabilities. These findings suggest a re-interpretation of ordering phenomena and their fluctuations in a wide class of solid-state systems ranging from organic materials to high-temperature superconducting cuprates.

  19. Experimental measurements and noise analysis of a cryogenic radiometer

    SciTech Connect

    Carr, S. M.; Woods, S. I.; Jung, T. M.; Carter, A. C.; Datla, R. U.

    2014-07-15

    A cryogenic radiometer device, intended for use as part of an electrical-substitution radiometer, was measured at low temperature. The device consists of a receiver cavity mechanically and thermally connected to a temperature-controlled stage through a thin-walled polyimide tube which serves as a weak thermal link. With the temperature difference between the receiver and the stage measured in millikelvin and the electrical power measured in picowatts, the measured responsivity was 4700 K/mW and the measured thermal time constant was 14 s at a stage temperature of 1.885 K. Noise analysis in terms of Noise Equivalent Power (NEP) was used to quantify the various fundamental and technical noise contributions, including phonon noise and Johnson-Nyquist noise. The noise analysis clarifies the path toward a cryogenic radiometer with a noise floor limited by fundamental phonon noise, where the magnitude of the phonon NEP is 6.5 fW/√(Hz) for the measured experimental parameters.

  20. The experimental technique of the G^0 measurement.

    NASA Astrophysics Data System (ADS)

    Roche, Julie

    2001-10-01

    The G^0 experiment(JLab experiment E00-006, D.H. Beck, spokesperson.) will measure the parity-violating asymmetries in elastic electron-nucleon scattering. The experiment will be performed in Hall C at Jefferson Lab using a dedicated apparatus. In order to achieve the required statistical accuracy of the measurements, a super-conducting toroidal spectrometer, with azimuthally symmetric angular acceptance, and an associated cryogenic target have been constructed. The Focal Plane Detectors are arranged in 8 arrays of 16 arc-shaped scintillator pairs providing a fast signal compatible with the high rates of this counting experiment. For the forward angle measurement, custom built electronics will provide a time-of-flight measurement discriminating elastic recoil protons from pions and inelastic protons. For the backward angle measurements, additional scintillators and Cerenkov counters will provide separation of the elastic electrons from inelastic electrons and pions. An overview of the experimental apparatus and method for the G^0 measurement will be presented.

  1. Reflectance spectroscopy of gold nanoshells: computational predictions and experimental measurements

    NASA Astrophysics Data System (ADS)

    Lin, Alex W. H.; Lewinski, Nastassja A.; Lee, Min-Ho; Drezek, Rebekah A.

    2006-10-01

    Gold nanoshells are concentric spherical constructs that possess highly desirable optical responses in the near infrared. Gold nanoshells consist of a thin outer gold shell and a silica core and can be used for both diagnostic and therapeutic purposes by tuning the optical response through changing the core-shell ratio as well as the overall size. Although optical properties of gold nanoshells have already been well documented, the reflectance characteristics are not well understood and have not yet been elucidated by experimental measurements. Yet, in order to use gold nanoshells as an optical contrast agent for scattering-based optical methods such as reflectance spectroscopy, it is critical to characterize the reflectance behavior. With this in mind, we used a fiber-optic-based spectrometer to measure diffuse reflectance of gold nanoshell suspensions from 500 nm to 900 nm. Experimental results show that gold nanoshells cause a significant increase in the measured reflectance. Spectral features associated with scattering from large angles ( 180°) were observed at low nanoshell concentrations. Monte Carlo modeling of gold nanoshells reflectance demonstrated the efficacy of using such methods to predict diffuse reflectance. Our studies suggest that gold nanoshells are an excellent candidate as optical contrast agents and that Monte Carlo methods are a useful tool for optimizing nanoshells best suited for scattering-based optical methods.

  2. Measuring and Test Workbenches of Experimental Complex NEVOD

    NASA Astrophysics Data System (ADS)

    Kompaniets, K. G.; Amelchakov, M. B.; Ampilogov, N. V.; Chernov, D. V.; Khokhlov, S. S.; Kindin, V. V.; Likiy, O. I.; Shulzhenko, I. A.; Shutenko, V. V.; Yashin, I. I.; Zadeba, E. A.

    The measuring and test automated workbenches used to maintain the health of existing and commissioning of new detectors of the unique scientific facility "Experimental complex NEVOD" are described. The structure of workbenches and their main characteristics are presented. Workbenches include standard high-precision instruments manufactured by Tektronix, CAEN, Aktakom, and specially designed components and modules. Procedures of measurements and tests are carried out in automatic mode under control of computer. Management programs of workbenches are written on the basis of original methods, allowing to obtain reliable and complete information on the status and characteristics of the components of physical systems. Calibration of equipment is carried out through registration of various components of cosmic rays.

  3. Mode Content Determination of Terahertz Corrugated Waveguides Using Experimentally Measured Radiated Field Patterns

    PubMed Central

    Jawla, Sudheer K.; Nanni, Emilio A.; Shapiro, Michael A.; Woskov, Paul P.; Temkin, Richard J.

    2012-01-01

    This work focuses on the accuracy of the mode content measurements in an overmoded corrugated waveguide using measured radiated field patterns. Experimental results were obtained at 250 GHz using a vector network analyzer with over 70 dB of dynamic range. The intensity and phase profiles of the fields radiated from the end of the 19 mm diameter helically tapped brass waveguide were measured on planes at 7, 10, and 13 cm from the waveguide end. The measured fields were back propagated to the waveguide aperture to provide three independent estimates of the field at the waveguide exit aperture. Projecting that field onto the modes of the guide determined the waveguide mode content. The three independent mode content estimates were found to agree with one another to an accuracy of better than ±0.3%. These direct determinations of the mode content were compared with indirect measurements using the experimentally measured amplitude in three planes, with the phase determined by a phase retrieval algorithm. The phase retrieval technique using the planes at 7, 10, and 13 cm yielded a mode content estimate in excellent agreement, within 0.3%, of the direct measurements. Phase retrieval results using planes at 10, 20, and 30 cm were less accurate due to truncation of the measurement in the transverse plane. The reported measurements benefited greatly from a precise mechanical alignment of the scanner with respect to the waveguide axis. These results will help to understand the accuracy of mode content measurements made directly in cold test and indirectly in hot test using the phase retrieval technique. PMID:25264391

  4. Experimental difficulties in measuring the scattering of sound by sound

    SciTech Connect

    TenCate, J.A. )

    1994-11-01

    The question of whether one sound beam can interact with another at nonzero angle and scatter nonlinearly generated sound outside the mutual interaction region has been debated since the 1950s. Experimental work on this problem has left the question unresolved. This presentation describes experimental difficulties associated with measuring scattered sound produced by real diffracting primary beams. Optimal conditions for observing scattered sound, as outlined by Berntsen [ital et] [ital al]. [J. Acoust. Soc. Am. [bold 86], 1968 (1989)] and by Darvennes and Hamilton [J. Acoust. Soc. Am. [bold 87], 1955 (1990)], are reviewed in relation to the design of our own experiments. Our experiments were performed with either two uniform circular sources in water (megahertz frequencies), or with one circular source and the other a shaded source with lower sidelobes. A variety of primary frequency ratios, interaction angles, and other parameters were considered. Comparison of the primary beam patterns with measured sum and difference frequency field patterns reveals the difficulty in identifying which components of the latter correspond to scattered'' sound. It is concluded that two Gaussian-type sources with exceedingly good sidelobe suppression are needed to perform a reasonable experiment. [Work supported by the Packard Foundation and ONR.] [sup a]Present address: Earth and Environmental Sciences Division, Mail Stop D443, Los Alamos National Laboratory, Los Alamos, NM 87545.

  5. Deriving Structural Information from Experimentally Measured Data on Biomolecules.

    PubMed

    van Gunsteren, Wilfred F; Allison, Jane R; Daura, Xavier; Dolenc, Jožica; Hansen, Niels; Mark, Alan E; Oostenbrink, Chris; Rusu, Victor H; Smith, Lorna J

    2016-12-23

    During the past half century, the number and accuracy of experimental techniques that can deliver values of observables for biomolecular systems have been steadily increasing. The conversion of a measured value Q(exp) of an observable quantity Q into structural information is, however, a task beset with theoretical and practical problems: 1) insufficient or inaccurate values of Q(exp) , 2) inaccuracies in the function Q(r→) used to relate the quantity Q to structure r→ , 3) how to account for the averaging inherent in the measurement of Q(exp) , 4) how to handle the possible multiple-valuedness of the inverse r→(Q) of the function Q(r→) , to mention a few. These apply to a variety of observable quantities Q and measurement techniques such as X-ray and neutron diffraction, small-angle and wide-angle X-ray scattering, free-electron laser imaging, cryo-electron microscopy, nuclear magnetic resonance, electron paramagnetic resonance, infrared and Raman spectroscopy, circular dichroism, Förster resonance energy transfer, atomic force microscopy and ion-mobility mass spectrometry. The process of deriving structural information from measured data is reviewed with an eye to non-experts and newcomers in the field using examples from the literature of the effect of the various choices and approximations involved in the process. A list of choices to be avoided is provided.

  6. Experimental optical phase measurement at the exact Heisenberg limit (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Daryanoosh, Shakib; Slussarenko, Sergei; Wiseman, Howard M.; Pryde, Geoff J.

    2016-10-01

    Optical phase measurement through its application in quantum metrology has pushed the precision limit with which some physical quantities can be measured accurately. At the very fundamental level, the laws of quantum mechanics dictate that the uncertainty in phase estimations scales as 1/N, where N is the number of quantum resources employed in the protocol [1]. This is the well known Heisenberg limit (HL) which is quadratically better than the traditional precision limit known as the standard quantum limit (SQL) with uncertainty asymptotically scaling as 1/&sqrt{N} [1]. Several experiments have demonstrated that the SQL can be beaten by using an entangled state as the probe and a specific measurement scheme for ab initio estimation of unknown phases [2,3]. It has also been shown experimentally that even in the absence of the entanglement one can measure an unknown phase with imprecision scaling at the HL [4]. In this work we first present a new protocol able to estimate an optical phase at the Heisenberg limit, and then experimentally explore fundamental and practical issues in generating high-quality novel entangled states, for use in this protocol and beyond. Our aim in this study is to measure an unknown phase in the interval [0,2π) with uncertainty attaining the exact HL. There is a condition that should be met to address this objective: preparation of an optimal state [5]. This would cover part of the presentation through which we explain how to experimentally realise such an optimal state with the current technological limitations and the feasibility of the scheme. In particular, we generate an entangled 3-photon (2-photon) state of specific superposition of GHZ (Bell) states. Our numerical simulation of the phase measurement gate together with the experimental outcomes show that the created state should have a high fidelity and purity to be able to have the phase uncertainty achieving the exact HL. Therefore, we briefly explain the modelling for

  7. A non-contact method based on multiple signal classification algorithm to reduce the measurement time for accurately heart rate detection.

    PubMed

    Bechet, P; Mitran, R; Munteanu, M

    2013-08-01

    Non-contact methods for the assessment of vital signs are of great interest for specialists due to the benefits obtained in both medical and special applications, such as those for surveillance, monitoring, and search and rescue. This paper investigates the possibility of implementing a digital processing algorithm based on the MUSIC (Multiple Signal Classification) parametric spectral estimation in order to reduce the observation time needed to accurately measure the heart rate. It demonstrates that, by proper dimensioning the signal subspace, the MUSIC algorithm can be optimized in order to accurately assess the heart rate during an 8-28 s time interval. The validation of the processing algorithm performance was achieved by minimizing the mean error of the heart rate after performing simultaneous comparative measurements on several subjects. In order to calculate the error the reference value of heart rate was measured using a classic measurement system through direct contact.

  8. A non-contact method based on multiple signal classification algorithm to reduce the measurement time for accurately heart rate detection

    NASA Astrophysics Data System (ADS)

    Bechet, P.; Mitran, R.; Munteanu, M.

    2013-08-01

    Non-contact methods for the assessment of vital signs are of great interest for specialists due to the benefits obtained in both medical and special applications, such as those for surveillance, monitoring, and search and rescue. This paper investigates the possibility of implementing a digital processing algorithm based on the MUSIC (Multiple Signal Classification) parametric spectral estimation in order to reduce the observation time needed to accurately measure the heart rate. It demonstrates that, by proper dimensioning the signal subspace, the MUSIC algorithm can be optimized in order to accurately assess the heart rate during an 8-28 s time interval. The validation of the processing algorithm performance was achieved by minimizing the mean error of the heart rate after performing simultaneous comparative measurements on several subjects. In order to calculate the error the reference value of heart rate was measured using a classic measurement system through direct contact.

  9. Experimental Measurement and Numerical Modeling of the Effective Thermal Conductivity of TRISO Fuel Compacts

    SciTech Connect

    Folsom, Charles; Xing, Changhu; Jensen, Colby; Ban, Heng; Marshall, Douglas W.

    2015-03-01

    Accurate modeling capability of thermal conductivity of tristructural-isotropic (TRISO) fuel compacts is important to fuel performance modeling and safety of Generation IV reactors. To date, the effective thermal conductivity (ETC) of tristructural-isotropic (TRISO) fuel compacts has not been measured directly. The composite fuel is a complicated structure comprised of layered particles in a graphite matrix. In this work, finite element modeling is used to validate an analytic ETC model for application to the composite fuel material for particle-volume fractions up to 40%. The effect of each individual layer of a TRISO particle is analyzed showing that the overall ETC of the compact is most sensitive to the outer layer constituent. In conjunction with the modeling results, the thermal conductivity of matrix-graphite compacts and the ETC of surrogate TRISO fuel compacts have been successfully measured using a previously developed measurement system. The ETC of the surrogate fuel compacts varies between 50 and 30 W m-1 K-1 over a temperature range of 50-600°C. As a result of the numerical modeling and experimental measurements of the fuel compacts, a new model and approach for analyzing the effect of compact constituent materials on ETC is proposed that can estimate the fuel compact ETC with approximately 15-20% more accuracy than the old method. Using the ETC model with measured thermal conductivity of the graphite matrix-only material indicate that, in the composite form, the matrix material has a much greater thermal conductivity, which is attributed to the high anisotropy of graphite thermal conductivity. Therefore, simpler measurements of individual TRISO compact constituents combined with an analytic ETC model, will not provide accurate predictions of overall ETC of the compacts emphasizing the need for measurements of composite, surrogate compacts.

  10. Performing Accurate Rigid Kinematics Measurements from 3D in vivo Image Sequences through Median Consensus Simultaneous Registration.

    PubMed

    Cresson, T; Jacq, J; Burdin, V; Roux, Ch

    2005-01-01

    While focusing at accurate 3D joint kinematics, this paper explores the problem of how to perform a robust rigid registration for a sequence of object surfaces observed using standard 3D medical imaging techniques. Each object instance is assumed to give access to a polyhedral encoding of its boundary. We consider the case where object instances are noised with significant truncations and segmentation errors. The proposed method aims to tackle this problem in a global way, fully exploiting the duality between redundancy and complementarity of the available instances set. The algorithm operates through robust and simultaneous registration of all geometrical instances on a virtual instance accounting for their median consensus. When compared with standard robust techniques, trials reveal significant gains, as much in robustness as in accuracy. The considered applications are mainly focused on generating highly accurate kinematics in relation to the bone structures of the most complex joints - the tarsus and the carpus - for which no alternative examination techniques exist, enabling fine morphological analysis as well as access to internal joint motions.

  11. Application of measurement configuration optimization for accurate metrology of sub-wavelength dimensions in multilayer gratings using optical scatterometry.

    PubMed

    Zhu, Jinlong; Shi, Yating; Goddard, Lynford L; Liu, Shiyuan

    2016-09-01

    Critical dimension measurement accuracy in optical scatterometry relies not only on the systematic noise level of instruments and the reliability of forward modeling algorithms, but also heavily on the measurement configuration. To construct a set of potentially high-accuracy configurations, we apply a general measurement configuration optimization method based on error propagation theory and singular value decomposition, by which the measurement accuracy is approximated as a function of a pseudo Jacobian with respect to the measurement configurations. Simulations and experiments for the optical metrology of a sub-wavelength deep-etched multilayer grating establish the feasibility of the proposed method.

  12. An experimental assembly for precise measurement of thermal accommodation coefficients

    NASA Astrophysics Data System (ADS)

    Trott, Wayne M.; Castañeda, Jaime N.; Torczynski, John R.; Gallis, Michael A.; Rader, Daniel J.

    2011-03-01

    An experimental apparatus has been developed to determine thermal accommodation coefficients for a variety of gas-surface combinations. Results are obtained primarily through measurement of the pressure dependence of the conductive heat flux between parallel plates separated by a gas-filled gap. Measured heat-flux data are used in a formula based on Direct Simulation Monte Carlo (DSMC) simulations to determine the coefficients. The assembly also features a complementary capability for measuring the variation in gas density between the plates using electron-beam fluorescence. Surface materials examined include 304 stainless steel, gold, aluminum, platinum, silicon, silicon nitride, and polysilicon. Effects of gas composition, surface roughness, and surface contamination have been investigated with this system; the behavior of gas mixtures has also been explored. Without special cleaning procedures, thermal accommodation coefficients for most materials and surface finishes were determined to be near 0.95, 0.85, and 0.45 for argon, nitrogen, and helium, respectively. Surface cleaning by in situ argon-plasma treatment reduced coefficient values by up to 0.10 for helium and by ˜0.05 for nitrogen and argon. Results for both single-species and gas-mixture experiments compare favorably to DSMC simulations.

  13. Experimental evaluation of tachistoscopic measurement: a step beyond Wundt's criticism.

    PubMed

    Voboril, Dalibor; Jelínek, Martin; Kvĕton, Petr

    2014-01-01

    This study was designed to assess the possible systematic bias in measurements obtained using tachistoscopic devices from different historical periods of psychological research. Four different tachistoscopic devices were used for brief presentations of stimuli in a letter recognition task. The research sample consisted of 24 participants (12 female, 12 male) in a within-subject experimental design with complete counterbalancing of 4 conditions defined by 4 instrument types: fall tachistoscope, tachistoscope with camera-like shutter, and computer-based tachistoscopes with cathode ray tube and liquid crystal diode display screens. The effects of experimental conditions were examined using a linear mixed model analysis. Our experiment demonstrated that even in standardized settings the type of tachistoscope used for stimulus presentation systematically influenced the participants' performance. We found that the lowest number of correctly recalled stimuli, as well as the highest number of erroneously recalled stimuli, was produced in the camera-like tachistoscope condition. Together, these findings suggest that when results from studies involving tachistoscopic experiments are reviewed, the unique characteristics of each particular instrument used must be considered carefully.

  14. Effect of Electron Seeding on Experimentally Measured Multipactor Discharge Threshold

    NASA Astrophysics Data System (ADS)

    Noland, Jonathan; Graves, Timothy; Lemon, Colby; Looper, Mark; Farkas, Alex

    2012-10-01

    Multipactor is a vacuum phenomenon in which electrons, moving in resonance with an externally applied electric field, impact material surfaces. If the number of secondary electrons created per primary electron impact averages more than unity, the resonant interaction can lead to an electron avalanche. Multipactor is a generally undesirable phenomenon, as it can cause local heating, absorb power, or cause detuning of RF circuits. In order to increase the probability of multipactor initiation, test facilities often employ various seeding sources such as radioactive sources (Cesium 137, Strontium 90), electron guns, or photon sources. Even with these sources, the voltage for multipactor initiation is not certain as parameters such as material type, RF pulse length, and device wall thickness can all affect seed electron flux and energy in critical gap regions, and hence the measured voltage threshold. This study investigates the effects of seed electron source type (e.g., photons versus beta particles), material type, gap size, and RF pulse length variation on multipactor threshold. In addition to the experimental work, GEANT4 simulations will be used to estimate the production rate of low energy electrons (< 5 keV) by high energy electrons and photons. A comparison of the experimental fluxes to the typical energetic photon and particle fluxes experienced by spacecraft in various orbits will also be made. Initial results indicate that for a simple, parallel plate device made of aluminum, there is no threshold variation (with seed electrons versus with no seed electrons) under continuous-wave RF exposure.

  15. Experimental measurements of motion cue effects on STOL approach tasks

    NASA Technical Reports Server (NTRS)

    Ringland, R. F.; Stapleford, R. L.

    1972-01-01

    An experimental program to investigate the effects of motion cues on STOL approach is presented. The simulator used was the Six-Degrees-of-Freedom Motion Simulator (S.01) at Ames Research Center of NASA which has ?2.7 m travel longitudinally and laterally and ?2.5 m travel vertically. Three major experiments, characterized as tracking tasks, were conducted under fixed and moving base conditions: (1) A simulated IFR approach of the Augmentor Wing Jet STOL Research Aircraft (AWJSRA), (2) a simulated VFR task with the same aircraft, and (3) a single-axis task having only linear acceleration as the motion cue. Tracking performance was measured in terms of the variances of several motion variables, pilot vehicle describing functions, and pilot commentary.

  16. Experimental measurement on movement of spiral-type capsule endoscope

    PubMed Central

    Yang, Wanan; Dai, Houde; He, Yong; Qin, Fengqing

    2016-01-01

    Wireless capsule endoscope achieved great success, however, the maneuvering of wireless capsule endoscope is challenging at present. A magnetic driving instrument, including two bar magnets, a stepper motor, a motor driver, a motor controller, and a power supplier, was developed to generate rotational magnetic fields. Permanent magnet ring, magnetized as S and N poles radially and mounted spiral structure on the surface, acted as a capsule. The maximum torque passing to the capsule, rotational synchronization of capsule and motor, and the translational speed of capsule, were measured in ex vivo porcine large intestine. The experimental results illustrate that the rotational movement of the spiral-type capsule in the intestine is feasible and the cost of the magnetic driving equipment is low. As a result, the solution is promising in the future controllability. PMID:26848279

  17. Experimental Measurements of Spreading of Volatile Liquid Droplets

    NASA Technical Reports Server (NTRS)

    Zhang, Neng-Li; Chao, David F.

    2001-01-01

    Based on the laser shadowgraphic system used by the first author of the present paper, a simple optical system, which combined the laser shadowgraphy and the direct magnified-photography, has been developed to measure the contact angle, the spreading speed, and the evaporation rate. Additionally, the system can also visualize thermocapillary convection inside of a sessile drop simultaneously. The experimental results show that evaporation/condensation and thermocapillary convection in the sessile drop induced by the evaporation strongly affects the wetting and spreading of the drop. Condensation always promotes the wetting and spreading of the drop. Evaporation may increase or decrease the contact angle of the evaporating sessile drops, depending on the evaporation rate. The thermocapillary convection in the drop induced by the evaporation enhances the effects of evaporation to suppress the spreading.

  18. Experimental measurement on movement of spiral-type capsule endoscope.

    PubMed

    Yang, Wanan; Dai, Houde; He, Yong; Qin, Fengqing

    2016-01-01

    Wireless capsule endoscope achieved great success, however, the maneuvering of wireless capsule endoscope is challenging at present. A magnetic driving instrument, including two bar magnets, a stepper motor, a motor driver, a motor controller, and a power supplier, was developed to generate rotational magnetic fields. Permanent magnet ring, magnetized as S and N poles radially and mounted spiral structure on the surface, acted as a capsule. The maximum torque passing to the capsule, rotational synchronization of capsule and motor, and the translational speed of capsule, were measured in ex vivo porcine large intestine. The experimental results illustrate that the rotational movement of the spiral-type capsule in the intestine is feasible and the cost of the magnetic driving equipment is low. As a result, the solution is promising in the future controllability.

  19. White-light interferometer with dispersion: an accurate fiber-optic sensor for the measurement of distance.

    PubMed

    Pavlícek, Pavel; Häusler, Gerd

    2005-05-20

    We present a fiber-optical sensor for distance measurement of smooth and rough surfaces that is based on white-light interferometry; the sensor measures the distance from the sample surface to the sensor head. Because white light is used, the measurement is absolute. The measurement uncertainty depends not on the aperture of the optical system but only on the properties of the rough surface and is commonly approximately 1 microm. The measurement range is approximately 1 mm. The sensor includes no mechanical moving parts; mechanical movement is replaced by the spectral decomposition of light at the interferometer output. The absence of mechanical moving parts enables a high measuring rate to be reached.

  20. Progress in accurate measurements of sub-surface flows near the solar limb using ring-diagram analysis

    NASA Astrophysics Data System (ADS)

    Baldner, Charles; Bogart, Richard S.

    2016-05-01

    The use of helioseismology to study the properties of the Sun has yielded very high precision measurements of solar flows throughout much of the interior. It has been apparent for many years, however, that the accuracy of many of these measurements is suspect due to significant systematic effects in helioseismic techniques. The most well-known effect in flow measurements is sometimes referred to as the `center-to-limb' effect, in which flow measurements depend strongly on the distance of the measurement from the center of the observed solar disk. Attempts have already been made to explain the origin of this error (e.g. Balder & Schou 2012) and to correct it (e.g. Zhao et al. 2011). Significant work remains, however.In this work, we report on continued efforts to precisely characterize the effect of position on the observed disk on flow measurements in the HMI ring diagram pipeline, and from other HMI data. Our efforts are focused on 1) quantifying the non-radial systematic effect in flow measurements; 2) understanding the effect of the underlying model used in the mode parameter estimations; and 3) characterizing the difference between helioseismic measurements made with different observed quantities.

  1. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to ...

  2. Accurate and high-performance 3D position measurement of fiducial marks by stereoscopic system for railway track inspection

    NASA Astrophysics Data System (ADS)

    Gorbachev, Alexey A.; Serikova, Mariya G.; Pantyushina, Ekaterina N.; Volkova, Daria A.

    2016-04-01

    Modern demands for railway track measurements require high accuracy (about 2-5 mm) of rails placement along the track to ensure smooth, safe and fast transportation. As a mean for railways geometry measurements we suggest a stereoscopic system which measures 3D position of fiducial marks arranged along the track by image processing algorithms. The system accuracy was verified during laboratory tests by comparison with precise laser tracker indications. The accuracy of +/-1.5 mm within a measurement volume 150×400×5000 mm was achieved during the tests. This confirmed that the stereoscopic system demonstrates good measurement accuracy and can be potentially used as fully automated mean for railway track inspection.

  3. Electron cyclotron emission measurements on the Texas Experimental Tokamak

    SciTech Connect

    Austin, M.E. Jr.

    1992-01-01

    A ten-channel grating polychromator was designed, constructed, and installed on the Texas Experimental Tokamak to monitor the second harmonic electron cyclotron emission. Electron temperature profiles were derived from measurements of the optically thick radiation for a variety of plasma confinement experiments. The radial and temporal evolution of T[sub e] has been characterized for electron cyclotron heated discharges with 150 kW of 60 GHz power. Comparisons were made of the heating efficiency of two type of ECH launchers. A focussed launcher was shown to have slightly better heating efficiency than an unfocussed launcher; however, the focussed antenna did not yield significantly higher electron temperatures as expected. A study of the time evolution of the electron temperature indicated that increased sawtooth activity limited the effectiveness of the focussed launcher. A focussing hog-horn antenna was fabricated and installed on the inboard side of the tokamak to measure emission directed towards the high-field side during ECH. Comparison of the radiation temperature profiles from low-field side and high-field side antennas indicates the creation of a nonthermal electron distribution by the heating. The results of the experiment compare favorably with theoretical predictions from a quasi-linear Fokker-Planck code of a 6 keV nonthermal population with a density about 1 percent of the thermal density.

  4. Experimental measurement and modeling of snow accumulation and snowmelt in a mountain microcatchment

    NASA Astrophysics Data System (ADS)

    Danko, Michal; Krajčí, Pavel; Hlavčo, Jozef; Kostka, Zdeněk; Holko, Ladislav

    2016-04-01

    Fieldwork is a very useful source of data in all geosciences. This naturally applies also to the snow hydrology. Snow accumulation and snowmelt are spatially very heterogeneous especially in non-forested, mountain environments. Direct field measurements provide the most accurate information about it. Quantification and understanding of processes, that cause these spatial differences are crucial in prediction and modelling of runoff volumes in spring snowmelt period. This study presents possibilities of detailed measurement and modeling of snow cover characteristics in a mountain experimental microcatchment located in northern part of Slovakia in Western Tatra mountains. Catchment area is 0.059 km2 and mean altitude is 1500 m a.s.l. Measurement network consists of 27 snow poles, 3 small snow lysimeters, discharge measurement device and standard automatic weather station. Snow depth and snow water equivalent (SWE) were measured twice a month near the snow poles. These measurements were used to estimate spatial differences in accumulation of SWE. Snowmelt outflow was measured by small snow lysimeters. Measurements were performed in winter 2014/2015. Snow water equivalent variability was very high in such a small area. Differences between particular measuring points reached 600 mm in time of maximum SWE. The results indicated good performance of a snow lysimeter in case of snowmelt timing identification. Increase of snowmelt measured by the snow lysimeter had the same timing as increase in discharge at catchment's outlet and the same timing as the increase in air temperature above the freezing point. Measured data were afterwards used in distributed rainfall-runoff model MIKE-SHE. Several methods were used for spatial distribution of precipitation and snow water equivalent. The model was able to simulate snow water equivalent and snowmelt timing in daily step reasonably well. Simulated discharges were slightly overestimated in later spring.

  5. Accurate modeling of spectral fine-structure in Earth radiance spectra measured with the Global Ozone Monitoring Experiment.

    PubMed

    van Deelen, Rutger; Hasekamp, Otto P; Landgraf, Jochen

    2007-01-10

    We present what we believe to be a novel approach to simulating the spectral fine structure (<1 nm) in measurements of spectrometers such as the Global Ozone Monitoring Experiment (GOME). GOME measures the Earth's radiance spectra and daily solar irradiance spectra from which a reflectivity spectrum is commonly extracted. The high-frequency structures contained in such a spectrum are, apart from atmospheric absorption, caused by Raman scattering and by a shift between the solar irradiance and the Earth's radiance spectrum. Normally, an a priori high-resolution solar spectrum is used to simulate these structures. We present an alternative method in which all the required information on the solar spectrum is retrieved from the GOME measurements. We investigate two approaches for the spectral range of 390-400 nm. First, a solar spectrum is reconstructed on a fine spectral grid from the GOME solar measurement. This approach leads to undersampling errors of up to 0.5% in the modeling of the Earth's radiance spectra. Second, a combination of the solar measurement and one of the Earth's radiance measurement is used to retrieve a solar spectrum. This approach effectively removes the undersampling error and results in residuals close to the GOME measurement noise of 0.1%.

  6. Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography

    NASA Astrophysics Data System (ADS)

    Hussey, D. S.; Spernjak, D.; Weber, A. Z.; Mukundan, R.; Fairweather, J.; Brosha, E. L.; Davey, J.; Spendelow, J. S.; Jacobson, D. L.; Borup, R. L.

    2012-11-01

    The water sorption of proton-exchange membranes (PEMs) was measured in situ using high-resolution neutron imaging in small-scale fuel cell test sections. A detailed characterization of the measurement uncertainties and corrections associated with the technique is presented. An image-processing procedure resolved a previously reported discrepancy between the measured and predicted membrane water content. With high-resolution neutron-imaging detectors, the water distributions across N1140 and N117 Nafion membranes are resolved in vapor-sorption experiments and during fuel cell and hydrogen-pump operation. The measured in situ water content of a restricted membrane at 80 °C is shown to agree with ex situ gravimetric measurements of free-swelling membranes over a water activity range of 0.5 to 1.0 including at liquid equilibration. Schroeder's paradox was verified by in situ water-content measurements which go from a high value at supersaturated or liquid conditions to a lower one with fully saturated vapor. At open circuit and during fuel cell operation, the measured water content indicates that the membrane is operating between the vapor- and liquid-equilibrated states.

  7. Finite Element Modelling of a Field-Sensed Magnetic Suspended System for Accurate Proximity Measurement Based on a Sensor Fusion Algorithm with Unscented Kalman Filter.

    PubMed

    Chowdhury, Amor; Sarjaš, Andrej

    2016-09-15

    The presented paper describes accurate distance measurement for a field-sensed magnetic suspension system. The proximity measurement is based on a Hall effect sensor. The proximity sensor is installed directly on the lower surface of the electro-magnet, which means that it is very sensitive to external magnetic influences and disturbances. External disturbances interfere with the information signal and reduce the usability and reliability of the proximity measurements and, consequently, the whole application operation. A sensor fusion algorithm is deployed for the aforementioned reasons. The sensor fusion algorithm is based on the Unscented Kalman Filter, where a nonlinear dynamic model was derived with the Finite Element Modelling approach. The advantage of such modelling is a more accurate dynamic model parameter estimation, especially in the case when the real structure, materials and dimensions of the real-time application are known. The novelty of the paper is the design of a compact electro-magnetic actuator with a built-in low cost proximity sensor for accurate proximity measurement of the magnetic object. The paper successively presents a modelling procedure with the finite element method, design and parameter settings of a sensor fusion algorithm with Unscented Kalman Filter and, finally, the implementation procedure and results of real-time operation.

  8. Finite Element Modelling of a Field-Sensed Magnetic Suspended System for Accurate Proximity Measurement Based on a Sensor Fusion Algorithm with Unscented Kalman Filter

    PubMed Central

    Chowdhury, Amor; Sarjaš, Andrej

    2016-01-01

    The presented paper describes accurate distance measurement for a field-sensed magnetic suspension system. The proximity measurement is based on a Hall effect sensor. The proximity sensor is installed directly on the lower surface of the electro-magnet, which means that it is very sensitive to external magnetic influences and disturbances. External disturbances interfere with the information signal and reduce the usability and reliability of the proximity measurements and, consequently, the whole application operation. A sensor fusion algorithm is deployed for the aforementioned reasons. The sensor fusion algorithm is based on the Unscented Kalman Filter, where a nonlinear dynamic model was derived with the Finite Element Modelling approach. The advantage of such modelling is a more accurate dynamic model parameter estimation, especially in the case when the real structure, materials and dimensions of the real-time application are known. The novelty of the paper is the design of a compact electro-magnetic actuator with a built-in low cost proximity sensor for accurate proximity measurement of the magnetic object. The paper successively presents a modelling procedure with the finite element method, design and parameter settings of a sensor fusion algorithm with Unscented Kalman Filter and, finally, the implementation procedure and results of real-time operation. PMID:27649197

  9. Accurate measurement of relative tilt and azimuth angles in electron tomography: A comparison of fiducial marker method with electron diffraction

    SciTech Connect

    Hayashida, Misa; Malac, Marek; Egerton, Ray F.; Bergen, Michael; Li, Peng

    2014-08-15

    Electron tomography is a method whereby a three-dimensional reconstruction of a nanoscale object is obtained from a series of projected images measured in a transmission electron microscope. We developed an electron-diffraction method to measure the tilt and azimuth angles, with Kikuchi lines used to align a series of diffraction patterns obtained with each image of the tilt series. Since it is based on electron diffraction, the method is not affected by sample drift and is not sensitive to sample thickness, whereas tilt angle measurement and alignment using fiducial-marker methods are affected by both sample drift and thickness. The accuracy of the diffraction method benefits reconstructions with a large number of voxels, where both high spatial resolution and a large field of view are desired. The diffraction method allows both the tilt and azimuth angle to be measured, while fiducial marker methods typically treat the tilt and azimuth angle as an unknown parameter. The diffraction method can be also used to estimate the accuracy of the fiducial marker method, and the sample-stage accuracy. A nano-dot fiducial marker measurement differs from a diffraction measurement by no more than ±1°.

  10. Accurate measurement of relative tilt and azimuth angles in electron tomography: a comparison of fiducial marker method with electron diffraction.

    PubMed

    Hayashida, Misa; Malac, Marek; Bergen, Michael; Egerton, Ray F; Li, Peng

    2014-08-01

    Electron tomography is a method whereby a three-dimensional reconstruction of a nanoscale object is obtained from a series of projected images measured in a transmission electron microscope. We developed an electron-diffraction method to measure the tilt and azimuth angles, with Kikuchi lines used to align a series of diffraction patterns obtained with each image of the tilt series. Since it is based on electron diffraction, the method is not affected by sample drift and is not sensitive to sample thickness, whereas tilt angle measurement and alignment using fiducial-marker methods are affected by both sample drift and thickness. The accuracy of the diffraction method benefits reconstructions with a large number of voxels, where both high spatial resolution and a large field of view are desired. The diffraction method allows both the tilt and azimuth angle to be measured, while fiducial marker methods typically treat the tilt and azimuth angle as an unknown parameter. The diffraction method can be also used to estimate the accuracy of the fiducial marker method, and the sample-stage accuracy. A nano-dot fiducial marker measurement differs from a diffraction measurement by no more than ±1°.

  11. Advancing Solar Irradiance Measurement for Climate-Related Studies: Accurate Constraint on Direct Aerosol Radiative Effect (DARE)

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee; Ji, Q. Jack

    2011-01-01

    Earth's climate is driven primarily by solar radiation. As summarized in various IPCC reports, the global average of radiative forcing for different agents and mechanisms, such as aerosols or CO2 doubling, is in the range of a few W/sq m. However, when solar irradiance is measured by broadband radiometers, such as the fleet of Eppley Precision Solar Pyranometers (PSP) and equivalent instrumentation employed worldwide, the measurement uncertainty is larger than 2% (e.g., WMO specification of pyranometer, 2008). Thus, out of the approx. 184 W/sq m (approx.263 W/sq m if cloud-free) surface solar insolation (Trenberth et al. 2009), the measurement uncertainty is greater than +/-3.6 W/sq m, overwhelming the climate change signals. To discern these signals, less than a 1 % measurement uncertainty is required and is currently achievable only by means of a newly developed methodology employing a modified PSP-like pyranometer and an updated calibration equation to account for its thermal effects (li and Tsay, 2010). In this talk, we will show that some auxiliary measurements, such as those from a collocated pyrgeometer or air temperature sensors, can help correct historical datasets. Additionally, we will also demonstrate that a pyrheliometer is not free of the thermal effect; therefore, comparing to a high cost yet still not thermal-effect-free "direct + diffuse" approach in measuring surface solar irradiance, our new method is more economical, and more likely to be suitable for correcting a wide variety of historical datasets. Modeling simulations will be presented that a corrected solar irradiance measurement has a significant impact on aerosol forcing, and thus plays an important role in climate studies.

  12. Integration of Error Compensation of Coordinate Measuring Machines into Feature Measurement: Part II—Experimental Implementation

    PubMed Central

    Calvo, Roque; D’Amato, Roberto; Gómez, Emilio; Domingo, Rosario

    2016-01-01

    Coordinate measuring machines (CMM) are main instruments of measurement in laboratories and in industrial quality control. A compensation error model has been formulated (Part I). It integrates error and uncertainty in the feature measurement model. Experimental implementation for the verification of this model is carried out based on the direct testing on a moving bridge CMM. The regression results by axis are quantified and compared to CMM indication with respect to the assigned values of the measurand. Next, testing of selected measurements of length, flatness, dihedral angle, and roundness features are accomplished. The measurement of calibrated gauge blocks for length or angle, flatness verification of the CMM granite table and roundness of a precision glass hemisphere are presented under a setup of repeatability conditions. The results are analysed and compared with alternative methods of estimation. The overall performance of the model is endorsed through experimental verification, as well as the practical use and the model capability to contribute in the improvement of current standard CMM measuring capabilities. PMID:27754441

  13. The development and certification of Standard Reference Materials (SRMs) to assess and ensure accurate measurement of Pb in the environment.

    PubMed

    Fassett, J D; MacDonald, B S

    2001-08-01

    The National Institute of Standards and Technology (NIST) has had a major quality-assurance role in the federal effort to reduce lead poisoning of children in the United States through its mission of ensuring the accuracy of chemical measurements. NIST certifies reference materials (standard reference materials--SRMs) that are used to benchmark measurements by secondary and field methods of analysis--to ensure that decisions of great health and economic impact are soundly based on good measurement science. Over the past 10 years, in cooperation with the US Environmental Protection Agency (EPA), US Department of Housing and Urban Development (HUD), and the United States Geological Survey (USGS), NIST has prepared and certified SRMs for lead content in soil, indoor dust, and paint. The role of these materials in meeting regulatory and abatement needs is described and their certified values are summarized.

  14. Accurate measurement of muscle belly length in the motion analysis laboratory: potential for the assessment of contracture.

    PubMed

    Fry, N R; Childs, C R; Eve, L C; Gough, M; Robinson, R O; Shortland, A P

    2003-04-01

    Two-dimensional ultrasound imaging was combined with motion analysis technology to measure distances between remote anatomical landmarks. The length of the belly of the medial gastrocnemius muscle in five normal adults (nine limbs) was estimated using this technique. Our results in vivo were similar to the reported data for the lengths of muscles in cadavers, and were consistent with the expected relationship between muscle belly length and ankle joint angle. Experiments in vitro demonstrated that the accuracy of the device was better than 2 mm over 20 cm. Measurements on the same subject on different occasions showed that the results were repeatable in vivo. Rendering of the reconstructed volume of a foam phantom gave results comparable to photographic images. This validated technique could be used to measure muscle lengths in children with spastic cerebral palsy and indicate which muscles had fixed shortening, and to what extent.

  15. Experimental measurements of the energetics of surface reactions

    NASA Astrophysics Data System (ADS)

    Campbell, Charles T.; Lytken, Ole

    2009-06-01

    Microcalorimetric measurements of the adsorption energies of well-defined surface species are reviewed, using selected examples mainly from our own group to demonstrate the types of information that can be achieved with this technique. The adsorption energies of molecules on single crystal transition metal surfaces to produce well-characterized molecular or dissociated adsorbates allow determination of the standard enthalpies of formation of key catalytic reaction intermediates. The adsorption energies for metal atoms during metal thin-film growth allow quantitative estimates of metal-substrate bond energies, metal film/substrate adhesion energies and the energetic costs associated with lattice mismatch during thin film growth. Results for several metals on MgO(1 0 0) reveal that they bind weakly to terrace sites. Metals from the right side of the periodic table also bind weakly to step and kink sites (although more strongly than on terraces), whereas alkali and alkaline earth metals bind very strongly to these defects. At 300 K, metals tend to form 2D or 3D clusters nucleated on MgO(1 0 0) defects, via a transiently adsorbed precursor (mobile adatoms on terraces). Calorimetric measurement of the energy of metal atoms in supported 3D metal nanoparticles as a function of particle size reveals a very strong size dependence below 6 nm diameter. Metal atoms also adsorb weakly on polymer surfaces and nucleate 3D metal particles, sometimes in kinetic competition with migration to and strong reaction with the more reactive, subsurface organic functional groups. Measurements of the energies for adsorbed proteins on calcium phosphate crystals, which have been structurally characterized by NMR, reveal extremely weak binding dominated by the entropy gained from release of organized water. These experimental measurements of the energies of well-defined adsorbates serve as benchmarks against which to compare theoretical computations for accuracy, thus enabling improvement upon

  16. Accurate analytical measurements in the atomic force microscope: a microfabricated spring constant standard potentially traceable to the SI

    NASA Astrophysics Data System (ADS)

    Cumpson, Peter J.; Hedley, John

    2003-12-01

    Calibration of atomic force microscope (AFM) cantilevers is necessary for the measurement of nanonewton and piconewton forces, which are critical to analytical applications of AFM in the analysis of polymer surfaces, biological structures and organic molecules at nanoscale lateral resolution. We have developed a compact and easy-to-use reference artefact for this calibration, using a method that allows traceability to the SI (Système International). Traceability is crucial to ensure that force measurements by AFM are comparable to those made by optical tweezers and other methods. The new non-contact calibration method measures the spring constant of these artefacts, by a combination of electrical measurements and Doppler velocimetry. The device was fabricated by silicon surface micromachining. The device allows AFM cantilevers to be calibrated quite easily by the 'cantilever-on-reference' method, with our reference device having a spring constant uncertainty of around ± 5% at one standard deviation. A simple substitution of the analogue velocimeter used in this work with a digital model should reduce this uncertainty to around ± 2%. Both are significant improvements on current practice, and allow traceability to the SI for the first time at these nanonewton levels.

  17. The Potential for Accurately Measuring Behavioral and Economic Dimensions of Consumption, Prices, and Markets for Illegal Drugs

    PubMed Central

    Johnson, Bruce D.; Golub, Andrew

    2007-01-01

    There are numerous analytic and methodological limitations to current measures of drug market activity. This paper explores the structure of markets and individual user behavior to provide an integrated understanding of behavioral and economic (and market) aspects of illegal drug use with an aim toward developing improved procedures for measurement. This involves understanding the social processes that structure illegal distribution networks and drug users’ interactions with them. These networks are where and how social behaviors, prices, and markets for illegal drugs intersect. Our focus is upon getting an up close measurement of these activities. Building better measures of consumption behaviors necessitates building better rapport with subjects than typically achieved with one-time surveys in order to overcome withholding and underreporting and to get a comprehensive understanding of the processes involved. This can be achieved through repeated interviews and observations of behaviors. This paper also describes analytic advances that could be adopted to direct this inquiry including behavioral templates, and insights into the economic valuation of labor inputs and cash expenditures for various illegal drugs. Additionally, the paper makes recommendations to funding organizations for developing the mechanisms that would support behavioral scientists to weigh specimens and to collect small samples for laboratory analysis—by providing protection from the potential for arrest. The primary focus is upon U.S. markets. The implications for other countries are discussed. PMID:16978801

  18. Accurate Measurements of Refractive Indices for Dielectrics in an Undergraduate Optics Laboratory for Science and Engineering Students

    ERIC Educational Resources Information Center

    Hsu, Wei-Tai; Bahrim, Cristian

    2009-01-01

    Based on our novel method recently published in the "Am. J. Phys." 77 337-43 (2009) for finding precise values of the indices of refraction for dielectrics from measurements of the polarized light reflected by the surface, in this paper we propose an improved technique for finding Brewster angles with a better precision, of 0.001 degrees, using…

  19. A Simple, Buoy Deployable Instrument for Accurate Dissolved Carbon Dioxide and Dissolved Inorganic Carbon Measurements in Freshwater and Marine Ecosystems

    NASA Astrophysics Data System (ADS)

    Browne, B. A.; Wyss, J. R.; Bowling, J. M.; Schueller, D. J.; Sherman, J. F.

    2007-05-01

    The need for better knowledge of (1) the oceanic sink for anthropogenic CO2, (2) the impact of anthropogenic CO2 on the oceanic CaCO3 system and (3) lake and stream metabolism in freshwater ecosystems is driving growing interest in real-time technologies to measure pCO2 and dissolved inorganic carbon (DIC). To be useful, these technologies must meet stringent data quality requirements of marine and freshwater biogeochemical research initiatives such as the Joint Global Ocean Flux Study, the Coral Reef Environmental Observatory Network, the National Ecological Observatory Network, and the Global Lake Ecological Observatory Network. In this presentation, we introduce new methodology and a device for unaccompanied measurement of pCO2 and DIC on research buoys or ocean/freshwater vessels. This small-scale, essentially "plug and play" device (shoe box size) has limited power requirements (≤1.8 amps) for continuous or discontinuous (e.g., one reading per hour) measurements and does not bio-foul. DIC and pCO2 can be measured in sequence using one infrared detector or in parallel using two. The accuracy and precision (<0.15% coefficient of variation) for pCO2 and DIC meet or approximate the data quality requirements for large-scale biogeochemical research initiatives. Training requirements are minimal, providing flexibility for deployments on multiple vessel types. The device works by induction of ebullition. A hydrostatic pressure drop upstream of a pump causes a temporary condition of gas oversaturation. The collection cell downstream of the pump then acts like an overpressurized soda bottle. As pressure is released within the collection cell, the dissolved gas streams passively and reliably into the infrared detector(s), at a nominal rate of 7 mL per minute, carrying CO2 into the cell essentially at its in-situ partial pressure. To measure DIC, a valve allows for the addition of acid to the sampling line upstream of the pump converting all DIC to CO2 prior to reaching

  20. Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere

    NASA Astrophysics Data System (ADS)

    Volten, H.; Bergwerff, J. B.; Haaima, M.; Lolkema, D. E.; Berkhout, A. J. C.; van der Hoff, G. R.; Potma, C. J. M.; Wichink Kruit, R. J.; van Pul, W. A. J.; Swart, D. P. J.

    2012-02-01

    We present two Differential Optical Absorption Spectroscopy (DOAS) instruments built at RIVM: the RIVM DOAS and the miniDOAS. Both instruments provide virtually interference-free measurements of NH3 concentrations in the atmosphere, since they measure over an open path, without suffering from inlet problems or interference problems by ammonium aerosols dissociating on tubes or filters. They measure concentrations up to at least 200 μg m-3, have a fast response, low maintenance demands, and a high up-time. The RIVM DOAS has a high accuracy of typically 0.15 μg m-3 for ammonia for 5-min averages and over a total light path of 100 m. The miniDOAS has been developed for application in measurement networks such as the Dutch National Air Quality Monitoring Network (LML). Compared to the RIVM DOAS it has a similar accuracy, but is significantly reduced in size, costs, and handling complexity. The RIVM DOAS and miniDOAS results showed excellent agreement (R2 = 0.996) during a field measurement campaign in Vredepeel, the Netherlands. This measurement site is located in an agricultural area and is characterized by highly variable, but on average high ammonia concentrations in the air. The RIVM-DOAS and miniDOAS results were compared to the results of the AMOR instrument, a continuous-flow wet denuder system, which is currently used in the LML. Averaged over longer time spans of typically a day, the (mini)DOAS and AMOR results agree reasonably well, although an offset of the AMOR values compared to the (mini)DOAS results exists. On short time scales, the (mini)DOAS shows a faster response and does not show the memory effects due to inlet tubing and transport of absorption fluids encountered by the AMOR. Due to its high accuracy, high uptime, low maintenance and its open path, the (mini)DOAS shows a good potential for flux measurements by using two (or more) systems in a gradient set-up and applying the aerodynamic gradient technique.

  1. Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere

    NASA Astrophysics Data System (ADS)

    Volten, H.; Bergwerff, J. B.; Haaima, M.; Lolkema, D. E.; Berkhout, A. J. C.; van der Hoff, G. R.; Potma, C. J. M.; Wichink Kruit, R. J.; van Pul, W. A. J.; Swart, D. P. J.

    2011-08-01

    We present two Differential Optical Absorption Spectroscopy (DOAS) instruments built at RIVM, the RIVM DOAS and the miniDOAS. Both instruments provide virtually interference free measurements of NH3 concentrations in the atmosphere, since they measure over an open path, without suffering from inlet problems or interference problems by ammonium aerosols dissociating on tubes or filters. They measure concentrations up to at least 200 μg m-3, have a fast response, low maintenance demands, and a high up-time. The RIVM DOAS has a high accuracy of typically 0.15 μg m-3 for ammonia over 5-min averages and over a total light path of 100 m. The miniDOAS has been developed for application in measurement networks such as the Dutch National Air Quality Monitoring Network (LML). Compared to the RIVM DOAS it has a similar accuracy, but is significantly reduced in size, costs, and handling complexity. The RIVM DOAS and miniDOAS results showed excellent agreement (R2 = 0.996) during a field measurement campaign in Vredepeel, the Netherlands. This measurement site is located in an agricultural area and is characterized by highly variable, but on average high ammonia concentrations in the air. The RIVM-DOAS and miniDOAS results were compared to the results of the AMOR instrument, a continuous-flow wet denuder system, which is currently used in the LML. Averaged over longer time spans of typically a day the (mini)DOAS and AMOR results agree reasonably well, although an offset of the AMOR values compared to the (mini)DOAS results exists. On short time scales the (mini)DOAS shows a faster response and does not show the memory effects due to inlet tubing and transport of absorption fluids encountered by the AMOR. Due to its high accuracy, high uptime, low maintenance and its open path, the (mini)DOAS shows a good potential for flux measurements by using two (or more) systems in a gradient set-up and applying the aerodynamic gradient technique.

  2. Accurately measuring sea level change from space: an ESA Climate Change Initiative for MSL closure budget studies

    NASA Astrophysics Data System (ADS)

    Legeais, JeanFrancois; Cazenave, Anny; Ablain, Michael; Larnicol, Gilles; Benveniste, Jerome; Johannessen, Johnny; Timms, Gary; Andersen, Ole; Cipollini, Paolo; Roca, Monica; Rudenko, Sergei; Fernandes, Joana; Balmaseda, Magdalena; Quartly, Graham; Fenoglio-Marc, Luciana; Meyssignac, Benoit; Scharffenberg, Martin

    2016-04-01

    Sea level is a very sensitive index of climate change and variability. Sea level integrates the ocean warming, mountain glaciers and ice sheet melting. Understanding the sea level variability and changes implies an accurate monitoring of the sea level variable at climate scales, in addition to understanding the ocean variability and the exchanges between ocean, land, cryosphere, and atmosphere. That is why Sea Level is one of the Essential Climate Variables (ECV) selected in the frame of the ESA Climate Change Initiative (CCI) program. It aims at providing long-term monitoring of the sea level ECV with regular updates, as required for climate studies. The program is now in its second phase of 3 year (following phase I during 2011-2013). The objectives are firstly to involve the climate research community, to refine their needs and collect their feedbacks on product quality. And secondly to develop, test and select the best algorithms and standards to generate an updated climate time series and to produce and validate the Sea Level ECV product. This will better answer the climate user needs by improving the quality of the Sea Level products and maintain a sustain service for an up-to-date production. This has led to the production of the Sea Level ECV which has benefited from yearly extensions and now covers the period 1993-2014. We will firstly present the main achievements of the ESA CCI Sea Level Project. On the one hand, the major steps required to produce the 22 years climate time series are briefly described: collect and refine the user requirements, development of adapted algorithms for climate applications and specification of the production system. On the other hand, the product characteristics are described as well as the results from product validation, performed by several groups of the ocean and climate modeling community. At last, new altimeter standards have been developed and the best one have been recently selected in order to produce a full

  3. Accurately measuring sea level change from space: an ESA climate change initiative for MSL closure budget studies

    NASA Astrophysics Data System (ADS)

    Legeais, JeanFrancois; Benveniste, Jérôme

    2016-07-01

    Sea level is a very sensitive index of climate change and variability. Sea level integrates the ocean warming, mountain glaciers and ice sheet melting. Understanding the sea level variability and changes implies an accurate monitoring of the sea level variable at climate scales, in addition to understanding the ocean variability and the exchanges between ocean, land, cryosphere, and atmosphere. That is why Sea Level is one of the Essential Climate Variables (ECV) selected in the frame of the ESA Climate Change Initiative (CCI) program. It aims at providing long-term monitoring of the sea level ECV with regular updates, as required for climate studies. The program is now in its second phase of 3 year (following phase I during 2011-2013). The objectives are firstly to involve the climate research community, to refine their needs and collect their feedbacks on product quality. And secondly to develop, test and select the best algorithms and standards to generate an updated climate time series and to produce and validate the Sea Level ECV product. This will better answer the climate user needs by improving the quality of the Sea Level products and maintain a sustain service for an up-to-date production. This has led to the production of a first version of the Sea Level ECV which has benefited from yearly extensions and now covers the period 1993-2014. Within phase II, new altimeter standards have been developed and tested in order to reprocess the dataset with the best standards for climate studies. The reprocessed ECV will be released in summer 2016. We will present the main achievements of the ESA CCI Sea Level Project. On the one hand, the major steps required to produce the 22 years climate time series are briefly described: collect and refine the user requirements, development of adapted algorithms for climate applications and specification of the production system. On the other hand, the product characteristics are described as well as the results from product

  4. Alfvénic oscillations of the electron distribution function: Linear theory and experimental measurements

    SciTech Connect

    Schroeder, J. W. R. Skiff, F.; Howes, G. G.; Kletzing, C. A.; Carter, T. A.; Dorfman, S.

    2015-12-10

    Wave propagation can be an accurate method for determining material properties. High frequency whistler mode waves (0.7 < ω/|Ω{sub ce}| < 1) in an overdense plasma (ω{sub pe} > |Ω{sub ce}|) are damped primarily by Doppler-shifted electron cyclotron resonance. A kinetic description of whistler mode propagation parallel to the background magnetic field shows that damping is proportional to the parallel electron distribution function. This property enables an experimental determination of the parallel electron distribution function using a measurement of whistler mode wave absorption. The whistler mode wave absorption diagnostic uses this technique on UCLA’s Large Plasma Device (LaPD) to measure the distribution of high energy electrons (5 − 10v{sub te}) with 0.1% precision. The accuracy is limited by systematic effects that need to be considered carefully. Ongoing research uses this diagnostic to investigate the effect of inertial Alfvén waves on the electron distribution function. Results presented here verify experimentally the linear effects of inertial Alfvén waves on the reduced electron distribution function, a necessary step before nonlinear physics can be tested. Ongoing experiments with the whistler mode wave absorption diagnostic are making progress toward the first direct detection of electrons nonlinearly accelerated by inertial Alfvén waves, a process believed to play an important role in auroral generation.

  5. The readout of the LHC beam luminosity monitor: Accurate shower energy measurements at a 40 MHz repetition rate

    SciTech Connect

    Manfredi, P.F.; Ratti, L.; Speziali, V.; Traversi, G.; Manghisoni, M.; Re, V.; Denes, P.; Placidi, M.; Ratti, A.; Turner, W.C.; Datte, P.S.; Millaud, J.E.

    2003-05-10

    The LHC beam luminosity monitor is based on the following principle. The neutrals that originate in LHC at every PP interaction create showers in the absorbers placed in front of the cryogenic separation dipoles. The shower energy, as it can be measured by suitable detectors in the absorbers is proportional to the number of neutral particles and, therefore, to the luminosity. This principle lends itself to a luminosity measurement on a bunch-by-bunch basis. However, detector and front-end electronics must comply with extremely stringent requirements. To make the bunch-by-bunch measurement feasible, their speed of operation must match the 40 MHz bunch repetition rate of LHC. Besides, in the actual operation the detector must stand extremely high radiation doses. The front-end electronics, to survive, must be located at some distance from the region of high radiation field, which means that a properly terminated, low-noise, cable connection is needed between detector and front-end electronics. After briefly reviewing the solutions that have been adopted for the detector and the front-end electronics and the results that have been obtained so far in tests on the beam, the latest version of the instrument in describe in detail. It will be shown how a clever detector design, a suitable front-end conception based on the use of a ''cold resistance'' cable termination and a careful low-noise design, along with the use of an effective deconvolution algorithm, make the luminosity measurement possible on a bunch-by-bunch basis at the LHC bunch repetition rates.

  6. Instrumentation and key elements of the dispersive x-ray absorption spectrometer for accurate measurements (invited) (abstract)

    NASA Astrophysics Data System (ADS)

    Fontaine, A.; Baudelet, F.; Dartyge, E.; Dubuisson, J. M.; Giorgetti, C.; Pizzini, Stefania; Andrault, D.; Farges, F.; Fiquet, G.; Itié, J. P.; Polian, A.; Miguel, A. San; Tolentino, H.

    1995-02-01

    Measurement of very small differences of the total cross section is the current demand for the spectrometers dedicated to time-dependent experiments carried out under various time-ramped parameters. The dispersive optics and more precisely the full x-ray-absorption spectrometer is mechanically movement-free during data collection which can last over 12 h at LURE-DCI to be sensitive to relative change of the absorption of the order of 10-5. In this range, artefacts due to the drift of silicon lattice spacing under temperature change of the crystal, and drifts of the detector position because of liquid-nitrogen evaporation contained in the cryostat, are sources of errors which have been identified and cured or ... by-passed. The accuracy in difference measurements is now of the order of 10-5 for a total cross section measured equal to 1. In term of optics stability a difference signal of 10-4 out of 1 can be generated by an absorption edge shift caused by a 0.05 K drift of the temperature of the silicon crystal at 7 keV. These performances are essential for the measurement of XMCD in the hard-x-ray range. Water cooling of the dynamically bent crystal reduces dramatically the change of the Si temperature. Adequate geometry makes the spatial drift of the position of the photodiode array much less concerning. The focusing efficiency is also a key parameter to push high-pressure x-ray-absorption spectroscopy (55 GPa), and high-temperature XAS (2000 K), and the combination (15 GPa, 800 K). Simple devices, taking advantage of the focusing geometry, have been successfully tested these last two years.

  7. How accurately can we measure the hydrogen 2S→1S transition rate from the cosmological data?

    SciTech Connect

    Mukhanov, Viatcheslav; Kim, Jaiseung; Naselsky, Pavel; Trombetti, Tiziana; Burigana, Carlo E-mail: jkim@nbi.dk E-mail: trombetti@iasfbo.inaf.it

    2012-06-01

    Recent progress in observational cosmology, and especially the forthcoming PLANCK mission data, open new directions in so-called precision cosmology. In this paper we illustrate this statement considering the accuracy of cosmological determination of the two-quanta decay rate of 2s hydrogen atom state. We show that the PLANCK data will allow us to measure this decay rate significantly better than in the laboratory experiments.

  8. A new interpretation of electrochemical impedance spectroscopy to measure accurate doping levels for conducting polymers: Separating Faradaic and capacitive currents

    NASA Astrophysics Data System (ADS)

    Ulgut, Burak; Grose, Jacob E.; Kiya, Yasuyuki; Ralph, Daniel C.; Abruña, Héctor D.

    2009-12-01

    We report an electrochemical impedance spectroscopy (EIS) based method to measure the doping level of conducting polymers. Using EIS the Faradaic current and the capacitive charging current can be separated without relying on any unverifiable assumptions. We demonstrate the method for three types of conducting polymer thin films that are the basis for many commercial applications (poly(3,4-ethylenedioxythiophene), poly-3-hexylthiophene and polypyrrole).

  9. Improving the sampling technique of arterialized capillary samples to obtain more accurate PaO2 measurements.

    PubMed

    Wimpress, S; Vara, D D; Brightling, C E

    2005-01-01

    Arterialized earlobe capillary blood samples (ELCS) have been used as a measurement of blood gas status for over 20 years. There is general acceptance that there is a strong correlation and limits of agreement between arterial and arterialized blood samples with respect to pH and PaCO2. Although the correlation between the arterial and arterialized PaO2 is good, the limits of agreement poor. Our aim was to improve the accuracy of this technique in the measurement of PaO2 by simultaneously monitoring the oxygen saturation by pulse oximetry whilst taking an ELCS. We hypothesize that significant discrepancies between the SaO2 and SpO2 highlight either a poorly arterialized sample or an over aerated sample from air bubbles. We compared the SpO2 with the SaO2 of an arterial sample from 27 inpatients. We used the limits of agreement between these samples to define the degree of discordance we would accept between SaO2 and SpO2 before repeat ELCS. Subsequently, 252 consecutive patients attending our respiratory physiology unit over a six-month period had an ELCS and simultaneous SpO2. If there was a discrepancy between SaO2 and SpO2 of > 2% the ELCS was repeated. There was a good correlation and limits of agreement between the SpO2 and arterial SaO2 (r = 0.97, mean difference +/- 95% limits of agreement: 0.34 +/- 2.68). A difference of more than 2% between arterialized SaO2 and SpO2 was identified in 21 patients out of 252 (8.3%) with SaO2 higher in two and lower in 19 (r = 0.96, mean difference +/- 95% limits of agreement: 0.66 +/- 3.1). Repeat ELCS of these 21 samples reduced this discrepancy improving the concordance of the measurements (r = 0.98, mean difference +/- 95% limits of agreement: 0.47 +/- 1.0). In one case a difference of 3% remained between the saturations. We conclude that the addition of simultaneous pulse oximetry with ELCS will identify rogue measurements in about 8% of cases highlighting the need for repeat samples and thus increasing the accuracy of

  10. Accurate and stable equal-pressure measurements of water vapor transmission rate reaching the 10−6 g m−2 day−1 range

    PubMed Central

    Nakano, Yoichiro; Yanase, Takashi; Nagahama, Taro; Yoshida, Hajime; Shimada, Toshihiro

    2016-01-01

    The water vapor transmission rate (WVTR) of a gas barrier coating is a critically important parameter for flexible organic device packaging, but its accurate measurement without mechanical stress to ultrathin films has been a significant challenge in instrumental analysis. At the current stage, no reliable results have been reported in the range of 10−6 g m−2 day−1 that is required for organic light emitting diodes (OLEDs). In this article, we describe a solution for this difficult, but important measurement, involving enhanced sensitivity by a cold trap, stabilized temperature system, pumped sealing and calibration by a standard conductance element. PMID:27748431

  11. Accurate and stable equal-pressure measurements of water vapor transmission rate reaching the 10(-6) g m(-2) day(-1) range.

    PubMed

    Nakano, Yoichiro; Yanase, Takashi; Nagahama, Taro; Yoshida, Hajime; Shimada, Toshihiro

    2016-10-17

    The water vapor transmission rate (WVTR) of a gas barrier coating is a critically important parameter for flexible organic device packaging, but its accurate measurement without mechanical stress to ultrathin films has been a significant challenge in instrumental analysis. At the current stage, no reliable results have been reported in the range of 10(-6) g m(-2) day(-1) that is required for organic light emitting diodes (OLEDs). In this article, we describe a solution for this difficult, but important measurement, involving enhanced sensitivity by a cold trap, stabilized temperature system, pumped sealing and calibration by a standard conductance element.

  12. Accurate and stable equal-pressure measurements of water vapor transmission rate reaching the 10‑6 g m‑2 day‑1 range

    NASA Astrophysics Data System (ADS)

    Nakano, Yoichiro; Yanase, Takashi; Nagahama, Taro; Yoshida, Hajime; Shimada, Toshihiro

    2016-10-01

    The water vapor transmission rate (WVTR) of a gas barrier coating is a critically important parameter for flexible organic device packaging, but its accurate measurement without mechanical stress to ultrathin films has been a significant challenge in instrumental analysis. At the current stage, no reliable results have been reported in the range of 10‑6 g m‑2 day‑1 that is required for organic light emitting diodes (OLEDs). In this article, we describe a solution for this difficult, but important measurement, involving enhanced sensitivity by a cold trap, stabilized temperature system, pumped sealing and calibration by a standard conductance element.

  13. The Cambridge Face Tracker: Accurate, Low Cost Measurement of Head Posture Using Computer Vision and Face Recognition Software

    PubMed Central

    Thomas, Peter B. M.; Baltrušaitis, Tadas; Robinson, Peter; Vivian, Anthony J.

    2016-01-01

    Purpose We validate a video-based method of head posture measurement. Methods The Cambridge Face Tracker uses neural networks (constrained local neural fields) to recognize facial features in video. The relative position of these facial features is used to calculate head posture. First, we assess the accuracy of this approach against videos in three research databases where each frame is tagged with a precisely measured head posture. Second, we compare our method to a commercially available mechanical device, the Cervical Range of Motion device: four subjects each adopted 43 distinct head postures that were measured using both methods. Results The Cambridge Face Tracker achieved confident facial recognition in 92% of the approximately 38,000 frames of video from the three databases. The respective mean error in absolute head posture was 3.34°, 3.86°, and 2.81°, with a median error of 1.97°, 2.16°, and 1.96°. The accuracy decreased with more extreme head posture. Comparing The Cambridge Face Tracker to the Cervical Range of Motion Device gave correlation coefficients of 0.99 (P < 0.0001), 0.96 (P < 0.0001), and 0.99 (P < 0.0001) for yaw, pitch, and roll, respectively. Conclusions The Cambridge Face Tracker performs well under real-world conditions and within the range of normally-encountered head posture. It allows useful quantification of head posture in real time or from precaptured video. Its performance is similar to that of a clinically validated mechanical device. It has significant advantages over other approaches in that subjects do not need to wear any apparatus, and it requires only low cost, easy-to-setup consumer electronics. Translational Relevance Noncontact assessment of head posture allows more complete clinical assessment of patients, and could benefit surgical planning in future. PMID:27730008

  14. Functional connectivity and structural covariance between regions of interest can be measured more accurately using multivariate distance correlation.

    PubMed

    Geerligs, Linda; Cam-Can; Henson, Richard N

    2016-07-15

    Studies of brain-wide functional connectivity or structural covariance typically use measures like the Pearson correlation coefficient, applied to data that have been averaged across voxels within regions of interest (ROIs). However, averaging across voxels may result in biased connectivity estimates when there is inhomogeneity within those ROIs, e.g., sub-regions that exhibit different patterns of functional connectivity or structural covariance. Here, we propose a new measure based on "distance correlation"; a test of multivariate dependence of high dimensional vectors, which allows for both linear and non-linear dependencies. We used simulations to show how distance correlation out-performs Pearson correlation in the face of inhomogeneous ROIs. To evaluate this new measure on real data, we use resting-state fMRI scans and T1 structural scans from 2 sessions on each of 214 participants from the Cambridge Centre for Ageing & Neuroscience (Cam-CAN) project. Pearson correlation and distance correlation showed similar average connectivity patterns, for both functional connectivity and structural covariance. Nevertheless, distance correlation was shown to be 1) more reliable across sessions, 2) more similar across participants, and 3) more robust to different sets of ROIs. Moreover, we found that the similarity between functional connectivity and structural covariance estimates was higher for distance correlation compared to Pearson correlation. We also explored the relative effects of different preprocessing options and motion artefacts on functional connectivity. Because distance correlation is easy to implement and fast to compute, it is a promising alternative to Pearson correlations for investigating ROI-based brain-wide connectivity patterns, for functional as well as structural data.

  15. Role of Photoexcitation and Field Ionization in the Measurement of Accurate Oxide Stoichiometry by Laser-Assisted Atom Probe Tomography

    SciTech Connect

    Devaraj, Arun; Colby, Robert J.; Hess, Wayne P.; Perea, Daniel E.; Thevuthasan, Suntharampillai

    2013-03-06

    Pulsed lasers extend the high spatial and mass resolution of atom probe tomography (APT) to non-conducting materials, such as oxides. For prototypical metal oxide MgO, measured stoichiometry depends strongly upon pulse energy and applied voltage. Very low laser energies (0.02 pJ) and high electric fields yield optimal stoichiometric accuracy, attributed to the field-dependent ionization of photo-desorbed O or O2 neutrals. This emphasizes the importance of considering electronic excitations in APT analysis of oxides ionic materials.

  16. Statistical analysis of accurate prediction of local atmospheric optical attenuation with a new model according to weather together with beam wandering compensation system: a season-wise experimental investigation

    NASA Astrophysics Data System (ADS)

    Arockia Bazil Raj, A.; Padmavathi, S.

    2016-07-01

    Atmospheric parameters strongly affect the performance of Free Space Optical Communication (FSOC) system when the optical wave is propagating through the inhomogeneous turbulent medium. Developing a model to get an accurate prediction of optical attenuation according to meteorological parameters becomes significant to understand the behaviour of FSOC channel during different seasons. A dedicated free space optical link experimental set-up is developed for the range of 0.5 km at an altitude of 15.25 m. The diurnal profile of received power and corresponding meteorological parameters are continuously measured using the developed optoelectronic assembly and weather station, respectively, and stored in a data logging computer. Measured meteorological parameters (as input factors) and optical attenuation (as response factor) of size [177147 × 4] are used for linear regression analysis and to design the mathematical model that is more suitable to predict the atmospheric optical attenuation at our test field. A model that exhibits the R2 value of 98.76% and average percentage deviation of 1.59% is considered for practical implementation. The prediction accuracy of the proposed model is investigated along with the comparative results obtained from some of the existing models in terms of Root Mean Square Error (RMSE) during different local seasons in one-year period. The average RMSE value of 0.043-dB/km is obtained in the longer range dynamic of meteorological parameters variations.

  17. Is a standalone inertial measurement unit accurate and precise enough for quantification of movement symmetry in the horse?

    PubMed

    Brighton, Charlotte; Olsen, Emil; Pfau, Thilo

    2015-01-01

    Standalone 'low-cost' inertial measurement units (IMUs) could facilitate large-scale studies into establishing minimal important differences (MID) for orthopaedic deficits (lameness) in horses. We investigated accuracy and limits of agreement (LoA) after correction of magnitude-dependent differences of a standalone 6 degree-of-freedom IMU compared with an established IMU-based gait analysis system (MTx) in six horses for two anatomical landmarks (sacrum and sternum). Established symmetry measures were calculated from vertical displacement: symmetry index (SI), difference between minima (MinDiff) and difference between maxima (MaxDiff). For the sacrum, LoA were ± 0.095 for SI, ± 6.6 mm for MinDiff and ± 4.3 mm for MaxDiff. For the sternum, LoA values were ± 0.088 for SI, ± 5.0 mm for MinDiff and ± 4.2 mm for MaxDiff. Compared with reference data from mildly lame horses, SI values indicate sufficient precision, whereas MinDiff and MaxDiff values are less favourable. Future studies should investigate specific calibration and processing algorithms further improving standalone IMU performance.

  18. ‘Dose-to-Mother’ Deuterium Oxide Dilution Technique: An Accurate Strategy to Measure Vitamin A Intake in Breastfed Infants

    PubMed Central

    Lopez-Teros, Veronica; Limon-Miro, Ana Teresa; Astiazaran-Garcia, Humberto; Tanumihardjo, Sherry A.; Tortoledo-Ortiz, Orlando; Valencia, Mauro E.

    2017-01-01

    In Mexico, infants (0–2 years old) show the highest prevalence of vitamin A deficiency (VAD), measured by serum retinol concentrations. Thus, we consider that low vitamin A (VA) intake through breast milk (BM) combined with poor weaning practices are the main factors that contribute to VAD in this group. We combined the assessment of VA status in lactating women using BM retinol and a stable isotope ‘dose-to-mother’ technique to measure BM production in women from urban and agricultural areas. Infants’ mean BM intake was 758 ± 185 mL, and no difference was observed between both areas (p = 0.067). Mean BM retinol concentration was 1.09 μmol/L, which was significantly lower for the agricultural area (p = 0.028). Based on BM retinol concentration, 57% of women were VAD; although this prevalence fell to 16% when based on fat content. Regardless of the VA biomarker used here, infants from the urban and agricultural areas cover only 66% and 49% of their dietary adequate intake from BM, respectively (p = 0.054). Our data indicate that VAD is still a public health concern in Mexico. Adopting both methods to assess VA transfer from the mother to the breastfed child offers an innovative approach towards the nutritional assessment of vulnerable groups. PMID:28230781

  19. Determination of accurate protein monoisotopic mass with the most abundant mass measurable using high-resolution mass spectrometry.

    PubMed

    Chen, Ya-Fen; Chang, C Allen; Lin, Yu-Hsuan; Tsay, Yeou-Guang

    2013-09-01

    While recent developments in mass spectrometry enable direct evaluation of monoisotopic masses (M(mi)) of smaller compounds, protein M(mi) is mostly determined based on its relationship to average mass (Mav). Here, we propose an alternative approach to determining protein M(mi) based on its correlation with the most abundant mass (M(ma)) measurable using high-resolution mass spectrometry. To test this supposition, we first empirically calculated M(mi) and M(ma) of 6158 Escherichia coli proteins, which helped serendipitously uncover a linear correlation between these two protein masses. With the relationship characterized, liquid chromatography-mass spectrometry was employed to measure M(ma) of protein samples in its ion cluster with the highest signal in the mass spectrum. Generally, our method produces a short series of likely M(mi) in 1-Da steps, and the probability of each likely M(mi) is assigned statistically. It is remarkable that the mass error of this M(mi) is as miniscule as a few parts per million, indicating that our method is capable of determining protein M(mi) with high accuracy. Benefitting from the outstanding performance of modern mass spectrometry, our approach is a significant improvement over others and should be of great utility in the rapid assessment of protein primary structures.

  20. Accurate measurements of vadose zone fluxes using automated equilibrium tension plate lysimeters: A synopsis of results from the Spydia research facility, New Zealand.

    NASA Astrophysics Data System (ADS)

    Wöhling, Thomas; Barkle, Greg; Stenger, Roland; Moorhead, Brian; Wall, Aaron; Clague, Juliet

    2014-05-01

    Automated equilibrium tension plate lysimeters (AETLs) are arguably the most accurate method to measure unsaturated water and contaminant fluxes below the root zone at the scale of up to 1 m². The AETL technique utilizes a porous sintered stainless-steel plate to provide a comparatively large sampling area with a continuously controlled vacuum that is in "equilibrium" with the surrounding vadose zone matric pressure to ensure measured fluxes represent those under undisturbed conditions. This novel lysimeter technique was used at an intensive research site for investigations of contaminant pathways from the land surface to the groundwater on a sheep and beef farm under pastoral land use in the Tutaeuaua subcatchment, New Zealand. The Spydia research facility was constructed in 2005 and was fully operational between 2006 and 2011. Extending from a central access caisson, 15 separately controlled AETLs with 0.2 m² surface area were installed at five depths between 0.4 m and 5.1 m into the undisturbed volcanic vadose zone materials. The unique setup of the facility ensured minimum interference of the experimental equipment and external factors with the measurements. Over the period of more than five years, a comprehensive data set was collected at each of the 15 AETL locations which comprises of time series of soil water flux, pressure head, volumetric water contents, and soil temperature. The soil water was regularly analysed for EC, pH, dissolved carbon, various nitrogen compounds (including nitrate, ammonia, and organic N), phosphorus, bromide, chloride, sulphate, silica, and a range of other major ions, as well as for various metals. Climate data was measured directly at the site (rainfall) and a climate station at 500m distance. The shallow groundwater was sampled at three different depths directly from the Spydia caisson and at various observation wells surrounding the facility. Two tracer experiments were conducted at the site in 2009 and 2010. In the 2009

  1. Autonomous Instrumentation for Fast, Continuous and Accurate Isotopic Measurements of Water Vapor (δ18O, δ 2H, H2O) in the Field

    NASA Astrophysics Data System (ADS)

    Liem, J. S.; Dong, F.; Owano, T. G.; Baer, D. S.

    2010-12-01

    Stable isotopes of water vapor are powerful tracers to investigate the hydrological cycle and ecological processes. Therefore, continuous, in-situ and accurate measurements of δ18O and δ2H are critical to advance the understanding of water-cycle dynamics worldwide. Furthermore, the combination of meteorological techniques and high-frequency isotopic water measurements can provide detailed time-resolved information on the eco-physiological performance of plants and enable improved understanding of water fluxes at ecosystem scales. In this work, we present recent development and field deployment of a novel Water Vapor Isotope Measurement System (WVIMS) capable of simultaneous in situ measurements of δ18O and δ2H and water mixing ratio (H2O) with high precision, accuracy and speed (up to 10 Hz measurement rate). The WVIMS consists of an Analyzer (Water Vapor Isotope Analyzer), based on cavity enhanced laser absorption spectroscopy, and a Standard Source (Water Vapor Isotope Standard Source), based on quantitative evaporation of a liquid water standard (with known isotopic content), and operates in a dual-inlet configuration. The WVIMS automatically controls the entire sample and data collection, data analysis and calibration process to allow for continuous, autonomous unattended long-term operation. The WVIMS has been demonstrated for accurate (i.e. fully calibrated) measurements ranging from 500 ppmv (typical of arctic environments) to over 30,000 ppmv (typical of tropical environments) in air. Dual-inlet operation, which involves regular calibration with isotopic water vapor reference standards, essentially eliminates measurement drift, ensures data reliability, and allows operation over an extremely wide ambient temperature range (5-45C). This presentation will include recent measurements recorded using the WVIMS in plant growth chambers and in arctic environments. The availability of this new instrumentation provides new opportunities for detailed continuous

  2. A time domain based method for the accurate measurement of Q-factor and resonance frequency of microwave resonators

    SciTech Connect

    Gyüre, B.; Márkus, B. G.; Bernáth, B.; Simon, F.; Murányi, F.

    2015-09-15

    We present a novel method to determine the resonant frequency and quality factor of microwave resonators which is faster, more stable, and conceptually simpler than the yet existing techniques. The microwave resonator is pumped with the microwave radiation at a frequency away from its resonance. It then emits an exponentially decaying radiation at its eigen-frequency when the excitation is rapidly switched off. The emitted microwave signal is down-converted with a microwave mixer, digitized, and its Fourier transformation (FT) directly yields the resonance curve in a single shot. Being a FT based method, this technique possesses the Fellgett (multiplex) and Connes (accuracy) advantages and it conceptually mimics that of pulsed nuclear magnetic resonance. We also establish a novel benchmark to compare accuracy of the different approaches of microwave resonator measurements. This shows that the present method has similar accuracy to the existing ones, which are based on sweeping or modulating the frequency of the microwave radiation.

  3. A time domain based method for the accurate measurement of Q-factor and resonance frequency of microwave resonators

    NASA Astrophysics Data System (ADS)

    Gyüre, B.; Márkus, B. G.; Bernáth, B.; Murányi, F.; Simon, F.

    2015-09-01

    We present a novel method to determine the resonant frequency and quality factor of microwave resonators which is faster, more stable, and conceptually simpler than the yet existing techniques. The microwave resonator is pumped with the microwave radiation at a frequency away from its resonance. It then emits an exponentially decaying radiation at its eigen-frequency when the excitation is rapidly switched off. The emitted microwave signal is down-converted with a microwave mixer, digitized, and its Fourier transformation (FT) directly yields the resonance curve in a single shot. Being a FT based method, this technique possesses the Fellgett (multiplex) and Connes (accuracy) advantages and it conceptually mimics that of pulsed nuclear magnetic resonance. We also establish a novel benchmark to compare accuracy of the different approaches of microwave resonator measurements. This shows that the present method has similar accuracy to the existing ones, which are based on sweeping or modulating the frequency of the microwave radiation.

  4. Experimental measurement of ablation effects in plasma armature railguns

    SciTech Connect

    Parker, J.V.; Parsons, W.M.

    1986-01-01

    Experimental evidence supporting the importance of ablation in plasma armature railguns is presented. Experiments conducted using the HYVAX and MIDI-2 railguns are described. Several indirect effects of ablation are identified from the experimental results. An improved ablation model of plasma armature dynamics is proposed which incorporates the restrike process.

  5. Accurate Measurements of the Skin Surface Area of the Healthy Auricle and Skin Deficiency in Microtia Patients

    PubMed Central

    van Doremalen, Rob F. M.; Melchels, Ferry P. W.; Kolodzynski, Michail N.; Pouran, Behdad; Malda, Jos; Kon, Moshe; Breugem, Corstiaan C.

    2016-01-01

    Background: The limited cranial skin covering auricular implants is an important yet underrated factor in auricular reconstruction for both reconstruction surgery and tissue engineering strategies. We report exact measurements on skin deficiency in microtia patients and propose an accessible preoperative method for these measurements. Methods: Plaster ear models (n = 11; male:female = 2:1) of lobular-type microtia patients admitted to the University Medical Center Utrecht in The Netherlands were scanned using a micro-computed tomographic scanner or a cone-beam computed tomographic scanner. The resulting images were converted into mesh models from which the surface area could be calculated. Results: The mean total skin area of an adult-size healthy ear was 47.3 cm2, with 49.0 cm2 in men and 44.3 cm2 in women. Microtia ears averaged 14.5 cm2, with 15.6 cm2 in men and 12.6 cm2 in women. The amount of skin deficiency was 25.4 cm2, with 26.7 cm2 in men and 23.1 cm2 in women. Conclusions: This study proposes a novel method to provide quantitative data on the skin surface area of the healthy adult auricle and the amount of skin deficiency in microtia patients. We demonstrate that the microtia ear has less than 50% of skin available compared with healthy ears. Limited skin availability in microtia patients can lead to healing problems after auricular reconstruction and poses a significant challenge in the development of tissue-engineered cartilage implants. The results of this study could be used to evaluate outcomes and investigate new techniques with regard to tissue-engineered auricular constructs. PMID:28293505

  6. How many measurements are needed to estimate accurate daily and annual soil respiration fluxes? Analysis using data from a temperate rainforest

    NASA Astrophysics Data System (ADS)

    Perez-Quezada, Jorge F.; Brito, Carla E.; Cabezas, Julián; Galleguillos, Mauricio; Fuentes, Juan P.; Bown, Horacio E.; Franck, Nicolás

    2016-12-01

    Making accurate estimations of daily and annual Rs fluxes is key for understanding the carbon cycle process and projecting effects of climate change. In this study we used high-frequency sampling (24 measurements per day) of Rs in a temperate rainforest during 1 year, with the objective of answering the questions of when and how often measurements should be made to obtain accurate estimations of daily and annual Rs. We randomly selected data to simulate samplings of 1, 2, 4 or 6 measurements per day (distributed either during the whole day or only during daytime), combined with 4, 6, 12, 26 or 52 measurements per year. Based on the comparison of partial-data series with the full-data series, we estimated the performance of different partial sampling strategies based on bias, precision and accuracy. In the case of annual Rs estimation, we compared the performance of interpolation vs. using non-linear modelling based on soil temperature. The results show that, under our study conditions, sampling twice a day was enough to accurately estimate daily Rs (RMSE < 10 % of average daily flux), even if both measurements were done during daytime. The highest reduction in RMSE for the estimation of annual Rs was achieved when increasing from four to six measurements per year, but reductions were still relevant when further increasing the frequency of sampling. We found that increasing the number of field campaigns was more effective than increasing the number of measurements per day, provided a minimum of two measurements per day was used. Including night-time measurements significantly reduced the bias and was relevant in reducing the number of field campaigns when a lower level of acceptable error (RMSE < 5 %) was established. Using non-linear modelling instead of linear interpolation did improve the estimation of annual Rs, but not as expected. In conclusion, given that most of the studies of Rs use manual sampling techniques and apply only one measurement per day, we

  7. Experimental measurements of the thermal conductivity of ash deposits: Part 1. Measurement technique

    SciTech Connect

    A. L. Robinson; S. G. Buckley; N. Yang; L. L. Baxter

    2000-04-01

    This paper describes a technique developed to make in situ, time-resolved measurements of the effective thermal conductivity of ash deposits formed under conditions that closely replicate those found in the convective pass of a commercial boiler. Since ash deposit thermal conductivity is thought to be strongly dependent on deposit microstructure, the technique is designed to minimize the disturbance of the natural deposit microstructure. Traditional techniques for measuring deposit thermal conductivity generally do not preserve the sample microstructure. Experiments are described that demonstrate the technique, quantify experimental uncertainty, and determine the thermal conductivity of highly porous, unsintered deposits. The average measured conductivity of loose, unsintered deposits is 0.14 {+-} 0.03 W/(m K), approximately midway between rational theoretical limits for deposit thermal conductivity.

  8. Rapid jetting status inspection and accurate droplet volume measurement for a piezo drop-on-demand inkjet print head using a scanning mirror for display applications

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Youn; Kim, Minsung

    2017-02-01

    Despite the inherent fabrication simplicity of piezo drop-on-demand inkjet printing, the non-uniform deposition of colourants or electroluminescent organic materials leads to faulty display products, and hence, the importance of rapid jetting status inspection and accurate droplet volume measurement increases from a process perspective. In this work, various jetting status inspections and droplet volume measurement methods are reviewed by discussing their advantages and disadvantages, and then, the opportunities for the developed prototype with a scanning mirror are explored. This work demonstrates that jetting status inspection of 384 fictitious droplets can be performed within 17 s with maximum and minimum measurement accuracies of 0.2 ± 0.5 μ m for the fictitious droplets of 50 μ m in diameter and -1.2 ± 0.3 μ m for the fictitious droplets of 30 μ m in diameter, respectively. In addition to the new design of an inkjet monitoring instrument with a scanning mirror, two novel methods to accurately measure the droplet volume by amplifying a minute droplet volume difference and then converting to other physical properties are suggested and the droplet volume difference of ±0.3% is demonstrated to be discernible using numerical simulations, even with the low measurement accuracy of 1 μ m . When the fact is considered that the conventional vision-based method with a CCD camera requires the optical measurement accuracy less than 25 nm to measure the volume of an in-flight droplet in the nominal diameter of 50 μ m at the same volume measurement accuracy, the suggested method with the developed prototype offers a whole new opportunity to inkjet printing for display applications.

  9. Rapid jetting status inspection and accurate droplet volume measurement for a piezo drop-on-demand inkjet print head using a scanning mirror for display applications.

    PubMed

    Shin, Dong-Youn; Kim, Minsung

    2017-02-01

    Despite the inherent fabrication simplicity of piezo drop-on-demand inkjet printing, the non-uniform deposition of colourants or electroluminescent organic materials leads to faulty display products, and hence, the importance of rapid jetting status inspection and accurate droplet volume measurement increases from a process perspective. In this work, various jetting status inspections and droplet volume measurement methods are reviewed by discussing their advantages and disadvantages, and then, the opportunities for the developed prototype with a scanning mirror are explored. This work demonstrates that jetting status inspection of 384 fictitious droplets can be performed within 17 s with maximum and minimum measurement accuracies of 0.2 ± 0.5 μm for the fictitious droplets of 50 μm in diameter and -1.2 ± 0.3 μm for the fictitious droplets of 30 μm in diameter, respectively. In addition to the new design of an inkjet monitoring instrument with a scanning mirror, two novel methods to accurately measure the droplet volume by amplifying a minute droplet volume difference and then converting to other physical properties are suggested and the droplet volume difference of ±0.3% is demonstrated to be discernible using numerical simulations, even with the low measurement accuracy of 1 μm. When the fact is considered that the conventional vision-based method with a CCD camera requires the optical measurement accuracy less than 25 nm to measure the volume of an in-flight droplet in the nominal diameter of 50 μm at the same volume measurement accuracy, the suggested method with the developed prototype offers a whole new opportunity to inkjet printing for display applications.

  10. A 3D assessment tool for accurate volume measurement for monitoring the evolution of cutaneous leishmaniasis wounds.

    PubMed

    Zvietcovich, Fernando; Castañeda, Benjamin; Valencia, Braulio; Llanos-Cuentas, Alejandro

    2012-01-01

    Clinical assessment and outcome metrics are serious weaknesses identified on the systematic reviews of cutaneous Leishmaniasis wounds. Methods with high accuracy and low-variability are required to standarize study outcomes in clinical trials. This work presents a precise, complete and noncontact 3D assessment tool for monitoring the evolution of cutaneous Leishmaniasis (CL) wounds based on a 3D laser scanner and computer vision algorithms. A 3D mesh of the wound is obtained by a commercial 3D laser scanner. Then, a semi-automatic segmentation using active contours is performed to separate the ulcer from the healthy skin. Finally, metrics of volume, area, perimeter and depth are obtained from the mesh. Traditional manual 3D and 3D measurements are obtained as a gold standard. Experiments applied to phantoms and real CL wounds suggest that the proposed 3D assessment tool provides higher accuracy (error <2%) and precision rates (error <4%) than conventional manual methods (precision error < 35%). This 3D assessment tool provides high accuracy metrics which deserve more formal prospective study.

  11. Measurement of pelvic motion is a prerequisite for accurate estimation of hip joint work in maximum height squat jumping.

    PubMed

    Blache, Yoann; Bobbert, Maarten; Argaud, Sebastien; Pairot de Fontenay, Benoit; Monteil, Karine M

    2013-08-01

    In experiments investigating vertical squat jumping, the HAT segment is typically defined as a line drawn from the hip to some point proximally on the upper body (eg, the neck, the acromion), and the hip joint as the angle between this line and the upper legs (θUL-HAT). In reality, the hip joint is the angle between the pelvis and the upper legs (θUL-pelvis). This study aimed to estimate to what extent hip joint definition affects hip joint work in maximal squat jumping. Moreover, the initial pelvic tilt was manipulated to maximize the difference in hip joint work as a function of hip joint definition. Twenty-two male athletes performed maximum effort squat jumps in three different initial pelvic tilt conditions: backward (pelvisB), neutral (pelvisN), and forward (pelvisF). Hip joint work was calculated by integrating the hip net joint torque with respect to θUL-HAT (WUL-HAT) or with respect to θUL-pelvis (WUL-pelvis). θUL-HAT was greater than θUL-pelvis in all conditions. WUL-HAT overestimated WULpelvis by 33%, 39%, and 49% in conditions pelvisF, pelvisN, and pelvisB, respectively. It was concluded that θUL-pelvis should be measured when the mechanical output of hip extensor muscles is estimated.

  12. Ultrahigh mass resolution and accurate mass measurements as a tool to characterize oligomers in secondary organic aerosols.

    PubMed

    Reinhardt, Alain; Emmenegger, Christian; Gerrits, Bertran; Panse, Christian; Dommen, Josef; Baltensperger, Urs; Zenobi, Renato; Kalberer, Markus

    2007-06-01

    Organic aerosols are a major fraction, often more than 50%, of the total atmospheric aerosol mass. The chemical composition of the total organic aerosol mass is poorly understood, although hundreds of compounds have been identified in the literature. High molecular weight compounds have recently gained much attention because this class of compounds potentially represents a major fraction of the unexplained organic aerosol mass. Here we analyze secondary organic aerosols, generated in a smog chamber from alpha-pinene ozonolysis with ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). About 450 compounds are detected in the mass range of m/z 200-700. The mass spectrum is clearly divided into a low molecular weight range (monomer) and a high molecular weight range, where dimers and trimers are distinguishable. Using the Kendrick mass analysis, the elemental composition of about 60% of all peaks could be determined throughout the whole mass range. Most compounds have high O:C ratios between 0.4 and 0.6. Small compounds (i.e., monomers) have a higher maximum O:C ratio than dimers and trimers, suggesting that condensation reactions with, for example, the loss of water are important in the oligomer formation process. A program developed in-house was used to determine exact mass differences between peaks in the monomer, dimer, and trimer mass range to identify potential monomer building blocks, which form the co-oligomers observed in the mass spectrum. A majority of the peaks measured in the low mass region of the spectrum (m/z < 300) is also found in the calculated results. For the first time the elemental composition of the majority of peaks over a wide mass range was determined using advanced data analysis methods for the analysis of ultra-high-resolution MS data. Possible oligomer formation mechanisms in secondary organic aerosols were investigated.

  13. Characterising molecules for fundamental physics: an accurate spectroscopic model of methyltrioxorhenium derived from new infrared and millimetre-wave measurements.

    PubMed

    Asselin, Pierre; Berger, Yann; Huet, Thérèse R; Margulès, Laurent; Motiyenko, Roman; Hendricks, Richard J; Tarbutt, Michael R; Tokunaga, Sean K; Darquié, Benoît

    2017-02-08

    Precise spectroscopic analysis of polyatomic molecules enables many striking advances in physical chemistry and fundamental physics. We use several new high-resolution spectroscopic devices to improve our understanding of the rotational and rovibrational structure of methyltrioxorhenium (MTO), the achiral parent of a family of large oxorhenium compounds that are ideal candidate species for a planned measurement of parity violation in chiral molecules. Using millimetre-wave and infrared spectroscopy in a pulsed supersonic jet, a cryogenic buffer gas cell, and room temperature absorption cells, we probe the ground state and the Re[double bond, length as m-dash]O antisymmetric and symmetric stretching excited states of both CH3(187)ReO3 and CH3(185)ReO3 isotopologues in the gas phase with unprecedented precision. By extending the rotational spectra to the 150-300 GHz range, we characterize the ground state rotational and hyperfine structure up to J = 43 and K = 41, resulting in refinements to the rotational, quartic and hyperfine parameters, and the determination of sextic parameters and a centrifugal distortion correction to the quadrupolar hyperfine constant. We obtain rovibrational data for temperatures between 6 and 300 K in the 970-1015 cm(-1) range, at resolutions down to 8 MHz and accuracies of 30 MHz. We use these data to determine more precise excited-state rotational, Coriolis and quartic parameters, as well as the ground-state centrifugal distortion parameter DK of the (187)Re isotopologue. We also account for hyperfine structure in the rovibrational transitions and hence determine the upper state rhenium atom quadrupole coupling constant eQq'.

  14. Experimental investigation on mass flow rate measurements using fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Thekkethil, S. R.; Thomas, R. J.; Neumann, H.; Ramalingam, R.

    2017-02-01

    Flow measurement and control of cryogens is one of the major requirements of systems such as superconductor magnets for fusion reactors, MRI magnets etc. They can act as an early diagnostic tool for detection of any faults and ensure correct distribution of cooling load while also accessing thermal performance of the devices. Fibre Bragg Grating (FBG) sensors provide compact and accurate measurement systems which have added advantages such as immunity towards electrical and magnetic interference, low attenuation losses and remote sensing. This paper summarizes the initial experimental investigations and calibration of a novel FBG based mass flow meter. This design utilizes the viscous drag due to the flow to induce a bending strain on the fibre. The strain experienced by the fibre will be proportional to the flowrate and can be measured in terms of Bragg wavelength shift. The flowmeter is initially tested at atmospheric conditions using helium. The results are summarized and the performance parameters of the sensor are estimated. The results were also compared to a numerical model and further results for liquid helium is also reported. An overall sensitivity of 29 pm.(g.s-1)-1 was obtained for a helium flow, with a resolution of 0.2 g.s-1. A hysteresis error of 8 pm was also observed during load-unload cycles. The sensor is suitable for further tests using cryogens.

  15. Experimental Measurements and Density Functional Theory Calculations of Continuum Lowering in Strongly Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Vinko, Sam

    2014-10-01

    An accurate description of the ionization potential depression (IPD) of ions in plasmas due to their interaction with the environment is a fundamental problem in plasma physics, playing a key role in determining the ionization balance, charge state distribution, opacity and plasma equation of state. Here I present the first experimental investigation of the IPD as a function of ionic charge state in a range of dense Mg, Al and Si plasmas, using the Linac Coherent Light Source X-ray free-electron laser. The measurements show significantly larger IPDs than are predicted by the most commonly used models, such as that of Stewart-Pyatt, or the ion-sphere model of Zimmerman-More. Instead, plasma simulations using finite-temperature density functional theory with excited-state projector augmented-wave potentials show excellent agreement with the experimental results and explain the stronger-than-expected continuum lowering through the electronic structure of the valence states in these strong-coupling conditions, which retain much of their atomic characteristics close to the ion core regions. These results have a profound impact on the understanding and modelling of plasmas over a wide range of warm- and hot-dense matter conditions.

  16. Accurate measurements of 13C-13C distances in uniformly 13C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Khaneja, Navin; Nielsen, Niels Chr.

    2014-09-01

    Application of sets of 13C-13C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important 13C-13C distances in uniformly 13C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl (13C') and aliphatic (13Caliphatic) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly 13C,15N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of 13C'-13Caliphatic distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform 13C,15N-labeling on the FGAIL fragment.

  17. Accurate measurement of heteronuclear dipolar couplings by phase-alternating R-symmetry (PARS) sequences in magic angle spinning NMR spectroscopy

    SciTech Connect

    Hou, Guangjin E-mail: tpolenov@udel.edu; Lu, Xingyu E-mail: lexvega@comcast.net; Vega, Alexander J. E-mail: lexvega@comcast.net; Polenova, Tatyana E-mail: tpolenov@udel.edu

    2014-09-14

    We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear {sup 1}H-X (X = {sup 13}C, {sup 15}N, {sup 31}P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the {sup 1}H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the {sup 1}H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from {sup 1}H chemical shift anisotropy, while keeping the {sup 1}H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [{sup 15}N]-N-acetyl-valine and [U-{sup 13}C,{sup 15}N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate {sup 1}H-{sup 15}N dipolar couplings in the context of 3D experiments is presented on U-{sup 13}C,{sup 15}N-enriched dynein light chain protein LC8.

  18. Accurate measurement of heteronuclear dipolar couplings by phase-alternating R-symmetry (PARS) sequences in magic angle spinning NMR spectroscopy.

    PubMed

    Hou, Guangjin; Lu, Xingyu; Vega, Alexander J; Polenova, Tatyana

    2014-09-14

    We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear (1)H-X (X = (13)C, (15)N, (31)P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the (1)H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the (1)H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from (1)H chemical shift anisotropy, while keeping the (1)H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [(15)N]-N-acetyl-valine and [U-(13)C,(15)N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate (1)H-(15)N dipolar couplings in the context of 3D experiments is presented on U-(13)C,(15)N-enriched dynein light chain protein LC8.

  19. Experimental measurement of tympanic membrane response for finite element model validation of a human middle ear.

    PubMed

    Ahn, Tae-Soo; Baek, Moo-Jin; Lee, Dooho

    2013-01-01

    The middle ear consists of a tympanic membrane, ligaments, tendons, and three ossicles. An important function of the tympanic membrane is to deliver exterior sound stimulus to the ossicles and inner ear. In this study, the responses of the tympanic membrane in a human ear were measured and compared with those of a finite element model of the middle ear. A laser Doppler vibrometer (LDV) was used to measure the dynamic responses of the tympanic membrane, which had the measurement point on the cone of light of the tympanic membrane. The measured subjects were five Korean male adults and a cadaver. The tympanic membranes were stimulated using pure-tone sine waves at 18 center frequencies of one-third octave band over a frequency range of 200 Hz ~10 kHz with 60 and 80 dB sound pressure levels. The measured responses were converted into the umbo displacement transfer function (UDTF) with a linearity assumption. The measured UDTFs were compared with the calculated UDTFs using a finite element model for the Korean human middle ear. The finite element model of the middle ear consists of three ossicles, a tympanic membrane, ligaments, and tendons. In the finite element model, the umbo displacements were calculated under a unit sound pressure on the tympanic membrane. The UDTF of the finite element model exhibited good agreement with that of the experimental one in low frequency range, whereas in higher frequency band, the two response functions deviated from each other, which demonstrates that the finite element model should be updated with more accurate material properties and/or a frequency dependent material model.

  20. Experimental Modal Analysis and Dynamic Component Synthesis. Volume 2. Measurement Techniques for Experimental Modal Analysis

    DTIC Science & Technology

    1987-12-01

    spring component must be linear and the force due to the resistance of the dashpot must be proportional to the velocity; thus, the equation of motion is...linear. However, in many cases, the dashpot resistance is more accurately described by a term which is proportional to the square of the velocity...Furthermore, the resistance is always opposing the motion. This nonlinear equation of motion is written as: m~i +c C. i i+ kx 0 (79) This is an example

  1. Evidence that bisphenol A (BPA) can be accurately measured without contamination in human serum and urine, and that BPA causes numerous hazards from multiple routes of exposure.

    PubMed

    vom Saal, Frederick S; Welshons, Wade V

    2014-12-01

    There is extensive evidence that bisphenol A (BPA) is related to a wide range of adverse health effects based on both human and experimental animal studies. However, a number of regulatory agencies have ignored all hazard findings. Reports of high levels of unconjugated (bioactive) serum BPA in dozens of human biomonitoring studies have also been rejected based on the prediction that the findings are due to assay contamination and that virtually all ingested BPA is rapidly converted to inactive metabolites. NIH and industry-sponsored round robin studies have demonstrated that serum BPA can be accurately assayed without contamination, while the FDA lab has acknowledged uncontrolled assay contamination. In reviewing the published BPA biomonitoring data, we find that assay contamination is, in fact, well controlled in most labs, and cannot be used as the basis for discounting evidence that significant and virtually continuous exposure to BPA must be occurring from multiple sources.

  2. Evidence that bisphenol A (BPA) can be accurately measured without contamination in human serum and urine, and that BPA causes numerous hazards from multiple routes of exposure

    PubMed Central

    vom Saal, Frederick S.; Welshons, Wade V.

    2016-01-01

    There is extensive evidence that bisphenol A (BPA) is related to a wide range of adverse health effects based on both human and experimental animal studies. However, a number of regulatory agencies have ignored all hazard findings. Reports of high levels of unconjugated (bioactive) serum BPA in dozens of human biomonitoring studies have also been rejected based on the prediction that the findings are due to assay contamination and that virtually all ingested BPA is rapidly converted to inactive metabolites. NIH and industry-sponsored round robin studies have demonstrated that serum BPA can be accurately assayed without contamination, while the FDA lab has acknowledged uncontrolled assay contamination. In reviewing the published BPA biomonitoring data, we find that assay contamination is, in fact, well controlled in most labs, and cannot be used as the basis for discounting evidence that significant and virtually continuous exposure to BPA must be occurring from multiple sources. PMID:25304273

  3. The Hall effect in the organic conductor TTF-TCNQ: choice of geometry for accurate measurements of a highly anisotropic system.

    PubMed

    Tafra, E; Culo, M; Basletić, M; Korin-Hamzić, B; Hamzić, A; Jacobsen, C S

    2012-02-01

    We have measured the Hall effect on recently synthesized single crystals of the quasi-one-dimensional organic conductor TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane), a well known charge transfer complex that has two kinds of conductive stacks: the donor (TTF) and the acceptor (TCNQ) chains. The measurements were performed in the temperature interval 30 K < T < 300 K and for several different magnetic field and current directions through the crystal. By applying the equivalent isotropic sample approach, we have demonstrated the importance of the choice of optimal geometry for accurate Hall effect measurements. Our results show, contrary to past belief, that the Hall coefficient does not depend on the geometry of measurements and that the Hall coefficient value is approximately zero in the high temperature region (T > 150 K), implying that there is no dominance of either the TTF or the TCNQ chain. At lower temperatures our measurements clearly prove that all three phase transitions of TTF-TCNQ could be identified from Hall effect measurements.

  4. Investigation and experimental measurement of scissor blade cutting forces using fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Callaghan, D. J.; Rajan, G.; McGrath, M. M.; Coyle, E.; Semenova, Y.; Farrell, G.

    2011-10-01

    This paper reports on unique and scalable sensorized medical scissor blades for application in minimally invasive robotic surgery. The blades exploit the strain sensing capabilities of a single fiber Bragg grating (FBG) sensor bonded to the blade surface. This smart sensing structure allows detection of friction and material fracture forces during cutting and subsequently enables accurate estimation of the blade kinetic friction coefficient and fracture toughness values of the material being cut. We present theory on the determination of strain variation along the blade length during combined direct and lateral loading of the blade element during operation. Demonstration of the sensorized instrument is realized on an application specific experimental test-bed employing a commercial interrogation system for signal demodulation. Friction and cutting forces measured using the FBG are validated against load cell force data from the test-bed. Characterization tests showed that the sensorized blade has an unfiltered force sensing resolution of 0.5 N over a 30 N load range. This work demonstrates that a single optical fiber placed onto cutting instrument blades can, in an unobtrusive manner, reliably measure friction forces and material fracture properties during surgical cutting.

  5. The Heat Output of the Waimangu, Waiotapu-Waikite and Reporoa Geothermal Systems (NZ): Do Chloride Fluxes Provide an Accurate Measure?

    SciTech Connect

    Bibby, H.M.; Glover, R.B.; Whiteford, P.C.

    1995-01-01

    Geothermal waters from the Waimangu, Waiotapu-Waikite and Reporoa geothermal systems find their way into three separate watersheds. The heat flow data from each of these drainage areas have been assessed making it possible to compare the heat outputs from two independent methods: direct heat measurements and the chloride flux method. For both the Waiotapu/Reporoa Valley drainage and the Waikite drainage a discrepancy exists between the two assessments, with the heat output observed at the surface (Waiotapu-540 {+-} 110 MW; Waikite-80 MW) nearly double of that calculated from the chloride flux (300 MW; 36 MW respectively). It appears that much of the throughput of chloride does not reach the surface within the area which was monitored and the basic assumption on which the method is based has been violated. For Waimangu the direct heat output is assessed as 510 {+-} 60 MW. However the ratio of enthalpy to chloride concentration of the source fluid is not well determined. Depending on the ratio chosen the heat output could lie between 360 and 800 MW. Although the chloride flux is accurately known, the heat output cannot be measured accurately without well determined data on the source fluid at depth.

  6. Direct Measurements of Quantum Kinetic Energy Tensor in Stable and Metastable Water near the Triple Point: An Experimental Benchmark.

    PubMed

    Andreani, Carla; Romanelli, Giovanni; Senesi, Roberto

    2016-06-16

    This study presents the first direct and quantitative measurement of the nuclear momentum distribution anisotropy and the quantum kinetic energy tensor in stable and metastable (supercooled) water near its triple point, using deep inelastic neutron scattering (DINS). From the experimental spectra, accurate line shapes of the hydrogen momentum distributions are derived using an anisotropic Gaussian and a model-independent framework. The experimental results, benchmarked with those obtained for the solid phase, provide the state of the art directional values of the hydrogen mean kinetic energy in metastable water. The determinations of the direction kinetic energies in the supercooled phase, provide accurate and quantitative measurements of these dynamical observables in metastable and stable phases, that is, key insight in the physical mechanisms of the hydrogen quantum state in both disordered and polycrystalline systems. The remarkable findings of this study establish novel insight into further expand the capacity and accuracy of DINS investigations of the nuclear quantum effects in water and represent reference experimental values for theoretical investigations.

  7. Experimental Measurements And Evaluation Of Indoor Microclimate Conditions

    NASA Astrophysics Data System (ADS)

    Kraliková, Ružena; Sokolová, Hana

    2015-07-01

    The paper deals with monitoring of workplace where technological equipment produces heat during hot summer days. The thermo-hygric microclimate measurement took place during daily work shift, and was carried out at 5 choosen measuring points. Since there was radiation heat presented in workplace and workers worked at different places, the thermal environment was classified as a heterogeneous and unstationary area. The measurement, result processing and interpretation was carried out according to the valid legislation of Slovak Republic.

  8. Quantum Dynamics Simulations for Modeling Experimental Pump-Probe Measurements

    NASA Astrophysics Data System (ADS)

    Pearson, Brett; Nayyar, Sahil; Liss, Kyle; Weinacht, Thomas

    2016-05-01

    Time-resolved studies of quantum dynamics have benefited greatly from developments in ultrafast table-top and free electron lasers. Advances in computer software and hardware have lowered the barrier for performing calculations such that relatively simple simulations allow for direct comparison with experimental results. We describe here a set of quantum dynamics calculations in low-dimensional molecular systems. The calculations incorporate coupled electronic-nuclear dynamics, including two interactions with an applied field and nuclear wave packet propagation. The simulations were written and carried out by undergraduates as part of a senior research project, with the specific goal of allowing for detailed interpretation of experimental pump-probe data (in additional to the pedagogical value).

  9. Experimental techniques for cross-section measurements. [for electron impacts

    NASA Technical Reports Server (NTRS)

    Trajmar, S.; Register, D. F.

    1984-01-01

    Attention is given to electron collision phenomena which can be studied under single-collision conditions at low and intermediate electron impact energies, ranging from threshold to a few hundred eV, using gas phase molecular targets. Several of the experimental methods discussed were first developed and applied to atoms, but are equally applicable to molecules with minor modifications in the interpretation of the data, due to the greater complexity of molecular systems.

  10. Problems in Measuring Racial Attitudes: An Experimental Approach.

    ERIC Educational Resources Information Center

    Sedlacek, William E.; And Others

    Problems in measuring the attitudes of whites toward blacks have included: (1) Lack of contemporary content in existing measures; (2) Difficulty of determining scale validity; and, (3) The strong social reinforcement for being "tolerant" toward blacks making the assessment of "true" racial attitudes more difficult. The…

  11. Operational measure of entanglement based on experimental consequences.

    SciTech Connect

    Grondalski, J. P.; James, D. F.

    2002-01-01

    The maximum eigenvalue of the real part of the density matrix expressed in a maximally entangled basis with a particular phase relationship can be used as an operational measure of entanglement. This measure is related to the fidelity, maximized with a local unitary operating on either subsystem, of a standard dense coding, teleportation, or entanglement swapping protocol.

  12. Race as an Experimenter Effect In Racial Attitude Measurement.

    ERIC Educational Resources Information Center

    Sedlacek, William E.; Brooks, Glenwood C., Jr.

    Sedlacek and Brooks in measuring the attitudes of whites toward blacks with the Situational Attitude Scale (SAS) have used trained white administrators in all previous studies. The purpose of white administrators was to avoid calling attention to the racial variable being measured. However the instrument is not the entire simulus presented to…

  13. Experimental clean combustor program noise measurement addendum, phase 1

    NASA Technical Reports Server (NTRS)

    Emmerling, J. J.

    1975-01-01

    The test results of combustor noise measurements taken with waveguide probes are presented. Waveguide probes were shown to be a viable measurement technique for determining high sound pressure level broadband noise. A total of six full-scale annular combustors were tested and included the three advanced combustor designs: swirl-can, radial/axial, and double annular.

  14. Experimental Methodology for Determining Turbomachinery Blade Damping Using Magnetic Bearing Excitation and Non-Contacting Optical Measurements

    NASA Technical Reports Server (NTRS)

    Provenza, Andrew J.; Duffy, Kirsten P.

    2010-01-01

    Experiments to determine the effects of turbomachinery fan blade damping concepts such as passively shunted piezoelectric materials on blade response are ongoing at the NASA Glenn Research Center. A vertical rotor is suspended and excited with active magnetic bearings (AMBs) usually in a vacuum chamber to eliminate aerodynamic forces. Electromagnetic rotor excitation is superimposed onto rotor PD-controlled support and can be fixed to either a stationary or rotating frame of reference. The rotor speed is controlled with an air turbine system. Blade vibrations are measured using optical probes as part of a Non-Contacting Stress Measurement System (NSMS). Damping is calculated from these measurements. It can be difficult to get accurate damping measurements using this experimental setup and some of the details of how to obtain quality results are seemingly nontrivial. The intent of this paper is to present those details.

  15. Accurate quantitative measurements of brachial artery cross-sectional vascular area and vascular volume elastic modulus using automated oscillometric measurements: comparison with brachial artery ultrasound

    PubMed Central

    Tomiyama, Yuuki; Yoshinaga, Keiichiro; Fujii, Satoshi; Ochi, Noriki; Inoue, Mamiko; Nishida, Mutumi; Aziki, Kumi; Horie, Tatsunori; Katoh, Chietsugu; Tamaki, Nagara

    2015-01-01

    Increasing vascular diameter and attenuated vascular elasticity may be reliable markers for atherosclerotic risk assessment. However, previous measurements have been complex, operator-dependent or invasive. Recently, we developed a new automated oscillometric method to measure a brachial artery's estimated area (eA) and volume elastic modulus (VE). The aim of this study was to investigate the reliability of new automated oscillometric measurement of eA and VE. Rest eA and VE were measured using the recently developed automated detector with the oscillometric method. eA was estimated using pressure/volume curves and VE was defined as follows (VE=Δ pressure/ (100 × Δ area/area) mm Hg/%). Sixteen volunteers (age 35.2±13.1 years) underwent the oscillometric measurements and brachial ultrasound at rest and under nitroglycerin (NTG) administration. Oscillometric measurement was performed twice on different days. The rest eA correlated with ultrasound-measured brachial artery area (r=0.77, P<0.001). Rest eA and VE measurement showed good reproducibility (eA: intraclass correlation coefficient (ICC)=0.88, VE: ICC=0.78). Under NTG stress, eA was significantly increased (12.3±3.0 vs. 17.1±4.6 mm2, P<0.001), and this was similar to the case with ultrasound evaluation (4.46±0.72 vs. 4.73±0.75 mm, P<0.001). VE was also decreased (0.81±0.16 vs. 0.65±0.11 mm Hg/%, P<0.001) after NTG. Cross-sectional vascular area calculated using this automated oscillometric measurement correlated with ultrasound measurement and showed good reproducibility. Therefore, this is a reliable approach and this modality may have practical application to automatically assess muscular artery diameter and elasticity in clinical or epidemiological settings. PMID:25693851

  16. Knowing what the brain is seeing in three dimensions: A novel, noninvasive, sensitive, accurate, and low-noise technique for measuring ocular torsion.

    PubMed

    Otero-Millan, Jorge; Roberts, Dale C; Lasker, Adrian; Zee, David S; Kheradmand, Amir

    2015-01-01

    Torsional eye movements are rotations of the eye around the line of sight. Measuring torsion is essential to understanding how the brain controls eye position and how it creates a veridical perception of object orientation in three dimensions. Torsion is also important for diagnosis of many vestibular, neurological, and ophthalmological disorders. Currently, there are multiple devices and methods that produce reliable measurements of horizontal and vertical eye movements. Measuring torsion, however, noninvasively and reliably has been a longstanding challenge, with previous methods lacking real-time capabilities or suffering from intrusive artifacts. We propose a novel method for measuring eye movements in three dimensions using modern computer vision software (OpenCV) and concepts of iris recognition. To measure torsion, we use template matching of the entire iris and automatically account for occlusion of the iris and pupil by the eyelids. The current setup operates binocularly at 100 Hz with noise <0.1° and is accurate within 20° of gaze to the left, to the right, and up and 10° of gaze down. This new method can be widely applicable and fill a gap in many scientific and clinical disciplines.

  17. Knowing what the brain is seeing in three dimensions: A novel, noninvasive, sensitive, accurate, and low-noise technique for measuring ocular torsion

    PubMed Central

    Otero-Millan, Jorge; Roberts, Dale C.; Lasker, Adrian; Zee, David S.; Kheradmand, Amir

    2015-01-01

    Torsional eye movements are rotations of the eye around the line of sight. Measuring torsion is essential to understanding how the brain controls eye position and how it creates a veridical perception of object orientation in three dimensions. Torsion is also important for diagnosis of many vestibular, neurological, and ophthalmological disorders. Currently, there are multiple devices and methods that produce reliable measurements of horizontal and vertical eye movements. Measuring torsion, however, noninvasively and reliably has been a longstanding challenge, with previous methods lacking real-time capabilities or suffering from intrusive artifacts. We propose a novel method for measuring eye movements in three dimensions using modern computer vision software (OpenCV) and concepts of iris recognition. To measure torsion, we use template matching of the entire iris and automatically account for occlusion of the iris and pupil by the eyelids. The current setup operates binocularly at 100 Hz with noise <0.1° and is accurate within 20° of gaze to the left, to the right, and up and 10° of gaze down. This new method can be widely applicable and fill a gap in many scientific and clinical disciplines. PMID:26587699

  18. Measurement of neutron spectra in the experimental reactor LR-0

    SciTech Connect

    Prenosil, Vaclav; Mravec, Filip; Veskrna, Martin; Kostal, Michal; Matej, Zdenek; Cvachovec, Frantisek

    2015-07-01

    The measurement of fast neutron fluxes is important in many areas of nuclear technology. It affects the stability of the reactor structural components, performance of fuel, and also the fuel manner. The experiments performed at the LR-0 reactor were in the past focused on the measurement of neutron field far from the core, in reactor pressure vessel simulator or in biological shielding simulator. In the present the measurement in closer regions to core became more important, especially measurements in structural components like reactor baffle. This importance increases with both reactor power increase and also long term operation. Other important task is an increasing need for the measurement close to the fuel. The spectra near the fuel are aimed due to the planned measurements with the FLIBE salt, in FHR / MSR research, where one of the task is the measurement of the neutron spectra in it. In both types of experiments there is strong demand for high working count rate. The high count rate is caused mainly by high gamma background and by high fluxes. The fluxes in core or in its vicinity are relatively high to ensure safe reactor operation. This request is met in the digital spectroscopic apparatus. All experiments were realized in the LR-0 reactor. It is an extremely flexible light water zero-power research reactor, operated by the Research Center Rez (Czech Republic). (authors)

  19. Calibration of aero-structural reduced order models using full-field experimental measurements

    NASA Astrophysics Data System (ADS)

    Perez, R.; Bartram, G.; Beberniss, T.; Wiebe, R.; Spottswood, S. M.

    2017-03-01

    The structural response of hypersonic aircraft panels is a multi-disciplinary problem, where the nonlinear structural dynamics, aerodynamics, and heat transfer models are coupled. A clear understanding of the impact of high-speed flow effects on the structural response, and the potential influence of the structure on the local environment, is needed in order to prevent the design of overly-conservative structures, a common problem in past hypersonic programs. The current work investigates these challenges from a structures perspective. To this end, the first part of this investigation looks at the modeling of the response of a rectangular panel to an external heating source (thermo-structural coupling) where the temperature effect on the structure is obtained from forward looking infrared (FLIR) measurements and the displacement via 3D-digital image correlation (DIC). The second part of the study uses data from a previous series of wind-tunnel experiments, performed to investigate the response of a compliant panel to the effects of high-speed flow, to train a pressure surrogate model. In this case, the panel aero-loading is obtained from fast-response pressure sensitive paint (PSP) measurements, both directly and from the pressure surrogate model. The result of this investigation is the use of full-field experimental measurements to update the structural model and train a computational efficient model of the loading environment. The use of reduced order models, informed by these full-field physical measurements, is a significant step toward the development of accurate simulation models of complex structures that are computationally tractable.

  20. Accurate measurements and temperature dependence of the water vapor self-continuum absorption in the 2.1 μm atmospheric window.

    PubMed

    Ventrillard, I; Romanini, D; Mondelain, D; Campargue, A

    2015-10-07

    In spite of its importance for the evaluation of the Earth radiative budget, thus for climate change, very few measurements of the water vapor continuum are available in the near infrared atmospheric windows especially at temperature conditions relevant for our atmosphere. In addition, as a result of the difficulty to measure weak broadband absorption signals, the few available measurements show large disagreements. We report here accurate measurements of the water vapor self-continuum absorption in the 2.1 μm window by Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS) for two spectral points located at the low energy edge and at the center of the 2.1 μm transparency window, at 4302 and 4723 cm(-1), respectively. Self-continuum cross sections, CS, were retrieved with a few % relative uncertainty, from the quadratic dependence of the spectrum base line level measured as a function of water vapor pressure, between 0 and 16 Torr. At 296 K, the CS value at 4302 cm(-1) is found 40% higher than predicted by the MT_CKD V2.5 model, while at 4723 cm(-1), our value is 5 times larger than the MT_CKD value. On the other hand, these OF-CEAS CS values are significantly smaller than recent measurements by Fourier transform spectroscopy at room temperature. The temperature dependence of the self-continuum cross sections was also investigated for temperatures between 296 K and 323 K (23-50 °C). The derived temperature variation is found to be similar to that derived from previous Fourier transform spectrometer (FTS) measurements performed at higher temperatures, between 350 K and 472 K. The whole set of measurements spanning the 296-472 K temperature range follows a simple exponential law in 1/T with a slope close to the dissociation energy of the water dimer, D0 ≈ 1100 cm(-1).

  1. Dynamic Measurement of the J Integral in Ductile Metals: Comparison of Experimental and Numerical Techniques

    DTIC Science & Technology

    1988-08-01

    proven experimental techniques for measruing J under static loading, few proven experimental techniques exist for measurement of the time history of J...Freund[9], who estimate jd by measuring the tran- sient load displacement records and by using the quasi-static formula for deeply notched round bars...HY-100 steel, loaded by a projectile, are compared to experimental measurements performed by means of the interferometric strain- displacement gauge

  2. Application of the energy reassignment method to measure accurate Rayleigh and Love wave group velocities from ambient seismic noise cross-correlations

    NASA Astrophysics Data System (ADS)

    Witek, M.; Kang, T. S.; van der Lee, S.

    2015-12-01

    We have collected three-component data from 122 Korean accelerometer stations for the month of December in 2014. We apply similar techniques described by Zha et al. (2013) to retrieve accurate station orientation angles, in order to rotate the horizontal component data into the radial and transverse frame of reference, and for subsequent measurement of Love wave group velocity dispersion. We simultaneously normalize all three components of a daily noise record via the frequency-time normalization (FTN) method. Each component is divided by the average signal envelope in an effort to retain relative amplitude information between all three components. Station orientations are found by a grid search for the orientation azimuth which maximizes the coherency between the radial-vertical cross-correlation and the Hilbert transformed vertical-vertical cross-correlation. After measuring orientation angles, we cross-correlate and rotate the data. Typically, the group velocity dispersion curves are measured using the frequency time analysis technique (FTAN), effectively producing spectrograms with significant uncertainty in the time-frequency plane. The spectrogram approach retains only the amplitude information of the short-time Fourier transform (STFT). However, Kodera et al (1976) show that by taking into account the phase information, the concepts of instantaneous frequency and group-time delay can be used to compute the first moment of the signal power in the frequency and time domains. During energy reassignment, the signal power calculated using the STFT at a point (t0,f0t_0, f_0) is reassigned to the location of the first moment (t^g,f^ihat{t}_g,hat{f}_i), where t^ghat{t}_g is the group-time delay and f^ihat{f}_i is the instantaneous frequency. We apply the method of energy reassignment to produce precise Rayleigh and Love wave group velocity measurements in the frequency range 0.1 - 1.0 Hz. Tests on synthetic data show more accurate retrieval of group velocities at

  3. Science Experimenter: How to Measure the Solar Constant.

    ERIC Educational Resources Information Center

    Mims, Forrest M., III

    1991-01-01

    Presented is a way to measure the sun's radiation by using a radiometer. Directions for building both simple and complex radiometers, circuit diagrams, and an explanation on how they work are included. (KR)

  4. Rapid and accurate measurement of left ventricular function with a new second-harmonic fast-rotating transducer and semi-automated border detection.

    PubMed

    Krenning, Boudewijn J; Voormolen, Marco M; van Geuns, Robert-Jan; Vletter, W B; Lancée, Charles T; de Jong, Nico; Ten Cate, Folkert J; van der Steen, Anton F W; Roelandt, Jos R T C

    2006-07-01

    Measurement of left ventricular (LV) volume and function are the most common clinical referral questions to the echocardiography laboratory. A fast, practical, and accurate method would offer important advantages to obtain this important information. To validate a new practical method for rapid measurement of LV volume and function. We developed a continuous fast-rotating transducer, with second-harmonic capabilities, for three-dimensional echocardiography (3DE). Fifteen cardiac patients underwent both 3DE and magnetic resonance imaging (reference method) on the same day. 3DE image acquisition was performed during a 10-second breath-hold with a frame rate of 100 frames/sec and a rotational speed of 6 rotations/sec. The individual images were postprocessed with Matlab software using multibeat data fusion. Subsequently, with these images, 12 datasets per cardiac cycle were reconstructed, each comprising seven equidistant cross-sectional images for analysis in the new TomTec 4DLV analysis software, which uses a semi-automated border detection (ABD) algorithm. The ABD requires an average analysis time of 15 minutes per patient. A strong correlation was found between LV end-diastolic volume (r = 0.99; y = 0.95x - 1.14 ml; SEE = 6.5 ml), LV end-systolic volume (r = 0.96; y = 0.89x + 7.91 ml; SEE = 7.0 ml), and LV ejection fraction (r = 0.93; y = 0.69x + 13.36; SEE = 2.4%). Inter- and intraobserver agreement for all measurements was good. The fast-rotating transducer with new ABD software is a dedicated tool for rapid and accurate analysis of LV volume and function.

  5. Rapid, accurate, and non-invasive measurement of zebrafish axial length and other eye dimensions using SD-OCT allows longitudinal analysis of myopia and emmetropization.

    PubMed

    Collery, Ross F; Veth, Kerry N; Dubis, Adam M; Carroll, Joseph; Link, Brian A

    2014-01-01

    Refractive errors in vision can be caused by aberrant axial length of the eye, irregular corneal shape, or lens abnormalities. Causes of eye length overgrowth include multiple genetic loci, and visual parameters. We evaluate zebrafish as a potential animal model for studies of the genetic, cellular, and signaling basis of emmetropization and myopia. Axial length and other eye dimensions of zebrafish were measured using spectral domain-optical coherence tomography (SD-OCT). We used ocular lens and body metrics to normalize and compare eye size and relative refractive error (difference between observed retinal radial length and controls) in wild-type and lrp2 zebrafish. Zebrafish were dark-reared to assess effects of visual deprivation on eye size. Two relative measurements, ocular axial length to body length and axial length to lens diameter, were found to accurately normalize comparisons of eye sizes between different sized fish (R2=0.9548, R2=0.9921). Ray-traced focal lengths of wild-type zebrafish lenses were equal to their retinal radii, while lrp2 eyes had longer retinal radii than focal lengths. Both genetic mutation (lrp2) and environmental manipulation (dark-rearing) caused elongated eye axes. lrp2 mutants had relative refractive errors of -0.327 compared to wild-types, and dark-reared wild-type fish had relative refractive errors of -0.132 compared to light-reared siblings. Therefore, zebrafish eye anatomy (axial length, lens radius, retinal radius) can be rapidly and accurately measured by SD-OCT, facilitating longitudinal studies of regulated eye growth and emmetropization. Specifically, genes homologous to human myopia candidates may be modified, inactivated or overexpressed in zebrafish, and myopia-sensitizing conditions used to probe gene-environment interactions. Our studies provide foundation for such investigations into genetic contributions that control eye size and impact refractive errors.

  6. Survey and Experimental Testing of Nongravimetric Mass Measurement Devices

    NASA Technical Reports Server (NTRS)

    Oakey, W. E.; Lorenz, R.

    1977-01-01

    Documentation presented describes the design, testing, and evaluation of an accelerated gravimetric balance, a low mass air bearing oscillator of the spring-mass type, and a centrifugal device for liquid mass measurement. A direct mass readout method was developed to replace the oscillation period readout method which required manual calculations to determine mass. A protoype 25 gram capacity micro mass measurement device was developed and tested.

  7. Experimental apparatus for measurements of electron impact excitation

    NASA Technical Reports Server (NTRS)

    Lafyatis, G. P.; Kohl, J. L.; Gardner, L. D.

    1987-01-01

    An ion beam apparatus for the absolute measurement of collision cross sections in singly and multiply charged ions is described. An inclined electron and ion beams arrangement is used. Emitted photons from the decay of collision produced excited states are collected by a mirror and imaged onto a photomultiplier. Absolute measurements of the electron impact excitation of the 2s-2p transition in C(3+) were used to demonstrate the reliability of the apparatus.

  8. Experimental proposal for measuring the Gouy phase of matter waves

    NASA Astrophysics Data System (ADS)

    da Paz, I. G.; Saldanha, P. L.; Nemes, M. C.; Peixoto de Faria, J. G.

    2011-12-01

    The Schrödinger equation for an atomic beam predicts that it must have a phase anomaly near the beam waist analogous to the Gouy phase of an electromagnetic beam. We propose here a feasible experiment that allows for direct determination of this anomalous phase using Ramsey interferometry with Rydberg atoms. Possible experimental limitations are discussed, and shown to be completely under control within present-day technology. We also discuss how this finding can open the possibility of using the spatial mode wavefunctions of atoms as q-dits, since the Gouy phase is an essential ingredient for making rotations in the quantum states.

  9. Experimental study of coaxial nozzle exhaust noise. [acoustic measurements

    NASA Technical Reports Server (NTRS)

    Goodykoontz, J. H.; Stone, J. R.

    1979-01-01

    Experimental results are presented for static acoustic model tests of various geometrical configurations of coaxial nozzles operating over a range of flow conditions. The geometrical configurations consisted of nozzles with coplanar and non-coplanar exit planes and various exhaust area ratios. Primary and secondary nozzle flows were varied independently over a range of nozzle pressure ratios from 1.4 to 3.0 and gas temperatures from 280 to 1100 K. Acoustic data are presented for the conventional mode of coaxial nozzle operation as well as for the inverted velocity profile mode. Comparisons are presented to show the effect of configuration and flow changes on the acoustic characteristics of the nozzles.

  10. Phase-coded microwave signal generation based on a single electro-optical modulator and its application in accurate distance measurement.

    PubMed

    Zhang, Fangzheng; Ge, Xiaozhong; Gao, Bindong; Pan, Shilong

    2015-08-24

    A novel scheme for photonic generation of a phase-coded microwave signal is proposed and its application in one-dimension distance measurement is demonstrated. The proposed signal generator has a simple and compact structure based on a single dual-polarization modulator. Besides, the generated phase-coded signal is stable and free from the DC and low-frequency backgrounds. An experiment is carried out. A 2 Gb/s phase-coded signal at 20 GHz is successfully generated, and the recovered phase information agrees well with the input 13-bit Barker code. To further investigate the performance of the proposed signal generator, its application in one-dimension distance measurement is demonstrated. The measurement accuracy is less than 1.7 centimeters within a measurement range of ~2 meters. The experimental results can verify the feasibility of the proposed phase-coded microwave signal generator and also provide strong evidence to support its practical applications.

  11. Breath-hold Multi-Echo Fast Spin-Echo Pulse Sequence for Accurate R2 Measurement in the Heart and Liver

    PubMed Central

    Kim, Daniel; Jensen, Jens H.; Wu, Ed X.; Sheth, Sujit S.; Brittenham, Gary M.

    2009-01-01

    Measurement of proton transverse relaxation rates (R2) is a generally useful means for quantitative characterization of pathological changes in tissue with a variety of clinical applications. The most widely used R2 measurement method is the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence but its relatively long scan time requires respiratory gating for chest or body MRI, rendering this approach impractical for comprehensive assessment within a clinically acceptable examination time. The purpose of our study was to develop a breath-hold multi-echo fast spin-echo (FSE) sequence for accurate measurement of R2 in the liver and heart. Phantom experiments and studies of subjects in vivo were performed to compare the FSE data with the corresponding even-echo CPMG data. For pooled data, the R2 measurements were strongly correlated (Pearson correlation coefficient = 0.99) and in excellent agreement (mean difference [CPMG-FSE] = 0.10 s−1; 95% limits of agreement were 1.98 and −1.78 s−1) between the two pulse sequences. PMID:19526516

  12. A New Accurate 3D Measurement Tool to Assess the Range of Motion of the Tongue in Oral Cancer Patients: A Standardized Model.

    PubMed

    van Dijk, Simone; van Alphen, Maarten J A; Jacobi, Irene; Smeele, Ludwig E; van der Heijden, Ferdinand; Balm, Alfons J M

    2016-02-01

    In oral cancer treatment, function loss such as speech and swallowing deterioration can be severe, mostly due to reduced lingual mobility. Until now, there is no standardized measurement tool for tongue mobility and pre-operative prediction of function loss is based on expert opinion instead of evidence based insight. The purpose of this study was to assess the reliability of a triple-camera setup for the measurement of tongue range of motion (ROM) in healthy adults and its feasibility in patients with partial glossectomy. A triple-camera setup was used, and 3D coordinates of the tongue in five standardized tongue positions were achieved in 15 healthy volunteers. Maximum distances between the tip of the tongue and the maxillary midline were calculated. Each participant was recorded twice, and each movie was analysed three times by two separate raters. Intrarater, interrater and test-retest reliability were the main outcome measures. Secondly, feasibility of the method was tested in ten patients treated for oral tongue carcinoma. Intrarater, interrater and test-retest reliability all showed high correlation coefficients of >0.9 in both study groups. All healthy subjects showed perfect symmetrical tongue ROM. In patients, significant differences in lateral tongue movements were found, due to restricted tongue mobility after surgery. This triple-camera setup is a reliable measurement tool to assess three-dimensional information of tongue ROM. It constitutes an accurate tool for objective grading of reduced tongue mobility after partial glossectomy.

  13. Polydimethylsiloxane-air partition ratios for semi-volatile organic compounds by GC-based measurement and COSMO-RS estimation: Rapid measurements and accurate modelling.

    PubMed

    Okeme, Joseph O; Parnis, J Mark; Poole, Justen; Diamond, Miriam L; Jantunen, Liisa M

    2016-08-01

    Polydimethylsiloxane (PDMS) shows promise for use as a passive air sampler (PAS) for semi-volatile organic compounds (SVOCs). To use PDMS as a PAS, knowledge of its chemical-specific partitioning behaviour and time to equilibrium is needed. Here we report on the effectiveness of two approaches for estimating the partitioning properties of polydimethylsiloxane (PDMS), values of PDMS-to-air partition ratios or coefficients (KPDMS-Air), and time to equilibrium of a range of SVOCs. Measured values of KPDMS-Air, Exp' at 25 °C obtained using the gas chromatography retention method (GC-RT) were compared with estimates from a poly-parameter free energy relationship (pp-FLER) and a COSMO-RS oligomer-based model. Target SVOCs included novel flame retardants (NFRs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), organophosphate flame retardants (OPFRs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). Significant positive relationships were found between log KPDMS-Air, Exp' and estimates made using the pp-FLER model (log KPDMS-Air, pp-LFER) and the COSMOtherm program (log KPDMS-Air, COSMOtherm). The discrepancy and bias between measured and predicted values were much higher for COSMO-RS than the pp-LFER model, indicating the anticipated better performance of the pp-LFER model than COSMO-RS. Calculations made using measured KPDMS-Air, Exp' values show that a PDMS PAS of 0.1 cm thickness will reach 25% of its equilibrium capacity in ∼1 day for alpha-hexachlorocyclohexane (α-HCH) to ∼ 500 years for tris (4-tert-butylphenyl) phosphate (TTBPP), which brackets the volatility range of all compounds tested. The results presented show the utility of GC-RT method for rapid and precise measurements of KPDMS-Air.

  14. Accurate measurements of Primary Standard Gas Mixtures (PSMs) of CH4 in synthetic and scrubbed real air analyzed by two independent measuring techniques: CRDS and GC-FID

    NASA Astrophysics Data System (ADS)

    Flores, Edgar; Viallon, Joële; Moussay, Philippe; Choteau, Tiphaine; Wielgosz, Robert Ian

    2014-05-01

    In 2013 the BIPM organized the international comparison CCQM-K82 designed to evaluate the level of comparability between National Metrology Institutes (NMI) preparative capabilities for gravimetric methane in air primary reference mixtures in the range (1800-2200) nmol mol-1. This required the development of a measurement facility to compare standards, which was validated prior to the comparison with a suite of ten standards of methane in air prepared gravimetrically by NIST. The mixtures were intentionally prepared in two different air matrices, half in scrubbed real air and half in synthetic, to demonstrate that the use of synthetic air based standards did not introduced any bias for the measurement of atmospheric methane concentrations. The BIPM facility is based on two analytical techniques used under repeatability conditions, namely, cavity ring-down spectroscopy (CRDS) and gas chromatography (GC-FID). GC-FID measurements were performed following a traditional protocol including ratios to a stable control cylinder, giving a typical relative uncertainty of 0.025%. CRDS measurements were performed with the same protocol, but also in a much shorter process that did not use any control cylinder, allowing the reduction of the relative uncertainty to 0.01%. Using the ten standards as references to construct a calibration line, all protocols resulted in a good linearity with very similar residuals. In particular, no effect of the air matrix was observed, as could be especially expected in CRDS due to different pressure broadening parameters, demonstrating the close matching between synthetic and scrubbed real air matrices.

  15. Experimental Methods Using Photogrammetric Techniques for Parachute Canopy Shape Measurements

    NASA Technical Reports Server (NTRS)

    Jones, Thomas W.; Downey, James M.; Lunsford, Charles B.; Desabrais, Kenneth J.; Noetscher, Gregory

    2007-01-01

    NASA Langley Research Center in partnership with the U.S. Army Natick Soldier Center has collaborated on the development of a payload instrumentation package to record the physical parameters observed during parachute air drop tests. The instrumentation package records a variety of parameters including canopy shape, suspension line loads, payload 3-axis acceleration, and payload velocity. This report discusses the instrumentation design and development process, as well as the photogrammetric measurement technique used to provide shape measurements. The scaled model tests were conducted in the NASA Glenn Plum Brook Space Propulsion Facility, OH.

  16. Z/sup 0/ decay modes - experimental measurements

    SciTech Connect

    Dorfan, J.M.

    1984-08-01

    This report summarizes three lectures given at the Theoretical Advanced Study Institute at the University of Michigan at Ann Arbor. The lectures begin with an introduction to storage rings and linear colliders with special reference to the parameters of the SLC and LEP. The rigors of the Z/sup 0/ environment are presented along with the requirements for SLC and LEP detectors. The pedagogy needed for testing the Standard Model is developed, and some experimental tests of the Standard Model are discussed. Tests which involve extensions of the Standard Model (charged Higgs particles, more generations) as well as a few examples of how supersymmetry may show up at the Z/sup 0/ are discussed. 25 references, 34 figures. (WHK)

  17. Experimental Acoustic Velocity Measurements in a Tidally Affected Stream

    USGS Publications Warehouse

    Storm, J.B.; ,

    2002-01-01

    The U.S. Geological Survey (USGS) constructed a continuous steamgaging station on the tidally affected Escatawpa River at Interstate 10 near Orange Grove, Mississippi, in August 2001. The gage collects water quantity parameters of stage and stream velocity, and water quality parameters of water temperature, specific conductance, and salinity. Data are transmitted to the local USGS office via the GOES satellite and are presented on a near real-time web page. Due to tidal effects, the stream has multiple flow regimes which include downstream, bi-directional, and reverse flows. Advances in acoustic technology have made it possible to gage streams of this nature where conventional methods have been unsuccessful. An experimental mount was designed in an attempt to recognize, describe, and quantify these flow regimes by using acoustic Doppler equipment.

  18. Finite element analysis of the effect of electrodes placement on accurate resistivity measurement in a diamond anvil cell with van der Pauw technique

    NASA Astrophysics Data System (ADS)

    Wu, Baojia; Huang, Xiaowei; Han, Yonghao; Gao, Chunxiao; Peng, Gang; Liu, Cailong; Wang, Yue; Cui, Xiaoyan; Zou, Guangtian

    2010-05-01

    The van der Pauw technique is widely used to determine resistivity of materials. In diamond anvil cell the compressed sample will make the contact placement change under high pressure. Using finite element analysis, we study the effect of contact placement error induced by pressure on the resistivity measurement accuracy of van der Pauw method. The results show the contact placement has a significant effect on determination accuracy. This method can provide accurate determination of sample resistivity when the spacing b between the contact center and sample periphery is less than D/9 (sample diameter). And the effect of contact placement error on accuracy rapidly increases as the contact location is closing to the sample center. For the same contact placement, the contact size error has a more obvious effect on the semiconductor sample.

  19. Finite element analysis of the effect of electrodes placement on accurate resistivity measurement in a diamond anvil cell with van der Pauw technique

    SciTech Connect

    Wu Baojia; Huang Xiaowei; Han Yonghao; Gao Chunxiao; Peng Gang; Liu Cailong; Wang Yue; Cui Xiaoyan; Zou Guangtian

    2010-05-15

    The van der Pauw technique is widely used to determine resistivity of materials. In diamond anvil cell the compressed sample will make the contact placement change under high pressure. Using finite element analysis, we study the effect of contact placement error induced by pressure on the resistivity measurement accuracy of van der Pauw method. The results show the contact placement has a significant effect on determination accuracy. This method can provide accurate determination of sample resistivity when the spacing b between the contact center and sample periphery is less than D/9 (sample diameter). And the effect of contact placement error on accuracy rapidly increases as the contact location is closing to the sample center. For the same contact placement, the contact size error has a more obvious effect on the semiconductor sample.

  20. Experimental measurements of unsteady turbulent boundary layers near separation

    NASA Technical Reports Server (NTRS)

    Simpson, R. L.

    1982-01-01

    Investigations conducted to document the behavior of turbulent boundary layers on flat surfaces that separate due to adverse pressure gradients are reported. Laser and hot wire anemometers measured turbulence and flow structure of a steady free stream separating turbulent boundary layer produced on the flow of a wind tunnel section. The effects of sinusoidal and unsteadiness of the free stream velocity on this separating turbulent boundary layer at a reduced frequency were determined. A friction gage and a thermal tuft were developed and used to measure the surface skin friction and the near wall fraction of time the flow moves downstream for several cases. Abstracts are provided of several articles which discuss the effects of the periodic free stream unsteadiness on the structure or separating turbulent boundary layers.

  1. Experimental validation of a high voltage pulse measurement method.

    SciTech Connect

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobates (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensors U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  2. Multicolor laser altimeter for barometric measurements over the ocean - Experimental

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Kalshoven, J. E., Jr.

    1983-01-01

    Measurement theory and results from testing a breadboard multiwavelength (355-, 532- and 1064-nm) laser altimeter over horizontal paths are presented. They show that pressure accuracies of 3 mbar can be achieved when ranging at nadir to cube corner targets when using a 500-psec resolution waveform digitizer and utilizing new calibration techniques. Streak camera-based receivers will be required for the same or higher accuracies when ranging to the ocean surface. System design calculations for aircraft and spaceborne experiments are presented.

  3. Reconstruction of multiple cracks from experimental electrostatic boundary measurements

    NASA Technical Reports Server (NTRS)

    Bryan, Kurt; Liepa, Valdis; Vogelius, Michael

    1993-01-01

    An algorithm for recovering a collection of linear cracks in a homogeneous electrical conductor from boundary measurements of voltages induced by specified current fluxes is described. The technique is a variation of Newton's method and is based on taking weighted averages of the boundary data. An apparatus that was constructed specifically for generating laboratory data on which to test the algorithm is also described. The algorithm is applied to a number of different test cases and the results are discussed.

  4. Experimental evidence of interhemispheric transport from airborne carbon monoxide measurements

    NASA Technical Reports Server (NTRS)

    Newell, R. E.; Gauntner, D. J.

    1979-01-01

    During the period 28-30 October 1977, a Pan American 747-SP aircraft flew around the world with an automated instrument package that included measurements of atmospheric CO made every 4 sec. The flight path extended from San Francisco, over the North Pole to London, south to Capetown, over the South Pole to Auckland, and back to San Francisco. The data collected show large changes with longitude, which are interpreted as direct evidence of interhemispheric mixing. Possible sources for CO are discussed.

  5. S(3) HMBC: Spin-State-Selective HMBC for accurate measurement of homonuclear coupling constants. Application to strychnine yielding thirteen hitherto unreported J(HH).

    PubMed

    Kjaerulff, Louise; Benie, Andrew J; Hoeck, Casper; Gotfredsen, Charlotte H; Sørensen, Ole W

    2016-02-01

    A novel method, Spin-State-Selective (S(3)) HMBC, for accurate measurement of homonuclear coupling constants is introduced. As characteristic for S(3) techniques, S(3) HMBC yields independent subspectra corresponding to particular passive spin states and thus allows determination of coupling constants between detected spins and homonuclear coupling partners along with relative signs. In the presented S(3) HMBC experiment, spin-state selection occurs via large one-bond coupling constants ensuring high editing accuracy and unequivocal sign determination of the homonuclear long-range relative to the associated one-bond coupling constant. The sensitivity of the new experiment is comparable to that of regular edited HMBC and the accuracy of the J/RDC measurement is as usual for E.COSY and S(3)-type experiments independent of the size of the homonuclear coupling constant of interest. The merits of the method are demonstrated by an application to strychnine where thirteen J(HH) coupling constants not previously reported could be measured.

  6. Accurate and absolute diffusion measurements of Rhodamine 6G in low-concentration aqueous solutions by the PGSE-WATERGATE sequence

    SciTech Connect

    Majer, G.; Zick, K.

    2015-04-28

    A pulsed field gradient spin-echo nuclear magnetic resonance (NMR) sequence with solvent suppression (PGSE-WATERGATE) was applied to accurately measure the diffusion coefficients of Rhodamine 6G (Rh6G) in low-concentration aqueous solutions. Three samples with Rh6G concentrations of C{sub Rh6G} = 1, 4.5, and 25 μM were investigated. The precise determination of the diffusion coefficients in this low-concentration range was made possible by using a cryogenically cooled NMR probe and by the effective solvent suppression of the PGSE-WATERGATE sequence. The present results bridge the gap between diffusion data measured by fluorescence correlation spectroscopy in the single molecule limit and diffusivities obtained by pulsed field gradient NMR (PFG-NMR) without solvent suppression at higher concentrations. To further extend the concentration range, the diffusion coefficient of Rh6G was also measured on a sample with C{sub Rh6G} = 410 μM by PFG-NMR. The overall concentration dependence of the Rh6G diffusion at 25 °C is discussed in terms of dimerization of the Rh6G molecules. The concentration-dependent monomer/dimer proportion is deduced from the diffusion data.

  7. Experimentally Measured Radiative Lifetimes and Oscillator Strengths in Neutral Vanadium

    NASA Astrophysics Data System (ADS)

    Holmes, C. E.; Pickering, J. C.; Ruffoni, M. P.; Blackwell-Whitehead, R.; Nilsson, H.; Engström, L.; Hartman, H.; Lundberg, H.; Belmonte, M. T.

    2016-06-01

    We report a new study of the V i atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24,648 cm-1 and 37,518 cm-1 and oscillator strengths for 208 lines between 3040 and 20000 Å from 39 upper energy levels. Thirteen of these oscillator strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and oscillator strengths carried out by Den Hartog et al. and Lawler et al., and thus serves as a means to verify those measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and oscillator strengths. However, we also find evidence that Lawler et al. have systematically underestimated oscillator strengths for lines in the region of 9000 ± 100 Å. We suggest a correction of 0.18 ± 0.03 dex for these values to bring them into agreement with our results and those of Whaling et al. We also report new measurements of hyperfine structure splitting factors for three odd levels of V i lying between 24,700 and 28,400 cm-1.

  8. Experimental measurement of boron isotope fractionation in seawater

    NASA Astrophysics Data System (ADS)

    Klochko, Kateryna; Kaufman, Alan J.; Yao, Wengsheng; Byrne, Robert H.; Tossell, John A.

    2006-08-01

    The boron isotopic composition of marine carbonates is considered to be a tracer of seawater pH. Use of this proxy benefits from an intimate understanding of chemical kinetics and thermodynamic isotope exchange reactions between the two dominant boron-bearing species in seawater: boric acid B(OH) 3 and borate ion B(OH) 4-. However, because of our inability to quantitatively separate these species in solution, the degree of boron isotope exchange has only been known through theoretical estimates. In this study, we present results of a spectrophotometric procedure wherein the boron isotope equilibrium constant ( 11-10KB) is determined empirically from the difference in the dissociation constants of 11B(OH) 3 and 10B(OH) 3 in pure water, 0.6 mol kg - 1 H 2O KCl and artificial seawater. Within experimental uncertainty, our results show no dependence of 11-10KB on temperature, but 11-10KB at 25 °C in pure water was statistically different than results obtained in solutions at high ionic strength. 11-10KB of the seawater ( S = 35, B T = 0.01 mol kg - 1 H 2O) at 25 °C is 1.0272 ± 0.0006. This result is significantly larger than the theoretical value used in numerous paleo-pH studies ( 11-10KB = 1.0194).

  9. Novel experimental design for high pressure-high temperature electrical resistance measurements in a "Paris-Edinburgh" large volume press.

    PubMed

    Matityahu, Shlomi; Emuna, Moran; Yahel, Eyal; Makov, Guy; Greenberg, Yaron

    2015-04-01

    We present a novel experimental design for high sensitivity measurements of the electrical resistance of samples at high pressures (0-6 GPa) and high temperatures (300-1000 K) in a "Paris-Edinburgh" type large volume press. Uniquely, the electrical measurements are carried out directly on a small sample, thus greatly increasing the sensitivity of the measurement. The sensitivity to even minor changes in electrical resistance can be used to clearly identify phase transitions in material samples. Electrical resistance measurements are relatively simple and rapid to execute and the efficacy of the present experimental design is demonstrated by measuring the electrical resistance of Pb, Sn, and Bi across a wide domain of temperature-pressure phase space and employing it to identify the loci of phase transitions. Based on these results, the phase diagrams of these elements are reconstructed to high accuracy and found to be in excellent agreement with previous studies. In particular, by mapping the locations of several well-studied reference points in the phase diagram of Sn and Bi, it is demonstrated that a standard calibration exists for the temperature and pressure, thus eliminating the need for direct or indirect temperature and pressure measurements. The present technique will allow simple and accurate mapping of phase diagrams under extreme conditions and may be of particular importance in advancing studies of liquid state anomalies.

  10. Novel experimental design for high pressure-high temperature electrical resistance measurements in a "Paris-Edinburgh" large volume press

    NASA Astrophysics Data System (ADS)

    Matityahu, Shlomi; Emuna, Moran; Yahel, Eyal; Makov, Guy; Greenberg, Yaron

    2015-04-01

    We present a novel experimental design for high sensitivity measurements of the electrical resistance of samples at high pressures (0-6 GPa) and high temperatures (300-1000 K) in a "Paris-Edinburgh" type large volume press. Uniquely, the electrical measurements are carried out directly on a small sample, thus greatly increasing the sensitivity of the measurement. The sensitivity to even minor changes in electrical resistance can be used to clearly identify phase transitions in material samples. Electrical resistance measurements are relatively simple and rapid to execute and the efficacy of the present experimental design is demonstrated by measuring the electrical resistance of Pb, Sn, and Bi across a wide domain of temperature-pressure phase space and employing it to identify the loci of phase transitions. Based on these results, the phase diagrams of these elements are reconstructed to high accuracy and found to be in excellent agreement with previous studies. In particular, by mapping the locations of several well-studied reference points in the phase diagram of Sn and Bi, it is demonstrated that a standard calibration exists for the temperature and pressure, thus eliminating the need for direct or indirect temperature and pressure measurements. The present technique will allow simple and accurate mapping of phase diagrams under extreme conditions and may be of particular importance in advancing studies of liquid state anomalies.

  11. Experimental measurement of the reflection behavior of contaminant molecules

    NASA Astrophysics Data System (ADS)

    Baba, Susumu; Miyazaki, Eiji; Miura, Yuka; Yamanaka, Riyo; Numata, Osamu; Ishizawa, Junichiro; Kimoto, Yugo; Tamura, Takashi

    2014-09-01

    JAXA is developing a contamination analysis tool "J-SPICE" (Japanese Spacecraft Induced Contamination analysis software). Generally speaking, contamination analysis tools predict based on various input data and mathematical models of contaminant behavior, which means prediction accuracy depends on the validity of mathematical models as well as of input data. We investigated the validity of a diffuse reflection model applied in J-SPICE by comparing the reflection flux of contaminant molecules measured by the ground experiment and the analytical result of the J-SPICE. The result showed that the diffuse reflection model of J-SPICE reasonably explains molecule distribution reflected by a flat surface.